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Sample records for investigate radiation damage

  1. Soft X-Ray Microscopy Radiation Damage On Fixed Cells Investigated With Synchrotron Radiation FTIR Microscopy

    NASA Astrophysics Data System (ADS)

    Gianoncelli, A.; Vaccari, L.; Kourousias, G.; Cassese, D.; Bedolla, D. E.; Kenig, S.; Storici, P.; Lazzarino, M.; Kiskinova, M.

    2015-05-01

    Radiation damage of biological samples remains a limiting factor in high resolution X-ray microscopy (XRM). Several studies have attempted to evaluate the extent and the effects of radiation damage, proposing strategies to minimise or prevent it. The present work aims to assess the impact of soft X-rays on formalin fixed cells on a systematic manner. The novelty of this approach resides on investigating the radiation damage not only with XRM, as often reported in relevant literature on the topic, but by coupling it with two additional independent non-destructive microscopy methods: Atomic Force Microscopy (AFM) and FTIR Microscopy (FTIRM). Human Embryonic Kidney 293 cells were exposed to different radiation doses at 1 keV. In order to reveal possible morphological and biochemical changes, the irradiated cells were systematically analysed with AFM and FTIRM before and after. Results reveal that while cell morphology is not substantially affected, cellular biochemical profile changes significantly and progressively when increasing dose, resulting in a severe breakdown of the covalent bonding network. This information impacts most soft XRM studies on fixed cells and adds an in-depth understanding of the radiation damage for developing better prevention strategies.

  2. Soft X-Ray Microscopy Radiation Damage On Fixed Cells Investigated With Synchrotron Radiation FTIR Microscopy

    PubMed Central

    Gianoncelli, A.; Vaccari, L.; Kourousias, G.; Cassese, D.; Bedolla, D. E.; Kenig, S.; Storici, P.; Lazzarino, M.; Kiskinova, M.

    2015-01-01

    Radiation damage of biological samples remains a limiting factor in high resolution X-ray microscopy (XRM). Several studies have attempted to evaluate the extent and the effects of radiation damage, proposing strategies to minimise or prevent it. The present work aims to assess the impact of soft X-rays on formalin fixed cells on a systematic manner. The novelty of this approach resides on investigating the radiation damage not only with XRM, as often reported in relevant literature on the topic, but by coupling it with two additional independent non-destructive microscopy methods: Atomic Force Microscopy (AFM) and FTIR Microscopy (FTIRM). Human Embryonic Kidney 293 cells were exposed to different radiation doses at 1 keV. In order to reveal possible morphological and biochemical changes, the irradiated cells were systematically analysed with AFM and FTIRM before and after. Results reveal that while cell morphology is not substantially affected, cellular biochemical profile changes significantly and progressively when increasing dose, resulting in a severe breakdown of the covalent bonding network. This information impacts most soft XRM studies on fixed cells and adds an in-depth understanding of the radiation damage for developing better prevention strategies. PMID:25974639

  3. INVESTIGATION OF MICROSCOPIC RADIATION DAMAGE IN WASTE FORMS USING ODNMR AND AEM TECHNIQUES

    EPA Science Inventory

    The proposed project addresses DOE nuclear waste problems that are currently intractable without achieving a fundamental understanding of radiation effects on high level waste (HLW) forms. This project will investigate the microscopic effects of radiation damage in crystalline an...

  4. Atomistic investigation of Cr influence on primary radiation damage in Fe-12 at.% Cr grain boundaries

    NASA Astrophysics Data System (ADS)

    Esfandiarpour, A.; Feghhi, S. A. H.; Arjhangmehr, A.

    2016-08-01

    In this paper, we investigate the influence of Cr on the primary radiation damage in Fe-12 at.% Cr with different atomic grain boundaries (GBs). Four different GB structures, two twists and two symmetric tilt boundaries are selected as the model structures. The primary radiation damage near each GB in α-Fe and Fe-12 at.% Cr is simulated using Molecular Dynamics for 9 keV primary knock-on atoms with velocity vectors perpendicular to the GB plane. In agreement with previous works, the results indicate that the atomic GBs are biased toward interstitials and due to the reduction of ‘in-cascade’ interstitial-vacancy annihilation rates, vacancies accumulate in the bulk grains. The minimum defect production occurs when the overlap between cascade center and GB plane is maximum; in contrast, the number of residual defects in the bulk (vacancies and interstitials) increases when the overlap decreases. Moreover, we find that the presence of Cr hardly affects the number of residual defects in the grain interiors, and causes a Cr-enrichment in the surviving self-interstitial atoms in bulk during relaxation of the primary cascades—also in agreement with previous studies. Further, in order to study the effect of 12 at.% Cr on the energetic and kinetic properties of vacancies near the atomic GBs, we calculate formation energies and diffusion barriers of defects using Molecular Static and climbing-Nudged Elastic Band methods. The results reveal that the vacancies energetically and kinetically tend to form and cluster around the GB plane due to the substantial reduction of their formation energies and migration barriers in layers close to the GB center and are immobile on the simulated time frame (~ps).

  5. Multi-Timescale Investigation of Radiation Damage near TiO2 Rutile Grain Boundaries

    SciTech Connect

    Xian-Ming Bai; Blas P. Uberuaga

    2012-04-01

    Although grain boundaries (GBs) have been experimentally demonstrated to serve as sinks for absorbing radiation induced defects and improving the radiation tolerance of materials, the detailed atomistic interactions between defects and GBs leading to this enhanced tolerance are not well understood. In oxide ceramics the interactions are further complicated as defects can be charged and grain boundaries may exhibit space charge and charge dipole effects. Here, we use two atomistic modeling methods to examine the role of GBs in a model oxide system, rutile TiO2, in modifying defect production during irradiation events. The GB studied is a symmetric tilt GB with a rotation axis of [100] and a rotation angle of 15.25{sup o}. We use molecular dynamics to investigate defect production near the GB at both 300K and 1000 K and find that the damage production is sensitive to the initial distance of the primary knock-on atom (PKA) from the GB. We find three distinct regimes in which GBs have different effects on modifying defect production. Similar to GBs in metals, the GB absorbs more interstitials than vacancies at certain distances while this behavior of biased loading of interstitials diminishes at other distances. Further, we obtain the statistics of both interstitial and vacancy clusters 2 produced in collision cascades in terms of their compositions at two temperatures. We find that perfectly stoichiometric defect clusters (Schottky and anti-Schottky clusters) represent a small fraction of the total defect clusters produced. Moreover, a significant reduction in the number of interstitial clusters at 1000 K compared to 300 K is thought to be a consequence of enhanced migration of interstitials towards the GB. Finally the kinetic properties of certain defect clusters are investigated with temperature accelerated dynamics, without any priori assumptions of migration mechanisms. We find that small interstitial clusters become mobile at high temperatures while small vacancy

  6. Modifying Radiation Damage

    PubMed Central

    Kim, Kwanghee; McBride, William H.

    2011-01-01

    Radiation leaves a fairly characteristic footprint in biological materials, but this is rapidly all but obliterated by the canonical biological responses to the radiation damage. The innate immune recognition systems that sense “danger” through direct radiation damage and through associated collateral damage set in motion a chain of events that, in a tissue compromised by radiation, often unwittingly result in oscillating waves of molecular and cellular responses as tissues attempt to heal. Understanding “nature’s whispers” that inform on these processes will lead to novel forms of intervention targeted more precisely towards modifying them in an appropriate and timely fashion so as to improve the healing process and prevent or mitigate the development of acute and late effects of normal tissue radiation damage, whether it be accidental, as a result of a terrorist incident, or of therapeutic treatment of cancer. Here we attempt to discuss some of the non-free radical scavenging mechanisms that modify radiation responses and comment on where we see them within a conceptual framework of an evolving radiation-induced lesion. PMID:20583981

  7. Theoretical versus Ex Vivo Assessment of Radiation Damage Repair: An Investigation in Normal Breast Tissue.

    PubMed

    Ebert, Martin A; Dhal, Bipina; Prunster, Janelle; McLaren, Sally; Zeps, Nikolajs; House, Michael; Reniers, Brigitte; Verhaegen, Frank; Corica, Tammy; Saunders, Christobel; Joseph, David J

    2016-04-01

    In vivo validation of models of DNA damage repair will enable their use for optimizing clinical radiotherapy. In this study, a theoretical assessment was made of DNA double-strand break (DSB) induction in normal breast tissue after intraoperative radiation therapy (IORT), which is now an accepted form of adjuvant radiotherapy for selected patients with early breast cancer. DSB rates and relative biological effectiveness (RBE) were calculated as a function of dose, radiation quality and dose rate, each varying based on the applicator size used during IORT. The spectra of primary electrons in breast tissue adjacent to each applicator were calculated using measured X-ray spectra and Monte Carlo methods, and were used to inform a Monte Carlo damage simulation code. In the absence of repair, asymptotic RBE values (relative to (60)Co) were approximately 1.5. Beam-quality changes led to only minor variations in RBE among applicators, though differences in dose rate and overall dose delivery time led to larger variations and a rapid decrease in RBE. An experimental assessment of DSB induction was performed ex vivo using pre- and postirradiation tissue samples from patients receiving breast intraoperative radiation therapy. Relative DSB rates were assessed via γ-H2AX immunohistochemistry using proportional staining. Maximum-likelihood parameter estimation yielded a DSB repair halftime of 25.9 min (95% CI, 21.5-30.4 min), although the resulting model was not statistically distinguishable from one where there was no change in DSB yield among patients. Although the model yielded an in vivo repair halftime of the order of previous estimates for in vitro repair halftimes, we cannot conclude that it is valid in this context. This study highlights some of the uncertainties inherent in population analysis of ex vivo samples, and of the quantitative limitations of immunohistochemistry for assessment of DSB repair. PMID:27023258

  8. A computational investigation on radiation damage and activation of structural material for C-ADS

    NASA Astrophysics Data System (ADS)

    Liang, Tairan; Shen, Fei; Yin, Wen; Yu, Quanzhi; Liang, Tianjiao

    2015-11-01

    The C-ADS (China Accelerator-Driven Subcritical System) project, which aims at transmuting high-level radiotoxic waste (HLW) and power generation, is now in the research and development stage. In this paper, a simplified ADS model is set up based on the IAEA Th-ADS benchmark calculation model, then the radiation damage as well as the residual radioactivity of the structural material are estimated using the Monte Carlo simulation method. The peak displacement production rate, gas productions, activity and residual dose rate of the structural components like beam window and outer casing of subcritical reactor core are calculated. The calculation methods and the corresponding results provide the basic reference for making reasonable predictions for the lifetime and maintenance operations of the structural material of C-ADS.

  9. Radiation Damage Workshop

    NASA Technical Reports Server (NTRS)

    Stella, P. M.

    1984-01-01

    The availability of data regarding the radiation behavior of GaAs and silicon solar cells is discussed as well as efforts to provide sufficient information. Other materials are considered too immature for reasonable radiation evaluation. The lack of concern over the possible catastrophic radiation degradation in cascade cells is a potentially serious problem. Lithium counterdoping shows potential for removing damage in irradiated P-type material, although initial efficiencies are not comparable to current state of the art. The possibility of refining the lithium doping method to maintain high initial efficiencies and combining it with radiation tolerant structures such as thin BSF cells or vertical junction cells could provide a substantial improvement in EOL efficiencies. Laser annealing of junctions, either those formed ion implantation or diffusion, may not only improve initial cell performance but might also reduce the radiation degradation rate.

  10. Impurity Radiation From The LHCD Launcher During Operation In JET And Investigation Of Launcher Damage

    SciTech Connect

    Kirov, K.K.; Mailloux, J.

    2005-09-26

    In this study, the most likely causes of the enhanced radiation in front of the LHCD launcher are investigated: fast ions from the warm plasma, fast electrons parasitically accelerated in front of the grill and arcs. Evidence for the presence of each of these mechanisms is discussed. The experimental conditions favouring the appearance of these phenomena and their impact on the launcher have also been highlighted.

  11. Thermal damage in Westerly granite investigated by means of Synchrotron radiation based microtomography

    NASA Astrophysics Data System (ADS)

    Fusseis, F.; Schrank, C. E.; Liu, J.

    2012-04-01

    During heating of rocks, material- and orientation induced differences in the thermal expansivity and elastic behavior cause mismatch and heterogeneous stresses between expanding grains. Given sufficient heating, these thermal-elastic stresses cause inelastic deformation, mostly extensive cracking. A special case of thermally induced deformation in natural rocks is the decrepitation of fluid inclusions. Westerly granite, from Maine (USA) is often used as 'model granite' in rock deformation experiments. A number of these experiments investigate the effects of heating on the granite's bulk properties, in particular its strength, elastic properties, and permeability (e.g., Fredrich & Wong, 1986, Wang et al., 1989, Nasseri et al., 2007). Most thermally induced deformation is ascribed to the formation of grain boundary- and intragranular cracks. The contribution of decrepitating fluid inclusions is rarely considered (Hall & Bodnar, 1989). The relative importance of both deformation processes remains to be quantified. This contribution reports on a heating experiment conducted inside a microtomograph at sector 2-BM at the Advanced Photon Source (USA). We heated an unconfined 1 mm diameter, 8 mm long cylinder of Westerly granite in 15 K intervals from room temperature to 668 K. During heating, we acquired 26 three-dimensional microtomographic datasets documenting the evolution of the sample over the entire temperature span with sub-micron resolution. These data permit the most detailed temperature-resolved documentation of thermal cracking and fluid inclusion decrepitation to date. We examine (a) how absolute temperature affects the mechanisms by which thermal damage is accommodated in Westerly granite; (b) the evolution of geometrical characteristics of thermal damage; and (c) the effects of a retrograde overprint on deformation localisation. Fredrich & Wong (1986), JGR 91/B12, 12743-12764. Hall & Bodnar (1989), Tectonophysics 168, 283-296. Nasseri et al. (2007), Int J

  12. Investigation of microscopic radiation damage in waste forms using ODNMR and AEM techniques. (EMSP Project Final Report)

    SciTech Connect

    Liu, G.; Luo, J.; Beitz, J.; Li, S.; Williams, C.; Zhorin, V.

    2000-04-21

    This project seeks to understand the microscopic effects of radiation damage in nuclear waste forms. The authors' approach to this challenge encompasses studies of ceramics and glasses containing short-lived alpha- and beta-emitting actinides with electron microscopy, laser and X-ray spectroscopic techniques, and computational modeling and simulations. In order to obtain information on long-term radiation effects on waste forms, much of the effort is to investigate {alpha}-decay induced microscopic damage in 18-year old samples of crystalline yttrium and lutetium orthophosphates that initially contained {approximately} 1(wt)% of the alpha-emitting isotope {sup 244}Cm (18.1 y half life). Studies also are conducted on borosilicate glasses that contain {sup 244}Cm, {sup 241}Am, or {sup 249}Bk, respectively. The authors attempt to gain clear insights into the properties of radiation-induced structure defects and the consequences of collective defect-environment interactions, which are critical factors in assessing the long-term performance of high-level nuclear waste forms.

  13. INSTRUMENTS AND METHODS OF INVESTIGATION: Impurity ion implantation into silicon single crystals: efficiency and radiation damage

    NASA Astrophysics Data System (ADS)

    Vavilov, V. S.; Chelyadinskii, Aleksei R.

    1995-03-01

    The ion implantation method is analysed from the point of view of its efficiency as a technique for doping silicon with donor and acceptor impurities, for synthesising silicon-based compounds and for producing gettering layers and optoelectronic structures. The introduction, agglomeration, and annealing of radiation-produced defects in ion-implanted silicon are considered. The role of interstitial defects in radiation-related defect formation is estimated. Mechanisms of athermal migration of silicon atoms in the silicon lattice are analysed.

  14. Spectroscopic properties and radiation damage investigation of a diamond based Schottky diode for ion-beam therapy microdosimetry

    SciTech Connect

    Verona, C.; Marinelli, Marco; Verona-Rinati, G.; Magrin, G.; Solevi, P.; Mayer, R.; Grilj, V.; Jakšić, M.

    2015-11-14

    In this work, a detailed analysis of the properties of a novel microdosimeter based on a synthetic single crystal diamond is reported. Focused ion microbeams were used to investigate the device spectropscopic properties as well as the induced radiation damage effects. A diamond based Schottky diode was fabricated by chemical vapor deposition with a very thin detecting region, about 400 nm thick (approximately 1.4 μm water equivalent thickness), corresponding to the typical size in microdosimetric measurements. A 200 × 200 μm{sup 2} square metallic contact was patterned on the diamond surface by standard photolithography to define the sensitive area. Experimental measurements were carried out at the Ruder Boškovic′ Institute microbeam facility using 4 MeV carbon and 5 MeV silicon ions. Ion beam induced charge maps were employed to characterize the microdosimeter response in terms of its charge collection properties. A stable response with no evidence of polarization or memory effects was observed up to the maximum investigated ion beam flux of about 1.7 × 10{sup 9} ions·cm{sup −2}·s{sup −1}. A homogeneity of the response about 6% was found over the sensitive region with a well-defined confinement of the response within the active area. Tests of the radiation damage effect were performed by selectively irradiating small areas of the device with different ion fluences, up to about 10{sup 12} ions/cm{sup 2}. An exponential decrease of the charge collection efficiency was observed with a characteristic decay constant of about 4.8 MGy and 1 MGy for C and Si ions, respectively. The experimental data were analyzed by means of GEANT4 Monte Carlo simulations. A direct correlation between the diamond damaging effect and the Non Ionizing Energy Loss (NIEL) fraction was found. In particular, an exponential decay of the charge collection efficiency with an exponential decay as a function of NIEL is observed, with a characteristic constant of about

  15. Chemical Protection Against Radiation Damage

    ERIC Educational Resources Information Center

    Campaigne, Ernest

    1969-01-01

    Discusses potential war time and medical uses for chemical compounds giving protection against radiation damage. Describes compounds known to protect, research aimed at discovering such compounds, and problems of toxicity. (EB)

  16. Investigation of microscopic radiation damage in waste forms using ODNMR and AEM techniques. 1997 annual progress report

    SciTech Connect

    Liu, G.

    1997-09-01

    'This project seeks to understand the microscopic effects of radiation damage in nuclear waste forms. The authors approach to this challenge encompasses studies in electron microscopy, laser spectroscopy, and computational modeling and simulation. During this first year of the project, efforts have focused on a-decay induced microscopic damage in crystalline orthophosphates (YPO{sub 4} and LuPO{sub 4}) that contain the short-lived a-emitting isotope {sup 244}Cm (t{sub 1/2} = 18.1 y). The samples that they studied were synthesized in 1980 and the initial {sup 244}Cm concentration was {approximately}1%. Studying these materials is of importance to nuclear waste management because of the opportunity to gain insight into accumulated radiation damage and the influence of aging on such damage. These factors are critical to the long-term performance of actual waste forms [1]. Lanthanide orthophosphates, including LuPO{sub 4} and YPO{sub 4}, have been suggested as waste forms for high level nuclear waste [2] and potential hosts for excess weapons plutonium [3,4]. The work is providing insight into the characteristics of these previously known radiation-resistant materials. They have observed loss of crystallinity (partial amorphization) as a direct consequence of prolonged exposure to intense alpha radiolysis in these materials. More importantly, the observation of microscopic cavities in these aged materials provides evidence of significant chemical decomposition that may be difficult to detect in the earlier stages of radiation damage. The preliminary results show that, in characterizing crystalline compounds as high level nuclear waste forms, chemical decomposition effects may be more important than lattice amorphization which has been the focus of many previous studies. More extensive studies, including in-situ analysis of the dynamics of thermal annealing of self-radiation induced amorphization and cavity formation, will be conducted on these aged {sup 244}Cm

  17. Nuclear Radiation Damages Minds!

    ERIC Educational Resources Information Center

    Blai, Boris, Jr.

    Professors Ernest Sternglass (University of Pittsburgh) and Steven Bell (Berry College) have assembled cogent, conclusive evidence indicating that nuclear radiation is associated with impaired cognition. They suggest that Scholastic Aptitude Scores (SATs), which have declined steadily for 19 years, will begin to rise. Their prediction is based on…

  18. Radiation damage evolution in ceramics

    SciTech Connect

    Devanathan, Ramaswami

    2009-09-15

    A review is presented of recent results on radiation damage production, defect accumulation and dynamic annealing in a number of ceramics, such as silicon carbide, zircon and zirconia. Under energetic particle irradiation, ceramics can undergo amorphization by the accumulation of point defects and defect clusters (silicon carbide) or direct impact amorphization (zircon). Ceramics that resist radiation-induced amorphization have mechanisms to dissipate the primary knock-on atom energy, such as replacement collision sequences that leave the lattice undisturbed and low-energy cation site exchange. The presence of engineered mobile defects, such as structural vacancies in stabilized zirconia, can dynamically anneal radiation damage. Thus, defect engineering is a promising strategy to design radiation tolerance for applications such as nuclear waste disposal.

  19. STS-118 Radiator Impact Damage

    NASA Technical Reports Server (NTRS)

    Lear, Dana M.; Hyde, J.; Christiansen, E.; Herrin, J.; Lyons, F.

    2008-01-01

    During the August 2007 STS-118 mission to the International Space Station, a micro-meteoroid or orbital debris (MMOD) particle impacted and completely penetrated one of shuttle Endeavour s radiator panels and the underlying thermal control system (TCS) blanket, leaving deposits on (but no damage to) the payload bay door. While it is not unusual for shuttle orbiters to be impacted by small MMOD particles, the damage from this impact is larger than any previously seen on the shuttle radiator panels. A close-up photograph of the radiator impact entry hole is shown in Figure 1, and the location of the impact on Endeavour s left-side aft-most radiator panel is shown in Figure 2. The aft radiator panel is 0.5-inches thick and consists of 0.011 inch thick aluminum facesheets on the front and back of an aluminum honeycomb core. The front facesheet is additionally covered by a 0.005 inch thick layer of silver-Teflon thermal tape. The entry hole in the silver-Teflon tape measured 8.1 mm by 6.4 mm (0.32 inches by 0.25 inches). The entry hole in the outer facesheet measured 7.4 mm by 5.3 mm (0.29 inches by 0.21 inches) (0.23 inches). The impactor also perforated an existing 0.012 inch doubler that had been bonded over the facesheet to repair previous impact damage (an example that lightning can strike the same place twice, even for MMOD impact). The peeled-back edge around the entry hole, or lip , is a characteristic of many hypervelocity impacts. High velocity impact with the front facesheet fragmented the impacting particle and caused it to spread out into a debris cloud. The debris cloud caused considerable damage to the internal honeycomb core with 23 honeycomb cells over a region of 28 mm by 26 mm (1.1 inches by 1.0 inches) having either been completely destroyed or partially damaged. Figure 3 is a view of the exit hole in the rear facesheet, and partially shows the extent of the honeycomb core damage and clearly shows the jagged petaled exit hole through the backside

  20. Radiation damage of germanium detectors

    NASA Technical Reports Server (NTRS)

    Pehl, R. H.

    1978-01-01

    Energetic particles can produce interstitial-vacancy pairs in a crystal by knocking the atoms from their normal positions. Detectors are unique among semiconductor devices in depending on very low concentrations of electrically active impurities, and also on efficient transport of holes and electrons over relatively large distances. Because the dense regions of damage produced by energetic particles may result in donors and/or acceptors, and also provide trapping sites for holes and electrons, detectors are very sensitive to radiation damage. In addition to these effects occurring within the detector, radiation may also change the characteristics of the exposed surfaces causing unpredictable effects on the detector leakage current. Radiation-induced surface degradation has rarely, if ever, been observed for germanium detectors. The possibility of minimizing hole trapping in charge collection by the use of a high-purity germanium coaxial detector configured with the p (+) contact on the coaxial periphery is discussed.

  1. Investigation into the role of the cholinergic system in radiation-induced damage in the rat liver and ileum

    PubMed Central

    Özyurt, Hazan; Özden, A. Sevgi; Çevİk, Özge; Özgen, Zerrin; ÇadIrcI, Selin; Elmas, Merve Açıkel; Ercan, Feriha; Şener, Göksel; Gören, M.Z.

    2014-01-01

    It has been previously shown that acetylcholine (ACh) may affect pro-inflammatory and anti-inflammatory cytokines. The role of the cholinergic system in radiation-induced inflammatory responses and tissue damage remains unclear. Therefore, the present study was designed to determine the radio-protective properties of the cholinergic system in the ileum and the liver of rats. Rats were exposed to 8-Gy single-fraction whole-abdominal irradiation and were then decapitated at either 36 h or 10 d post-irradiation. The rats were treated either with intraperitoneal physiological saline (1 ml/kg), physostigmine (80 µg/kg) or atropine (50 μg/kg) twice daily for 36 h or 10 d. Cardiac blood samples and liver and ileal tissues were obtained in which TNF-α, IL-1β and IL-10 levels were assayed using ELISA. In the liver and ileal homogenates, caspase-3 immunoblots were performed and myeloperoxidase (MPO) activity was analyzed. Plasma levels of IL-1β and TNF-α increased significantly following radiation (P < 0.01 and P < 0.001, respectively) as compared with non-irradiated controls, and physostigmine treatment prevented the increase in the pro-inflammatory cytokines (P < 0.01 and P < 0.001, respectively). Plasma IL-10 levels were not found to be significantly changed following radiation, whereas physostigmine augmented IL-10 levels during the late phase (P < 0.01). In the liver and ileum homogenates, IL-1β and TNF-α levels were also elevated following radiation, and this effect was inhibited by physostigmine treatment but not by atropine. Similarly, physostigmine also reversed the changes in MPO activity and in the caspase-3 levels in the liver and ileum. Histological examination revealed related changes. Physostigmine experiments suggested that ACh has a radio-protective effect not involving the muscarinic receptors. PMID:24914105

  2. Damage thresholds for terahertz radiation

    NASA Astrophysics Data System (ADS)

    Dalzell, Danielle R.; McQuade, Jill; Vincelette, Rebecca; Ibey, Bennet; Payne, Jason; Thomas, Robert; Roach, W. P.; Roth, Caleb L.; Wilmink, Gerald J.

    2010-02-01

    Several international organizations establish minimum safety standards to ensure that workers and the general population are protected against adverse health effects associated with electromagnetic radiation. Suitable standards are typically defined using published experimental data. To date, few experimental studies have been conducted at Terahertz (THz) frequencies, and as a result, current THz standards have been defined using extrapolated estimates from neighboring spectral regions. In this study, we used computational modeling and experimental approaches to determine tissue-damage thresholds at THz frequencies. For the computational modeling efforts, we used the Arrhenius damage integral to predict damage-thresholds. We determined thresholds experimentally for both long (minutes) and short (seconds) THz exposures. For the long exposure studies, we used an in-house molecular gas THz laser (υ= 1.89 THz, 189.92 mW/cm2, 10 minutes) and excised porcine skin. For the short exposure studies, we used the Free Electron Laser (FEL) at Jefferson Laboratory (υ= 0.1-1.0 THz, 2.0-14.0 mW/cm2, 2 seconds) and wet chamois cloths. Thresholds were determined using conventional damage score determination and probit analysis techniques, and tissue temperatures were measured using infrared thermographic techniques. We found that the FEL was ideal for tissue damage studies, while our in-house THz source was not suitable to determine tissue damage thresholds. Using experimental data, the tissue damage threshold (ED50) was determined to be 7.16 W/cm2. This value was in well agreement with that predicted using our computational models. We hope that knowledge of tissue-damage thresholds at THz frequencies helps to ensure the safe use of THz radiation.

  3. Differential Processing of Low and High LET Radiation Induced DNA Damage: Investigation of Switch from ATM to ATR Signaling

    NASA Technical Reports Server (NTRS)

    Saha, Janapriya; Wang, Minli; Hada, Megumi; Cucinotta, Francis A.

    2011-01-01

    The members of the phosphatidylinositol kinase-like kinase family of proteins namely ataxia-telangiectasia mutated (ATM) and ATM- and Rad3-related (ATR) are directly responsible for the maintenance of genomic integrity by mounting DDR through signaling and facilitating the recruitment of repair factors at the sites of DNA damage along with coordinating the deployment of cell cycle checkpoints to permit repair by phosphorylating Checkpoint kinase Chk1, Chk2 and p53. High LET radiation from GCR (Galactic Cosmic Rays) consisting mainly of protons and high energy and charged (HZE) particles from SPE (Solar Particle Event) pose a major health risk for astronauts on their space flight missions. The determination of these risks and the design of potential safeguards require sound knowledge of the biological consequences of lesion induction and the capability of the cells to counter them. We here strive to determine the coordination of ATM and ATR kinases at the break sites directly affecting checkpoint signaling and DNA repair and whether differential processing of breaks induced by low and high LET radiation leads to possible augmentation of swap of these damage sensors at the sites of DNA damage. Exposure of cells to IR triggers rapid autophosphorylation of serine-1981 that causes dimer dissociation and initiates monomer formation of ATM. ATM kinase activity depends on the disruption of the dimer, which allows access and phosphorylation of downstream ATM substrates like Chk2. Evidence suggests that ATM is activated by the alterations in higher-order chromatin structure although direct binding of ATM to DSB ends may be a crucial step in its activation. On the other hand, in case of ATR, RPA (replication protein A)-coated ssDNA (single-stranded DNA) generated as a result of stalled DNA replication or during processing of chromosomal lesions is crucial for the localization of ATR to sites of DNA damage in association with ATR-interacting protein (ATRIP). Although the

  4. Undulator Radiation Damage Experience at LCLS

    SciTech Connect

    Nuhn, H. D.; Field, C.; Mao, S.; Levashov, Y.; Santana, M.; Welch, J. N.; Wolf, Z.

    2015-01-06

    The SLAC National Accelerator Laboratory has been running the Linac Coherent Light Source (LCLS), the first x-ray Free Electron Laser since 2009. Undulator magnet damage from radiation, produced by the electron beam traveling through the 133-m long straight vacuum tube, has been and is a concern. A damage measurement experiment has been performed in 2007 in order to obtain dose versus damage calibrations. Radiation reduction and detection devices have been integrated into the LCLS undulator system. The accumulated radiation dose rate was continuously monitored and recorded. In addition, undulator segments have been routinely removed from the beamline to be checked for magnetic (50 ppm, rms) and mechanic (about 0.25 µm, rms) changes. A reduction in strength of the undulator segments is being observed, at a level, which is now clearly above the noise. Recently, potential sources for the observed integrated radiation levels have been investigated. The paper discusses the results of these investigation as well as comparison between observed damage and measured dose accumulations and discusses, briefly, strategies for the new LCLS-II upgrade, which will be operating at more than 300 times larger beam rate.

  5. Correlation between thermoluminescence and radiation damage in bismuth germanate

    SciTech Connect

    Melcher, C.L.

    1985-02-01

    Thermoluminescence properties of bismuth germanate and their relationship to radiation damage characteristics have been investigated. Thermoluminescence and radiation damage in bismuth germanate display several similar properties including similar responses as a function of radiation dose, similar saturation levels, and similar decay times. Also a correlation was found between the thermoluminescence sensitivities and radiation damage sensitivities of four different crystals. The traps responsible for the radiation damage and those which store the thermoluminescence signal appear to be either closely related or actually the same traps. Four trapping centers can be seen in the thermoluminescence glow curves. The depth of the dominant trap is 1.1 eV. 10 references.

  6. Density Functional Theory Models for Radiation Damage

    NASA Astrophysics Data System (ADS)

    Dudarev, S. L.

    2013-07-01

    Density functional theory models developed over the past decade provide unique information about the structure of nanoscale defects produced by irradiation and about the nature of short-range interaction between radiation defects, clustering of defects, and their migration pathways. These ab initio models, involving no experimental input parameters, appear to be as quantitatively accurate and informative as the most advanced experimental techniques developed for the observation of radiation damage phenomena. Density functional theory models have effectively created a new paradigm for the scientific investigation and assessment of radiation damage effects, offering new insight into the origin of temperature- and dose-dependent response of materials to irradiation, a problem of pivotal significance for applications.

  7. Radiation damage in nanostructured metallic films

    NASA Astrophysics Data System (ADS)

    Yu, Kaiyuan

    High energy neutron and charged particle radiation cause microstructural and mechanical degradation in structural metals and alloys, such as phase segregation, void swelling, embrittlement and creep. Radiation induced damages typically limit nuclear materials to a lifetime of about 40 years. Next generation nuclear reactors require materials that can sustain over 60 - 80 years. Therefore it is of great significance to explore new materials with better radiation resistance, to design metals with favorable microstructures and to investigate their response to radiation. The goals of this thesis are to study the radiation responses of several nanostructured metallic thin film systems, including Ag/Ni multilayers, nanotwinned Ag and nanocrystalline Fe. Such systems obtain high volume fraction of boundaries, which are considered sinks to radiation induced defects. From the viewpoint of nanomechanics, it is of interest to investigate the plastic deformation mechanisms of nanostructured films, which typically show strong size dependence. By controlling the feature size (layer thickness, twin spacing and grain size), it is applicable to picture a deformation mechanism map which also provides prerequisite information for subsequent radiation hardening study. And from the viewpoint of radiation effects, it is of interest to explore the fundamentals of radiation response, to examine the microstructural and mechanical variations of irradiated nanometals and to enrich the design database. More importantly, with the assistance of in situ techniques, it is appealing to examine the defect generation, evolution, annihilation, absorption and interaction with internal interfaces (layer interfaces, twin boundaries and grain boundaries). Moreover, well-designed nanostructures can also verify the speculation that radiation induced defect density and hardening show clear size dependence. The focus of this thesis lies in the radiation response of Ag/Ni multilayers and nanotwinned Ag

  8. Protein damage, radiation sensitivity and aging.

    PubMed

    Radman, Miroslav

    2016-08-01

    This paper promotes a concept that protein damage determines radiation resistance and underlies aging and age-related diseases. The first bottleneck in cell recovery from radiation damage is functional (proteome) rather than informational (DNA), since prokaryotic and eukaryotic cell death correlates with incurred protein, but not DNA, damage. Proteome protection against oxidative damage determines survival after ionizing or UV irradiation, since sufficient residual proteome activity is required to turn on the DNA damage response activating DNA repair and protein renewal processes. Extreme radiation and desiccation resistance of rare bacterial and animal species is accounted for by exceptional constitutive proteome protection against oxidative damage. After excessive radiation their well-protected proteome faithfully reconstitutes a transcription-competent genome from hundreds of DNA fragments. The observation that oxidative damage targeted selectively to cellular proteins results in aging-like phenotypes suggests that aging and age-related diseases could be phenotypic consequences of proteome damage patterns progressing with age. PMID:27264559

  9. Investigation of switch from ATM to ATR signaling at the sites of DNA damage induced by low and high LET radiation.

    PubMed

    Saha, Janapriya; Wang, Minli; Cucinotta, Francis A

    2013-12-01

    Upon induction of DNA damage by ionizing radiation (IR), members of the phosphatidylinositol 3-kinase-like kinase family of proteins namely ataxia-telangiectasia mutated (ATM), DNA-PKcs, and ATM- and Rad3-related (ATR) maintain genomic integrity by mounting DNA damage response (DDR). Recent reports suggest that activation of ATM and ATR are oppositely regulated by the length of single stranded overhangs generated during end processing by nucleases at the break sites. These stretches of single stranded overhangs hold the clue for the transition from ATM to ATR signaling at broken DNA ends. We investigated whether differential processing of breaks induced by low and high LET radiation augments the phenomenon of switching from ATM to ATR kinase and hence a concomitant NHEJ to HR transition at the sites of DNA damage. 82-6 human fibroblasts were irradiated with 1 or 2Gy of γ-rays and particle radiation of increasing LET in order to increase the complexity and variability of DNA double strand breaks (DSB) structures. The activation kinetics of ATM and ATR kinases along with their downstream substrates were determined utilizing Western blotting and immunofluorescence techniques. Our data provide evidence of a potential switch from ATM to ATR kinase signaling in cells treated with γ-rays at approximately 2h post irradiation, with induction and completion of resection denoted by Rad51 foci resolution kinetics and observed with a significant decline of phosphorylated ATR kinase 8h after IR. On the other hand, irradiation with high LET 600MeV/u (56)Fe (180keV/μm) and 170MeV/u (28)Si (99keV/μm) particles show a similar Rad51 foci decay kinetics, however, exhibiting prolonged resection, evident by the persistent phosphorylated ATM and ATR kinase until 24h post irradiation. This residual effect, however, was significantly reduced for 250MeV/u (16)O particles of moderate LET (25keV/μm) and absent for γ-rays. Hence, our results support the hypothesis that the transition

  10. Radiation damage effects in zircon

    NASA Astrophysics Data System (ADS)

    Trachenko, Kostya; Dove, Martin; Salje, Ekhard

    2002-03-01

    Zircon, ZrSiO_4, is important for geology and geochronology, and has been proposed as a host material to immobilize highly radioactive materials from dismantled weapons and nuclear waste from power stations [1]. In these applications zircon is exposed to alpha-irradiation. Computer simulations have started to be employed to simulate radiation damage in zircon [2], but the origin and microscopic mechanisms of the most important structural changes in zircon - unit cell expansion and large macroscopic swelling at higher doses, strong shear deformation of the crystalline lattice, and polymerization of SiOn units [3], remain unknown. Here, we perform the molecular dynamics simulation of highly energetic recoils in zircon. Basing on the simulation results, we propose the simple picture of the density change in the damaged region that consists of the depleted and densified matter. We find that the experimentally observed structural changes originate from the interaction of the damaged region with the surrounding crystalline lattice: the shear of the lattice around the damaged region causes shear deformation and expansion of the unit cells. The polymers of connected SiOn polyhedra are most commonly present in the densified shell at the periphery of the damaged region. [1] R C Ewing et al, J. Mater. Res. 10, 243 (1995); W J Weber et al, B E Burakov et al, in Scientific Basis for Nuclear Waste Management XIX, 25-32 and 33-40 (Plenum, New York, 1996); R C Ewing, et al in Crystalline Ceramics: Waste Forms for the Disposal of Weapons Plutonium, NATO Workshop Proceedings 65 (Academic Publishers, Dordrecht, The Netherlands, 1996). [2] B Park et al, Phys. Rev. B, 64, 174108 (1-16) (2001); J P Crocombette and D Ghaleb, J. Nucl. Mater., 295, 167 (2001); K Trachenko et al, J. Appl. Phys., 87, 7702 (2000); K Trachenko et al, J. Phys.: Cond. Matt., 13, 1947 (2001). [3] T Murakami et al, Am. Min., 76, 1510 (1991); H D Holland and D Gottfried, Acta Cryst. 8, 291 (1955).; W J Weber, J. Am

  11. Repair of radiation damage in mammalian cells

    SciTech Connect

    Setlow, R.B.

    1981-01-01

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

  12. Radiation damage of transition metal carbides

    SciTech Connect

    Dixon, G.

    1991-01-01

    In this grant period we have investigated electrical properties of transition metal carbides and radiation-induced defects produced by low-temperature electron irradiation in them. Special attention has been given to the composition VC[sub 0.88] in which the vacancies on the carbon sublattice of this fcc crystal order to produce a V[sub 8]C[sub 7] superlattice. The existence of this superlattice structure was found to make the crystal somewhat resistant to radiation damage at low doses and/or at ambient temperature. At larger doses significant changes in the resistivity are produced. Annealing effects were observed which we believe to be connected with the reconstitution of the superlattice structure.

  13. Radiation damage in barium fluoride detector materials

    SciTech Connect

    Levey, P.W.; Kierstead, J.A.; Woody, C.L.

    1988-01-01

    To develop radiation hard detectors, particularly for high energy physics studies, radiation damage is being studied in BaF/sub 2/, both undoped and doped with La, Ce, Nd, Eu, Gd and Tm. Some dopants reduce radiation damage. In La doped BaF/sub 2/ they reduce the unwanted long lifetime luminescence which interferes with the short-lived fluorescence used to detect particles. Radiation induced coloring is being studied with facilities for making optical measurements before, during and after irradiation with /sup 60/C0 gamma rays. Doses of 10/sup 6/ rad, or less, create only ionization induced charge transfer effects since lattice atom displacement damage is negligible at these doses. All crystals studied exhibit color center formation, between approximately 200 and 800 nm, during irradiation and color center decay after irradiation. Thus only measurements made during irradiation show the total absorption present in a radiation field. Both undoped and La doped BaF/sub 2/ develop damage at minimum detectable levels in the UV---which is important for particle detectors. For particle detector applications these studies must be extended to high dose irradiations with particles energetic enough to cause lattice atom displacement damage. In principle, the reduction in damage provided by dopants could apply to other applications requiring radiation damage resistant materials.

  14. Gamma Radiation Damage in Silicon

    NASA Astrophysics Data System (ADS)

    Chang, Chensen

    A theory for interpreting carrier removal in terms of trap production has been derived from the carrier distribution function, which provides a relationship between the carrier removal rate and trap production rates due to the radiation damage. The carrier removal rate is a function of trap production as well as Fermi level position. Also, the carrier removal rate depends on many parameters, which are the density of states of the valance band as well as the conduction band, density of doping impurities, temperature, location of donor and acceptor energy levels and location of trap energy levels. P-type and n-type silicon Schottky diodes are irradiated by cobalt 60 gamma rays. The experimental results show that the carrier removal rate is dependent on the initial carrier concentration. Carrier concentrations are determined by room temperature C-V measurements while the trap production rates are determined by DLTS from measurements from 50 K to room temperature. A model presented by Williams, et al. for the carrier concentration vs. fluence, has been rederived from simple semiconductor carrier statistical mechanics. This model has then been extended to yield an expression for the initial carrier removal rate which depends on the production rate of each defect trap level in the band gap. We have tested these models thoroughly for the first time by measuring the trap production rates by DLTS, and then, using this information to calculate carrier removal rate and carrier concentration vs. fluence, we have verified that the results of the model can explain these same relationships obtained experimentally by C-V measurements. We believe that this is the first time that DLTS results have been linked directly to such simple and useful measurements as carrier removal rate and carrier concentration vs. fluence in a convincing manner. The success of this procedure also suggests that there are no "hidden" levels or traps which contribute to carrier removal rate but which do not

  15. Investigating α-particle radiation damage in phyllosilicates using synchrotron microfocus-XRD/XAS: implications for geological disposal of nuclear waste

    NASA Astrophysics Data System (ADS)

    Bower, W. R.; Pearce, C. I.; Pimblott, S. M.; Haigh, S. J.; Mosselmans, J. F. W.; Pattrick, R. A. D.

    2014-12-01

    The response of mineral phases to the radiation fields that will be experienced in a geological disposal facility (GDF) for nuclear waste is poorly understood. Phyllosilicates are critical phases in a GDF with bentonite clay as the backfill of choice surrounding high level wastes in the engineered barrier, and clays and micas forming the most important reactive component of potential host rocks. It is essential that we understand changes in mineral properties and behaviour as a result of damage from both α and γ radiation over long timescales. Radiation damage has been demonstrated to affect the physical integrity and oxidation state1 of minerals which will also influence their ability to react with radionuclides. Using the University of Manchester's newly commissioned particle accelerator at the Dalton Cumbrian Facility, UK, model phyllosilicate minerals (e.g. biotite, chlorite) were irradiated with high energy (5MeV) alpha particles at controlled dose rates. This has been compared alongside radiation damage found in naturally formed 'radiohalos' - spherical areas of discolouration in minerals surrounding radioactive inclusions, resulting from alpha particle penetration, providing a natural analogue to study lattice damage under long term bombardment1,2. Both natural and artificially irradiated samples have been analysed using microfocus X-ray absorption spectroscopy and high resolution X-ray diffraction mapping on Beamline I18 at Diamond Light Source; samples were probed for redox changes and long/short range disorder. This was combined with lattice scale imaging of damage using HR-TEM (TitanTM Transmission Electron Microscope). The results show aberrations in lattice parameters as a result of irradiation, with multiple damage-induced 'domains' surrounded by amorphous regions. In the naturally damaged samples, neo-formed phyllosilicate phases are shown to be breakdown products of highly damaged regions. A clear reduction of the Fe(III) component has been

  16. Seismic Radiation from Material Damage During Explosions

    NASA Astrophysics Data System (ADS)

    Rodgers, A. J.; Ben-Zion, Y.

    2010-12-01

    Recent theoretical results on seismic representation from regions undergoing rapid material damage indicate that changes of elastic moduli can produce radiation that may be, in some cases, a significant portion of (or even larger than) the radiation from the standard moment source (Ben-Zion and Ampuero, 2009). The additional radiation is associated with a “damage-related source term” involving the product of the changes in the elasticity tensor and the total elastic strain tensor. The damage source term is non-zero in a certain volume where brittle damage occurs. The generated seismic motion can be computed, as for the classical moment source, by a convolution of the damage density in the affected volume with the spatial derivative of a Green’s functions for an earth model. Here we attempt to provide estimates of the amount and types (isotropic and deviatoric) of the damage related radiation for explosion scenarios. Using both analytic solutions and three-dimensional elastic finite difference calculations, we compute and compare the waves generated by the classical moment and damage related source terms in a full space. We assume a purely isotropic explosion of size corresponding to low-yield nuclear explosions, a granite (hard-rock) whole-space, and that the damage occurs instantaneously. Using a simple iterative approach, we adjust the strain ɛij where it exceeds the yield strength of the rock ɛij_c and reduce the local elastic moduli in proportion to the difference (ɛij - ɛij_c). The calculated adjustments to the strain and reduction of elastic moduli are used to estimate the additional moment contribution due to excess strain (ɛij - ɛij_c) and the associated damage source term in the yielding region. Finally, the seismic radiation from the brittle damage process is computed and compared to the radiation generated by the moment of the explosion source and the additional inelastic relaxation in the yielding region.

  17. DNA Damage Signals and Space Radiation Risk

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2011-01-01

    Space radiation is comprised of high-energy and charge (HZE) nuclei and protons. The initial DNA damage from HZE nuclei is qualitatively different from X-rays or gamma rays due to the clustering of damage sites which increases their complexity. Clustering of DNA damage occurs on several scales. First there is clustering of single strand breaks (SSB), double strand breaks (DSB), and base damage within a few to several hundred base pairs (bp). A second form of damage clustering occurs on the scale of a few kbp where several DSB?s may be induced by single HZE nuclei. These forms of damage clusters do not occur at low to moderate doses of X-rays or gamma rays thus presenting new challenges to DNA repair systems. We review current knowledge of differences that occur in DNA repair pathways for different types of radiation and possible relationships to mutations, chromosomal aberrations and cancer risks.

  18. Investigation of Combined Action of Food Supplement's and Ionizing Radiation on the Cytogenetic Damage Induction and Ehrlich Ascite Carcinoma Growth on Mice in Vivo

    NASA Astrophysics Data System (ADS)

    Sorokina, Svetlana; Zaichkina, Svetlana; Dyukina, Alsu; Rozanova, Olga; Balakin, Vladimir; Peleshko, Vladimir; Romanchenko, Sergey; Smirnova, Helena; Aptikaeva, Gella; Shemyakov, Alexander

    In recent ten years one of the major problems of modern radiobiology is the study of radiation protective mechanisms with the help of different substances as well as activation of internal resources of the organism. Internal resources mean such phenomena as hormesis and adaptive response which represent cell or body reaction on low doses of inducing factors and predetermine their further high dose effect resistance. At present special interest is attracted by studies of biological effects of low-dose-rate high-LET radiation because of searching for new types of radiation for more effective cancer therapy and searching for new methods of radiation protection. Since natural biologically active substances have low toxicity and are capable of affecting physiological processes taking place in human’s organism and increasing organism’s natural defense system, the interest to protective means of vegetal origin and search of special food supplements intensifies every year. The purpose of this study is to investigate the combined influence of food supplement, low dose rate high-LET radiation simulating high-altitude flight conditions and X-ray radiations on radiosensitivity, induction of radiation adaptive response (RAR) and growth of Ehrlich ascite carcinoma as well. Experiments were performed with males of SHK mice at the age of two months. The animals were being irradiated with low-dose-rate high-LET radiation with the dose of 11,6 cGy (0,5 cGy/day) behind the concrete shield of the 70 GeV protons accelerator (Protvino). The X-ray irradiation was carried out on the RTH device with a voltage of 200 kV (1 Gy/min; Pushchino). The diet composition included products containing big amount of biologically active substances, such as: soybeam meat, buckwheat, lettuce leaves and drug of cod-liver oil. Four groups of mice were fed with selected products mentioned above during the whole irradiation period of 22 days. The control groups received the same food without irradiation

  19. Enhanced annealing of GaAs solar cell radiation damage

    NASA Technical Reports Server (NTRS)

    Loo, R.; Knechtli, R. C.; Kamath, G. S.

    1981-01-01

    Solar cells are degraded by radiation damage in space. Investigations have been conducted concerning possibilities for annealing this radiation damage in GaAs solar cells, taking into account the conditions favoring such annealing. It has been found that continuous annealing as well as the combination of injection annealing with thermal annealing can lead to recovery from radiation damage under particularly favorable conditions in GaAs solar cells. The damage caused by both electrons and protons in GaAs solar cells can be substantially reduced by annealing at temperatures as low as 150 C, under appropriate conditions. This possibility makes the GaAs solar cells especially attractive for long space missions, or for missions in severe radiation environments. Attention is given to results concerning periodic thermal annealing, continuous annealing, and injection annealing combined with thermal annealing.

  20. Influence of Detector Radiation Damage on CR Mammography Quality Control.

    PubMed

    Moriwaki, Atsumi; Ishii, Mie; Terazono, Shiho; Arao, Keiko; Ishii, Rie; Sanada, Taizo; Yoshida, Akira

    2016-05-01

    Recently, radiation damage to the detector apparatus employed in computed radiography (CR) mammography has become problematic. The CR system and the imaging plate (IP) applied to quality control (QC) program were also used in clinical mammography in our hospital, and the IP to which radiation damage has occurred was used for approximately 5 years (approximately 13,000 exposures). We considered using previously acquired QC image data, which is stored in a server, to investigate the influence of radiation damage to an IP. The mammography unit employed in this study was a phase contrast mammography (PCM) Mermaid (KONICA MINOLTA) system. The QC image was made newly, and it was output in the film, and thereafter the optical density of the step-phantom image was measured. An input (digital value)-output (optical density) conversion curve was plotted using the obtained data. The digital values were then converted to optical density values using a reference optical density vs. digital value curve. When a high radiation dose was applied directly, radiation damage occurred at a position on the IP where no object was present. Daily QC for mammography is conducted using an American College of Radiology (ACR) accreditation phantom and acrylic disc, and an environmental background density measurement is performed as one of the management indexes. In this study, the radiation damage sustained by the acrylic disc was shown to differ from that of the background. Thus, it was revealed that QC results are influenced by radiation damage. PMID:27211088

  1. The expected radiation damage of CSNS target

    NASA Astrophysics Data System (ADS)

    Yin, W.; Yu, Q. Z.; Lu, Y. L.; Wang, S. L.; Tong, J. F.; Liang, T. J.

    2012-12-01

    The radiation damage to the tungsten target and its SS316 vessel for Chinese Spallation Neutron Source (CSNS) has been estimated with a Monte-Carlo simulation code MCNPX2.5.0. We compare the effects on the radiation damage due to two different proton beam profiles: a uniform distribution and a Gaussian distribution. We also discuss the dependence of the radiation damage estimation on different physics models. The results show the peak displacement productions in vessel and the fourth target plate are 2.5 and 5.5 dpa/y, respectively, under a Gaussian proton beam. The peak helium productions in the vessel and the fourth target are 305 and 353 appm/y, respectively, under the same proton beam. Based on these results and the allowable dpa values we have estimated the lifetime of the tungsten target and its vessel.

  2. Nanofoams Response to Radiation Damage

    SciTech Connect

    Fu, Engang; Serrano De Caro, Magdalena; Wang, Yongqiang; Nastasi, Michael; Zepeda-Ruiz, Luis; Bringa, Eduardo M.; Baldwin, Jon K.; Caro, Jose A.

    2012-07-30

    Conclusions of this presentation are: (1) np-Au foams were successfully synthesized by de-alloying process; (2) np-Au foams remain porous structure after Ne ion irradiation to 1 dpa; (3) SFTs were observed in irradiated np-Au foams with highest and intermediate flux, while no SFTs were observed with lowest flux; (4) SFTs were observed in irradiated np-Au foams at RT, whereas no SFTs were observed at LNT irradiation; (5) The diffusivity of vacancies in Au at RT is high enough so that the vacancies have enough time to agglomerate and thus collapse. As a result, SFTs were formed; (6) The high flux created much more damage/time, vacancies don't have enough time to diffuse or recombine. As a result, SFTs were formed.

  3. Radiation damage in MINP cells

    NASA Astrophysics Data System (ADS)

    Minahan, J. A.; Green, M. J.

    Experiments have been carried out to examine the effects of exposure to various fluence levels of 1 MeV electrons on 0.2 ohm-cm MINP silicon solar cell characteristics. Fluence levels ranged from 10 to the 14th e/sq cm to 3 x 10 to the 15th e/sq cm. Minority carrier diffusion lengths, Lbase, were derived from short circuit current calculations that included corrections for surface shadowing, reflection and emitter contribution to the short circuit current. From Lbase and fluences, a damage coefficient for diffusion length was calculated (1.4 x 10 to the -9th/electron) and compared with results obtained for other cell designs and base resistivities.

  4. Probing Radiation Damage at the Molecular Level

    NASA Astrophysics Data System (ADS)

    Mason, N. J.; Smialek, M. A.; Moore, S. A.; Folkard, M.; Hoffmann, S. V.

    2006-12-01

    Radiation damage of DNA and other cellular components has traditionally been attributed to ionisation via direct impact of high-energy quanta or by complex radical chemistry. However recent research has shown that strand breaks in DNA may be initiated by secondary electrons and is strongly dependent upon the target DNA base identity. Such research provides the fascinating perspective that it is possible that radiation damage may be described and understood at an individual molecular level introducing new possibilites for therapy and perhaps providing an insight into the origins of life.

  5. Radiation damage effects in polarized deuterated ammonia

    SciTech Connect

    P.M. McKee

    2003-07-01

    Solid polarized targets utilizing deuterated ammonia, {sup 15}ND{sub 3}, offer an attractive combination of high polarization, high dilution factor and high resistance to polarization losses from radiation damage. Jefferson Laboratory Experiment E93-026 used {sup 15}ND{sub 3} as a target material in a five-month form factor measurement, allowing a detailed study of it's performance. The dependence of the deuteron polarization on received dose by the ammonia and the effectiveness of annealing the material to recover performance lost to radiation damage will be discussed.

  6. Elastic softening of zircon by radiation damage

    SciTech Connect

    Salje, Ekhard K. H.

    2006-09-25

    The bulk modulus and the shear modulus of zircon soften by ca. 50% when zircon is amorphized by radiation damage. A theoretical description of the experimental findings is presented which shows that the elastic response on a zircon ceramics with radiation damage follows Hashin-Shtrikman [J. Mech. Phys. Solids 11, 127 (1963)] behavior with very narrow bounds. The elastic response depends, in good approximation, on the square of the volume fraction f{sub a} of the amorphized regions. In a slightly coarser approximation one finds an almost linear interpolation of the bulk and the shear modulus between those of the crystalline state and those of the fully amorphous state.

  7. Radiation damage to nucleoprotein complexes in macromolecular crystallography

    PubMed Central

    Bury, Charles; Garman, Elspeth F.; Ginn, Helen Mary; Ravelli, Raimond B. G.; Carmichael, Ian; Kneale, Geoff; McGeehan, John E.

    2015-01-01

    Significant progress has been made in macromolecular crystallography over recent years in both the understanding and mitigation of X-ray induced radiation damage when collecting diffraction data from crystalline proteins. In contrast, despite the large field that is productively engaged in the study of radiation chemistry of nucleic acids, particularly of DNA, there are currently very few X-ray crystallographic studies on radiation damage mechanisms in nucleic acids. Quantitative comparison of damage to protein and DNA crystals separately is challenging, but many of the issues are circumvented by studying pre-formed biological nucleoprotein complexes where direct comparison of each component can be made under the same controlled conditions. Here a model protein–DNA complex C.Esp1396I is employed to investigate specific damage mechanisms for protein and DNA in a biologically relevant complex over a large dose range (2.07–44.63 MGy). In order to allow a quantitative analysis of radiation damage sites from a complex series of macromolecular diffraction data, a computational method has been developed that is generally applicable to the field. Typical specific damage was observed for both the protein on particular amino acids and for the DNA on, for example, the cleavage of base-sugar N1—C and sugar-phosphate C—O bonds. Strikingly the DNA component was determined to be far more resistant to specific damage than the protein for the investigated dose range. At low doses the protein was observed to be susceptible to radiation damage while the DNA was far more resistant, damage only being observed at significantly higher doses. PMID:25723923

  8. Probing Radiation Damage in Plutonium Alloys with Multiple Measurement Techniques

    SciTech Connect

    McCall, S K; Fluss, M J; Chung, B W

    2010-04-21

    A material subjected to radiation damage will usually experience changes in its physical properties. Measuring these changes in the physical properties provides a basis to study radiation damage in a material which is important for a variety of real world applications from reactor materials to semiconducting devices. When investigating radiation damage, the relative sensitivity of any given property can vary considerably based on the concentration and type of damage present as well as external parameters such as the temperature and starting material composition. By measuring multiple physical properties, these differing sensitivities can be leveraged to provide greater insight into the different aspects of radiation damage accumulation, thereby providing a broader understanding of the mechanisms involved. In this report, self-damage from {alpha}-particle decay in Pu is investigated by measuring two different properties: magnetic susceptibility and resistivity. The results suggest that while the first annealing stage obeys second order chemical kinetics, the primary mechanism is not the recombination of vacancy-interstitial close pairs.

  9. The Status of Radiation Damage Experiments

    SciTech Connect

    Strachan, Denis M.; Scheele, Randall D.; Icenhower, Jonathan P.; Kozelisky, Anne E.; Sell, Richard L.; Legore, Virginia L.; Schaef, Herbert T.; O'Hara, Matthew J.; Brown, Christopher F.; Buchmiller, William C.

    2001-11-20

    Experiments have been on-going for about two years to determine the effects that radiation damage have on the physical and chemical properties of candidate titanate ceramics for the immobilization of plutonium. We summarize the results of these experiments in this document.

  10. Acoustic emission sensor radiation damage threshold experiment

    SciTech Connect

    Beeson, K.M.; Pepper, C.E.

    1994-09-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ``false negative or false positive`` indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments.

  11. Gallium arsenide solar cell radiation damage study

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Herbert, G. A.; Kinnison, J. D.; Meulenberg, A.

    1989-01-01

    A thorough analysis has been made of electron- and proton- damaged GaAs solar cells suitable for use in space. It is found that, although some electrical parametric data and spectral response data are quite similar, the type of damage due to the two types of radiation is different. An I-V analysis model shows that electrons damage the bulk of the cell and its currents relatively more, while protons damage the junction of the cell and its voltages more. It is suggested that multiple defects due to protons in a strong field region such as a p/n junction cause the greater degradation in cell voltage, whereas the individual point defects in the quasi-neutral minority-carrier-diffusion regions due to electrons cause the greater degradation in cell current and spectral response.

  12. Investigating chromosome damage and gammaH2AX response in human lymphocytes and lymphocyte subsets as potential biomarkers of radiation sensitivity

    NASA Astrophysics Data System (ADS)

    Beaton, Lindsay A.

    This thesis examines in vitro irradiated blood samples from prostate cancer patients exhibiting late normal tissue damage after receiving radiotherapy, for lymphocyte response. Chromosomal aberrations, translocations and proliferation rate are measured, as well as gammaH2AX response in lymphocytes and lymphocyte subsets. The goal of this thesis is to determine whether the lymphocyte response to in vitro radiation could be used as a marker for radiosensitivity. Patients were selected from a randomized clinical trial evaluating the optimal timing of Dose Escalated Radiation and short course Androgen Deprivation Therapy. Of 438 patients, 3% developed Grade 3 late radiation proctitis and were considered to be radiosensitive. Blood was drawn from 10 of these patients along with 20 matched samples from patients with grade 0 proctitis. The samples were irradiated and were analyzed for dicentric chromosomes, excess fragments and proliferation rates (at 6 Gy), translocations, stable and unstable damage (at 4 Gy), and dose response (up to 10 Gy), along with time response after 2 Gy (0 -- 24 h). Chromosome aberrations, excess fragments per cell, translocations per cell and proliferation rates were analyzed by brightfield and fluorescent microscopy, while the gammaH2AX response in lymphocytes and lymphocyte subsets was analyzed by flow cytometry. Both groups were statistically similar for all endpoints at 0 Gy. At 6 Gy, there were statistically significant differences between the radiosensitive and control cohorts for three endpoints; the mean number of dicentric chromosomes per cell, the mean number of excess fragments per cell and the proportion of cells in second metaphase. At 4 Gy, there were statistically significant differences between the two cohorts for three endpoints; the mean number of translocations per cell, the mean number of dicentric chromosomes per cell and the mean number of deletions per cell. There were no significant differences between the gammaH2AX

  13. Nonuniform radiation damage in permanent magnet quadrupoles

    SciTech Connect

    Danly, C. R.; Merrill, F. E.; Barlow, D.; Mariam, F. G.

    2014-08-15

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL’s pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components.

  14. Nonuniform radiation damage in permanent magnet quadrupoles.

    PubMed

    Danly, C R; Merrill, F E; Barlow, D; Mariam, F G

    2014-08-01

    We present data that indicate nonuniform magnetization loss due to radiation damage in neodymium-iron-boron Halbach-style permanent magnet quadrupoles. The proton radiography (pRad) facility at Los Alamos uses permanent-magnet quadrupoles for magnifying lenses, and a system recently commissioned at GSI-Darmsdadt uses permanent magnets for its primary lenses. Large fluences of spallation neutrons can be produced in close proximity to these magnets when the proton beam is, intentionally or unintentionally, directed into the tungsten beam collimators; imaging experiments at LANL's pRad have shown image degradation with these magnetic lenses at proton beam doses lower than those expected to cause damage through radiation-induced reduction of the quadrupole strength alone. We have observed preferential degradation in portions of the permanent magnet quadrupole where the field intensity is highest, resulting in increased high-order multipole components. PMID:25173260

  15. Radiation damage in Luna 20 soil.

    NASA Technical Reports Server (NTRS)

    Phakey, P. P.; Price, P. B.

    1973-01-01

    As an extension of previous studies of radiation damage produced by heavy solar flare ions in lunar soils, high-voltage electron microscopy and electron diffraction procedures were used to rank a Luna 20 sample among the other soils returned by Soviet and American lunar missions. Micron-sized soil grains from the Luna 20 mission are the most lightly irradiated, in contrast to micron-sized grains from Luna 16 soil, which are the most heavily irradiated.

  16. Radiation damage effects on solid state detectors

    NASA Technical Reports Server (NTRS)

    Trainor, J. H.

    1972-01-01

    Totally depleted silicon diodes are discussed which are used as nuclear particle detectors in investigations of galactic and solar cosmic radiation and trapped radiation. A study of radiation and chemical effects on the diodes was conducted. Work on electron and proton irradiation of surface barrier detectors with thicknesses up to 1 mm was completed, and work on lithium-drifted silicon devices with thicknesses of several millimeters was begun.

  17. RNA protects a nucleoprotein complex against radiation damage.

    PubMed

    Bury, Charles S; McGeehan, John E; Antson, Alfred A; Carmichael, Ian; Gerstel, Markus; Shevtsov, Mikhail B; Garman, Elspeth F

    2016-05-01

    Radiation damage during macromolecular X-ray crystallographic data collection is still the main impediment for many macromolecular structure determinations. Even when an eventual model results from the crystallographic pipeline, the manifestations of radiation-induced structural and conformation changes, the so-called specific damage, within crystalline macromolecules can lead to false interpretations of biological mechanisms. Although this has been well characterized within protein crystals, far less is known about specific damage effects within the larger class of nucleoprotein complexes. Here, a methodology has been developed whereby per-atom density changes could be quantified with increasing dose over a wide (1.3-25.0 MGy) range and at higher resolution (1.98 Å) than the previous systematic specific damage study on a protein-DNA complex. Specific damage manifestations were determined within the large trp RNA-binding attenuation protein (TRAP) bound to a single-stranded RNA that forms a belt around the protein. Over a large dose range, the RNA was found to be far less susceptible to radiation-induced chemical changes than the protein. The availability of two TRAP molecules in the asymmetric unit, of which only one contained bound RNA, allowed a controlled investigation into the exact role of RNA binding in protein specific damage susceptibility. The 11-fold symmetry within each TRAP ring permitted statistically significant analysis of the Glu and Asp damage patterns, with RNA binding unexpectedly being observed to protect these otherwise highly sensitive residues within the 11 RNA-binding pockets distributed around the outside of the protein molecule. Additionally, the method enabled a quantification of the reduction in radiation-induced Lys and Phe disordering upon RNA binding directly from the electron density. PMID:27139628

  18. RNA protects a nucleoprotein complex against radiation damage

    PubMed Central

    Bury, Charles S.; McGeehan, John E.; Antson, Alfred A.; Carmichael, Ian; Gerstel, Markus; Shevtsov, Mikhail B.; Garman, Elspeth F.

    2016-01-01

    Radiation damage during macromolecular X-ray crystallographic data collection is still the main impediment for many macromolecular structure determinations. Even when an eventual model results from the crystallographic pipeline, the manifestations of radiation-induced structural and conformation changes, the so-called specific damage, within crystalline macromolecules can lead to false interpretations of biological mechanisms. Although this has been well characterized within protein crystals, far less is known about specific damage effects within the larger class of nucleoprotein complexes. Here, a methodology has been developed whereby per-atom density changes could be quantified with increasing dose over a wide (1.3–25.0 MGy) range and at higher resolution (1.98 Å) than the previous systematic specific damage study on a protein–DNA complex. Specific damage manifestations were determined within the large trp RNA-binding attenuation protein (TRAP) bound to a single-stranded RNA that forms a belt around the protein. Over a large dose range, the RNA was found to be far less susceptible to radiation-induced chemical changes than the protein. The availability of two TRAP molecules in the asymmetric unit, of which only one contained bound RNA, allowed a controlled investigation into the exact role of RNA binding in protein specific damage susceptibility. The 11-fold symmetry within each TRAP ring permitted statistically significant analysis of the Glu and Asp damage patterns, with RNA binding unexpectedly being observed to protect these otherwise highly sensitive residues within the 11 RNA-binding pockets distributed around the outside of the protein molecule. Additionally, the method enabled a quantification of the reduction in radiation-induced Lys and Phe disordering upon RNA binding directly from the electron density. PMID:27139628

  19. Radiation damage calculations for the LANSCE degrader

    SciTech Connect

    Ferguson, P.D.; Sommer, W.F.; Dudziak, D.J.; Wechsler, M.S.; Barnett, M.H.; Corzine, R.K.

    1998-09-01

    The A-6 water degrader at the Los Alamos Neutron Science Center (LANSCE) linear proton accelerator has an outer shell of Inconel 718. The degrader was irradiated by 800-MeV protons during 1988--1993 to an exposure of 5.3 ampere-hours (A h). As described in Ref. 1, material from the Inconel is currently being cut into specimens for microhardness, three-point bending, ball punch, microscopy, and corrosion tests. This paper is devoted to calculations of radiation damage, particularly displacement and He production, sustained by the degrader Inconel.

  20. Radiation damage in cubic-stabilized zirconia

    SciTech Connect

    Costantini, Jean-Marc; Beuneu, Francois; Weber, William J

    2013-01-01

    Cubic yttria-stabilized zirconia (YSZ) can be used for nuclear applications as an inert matrix for actinide immobilization or transmutation. Indeed, the large amount of native oxygen vacancies leads to a high radiation tolerance of this material owing to defect recombination occurring in the atomic displacements cascades induced by fast neutron irradiation or ion implantations, as showed by Molecular dynamics (MD) simulations. Amorphization cannot be obtained in YSZ either by nuclear-collision or electronic-excitation damage, just like in urania. A kind of polygonization structure with slightly disoriented crystalline domains is obtained in both cases. In the first steps of damage, specific isolated point defects (like F+-type color centers) and point-defect clusters are produced by nuclear collisions with charged particles or neutrons. Further increase of damage leads to dislocation-loop formation, then to collapse of the dislocation network into a polygonization structure. For swift heavy ion irradiations, a similar polygonization structure is obtained above a threshold stopping power value of about 20-30 keV nm-1.

  1. Radiation damage in zircon and monazite

    SciTech Connect

    Meldrum, A.; Boatner, L.A.; Weber, W.J.; Ewing, R.C.

    1998-07-01

    Monazite and zircon respond differently to ion irradiation and to thermal and irradiation-enhanced annealing. The damage process (i.e., elastic interactions leading to amorphization) in radioactive minerals (metamictization) is basically the same as for the ion-beam-irradiated samples with the exception of the dose rate which is much lower in the case of natural samples. The crystalline-to-metamict transition in natural samples with different degrees of damage, from almost fully crystalline to completely metamict, is compared to the sequence of microstructures observed for ion-beam-irradiated monazite and zircon. The damage accumulation process, representing the competing effects of radiation-induced structural disorder and subsequent annealing mechanisms (irradiation-enhanced and thermal) occurs at much higher temperatures for zircon than for monazite. The amorphization dose, expressed as displacements per atom, is considerably higher in the natural samples, and the atomic-scale process leading to metamictization appears to develop differently. Ion-beam-induced amorphization data were used to calculate the {alpha}-decay-event dose required for amorphization in terms of a critical radionuclide concentration, i.e., the concentration above which a sample of a given age will become metamict at a specific temperature. This equation was applied to estimate the reliability of U-Pb ages, to provide a qualitative estimate of the thermal history of high-U natural zircons, and to predict whether actinide-bearing zircon or monazite nuclear waste forms will become amorphous (metamict) over long timescales.

  2. Radiation damage in charge-coupled devices.

    PubMed

    Bassler, Niels

    2010-08-01

    Due to their high sensitivity and signal-to-noise ratio, charge-coupled devices (CCDs) have been the preferred optical photon detectors of astronomers for several decades. CCDs are flown in space as the main detection instrument on several well-known missions, such as the Hubble Space Telescope, XMM-Newton or the Cassini Probe. Also, CCDs are frequently used in satellite star trackers which provide attitude information to the satellite orientation system. However, one major drawback is their extreme vulnerability to radiation, which is readily abundant in space. Here, we shall give a brief overview of the radiation effects on CCDs, and mention ways how to mitigate the effects in other ways than merely increase shielding, such as cooling and annealing. As an example, we have investigated the radiation hardness of a particular CCD, the so-called CCD47-20 from Marconi Applied Technologies (now E2V), by exposing it to radiation fields representing the radiation environment found in a highly elliptic orbit crossing the Van-Allen radiation belts. Two engineering-grade CCDs were irradiated with proton beams and photons, and effects of increased bulk dark current, surface dark current and inversion threshold voltage shifts were observed and are quantified. PMID:20238121

  3. Radiation Damage In Reactor Cavity Concrete

    SciTech Connect

    Field, Kevin G; Le Pape, Yann; Naus, Dan J; Remec, Igor; Busby, Jeremy T; Rosseel, Thomas M; Wall, Dr. James Joseph

    2015-01-01

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis (EMDA), jointly performed by the Department of Energy, the Nuclear Regulatory Commission and Industry, identified the urgent need to develop a consistent knowledge base on irradiation effects in concrete. Much of the historical mechanical performance data of irradiated concrete does not accurately reflect typical radiation conditions in NPPs or conditions out to 60 or 80 years of radiation exposure. To address these potential gaps in the knowledge base, The Electric Power Research Institute and Oak Ridge National Laboratory are working to disposition radiation damage as a degradation mechanism. This paper outlines the research program within this pathway including: (i) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), (ii) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, (iii) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, (iv) evaluating opportunities to harvest and test irradiated concrete from international NPPs, (v) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, (vi) furthering the understanding of the effects of radiation on concrete (see companion paper) and (vii) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge.

  4. Synergistic damage by UVA radiation and pollutants.

    PubMed

    Burke, K E; Wei, H

    2009-01-01

    Not only is skin cancer by far the most common human cancer but also the incidence of skin cancer has been increasing at an alarming rate in recent decades. Fortunately, most people now realize that sun exposure causes unattractive photoaging and skin cancer, so they do apply sunscreens conscientiously. However, until recently, most sunscreens did not adequately protect against ultraviolet A (UVA) radiation. Although UVA is indeed less erythrogenic and less carcinogenic than UVB, UVA directly causes photoaging and enhances UVB-induced skin cancer. Furthermore, recent research demonstrates that UVA combined with environmental pollutants (including cigarette smoke) significantly increases the risk of skin cancer. Similarly, previous research demonstrated another synergy between environmental pollutants and UV: When ozone exposure precedes UV exposure, there is enhancement of UV-induced depletion of protective vitamin E from the skin's stratum corneum. This article reviews experimental evidence that environmental pollutants (such as benzo[a]pyrene (BaP), a commonly used index of environmental pollution) are photosensitizers that generate reactive oxygen species (ROS) when exposed to UVA radiation. This in turn causes oxidative and genetic damage, leading to unattractive photodamage and carcinogenesis. PMID:19651790

  5. Synergistic Effect of Triple Ion Beams on Radiation Damage in CLAM Steel

    NASA Astrophysics Data System (ADS)

    Yuan, Da-Qing; Zheng, Yong-Nan; Zuo, Yi; Fan, Ping; Zhou, Dong-Mei; Zhang, Qiao-Li; Ma, Xiao-Qiang; Cui, Bao-Qun; Chen, Li-Hua; Jiang, Wei-Sheng; Wu, Yi-Can; Huang, Qun-Ying; Peng, Lei; Cao, Xing-Zhong; Wang, Bao-Yi; Wei, Long; Zhu, Sheng-Yun

    2014-04-01

    The synergistic effect of triple ion beams is investigated by simultaneous and sequential irradiations of gold, hydrogen and helium ions on the low activation martensitic steel (CLAM) developed in China. The depth profile measurements of the positron annihilation Doppler broadening S parameter are carried out as a function of slow-positron beam energy to examine the produced radiation damage. The synergistic effect of displacement damage and hydrogen and helium on the formation of radiation damage is clearly observed. In the preset case, this effect suppresses the radiation damage in the CLAM steel due to the helium and/or hydrogen filling of vacancy clusters.

  6. Radiation damage effects in CZT drift strip detectors

    NASA Astrophysics Data System (ADS)

    Kuvvetli, Irfan; Budtz-Joergensen, Carl; Korsbech, Uffe; Jensen, H. J.

    2003-03-01

    At DSRI, in collaboration with the cyclotron facility at Copenhagen University Hospital, we have performed a study of radiation effects exposing a 2.7 mm thick CZT drift strip detector to 30 MeV protons. The detector characteristics were evaluated after exposure to a number of dose loads in the range from 2*108 to 60*108 p+/cm2. Even for the highest dose loads, which had a dramatic effect on the spectroscopic performance, we were able to recover the detectors after an appropriate annealing procedure. The radiation damage was studied as function of depth inside the detector material. A numerical model that emulates the physical processes of the charge transport in the CZT detector was used to derive the charge trapping parameter , μτe (the product of charge mobility and trapping time) as function of dose. The analysis showed that the electron trapping increased proportional with the proton dose. The radiation contribution to the electron trapping was found to obey the following relation: (μτe)-1rad =(2.5±0.2)*10-7*Φ (V/cm2) with the proton fluence, Φ in p+/cm2. The trapping depth dependence, however, did not agree well the damage profile calculated using the standard Monte Carlo simulations, TRIM for the proton induced radiation effects. The present results suggest that proton induced nuclear reactions contribute significantly to the radiation damage. Further work will elaborate on these effects. The detector energy resolution was investigated as function of proton dose. It was found that the observed degradation is well explained by the decrease of μτe when the fluctuations of the electron path length are taken into account. The proton irradiation produced In meta stable isotopes in the CZT material. Their decay and production yield as function of depth were analyzed.

  7. Radiation damage in PVT (Polyvinyltoluene) induced by energetic ions

    NASA Astrophysics Data System (ADS)

    Torrisi, L.

    Polyvinyltoluene (PVT) is an organic polymer employed as base material for many plastic scintillators useful to detect charged particles. Radiation damage in PVT is investigated irradiating the polymer in vacuum with different ion beams (H+, He+, N+ and Ar+) as a function of their ion stopping power. The structural modifications indced in the polymer are deduced by monitoring in situ, during the ion irradiation, the molecular desorption from the polymer by a highly sensitive mass-quadrupole spectrometer. The desorbed molecules are detected in the mass range 1-100 amu and the chemical yields are measured with respect to the calibrated gas leaks. Main emitted species are H2, C2H2 and C3H5, the yields of which strongly depend on the ion stopping power. As will be discussed, the investigation of radiation damage in PVT permits to extend the results to the damage undergone by plastic scintillators during the detection of charged particles at high energy, such as protons of 10-100 MeV, an energy range useful in nuclear physics and in proton-therapy.

  8. Chemistry of radiation damage to wire chambers

    SciTech Connect

    Wise, J.

    1992-08-01

    Proportional counters are used to study aspects of radiation damage to wire chambers (wire aging). Principles of low-pressure, rf plasma chemistry are used to predict the plasma chemistry in electron avalanches (1 atm, dc). (1) Aging is studied in CF{sub 4}/iC{sub 4}H{sub 10} gas mixtures. Wire deposits are analyzed by Auger electron spectroscopy. An apparent cathode aging process resulting in loss of gain rather than in a self-sustained current is observed in CF{sub 4}-rich gases. A four-part model considering plasma polymerization of the hydrocarbon, etching of wire deposits by CF{sub 4}, acceleration of deposition processes in strongly etching environments, and reactivity of the wire surface is developed to understand anode wire aging in CF{sub 4}/iC{sub 4}H{sub 10} gases. Practical guidelines suggested by the model are discussed. (2) Data are presented to suggest that trace amounts of Freons do not affect aging rates in either dimethyl ether or Ar/C{sub 2}H{sub 6}. Apparent loss of gain is explained by attachment of primary electrons to a continuously increasing concentration of Freon 11 (CCl{sub 3}F) in the counter gas. An increase in the concentration of Freon 11 in dimethyl ether is caused by a distillation process in the gas supply bottle and is a natural consequence of the unequal volatilities of the two compounds.

  9. Effects of radiation damage on the silicon lattice

    NASA Technical Reports Server (NTRS)

    Dumas, Katherine A.; Lowry, Lynn; Russo, O. Louis

    1987-01-01

    Silicon was irradiated with both proton and electron particle beams in order to investigate changes in the structural and optical properties of the lattice as a result of the radiation damage. Lattice expansions occurred when large strain fields (+0.34 percent) developed after 1- and 3-MeV proton bombardment. The strain was a factor of three less after 1-MeV electron irradiation. Average increases of approximately 22 meV in the 3.46-eV interband energy gap and 14 meV in the Lorentz broadening parameter were measured after the electron irradiation.

  10. Genetic damage in subjects exposed to radiofrequency radiation.

    PubMed

    Verschaeve, Luc

    2009-01-01

    Despite many research efforts and public debate there is still great concern about the possible adverse effects of radiofrequency (RF) radiation on human health. This is especially due to the enormous increase of wireless mobile telephones and other telecommunication devices throughout the world. The possible genetic effects of mobile phone radiation and other sources of radiofrequencies constitute one of the major points of concern. In the past several review papers were published on laboratory investigations that were devoted to in vitro and in vivo animal (cyto)genetic studies. However, it may be assumed that some of the most important observations are those obtained from studies with individuals that were exposed to relatively high levels of radiofrequency radiation, either as a result of their occupational activity or as frequent users of radiofrequency emitting tools. In this paper the cytogenetic biomonitoring studies of RF-exposed humans are reviewed. A majority of these studies do show that RF-exposed individuals have increased frequencies of genetic damage (e.g., chromosomal aberrations) in their lymphocytes or exfoliated buccal cells. However, most of the studies, if not all, have a number of shortcomings that actually prevents any firm conclusion. Radiation dosimetry was lacking in all papers, but some of the investigations were flawed by much more severe imperfections. Large well-coordinated multidisciplinary investigations are needed in order to reach any robust conclusion. PMID:19073278

  11. Analytical modeling for gamma radiation damage on silicon photodiodes

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  12. Influence of radiation damage on xenon diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Gärtner, K.; Hlatshwayo, T. T.; van der Berg, N. G.; Thabethe, T. T.

    2014-08-01

    Diffusion of xenon in poly and single crystalline silicon carbide and the possible influence of radiation damage on it are investigated. For this purpose 360 keV xenon ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and xenon retention during isochronal and isothermal annealing up to temperatures of 1500 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by α-particle channelling. No diffusion or xenon loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature serious erosion of the implanted surface occurred, which made any analysis impossible. No diffusion or xenon loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC.

  13. The evaluation of radiation damage parameter for CVD diamond

    NASA Astrophysics Data System (ADS)

    Grilj, V.; Skukan, N.; Jakšić, M.; Pomorski, M.; Kada, W.; Kamiya, T.; Ohshima, T.

    2016-04-01

    There are a few different phenomenological approaches that aim to track the dependence of signal height in irradiated solid state detectors on the fluence of damaging particles. However, none of them are capable to provide a unique radiation hardness parameter that would reflect solely the material capability to withstand high radiation environment. To extract such a parameter for chemical vapor deposited (CVD) diamond, two different diamond detectors were irradiated with proton beams in MeV energy range and subjected afterwards to ion beam induced charge (IBIC) analysis. The change in charge collection efficiency (CCE) due to defects produced was investigated in context of a theoretical model that was developed on the basis of the adjoint method for linearization of the continuity equations of electrons and holes. Detailed modeling of measured data resulted with the first known value of the kσ product for diamond, where k represents the number of charge carriers' traps created per one simulated primary lattice vacancy and σ represents the charge carriers' capture cross section. As discussed in the text, this product could be considered as a true radiation damage parameter.

  14. Radiation Damages in Aluminum Alloy SAV-1 under Neutron Irradiation

    NASA Astrophysics Data System (ADS)

    Salikhbaev, Umar; Akhmedzhanov, Farkhad; Alikulov, Sherali; Baytelesov, Sapar; Boltabaev, Azizbek

    2016-05-01

    The aim of this work was to study the effect of neutron irradiation on the kinetics of radiation damages in the SAV-1 alloy, which belongs to the group of aluminum alloys of the ternary system Al-Mg-Si. For fast-neutron irradiation by different doses up to fluence 1019 cm-2 the SAV-1 samples were placed in one of the vertical channels of the research WWR type reactor (Tashkent). The temperature dependence of the electrical resistance of the alloy samples was investigated in the range 290 - 490 K by the four-compensation method with an error about 0.1%. The experimental results were shown that at all the temperatures the dependence of the SAV-1 alloy resistivity on neutron fluence was nonlinear. With increasing neutron fluence the deviation from linearity and the growth rate of resistivity with temperature becomes more appreciable. The observed dependences are explained by means of martensitic transformations and the radiation damages in the studied alloy under neutron irradiation. The mechanisms of radiation modification of the SAV-1 alloy structure are discussed.

  15. UV Radiation Damage and Bacterial DNA Repair Systems

    ERIC Educational Resources Information Center

    Zion, Michal; Guy, Daniel; Yarom, Ruth; Slesak, Michaela

    2006-01-01

    This paper reports on a simple hands-on laboratory procedure for high school students in studying both radiation damage and DNA repair systems in bacteria. The sensitivity to ultra-violet (UV) radiation of both "Escherichia coli" and "Serratia marcescens" is tested by radiating them for varying time periods. Two growth temperatures are used in…

  16. DNA damage and repair after high LET radiation

    NASA Astrophysics Data System (ADS)

    O'Neill, Peter; Cucinotta, Francis; Anderson, Jennifer

    Predictions from biophysical models of interactions of radiation tracks with cellular DNA indicate that clustered DNA damage sites, defined as two or more lesions formed within one or two helical turns of the DNA by passage of a single radiation track, are formed in mammalian cells. These complex DNA damage sites are regarded as a signature of ionizing radiation exposure particularly as the likelihood of clustered damage sites arising endogenously is low. For instance, it was predicted from biophysical modelling that 30-40% of low LET-induced double strand breaks (DSB), a form of clustered damage, are complex with the yield increasing to >90% for high LET radiation, consistent with the reduced reparability of DSB with increasing ionization density of the radiation. The question arises whether the increased biological effects such as mutagenesis, carcinogenesis and lethality is in part related to DNA damage complexity and/or spatial distribution of the damage sites, which may lead to small DNA fragments. With particle radiation it is also important to consider not only delta-rays which may cause clustered damaged sites and may be highly mutagenic but the non-random spatial distribution of DSB which may lead to deletions. In this overview I will concentrate on the molecular aspects of the variation of the complexity of DNA damage on radiation quality and the challenges this complexity presents the DNA damage repair pathways. I will draw on data from micro-irradiations which indicate that the repair of DSBs by non-homologous end joining is highly regulated with pathway choice and kinetics of repair dependent on the chemical complexity of the DSB. In summary the aim is to emphasis the link between the spatial distribution of energy deposition events related to the track, the molecular products formed and the consequence of damage complexity contributing to biological effects and to present some of the outstanding molecular challenges with particle radiation.

  17. The energy dependence of refractory metals and alloys radiation damageability

    NASA Astrophysics Data System (ADS)

    Mukashev, K. M.; Umarov, F. F.

    2015-04-01

    In this work the systematical investigation of the radiation defects distribution profile energy dependence in three different materials - tantalum, molybdenum and 10X18H10T-VD stainless steel irradiated by high energy protons has been performed. It has been shown that in stainless steel and tantalum, independently of proton energy, the vacancy complexes related by configuration appear which are described by the slightly expressed elastic channel. The defects are recovered in one annealing stage with different migration activation energy. At the same time the molybdenum radiation damageability is composed of two components in each of which its specified defects formation mechanism takes action. For high energy protons the inelastic channel of interaction is the basic and subcascades appearance is created by primary knocked-on atoms of considerable energies. For low energy protons the processes of elastic interaction with lattice atoms and atomic hydrogen in the end of run creation are major.

  18. Radiation Damage to Artemia Cysts:Effects of Water Vapor.

    PubMed

    Snipes, W C; Gordy, W

    1963-10-25

    Water vapor altered the form and greatly increased the rate of decay of the electron-spin resonance pattern of long-lived free radicals obtained upon gamma irradiation of Artemia salina cysts ( brine shrimp eggs). These results, combined with data on radiation survival, indicate that the water vapor protects the cysts from radiation damage, or heals the damage. They also indicate that water protects the cysts from the effect of oxygen by neutralizing the radiation-induced free radicals before they can interact with oxygen to produce irreversible damage. PMID:17748168

  19. Annealing radiation damaged silicon solar cells with a copper halide laser

    NASA Technical Reports Server (NTRS)

    Pivirotto, T. J.

    1980-01-01

    The use of a multiply pulsed copper halide laser to significantly anneal out the damage to silicon solar cells caused by a simulated space radiation environment is investigated. Preliminary experiments demonstrate that the amount of damage can be decreased by 41% as measured by the maximum power generated.

  20. An Experimental Investigation of Damage Resistances and Damage Tolerance of Composite Materials

    NASA Technical Reports Server (NTRS)

    Prabhakaran, R.

    2003-01-01

    The project included three lines of investigation, aimed at a better understanding of the damage resistance and damage tolerance of pultruded composites. The three lines of investigation were: (i) measurement of permanent dent depth after transverse indentation at different load levels, and correlation with other damage parameters such as damage area (from x-radiography) and back surface crack length, (ii) estimation of point stress and average stress characteristic dimensions corresponding to measured damage parameters, and (iii) an attempt to measure the damage area by a reflection photoelastic technique. All the three lines of investigation were pursued.

  1. Computer simulation of radiation damage in gallium arsenide

    NASA Technical Reports Server (NTRS)

    Stith, John J.; Davenport, James C.; Copeland, Randolph L.

    1989-01-01

    A version of the binary-collision simulation code MARLOWE was used to study the spatial characteristics of radiation damage in proton and electron irradiated gallium arsenide. Comparisons made with the experimental results proved to be encouraging.

  2. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Garlick, G. F. J.

    1987-01-01

    High-efficiency gallium arsenide cells, made by the liquid epitaxy method (LPE), have been irradiated with 1-MeV electrons up to fluences of 10 to the 16th e/sq cm. Measurements have been made of cell spectral response and dark and light-excited current-voltage characteristics and analyzed using computer-based models to determine underlying parameters such as damage coefficients. It is possible to use spectral response to sort out damage effects in the different cell component layers. Damage coefficients are similar to other reported in the literature for the emitter and buffer (base). However, there is also a damage effect in the window layer and possibly at the window emitter interface similar to that found for proton-irradiated liquid-phase epitaxy-grown cells. Depletion layer recombination is found to be less than theoretically expected at high fluence.

  3. 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.

  4. Dynamic Optical Investigations of Hypervelocity Impact Damage

    NASA Astrophysics Data System (ADS)

    Lamberson, Leslie Elise

    One of the prominent threats in the endeavor to develop next-generation space assets is the risk of space debris impact in earth's orbit and micrometeoroid impact damage in near-earth orbit and deep space. To date, there is no study available which concentrates on the analysis of dynamic crack growth from hypervelocity impacts on such structures, resulting in their eventual catastrophic degradation. Experiments conducted using a unique two-stage light-gas gun facility have examined the in situ dynamic fracture of brittle polymers subjected to this high-energy-density event. Optical techniques of caustics and photoelasticity, combined with high-speed photography up to 100 million frames per second, analyze crack growth behavior of Mylar and Homalite 100 thin plates after impact by a 1.8 mm diameter nylon 6-6 right cylindrical slug at velocities ranging from 3 to 7 km/s (7000--15500 mph). Crack speeds in both polymers averaged between 0.2 and 0.47 cR, the Rayleigh wave speed (450--1000 mph). Shadow spots and surrounding caustics reveal time histories of the dynamic stress intensity factor, as well as the energy release rate ahead of the mode-I, or opening, crack tips. Results indicate that even under extreme impact conditions of out of-plane loading, highly localized heating, and energetic impact phenomena involving plasma formation and ejecta, the dynamic fracture process occurs during a deformation regime dominated by in-plane loading. These findings imply that the reliability of impacted, thin-walled, plate and shell space structures, idealized by the experimental configuration investigated, can be predicted by the well defined principles of classical dynamic fracture mechanics.

  5. Radiation damage of gallium arsenide production cells

    NASA Technical Reports Server (NTRS)

    Mardesich, N.; Joslin, D.; Garlick, J.; Lillington, D.; Gillanders, M.; Cavicchi, B.; Scott-Monck, J.; Kachare, R.; Anspaugh, B.

    1987-01-01

    High efficiency liquid phase epitaxy (LPE) gallium arsenide cells were irradiated with 1 Mev electrons up to fluences of 1 times 10 to the 16th power cm-2. Measurements of spectral response and dark and illuminated I-V data were made at each fluence and then, using computer codes, the experimental data was fitted to gallium arsenide cell models. In this way it was possible to determine the extent of the damage, and hence damage coefficients in both the emitter and base of the cell.

  6. Space Shuttle STS-1 SRB damage investigation

    NASA Technical Reports Server (NTRS)

    Nevins, C. D.

    1982-01-01

    The physical damage incurred by the solid rocket boosters during reentry on the initial space shuttle flight raised the question of whether the hardware, as designed, would yield the low cost per flight desired. The damage was quantified, the cause determined and specific design changes recommended which would preclude recurrence. Flight data, postflight analyses, and laboratory hardware examinations were used. The resultant findings pointed to two principal causes: failure of the aft skirt thermal curtain at the onset of reentry aerodynamic heating, and overloading of the aft shirt stiffening rings during water impact. Design changes were recommended on both the thermal curtain and the aft skirt structural members to prevent similar damage on future missions.

  7. Electronic effects in high-energy radiation damage in tungsten

    DOE PAGESBeta

    Zarkadoula, Eva; Duffy, Dorothy M.; Nordlund, Kai; Seaton, M. A.; Todorov, I. T.; Weber, William J.; Trachenko, Kostya

    2015-01-01

    Even though the effects of the electronic excitations during high-energy radiation damage processes are not currently understood, it is shown that their role in the interaction of radiation with matter is important. We perform molecular dynamics simulations of high-energy collision cascades in bcc-tungsten using the coupled two-temperature molecular dynamics (2T-MD) model that incorporates both the effects of electronic stopping and electron–phonon interaction. We compare the combination of these effects on the induced damage with only the effect of electronic stopping, and conclude in several novel insights. In the 2T-MD model, the electron–phonon coupling results in less damage production in themore » molten region and in faster relaxation of the damage at short times. We show these two effects lead to a significantly smaller amount of the final damage at longer times.« less

  8. Electronic effects in high-energy radiation damage in tungsten

    SciTech Connect

    Zarkadoula, Eva; Duffy, Dorothy M.; Nordlund, Kai; Seaton, M. A.; Todorov, I. T.; Weber, William J.; Trachenko, Kostya

    2015-01-01

    Even though the effects of the electronic excitations during high-energy radiation damage processes are not currently understood, it is shown that their role in the interaction of radiation with matter is important. We perform molecular dynamics simulations of high-energy collision cascades in bcc-tungsten using the coupled two-temperature molecular dynamics (2T-MD) model that incorporates both the effects of electronic stopping and electron–phonon interaction. We compare the combination of these effects on the induced damage with only the effect of electronic stopping, and conclude in several novel insights. In the 2T-MD model, the electron–phonon coupling results in less damage production in the molten region and in faster relaxation of the damage at short times. We show these two effects lead to a significantly smaller amount of the final damage at longer times.

  9. Radiation damage to scintillator in the D0 luminosity monitor

    SciTech Connect

    Casey, Brendan; DeVaughan, Kayle; Enari, Yuji; Partridge, Richard; Yacoob, Sahal; /Northwestern U.

    2006-12-01

    We report the result of evaluating radiation damage to Bicron BC408 plastic scintillator used in the D0 Luminosity Monitor during Run IIa. The Luminosity Monitor provides pseudo-rapidity coverage over the range 2.7 < |{eta}| < 4.4, with the radiation dose in Run IIa estimated to be 0.5 MRad for the region closest to the beams. We find the light yield is degraded by 10-15% due to radiation damage by comparing new and old scintillator in four observables: (1) visual inspection, (2) optical transmittance, (3) response to the radioactive source of {sup 90}Sr and (4) light yield for cosmic rays.

  10. Radiation-induced DNA damage and chromatin structure

    NASA Technical Reports Server (NTRS)

    Rydberg, B.; Chatterjee, A. (Principal Investigator)

    2001-01-01

    DNA lesions induced by ionizing radiation in cells are clustered and not randomly distributed. For low linear energy transfer (LET) radiation this clustering occurs mainly on the small scales of DNA molecules and nucleosomes. For example, experimental evidence suggests that both strands of DNA on the nucleosomal surface can be damaged in single events and that this damage occurs with a 10-bp modulation because of protection by histones. For high LET radiation, clustering also occurs on a larger scale and depends on chromatin organization. A particularly significant clustering occurs when an ionizing particle traverses the 30 nm chromatin fiber with generation of heavily damaged DNA regions with an average size of about 2 kbp. On an even larger scale, high LET radiation can produce several DNA double-strand breaks in closer proximity than expected from randomness. It is suggested that this increases the probability of misrejoining of DNA ends and generation of lethal chromosome aberrations.

  11. Space solar cells - High efficiency and radiation damage

    NASA Technical Reports Server (NTRS)

    Brandhorst, H. W., Jr.; Bernatowicz, D. T.

    1980-01-01

    The proceedings of the Third Solar Cell High Efficiency and Radiation Damage Meeting are outlined. The topics covered included high efficiency silicon solar cells, silicon solar cell radiation damage, GaAs solar cell performance, and 30 percent conversion devices. The study of radiation damage from a fundamental defect-centered basis is discussed and evaluated as a focus of future work. 18% AM0 efficiency and 0.7 V open-circuit voltages are designated as achievable goals for silicon solar cells, and the potential for 30% AM0 efficiencies from monolithic tandem cell designs without sunlight concentration is noted. In addition to its potential for 20% AM0 efficiencies, the GaAs cell offers the possibility of a radiation-insensitive power supply when operated at temperatures near 200 C.

  12. Effect of radiation-induced damage on deuterium retention in tungsten, tungsten coatings and Eurofer

    NASA Astrophysics Data System (ADS)

    Ogorodnikova, O. V.; Sugiyama, K.

    2013-11-01

    An influence of radiation-induced damage on hydrogen isotope retention and transport in a bulk tungsten (W), dense nano-structured W coatings and Eurofer was investigated under well-defined laboratory conditions. Radiation-induced defects in W materials and Eurofer were created by irradiation with 20 MeV W ions. Following the damage production, samples were exposed to low-energy deuterium plasma. The deuterium (D) retention in each sample was subsequently measured by nuclear reaction analysis (NRA) for the depth profiling up to 6 μm. It was shown that the D retention at radiation-induced damage is almost equivalent for different W grades after irradiation at high enough fluence. The kinetic of D migration and trapping in damaged area as well as recovery of radiation-induced damage were investigated by loading at different temperatures. It was shown that deuterium retention in tungsten in fusion environment will be dominated by radiation-induced effect in a wide range of investigated temperatures, namely, from room temperature to 1100 K. Whereas displacement damage produced in Eurofer has less pronounced effect on the deuterium accumulation.

  13. Spectrum of complex DNA damages depends on the incident radiation

    NASA Astrophysics Data System (ADS)

    Hada, M.; Sutherland, B.

    Ionizing radiation induces clustered DNA damages in DNA-two or more abasic sites oxidized bases and strand breaks on opposite DNA strands within a few helical turns Clustered damages are considered to be difficult to repair and therefore potentially lethal and mutagenic damages Although induction of single strand breaks and isolated lesions has been studied extensively little is known of factors affecting induction of clusters other than double strand breaks DSB The aim of the present study was to determine whether the type of incident radiation could affect yield or spectra of specific clusters Genomic T7 DNA a simple 40 kbp linear blunt-ended molecule was irradiated in non-scavenging buffer conditions with Fe 970 MeV n Ti 980 MeV n C 293 MeV n Si 586 MeV n ions or protons 1 GeV n at the NASA Space Radiation Laboratory or with 100 kVp X-rays Irradiated DNA was treated with homogeneous Fpg or Nfo proteins or without enzyme treatment for DSB quantitation then electrophoresed in neutral agarose gels DSB Fpg-OxyPurine clusters and Nfo-Abasic clusters were quantified by number average length analysis The results show that the yields of all these complex damages depend on the incident radiation Although LETs are similar protons induced twice as many DSBs than did X-rays Further the spectrum of damage also depends on the radiation The yield damage Mbp Gy of all damages decreased with increasing linear energy transfer LET of the radiation The relative frequencies of DSBs to Abasic- and OxyBase clusters were higher

  14. Radiation-damaged tyrosinase molecules are inactive

    SciTech Connect

    Kempner, E.S.; Miller, J.H.

    1989-01-01

    Target analysis of radiation inactivation of mushroom tyrosinase yields different target sizes for diphenoloxidase and monophenoloxidase activities, which correspond to the subunits H and HL2 (or HL), respectively. After gel electrophoresis of irradiated samples, all diphenoloxidase activity is observed at the same position as seen in the original material. Radiolytic fragments contain no detectable activity, consistent with a fundamental assumption of target theory.

  15. Damage-tolerant nanotwinned metals with nanovoids under radiation environments

    PubMed Central

    Chen, Y.; Yu, K Y.; Liu, Y.; Shao, S.; Wang, H.; Kirk, M. A.; Wang, J.; Zhang, X.

    2015-01-01

    Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from high density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials. PMID:25906997

  16. Damage-tolerant nanotwinned metals with nanovoids under radiation environments.

    PubMed

    Chen, Y; Yu, K Y; Liu, Y; Shao, S; Wang, H; Kirk, M A; Wang, J; Zhang, X

    2015-01-01

    Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from high density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials. PMID:25906997

  17. Damage-tolerant nanotwinned metals with nanovoids under radiation environments

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Yu, K. Y.; Liu, Y.; Shao, S.; Wang, H.; Kirk, M. A.; Wang, J.; Zhang, X.

    2015-04-01

    Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from high density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials.

  18. Damage-tolerant nanotwinned metals with nanovoids under radiation environments

    DOE PAGESBeta

    Chen, Y.; Yu, K. Y.; Liu, Y.; Shao, S.; Wang, H.; Kirk, M. A.; Wang, J.; Zhang, X.

    2015-04-24

    Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from highmore » density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials.« less

  19. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D.W.; Bennett, B.L.; Cockroft, N.J.

    1998-09-08

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal. 5 figs.

  20. Minimizing radiation damage in nonlinear optical crystals

    DOEpatents

    Cooke, D. Wayne; Bennett, Bryan L.; Cockroft, Nigel J.

    1998-01-01

    Methods are disclosed for minimizing laser induced damage to nonlinear crystals, such as KTP crystals, involving various means for electrically grounding the crystals in order to diffuse electrical discharges within the crystals caused by the incident laser beam. In certain embodiments, electrically conductive material is deposited onto or into surfaces of the nonlinear crystals and the electrically conductive surfaces are connected to an electrical ground. To minimize electrical discharges on crystal surfaces that are not covered by the grounded electrically conductive material, a vacuum may be created around the nonlinear crystal.

  1. DNA damage in cells exhibiting radiation-induced genomic instability

    DOE PAGESBeta

    Keszenman, Deborah J.; Kolodiuk, Lucia; Baulch, Janet E.

    2015-02-22

    Cells exhibiting radiation induced genomic instability exhibit varied spectra of genetic and chromosomal aberrations. Even so, oxidative stress remains a common theme in the initiation and/or perpetuation of this phenomenon. Isolated oxidatively modified bases, abasic sites, DNA single strand breaks and clustered DNA damage are induced in normal mammalian cultured cells and tissues due to endogenous reactive oxygen species generated during normal cellular metabolism in an aerobic environment. While sparse DNA damage may be easily repaired, clustered DNA damage may lead to persistent cytotoxic or mutagenic events that can lead to genomic instability. In this study, we tested the hypothesismore » that DNA damage signatures characterised by altered levels of endogenous, potentially mutagenic, types of DNA damage and chromosomal breakage are related to radiation-induced genomic instability and persistent oxidative stress phenotypes observed in the chromosomally unstable progeny of irradiated cells. The measurement of oxypurine, oxypyrimidine and abasic site endogenous DNA damage showed differences in non-double-strand breaks (DSB) clusters among the three of the four unstable clones evaluated as compared to genomically stable clones and the parental cell line. These three unstable clones also had increased levels of DSB clusters. The results of this study demonstrate that each unstable cell line has a unique spectrum of persistent damage and lead us to speculate that alterations in DNA damage signaling and repair may be related to the perpetuation of genomic instability.« less

  2. DNA damage in cells exhibiting radiation-induced genomic instability

    SciTech Connect

    Keszenman, Deborah J.; Kolodiuk, Lucia; Baulch, Janet E.

    2015-02-22

    Cells exhibiting radiation induced genomic instability exhibit varied spectra of genetic and chromosomal aberrations. Even so, oxidative stress remains a common theme in the initiation and/or perpetuation of this phenomenon. Isolated oxidatively modified bases, abasic sites, DNA single strand breaks and clustered DNA damage are induced in normal mammalian cultured cells and tissues due to endogenous reactive oxygen species generated during normal cellular metabolism in an aerobic environment. While sparse DNA damage may be easily repaired, clustered DNA damage may lead to persistent cytotoxic or mutagenic events that can lead to genomic instability. In this study, we tested the hypothesis that DNA damage signatures characterised by altered levels of endogenous, potentially mutagenic, types of DNA damage and chromosomal breakage are related to radiation-induced genomic instability and persistent oxidative stress phenotypes observed in the chromosomally unstable progeny of irradiated cells. The measurement of oxypurine, oxypyrimidine and abasic site endogenous DNA damage showed differences in non-double-strand breaks (DSB) clusters among the three of the four unstable clones evaluated as compared to genomically stable clones and the parental cell line. These three unstable clones also had increased levels of DSB clusters. The results of this study demonstrate that each unstable cell line has a unique spectrum of persistent damage and lead us to speculate that alterations in DNA damage signaling and repair may be related to the perpetuation of genomic instability.

  3. The radiation damage of crystalline silicon PN diode in tritium beta-voltaic battery.

    PubMed

    Lei, Yisong; Yang, Yuqing; Liu, Yebing; Li, Hao; Wang, Guanquan; Hu, Rui; Xiong, Xiaoling; Luo, Shunzhong

    2014-08-01

    A tritium beta-voltaic battery using a crystalline silicon convertor composed of (100)Si/SiO2/Si3N4 film degrades remarkably with radiation from a high intensity titanium tritide film. Simulation and experiments were carried out to investigate the main factor causing the degradation. The radiation damages mainly comes from the x-ray emitted from the titanium tritide film and beta particle can relieve the damages. The x-ray radiation induced positive charges in the SiO2 film destroying the output property of the PN diode with the induction of an electric field. PMID:24751350

  4. Opportunities for nutritional amelioration of radiation-induced cellular damage.

    PubMed

    Turner, Nancy D; Braby, Leslie A; Ford, John; Lupton, Joanne R

    2002-10-01

    The closed environment and limited evasive capabilities inherent in space flight cause astronauts to be exposed to many potential harmful agents (chemical contaminants in the environment and cosmic radiation exposure). Current power systems used to achieve space flight are prohibitively expensive for supporting the weight requirements to fully shield astronauts from cosmic radiation. Therefore, radiation poses a major, currently unresolvable risk for astronauts, especially for long-duration space flights. The major detrimental radiation effects that are of primary concern for long-duration space flights are damage to the lens of the eye, damage to the immune system, damage to the central nervous system, and cancer. In addition to the direct damage to biological molecules in cells, radiation exposure induces oxidative damage. Many natural antioxidants, whether consumed before or after radiation exposure, are able to confer some level of radioprotection. In addition to achieving beneficial effects from long-known antioxidants such as vitamins E and C and folic acid, some protection is conferred by several recently discovered antioxidant molecules, such as flavonoids, epigallocatechin, and other polyphenols. Somewhat counterintuitive is the protection provided by diets containing elevated levels of omega-3 polyunsaturated fatty acids, considering they are thought to be prone to peroxidation. Even with the information we have at our disposal, it will be difficult to predict the types of dietary modifications that can best reduce the risk of radiation exposure to astronauts, those living on Earth, or those enduring diagnostic or therapeutic radiation exposure. Much more work must be done in humans, whether on Earth or, preferably, in space, before we are able to make concrete recommendations. PMID:12361786

  5. Opportunities for nutritional amelioration of radiation-induced cellular damage

    NASA Technical Reports Server (NTRS)

    Turner, Nancy D.; Braby, Leslie A.; Ford, John; Lupton, Joanne R.

    2002-01-01

    The closed environment and limited evasive capabilities inherent in space flight cause astronauts to be exposed to many potential harmful agents (chemical contaminants in the environment and cosmic radiation exposure). Current power systems used to achieve space flight are prohibitively expensive for supporting the weight requirements to fully shield astronauts from cosmic radiation. Therefore, radiation poses a major, currently unresolvable risk for astronauts, especially for long-duration space flights. The major detrimental radiation effects that are of primary concern for long-duration space flights are damage to the lens of the eye, damage to the immune system, damage to the central nervous system, and cancer. In addition to the direct damage to biological molecules in cells, radiation exposure induces oxidative damage. Many natural antioxidants, whether consumed before or after radiation exposure, are able to confer some level of radioprotection. In addition to achieving beneficial effects from long-known antioxidants such as vitamins E and C and folic acid, some protection is conferred by several recently discovered antioxidant molecules, such as flavonoids, epigallocatechin, and other polyphenols. Somewhat counterintuitive is the protection provided by diets containing elevated levels of omega-3 polyunsaturated fatty acids, considering they are thought to be prone to peroxidation. Even with the information we have at our disposal, it will be difficult to predict the types of dietary modifications that can best reduce the risk of radiation exposure to astronauts, those living on Earth, or those enduring diagnostic or therapeutic radiation exposure. Much more work must be done in humans, whether on Earth or, preferably, in space, before we are able to make concrete recommendations.

  6. Influence of radiation damage on krypton diffusion in silicon carbide

    NASA Astrophysics Data System (ADS)

    Friedland, E.; Hlatshwayo, T. T.; van der Berg, N. G.; Mabena, M. C.

    2015-07-01

    Diffusion of krypton in poly and single crystalline silicon carbide is investigated and compared with the previously obtained results for xenon, which pointed to a different diffusion mechanism than observed for chemically active elements. For this purpose 360 keV krypton ions were implanted in commercial 6H-SiC and CVD-SiC wafers at room temperature, 350 °C and 600 °C. Width broadening of the implantation profiles and krypton retention during isochronal and isothermal annealing up to temperatures of 1400 °C was determined by RBS-analysis, whilst in the case of 6H-SiC damage profiles were simultaneously obtained by α-particle channeling. Little diffusion and no krypton loss was detected in the initially amorphized and eventually recrystallized surface layer of cold implanted 6H-SiC during annealing up to 1200 °C. Above that temperature thermal etching of the implanted surface became increasingly important. No diffusion or krypton loss is detected in the hot implanted 6H-SiC samples during annealing up to 1400 °C. Radiation damage dependent grain boundary diffusion is observed at 1300 °C in CVD-SiC. The results seem to indicate, that the chemically inert noble gas atoms do not form defect-impurity complexes, which strongly influence the diffusion behavior of other diffusors in silicon carbide.

  7. High-energy radiation damage in zirconia: modeling results

    SciTech Connect

    Zarkadoula, Eva; Devanathan, Ram; Weber, William J.; Seaton, Michael; Todorov, Ilian; Nordlund, Kai; Dove, Martin T.; Trachenko, Kostya

    2014-02-28

    Zirconia has been viewed as a material of exceptional resistance to amorphization by radiation damage, and was consequently proposed as a candidate to immobilize nuclear waste and serve as a nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with the account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely disjoint from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  8. High-energy radiation damage in zirconia: Modeling results

    NASA Astrophysics Data System (ADS)

    Zarkadoula, E.; Devanathan, R.; Weber, W. J.; Seaton, M. A.; Todorov, I. T.; Nordlund, K.; Dove, M. T.; Trachenko, K.

    2014-02-01

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  9. High-energy radiation damage in zirconia: modeling results

    SciTech Connect

    Zarkadoula, Evangelia; Devanathan, Ram; Weber, William J; Seaton, M; Todorov, I T; Nordlund, Kai; Dove, Martin T; Trachenko, Kostya

    2014-01-01

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1-0.5 MeV energies with account of electronic energy losses. We nd that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  10. High-energy radiation damage in zirconia: Modeling results

    SciTech Connect

    Zarkadoula, E.; Devanathan, R.; Weber, W. J.; Seaton, M. A.; Todorov, I. T.; Nordlund, K.; Dove, M. T.; Trachenko, K.

    2014-02-28

    Zirconia is viewed as a material of exceptional resistance to amorphization by radiation damage, and consequently proposed as a candidate to immobilize nuclear waste and serve as an inert nuclear fuel matrix. Here, we perform molecular dynamics simulations of radiation damage in zirconia in the range of 0.1–0.5 MeV energies with account of electronic energy losses. We find that the lack of amorphizability co-exists with a large number of point defects and their clusters. These, importantly, are largely isolated from each other and therefore represent a dilute damage that does not result in the loss of long-range structural coherence and amorphization. We document the nature of these defects in detail, including their sizes, distribution, and morphology, and discuss practical implications of using zirconia in intense radiation environments.

  11. Studying Radiation Damage in Structural Materials by Using Ion Accelerators

    NASA Astrophysics Data System (ADS)

    Hosemann, Peter

    2011-02-01

    Radiation damage in structural materials is of major concern and a limiting factor for a wide range of engineering and scientific applications, including nuclear power production, medical applications, or components for scientific radiation sources. The usefulness of these applications is largely limited by the damage a material can sustain in the extreme environments of radiation, temperature, stress, and fatigue, over long periods of time. Although a wide range of materials has been extensively studied in nuclear reactors and neutron spallation sources since the beginning of the nuclear age, ion beam irradiations using particle accelerators are a more cost-effective alternative to study radiation damage in materials in a rather short period of time, allowing researchers to gain fundamental insights into the damage processes and to estimate the property changes due to irradiation. However, the comparison of results gained from ion beam irradiation, large-scale neutron irradiation, and a variety of experimental setups is not straightforward, and several effects have to be taken into account. It is the intention of this article to introduce the reader to the basic phenomena taking place and to point out the differences between classic reactor irradiations and ion irradiations. It will also provide an assessment of how accelerator-based ion beam irradiation is used today to gain insight into the damage in structural materials for large-scale engineering applications.

  12. Raman study of radiation-damaged zircon under hydrostatic compression

    NASA Astrophysics Data System (ADS)

    Nasdala, Lutz; Miletich, Ronald; Ruschel, Katja; Váczi, Tamás

    2008-12-01

    Pressure-induced changes of Raman band parameters of four natural, gem-quality zircon samples with different degrees of self-irradiation damage, and synthetic ZrSiO4 without radiation damage, have been studied under hydrostatic compression in a diamond anvil cell up to ~10 GPa. Radiation-damaged zircon shows similar up-shifts of internal SiO4 stretching modes at elevated pressures as non-damaged ZrSiO4. Only minor changes of band-widths were observed in all cases. This makes it possible to estimate the degree of radiation damage from the width of the ν3(SiO4) band of zircon inclusions in situ, almost independent from potential “fossilized pressures” or compressive strain acting on the inclusions. An application is the non-destructive analysis of gemstones such as corundum or spinel: broadened Raman bands are a reliable indicator of self-irradiation damage in zircon inclusions, whose presence allows one to exclude artificial color enhancement by high-temperature treatment of the specimen.

  13. ANL/WSU radiation damage studies

    SciTech Connect

    Jankowski, D.; Lopiano, D.; Proudfoot, J.; Underwood, D.; Miles, L.; Neidiger, J.; Tripard, G.

    1993-12-31

    We report preliminary results for the radiation hardness of (polystryrene) plastic scintillator stacks using a spectrum of energy hardened neutrons from a MARK-III TRIGA reactor. The total dose ranged from 100 KRad to 3MRad. The corresponding fluence was 3.8 {times} 10{sup 13} to 3.8 {times} 10{sup 14} (n/cm/cm) with the gamma contribution on the order 2--3% (of fluence). The measurements used Li-6, Li-7 Thermo-luminescence dosimeters. Radiochromic/GaF- Chromic film, and activated foils simultaneously allowing an inter-comparison of these various methods of dosimetry.

  14. Proton radiation damage in optical filter glass

    NASA Technical Reports Server (NTRS)

    Grillot, Patrick N.; Rosenberg, William J.

    1989-01-01

    Samples of Schott BG-39 and Hoya CM-500 blue-green filter glass were subjected to proton radiation to determine their acceptability for spaceflight. Initial testing done with 2.7 MeV protons showed negligible change in optical transmittance with doses as high as 5.2 x 10 to the 14th protons per sq cm. Irradiation with protons of energy up to 63 MeV caused a significant reduction in transmittance in the Schott samples at doses of 5.3 x 10 to the 12th protons per sq cm, while negligible change occurred in the Hoya samples.

  15. Multiscale approach to the physics of radiation damage with ions

    SciTech Connect

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2013-04-19

    We review a multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales. We briefly overview its history and present the current stage of its development. The differences of the multiscale approach from other methods of understanding and assessment of radiation damage are discussed as well as its relationship to other branches of physics, chemistry and biology.

  16. Computer simulation radiation damages in condensed matters

    NASA Astrophysics Data System (ADS)

    Kupchishin, A. I.; Kupchishin, A. A.; Voronova, N. A.; Kirdyashkin, V. I.; Gyngazov, V. A.

    2016-02-01

    As part of the cascade-probability method were calculated the energy spectra of primary knocked-out atoms and the concentration of radiation-induced defects in a number of metals irradiated by electrons. As follows from the formulas, the number of Frenkel pairs at a given depth depends on three variables having certain physical meaning: firstly, Cd (Ea h) is proportional to the average energy of the considered depth of the PKA (if it is higher, than the greater number of atoms it will displace); secondly is inversely proportional to the path length λ2 for the formation of the PKA (if λ1 is higher than is the smaller the probability of interaction) and thirdly is inversely proportional to Ed. In this case calculations are in satisfactory agreement with the experimental data (for example, copper and aluminum).

  17. Gallium Arsenide solar cell radiation damage experiment

    NASA Technical Reports Server (NTRS)

    Maurer, R. H.; Kinnison, J. D.; Herbert, G. A.; Meulenberg, A.

    1991-01-01

    Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment.

  18. Research progress in radiation detectors, pattern recognition programs, and radiation damage determination in DNA

    NASA Technical Reports Server (NTRS)

    Baily, N. A.

    1973-01-01

    The radiological implications of statistical variations in energy deposition by ionizing radiation were investigated in the conduct of the following experiments: (1) study of the production of secondary particles generated by the passage of the primary radiation through bone and muscle; (2) the study of the ratio of nonreparable to reparable damage in DNA as a function of different energy deposition patterns generated by X rays versus heavy fast charged particles; (3) the use of electronic radiography systems for direct fluoroscopic tomography and for the synthesis of multiple planes and; (4) the determination of the characteristics of systems response to split fields having different contrast levels, and of minimum detectable contrast levels between the halves under realistic clinical situations.

  19. Radiation damage studies of silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Bohn, P.; Clough, A.; Hazen, E.; Heering, A.; Rohlf, J.; Freeman, J.; Los, S.; Cascio, E.; Kuleshov, S.; Musienko, Y.; Piemonte, C.

    2009-01-01

    We report on the measurement of the radiation hardness of silicon photomultipliers (SiPMs) manufactured by Fondazione Bruno Kessler in Italy (1 and 6.2 mm2), Center of Perspective Technology and Apparatus in Russia (1 and 4.4 mm2), and Hamamatsu Corporation in Japan (1 mm2). The SiPMs were irradiated using a beam of 212 MeV protons at Massachusetts General Hospital, receiving fluences of up to 3×1010 protons per cm2 with the SiPMs at operating voltage. Leakage currents were read continuously during the irradiation. The delivery of the protons was paused periodically to record scope traces in response to calibrated light pulses to monitor the gains, photon detection efficiencies, and dark counts of the SiPMs. The leakage current and dark noise are found to increase with fluence. The leakage current is found to be proportional to the mean square deviation of the noise distribution, indicating the dark counts are due to increased random individual pixel activation, while SiPMs remain fully functional as photon detectors. The SiPMs are found to anneal at room temperature with a reduction in the leakage current by a factor of 2 in about 100 days.

  20. Radiation damage aspects of the chernobyl accident

    NASA Astrophysics Data System (ADS)

    Parmentier, N.; Nenot, J. C.

    During the night of 25 to 26 April 1986, the most severe nuclear accident occurred at the Chernobyl power station, about 150km north of Kiev, in the Ukraine. It resulted in the irradiation of 237 workers at dose levels justifying medical care. The most severe cases (115) were hospitalized in Moscow, with 20 patients with doses higher than 6 Gy. In most cases, the treatment was classical, based on transfusion of red cells and platelets, and heavy supportive therapy. For 19 patients with severe aplasia, transplantations of bone marrow (13) or foetal liver (6) were decided. Of these patients only one survived, which justifies the statement from U.S.S.R. physicians: after an accident the indications of grafting are limited and its risks may not justify its use. Most of the complications were related to radiation burns which involved 56 victims and resulted in fatal outcomes in at least 19 patients. The population was evacuated from a 30 km zone around the site; based on direct measurements and calculations, the collective dose was evaluated at 1.6 × 10 4 man Sv, with an individual average lower than 250 mSv. The European part of U.S.S.R. with 75 million persons is supposed to have received a collective dose likely to increase the natural mortality by less than 0.1%. The numbers with cancer in the Northern Hemisphere might increase by 0.004% over the next 50 years.

  1. On the Use of SRIM for Computing Radiation Damage Exposure

    SciTech Connect

    Stoller, Roger E.; Toloczko, Mychailo B.; Was, Gary S.; Certain, Alicia G.; Dwaraknath, S.; Garner, Frank A.

    2013-09-01

    The SRIM (formerly TRIM) Monte Carlo simulation code is widely used to compute a number of parameters relevant to ion beam implantation and ion beam processing of materials. It also has the capability to compute a common radiation damage exposure unit known as atomic displacements per atom (dpa). Since dpa is a standard measure of primary radiation damage production, most researchers who employ ion beams as a tool for inducing radiation damage in materials use SRIM to determine the dpa associated with their irradiations. The use of SRIM for this purpose has been evaluated and comparisons have been made with an internationally-recognized standard definition of dpa, as well as more detailed atomistic simulations of atomic displacement cascades. Differences between the standard and SRIM-based dpa are discussed and recommendations for future usage of SRIM in radiation damage studies are made. In particular, it is recommended that when direct comparisons between ion and neutron data are intended, the Kinchin-Pease option of SRIM should be selected.

  2. Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

    SciTech Connect

    Benko', Klara; Pintye, Eva; Szabo, Boglarka; Geresi, Krisztina; Megyeri, Attila; Benko, Ilona

    2008-12-08

    To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of {gamma}--irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD{sub 50} values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

  3. On the use of SRIM for computing radiation damage exposure

    NASA Astrophysics Data System (ADS)

    Stoller, R. E.; Toloczko, M. B.; Was, G. S.; Certain, A. G.; Dwaraknath, S.; Garner, F. A.

    2013-09-01

    The SRIM (formerly TRIM) Monte Carlo simulation code is widely used to compute a number of parameters relevant to ion beam implantation and ion beam processing of materials. It also has the capability to compute a common radiation damage exposure unit known as atomic displacements per atom (dpa). Since dpa is a standard measure of primary radiation damage production, most researchers who employ ion beams as a tool for inducing radiation damage in materials use SRIM to determine the dpa associated with their irradiations. The use of SRIM for this purpose has been evaluated and comparisons have been made with an internationally-recognized standard definition of dpa, as well as more detailed atomistic simulations of atomic displacement cascades. Differences between the standard and SRIM-based dpa are discussed and recommendations for future usage of SRIM in radiation damage studies are made. In particular, it is recommended that when direct comparisons between ion and neutron data are intended, the Kinchin-Pease option of SRIM should be selected.

  4. Effect of Rosiglitazone on Radiation Damage in Bone Marrow Hemopoiesis

    NASA Astrophysics Data System (ADS)

    Benkő, Klára; Pintye, Éva; Szabó, Boglárka; Géresi, Krisztina; Megyeri, Attila; Benkő, Ilona

    2008-12-01

    To study radiobiological effects and drugs, which can modify radiation injury, has an importance if we would like to avoid harmful effects of radiation due to emergency situations or treat patients with malignant diseases by radiotherapy. During the long treatment schedules patients may be treated by not only anticancer but many other drugs because of accompanying diseases. These drugs may also modify radiobiological effects. Rosiglitazone pre-treatment proved to be myeloprotective and accelerated recovery of 5-fluorouracil-damaged bone marrow in our previous experiments. Our new studies are designed to evaluate whether rosiglitazone has similar beneficial effects in radiation-damaged hemopoiesis. Bone marrow damage was precipitated by total body irradiation (TBI) using single increasing doses (2-10 Gy) of γ—irradiation in groups of mice. Lethality was well correlated with damage in hemopoiesis measured by cellularity of bone marrow (LD50 values were 4.8 and 5.3 gray respectively). Rosiglitazone, an insulin-sensitizing drug, had no significant effect on bone marrow cellularity. Insulin resistance associated with obesity or diabetes mellitus type 2 is intensively growing among cancer patients requiring some kind of radiotherapy. Therefore it is important to know whether drugs used for their therapy can modify radiation effects.

  5. Neutron dosimetry and radiation damage calculations for HFBR

    SciTech Connect

    Greenwood, L.R.; Ratner, R.T.

    1998-03-01

    Neutron dosimetry measurements have been conducted for various positions of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) in order to measure the neutron flux and energy spectra. Neutron dosimetry results and radiation damage calculations are presented for positions V10, V14, and V15.

  6. Radiation damage effects in candidate titanates for Pu disposition: Pyrochlore

    NASA Astrophysics Data System (ADS)

    Strachan, D. M.; Scheele, R. D.; Buck, E. C.; Icenhower, J. P.; Kozelisky, A. E.; Sell, R. L.; Elovich, R. J.; Buchmiller, W. C.

    2005-10-01

    Laboratory experiments on titanate ceramics were performed to verify whether certain assumptions are valid regarding the swelling, chemical durability, and microcracking that might occur as 239Pu decays. Titanate ceramics are the material of choice for the immobilization of surplus weapons-grade Pu. The short-lived isotope 238Pu, was incorporated into the ceramic formulation to accelerate the effects of radiation-induced damage. We report on the effects of this damage on the density (volumetric swelling <6%), crystal structure of pyrochlore-bearing specimens (amorphous after about 2 × 1018 α/g), and dissolution (no change from the fully crystalline specimen). Even though the specimens became amorphous during the tests, there was no evidence for microcracking in the photomicrographs from the scanning electron microscope. Thus, although pyrochlore is susceptible to radiation-induced damage, the material remains chemically and physically viable as a material for immobilizing surplus weapons-grade Pu.

  7. Analyses of the Secondary Particle Radiation and the DNA Damage it Causes to Human Keratinocytes

    SciTech Connect

    Lebel E. A.; Tafrov S.; Rusek, A.; Sivertz, M. B.; Yip, K.; Thompson, K. H.

    2011-11-01

    High-energy protons, and high mass and energy ions, along with the secondary particles they produce, are the main contributors to the radiation hazard during space explorations. Skin, particularly the epidermis, consisting mainly of keratinocytes with potential for proliferation and malignant transformation, absorbs the majority of the radiation dose. Therefore, we used normal human keratinocytes to investigate and quantify the DNA damage caused by secondary radiation. Its manifestation depends on the presence of retinol in the serum-free media, and is regulated by phosphatidylinositol 3-kinases. We simulated the generation of secondary radiation after the impact of protons and iron ions on an aluminum shield. We also measured the intensity and the type of the resulting secondary particles at two sample locations; our findings agreed well with our predictions. We showed that secondary particles inflict DNA damage to different extents, depending on the type of primary radiation. Low-energy protons produce fewer secondary particles and cause less DNA damage than do high-energy protons. However, both generate fewer secondary particles and inflict less DNA damage than do high mass and energy ions. The majority of cells repaired the initial damage, as denoted by the presence of 53BPI foci, within the first 24 hours after exposure, but some cells maintained the 53BP1 foci longer.

  8. Analyses of the secondary particle radiation and the DNA damage it causes to human keratinocytes

    SciTech Connect

    Lebel E.; Rusek A.; Sivertz, M.; Yip, K.; Thompson, K.; Tafrov, S.

    2011-11-22

    High-energy protons, and high mass and energy ions, along with the secondary particles they produce, are the main contributors to the radiation hazard during space explorations. Skin, particularly the epidermis, consisting mainly of keratinocytes with potential for proliferation and malignant transformation, absorbs the majority of the radiation dose. Therefore, we used normal human keratinocytes to investigate and quantify the DNA damage caused by secondary radiation. Its manifestation depends on the presence of retinol in the serum-free media, and is regulated by phosphatidylinositol 3-kinases. We simulated the generation of secondary radiation after the impact of protons and iron ions on an aluminum shield. We also measured the intensity and the type of the resulting secondary particles at two sample locations; our findings agreed well with our predictions. We showed that secondary particles inflict DNA damage to different extents, depending on the type of primary radiation. Low-energy protons produce fewer secondary particles and cause less DNA damage than do high-energy protons. However, both generate fewer secondary particles and inflict less DNA damage than do high mass and energy ions. The majority of cells repaired the initial damage, as denoted by the presence of 53BPI foci, within the first 24 hours after exposure, but some cells maintained the 53BP1 foci longer.

  9. Proton-induced radiation damage in germanium detectors

    SciTech Connect

    Bruckner, J.; Korfer, M.; Wanke, H. , Mainz ); Schroeder, A.N.F. ); Figes, D.; Dragovitsch, P. ); Englert, P.A.J. ); Starr, R.; Trombka, J.I. . Goddard Space Flight Center); Taylor, I. ); Drake, D.M.; Shunk, E.R. )

    1991-04-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10{sub 8} protons cm{sup {minus}2} (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific as well as engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage the detectors were stepwise annealed at temperatures T {le} 110{degrees}C while staying specially designed cryostats. This paper shows that n-type HPGe detectors can be used in charged particles environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

  10. Proton-induced radiation damage in germanium detectors

    NASA Technical Reports Server (NTRS)

    Brueckner, J.; Koerfer, M.; Waenke, H.; Schroeder, A. N. F.; Filges, D.; Dragovitsch, P.; Englert, P. A. J.; Starr, R.; Trombka, J. I.

    1991-01-01

    High-purity germanium (HPGe) detectors will be used in future space missions for gamma-ray measurements and will be subject to interactions with energetic particles. To simulate this process, several large-volume n-type HPGe detectors were incrementally exposed to a particle fluence of up to 10 to the 8th protons/sq cm (proton energy: 1.5 GeV) at different operating temperatures (90 to 120 K) to induce radiation damage. Basic scientific and engineering data on detector performance were collected. During the incremental irradiation, the peak shape produced by the detectors showed a significant change from a Gaussian shape to a broad complex structure. After the irradiation, all detectors were thoroughly characterized by measuring many parameters. To remove the accumulated radiation damage, the detectors were stepwise-annealed at temperatures below 110 C, while kept in their specially designed cryostats. This study shows that n-type HPGe detectors can be used in charged-particle environments as high-energy resolution devices until a certain level of radiation damage is accumulated and that the damage can be removed at moderate annealing temperatures and the detector returned to operating condition.

  11. GUI to Facilitate Research on Biological Damage from Radiation

    NASA Technical Reports Server (NTRS)

    Cucinotta, Frances A.; Ponomarev, Artem Lvovich

    2010-01-01

    A graphical-user-interface (GUI) computer program has been developed to facilitate research on the damage caused by highly energetic particles and photons impinging on living organisms. The program brings together, into one computational workspace, computer codes that have been developed over the years, plus codes that will be developed during the foreseeable future, to address diverse aspects of radiation damage. These include codes that implement radiation-track models, codes for biophysical models of breakage of deoxyribonucleic acid (DNA) by radiation, pattern-recognition programs for extracting quantitative information from biological assays, and image-processing programs that aid visualization of DNA breaks. The radiation-track models are based on transport models of interactions of radiation with matter and solution of the Boltzmann transport equation by use of both theoretical and numerical models. The biophysical models of breakage of DNA by radiation include biopolymer coarse-grained and atomistic models of DNA, stochastic- process models of deposition of energy, and Markov-based probabilistic models of placement of double-strand breaks in DNA. The program is designed for use in the NT, 95, 98, 2000, ME, and XP variants of the Windows operating system.

  12. Research on quick seismic damage investigation using smartphone

    NASA Astrophysics Data System (ADS)

    Zhao, Xuefeng; Han, Ruicong; Yu, Yan; Li, Mingchu

    2016-04-01

    Quick seismic damage investigation in earthquake zone is significant to provide guidance for emergency response and rescue after disaster. In this paper, the damage investigation software is developed, which integrates the functions of questionnaire and picture collection for phenomenon register and image acquisition. The software has been updated to online version, all the information collected can be uploaded to the website with their GPS information, and demonstrated on a map. The expert can evaluate the seismic damage by analyzing the photos and recordings collected, which reduce the waste of human and time.

  13. Modification of radiation-induced oxidative damage in liposomal and microsomal membrane by eugenol

    NASA Astrophysics Data System (ADS)

    Pandey, B. N.; Lathika, K. M.; Mishra, K. P.

    2006-03-01

    Radiation-induced membrane oxidative damage, and their modification by eugenol, a natural antioxidant, was investigated in liposomes and microsomes. Liposomes prepared with DPH showed decrease in fluorescence after γ-irradiation, which was prevented significantly by eugenol and correlated with magnitude of oxidation of phospholipids. Presence of eugenol resulted in substantial inhibition in MDA formation in irradiated liposomes/microsomes, which was less effective when added after irradiation. Similarly, the increase in phospholipase C activity observed after irradiation in microsomes was inhibited in samples pre-treated with eugenol. Results suggest association of radio- oxidative membrane damage with alterations in signaling molecules, and eugenol significantly prevented these membrane damaging events.

  14. Feasibility of OCT to detect radiation-induced esophageal damage in small animal models (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jelvehgaran, Pouya; Alderliesten, Tanja; Salguero, Javier; Borst, Gerben; Song, Ji-Ying; van Leeuwen, Ton G.; de Boer, Johannes F.; de Bruin, Daniel M.; van Herk, Marcel B.

    2016-03-01

    Lung cancer survival is poor and radiotherapy patients often suffer serious treatment side effects. The esophagus is particularly sensitive leading to reduced food intake or even fistula formation. Only few direct techniques exist to measure radiation-induced esophageal damage, for which knowledge is needed to improve the balance between risk of tumor recurrence and complications. Optical coherence tomography (OCT) is a minimally-invasive imaging technique that obtains cross-sectional, high-resolution (1-10µm) images and is capable of scanning the esophageal wall up to 2-3mm depth. In this study we investigated the feasibility of OCT to detect esophageal radiation damage in mice. In total 30 mice were included in 4 study groups (1 main and 3 control groups). Mice underwent cone-beam CT imaging for initial setup assessment and dose planning followed by single-fraction dose delivery of 4, 10, 16, and 20Gy on 5mm spots, spaced 10mm apart. Mice were repeatedly imaged using OCT: pre-irradiation and up to 3 months post-irradiation. The control groups received either OCT only, irradiation only, or were sham-operated. We used histopathology as gold standard for radiation-induced damage diagnosis. The study showed edema in both the main and OCT-only groups. Furthermore, radiation-induced damage was primarily found in the highest dose region (distal esophagus). Based on the histopathology reports we were able to identify the radiation-induced damage in the OCT images as a change in tissue scattering related to the type of induced damage. This finding indicates the feasibility and thereby the potentially promising role of OCT in radiation-induced esophageal damage assessment.

  15. DNA damage induced by the direct effect of radiation

    NASA Astrophysics Data System (ADS)

    Yokoya, A.; Shikazono, N.; Fujii, K.; Urushibara, A.; Akamatsu, K.; Watanabe, R.

    2008-10-01

    We have studied the nature of DNA damage induced by the direct effect of radiation. The yields of single- (SSB) and double-strand breaks (DSB), base lesions and clustered damage were measured using the agarose gel electrophoresis method after exposing to various kinds of radiations to a simple model DNA molecule, fully hydrated closed-circular plasmid DNA (pUC18). The yield of SSB does not show significant dependence on linear energy transfer (LET) values. On the other hand, the yields of base lesions revealed by enzymatic probes, endonuclease III (Nth) and formamidopyrimidine DNA glycosylase (Fpg), which excise base lesions and leave a nick at the damage site, strongly depend on LET values. Soft X-ray photon (150 kVp) irradiation gives a maximum yield of the base lesions detected by the enzymatic probes as SSB and clustered damage, which is composed of one base lesion and proximate other base lesions or SSBs. The clustered damage is visualized as an enzymatically induced DSB. The yields of the enzymatically additional damages strikingly decrease with increasing levels of LET. These results suggest that in higher LET regions, the repair enzymes used as probes are compromised because of the dense damage clustering. The studies using simple plasmid DNA as a irradiation sample, however, have a technical difficulty to detect multiple SSBs in a plasmid DNA. To detect the additional SSBs induced in opposite strand of the first SSB, we have also developed a novel technique of DNA-denaturation assay. This allows us to detect multiply induced SSBs in both strand of DNA, but not induced DSB.

  16. Mitochondria regulate DNA damage and genomic instability induced by high LET radiation

    NASA Astrophysics Data System (ADS)

    Zhang, Bo; Davidson, Mercy M.; Hei, Tom K.

    2014-04-01

    High linear energy transfer (LET) radiation including α particles and heavy ions is the major type of radiation found in space and is considered a potential health risk for astronauts. Even though the chance that these high LET particles traversing through the cytoplasm of cells is higher than that through the nuclei, the contribution of targeted cytoplasmic irradiation to the induction of genomic instability and other chromosomal damages induced by high LET radiation is not known. In the present study, we investigated whether mitochondria are the potential cytoplasmic target of high LET radiation in mediating cellular damage using a mitochondrial DNA (mtDNA) depleted (ρ0) human small airway epithelial (SAE) cell model and a precision charged particle microbeam with a beam width of merely one micron. Targeted cytoplasmic irradiation by high LET α particles induced DNA oxidative damage and double strand breaks in wild type ρ+ SAE cells. Furthermore, there was a significant increase in autophagy and micronuclei, which is an indication of genomic instability, together with the activation of nuclear factor kappa-B (NF-κB) and mitochondrial inducible nitric oxide synthase (iNOS) signaling pathways in ρ+ SAE cells. In contrast, ρ0 SAE cells exhibited a significantly lower response to these same endpoints examined after cytoplasmic irradiation with high LET α particles. The results indicate that mitochondria are essential in mediating cytoplasmic radiation induced genotoxic damage in mammalian cells. Furthermore, the findings may shed some light in the design of countermeasures for space radiation.

  17. Mitochondria regulate DNA damage and genomic instability induced by high LET radiation

    PubMed Central

    Zhang, Bo; Davidson, Mercy M.; Hei, Tom K.

    2014-01-01

    High linear energy transfer (LET) radiation including α particles and heavy ions is the major type of radiation find in space and is considered a potential health risk for astronauts. Even though the chance that these high LET particles traversing through the cytoplasm of cells is higher than that through the nuclei, the contribution of targeted cytoplasmic irradiation, to the induction of genomic instability and other chromosomal damages induced by high LET radiation is not known. In the present study, we investigated whether mitochondria are the potential cytoplasmic target of high LET radiation in mediating cellular damage using a mitochondrial DNA (mtDNA) depleted (ρ0) human small airway epithelial (SAE) cell model and a precision charged particle microbeam with a beam width of merely one micron. Targeted cytoplasmic irradiation by high LET α particles induced DNA oxidative damage and double strand breaks in wild type ρ+ SAE cells. Furthermore, there was a significant increase in autophagy, micronuclei, which is an indication of genomic instability, together with the activation of nuclear factor kappa-B (NF-κB) and mitochondrial inducible nitric oxide synthase (iNOS) signaling pathways in ρ+ SAE cells. In contrast, ρ0 SAE cells exhibited a significantly lower response to these same endpoints examined after cytoplasmic irradiation with high LET α particles. The results indicate that mitochondria are essential in mediating cytoplasmic radiation induced genotoxic damage in mammalian cells. Furthermore, the findings may shed some light in the design of countermeasures for space radiation. PMID:25072018

  18. Induced swelling in radiation damaged ZrSiO 4

    NASA Astrophysics Data System (ADS)

    Exarhos, G. J.

    1984-02-01

    A hydrothermal gelation method was used to prepare phase pure polycrystalline ZrSiO 4 which was sintered to 95% theoretical density. Actinide doped samples containing 10 wt% 238Pu were prepared by an analogous procedure and incurred bulk radiation damage through internal alpha-decay processes. Undoped samples were subjected to external irradiation from 5.5 MeV alpha sources, and from a 60Co gamma source. Actinide doped ZrSiO 4 exhibits dose dependent swelling caused by displacement processes leading to ingrowth of amorphous regions. Bulk density and XRD measurements, as a function of dose, showed first order exponential ingrowth behavior similar to that observed in other actinide doped materials. Results are compared with reported data for naturally damaged crystals subjected to significantly lower alpha decay rates. No significant dose rate dependence on damage ingrowth has been observed. Kinetic models for the observed dose dependent swelling are proposed and rate constants for damage ingrowth in synthetic and natural crystals are compared. To study localized damage induced by both external alpha and gamma irradiation, vibrational Raman measurements were obtained for several accumulated doses. Results indicate that the initial stage of damage ingrowth is confined to the silicate sublattice. Vibrational results will be discussed in terms of microstructural changes which result from irradiation.

  19. Damage-tolerant nanotwinned metals with nanovoids under radiation environments

    SciTech Connect

    Chen, Y.; Yu, K. Y.; Liu, Y.; Shao, S.; Wang, H.; Kirk, M. A.; Wang, J.; Zhang, X.

    2015-04-24

    Material performance in extreme radiation environments is central to the design of future nuclear reactors. Radiation induces significant damage in the form of dislocation loops and voids in irradiated materials, and continuous radiation often leads to void growth and subsequent void swelling in metals with low stacking fault energy. Here we show that by using in situ heavy ion irradiation in a transmission electron microscope, pre-introduced nanovoids in nanotwinned Cu efficiently absorb radiation-induced defects accompanied by gradual elimination of nanovoids, enhancing radiation tolerance of Cu. In situ studies and atomistic simulations reveal that such remarkable self-healing capability stems from high density of coherent and incoherent twin boundaries that rapidly capture and transport point defects and dislocation loops to nanovoids, which act as storage bins for interstitial loops. This study describes a counterintuitive yet significant concept: deliberate introduction of nanovoids in conjunction with nanotwins enables unprecedented damage tolerance in metallic materials.

  20. Radiation damage studies of detector-compatible Si JFETs

    NASA Astrophysics Data System (ADS)

    Dalla Betta, Gian-Franco; Boscardin, Maurizio; Candelori, Andrea; Pancheri, Lucio; Piemonte, Claudio; Ratti, Lodovico; Zorzi, Nicola

    2007-03-01

    We have largely improved the performance of our detector-compatible Si JFETs by optimizing the fabrication technology. New devices feature thermal noise values close to the theoretical ones, and remarkably low 1/ f noise figures. In view of adopting these JFETs for X-ray imaging and HEP applications, bulk and surface radiation damage tests have been carried out by irradiating single transistors and test structures with neutrons and X-rays. Selected results from static and noise characterization of irradiated devices are discussed in this paper, and the impact of radiation effects on the performance of JFET-based circuits is addressed.

  1. Proton induced radiation damage in fast crystal scintillators

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Zhang, Liyuan; Zhu, Ren-Yuan; Kapustinsky, Jon; Nelson, Ron; Wang, Zhehui

    2016-07-01

    This paper reports proton induced radiation damage in fast crystal scintillators. A 20 cm long LYSO crystal, a 15 cm long CeF3 crystal and four liquid scintillator based sealed quartz capillaries were irradiated by 800 MeV protons at Los Alamos up to 3.3 ×1014 p /cm2. Four 1.5 mm thick LYSO plates were irradiated by 24 GeV protons at CERN up to 6.9 ×1015 p /cm2. The results show an excellent radiation hardness of LYSO crystals against charged hadrons.

  2. Extreme radiation damage in soil from Mare Fecunditatis.

    NASA Technical Reports Server (NTRS)

    Phakey, P. P.; Price, P. B.

    1972-01-01

    High-voltage electron microscopy has been used to compare radiation effects in micron-size soil grains from the Luna 16 site (Mare Fecunditatis) and the four Apollo landing sites. Radiation damage by heavy solar particles is strikingly greater in the Luna 16 sample than in the other four samples. It is suggested that less movement of the soil at Mare Fecunditatis has taken place, perhaps because of its proximity to the limb and consequent lower exposure to energetic electrons in the earth's magnetospheric tail, which would cause electrostatic agitation of fine particles.

  3. A stochastic model of radiation-induced bone marrow damage

    SciTech Connect

    Cotlet, G.; Blue, T.E.

    2000-03-01

    A stochastic model, based on consensus principles from radiation biology, is used to estimate bone-marrow stem cell pool survival (CFU-S and stroma cells) after irradiation. The dose response model consists of three coupled first order linear differential equations which quantitatively describe time dependent cellular damage, repair, and killing of red bone marrow cells. This system of differential equations is solved analytically through the use of a matrix approach for continuous and fractionated irradiations. The analytic solutions are confirmed through the dynamical solution of the model equations using SIMULINK. Rate coefficients describing the cellular processes of radiation damage and repair, extrapolated to humans from animal data sets and adjusted for neutron-gamma mixed fields, are employed in a SIMULINK analysis of criticality accidents. The results show that, for the time structures which may occur in criticality accidents, cell survival is established mainly by the average dose and dose rate.

  4. Radiation damage in zircon by high-energy electron beams

    SciTech Connect

    Jiang Nan; Spence, John C. H.

    2009-06-15

    Radiation damage induced by high-energy (200 keV) electron irradiation in zircon has been studied thoroughly using imaging, diffraction, and electron energy-loss spectroscopy techniques in transmission electron microscopy. Both structural and compositional changes during the damage were measured using the above techniques in real time. It was found that the damage was mainly caused by the preferential sputtering of O. The loss of O occurred initially within small sporadic regions with dimension of several nanometers, resulting in the direct transformation of zircon into Zr{sub x}Si{sub y}. These isolated patches gradually connect each other and eventually cover the whole area of the electron beam. These differ from the previous observations either in the self-irradiated natural and synthetic zircon or in ion-beam irradiated thin zircon specimen.

  5. Pluripotent Stem Cells and DNA Damage Response to Ionizing Radiations.

    PubMed

    Mujoo, Kalpana; Butler, E Brian; Pandita, Raj K; Hunt, Clayton R; Pandita, Tej K

    2016-07-01

    Pluripotent stem cells (PSCs) hold great promise in regenerative medicine, disease modeling, functional genomics, toxicological studies and cell-based therapeutics due to their unique characteristics of self-renewal and pluripotency. Novel methods for generation of pluripotent stem cells and their differentiation to the specialized cell types such as neuronal cells, myocardial cells, hepatocytes and beta cells of the pancreas and many other cells of the body are constantly being refined. Pluripotent stem cell derived differentiated cells, including neuronal cells or cardiac cells, are ideal for stem cell transplantation as autologous or allogeneic cells from healthy donors due to their minimal risk of rejection. Radiation-induced DNA damage, ultraviolet light, genotoxic stress and other intrinsic and extrinsic factors triggers a series of biochemical reactions known as DNA damage response. To maintain genomic stability and avoid transmission of mutations into progenitors cells, stem cells have robust DNA damage response signaling, a contrast to somatic cells. Stem cell transplantation may protect against radiation-induced late effects. In particular, this review focuses on differential DNA damage response between stem cells and derived differentiated cells and the possible pathways that determine such differences. PMID:27332952

  6. Pluripotent stem cells and DNA damage response to ionizing radiations

    PubMed Central

    Mujoo, Kalpana; Butler, E. Brian; Pandita, Raj K.; Hunt, Clayton R.; Pandita, Tej K.

    2016-01-01

    Pluripotent stem cells (PSCs) hold great promise in regenerative medicine, disease modeling, functional genomics, toxicological studies and cell-based therapeutics due to their unique characteristics of self-renewal and pluripotency. Novel methods for generation of pluripotent stem cells and their differentiation to the specialized cell types such as neuronal cells, myocardial cells, hepatocytes, and beta cells of the pancreas and many other cells of the body are constantly being refined. Pluripotent stem cell derived differentiated cells, including neuronal cells or cardiac cells are ideal for stem cell transplantation as autologous or allogeneic cells from healthy donors due to their minimum risks of rejection. DNA damage induced by ionizing radiation (IR), ultraviolet (UV) light, genotoxic stress, and other intrinsic and extrinsic factors trigger a series of biochemical reactions termed as DNA damage response (DDR). In order to maintain genomic stability, and avoid transmission of mutations into progenitors cells, stem cells have robust DNA damage response signaling – a contrast to somatic cells. Stem cell transplantation may over come the late effects related to radiation. This review will particularly focus on differential DNA damage response between stem cells and derived differentiated cells and the possible pathways that determine such differences. PMID:27332952

  7. Multiscale approach to the physics of radiation damage with ions

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2014-11-01

    The multiscale approach to the assessment of biodamage resulting upon irradiation of biological media with ions is reviewed, explained and compared to other approaches. The processes of ion propagation in the medium concurrent with ionization and excitation of molecules, transport of secondary products, dynamics of the medium, and biological damage take place on a number of different temporal, spatial and energy scales. The multiscale approach, a physical phenomenon-based analysis of the scenario that leads to radiation damage, has been designed to consider all relevant effects on a variety of scales and develop an approach to the quantitative assessment of biological damage as a result of irradiation with ions. Presently, physical and chemical effects are included in the scenario while the biological effects such as DNA repair are only mentioned. This paper explains the scenario of radiation damage with ions, overviews its major parts, and applies the multiscale approach to different experimental conditions. On the basis of this experience, the recipe for application of the multiscale approach is formulated. The recipe leads to the calculation of relative biological effectiveness.

  8. Radiation damage effects in candidate titanates for Pu disposition: Zirconolite

    NASA Astrophysics Data System (ADS)

    Strachan, D. M.; Scheele, R. D.; Buck, E. C.; Kozelisky, A. E.; Sell, R. L.; Elovich, R. J.; Buchmiller, W. C.

    2008-01-01

    Results from studies of radiation-induced damage from the alpha decay of 238Pu on the density and crystal structure of a nominally phase-pure zirconolite and two other zirconolite-bearing ceramics are discussed. Macro and micro swelling were found to be temperature independent, whereas the density determined with He gas pycnometry was temperature dependent. Approximately 2.6 × 10 18 α/g were needed to render the specimens X-ray amorphous- more to saturate the swelling. Unlike pyrochlore-based ceramics, we did not observe any phase changes associated with storage temperature and damage ingrowth. The forward dissolution rate at a pH value of 2 for material containing essentially all zirconolite is 1.7(4) × 10 -3 g/(m 2 d) with very little pH dependence and no dependence on the amount of radiation-induced damage. Even after the radiation-induced swelling saturated, the specimens remained physically intact with no evidence for microcracking. Thus, the material remains physically a viable material for the disposition of surplus weapons-grade Pu.

  9. Ascorbic acid (AA) metabolism in protection against radiation damage

    SciTech Connect

    Rose, R.C.; Koch, M.J.

    1986-03-05

    The possibility is considered that AA protects tissues against radiation damage by scavenging free radicals that result from radiolysis of water. A physiologic buffer (pH 6.7) was incubated with /sup 14/C-AA and 1 mM thiourea (to slow spontaneous oxidation of AA). Aliquots were assayed by HPLC and scintillation spectrometry to identify the /sup 14/C-label. Samples exposed to Cobalt-60 radiation had a half time of AA decay of < 3 minutes compared with nonirradiated samples (t/sub 1/2/ > 30 minutes) indicating that AA scavenges radiation-induced free radicals and forms the ascorbate free radical (AFR). Pairs of /sup 14/C-AFR disproportionate, with the net effect of /sup 14/C-dehydroascorbic acid formation from /sup 14/C-AA. Having established that AFR result from ionizing radiation in an aqueous solution, the possibility was evaluated that a tissue factor reduces AFR. Cortical tissue from the kidneys of male rats was minced, homogenized in buffer and centrifuged at 8000 xg. The supernatant was found to slow the rate of radiation-induced AA degradation by > 90% when incubated at 23/sup 0/C in the presence of 15 ..mu..M /sup 14/C-AA. Samples of supernatant maintained at 100/sup 0/C for 10 minutes or precipitated with 5% PCA did not prevent radiation-induced AA degradation. AA may have a specific role in scavenging free radicals generated by ionizing radiation and thereby protect body tissues.

  10. Modification of high LET radiation-induced damage and its repair in yeast by hypoxia.

    PubMed

    Subrahmanyam, P; Rao, B S; Reddy, N M; Murthy, M S; Madhvanath, U

    1979-11-01

    The lethal response of a diploid yeast strain BZ34 to densely ionizing radiations from the reaction 10B(n, alpha)7 Li was studied. The values for relative biological effectiveness (r.b.e.) and oxygen enhancement ratio (o.e.r.) for this radiation compare favourably with the data obtained with charged particles on the same strain of yeast. Recovery from potentially lethal damage was also studied by post-irradiation holding under non-nutrient conditions. In order to understand the role of oxygen in the recovery process, the investigation covered the following treatment regimens: (a) aerobic irradiation and aerobic holding (A-A), (b) aerobic irradiation and hypoxic holding (A-H), (c) hypoxic irradiation and hypoxic holding (H-H) and (d) hypoxic irradiation and aerobic holding (H-A). It has been found that the presence of oxygen is essential for recovery from the damage induced by both gamma rays and high linear energy transfer (LET) radiations. The extent of recovery was larger for gamma-induced damage than for damage induced by high LET radiation (alpha + 7Li) for the A-A condition. In the H-H condition, while only a slight recovery was seen for gamma-induced damage, it was totally absent for high LET damage. For the modality A-H, it was found that there is not recovery from the sparsely ionising gamma radiation-induced damage. The implications of these results for the treatment of malignant tumours by radiotherapy are briefly discussed. PMID:397200

  11. Molecular responses of radiation-induced liver damage in rats

    PubMed Central

    CHENG, WEI; XIAO, LEI; AINIWAER, AIMUDULA; WANG, YUNLIAN; WU, GE; MAO, RUI; YANG, YING; BAO, YONGXING

    2015-01-01

    The aim of the present study was to investigate the molecular responses involved in radiation-induced liver damage (RILD). Sprague-Dawley rats (6-weeks-old) were irradiated once at a dose of 20 Gy to the right upper quadrant of the abdomen. The rats were then sacrificed 3 days and 1, 2, 4, 8 and 12 weeks after irradiation and rats, which were not exposed to irradiation were used as controls. Weight measurements and blood was obtained from the rats and liver tissues were collected for histological and apoptotic analysis. Immunohistochemistry, reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were performed to measure the expression levels of mRNAs and proteins, respectively. The serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase were increased significantly in the RILD rats. Histological investigation revealed the proliferation of collagen and the formation of fibrotic tissue 12 weeks after irradiation. Apoptotic cells were observed predominantly 2 and 4 weeks after irradiation. The immunohistochemistry, RT-qPCR and western blot analysis all revealed the same pattern of changes in the expression levels of the molecules assessed. The expression levels of transforming growth factor-β1 (TGF-β1), nuclear factor (NF)-κB65, mothers against decapentaplegic homolog 3 (Smad3) and Smad7 and connective tissue growth factor were increased during the recovery period following irradiation up to 12 weeks. The expression levels of tumor necrosis factor-α, Smad7 and Smad4 were only increased during the early phase (first 4 weeks) of recovery following irradiation. In the RILD rat model, the molecular responses indicated that the TGF-β1/Smads and NF-κB65 signaling pathways are involved in the mechanism of RILD recovery. PMID:25483171

  12. Investigating Undergraduate Students’ Conceptions of Radiation

    NASA Astrophysics Data System (ADS)

    Romine, James M.; Buxner, Sanlyn; Impey, Chris; Nieberding, Megan; Antonellis, Jessie C.

    2014-11-01

    Radiation is an essential topic to the physical sciences yet is often misunderstood by the general public. The last time most people have formal instruction about radiation is as students in high school and this knowledge will be carried into adulthood. Peoples’ conceptions of radiation influence their attitude towards research regarding radiation, radioactivity, and other work where radiation is prevalent. In order to understand students’ ideas about radiation after having left high school, we collected science surveys from nearly 12,000 undergraduates enrolled in introductory science courses over a span of 25 years. This research investigates the relationship between students’ conceptions of radiation and students’ personal beliefs and academic field of study.Our results show that many students in the sample were unable to adequately describe radiation. Responses were typically vague, brief, and emotionally driven. Students’ field of study was found to significantly correlate with their conceptions. Students pursuing STEM majors were 60% more likely to describe radiation as an emission and/or form of energy and cited atomic or radioactive sources of radiation twice as often as non-STEM students. Additionally, students’ personal beliefs also appear to relate to their conceptions of radiation. The most prominent misconception shown was that radiation is a generically harmful substance, which was found to be consistent throughout the duration of the study. In particular, non-science majors in our sample had higher rates of misconceptions, often generalized the idea of radiation into a broad singular topic, and had difficulty properly identifying sources.Generalized ideas of radiation and the inability to properly recognize sources of radiation may contribute to the prevalent misconception that radiation is an inexplicably dangerous substance. A basic understanding of both electromagnetic and particulate radiation and the existence of radiation at various

  13. Contribution of endogenous and exogenous damage to the total radiation-induced damage in the bacterial spore

    SciTech Connect

    Jacobs, G.P.; Samuni, A.; Czapski, G.

    1980-01-01

    Radical scavengers such as polyethylene glycol 4000 and bovine albumin have been used to define the contribution of exogenous and endogenous damage to the total radiation-induced damage in aqueous buffered suspensions of Bacillus pumilus spores. The results indicate that this damage in the bacterial spore is predominantly endogenous.

  14. PREFACE: Radiation Damage in Biomolecular Systems (RADAM07)

    NASA Astrophysics Data System (ADS)

    McGuigan, Kevin G.

    2008-03-01

    The annual meeting of the COST P9 Action `Radiation damage in biomolecular systems' took place from 19-22 June 2007 in the Royal College of Surgeons in Ireland, in Dublin. The conference was structured into 5 Working Group sessions: Electrons and biomolecular interactions Ions and biomolecular interactions Radiation in physiological environments Theoretical developments for radiation damage Track structure in cells Each of the five working groups presented two sessions of invited talks. Professor Ron Chesser of Texas Tech University, USA gave a riveting plenary talk on `Mechanisms of Adaptive Radiation Responses in Mammals at Chernobyl' and the implications his work has on the Linear-No Threshold model of radiation damage. In addition, this was the first RADAM meeting to take place after the Alexander Litvenenko affair and we were fortunate to have one of the leading scientists involved in the European response Professor Herwig Paretzke of GSF-Institut für Strahlenschutz, Neuherberg, Germany, available to speak. The remaining contributions were presented in the poster session. A total of 72 scientific contributions (32 oral, 40 poster), presented by 97 participants from 22 different countries, gave an overview on the current progress in the 5 different subfields. A 1-day pre-conference `Early Researcher Tutorial Workshop' on the same topic kicked off on 19 June attended by more than 40 postgrads, postdocs and senior researchers. Twenty papers, based on these reports, are included in this volume of Journal of Physics: Conference Series. All the contributions in this volume were fully refereed, and they represent a sample of the courses, invited talks and contributed talks presented during RADAM07. The interdisciplinary RADAM07 conference brought together researchers from a variety of different fields with a common interest in biomolecular radiation damage. This is reflected by the disparate backgrounds of the authors of the papers presented in these proceedings

  15. Molecular dynamics modelling of radiation damage in zircon

    NASA Astrophysics Data System (ADS)

    Grechanovsky, A. E.

    2009-04-01

    Zircon (ZrSiO4) is among actinide-bearing phases which has been proposed as a crystalline confinement matrix for nuclear waste management, especially for weapon-grade plutonium and UO2 spent fuel in the USA. Zircon is also widely used in geochronology. But, with accumulating α-decay damage, zircon undergoes a radiation induced transition to an amorphous (or metamict) state. So, in the present work molecular dynamics simulations (MD simulations) of zircon structure have been performed to study radiation damage in zircon. In this technique, one simulates the propagation of an energetic particle in a system of atoms interacting via model potentials, by integrating the Newton equations of motion. Author has used version 3.09 of the DL_POLY molecular simulation package. Zircon structure containing 181944 atoms (19x19x21 unit cells) was equilibrated at 300 K for 10 ps, and one Zr atom (usually called the primary knock-on atom, PKA) was given a velocity corresponding to an implantation energy of about 20 keV. MD simulations were performed in the microcanonical ensemble that is under conditions of constant particle number, volume and energy. Results of the MD simulations show that the number of interstitials is equal to 840 atoms. This is very close (4000-5000 atoms for 70 keV recoil atom 234Th) to what is measured in the diffuse x-ray scattering and NMR experiments on amorphous metamict samples (damaged by natural irradiation) of geological age. It has been shown that the damaged structure contains several depleted regions with characteristic sized up to 2,5 nm after single event and up to 4,5 nm after three overlapping events. Furthermore, these events produce channels of depleted matter between the overlapping damaged regions. These channels provide a high-diffusivity path for radiogenic Pb (percolation effect). Loss of radiogenic Pb may result in to incorrect dating of rocks.

  16. Investigation of subsidence damages above abandoned mine lands

    SciTech Connect

    Lin, Po-Ming.

    1988-01-01

    Abandoned mine lands (AML) subsidence is one of the most hazardous problems for personal property and community development. In order to improve the technique for subsidence diagnosis and the effectiveness of remedial measures, several methods and techniques have been developed in this research. A subsidence site investigation checklist is developed to guide the investigators with or without hands-on experience to collect a complete and necessary information for subsidence analysis during site investigation. A subsidence cause identification system is developed to streamline the process of analysis and for subsidence cause differentiation and identification over AML. A damage severity system is developed to evaluate the intensity of the damage to structures. A subsidence deduction model is developed based on the probability function integration method to reconstruct subsidence profile and subsurface failure zone for AML subsidence. The study is based on the case studies which include site investigation, surface subsidence survey, subsurface instrumentation, damage severity evaluation, subsidence deduction and statistical analysis. The results show that geologic conditions such as seam depth, seam height, ratios of strong and weak rocks do affect the subsidence damage area, subsidence factor, and damage severity. The relationship between above parameters can be expressed by a second order polynomial with correlation coefficients ranging from 0.7 to 0.9.

  17. Investigation of graphene-based nanoscale radiation sensitive materials

    NASA Astrophysics Data System (ADS)

    Robinson, Joshua A.; Wetherington, Maxwell; Hughes, Zachary; LaBella, Michael, III; Bresnehan, Michael

    2012-06-01

    Current state-of-the-art nanotechnology offers multiple benefits for radiation sensing applications. These include the ability to incorporate nano-sized radiation indicators into widely used materials such as paint, corrosion-resistant coatings, and ceramics to create nano-composite materials that can be widely used in everyday life. Additionally, nanotechnology may lead to the development of ultra-low power, flexible detection systems that can be embedded in clothing or other systems. Graphene, a single layer of graphite, exhibits exceptional electronic and structural properties, and is being investigated for high-frequency devices and sensors. Previous work indicates that graphene-oxide (GO) - a derivative of graphene - exhibits luminescent properties that can be tailored based on chemistry; however, exploration of graphene-oxide's ability to provide a sufficient change in luminescent properties when exposed to gamma or neutron radiation has not been carried out. We investigate the mechanisms of radiation-induced chemical modifications and radiation damage induced shifts in luminescence in graphene-oxide materials to provide a fundamental foundation for further development of radiation sensitive detection architectures. Additionally, we investigate the integration of hexagonal boron nitride (hBN) with graphene-based devices to evaluate radiation induced conductivity in nanoscale devices. Importantly, we demonstrate the sensitivity of graphene transport properties to the presence of alpha particles, and discuss the successful integration of hBN with large area graphene electrodes as a means to provide the foundation for large-area nanoscale radiation sensors.

  18. Human umbilical cord mesenchymal stem cells alleviate nasal mucosa radiation damage in a guinea pig model.

    PubMed

    Duan, Hong-Gang; Ji, Fang; Zheng, Chun-Quan; Wang, Chun-Hua; Li, Jing

    2015-02-01

    Nasal complications after radiotherapy severely affect the quality of life of nasopharyngeal carcinoma patients, and there is a compelling need to find novel therapies for nasal epithelial cell radiation damage. Therefore, we investigated the therapeutic effect of human umbilical cord mesenchymal stem cells (hUC-MSCs) in guinea pig model of nasal mucosa radiation damage and explored its therapeutic mechanism. Cultured hUC-MSCs were injected intravenously immediately after radiation in the nasal mucosa-radiation-damage guinea pig model. Migration of hUC-MSCs into the nasal mucosa and the potential for differentiation into nasal epithelial cells were evaluated by immunofluorescence. The therapeutic effects of hUC-MSCs were evaluated by mucus clearance time (MCT), degree of nasal mucosa edema, and the nasal mucosa cilia form and coverage ratio. Results indicate that the hUC-MSCs migrated to the nasal mucosa lamina propria and did not differentiate into nasal epithelial cells in this model. The MCT and degree of mucosal edema were improved at 1 week and 1 month after radiation, respectively, but no difference was found at 3 months and 6 months after radiation. The nasal mucosa cilia form and coverage ratio was not improved 6 months after radiation. Thus, hUC-MSCs can migrate to the nasal mucosa lamina propria and improve MCT and mucosa edema within a short time period, but these cells are unable to differentiate into nasal epithelial cells and improve nasal epithelial regeneration in the nasal mucosa radiation damage guinea pig model. PMID:25209829

  19. Spectromicroscopy of Polymers: Comparison of Radiation Damage with Electron and Photon Core Excitation Spectroscopy Techniques

    NASA Astrophysics Data System (ADS)

    Ade, H.; Smith, A. P.; Rightor, E. G.; Hitchcock, A. P.; Urquhart, S.; Leapman, R.

    1997-03-01

    Core excitation microspectroscopy has become a powerful tool for the characterization of polymeric materials due to its sensitivity to chemical functionality. However, the excitations utilized in electron energy loss spectroscopy performed in a scanning transmission electron microscope (TEM-EELS) and near edge x-ray absorption fine structure (NEXAFS) spectroscopy can introduce radiation damage and chemically modify the sample. In order to understand the radiation damage associated with TEM-EELS and NEXAFS spectroscopy we have studied the radiation damage of the common polymer poly(ethylene terephthalate) (PET) as exhibited by changes in the acquired C K-edge excitation spectra. By fitting gaussian functions to the spectral intensity changes as a function of dose, we have determined the critical radiation dose of PET for both NEXAFS spectroscopy and TEM-EELS under typical operating conditions. This critical radiation dose for TEM-EELS is found to be 1.7 ± 0.2 x 10^8 grey (1.7 ± 0.2 x 10^4 Mrad) compared to a critical radiation dose for NEXAFS spectroscopy of 1.4 ± 0.7 x 10^9 grey (1.4 ± 0.7 x 10^5 Mrad). By considering the G factors of the two techniques and the critical radiation dose, a rule of thumb was derived that indicates that with typical present operating conditions, NEXAFS spectroscopy can analyze areas 500 times smaller than TEM-EELS given the same amount of radiation damage. Work supported by: NSF Young Investigator Award (DMR-9458060) and Dow Chemical

  20. Radiation damage of the HEAO C-1 germanium detectors

    NASA Technical Reports Server (NTRS)

    Mahoney, W. A.; Ling, J. C.; Jacobson, A. S.

    1981-01-01

    The effects of radiation damage from proton bombardment of the four HEAO C-1 high purity germanium detectors have been measured and compared to predictions. Because of the presence of numerous gamma-ray lines in the detector background spectra and because of the relatively long exposure time of the HEAO 3 satellite to cosmic-ray and trapped protons, it has been possible to measure both the energy and time dependence of radiation damage. After 100 d in orbit, each of the four detectors has been exposed to approximately 3 x 10 to the 7th protons/sq cm, and the average energy resolution at 1460 keV had degraded from 3.2 keV fwhm to 8.6 keV fwhm. The lines were all broadened to the low energy side although the line profile was different for each of the four detectors. The damage-related contribution to the degradation in energy resolution was found to be linear in energy and proton influence.

  1. In Situ Measurement of Radiation Damage in Scintillating Fibers

    NASA Astrophysics Data System (ADS)

    Ziegler, Ar.; Holm, U.; Latuske, N.; Wick, K.; Zoufal, T.

    2002-11-01

    The radiation induced degradation of the optical transmission of the fibers SCSF-38M, SCSF-81M (Kuraray), BCF-60 and BCF-98 (Bicron) with polystyrene core (PS) was studied. During and after irradiation with a 100 kV X-ray source, a 137Cs source and a 60Co source the effects depend on the fiber type: (1) The permanent damage for BCF-98 (clear PS) is smaller than for the scintillators. (2) The BCF-60 is radiation harder than the other two scintillators but very light sensitive. Temperature treatments (up to 68°C) of SCSF-38M, without irradiation showed a transmission loss which clearly rises with the increasing temperature. This accelerated ageing phenomenon does not recover and the fiber is permanently damaged. In an additional experiment it was studied whether the transmission damage can be influenced by short illuminations with visible light during and after irradiation. For SCSF-38M a strong reduction of the permanent induced absorption remaining after the end of the recovery process was observed.

  2. Radiation damage and derivatization in macromolecular crystallography: a structure factor’s perspective

    PubMed Central

    Owen, Robin L.; Sherrell, Darren A.

    2016-01-01

    During, or even after, data collection the presence and effects of radiation damage in macromolecular crystallography may not always be immediately obvious. Despite this, radiation damage is almost always present, with site-specific damage occurring on very short time (dose) scales well before global damage becomes apparent. A result of both site-specific radiation damage and derivatization is a change in the relative intensity of reflections. The size and approximate rate of onset of X-ray-induced transformations is compared with the changes expected from derivatization, and strategies for minimizing radiation damage are discussed. PMID:26960125

  3. Torin2 Suppresses Ionizing Radiation-Induced DNA Damage Repair.

    PubMed

    Udayakumar, Durga; Pandita, Raj K; Horikoshi, Nobuo; Liu, Yan; Liu, Qingsong; Wong, Kwok-Kin; Hunt, Clayton R; Gray, Nathanael S; Minna, John D; Pandita, Tej K; Westover, Kenneth D

    2016-05-01

    Several classes of inhibitors of the mammalian target of rapamycin (mTOR) have been developed based on its central role in sensing growth factor and nutrient levels to regulate cellular metabolism. However, its ATP-binding site closely resembles other phosphatidylinositol 3-kinase-related kinase (PIKK) family members, resulting in reactivity with these targets that may also be therapeutically useful. The ATP-competitive mTOR inhibitor, Torin2, shows biochemical activity against the DNA repair-associated proteins ATM, ATR and DNA-PK, which raises the possibility that Torin2 and related compounds might radiosensitize cancerous tumors. In this study Torin2 was also found to enhance ionizing radiation-induced cell killing in conditions where ATM was dispensable, confirming the requirement for multiple PIKK targets. Moreover, Torin2 did not influence the initial appearance of γ-H2AX foci after irradiation but significantly delayed the disappearance of radiation-induced γ-H2AX foci, indicating a DNA repair defect. Torin2 increased the number of radiation-induced S-phase specific chromosome aberrations and reduced the frequency of radiation-induced CtIP and Rad51 foci formation, suggesting that Torin2 works by blocking homologous recombination (HR)-mediated DNA repair resulting in an S-phase specific DNA repair defect. Accordingly, Torin2 reduced HR-mediated repair of I-Sce1-induced DNA damage and contributed to replication fork stalling. We conclude that radiosensitization of tumor cells by Torin2 is associated with disrupting ATR- and ATM-dependent DNA damage responses. Our findings support the concept of developing combination cancer therapies that incorporate ionizing radiation therapy and Torin2 or compounds with similar properties. PMID:27135971

  4. Recent Advances in Understanding Radiation Damage in Reactor Cavity Concrete

    SciTech Connect

    Rosseel, Thomas M; Field, Kevin G; Le Pape, Yann; Remec, Igor; Giorla, Alain B; Wall, Dr. James Joseph

    2015-01-01

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has resulted in a renewed focus on long-term aging of materials at nuclear power plants (NPPs) including concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis, jointly performed by the Department of Energy, the Nuclear Regulatory Commission and Nuclear Industry, identified the urgent need to develop a consistent knowledge base on irradiation effects in concrete (Graves et al., (2014)). Much of the historical mechanical performance data of irradiated concrete (Hilsdorf et al., (1978)) does not accurately reflect typical radiation conditions in NPPs or conditions out to 60 or 80 years of radiation exposure (Kontani et al., (2011)). To address these potential gaps in the knowledge base, the Electric Power Research Institute and Oak Ridge National Laboratory, are working to better understand radiation damage as a degradation mechanism. This paper outlines recent progress toward: 1) assessing the radiation environment in concrete biological shields and defining the upper bound of the neutron and gamma dose levels expected in the biological shield for extended operation, and estimating adsorbed dose, 2) evaluating opportunities to harvest and test irradiated concrete from international NPPs, 3) evaluating opportunities to irradiate prototypical concrete and its components under accelerated neutron and gamma dose levels to establish conservative bounds and inform damage models, 4) developing improved models to enhance the understanding of the effects of radiation on concrete and 5) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge including developing cooperative test programs to improve confidence in data obtained from various concretes and from accelerated irradiation experiments.

  5. Protective Effects of Polysaccharides from Soybean Meal Against X-ray Radiation Induced Damage in Mouse Spleen Lymphocytes

    PubMed Central

    Yao, Lei; Wang, Zhenyu; Zhao, Haitian; Cheng, Cuilin; Fu, Xiaoyi; Liu, Jiaren; Yang, Xin

    2011-01-01

    The aim of this study was to investigate radioprotective effect of the polysaccharides from soybean meal (SMP) against X-ray radiation-induced damage in mouse spleen lymphocytes. MTT and comet assay were performed to evaluate SMP’s ability to prevent cell death and DNA damage induced by radiation. The results show that, X-ray radiation (30 KV, 10 mA, 8 min (4 Gy)) can significantly increase cell death and DNA fragmentation of mouse spleen lymphocytes. Pretreatment with SMP for 2 h before radiation could increase cell viability, moreover, the SMP can reduce X-ray radiation-induced DNA damage. The percentage of tail DNA and the tail moment of the SMP groups were significantly lower than those of the radiation alone group (p < 0.05). These results suggest SMP may be a good candidate as a radioprotective agent. PMID:22174652

  6. Absolute Measurements of Radiation Damage in Nanometer Thick Films

    PubMed Central

    Alizadeh, Elahe; Sanche, Léon

    2013-01-01

    We address the problem of absolute measurements of radiation damage in films of nanometer thicknesses. Thin films of DNA (~ 2–160nm) are deposited onto glass substrates and irradiated with varying doses of 1.5 keV X-rays under dry N2 at atmospheric pressure and room temperature. For each different thickness, the damage is assessed by measuring the loss of the supercoiled configuration as a function of incident photon fluence. From the exposure curves, the G-values are deduced, assuming that X-ray photons interacting with DNA, deposit all of their energy in the film. The results show that the G-value (i.e., damage per unit of deposited energy) increases with film thickness and reaches a plateau at 30±5 nm. This thickness dependence provides a correction factor to estimate the actual G-value for films with thicknesses below 30nm thickness. Thus, the absolute values of damage can be compared with that of films of any thickness under different experimental conditions. PMID:22562941

  7. The role of nickel in radiation damage of ferritic alloys

    DOE PAGESBeta

    Osetskiy, Yury N.; Anento, Napoleon; Serra, Anna; Terentyev, Dmitry

    2014-11-26

    According to the modern theory damage evolution under neutron irradiation depends on the fraction of self interstitial atoms (SIAs) produced in the form of one-dimensionally (1-D) glissile clusters. These clusters, having a low interaction cross-section with other defects, sink mainly on grain boundaries and dislocations creating the so-called production bias. It is known empirically that addition of certain alloying elements affect many radiation effects, including swelling, however the mechanisms are unknown in many cases. In this paper we report the results of an extensive multi-technique atomistic level modeling of SIA clusters mobility in bcc Fe-Ni alloys with Ni content frommore » 0.8 to 10 at.%. We have found that Ni interacts strongly with periphery of clusters affecting their mobility. The total effect is defined by all Ni atoms interacting with the cluster at the same time and can be significant even in low-Ni alloys. Thus 1nm (37SIAs) cluster is practically immobile at T < 500K in the Fe-0.8at.% Ni alloy. Increasing cluster size and Ni content enhance cluster immobilization. Furthermore, this effect should have quite broad consequences in swelling rate, matrix damage accumulation, radiation induced hardening, etc. and the results obtained help in better understanding and prediction of radiation effects in Fe-Ni ferritic alloys.« less

  8. A radiation damage repair model for normal tissues

    NASA Astrophysics Data System (ADS)

    Partridge, Mike

    2008-07-01

    A cellular Monte Carlo model describing radiation damage and repair in normal epithelial tissues is presented. The deliberately simplified model includes cell cycling, cell motility and radiation damage response (cell cycle arrest and cell death) only. Results demonstrate that the model produces a stable equilibrium system for mean cell cycle times in the range 24-96 h. Simulated irradiation of these stable equilibrium systems produced a range of responses that are shown to be consistent with experimental and clinical observation, including (i) re-epithelialization of radiation-induced lesions by a mixture of cell migration into the wound and repopulation at the periphery; (ii) observed radiosensitivity that is quantitatively consistent with both rate of induction of irreparable DNA lesions and, independently, with the observed acute oral and pharyngeal mucosal reactions to radiotherapy; (iii) an observed time between irradiation and maximum toxicity that is consistent with experimental data for skin; (iv) quantitatively accurate predictions of low-dose hyper-radiosensitivity; (v) Gomperzian repopulation for very small lesions (~2000 cells) and (vi) a linear rate of re-epithelialization of 5-10 µm h-1 for large lesions (>15 000 cells).

  9. The role of nickel in radiation damage of ferritic alloys

    SciTech Connect

    Osetskiy, Yury N.; Anento, Napoleon; Serra, Anna; Terentyev, Dmitry

    2014-11-26

    According to the modern theory damage evolution under neutron irradiation depends on the fraction of self interstitial atoms (SIAs) produced in the form of one-dimensionally (1-D) glissile clusters. These clusters, having a low interaction cross-section with other defects, sink mainly on grain boundaries and dislocations creating the so-called production bias. It is known empirically that addition of certain alloying elements affect many radiation effects, including swelling, however the mechanisms are unknown in many cases. In this paper we report the results of an extensive multi-technique atomistic level modeling of SIA clusters mobility in bcc Fe-Ni alloys with Ni content from 0.8 to 10 at.%. We have found that Ni interacts strongly with periphery of clusters affecting their mobility. The total effect is defined by all Ni atoms interacting with the cluster at the same time and can be significant even in low-Ni alloys. Thus 1nm (37SIAs) cluster is practically immobile at T < 500K in the Fe-0.8at.% Ni alloy. Increasing cluster size and Ni content enhance cluster immobilization. Furthermore, this effect should have quite broad consequences in swelling rate, matrix damage accumulation, radiation induced hardening, etc. and the results obtained help in better understanding and prediction of radiation effects in Fe-Ni ferritic alloys.

  10. Retinal damage from long-term exposure to laser radiation.

    PubMed

    Gibbons, W D; Allen, R G

    1977-06-01

    The maculae of rhesus monkeys were exposed to an argon-ion lazer operated in the TEM00 continuous wave mode at a wavelength of 514.5 nm. Both ophthalmoscopic and histopathologic evaluations of exposure sites were obtained. Threshold (ED50) values were obtained for 0.5, 5, 30, 120, and 1,000 sec. exposure times. Presence of minimum visible lesions was assessed ophthalmoscopically at both 1 hour and 24 hours after exposure. With increasing exposure times, a 24 hr. lesion-appearance criterion resulted in ED50 values too low to be consistent with a thermal damage mechanism. In contrast, exposure to neodymium laser radiation at a 1,060 nm. wavelength for 120 sec. produced only ED50 values consistent with those associated with thermal injury. These results suggest that the damage mechanisms for long-duration exposures to visible light may involve photochemical processes initiated by the interaction of visible light with the retinal photopigments. PMID:405344

  11. A Mathematical Model for Estimating Biological Damage Caused by Radiation

    NASA Astrophysics Data System (ADS)

    Manabe, Yuichiro; Ichikawa, Kento; Bando, Masako

    2012-10-01

    We propose a mathematical model for estimating biological damage caused by low-dose irradiation. We understand that the linear non threshold (LNT) hypothesis is realized only in the case of no recovery effects. In order to treat the realistic living objects, our model takes into account various types of recovery as well as proliferation mechanism, which may change the resultant damage, especially for the case of lower dose rate irradiation. It turns out that the lower the radiation dose rate, the safer the irradiated system of living object (which is called symbolically ``tissue'' hereafter) can have chances to survive, which can reproduce the so-called dose and dose-rate effectiveness factor (DDREF).

  12. Magnetic resonance imaging (MRI): A review of genetic damage investigations.

    PubMed

    Vijayalaxmi; Fatahi, Mahsa; Speck, Oliver

    2015-01-01

    Magnetic resonance imaging (MRI) is a powerful, non-invasive diagnostic medical imaging technique widely used to acquire detailed information about anatomy and function of different organs in the body, in both health and disease. It utilizes electromagnetic fields of three different frequency bands: static magnetic field (SMF), time-varying gradient magnetic fields (GMF) in the kHz range and pulsed radiofrequency fields (RF) in the MHz range. There have been some investigations examining the extent of genetic damage following exposure of bacterial and human cells to all three frequency bands of electromagnetic fields, as used during MRI: the rationale for these studies is the well documented evidence of positive correlation between significantly increased genetic damage and carcinogenesis. Overall, the published data were not sufficiently informative and useful because of the small sample size, inappropriate comparison of experimental groups, etc. Besides, when an increased damage was observed in MRI-exposed cells, the fate of such lesions was not further explored from multiple 'down-stream' events. This review provides: (i) information on the basic principles used in MRI technology, (ii) detailed experimental protocols, results and critical comments on the genetic damage investigations thus far conducted using MRI equipment and, (iii) a discussion on several gaps in knowledge in the current scientific literature on MRI. Comprehensive, international, multi-centered collaborative studies, using a common and widely used MRI exposure protocol (cardiac or brain scan) incorporating several genetic/epigenetic damage end-points as well as epidemiological investigations, in large number of individuals/patients are warranted to reduce and perhaps, eliminate uncertainties raised in genetic damage investigations in cells exposed in vitro and in vivo to MRI. PMID:26041266

  13. Atomic simulations of Fe/Ni multilayer nanocomposites on the radiation damage resistance

    NASA Astrophysics Data System (ADS)

    Chen, Feida; Tang, Xiaobin; Yang, Yahui; Huang, Hai; Liu, Jian; Li, Huan; Chen, Da

    2016-01-01

    We investigated the radiation damage resistance of the Fe/Ni multilayer nanocomposites by molecular dynamics. In the paper, two types of interface configuration with different orientation relationship were constructed. Their morphology evolution and number of final surviving defects induced by cascade collisions were discussed respectively. The interfaces of the two types of Fe/Ni multilayers kept distinct during the long-time relaxation before cascade. The comparison of surviving defects number produced by PKA with 5 keV at 100 K showed that the Fe/Ni multilayers have greater radiation tolerance than that of the bulk materials. However, the orientation relationship of the interface influences the defects self-healing capability greatly when the multilayers are irradiated by higher energy PKA or at high temperature. The radiation damage resistance of the Nishiyama - Wassermann type Fe/Ni multilayers which have larger lattice misfit is more stable than that of the Kurdjumov - Sachs type.

  14. Multiscale physics of ion-induced radiation damage

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2013-06-01

    A multiscale approach to the physics of ion-beam cancer therapy, an approach suggested in order to understand the interplay of a large number of phenomena involved in radiation damage scenario occurring on a range of temporal, spatial, and energy scales, is being reviewed. The scenario is described along with a variety of effects that take place on different temporal, spatial, and energy scales and play major roles in the scenario of interaction of ions with tissue. The understanding of these effects leads to a quantitative assessment of relative biological effectiveness that relates the physical quantities, such as dose, to the biological values, such as the probability of cell survival.

  15. Protection of radiation detectors from fast neutron damage

    SciTech Connect

    Kronenberg, S.

    1984-01-30

    A circuit for biasing a solid state crystal used as a radiation detector in which the passage of the initial gamma ray pulse from the explosion of a nearby tactical nuclear weapon is utilized to temporarily remove the bias from said crystal for a time sufficient to permit the fast neutron pulse from the same explosion to pass by without permanently damaging the counter crystal. The circuit comprises an RC circuit between the bias supply and the crystal with a reverse biased diode across the capacitor.

  16. Radiation damage and annealing of amorphous silicon solar cells

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Slemp, W. S.; Smith, B. T.; Buoncristiani, A. M.

    1984-01-01

    Amorphous silicon solar cells were irradiated with 1 MeV electrons at the Space Environmental Effects Laboratory of the NASA Langley Research Center. The cells accumulated a total fluence of 10 to the 14th, 10 to the 15th, and 10 to the 16th electrons per square centimeter and exhibited increasing degradation with each irradiation. This degradation was tracked by evaluating the I-V curves for AM0 illumination and the relative spectral response. The observed radiation damage was reversed following an anneal of the cells under vacuum at 200 C for 2 hours.

  17. A new mechanism for radiation damage processes in alkali halides

    NASA Astrophysics Data System (ADS)

    Dubinko, V. I.; Turkin, A. A.; Vainshtein, D. I.; den Hartog, H. W.

    1999-12-01

    We present a theory of radiation damage formation in alkali halides based on a new mechanism of dislocation climb, which involves the production of VF centers (self-trapped hole neighboring a cation vacancy) as a result of the absorption of H centers of dislocation lines. We consider the evolution of all experimentally observed extended defects: metal colloids, gas bubbles, and vacancy voids. Voids are shown to arise and grow large due to the reaction between F and VF centers at the surface of halogen bubbles. Voids can ignite a back reaction between the radiolytic products resulting in decomposition of the irradiated material.

  18. Simulation of neutron radiation damage in silicon semiconductor devices.

    SciTech Connect

    Shadid, John Nicolas; Hoekstra, Robert John; Hennigan, Gary Lee; Castro, Joseph Pete Jr.; Fixel, Deborah A.

    2007-10-01

    A code, Charon, is described which simulates the effects that neutron damage has on silicon semiconductor devices. The code uses a stabilized, finite-element discretization of the semiconductor drift-diffusion equations. The mathematical model used to simulate semiconductor devices in both normal and radiation environments will be described. Modeling of defect complexes is accomplished by adding an additional drift-diffusion equation for each of the defect species. Additionally, details are given describing how Charon can efficiently solve very large problems using modern parallel computers. Comparison between Charon and experiment will be given, as well as comparison with results from commercially-available TCAD codes.

  19. Mechanism for radiation damage resistance in yttrium oxide dispersion strengthened steels

    NASA Astrophysics Data System (ADS)

    Brodrick, J.; Hepburn, D. J.; Ackland, G. J.

    2014-02-01

    ODS steels based on yttrium oxide have been suggested as potential fusion reactor wall materials due to their observed radiation resistance properties. Presumably this radiation resistance can be related to the interaction of the particle with vacancies, self-interstitial atoms (SIAs) and other radiation damage debris. Density functional theory has been used to investigate this at the atomic scale. Four distinct interfaces, some based on HRTEM observations, between iron and yttrium oxide were investigated. It is been shown that the Y2O3-Fe interface acts as a strong trap with long-range attraction for both interstitial and vacancy defects, allowing recombination without altering the interface structure. The catalytic elimination of defects without change to the microstructure explains the improved behaviour of ODS steels with respect to radiation creep and swelling.

  20. Molecular dynamics simulation of radiation damage cascades in diamond

    SciTech Connect

    Buchan, J. T.; Robinson, M.; Christie, H. J.; Roach, D. L.; Ross, D. K.; Marks, N. A.

    2015-06-28

    Radiation damage cascades in diamond are studied by molecular dynamics simulations employing the Environment Dependent Interaction Potential for carbon. Primary knock-on atom (PKA) energies up to 2.5 keV are considered and a uniformly distributed set of 25 initial PKA directions provide robust statistics. The simulations reveal the atomistic origins of radiation-resistance in diamond and provide a comprehensive computational analysis of cascade evolution and dynamics. As for the case of graphite, the atomic trajectories are found to have a fractal-like character, thermal spikes are absent and only isolated point defects are generated. Quantitative analysis shows that the instantaneous maximum kinetic energy decays exponentially with time, and that the timescale of the ballistic phase has a power-law dependence on PKA energy. Defect recombination is efficient and independent of PKA energy, with only 50% of displacements resulting in defects, superior to graphite where the same quantity is nearly 75%.

  1. Medicinal protection with Chinese herb-compound against radiation damage

    SciTech Connect

    Zhang, R.J.; Qian, J.K.; Yang, G.H.; Wang, B.Z.; Wen, X.L. )

    1990-08-01

    Experiments were carried out on mice and the subjects irradiated for cancer therapy to evaluate the protective efficacy of a Chinese medicinal herb-compound (CMHC). The lethality and the degree of leucopenia caused by radiation in mice medicated with CMHC were significantly less in comparison with control mice (p less than 0.01 and p less than 0.001, respectively). CMHC significantly improved the WBC and the thrombocytes in irradiated workers (p less than 0.01 and p less than 0.001, respectively). The WBC count of 40 patients under radiotherapy while treated with CMHC recovered from 3450 +/- 77/c.mm to 5425 +/- 264/c.mm (p less than 0.001); whereas, in the control group, without any medication, the WBC count dropped significantly (p less than 0.001). Our results revealed the applicabilities of CMHC in protection against radiation damage in spaceflight and in other fields.

  2. Radiation-induced lung damage: dose-time-fractionation considerations.

    PubMed

    Van Dyk, J; Mah, K; Keane, T J

    1989-01-01

    The comparison of different dose-time-fractionation schedules requires the use of an isoeffect formula. In recent years, the NSD isoeffect formula has been heavily criticized. In this report, we consider an isoeffect formula which is specifically developed for radiation-induced lung damage. The formula is based on the linear-quadratic model and includes a factor for overall treatment time. The proposed procedures allow for the simultaneous derivation of an alpha/beta ratio and a gamma/beta time factor. From animal data in the literature, the derived alpha/beta and gamma/beta ratios for acute lung damage are 5.0 +/- 1.0 Gy and 2.7 +/- 1.4 Gy2/day respectively, while for late damage the suggested values are 2.0 Gy and 0.0 Gy2/day. Data from two clinical studies, one prospective and the other retrospective, were also analysed and corresponding alpha/beta and gamma/beta ratios were determined. For the prospective clinical study, with a limited range of doses per fraction, the resultant alpha/beta and gamma/beta ratios were 0.9 +/- 2.6 Gy and 2.6 +/- 2.5 Gy2/day. The combination of the retrospective and prospective data yielded alpha/beta and gamma/beta ratios of 3.3 +/- 1.5 Gy and 2.4 +/- 1.5 Gy2/day, respectively. One potential advantage of this isoeffect formalism is that it might possibly be applied to both acute and late lung damage. The results of this formulation for acute lung damage indicate that time-dependent effects such as slow repair or proliferation might be more important in determining isoeffect doses than previously predicted by the estimated single dose (ED) formula. Although we present this as an alternative approach, we would caution against its clinical use until its applicability has been confirmed by additional clinical data. PMID:2928557

  3. Proton irradiation of stem cells: Radiation damage and chemical radioprotection

    NASA Technical Reports Server (NTRS)

    Riley, R. C.; Montour, J. L.; Gurney, C. W.

    1972-01-01

    Effects of high energy protons on erythropoietic stem cells and radioprotection by chemicals were investigated in NASA Space Radiation Effects Laboratory. The effects of a parallel beam of 600 MeV protons. The fluence, when converted to dose, were referenced to the synchrocyclotron beam monitors which were then used to administer radiation exposures. Mice were given graded doses to 300 rads to determine dose-response curve. Other mice received saline, AET, or 5-hydroxytryptamine 10 to 15 minutes before exposure.

  4. Role of Oxidative Damage in Radiation-Induced Bone Loss

    NASA Technical Reports Server (NTRS)

    Schreurs, Ann-Sofie; Alwood, Joshua S.; Limoli, Charles L.; Globus, Ruth K.

    2014-01-01

    During prolonged spaceflight, astronauts are exposed to both microgravity and space radiation, and are at risk for increased skeletal fragility due to bone loss. Evidence from rodent experiments demonstrates that both microgravity and ionizing radiation can cause bone loss due to increased bone-resorbing osteoclasts and decreased bone-forming osteoblasts, although the underlying molecular mechanisms for these changes are not fully understood. We hypothesized that excess reactive oxidative species (ROS), produced by conditions that simulate spaceflight, alter the tight balance between osteoclast and osteoblast activities, leading to accelerated skeletal remodeling and culminating in bone loss. To test this, we used the MCAT mouse model; these transgenic mice over-express the human catalase gene targeted to mitochondria, the major organelle contributing free radicals. Catalase is an anti-oxidant that converts reactive species, hydrogen peroxide into water and oxygen. This animal model was selected as it displays extended lifespan, reduced cardiovascular disease and reduced central nervous system radio-sensitivity, consistent with elevated anti-oxidant activity conferred by the transgene. We reasoned that mice overexpressing catalase in mitochondria of osteoblast and osteoclast lineage cells would be protected from the bone loss caused by simulated spaceflight. Over-expression of human catalase localized to mitochondria caused various skeletal phenotypic changes compared to WT mice; this includes greater bone length, decreased cortical bone area and moment of inertia, and indications of altered microarchitecture. These findings indicate mitochondrial ROS are important for normal bone-remodeling and skeletal integrity. Catalase over-expression did not fully protect skeletal tissue from structural decrements caused by simulated spaceflight; however there was significant protection in terms of cellular oxidative damage (MDA levels) to the skeletal tissue. Furthermore, we

  5. Protecting the radiation-damaged skin from friction: a mini review

    PubMed Central

    Herst, Patries M

    2014-01-01

    Radiation-induced skin reactions are an unavoidable side effect of external beam radiation therapy, particularly in areas prone to friction and excess moisture such as the axilla, head and neck region, perineum and skin folds. Clinical studies investigating interventions for preventing or managing these reactions have largely focussed on formulations with moisturising, anti-inflammatory, anti-microbial and wound healing properties. However, none of these interventions has emerged as a consistent candidate for best practice. Much less emphasis has been placed on evaluating ways to protect the radiation-damaged skin from friction and excess moisture. This mini review analyses the clinical evidence for barrier products that form a protective layer by adhering very closely to the skin folds and do not cause further trauma to the radiation-damaged skin upon removal. A database search identified only two types of barrier products that fitted these criteria and these were tested in two case series and six controlled clinical trials. Friction protection was most effective when the interventions were used from the start of treatment and continued for several weeks after completion of treatment. Soft silicone dressings (Mepilex Lite and Mepitel Film) and Cavilon No Sting Barrier Film, but not Cavilon Moisturizing Barrier Cream, decreased skin reaction severity, most likely due to differences in formulation and skin build-up properties. It seems that prophylactic use of friction protection of areas at risk could be a worthwhile addition to routine care of radiation-damaged skin. PMID:26229646

  6. Protecting the radiation-damaged skin from friction: a mini review

    SciTech Connect

    Herst, Patries M

    2014-06-15

    Radiation-induced skin reactions are an unavoidable side effect of external beam radiation therapy, particularly in areas prone to friction and excess moisture such as the axilla, head and neck region, perineum and skin folds. Clinical studies investigating interventions for preventing or managing these reactions have largely focussed on formulations with moisturising, anti-inflammatory, anti-microbial and wound healing properties. However, none of these interventions has emerged as a consistent candidate for best practice. Much less emphasis has been placed on evaluating ways to protect the radiation-damaged skin from friction and excess moisture. This mini review analyses the clinical evidence for barrier products that form a protective layer by adhering very closely to the skin folds and do not cause further trauma to the radiation-damaged skin upon removal. A database search identified only two types of barrier products that fitted these criteria and these were tested in two case series and six controlled clinical trials. Friction protection was most effective when the interventions were used from the start of treatment and continued for several weeks after completion of treatment. Soft silicone dressings (Mepilex Lite and Mepitel Film) and Cavilon No Sting Barrier Film, but not Cavilon Moisturizing Barrier Cream, decreased skin reaction severity, most likely due to differences in formulation and skin build-up properties. It seems that prophylactic use of friction protection of areas at risk could be a worthwhile addition to routine care of radiation-damaged skin.

  7. Protecting the radiation-damaged skin from friction: a mini review.

    PubMed

    Herst, Patries M

    2014-06-01

    Radiation-induced skin reactions are an unavoidable side effect of external beam radiation therapy, particularly in areas prone to friction and excess moisture such as the axilla, head and neck region, perineum and skin folds. Clinical studies investigating interventions for preventing or managing these reactions have largely focussed on formulations with moisturising, anti-inflammatory, anti-microbial and wound healing properties. However, none of these interventions has emerged as a consistent candidate for best practice. Much less emphasis has been placed on evaluating ways to protect the radiation-damaged skin from friction and excess moisture. This mini review analyses the clinical evidence for barrier products that form a protective layer by adhering very closely to the skin folds and do not cause further trauma to the radiation-damaged skin upon removal. A database search identified only two types of barrier products that fitted these criteria and these were tested in two case series and six controlled clinical trials. Friction protection was most effective when the interventions were used from the start of treatment and continued for several weeks after completion of treatment. Soft silicone dressings (Mepilex Lite and Mepitel Film) and Cavilon No Sting Barrier Film, but not Cavilon Moisturizing Barrier Cream, decreased skin reaction severity, most likely due to differences in formulation and skin build-up properties. It seems that prophylactic use of friction protection of areas at risk could be a worthwhile addition to routine care of radiation-damaged skin. PMID:26229646

  8. Identifying and quantifying radiation damage at the atomic level

    PubMed Central

    Gerstel, Markus; Deane, Charlotte M.; Garman, Elspeth F.

    2015-01-01

    Radiation damage impedes macromolecular diffraction experiments. Alongside the well known effects of global radiation damage, site-specific radiation damage affects data quality and the veracity of biological conclusions on protein mechanism and function. Site-specific radiation damage follows a relatively predetermined pattern, in that different structural motifs are affected at different dose regimes: in metal-free proteins, disulfide bonds tend to break first followed by the decarboxylation of aspartic and glutamic acids. Even within these damage motifs the decay does not progress uniformly at equal rates. Within the same protein, radiation-induced electron density decay of a particular chemical group is faster than for the same group elsewhere in the protein: an effect known as preferential specific damage. Here, B Damage, a new atomic metric, is defined and validated to recognize protein regions susceptible to specific damage and to quantify the damage at these sites. By applying B Damage to a large set of known protein structures in a statistical survey, correlations between the rates of damage and various physicochemical parameters were identified. Results indicate that specific radiation damage is independent of secondary protein structure. Different disulfide bond groups (spiral, hook, and staple) show dissimilar radiation damage susceptibility. There is a consistent positive correlation between specific damage and solvent accessibility. PMID:25723922

  9. Radiation Damage Effects in Far Ultraviolet Filters and Substrates

    NASA Technical Reports Server (NTRS)

    Keffer, Charles E.; Torr, Marsha R.; Zukic, Muamer; Spann, James F.; Torr, Douglas G.; Kim, Jongmin

    1993-01-01

    New advances in VUV thin film filter technology have been made using filter designs with multilayers of materials such as Al2O3, BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2. Our immediate application for these filters will be in an imaging system to be flown on a satellite where a 2 X 9 R(sub E) orbit will expose the instrument to approximately 275 krads of radiation. In view of the fact that no previous studies have been made on potential radiation damage of these materials in the thin film format, we report on such an assessment here. Transmittances and reflectances of BaF2, CaF2, HfO2, LaF3, MgF2, and SiO2 thin films on MgF2 substrates, Al2O3 thin films on fused silica substrates, uncoated fused silica and MgF2, and four multilayer filters made from these materials were measured from 120 nm to 180 nm before and after irradiation by 250 krads from a Co-60 gamma radiation source. No radiation-induced losses in transmittance or reflectance occurred in this wavelength range. Additional postradiation measurements from 160 nm to 300 nm indicated a 3 - 5% radiation-induced absorption near 260 nm in some of the samples with MgF2 substrates. From these measurements it is concluded that far ultraviolet filters made from the materials tested should experience less that 5% change from exposure to up to 250 krads of high energy radiation in space applications.

  10. A Simplified Algorithm for Statistical Investigation of Damage Spreading

    SciTech Connect

    Gecow, Andrzej

    2009-04-16

    On the way to simulating adaptive evolution of complex system describing a living object or human developed project, a fitness should be defined on node states or network external outputs. Feedbacks lead to circular attractors of these states or outputs which make it difficult to define a fitness. The main statistical effects of adaptive condition are the result of small change tendency and to appear, they only need a statistically correct size of damage initiated by evolutionary change of system. This observation allows to cut loops of feedbacks and in effect to obtain a particular statistically correct state instead of a long circular attractor which in the quenched model is expected for chaotic network with feedback. Defining fitness on such states is simple. We calculate only damaged nodes and only once. Such an algorithm is optimal for investigation of damage spreading i.e. statistical connections of structural parameters of initial change with the size of effected damage. It is a reversed-annealed method--function and states (signals) may be randomly substituted but connections are important and are preserved. The small damages important for adaptive evolution are correctly depicted in comparison to Derrida annealed approximation which expects equilibrium levels for large networks. The algorithm indicates these levels correctly. The relevant program in Pascal, which executes the algorithm for a wide range of parameters, can be obtained from the author.

  11. Spectroscopic investigation on protein damage by ciprofloxacin under ultrasonic irradiation

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Wang, Dong-Jing; Wang, Xin; Liu, Bing-Mi; Kong, Yu-Mei; He, Ling-Ling; Wang, Jun; Xu, Shu-Kun

    2011-02-01

    In recent years, sonodynamic activities of many drugs have attracted more and more attention of researchers. The correlative study will promote the development of sonodynamic therapy (SDT) in anti-tumor treatment. In this work, bovine serum albumin (BSA) was used as a protein model to investigate the intensifying effects of ciprofloxacin (CPFX) ultrasonically induced protein damage by UV-vis and fluorescence spectra. Meanwhile, the conformation of BSA is changed upon the addition of CPFX and metal ions under ultrasound (US) so that the damaging site of BSA is considered. Various influencing factors, such as US irradiation time, metal ions, solution temperature and ionic strength, on the ultrasonically induced BSA damage are discussed. It was showed that CPFX could enhance ultrasonically induced BSA damage. The damage degree of BSA was aggravated with the increasing of US irradiation time, solution temperature, ionic strength as well as the addition of metal ions. Furthermore, the reactive oxygen species (ROS) in reaction system were detected by oxidation-extraction photometry (OEP). Experimental results also showed that US could activate CPFX to produce ROS, which were mainly determined as superoxide radical anion ( rad O 2-) and hydroxyl radical ( rad OH).

  12. Grad-Level Radiation Damage of SIO2 Detectors

    SciTech Connect

    Simos, N.; Atoian, G.; Ludewig, H; White, S; O'Conor, J; Mokhov, N.V.

    2009-05-04

    Radiation effects and levels to detectors. SiO{sub 2} quartz fibers of the LHC ATLAS Zero-degree Calorimeter (ZDC) anticipated to experience integrated doses of a few Grad at their closest position were exposed to 200 MeV protons and neutrons at the Brookhaven National Laboratory (BNL) Linac. Specifically, 1 mm- and 2mm-diameter quartz (GE 124) rods were exposed to direct 200 MeV protons during the first phase of exposure leading to peak integrated dose of {approx}28 Grad. Exposure to a primarily neutron flux of 1mm-diameter SiO{sub 2} fibers was also achieved with a special neutron source arrangement. In a post-irradiation analysis the quartz fiber transmittance was evaluated as a function of the absorbed dose. Dramatic degradation of the transmittance property was observed with increased radiation damage. In addition, detailed evaluation of the fibers under the microscope revealed interesting micro-structural damage features and irradiation-induced defects.

  13. Imperfection and radiation damage in protein crystals studied with coherent radiation

    PubMed Central

    Nave, Colin; Sutton, Geoff; Evans, Gwyndaf; Owen, Robin; Rau, Christoph; Robinson, Ian; Stuart, David Ian

    2016-01-01

    Fringes and speckles occur within diffraction spots when a crystal is illuminated with coherent radiation during X-ray diffraction. The additional information in these features provides insight into the imperfections in the crystal at the sub-micrometre scale. In addition, these features can provide more accurate intensity measurements (e.g. by model-based profile fitting), detwinning (by distinguishing the various components), phasing (by exploiting sampling of the molecular transform) and refinement (by distinguishing regions with different unit-cell parameters). In order to exploit these potential benefits, the features due to coherent diffraction have to be recorded and any change due to radiation damage properly modelled. Initial results from recording coherent diffraction at cryotemperatures from polyhedrin crystals of approximately 2 µm in size are described. These measurements allowed information about the type of crystal imperfections to be obtained at the sub-micrometre level, together with the changes due to radiation damage. PMID:26698068

  14. Positron annihilation lifetime study of radiation-damaged natural zircons

    NASA Astrophysics Data System (ADS)

    Roberts, J.; Gaugliardo, P.; Farnan, I.; Zhang, M.; Vance, E. R.; Davis, J.; Karatchevtseva, I.; Knott, R. B.; Mudie, S.; Buckman, S. J.; Sullivan, J. P.

    2016-04-01

    Zircons are a well-known candidate waste form for actinides and their radiation damage behaviour has been widely studied by a range of techniques. In this study, well-characterised natural single crystal zircons have been studied using Positron Annihilation Lifetime Spectroscopy (PALS). In some, but not all, of the crystals that had incurred at least half of the alpha-event damage of ∼1019 α/g required to render them structurally amorphous, PALS spectra displayed long lifetimes corresponding to voids of ∼0.5 nm in diameter. The long lifetimes corresponded to expectations from published Small-Angle X-ray Scattering data on similar samples. However, the non-observation by PALS of such voids in some of the heavily damaged samples may reflect large size variations among the voids such that no singular size can be distinguished or. Characterisation of a range of samples was also performed using scanning electron microscopy, optical absorption spectroscopy, Raman scattering and X-ray scattering/diffraction, with the degree of alpha damage being inferred mainly from the Raman technique and X-ray diffraction. The observed void diameters and intensities of the long lifetime components were changed somewhat by annealing at 700 °C; annealing at 1200 °C removed the voids entirely. The voids themselves may derive from He gas bubbles or voids created by the inclusion of small quantities of organic and hydrous matter, notwithstanding the observation that no voidage was evidenced by PALS in two samples containing hydrous and organic matter.

  15. Study of the effect of dose-rate on radiation-induced damage to human erythrocytes

    NASA Astrophysics Data System (ADS)

    Krokosz, Anita; Koziczak, Renata; Gonciarz, Marta; Szweda-Lewandowska, Zofia

    2006-01-01

    Human erythrocytes suspended in an isotonic Na-phosphate buffer, pH 7.4 (hematocrit of 2%) were irradiated with γ-rays at three dose-rates of 66.7, 36.7, 25 Gy min -1 in order to investigate the influence of the dose-rate on radiation-induced membrane damage, hemoglobin oxidation and loss of reduced glutathione. The obtained results showed that such processes as erythrocyte hemolysis, lipid and protein destruction depend on the radiation dose-rate. The parameter values describing these processes showed an inverse dose-rate effect.

  16. Nanocrystal Ghosting: Extensive radiation damage in MgO induced by low-energy electrons

    NASA Astrophysics Data System (ADS)

    Sawyer, William; Frankenfield, Zachery; Kane, Kenneth

    Radiation damage in magnesium oxide has been an ongoing source of investigation. Early work was motivated by its simple cubic structure and its excellent electrical insulating properties over a wide range of temperatures and mechanical conditions. The goal was to determine its suitability as an electrical insulator in radiation intense environments including nuclear reactors and proposed nuclear fusion devices. During this period experimental results for irradiation of MgO using electrons with energies less than 500 keV produced very limited damage. These results, supported by theoretical arguments, lead to the conclusion that MgO was relatively impervious to damage from electrons with energies below this threshold. More recently its excellent insulating properties and relative mechanical stability combined with an increased interest in nanomaterials applications have created renewed interest in MgO. In this paper direct evidence is presented for extensive radiation damage in MgO nanocrystals from intense irradiation by electrons (2 x 10 4electrons/nm2 sec) with beam energies between 120 keV and 60 keV.

  17. The interaction of melanin with ionizing and UVC radiations: Characterization of thymine damage

    SciTech Connect

    Huselton, C.A.

    1988-01-01

    These studies were undertaken to determine whether melanin could protect DNA against the harmful effects of ionizing or UVC radiations. A simple, in vitro, model system was developed to evaluate eumelanin (Sigma melanin) as a radioprotector of solutions of 0.1 mM thymine or thymidine exposed to 570Gy of ionizing radiation. Sigma melanin was compared to several amino acids, other biomolecules or to other forms of melanin. To investigate the role of melanin as a passive screen of UVC radiation, melanotic (I{sub 3}), amelanotic (AMEL) cells (both derived from a Cloudman S91 melanoma) and non-melanotic (EMT6) cells were labelled with radioactive dTHd and exposed to 0, 1, 5 or 10KJ/m{sup 2} of UVC. The DNA was extracted; the bases hydrolyzed with concentrated HCl. Thymine bases were separated by reverse phase HPLC. No difference in dimer content was observed between I{sub 3} and AMEL cells, but EMT6 cells had nearly twice the amount of dimer. Overall thymine degradation was more pronounced in I{sub 3} cells than in the other two cell lines, due to the production of non-dimer thymine damage. This damage was identified as thymine glycol by HPLC and mass spectrometry. Melanin, upon exposure to UVC, appears to enhance thymine damage by producing oxidative damage.

  18. Use of Displacement Damage Dose in an Engineering Model of GaAs Solar Cell Radiation Damage

    NASA Technical Reports Server (NTRS)

    Morton, T. L.; Chock, R.; Long, K. J.; Bailey, S.; Messenger, S. R.; Walters, R. J.; Summers, G. P.

    2005-01-01

    Current methods for calculating damage to solar cells are well documented in the GaAs Solar Cell Radiation Handbook (JPL 96-9). An alternative, the displacement damage dose (D(sub d)) method, has been developed by Summers, et al. This method is currently being implemented in the SAVANT computer program.

  19. Early and Late Damages in Chromosome 3 of Human Lymphocytes After Radiation Exposure

    NASA Technical Reports Server (NTRS)

    Sunagawa, Mayumi; Mangala, Lingegowda; Zhang, Ye; Kahdim, Munira; Wilson, Bobby; Cucinotta, Francis A.; Wu, Honglu

    2011-01-01

    Tumor formation in humans or animals is a multi-step process. An early stage of cancer development is believed to be genomic instability (GI) which accelerates the mutation rate in the descendants of the cells surviving radiation exposure. GI is defined as elevated or persistent genetic damages occurring many generations after the cells are exposed. While early studies have demonstrated radiation-induced GI in several cell types as detected in endpoints such as mutation, apoptosis and damages in chromosomes, the dependence of GI on the quality of radiation remains uncertain. To investigate GI in human lymphocytes induced by both low- and high-LET radiation, we initially exposed white blood cells collected from healthy subjects to gamma rays in vitro, and cultured the cells for multiple generations. Chromosome aberrations were analyzed in cells collected at first mitosis post irradiation and at several intervals during the culture period. Among a number of biological endpoints planned for the project, the multi-color banding fluorescent in situ hybridization (mBAND) allows identification of inversions that were expected to be stable. We present here early and late chromosome aberrations detected with mBAND in chromosome 3 after gamma exposure. Comparison of chromosome damages in between human lymphocytes and human epithelial cells is also discussed

  20. High and Low LET Radiation Differentially Induce Normal Tissue Damage Signals

    SciTech Connect

    Niemantsverdriet, Maarten; Goethem, Marc-Jan van; Bron, Reinier; Hogewerf, Wytse; Brandenburg, Sytze; Langendijk, Johannes A.; Luijk, Peter van; Coppes, Robert P.

    2012-07-15

    Purpose: Radiotherapy using high linear energy transfer (LET) radiation is aimed at efficiently killing tumor cells while minimizing dose (biological effective) to normal tissues to prevent toxicity. It is well established that high LET radiation results in lower cell survival per absorbed dose than low LET radiation. However, whether various mechanisms involved in the development of normal tissue damage may be regulated differentially is not known. Therefore the aim of this study was to investigate whether two actions related to normal tissue toxicity, p53-induced apoptosis and expression of the profibrotic gene PAI-1 (plasminogen activator inhibitor 1), are differentially induced by high and low LET radiation. Methods and Materials: Cells were irradiated with high LET carbon ions or low LET photons. Cell survival assays were performed, profibrotic PAI-1 expression was monitored by quantitative polymerase chain reaction, and apoptosis was assayed by annexin V staining. Activation of p53 by phosphorylation at serine 315 and serine 37 was monitored by Western blotting. Transfections of plasmids expressing p53 mutated at serines 315 and 37 were used to test the requirement of these residues for apoptosis and expression of PAI-1. Results: As expected, cell survival was lower and induction of apoptosis was higher in high -LET irradiated cells. Interestingly, induction of the profibrotic PAI-1 gene was similar with high and low LET radiation. In agreement with this finding, phosphorylation of p53 at serine 315 involved in PAI-1 expression was similar with high and low LET radiation, whereas phosphorylation of p53 at serine 37, involved in apoptosis induction, was much higher after high LET irradiation. Conclusions: Our results indicate that diverse mechanisms involved in the development of normal tissue damage may be differentially affected by high and low LET radiation. This may have consequences for the development and manifestation of normal tissue damage.

  1. Rapamycin‐induced autophagy sensitizes A549 cells to radiation associated with DNA damage repair inhibition

    PubMed Central

    Li, Yong; Liu, Fen; Wang, Yong; Li, Donghai; Guo, Fei; Xu, Liyao; Zeng, Zhengguo; Zhong, Xiaojun

    2016-01-01

    Abstract Background Autophagy has been reported to increase in cancer cells after radiation. However, it remains unknown whether increased autophagy as a result of radiation affects DNA damage repair and sensitizes cancer cells. In this study, the radiosensitization effect of rapamycin, a mammalian target of rapamycin inhibitor that induces autophagy, on human lung adenocarcinoma A549 cells was investigated. Methods A549 cells were treated with different concentrations of rapamycin. Cell viability was evaluated by methyl‐thiazolyl‐tetrazolium assay. Survival fraction values of A549 cells after radiotherapy were detected by colony formation assay. Autophagosome was observed by a transmission electron microscope. Furthermore, Western blot was employed to examine alterations in autophagy protein LC3 and p62, DNA damage protein γ–H2AX, and DNA damage repair proteins Rad51, Ku70, and Ku80. Rad51, Ku70, and Ku80 messenger ribonucleic acid (mRNA) expression levels were examined by real‐time polymerase chain reaction. Results Rapamycin suppressed A549 cell proliferation in dose and time‐dependent manners. An inhibitory concentration (IC) 10 dose of rapamycin could induce autophagy in A549 cells. Rapamycin combined with radiation significantly decreased the colony forming ability of cells, compared with rapamycin or radiation alone. Rapamycin and radiation combined increased γ–H2AX expression levels and decreased Rad51 and Ku80 expression levels, compared with single regimens. However, rapamycin treatment did not induce any change in Rad51, Ku70, and Ku80 mRNA levels, regardless of radiation. Conclusions These findings indicate that increasing autophagy sensitizes lung cancer cells to radiation. PMID:27385978

  2. Radiation Damage on Multiple Length Scales in Uranium Dioxide

    NASA Astrophysics Data System (ADS)

    Gupta, Mahima

    Radiation damage in UO2 has been well studied but there exists little correlation between point defect accumulation, lattice structure changes and microstructure. This is partly because irradiated nuclear fuel is highly radioactive and its defect chemistry is extremely complicated resulting from fission of the material and consequent fission products being embedded in the fuel matrix [Olander1976]. To adequately study the evolution of defects from point defects through to microstructure features, the resulting defects have to be intentionally simplified for characterization. Ion accelerators have the unique capability of creating simple microstructure features using specific ions, without the added complication of fission and neutron activation from nuclear reactors. As an example, H+ ions have been used to create (only) a distribution of dislocations that were studied using various techniques. The ability to tune the energy or type of the ion to achieve desirable implantation depth and ideally simple microstructure renders it a lucrative instrument for this type of analysis. X-ray diffraction (XRD) studies and transmission electron microscopy (TEM) have been utilized to study extended structure changes and microstructure evolution. Ion beam irradiations create displacements and displacement networks, voids, surface fracturing, gas bubbles and several other microstructure changes to model nuclear reactor damage [Noris1972]. Using an ion accelerator, it has been possible to isolate these radiation induced defects and study their subsequent evolution with increasing dose. Insofar, since all of the phenomena caused by radiation damage originate from point defects, the elucidation of radiation effects on the atomic scale is crucial. This is rendered complicated due to aperiodic irradiation defects. This lack of periodicity renders standard approaches, such as TEM and XRD ineffective, as these methods probe average structure over tens of Angstroms. Therefore, techniques

  3. Development of resistant materials to beam impact and radiation damage

    NASA Astrophysics Data System (ADS)

    Kawai, Masayoshi; Kokawa, Hiroyuki; Okamura, Hiroshi; Kawasaki, Akira; Yamamura, Tsutomu; Hara, Nobuyoshi; Akao, Noboru; Futakawa, Masatoshi; Kikuchi, Kenji

    2006-09-01

    Materials that have strong resistance to both beam impact (or shock-wave) and radiation damage are required for the beam target of an intense accelerator and space applications. Recently, Futakawa et al. found in their experiments that Kolsterising specimens have a stronger resistance to pitting than SS316 CW. A similar effect can be expected for other hardening treatments, and new material development is hopeful. Accordingly, we have started the development of high-performance materials by organizing the project team from KEK, JAEA and universities. In this paper, the scope of the project is introduced. Recent topics involve the development of intergranular crack (IGC)-resistant austenitic stainless-steel, AlN-TiN ceramics and cladding techniques of thin tantalum or CrN film on a tungsten target by means of a molten-salt method and ion-beam-enhanced deposition. New observations on corrosion resistance are presented.

  4. Weak-localization effect in superconductors from radiation damage

    NASA Astrophysics Data System (ADS)

    Park, Mi-Ae; Kim, Yong-Jihn

    2000-06-01

    Large reductions of the superconducting transition temperature Tc and the accompanying loss of the thermal electrical resistivity (electron-phonon interaction) due to radiation damage have been observed for several A15 compounds, Chevrel phase and ternary superconductors, and NbSe2 in the high-fluence regime. We examine these behaviors based on a recent theory of the weak localization effect in superconductors. We find a good fitting to the experimental data. In particular, the weak localization correction to the phonon-mediated interaction is derived from the density correlation function. It is shown that weak localization has a strong influence on both the phonon-mediated interaction and the electron-phonon interaction, which leads to the universal correlation of Tc and the resistance ratio.

  5. Chromatin Compaction Protects Genomic DNA from Radiation Damage

    PubMed Central

    Takata, Hideaki; Hanafusa, Tomo; Mori, Toshiaki; Shimura, Mari; Iida, Yutaka; Ishikawa, Kenichi; Yoshikawa, Kenichi; Yoshikawa, Yuko; Maeshima, Kazuhiro

    2013-01-01

    Genomic DNA is organized three-dimensionally in the nucleus, and is thought to form compact chromatin domains. Although chromatin compaction is known to be essential for mitosis, whether it confers other advantages, particularly in interphase cells, remains unknown. Here, we report that chromatin compaction protects genomic DNA from radiation damage. Using a newly developed solid-phase system, we found that the frequency of double-strand breaks (DSBs) in compact chromatin after ionizing irradiation was 5–50-fold lower than in decondensed chromatin. Since radical scavengers inhibited DSB induction in decondensed chromatin, condensed chromatin had a lower level of reactive radical generation after ionizing irradiation. We also found that chromatin compaction protects DNA from attack by chemical agents. Our findings suggest that genomic DNA compaction plays an important role in maintaining genomic integrity. PMID:24130727

  6. Proton radiation damage in bulk n-GaAs

    NASA Technical Reports Server (NTRS)

    Liu, D. C.; Blue, J. W.; Flood, D. J.; Stanchina, W. E.

    1980-01-01

    Bulk samples of Te-doped n-type GaAs were irradiated using 10 MeV to 24 MeV protons to fluences between 2 x 10 to the 11th power protons/sq cm and 2 x 10 to the 14th power protons/sq cm. Majority carrier electrical effects were measured using the vanderPauw techniques and it was observed that radiation damage was minimal at the 10 to the 11th power proton/sq cm fluence. For the higher fluences, carrier removal was proportional to Delta E/Delta x for the protons indicating ionization interactions between the protons and atoms. Thermal annealing was observed at 155 C.

  7. Dislocation dynamics modelling of radiation damage in thin films

    NASA Astrophysics Data System (ADS)

    Ferroni, Francesco; Tarleton, Edmund; Fitzgerald, Steven

    2014-06-01

    Transmission electron microscopy is a key tool for the extraction of information on radiation damage, the understanding of which is critical for materials development for nuclear fusion and fission reactors. Dislocations in TEM samples are subject to strong image forces, owing to the nanometric sample thicknesses, which may introduce artifacts in the damage analysis. Using dislocation dynamics, we elucidate the roles played by dislocation-surface interactions, dislocation-dislocation interactions and self-interactions due to climb for loop types observed in TEM. Comparisons with analytic solutions for a dislocation loop and an edge dislocation in a half-space are included, and the relationship between glide force and loop tilt examined. The parameters for convergence of the zero-traction boundary conditions are obtained, after which the evolution of dislocation structures in a thin film is studied. It is found that three main length scales govern the physical processes: the image force is governed by the distance of the loop from the surface and scales with the film thickness; the glide force is governed by the image stress as well as the loop-loop interaction stress which is in turn governed by the loop spacing L\\sim 1/\\sqrt{\\rho} , where ρ is the loop density; finally, the climb force depends on the loop size. The three forces compete and their relative magnitudes define the evolution pathway of the dislocation structure.

  8. Effect of electron excitation on radiation damage in fce metals

    NASA Astrophysics Data System (ADS)

    Iwase, A.; Iwata, T.

    1994-05-01

    Defect production, radiation annealing and defect recovery are studied in several fcc metals (Al, Cu, Ni, Ag and Pt) irradiated with low-energy (˜ 1 MeV) and high-energy (˜ 100 MeV) ions. Irradiation of the metals with strong electron-lattice interaction (Al, Ni and Pt) by ˜ 100 MeV ions causes an anomalous reduction, or even a complete disappearance of stage-I recovery. This experimental result shows that the energy transferred from excited electrons to lattice atoms through the electron-lattice interaction contributes to the annihilation of single interstitials. This effect is also observed in Ni as a large cross section for radiation annealing, and a decrease of the damage efficiency. On the other hand, in Cu and Ag thin foils, we find that lattice defects are produced not only through elastic interactions, but also through a process strongly associated with electron excitation. In the latter process, the defect production cross section is proportional to Se1.7 in Cu and Se1.5 in Ag. The nearly quadratic dependence of the cross section on Se suggests that the mutual Coulomb repulsion of ions positively charged by electron excitation causes the defect production.

  9. Investigating Science Literacy: Students' Conceptions of Radiation

    NASA Astrophysics Data System (ADS)

    Romine, James; Buxner, S.; Impey, C. D.; Nieberding, M. N.; Antonellis, J. C.; Collaborations of Astronomy Teaching Scholars (CATS)

    2014-01-01

    This study is part of a larger investigation of students' science literacy in which we have been collecting survey data from undergraduate students enrolled in introductory science courses from 1980-2013. The overall survey asks students questions about basic topics in science and technology. We present results from the analysis of students' open-ended responses to the question "What is radiation?" Our findings show that a substantial number of students' perceptions of radiation are focused on the dangers of radiation and less on the applications. A large fraction of students correctly identified radiation as energy or light, although they expressed the misconception that only part of the electromagnetic spectrum counted as radiation. Overall, students expressed a number of misconceptions about the sources and uses of radiation although over 80% know that radiation can occur naturally or be man made. We present how these findings relate to other large trends from the survey. This material is based in part upon work supported by the National Science Foundation under Grant No. 0715517, a CCLI Phase III Grant for the Collaboration of Astronomy Teaching Scholars (CATS). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

  10. Acute radiation-induced pulmonary damage: a clinical study on the response to fractionated radiation therapy.

    PubMed

    Mah, K; Van Dyk, J; Keane, T; Poon, P Y

    1987-02-01

    Acute radiation-induced pulmonary damage can be a significant cause of morbidity in radiation therapy of the thorax. A prospective, clinical study was conducted to obtain dose-response data on acute pulmonary damage caused by fractionated radiation therapy. The endpoint was a visible increase in lung density within the irradiated volume on a computed tomographic (CT) examination as observed independently by three diagnostic radiologists. Fifty-four patients with various malignancies of the thorax completed the study. CT chest scans were taken before and at preselected times following radiotherapy. To represent different fractionation schedules of equivalent biological effect, the estimated single dose (ED) model, ED = D X N-0.377 X T-0.058 was used in which D was the average lung dose within the high dose region in cGy, N was the number of fractions, and T was the overall treatment time in days. Patients were grouped according to ED and the percent incidence of pulmonary damage for each group was determined. Total average lung doses ranged from 29.8 Gy to 53.6 Gy given in 10 to 30 fractions over a range of 12 to 60 days. Five patient groups with incidence ranging from 30% (ED of 930) to 90% (ED of 1150) were obtained. The resulting dose-response curve predicted a 50% incidence level at an ED value (ED50) of 1000 +/- 40 ED units. This value represents fractionation schedules equivalent to a total average lung dose of 32.9 Gy given in 15 fractions over 19 days. Over the linear portion of the dose-response curve, a 5% increase in ED (or total dose if N and T remain constant), predicts a 12% increase in the incidence of acute radiation-induced pulmonary damage. PMID:3818385

  11. Investigation of Moving Belt Radiator Technology Issues

    NASA Technical Reports Server (NTRS)

    Teagan, W. Peter; Aguilar, Jerry L.

    1994-01-01

    The development of an advanced spacecraft radiator technology is reported. The moving belt radiator is a thermal radiator concept with the promise of lower specific mass (per kW rejected) than that afforded by existing technologies. The results of a parametric study to estimate radiator mass for future space power systems is presented. It is shown that this technology can be scaled up to 200 MW for higher rejection temperatures. Several aspects of the design concept are discussed, including the dynamics of a large rotating belt in microgravity. The results of a computer code developed to model the belt dynamics are presented. A series of one-g experiments to investigate the dynamics of small belts is described. A comprehensive test program to investigate belt dynamics in microgravity aboard the NASA KC-135 aircraft is discussed. It was found that the desired circular shape can readily be achieved in microgravity. It is also shown that a rotating belt is stable when subjected to simulated attitude control maneuvers. Heat exchanger design is also investigated. Several sealing concepts were examined experimentally, and are discussed. Overall heat transfer coefficients to the rotating belt are presented. Material properties for various belt materials, including screen meshes, are also presented. The results presented in this report indicate that the moving belt radiator concept is technically feasible.

  12. Experimental studies of radiation damage of silicon detectors. Internal report

    SciTech Connect

    Angelescu, T.; Ghete, V.M.; Ghiordanescu, N.; Lazanu, I.; Mihul, A.; Golutvin, I.; Lazanu, S.; Savin, I.; Vasilescu, A.; Biggeri, U.; Borchi, E.; Bruzzi, M. |; Li, Z.; Kraner, H.W.

    1994-02-01

    New particle physics experiments are correlated with high luminosity and/or high energy. The new generation of colliding beam machines which will be constructed will make an extrapolation of a factor of 100 in the center of mass energy and of 1000 in luminosity beyond present accelerators. The scientific community hopes that very exciting physics results could be achieved this way, from the solution to the problem of electroweak symmetry breaking to the possible discovery of new, unpredicted phenomena. The particles which compose the radiation field are: electrons, pions, neutrons, protons and photons. It has become evident that the problem of the radiation resistance of detectors in this severe environment is a crucial one. This situation is complicated more by the fact that detectors must work all the run time of the machine, and better all the time of the experiment, without replacement (part or whole). So, studies related to the investigation of the radiation hardness of all detector parts, are developing. The studies are in part material and device characterization after irradiation, and in part technological developments, made in order to find harder, cheaper technologies, for larger surfaces. Semiconductor detectors have proven to be a good choice for vertex and calorimeter. Both fixed target machines and colliders had utilized in the past silicon junction detectors as the whole or part of the detection system. Precision beam hodoscopes and sophisticated trigger devices with silicon are equally used. The associated electronics in located near the detectors, and is subjected to the same radiation fields. Studies of material and device radiation hardness are developing in parallel. Here the authors present results on the radiation hardness of silicon, both as a bulk material and as detectors, to neutron irradiation at high fluences.

  13. Radiation damage in MOS integrated circuits, Part 1

    NASA Technical Reports Server (NTRS)

    Danchenko, V.

    1971-01-01

    Complementary and p-channel MOS integrated circuits made by four commercial manufacturers were investigated for sensitivity to radiation environment. The circuits were irradiated with 1.5 MeV electrons. The results are given for electrons and for the Co-60 gamma radiation equivalent. The data are presented in terms of shifts in the threshold potentials and changes in transconductances and leakages. Gate biases of -10V, +10V and zero volts were applied to individual MOS units during irradiation. It was found that, in most of circuits of complementary MOS technologies, noticable changes due to radiation appear first as increased leakage in n-channel MOSFETs somewhat before a total integrated dose 10 to the 12th power electrons/sg cm is reached. The inability of p-channel MOSFETs to turn on sets in at about 10 to the 13th power electrons/sq cm. Of the circuits tested, an RCA A-series circuit was the most radiation resistant sample.

  14. A Role for Lsm1p in Response to Ultraviolet-Radiation Damage in Saccharomyces cerevisiae

    PubMed Central

    Spicakova, Tatiana; McCann, Kelly; Brown, J. Martin

    2008-01-01

    A genome-wide screen in Saccharomyces cerevisiae identified LSM1 as a new gene affecting sensitivity to ultraviolet (UV) radiation. Lsm1p is a member of a cytoplasmic complex composed of Lsm1p–7p that interacts with the yeast mRNA degradation machinery. To investigate the potential role of Lsm1p in response to UV radiation, we constructed double mutant strains in which LSM1 was deleted in combination with a representative gene from each of three known yeast DNA repair pathways. Our results show that lsm1Δ increases the UV-radiation sensitivity of the rad1Δ and rad51Δ mutants, but not the rad18Δ mutant, placing LSM1 within the post-replication repair/damage tolerance pathway (PRR). When combined with other deletions affecting PRR, lsm1Δ increases the UV-radiation sensitivity of the rev3Δ, rad30Δ and pol30-K164R mutants but not rad5Δ. Furthermore, the UV-radiation sensitivity phenotype of lsm1Δ is partially rescued by mutations in genes involved in 3′ to 5′ mRNA degradation, and mutations predicted to function in RNA interactions confer the most UV-radiation sensitivity. Together, these results suggest that Lsm1p may confer protection against UV-radiation damage by protecting the 3′ ends of mRNAs from exosome-dependent 3′ to 5′ degradation as part of a novel RAD5-mediated, PCNA-K164 ubiquitylation-independent subpathway of PRR. PMID:19024647

  15. Dissecting the molecular mechanism of ionizing radiation-induced tissue damage in the feather follicle.

    PubMed

    Chen, Xi; Liao, Chunyan; Chu, Qiqi; Zhou, Guixuan; Lin, Xiang; Li, Xiaobo; Lu, Haijie; Xu, Benhua; Yue, Zhicao

    2014-01-01

    Ionizing radiation (IR) is a common therapeutic agent in cancer therapy. It damages normal tissue and causes side effects including dermatitis and mucositis. Here we use the feather follicle as a model to investigate the mechanism of IR-induced tissue damage, because any perturbation of feather growth will be clearly recorded in its regular yet complex morphology. We find that IR induces defects in feather formation in a dose-dependent manner. No abnormality was observed at 5 Gy. A transient, reversible perturbation of feather growth was induced at 10 Gy, leading to defects in the feather structure. This perturbation became irreversible at 20 Gy. Molecular and cellular analysis revealed P53 activation, DNA damage and repair, cell cycle arrest and apoptosis in the pathobiology. IR also induces patterning defects in feather formation, with disrupted branching morphogenesis. This perturbation is mediated by cytokine production and Stat1 activation, as manipulation of cytokine levels or ectopic Stat1 over-expression also led to irregular feather branching. Furthermore, AG-490, a chemical inhibitor of Stat1 signaling, can partially rescue IR-induced tissue damage. Our results suggest that the feather follicle could serve as a useful model to address the in vivo impact of the many mechanisms of IR-induced tissue damage. PMID:24586618

  16. Structural investigation of self-irradiation damaged AmO2

    NASA Astrophysics Data System (ADS)

    Prieur, Damien; Vigier, Jean-François; Wiss, Thierry; Janssen, Arne; Rothe, Jörg; Cambriani, Andrea; Somers, Joseph

    2014-04-01

    Studying self-irradiated materials is an ideal means to investigate the effect of the damage on material structure and to better understand the behavior of irradiated nuclear fuels. In this context, X-ray diffraction, X-ray absorption spectroscopy and transmission electron microscopy have been used to investigate self-irradiation damaged AmO2. Combining these techniques allows studying the microstructure and the variation of the fluorite structure at both short-range and long-range order. Thus, the increase of both interatomic distances and lattice parameter was shown, as well as the presence of nanometer sized He bubbles and dislocation loops. As confirmed by the observed high-level of crystallinity, the fluorite structure exhibits a high radiation tolerance, which is confirmed by the low increase of the lattice parameter. This could be explained by a self-annealing mechanism of the created defects at room temperature.

  17. A FLUORESCENCE BASED ASSAY FOR DNA DAMAGE: INDUCED BY RADIATION, CHEMICALS AND ENZYMES

    EPA Science Inventory

    A simple and rapid assay to detect DNA damage is reported. This assay is based on the ability of certain dyes to fluoresce upon intercalation with dsDNA. Damage caused by ultraviolet (UV) radiation, chemicals or restriction enzymes is detected using this assay. UV radiation at...

  18. Primary radiation damage of protein crystals by an intense synchrotron X-ray beam.

    PubMed

    Teng, T Y; Moffat, K

    2000-09-01

    X-ray radiation damage of a lysozyme single crystal by an intense monochromatic beam from a third-generation radiation source at the Advanced Photon Source has been studied. The results show that primary radiation damage is linearly dependent on the X-ray dose even when the crystal is at cryogenic temperatures. The existence of an upper limit for the primary radiation damage was observed. Above the threshold of approximately 1 x 10(7) Gy, excessive damage of the crystal develops which is interpreted as the onset of secondary and/or tertiary radiation damage. This upper limit of X-ray dose is compared with Henderson's limit [Henderson (1990). Proc. R. Soc. London, B241, 6-8], and its implication for the amount of useful X-ray diffraction data that can be obtained for crystals of a given scattering power is also discussed. PMID:16609214

  19. Clustered DNA damages induced in human hematopoietic cells by low doses of ionizing radiation

    NASA Technical Reports Server (NTRS)

    Sutherland, Betsy M.; Bennett, Paula V.; Cintron-Torres, Nela; Hada, Megumi; Trunk, John; Monteleone, Denise; Sutherland, John C.; Laval, Jacques; Stanislaus, Marisha; Gewirtz, Alan

    2002-01-01

    Ionizing radiation induces clusters of DNA damages--oxidized bases, abasic sites and strand breaks--on opposing strands within a few helical turns. Such damages have been postulated to be difficult to repair, as are double strand breaks (one type of cluster). We have shown that low doses of low and high linear energy transfer (LET) radiation induce such damage clusters in human cells. In human cells, DSB are about 30% of the total of complex damages, and the levels of DSBs and oxidized pyrimidine clusters are similar. The dose responses for cluster induction in cells can be described by a linear relationship, implying that even low doses of ionizing radiation can produce clustered damages. Studies are in progress to determine whether clusters can be produced by mechanisms other than ionizing radiation, as well as the levels of various cluster types formed by low and high LET radiation.

  20. Radiation damage of BGO and CsI(Tl) crystals

    NASA Astrophysics Data System (ADS)

    Bieler, Ch.; Burkart, D.; Marks, J.; Riebesell, M.; Spitzer, H.; Wittenburg, K.; Winter, G.-G.

    1985-02-01

    We have measured the response of five 10-20 cm long BGO crystals from different manufacturers to irradiation with 137Cs γ-rays at doses of 40 and 85 rad. Immediately after irradiation the pulse height drops by 26-38% and recovers only partially with time. 110 d after irradiation the remaining damage is between 1 and 13%. A 10 cm long CsI (Tl) crystal shows pulse height reductions after irradiation which do not recover with time. The cumulative effect of a continuous irradiation on a BGO crystal (1 × 1× 15 cm 3) in a partially shielded position on the beam pipe of PETRA was measured over a period of 53 d. At an average daily dose of 1.9 rad the pulse height dropped continuously resulting in an overall pulse height loss of 9% in 7 weeks. This indicates that BGO when applied in long and narrow shapes is more sensitive to small radiation doses than previously assumed.

  1. Potential vascular damage from radiation in the space environment

    NASA Astrophysics Data System (ADS)

    Griem, M. L.; Robotewskyj, A.; Nagel, R. H.

    1994-10-01

    Cultured endothelial cells of blood vessels have a Do of 2 Gy for X-rays. A dose of 0.5 Gy of X-rays has an acute effect on vessel diameter. The vessels may show other acute effects such as change in permeability including a change in the blood brain barrier. Changes occurring from late effects of chronic exposure in vascular architecture include telangiectasia and decrease in vascular density. Changes in the perivascular connective tissue particularly collagen may play a role in these changes. After charged particle exposure of 15 and 30 Gy, radiation changes in the blood brain barrier and vascular changes are noted in the nervous system. These long term changes are recorded by PET, MRI, and CT imaging. Chronic exposure to alpha particles causes vascular damage in compact bone resulting in bone infarcts. Using tandem scanning confocal microscopy in-situ imaging of the capillaries and collagen of the papillary dermis provides a non-invasive method of serial recording of changes in irradiated microvasculature.

  2. UV radiation and freshwater zooplankton: damage, protection and recovery

    PubMed Central

    Rautio, Milla; Tartarotti, Barbara

    2011-01-01

    While many laboratory and field studies show that zooplankton are negatively affected when exposed to high intensities of ultraviolet radiation (UVR), most studies also indicate that zooplankton are well adapted to cope with large variations in their UVR exposure in the pelagic zone of lakes. The response mechanisms of zooplankton are diverse and efficient and may explain the success and richness of freshwater zooplankton in optically variable waters. While no single behavioural or physiological protection mechanism seems to be superior, and while several unexplained and contradictory patterns exist in zooplankton UVR ecology, recent increases in our understanding are consistent with UVR playing an important role for zooplankton. This review examines the variability in freshwater zooplankton responses to UVR, with a focus on crustacean zooplankton (Cladocera and Copepoda). We present an overview of UVR-induced damages, and the protection and recovery mechanisms freshwater zooplankton use when exposed to UVR. We review the current knowledge of UVR impact on freshwater zooplankton at species and community levels, and discuss briefly how global change over the last three decades has influenced the UVR milieu in lakes. PMID:21516254

  3. Ultraviolet radiation effects on the infrared damage rate of a thermal control coating

    NASA Technical Reports Server (NTRS)

    Bass, J. A.

    1972-01-01

    The effects of ultraviolet radiation on the infrared reflectance of ZnO silicone white thermal coatings were investigated. Narrow band ultraviolet radiation for wavelengths in the 2200A to 3500A range by a monochromator and a high pressure, 150-W Eimac xenon lamp. The sample was irradiated while in a vacuum of at least 0.000001 torr, and infrared reflectance was measured in situ with a spectroreflectometer at 19,500A. Reflectance degradation was studied as a function of wavelength, time, intensity, and dose. Damage was wavelength dependent at constant exposure, but no maximum was evident above the shortest wavelength investigated here. The degradation rate at constant intensity was an exponential function of time and varies with intensity.

  4. Radiation damage studies for the SDC electromagnetic calorimeter

    NASA Astrophysics Data System (ADS)

    Fazely, A. R.; Gunasingha, R.; Imlay, R. L.; Khosravi, E. S.; Lim, Jit-Ning; Lyndon, C.; McMills, G.; McNeil, R. R.; Metcalf, W. J.; Courtney, J. C.; Tashakkori, R.; Vegara, B. J.

    1993-01-01

    We report the results from a year long study aimed at radiation resistance and optical performance of scintillator tile with green wave shifter fiber readout. A careful investigation of several rad-hard plastic scintillators from Bicron and Kuraray, studies indicate that for a specific rad-hard Bicron scintillator, it is possible to build a tile/fiber EM calorimeter that can operate in the design luminosity of SSC. This calorimeter with excellent optical response would only have a light loss of about 5% after being exposed to 1 Mrad.

  5. Molecular dynamics study of radiation damage and microstructure evolution of zigzag single-walled carbon nanotubes under carbon ion incidence

    NASA Astrophysics Data System (ADS)

    Li, Huan; Tang, Xiaobin; Chen, Feida; Huang, Hai; Liu, Jian; Chen, Da

    2016-07-01

    The radiation damage and microstructure evolution of different zigzag single-walled carbon nanotubes (SWCNTs) were investigated under incident carbon ion by molecular dynamics (MD) simulations. The radiation damage of SWCNTs under incident carbon ion with energy ranging from 25 eV to 1 keV at 300 K showed many differences at different incident sites, and the defect production increased to the maximum value with the increase in incident ion energy, and slightly decreased but stayed fairly stable within the majority of the energy range. The maximum damage of SWCNTs appeared when the incident ion energy reached 200 eV and the level of damage was directly proportional to incident ion fluence. The radiation damage was also studied at 100 K and 700 K and the defect production decreased distinctly with rising temperature because radiation-induced defects would anneal and recombine by saturating dangling bonds and reconstructing carbon network at the higher temperature. Furthermore, the stability of a large-diameter tube surpassed that of a thin one under the same radiation environments.

  6. An Assessment of Radiation Damage Models and Methods

    SciTech Connect

    Stoller, Roger E; Mansur, Louis K

    2005-05-01

    The current state of development of the primary models used for investigating and simulating irradiation effects in structural alloys of interest to the U.S. DOE's Generation-IV reactor program are discussed. The underlying theory that supports model development is also described where appropriate. First, the key processes that underlie radiation-induced changes in material properties are summarized, and the types of radiation effects that subsequently arise are described. Future development work needed in order for theory, modeling, and computational materials science to support and add value to the Gen IV reactor materials program are then outlined. The expected specific outcomes and overall benefits of the required effort are: the knowledge to extrapolate material behavior to conditions for which there are no experimental data; systematic understanding of mechanisms and processes to enable confident interpolation between point-by-point experimental observations; acceleration of the development, selection, and qualification of materials for reactor service; and prediction of material response to real-world operating load histories which often involve a complicated superposition of time, temperature, radiation dose rate, and mechanical loading conditions. Opportunities for international collaboration to accelerate progress in all of the required research areas are briefly discussed, particularly in the context of two well coordinated, broad-based research projects on modeling and simulation of radiation effects on materials that are currently funded in Europe. In addition to providing the opportunity for substantial leveraging of the DOE-funded activities in this area, these projects may serve as models for future development within the Gen-IV program. The larger of these two projects, which involves 12 European research laboratories and 16 universities, is called PERFECT and is funded by the European Union. A smaller effort focusing on developing predictive

  7. Stability of Radiation Induced Chromosome Damage in Human Peripheral Blood Lymphocytes

    NASA Technical Reports Server (NTRS)

    Cucinotta, F. A.; George, K.; Willingham, V.

    2006-01-01

    Chromosome damage in an individual's peripheral blood lymphocytes can be an indicator of radiation exposure and this data can be used to evaluate dose after accidental or occupational exposure. Evidence suggests that the yield of chromosome damage in lymphocytes is also a relevant biomarker of cancer risk in humans that reflects individual cancer susceptibility. It follows that biomonitoring studies can be used to uncover subjects who are particularly susceptible to radiation damage and therefore at higher risk of cancer. Translocations and other stable aberrations are commonly believed to persist in peripheral blood cells for many years after exposure, and it has been suggested that translocations can be used for assessing retrospective radiation doses or chronic exposures. However, recent investigations suggest that translocations might not always persist indefinitely. We measured chromosome aberrations in the blood lymphocytes of six astronauts before their respective missions of approximately 3 to 6 months onboard the international space station, and again at various intervals up to 5 years after flight. In samples collected a few days after return to earth, the yield of chromosome translocations had significantly increased compared with preflight values, and results indicate that biodosimetry estimates lie within the range expected from physical dosimetry. However, for five of the astronauts, follow up analysis revealed a temporal decline in translocations with half-lives ranging from 10 to 58 months. The yield of exchanges remained unchanged for the sixth astronaut during an observation period of 5 months post-flight. These results may indicate complications with the use of stable aberrations for retrospective dose reconstruction and could affect cancer risk predictions that are estimated from yields of chromosome damage obtained shortly after exposure.

  8. HSPB1 polymorphisms might be associated with radiation-induced damage risk in lung cancer patients treated with radiotherapy.

    PubMed

    Li, Xiaofeng; Xu, Sheng; Cheng, Yu; Shu, Jun

    2016-05-01

    Several studies investigating the association between heat shock protein beta-1 (HSPB1) polymorphisms and radiation-induced damage in lung cancer patients administrated with radiotherapy have derived conflicting results. This meta-analysis aimed to assess the association between the HSPB1 genes' (rs2868370 and rs2868371) polymorphisms and the risk of radiation-induced damage in lung cancer patients. After an electronic literature search, four articles including six studies were found to be eligible for this meta-analysis. No association was observed between rs2868370 genotypes and radiation-induced damage risk. However, rs2868371 showed a statistically increased risk of radiation-induced damage under CC vs. CG/GG model (OR = 1.59, 95 % CI = 1.10-2.29). Subgroup analysis by ethnicity showed that the genotypes of rs2868371 were also associated with a significantly increased risk of radiation-induced damage in CC vs. CG/GG model (OR = 1.86, 95 % CI = 1.21-2.83) among mixed ethnicities which are mainly comprised of white people. When the data was stratified by organ-damaged, a significant association was only observed in the esophagus group (OR = 2.94, 95 % CI = 1.35-6.37, for CC vs. CG/GG model). In conclusion, the present study demonstrated that the rs2868371 genotypes of HSPB1 might be associated with radiation-induced esophagus damage risk, especially in Caucasians but not in the Asian population. PMID:26874728

  9. Investigation of retinal damage during refractive eye surgery

    NASA Astrophysics Data System (ADS)

    Schumacher, S.; Sander, M.; Dopke, C.; Grone, A.; Ertmer, W.; Lubatschowski, H.

    2005-04-01

    Ultrashort laser pulses are increasingly used in refractive eye surgery to cut inside transparent corneal tissue. This is exploited by the fs-LASIK procedure which affords the opportunity to correct ametropia without any mechanical effects. The cutting process is caused by the optical breakdown occurring in the laser focus. During this process only a certain amount of the pulse energy is deposited into the tissue. The remaining pulse energy propagates further through the eye and interacts with the retina and the strong absorbing tissue layers behind. Therefore this investigation shall clarify if the intensity of the remaining laser pulse and the resulting temperature field can damage the retina and the surrounding tissue. Threshold values of the retinal tissue and theoretical calculations of the temperature field will be presented.

  10. Micro-inhomogeneity effects and radiation damage in semi-insulating GaAs radiation detectors

    SciTech Connect

    Bates, R.; O`Shea, V.; Raine, C.; Smith, K.M.; Didziulis, R.; Kazukauskas, V.; Rinkevicius, V.; Storasta, J.; Vaitkus, J.

    1998-06-01

    Thermally-stimulated current (TSC) measurements and a detailed analysis of current-voltage (I-V) characteristics have been made on semi-insulating GaAs (SI-GaAs) Schottky diode particle detectors, fabricated on substrates from several supplies, before and after irradiation with 24 GeV protons and 300 MeV pions. The analysis of I-V characteristics allows the determination of the barrier height and bulk resistance in detectors. Changes observed in I-V characteristics and TSC spectra after irradiation are described and a dislocation-net model of radiation-damaged devices is proposed.

  11. Molecular dynamics study of the bulk temperature effect on primary radiation damage in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Sabathier, C.; Wiktor, J.; Maillard, S.

    2015-06-01

    The effect of bulk temperature on the primary damage induced by a displacement cascade was investigated in uranium dioxide using classical molecular dynamics simulations. In this study, the Morelon potentials were used to model the middle-range interactions between the atoms that constitute the host matrix during the radiation events. Cascades were initiated by accelerating a uranium primary knock-on atom at 10keV inside a perfect UO2 lattice at a temperature between 700K and 1800K , a range which comprises in-pile temperatures of oxide fuels in light water reactors in standard operating conditions. Cascade overlap sequences were also simulated at 700K and 1400K in order to study the radiation damage accumulation in the oxide fuel. This study reveals the maximum damage level which the material can accommodate for decreases with the temperature. Furthermore the direct formation of vacancy clusters under irradiation is considerably slowed down above 1000K , notably during cascade overlap sequences.

  12. Radiation damage studies related to nuclear waste forms

    SciTech Connect

    Gray, W.J.; Wald, J.W.; Turcotte, R.P.

    1981-12-01

    Much of the previously reported work on alpha radiation effects on crystalline phases of importance to nuclear waste forms has been derived from radiation effects studies of composite waste forms. In the present work, two single-phase crystalline materials, Gd/sub 2/Ti/sub 2/O/sub 7/ (pyrochlore) and CaZrTi/sub 2/O/sub 7/ (zirconolite), of relative importance to current waste forms were studied independently by doping with /sup 244/Cm at the 3 wt % level. Changes in the crystalline structure measured by x-ray diffraction as a function of dose show that damage ingrowth follows an expected exponential relationship of the form ..delta..V/V/sub 0/ = A(1-exp(-BD)). In both cases, the materials became x-ray amorphous before the estimated saturation value was reached. The predicted magnitudes of the unit cell volume changes at saturation are 5.4% and 3.5%, respectively, for Gd/sub 2/Ti/sub 2/O/sub 7/ and CaZrTi/sub 2/O/sub 7/. The later material exhibited anisotropic behavior in which the expansion of the monoclinic cell in the c/sub 0/ direction was over five times that of the a/sub 0/ direction. The effects of transmutations on the properties of high-level waste solids have not been studied until now because of the long half-lives of the important fission products. This problem was circumvented in the present study by preparing materials containing natural cesium and then irradiating them with neutrons to produce /sup 134/Cs, which has only a 2y half-life. The properties monitored at about one year intervals following irradiation have been density, leach rate and microstructure. A small amount of x-ray diffraction work has also been done. Small changes in density and leach rate have been observed for some of the materials, but they were not large enough to be of any consequence for the final disposal of high level wastes.

  13. Radiation damage calculations for the APT materials test program

    SciTech Connect

    Corzine, R.K.; Wechsler, M.S.; Dudziak, D.J.; Ferguson, P.D.; James, M.R.

    1999-09-01

    A materials irradiation was performed at the Los Alamos Neutron Science Center (LANSCE) in the fall of 1996 and spring of 1997 in support of the Accelerator Production of Tritium (APT) program. Testing of the irradiated materials is underway. In the proposed APT design, materials in the target and blanket are to be exposed to protons and neutrons over a wide range of energies. The irradiation and testing program was undertaken to enlarge the very limited direct knowledge presently available of the effects of medium-energy protons ({approximately}1 GeV) on the properties of engineering materials. APT candidate materials were placed in or near the LANSCE accelerator 800-MeV, 1-mA proton beam and received roughly the same proton current density in the center of the beam as would be the case for the APT facility. As a result, the proton fluences achieved in the irradiation were expected to approach the APT prototypic full-power-year values. To predict accurately the performance of materials in APT, radiation damage parameters for the materials experiment must be determined. By modeling the experiment, calculations for atomic displacement, helium and hydrogen cross sections and for proton and neutron fluences were done for representative samples in the 17A, 18A, and 18C areas. The LAHET code system (LCS) was used to model the irradiation program, LAHET 2.82 within LCS transports protons > 1 MeV, and neutrons >20 MeV. A modified version of MCNP for use in LCS, HMCNP 4A, was employed to tally neutrons of energies <20 MeV.

  14. Recent radiation damage studies and developments of the Marlowe code

    NASA Astrophysics Data System (ADS)

    Ortiz, C. J.; Souidi, A.; Becquart, C. S.; Domain, C.; Hou, M.

    2014-07-01

    Radiation damage in materials relevant to applications evolves over time scales spanning from the femtosecond - the characteristic time for an atomic collision - to decades - the aging time expected for nuclear materials. The relevant kinetic energies of atoms span from thermal motion to the MeV range.The question motivating this contribution is to identify the relationship between elementary atomic displacements triggered by irradiation and the subsequent microstructural evolution of metals in the long term. The Marlowe code, based on the binary collision approximation (BCA) is used to simulate the sequences of atomic displacements generated by energetic primary recoils and the Object Kinetic Monte Carlo code LAKIMOCA, parameterized on a range of ab initio calculations, is used to predict the subsequent long-term evolution of point defect and clusters thereof. In agreement with full Molecular Dynamics, BCA displacement cascades in body-centered cubic (BCC) Fe and a face-centered cubic (FCC) Febond Nibond Cr alloy display recursive properties that are found useful for predictions in the long term.The case of defects evolution in W due to external irradiation with energetic H and He is also discussed. To this purpose, it was useful to extend the inelastic energy loss model available in Marlowe up to the Bethe regime. The last version of the Marlowe code (version 15) was delivered before message passing instructions softwares (such as MPI) were available but the structure of the code was designed in such a way to permit parallel executions within a distributed memory environment. This makes possible to obtain N different cascades simultaneously using N independent nodes without any communication between processors. The parallelization of the code using MPI was recently achieved by one author of this report (C.J.O.). Typically, the parallelized version of Marlowe allows simulating millions of displacement cascades using a limited number of processors (<64) within only

  15. Protection of radiation detectors from fast neutron damage

    SciTech Connect

    Kronenberg, S.

    1986-09-02

    A device is described for measuring radiation emitted from a nuclear explosion, the radiation having a comparatively fast moving gamma ray component and a comparatively slower neutron component. The device consists of: a solid state crystal radiation detector; a voltage source applied to bias the detector; and means responsive to the gamma ray component for removing the bias voltage for a predetermined time period whereby the crystal radiation detector is rendered less sensitive to the passage of the neutron radiation component.

  16. Thermal annealing of radiation damage in CMOS ICs in the temperature range -140 C to +375 C

    NASA Technical Reports Server (NTRS)

    Danchenko, V.; Fang, P. H.; Brashears, S. S.

    1982-01-01

    Annealing of radiation damage was investigated in the commercial, Z- and J-processes of the RCA CD4007A ICs in the temperature range from -140 C to +375 C. Tempering curves were analyzed for activation energies of thermal annealing, following irradiation at -140 C. It was found that at -140 C, the radiation-induced shifts in the threshold potentials were similar for all three processes. The radiation hardness of the Z- and J-process is primarily due to rapid annealing of radiation damage at room temperature. In the region -140 to 20 C, no dopant-dependent charge trapping is seen, similar to that observed at higher temperatures. In the unbiased Z-process n-channels, after 1 MeV electron irradiation, considerable negative charge remains in the gate oxide.

  17. Modification of radiation damage in rat spinal cord by mitotane

    SciTech Connect

    Glicksman, A.S.; Bliven, S.F.; Leith, J.T.

    1982-07-01

    Modification of the paralytic response in rats after 6-MV photon irradiation of the spinal cord with either single or split exposures (two equal fractions given in a 24-hour period) by mitotane was investigated. Mitotane was administered as a suspension in physiologic saline (300 mg/kg/day) for either 5 days prior to or 5 days after irradiation. For rats receiving split doses of 6-MV photons, either the last two doses of mitotane were given 2 hours prior to each radiation fraction or mitotane was begun 2 hours after the second fraction and continued for 5 days. The data to 6 months after irradiation indicate that, in rats given mitotane for 5 days prior to single-dose photon irradiation, the paralytic response (as defined by the dose needed to produce paralysis in 50% of the irradiated groups of rats) was enhanced by a dose-enhancement factor (DEF) of 1.40. The DEF in the group of rats given mitotane after single doses of 6-MV photons was 1.15. In the split-dose irradiation experiments, the DEF for the groups of rats given mitotane prior to each radiation fraction was 1.36; while the DEF for the group of rats receiving mitotane beginning after the second fraction was 1.18. These data indicate that mitotane can potentiate the effects of 6-MV photon irradiation to the central nervous system, with mitotane administered prior to irradiation being the most effective sequence.

  18. Postbuckling Investigations of Piezoelectric Microdevices Considering Damage Effects

    PubMed Central

    Sun, Zhigang; Wang, Xianqiao

    2014-01-01

    Piezoelectric material has been emerging as a popular building block in MEMS devices owing to its unique mechanical and electrical material properties. However, the reliability of MEMS devices under buckling deformation environments remains elusive and needs to be further explored. Based on the Talreja's tensor valued internal state damage variables as well as the Helmhotlz free energy of piezoelectric material, a constitutive model of piezoelectric materials with damage is presented. The Kachanvo damage evolution law under in-plane compressive loads is employed. The model is applied to the specific case of the postbuckling analysis of the piezoelectric plate with damage. Then, adopting von Karman's plate theory, the nonlinear governing equations of the piezoelectric plates with initial geometric deflection including damage effects under in-plane compressive loads are established. By using the finite difference method and the Newmark scheme, the damage evolution for damage accumulation is developed and the finite difference procedure for postbuckling equilibrium path is simultaneously employed. Numerical results show the postbuckling behaviors of initial flat and deflected piezoelectric plates with damage or no damage under different sets of electrical loading conditions. The effects of applied voltage, aspect ratio of plate, thick-span ratio of plate, damage as well as initial geometric deflections on the postbuckling behaviors of the piezoelectric plate are discussed. PMID:24618774

  19. Infrared A radiation promotes survival of human melanocytes carrying ultraviolet radiation-induced DNA damage.

    PubMed

    Kimeswenger, Susanne; Schwarz, Agatha; Födinger, Dagmar; Müller, Susanne; Pehamberger, Hubert; Schwarz, Thomas; Jantschitsch, Christian

    2016-06-01

    The link between solar radiation and melanoma is still elusive. Although infrared radiation (IR) accounts for over 50% of terrestrial solar energy, its influence on human skin is not well explored. There is increasing evidence that IR influences the expression patterns of several molecules independently of heat. A previous in vivo study revealed that pretreatment with IR might promote the development of UVR-induced non-epithelial skin cancer and possibly of melanoma in mice. To expand on this, the aim of the present study was to evaluate the impact of IR on UVR-induced apoptosis and DNA repair in normal human epidermal melanocytes. The balance between these two effects is a key factor of malignant transformation. Human melanocytes were exposed to physiologic doses of IR and UVR. Compared to cells irradiated with UVR only, simultaneous exposure to IR significantly reduced the apoptotic rate. However, IR did not influence the repair of UVR-induced DNA damage. IR partly reversed the pro-apoptotic effects of UVR via modification of the expression and activity of proteins mainly of the extrinsic apoptotic pathway. In conclusion, IR enhances the survival of melanocytes carrying UVR-induced DNA damage and thereby might contribute to melanomagenesis. PMID:26844814

  20. Investigation and application of neutron damage to bipolar transistors in light water reactor dosimetry

    SciTech Connect

    Roknizadeh, M.

    1987-01-01

    A method of fast neutron metrology and a basis for prediction of changes in performance parameters of semiconductor devices in power plant radiation environments has been established using Cf-252 sources. Three general purpose NPN bipolar transistors (PN2222A, ECG-196, and ECG-184) were chosen as the neutron damage monitors and the change in inverse d.c. current gain before and after irradiation was chosen as the damage parameter for the measurement. The main findings of the investigation were as follows: the change in inverse d.c. current gain for PN2222A transistors was approximately a linear function of the neutron fluence up to 2.0E15 n(1MeV)/cm/sup 2/. The concept of 1-MeV equivalent neutron fluence which characterizes an incident energy-fluence spectrum in terms of the fluence of monoenergetic neutrons at 1 MeV, is in error for application to common transistors in a typical power plant environment. Finally, the normalized damage coefficient which is the ratio of damage to 1-MeV equivalent neutron fluence divided by the measured base transit time of individual transistors, for all three types of transistors is nearly the same with an average value of 1.27E - 7 +/- 15.0% cm/sup 2//m(1 MeV).Sec.

  1. Radiation damage study using small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Rétfalvi, E.; Török, Gy; Rosta, L.

    2000-03-01

    Nuclear radiation provides important changes in the microstructure of metallic components of nuclear power plant and research reactors, influencing their mechanical properties. The investigation of this problem has primary interest for the safety and life-time of such nuclear installations. For the characterization of this kind of nanostructures small angle neutron scattering technique is a very useful tool. We have carried out experiments on samples of irradiated reactor vessel material and welded components of VVER-440-type reactors on the SANS instrument at the Budapest Research Reactor. In our measurements irradiated as well as non-irradiated samples were compared and magnetic field was applied for viewing the magnetic structure effects of the materials. A clear modification of the structure due to irradiation was obtained. Our data were analyzed by the ITP92 code, the inverse Fourier transform program of O. Glatter [1].

  2. Investigation of Sideband Index Response to Prototype Gear Tooth Damage

    NASA Technical Reports Server (NTRS)

    Dempsey, Paula J.

    2013-01-01

    The objective of this analysis was to evaluate the ability of gear condition indicators (CI) to detect contact fatigue damage on spiral bevel gear teeth. Tests were performed in the NASA Glenn Spiral Bevel Gear Fatigue Rig on eight prototype gear sets (pinion/gear). Damage was initiated and progressed on the gear and pinion teeth. Vibration data was measured during damage progression at varying torque values while varying damage modes to the gear teeth were observed and documented with inspection photos. Sideband indexes (SI) and root mean square (RMS) CIs were calculated from the time synchronous averaged vibration data. Results found that both CIs respond differently to varying torque levels, damage levels and damage modes

  3. Radiation-Induced Liver Damage: Correlation of Histopathology with Hepatobiliary Magnetic Resonance Imaging, a Feasibility Study

    SciTech Connect

    Seidensticker, Max; Burak, Miroslaw; Kalinski, Thomas; Garlipp, Benjamin; Koelble, Konrad; Wust, Peter; Antweiler, Kai; Seidensticker, Ricarda; Mohnike, Konrad; Pech, Maciej; Ricke, Jens

    2015-02-15

    PurposeRadiotherapy of liver malignancies shows promising results (radioembolization, stereotactic irradiation, interstitial brachytherapy). Regardless of the route of application, a certain amount of nontumorous liver parenchyma will be collaterally damaged by radiation. The functional reserve may be significantly reduced with an impact on further treatment planning. Monitoring of radiation-induced liver damage by imaging is neither established nor validated. We performed an analysis to correlate the histopathological presence of radiation-induced liver damage with functional magnetic resonance imaging (MRI) utilizing hepatobiliary contrast media (Gd-BOPTA).MethodsPatients undergoing local high-dose-rate brachytherapy for whom a follow-up hepatobiliary MRI within 120 days after radiotherapy as well as an evaluable liver biopsy from radiation-exposed liver tissue within 7 days before MRI were retrospectively identified. Planning computed tomography (CT)/dosimetry was merged to the CT-documentation of the liver biopsy and to the MRI. Presence/absence of radiation-induced liver damage (histopathology) and Gd-BOPTA uptake (MRI) as well as the dose applied during brachytherapy at the site of tissue sampling was determined.ResultsFourteen biopsies from eight patients were evaluated. In all cases with histopathological evidence of radiation-induced liver damage (n = 11), no uptake of Gd-BOPTA was seen. In the remaining three, cases no radiation-induced liver damage but Gd-BOPTA uptake was seen. Presence of radiation-induced liver damage and absence of Gd-BOPTA uptake was correlated with a former high-dose exposition.ConclusionsAbsence of hepatobiliary MRI contrast media uptake in radiation-exposed liver parenchyma may indicate radiation-induced liver damage. Confirmatory studies are warranted.

  4. Radiation damage in protein serial femtosecond crystallography using an x-ray free-electron laser

    PubMed Central

    Lomb, Lukas; Barends, Thomas R. M.; Kassemeyer, Stephan; Aquila, Andrew; Epp, Sascha W.; Erk, Benjamin; Foucar, Lutz; Hartmann, Robert; Rudek, Benedikt; Rolles, Daniel; Rudenko, Artem; Shoeman, Robert L.; Andreasson, Jakob; Bajt, Sasa; Barthelmess, Miriam; Barty, Anton; Bogan, Michael J.; Bostedt, Christoph; Bozek, John D.; Caleman, Carl; Coffee, Ryan; Coppola, Nicola; DePonte, Daniel P.; Doak, R. Bruce; Ekeberg, Tomas; Fleckenstein, Holger; Fromme, Petra; Gebhardt, Maike; Graafsma, Heinz; Gumprecht, Lars; Hampton, Christina Y.; Hartmann, Andreas; Hauser, Günter; Hirsemann, Helmut; Holl, Peter; Holton, James M.; Hunter, Mark S.; Kabsch, Wolfgang; Kimmel, Nils; Kirian, Richard A.; Liang, Mengning; Maia, Filipe R. N. C.; Meinhart, Anton; Marchesini, Stefano; Martin, Andrew V.; Nass, Karol; Reich, Christian; Schulz, Joachim; Seibert, M. Marvin; Sierra, Raymond; Soltau, Heike; Spence, John C. H.; Steinbrener, Jan; Stellato, Francesco; Stern, Stephan; Timneanu, Nicusor; Wang, Xiaoyu; Weidenspointner, Georg; Weierstall, Uwe; White, Thomas A.; Wunderer, Cornelia; Chapman, Henry N.; Ullrich, Joachim; Strüder, Lothar; Schlichting, Ilme

    2013-01-01

    X-ray free-electron lasers deliver intense femtosecond pulses that promise to yield high resolution diffraction data of nanocrystals before the destruction of the sample by radiation damage. Diffraction intensities of lysozyme nanocrystals collected at the Linac Coherent Light Source using 2 keV photons were used for structure determination by molecular replacement and analyzed for radiation damage as a function of pulse length and fluence. Signatures of radiation damage are observed for pulses as short as 70 fs. Parametric scaling used in conventional crystallography does not account for the observed effects. PMID:24089594

  5. Exploiting radiation damage control on apatite (U Th)/He dates in cratonic regions

    NASA Astrophysics Data System (ADS)

    Flowers, Rebecca M.

    2009-01-01

    Apatites from four pairs of samples of Precambrian basement from the western Canadian shield were analyzed by (U-Th)/He thermochronometry to test for the influence of radiation damage on apatite (U-Th)/He dates in this cratonic region. Recent studies have demonstrated that the accumulation of radiation damage increases the apatite He retentivity, so that apatites with a span of effective U concentrations, eU, that experienced the same thermal history may be characterized by a range of closure temperatures. In this investigation, each sample pair consisted of a mafic dike cross-cutting felsic gneisses from a single outcrop or nearby outcrops that contained apatites with a span of eU. The apatites yielded (U-Th)/He dates from 846 to 123 Ma, and were positively correlated with eU within each sample pair. These results can be explained using a model that tracks the evolution of He mobility in response to the accumulation of radiation damage. When coupled with regional geological constraints, the data appear to require partial to complete He loss due to burial and reheating in Phanerozoic time. New apatite fission- track dates and length data were obtained for five of these samples. The apatite fission- track dates are Proterozoic regardless of apatite eU. Thermal history simulations indicate that the apatite fission-track data are compatible with the (U-Th)/He results, although the thermal histories are not identical in detail and the fission-track results alone do not require Phanerozoic heating. Together the data are consistent with burial of this region by ≥ 1 km of Phanerozoic strata that were subsequently denuded, thus pointing toward significant Phanerozoic deposition in the North American cratonic interior hundreds of kilometers east of where previously documented. The results suggest that exploiting radiation damage control on apatite (U-Th)/He dates through investigation of surface sample apatites with a span of closure temperatures can impose tighter

  6. Radiation-induced renal damage: the effects of hyperfractionation. [Mice

    SciTech Connect

    Stewart, F.A.; Soranson, J.A.; Alpen, E.L.; Williams, M.V.; Denekamp, J.

    1984-05-01

    The response of mouse kidneys to multifraction irradiation was assessed using three nondestructive functional end points. A series of schedules was investigated giving 1, 2, 4, 8, 16, 32, or 64 equal X-ray doses, using doses per fraction in the range of 0.9 to 16 Gy. The overall treatment time was kept constant at 3 weeks. Kidney function was assessed from 19 to 48 weeks after irradiation by measuring changes in isotope clearance, urine output, and hematocrit. All three assays yielded steep dose-effect curves from which the repair capacity of kidney could be estimated by comparing the isoeffective doses in different schedules. There was a marked influence of fractionation, with increasing dose being required to achieve the same level of damage for increasing fraction number, even between 32 and 64 fractions. The data are well fitted by a linear quadratic dose-response equation, and analysis of the data would suggest that hyperfractionation, using extremely small X-ray doses per fraction, would spare kidneys relative to tumors and acutely responding tissues.

  7. Radiation damage in protein crystals is reduced with a micron-sized X-ray beam

    PubMed Central

    Sanishvili, Ruslan; Yoder, Derek W.; Pothineni, Sudhir Babu; Rosenbaum, Gerd; Xu, Shenglan; Vogt, Stefan; Stepanov, Sergey; Makarov, Oleg A.; Corcoran, Stephen; Benn, Richard; Nagarajan, Venugopalan; Smith, Janet L.; Fischetti, Robert F.

    2011-01-01

    Radiation damage is a major limitation in crystallography of biological macromolecules, even for cryocooled samples, and is particularly acute in microdiffraction. For the X-ray energies most commonly used for protein crystallography at synchrotron sources, photoelectrons are the predominant source of radiation damage. If the beam size is small relative to the photoelectron path length, then the photoelectron may escape the beam footprint, resulting in less damage in the illuminated volume. Thus, it may be possible to exploit this phenomenon to reduce radiation-induced damage during data measurement for techniques such as diffraction, spectroscopy, and imaging that use X-rays to probe both crystalline and noncrystalline biological samples. In a systematic and direct experimental demonstration of reduced radiation damage in protein crystals with small beams, damage was measured as a function of micron-sized X-ray beams of decreasing dimensions. The damage rate normalized for dose was reduced by a factor of three from the largest (15.6 μm) to the smallest (0.84 μm) X-ray beam used. Radiation-induced damage to protein crystals was also mapped parallel and perpendicular to the polarization direction of an incident 1-μm X-ray beam. Damage was greatest at the beam center and decreased monotonically to zero at a distance of about 4 μm, establishing the range of photoelectrons. The observed damage is less anisotropic than photoelectron emission probability, consistent with photoelectron trajectory simulations. These experimental results provide the basis for data collection protocols to mitigate with micron-sized X-ray beams the effects of radiation damage. PMID:21444772

  8. Study on the bias-dependent effects of proton-induced damage in CdZnTe radiation detectors using ion beam induced charge microscopy.

    PubMed

    Gu, Yaxu; Jie, Wanqi; Rong, Caicai; Xu, Lingyan; Xu, Yadong; Lv, Haoyan; Shen, Hao; Du, Guanghua; Guo, Na; Guo, Rongrong; Zha, Gangqiang; Wang, Tao; Xi, Shouzhi

    2016-09-01

    The influence of damage induced by 2MeV protons on CdZnTe radiation detectors is investigated using ion beam induced charge (IBIC) microscopy. Charge collection efficiency (CCE) in irradiated region is found to be degraded above a fluence of 3.3×10(11)p/cm(2) and the energy spectrum is severely deteriorated with increasing fluence. Moreover, CCE maps obtained under the applied biases from 50V to 400V suggests that local radiation damage results in significant degradation of CCE uniformity, especially under low bias, i. e., 50V and 100V. The CCE nonuniformity induced by local radiation damage, however, can be greatly improved by increasing the detector applied bias. This bias-dependent effect of 2MeV proton-induced radiation damage in CdZnTe detectors is attributed to the interaction of electron cloud and radiation-induced displacement defects. PMID:27399802

  9. In vitro investigation of skin damage due to microscale shearing.

    PubMed

    Jee, Taekwon; Komvopoulos, Kyriakos

    2014-11-01

    Despite several studies dealing with the mechanical and tribological properties of skin, the majority of these investigations have been performed at macroscopic levels. However, because of the multilayer structure of skin, it is necessary to perform studies at microscopic scales to reveal the effect of individual layer constituents on the overall skin response to mechanical stimuli. To bridge the gap in knowledge of the micromechanical behavior of skin, a custom-made mechanical tester, optical microscopy, and cross-sectional histology were used to examine the deformation and tribological behavior of porcine skin subjected to various normal and shear loadings. Representative friction and wear results of skin tested under unidirectional and reciprocating (cyclic) shearing (scratching) conditions are interpreted in terms of the scratching speed, normal load, and number of scratch cycles to illustrate the effects of stratum corneum, cellular epidermis, and dermis on the friction and wear characteristics of skin. Depending on the normal load and scratch time (cycles), different friction mechanisms (i.e., adhesion, plowing, and squeeze-film lubrication) and wear mechanisms (i.e., surface plasticity/plowing, bulk shearing, cohesive failure, tearing, and delamination) were found to control shear-induced skin damage. The results of this study provide insight into microscale friction and wear processes influencing the mechanical response of skin subjected to normal and shear surface tractions. PMID:24323557

  10. The effect of interferon gamma on conventional fractionated radiation-induced damage and fibrosis in the pelvic tissue of rabbits

    PubMed Central

    Yang, Yunyi; Liu, Zi; Wang, Juan; Chai, Yanlan; Su, Jin; Shi, Fan; Wang, Jiquan; Che, Shao Min

    2016-01-01

    We aim to investigate the effect of interferon gamma (IFN-γ) on conventional fractionated radiation–induced damage and fibrosis in ureter and colorectal mucosa. Fifty-two rabbits were randomly divided into three groups comprising a conventional radiation group, an IFN-γ group, and a control group. X-rays were used to irradiate the pelvic tissues of the rabbits in the IFN-γ and conventional radiation groups. Five days after radiation exposure, the rabbits in the IFN-γ group were administered 250,000 U/kg IFN-γ intramuscularly once a week for 5 weeks. The rabbits in the conventional radiation group received 5.0 mL/kg saline. The rabbits were sacrificed at 4, 8, 12, and 16 weeks postradiation, and the rectal and ureteral tissues within the radiation areas were collected. The results showed that the morphology of rectal and ureteral tissues was changed by X-ray radiation. The degree of damage at 4, 8, and 12 weeks, but not at 16 weeks, postradiation was significantly different between the IFN-γ and conventional radiation groups. The expression of transforming growth factor beta 1 mRNA in the ureter and colorectal mucosa of the IFN-γ group was significantly lower than that in the conventional radiation group at 4, 8, 12, and 16 weeks postradiation, but it was still higher than that in the control group. There were significant differences in the expression of collagen III among the three groups. IFN-γ can inhibit the radiation-induced upregulation of transforming growth factor beta 1 mRNA and collagen III protein in the ureter and colorectal mucosa and attenuate radiation-induced damage and fibrosis. PMID:27274263