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Radiation-Induced Amorphization of Crystalline Ice  

NASA Astrophysics Data System (ADS)

Crystalline ice has been unambiguously identified on the surface of most of the Jovian, Saturnian and Uranian satellites, and on the surface of some trans-Neptunian objects such as Quaoar, and 2003 EL61. This result is surprising, as the low surface temperatures of these objects should cause the ice condensed on them to be amorphous. Moreover, the surface of these bodies is constantly exposed to UV photons, solar wind, cosmic rays or energetic charged particles trapped by the planetary magnetic fields, which are known to amorphize crystalline ice. Here, we review 30 years of experimental studies of radiation-induced amorphization of crystalline ice analyzing the differences found between light and heavy ions, electrons and photons. We also present high quality near-infrared absorption spectra for amorphous and crystalline ice before and after we irradiated them with 225 keV protons. After irradiation at 80 K, the crystalline ice spectrum is altered so that it is indistinguishable from the spectrum of amorphous ice, indicating that irradiation can fully amorphize crystalline ice. We will compare these results with previous studies and discuss the astrophysical implication for planetary bodies.

Fama, Marcelo A.; Loeffler, M. J.; Raut, U.; Baragiola, R. A.



Radiation-induced amorphization of crystalline ice  

NASA Astrophysics Data System (ADS)

We study radiation-induced amorphization of crystalline ice, analyzing the results of three decades of experiments with a variety of projectiles, irradiation energy, and ice temperature, finding a similar trend of increasing resistance of amorphization with temperature and inconsistencies in results from different laboratories. We discuss the temperature dependence of amorphization in terms of the 'thermal spike' model. We then discuss the common use of the 1.65 ?m infrared absorption band of water as a measure of degree of crystallinity, an increasingly common procedure to analyze remote sensing data of astronomical icy bodies. The discussion is based on new, high quality near-infrared reflectance absorption spectra measured between 1.4 and 2.2 ?m for amorphous and crystalline ices irradiated with 225 keV protons at 80 K. We found that, after irradiation with 10 15 protons cm -2, crystalline ice films thinner than the ion range become fully amorphous, and that the infrared absorption spectra show no significant changes upon further irradiation. The complete amorphization suggests that crystalline ice observed in the outer Solar System, including trans-neptunian objects, may results from heat from internal sources or from the impact of icy meteorites or comets.

Famá, M.; Loeffler, M. J.; Raut, U.; Baragiola, R. A.



Radiation induced collapse of the crystalline structure  

NASA Astrophysics Data System (ADS)

A theory of irradiation-induced amorphization of ordered intermetallic compounds, based on the destabilization of the crystalline structure by excess defect accumulation, has been developed recently. The theory is reviewed starting with its phenomenological basis, where the microstructural evolution of intermetallic compounds that are turned amorphous by irradiation is emphasized. Next, the analysis of defect buildup that suggests the formation of a stable complex defect consisting of a vacancy-interstitial pair, called a complex, is reviewed. The possibility of a radiation induced microstructure such as interstitial clusters, in addition to complexes, in intermetallics that undergo the crystalline-to-amorphous transition is incorporated into the theory. A comparison of radiation effects in NiTi and in Zr3Al is made using a rate theory approach. In the case of the aluminide, it is found that cluster development can hinder the amorphous transition when the material is irradiated with electrons. On the other hand, enhancement of complex production in the collision cascade, explains the occurrence of the transition during ion combardment.

Pedraza, D. F.



Radiation-Induced Amorphization of Crystalline Ice  

Microsoft Academic Search

Crystalline ice has been unambiguously identified on the surface of most of the Jovian, Saturnian and Uranian satellites, and on the surface of some trans-Neptunian objects such as Quaoar, and 2003 EL61. This result is surprising, as the low surface temperatures of these objects should cause the ice condensed on them to be amorphous. Moreover, the surface of these bodies

Marcelo A. Fama; M. J. Loeffler; U. Raut; R. A. Baragiola



Preparation of inorganic crystalline compounds induced by ionizing, UV and laser radiations  

NASA Astrophysics Data System (ADS)

Results on preparation of nickel, zinc, yttrium, aluminum and cobalt oxides, zinc peroxide and hydroxide, yttrium and lutetium aluminum garnets and cobalt(II) aluminate via irradiation of aqueous solutions containing soluble metal salts and radical scavengers (formate anion or propan-2-ol) are summarized in this paper. Various physico-chemical and structural properties of prepared compounds (e.g. crystallinity, specific surface area, particle size) are also reported.All used variants of radiation method are rather convenient and simple, and yield nano-scale powder materials with interesting characteristics. Prepared materials generally have high chemical purity, high specific surface area and narrow distribution of particle size (ranging in tens of nm).Generally, accelerated electrons, gamma, and UV radiation yield materials with comparable properties and structural characteristics, but UV-radiation seems to be the most convenient for preparation of intricate compounds such as synthetic garnets and spinels, while ionizing radiation is better for preparation of compounds doped with foreign ions.Among discussed compounds, only zinc oxide, peroxide and hydroxide were prepared directly via irradiation. For preparation of other crystalline oxidic compounds, mild heat treatment of amorphous or weakly crystalline solid phase was necessary.

?uba, Václav; Pavelková, Tereza; Bárta, Jan; Gbur, Tomáš; Vlk, Martin; Zavadilová, Alena; Indrei, Jakub; Do?ekalová, Zuzana; Pospíšil, Milan; Mú?ka, Viliam



Radiation-induced crystalline-to-amorphous transition in intermetallic compounds of the Cu-Ti alloy system  

SciTech Connect

Recent progress in molecular-dynamics studies of radiation-induced crystalline-to-amorphous transition in the ordered intermetallic compounds of the Cu-Ti system is discussed. The effect of irradiation was simulated by the generation of Frenkel pairs,which resulted in both the formation of stable point defects and chemical disorder upon defect recombination. The thermodynamic, structural and mechanical responses of the compounds during irradiation were determined by monitoring changes in the system potential energy, volume expansion, pair correlation function, diffraction patterns, and elastic constants. It was found that the intermetallics Cu{sub 4}Ti{sub 3}, CuTi, and CuTi{sub 2} could be rendered amorphous by the creation of Frenkel pairs, but Cu{sub 4}Ti could not, consistent with experimental observations during electron irradiation. However, the simulations showed that Cu{sub 4}Ti did become amorphous when clusters of Frenkel pairs were introduced, indicating that this compound may be susceptible to amorphization by heavy-ion bombardment. A generalization of the Lindemann criterion was used to develop a thermodynamic description of solid-state amorphization as a disorder- induced melting process.

Lam, N.Q.; Okamoto, P.R.; Devanathan, R. (Argonne National Lab., IL (United States)); Sabochick, M.J. (Gulf States Utilities Co., Beaumont, TX (United States). Computer Applications Div.)



The radiation-induced crystalline-to-amorphous transition in zircon  

SciTech Connect

A comprehensive understanding of radiation effects in zircon, ZrSiO[sub 4], over a broad range of time scales (0.5 h to 570 million years) has been obtained by a study of natural zircon, Pu-doped zircon, and ion-beam irradiated zircon. Radiation damage in zircon results in the simultaneous accumulation of both point defects and amorphous regions. The amorphization process is consistent with models based on the multiple overlap of particle tracks, suggesting that amorphization occurs as a result of a critical defect concentration. The amorphization dose increases with temperature in two stages (below 300 K and above 473 K) and is nearly independent of the damage source ([alpha]-decay events or heavy-ion beams) at 300 K. Recrystallization of completely amorphous zircon occurs above 1300 K and is a two-step process that involves the initial formation of pseudo-cubic ZrO[sub 2].

Weber, W.J. (Materials Sciences Department, Pacific Northwest Laboratory, P.O. Box 999, Richland, Washington 99352 (United States)); Ewing, R.C.; Wang, L. (Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, New Mexico 87131 (United States))



[Radiation protectants of the crystalline lens].  


During more than a half of century, numerous compounds have been tested in different models against radiation-induced cataract. In this report, we will review the radioprotectors that have been already tested for non-human crystalline lens protection. We will focus on the most important published studies in this topic and the mechanisms of cytoprotection reported in vitro and in vivo from animals. The most frequent mechanisms incriminated in the cytoprotective effect are: free radical scavenging, limitation of lipid peroxidation, modulation of cycle progression increase of intracellular reduced glutathion pool, reduction of DNA strand breaks and limitation of apoptotic cell death. Amifostine (or Ethyol) and anethole dithiolethione (or Sulfarlem), already used clinically as chemo- and radioprotectants, could be further tested for ocular radioprotection particularly for radiation-induced cataract. PMID:15124544

Belkacémi, Y; Pasquier, D; Castelain, B; Warnet, J M; Lartigau, E



A high pulse repetition frequency ultrasound system for the ex vivo measurement of mechanical properties of crystalline lenses with laser-induced microbubbles interrogated by acoustic radiation force  

NASA Astrophysics Data System (ADS)

A high pulse repetition frequency ultrasound system for an ex vivo measurement of mechanical properties of an animal crystalline lens was developed and validated. We measured the bulk displacement of laser-induced microbubbles created at different positions within the lens using nanosecond laser pulses. An impulsive acoustic radiation force was applied to the microbubble, and spatio-temporal measurements of the microbubble displacement were assessed using a custom-made high pulse repetition frequency ultrasound system consisting of two 25 MHz focused ultrasound transducers. One of these transducers was used to emit a train of ultrasound pulses and another transducer was used to receive the ultrasound echoes reflected from the microbubble. The developed system was operating at 1 MHz pulse repetition frequency. Based on the measured motion of the microbubble, Young’s moduli of surrounding tissue were reconstructed and the values were compared with those measured using the indentation test. Measured values of Young’s moduli of four bovine lenses ranged from 2.6 ± 0.1 to 26 ± 1.4 kPa, and there was good agreement between the two methods. Therefore, our studies, utilizing the high pulse repetition frequency ultrasound system, suggest that the developed approach can be used to assess the mechanical properties of ex vivo crystalline lenses. Furthermore, the potential of the presented approach for in vivo measurements is discussed.

Yoon, Sangpil; Aglyamov, Salavat; Karpiouk, Andrei; Emelianov, Stanislav



Radiation Effects in Crystalline High-Level Nuclear Waste Solids.  

National Technical Information Service (NTIS)

Glass, cement, and crystalline-ceramic waste forms are being considered as potential solid forms for incorporation of nuclear wastes. The solidified waste will be subjected to high doses of many different radiations which may measurably alter physical pro...

W. J. Weber J. W. Wald W. J. Gray



Radiation and thermal effects on zeolites, smectites and crystalline silicotitanates  

NASA Astrophysics Data System (ADS)

Long-term radiation and thermal effects on materials in the near-field of a nuclear waste repository have been evaluated using accelerated laboratory experiments by energetic electron or ion beam irradiations. The materials studied include: zeolites, smectites, and crystalline silicotitanates (CST). In situ transmission electron microscopy (TEM) during irradiation by 200 keV electrons has shown that all of the studied materials are susceptible to radiation-induced amorphization. At room temperature, complete amorphization was observed after ionizing doses of 1010˜10 12 Gy or displacement doses of ˜0.1 dpa. The critical amorphization dose increased with temperature for CST. A peak amorphization dose was found at ˜400°C for the smectites. A new experimental approach was developed using a combination of proton irradiation, TEM, and electron microprobe analysis techniques to overcome the difficulties in studying the chemical properties in the radiation-damaged region. A clear correlation between the structural damage and changes in ion-exchange and desorption capacities has been established for zeolite-Y, which maybe useful for predicting the long-term behavior of the near-field materials in a nuclear waste repository. Radiation-induced decrease in the release rate of radionuclides has been observed for the first time in the damaged materials, indicating that the structural damage in near-field materials may be beneficial for retarding the release of radionuclides from geologic disposal repository into biosphere. Possible mechanisms for radiation-induced changes in structure, ion exchange and desorption capacities have been proposed.

Gu, Binxi


The influence of crystallinity on radiation stability of UHMWPE  

NASA Astrophysics Data System (ADS)

The influence of ionizing radiation on ultra high molecular weight polyethylene (UHMWPE) was studied using EPR spectroscopy and GC. Two samples of various degree of crystallinity, 85% and 53%, were investigated upon exposure to electron beam. In this study it was found that radicals generated following irradiation decay much faster in amorphous than in crystalline phase. The primary product generated in both phases is second ordered alkyl radical. EPR spectra detected for the sample containing 85% crystalline regions revealed a quintet of hyperfine splitting about 2.28 mT and the signal was tentatively assigned to the product of ?-fragmentation. The radiation yield of hydrogen for two studied samples of various crystallinity was similar.

Kornacka, Ewa Maria; Przybytniak, Gra?yna; ?wi?szkowski, Wojciech



Locating microearthquakes induced by hydraulic fracturing in crystalline rock  

Microsoft Academic Search

Microearthquakes induced by hydraulic fracturing in crystalline rock at a depth of 3.5 km were located with a precision of better than 30 m to obtain information about the geometry and dimensions of the fracture system produced. The induced microseismicity was monitored by a network of five vorehole seismic stations; a total of about 800 induced events were reliably located

Leigh House



Radiation effects in crystalline high-level nuclear waste solids  

NASA Astrophysics Data System (ADS)

Glass, cement, and crystalline-ceramic waste forms are being considered as potential solid forms for incorporation of nuclear wastes. The general radiation damage problem is defined and experimental results from studies of the effects of alpha decay, alpha bombardment, and transmutations on crystalline waste forms, related single-phase compounds and some glass waste forms are summarized. The results lead to the following conclusions: both alpha-recoil damage in actinide host phases and alpha damage to all other phases must be considered since significant structural changes may occur from either source; the ingrowth of damage follows exponential behavior for both alpha-recoil damage and alpha damage, leading to saturation effects in most materials; and preliminary results show no significant effect of transmutations on waste form stability.

Weber, W. J.; Wald, J. W.; Gray, W. J.



Recombination and radiation damage in crystalline silicon solar cell material  

NASA Astrophysics Data System (ADS)

This article reviews the carrier recombination mechanisms which degrade crystalline solar cells as a result of exposure to light (photo-degradation) and in the case of satellite cells after exposure to energetic electrons in space. The role of impurities is considered and in particular contamination with iron and the formation of metastable boron-oxygen complexes. The application of high resolution (Laplace) deep level transient spectroscopy in the structural identification of the induced defects is discussed with a view to controlling their formation by defect engineering.

Peaker, A. R.; Markevich, V. P.; Dobaczewski, L.



Boson induced nuclear fusion in crystalline solids  

NASA Astrophysics Data System (ADS)

In a calculation of demonstrative type collective, laser-like behavior of low energy nuclear fusion reaction of deuterons in crystalline environment is investigated. It is found that the reported extra 4He production can be appropriately described with a model well known in quantum electronics in which the quantized boson (4He) field interacts with an ensemble of two-level systems in a crystal resonator. The estimated life times of the two levels indicate that population inversion may be achieved. Thresholds of the deuteron number of the sample and of the electric current density of the pumping electrolysis are estimated in the calculation by analyzing the gain parameter and some other characteristics of the process. An explanation for the experimentally observed threshold behavior of the electric current density is given. A loss of a special type, that is the degenerate parametric amplifier mechanism, is suggested to be responsible for the difference between the expected and observed energies of the outgoing charged particles.

Kálmán, P.; Keszthelyi, T.; Kis, D.



Coherent X-ray radiation produced by microbunched beams in amorphous and crystalline radiators  

NASA Astrophysics Data System (ADS)

A review on the coherent X-ray bremsstrahlung (CXBR), X-ray transition (CXTR), resonance transition (CXRTR), diffraction (CXDR), crystalline undulator (CXCUR), undulator (CXUR), channeling (CXChR) and parametric X-ray (CXPXR) radiations produced by microbunched beams passing through crystalline radiators without the accompanying SASE beams of X-ray FELs is given. Formulas for the spectral and angular distributions as well as for the total number of photons of these radiations are derived and numerically studied. It is discussed the possibility of observing of these radiations as well as their application for the study of the parameters of the electron beam microbunching which is important for the effectiveness of XFELs and for production of additional beams of intense monochromatic X-ray beams.

Ispirian, K. A.



Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.  

SciTech Connect

Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S. (Materials Science Division); (Brown Univ.); (Chinese Academy of Sciences)



Radiation-induced proctosigmoiditis  

Microsoft Academic Search

In a prospective study, 37 consecutive patients with radiation-induced proctosigmoiditis were randomized to receive a four-week course of either 3.0 g oral sulfasalazine plus 20 mg twice daily rectal prednisolone enemas (group I,N=18) or 2.0 g twice daily rectal sucralfate enemas plus oral placebo (group II,N=19). The two groups were comparable with respect to demographic features, duration of symptoms, and

R. Kochhar; F. Patel; S. C. Sharma; S. Ayyagari; R. Aggarwal; M. K. Goenka; B. D. Gupta; S. K. Mehta



Light induced changes in the amorphous--crystalline silicon heterointerface  

NASA Astrophysics Data System (ADS)

The photostability of the amorphous--crystalline silicon heterointerface is investigated. It is revealed that the metastability of hydrogenated amorphous silicon (a-Si:H) causes significant light induced changes in the heterointerface. Unlike bulk a-Si:H, the photostability of the heterointerface is not controlled by the microstructural properties of a-Si:H but rather by the initial heterointerface properties. Interfaces that initially have low interface defect density show the greatest degradation while those that initially have high interface defect density actually show light-induced improvement. It is shown that the degree of light induced change in the interface defect density is linearly proportional to the natural logarithm of the initial interface defect density. Further, it is revealed that the kinetics of light-induced change in the heterointerface defect density can be faster or slower than light-induced changes in bulk a-Si:H films depending on the initial properties of the heterointerface. Light soaking measurements on heterointerfaces with doped a-Si:H films reveal that interface defect density of these structures improves with light soaking. It is proposed that this is caused by a combination of the high initial interface defect density of samples using doped a-Si:H films and reduced generation of defects near the heterointerface due to the enhanced field effect provided by the doped films.

Mahtani, Pratish; Varache, Renaud; Jovet, Bastien; Longeaud, Christophe; Kleider, Jean-Paul; Kherani, Nazir P.



Radiation-Induced Effects on Microstructure  

SciTech Connect

Irradiation of materials with particles that are sufficiently energetic to create atomic displacements can induce significant microstructural alteration, ranging from crystalline-to-amorphous phase transitions to the generation of large concentrations of point defect or solute aggregates in crystalline lattices. These microstructural changes typically cause significant changes in the physical and mechanical properties of the irradiated material. A variety of advanced microstructural characterization tools are available to examine the microstructural changes induced by particle irradiation, including electron microscopy, atom probe field ion microscopy, X-ray scattering and spectrometry, Rutherford backscattering spectrometry, nuclear reaction analysis, and neutron scattering and spectrometry. Numerous reviews, which summarize the microstructural changes in materials associated with electron and heavy ion or neutron irradiation, have been published. These reviews have focused on pure metals as well as model alloys, steels, and ceramic materials. In this chapter, the commonly observed defect cluster morphologies produced by particle irradiation are summarized and an overview is presented on some of the key physical parameters that have a major influence on microstructural evolution of irradiated materials. The relationship between microstructural changes and evolution of physical and mechanical properties is then summarized, with particular emphasis on eight key radiation-induced property degradation phenomena. Typical examples of irradiated microstructures of metals and ceramic materials are presented. Radiation-induced changes in the microstructure of organic materials such as polymers are not discussed in this overview.

Zinkle, Steven J [ORNL



Radiation effects in crystalline ceramics for the immobilization of high-level nuclear waste and plutonium  

Microsoft Academic Search

This review provides a comprehensive evaluation of the state-of-knowledge of radiation effects in crystalline ceramics that may be used for the immobilization of high-level nuclear waste and plutonium. The current understanding of radiation damage processes, defect generation, microstructure development, theoretical methods, and experimental methods are reviewed. Fundamental scientific and technological issues that offer opportunities for research are identified. The most

W. J. Weber; R. C. Ewing; C. R. A. Catlow; T. Diaz de La Rubia; L. W. Hobbs; C. Kinoshita; Hj. Matzke; A. T. Motta; M. Nastasi; E. H. K. Salje; E. R. Vance; S. J. Zinkle



Radiation Damage in Crystalline Nuclear-Waste Solids.  

National Technical Information Service (NTIS)

Radiation damage in nuclear wastes is shown to be linked to decay of the actinide elements, particularly Cm and Am. Both alpha-recoil damage in actinide-containing phases and alpha bombardment of all phases must be considered. Phases either remain crystal...

R. P. Turcotte W. J. Weber F. P. Roberts



Radiation-induced optic neuropathy  

Microsoft Academic Search

Radiation-induced optic neuropathy (RION) is a devastating late complication of radiotherapy to the anterior visual pathway resulting in acute, profound, irreversible visual loss. It is thought to be a result of radiation necrosis of the anterior visual pathway. Visual loss may be unilateral or bilateral; simultaneous or sequential. RION occurs commonly between 10-20 months, with an average of 18 months

Helen V. Danesh-Meyer



Tensile and tribological properties of high-crystallinity radiation crosslinked UHMWPE  

SciTech Connect

Osteolysis due to particulate wear debris associated with ultrahigh molecular weight polyethylene (UHMWPE) components of total joint replacement prostheses has been a major factor determining their in vivo lifetime. In recent years, radiation crosslinking has been employed to decrease wear rates in PE components, especially in acetabular cups of total hip replacement prostheses. A drawback of radiation crosslinking is that it leads to a crosslinked PE (or XPE) with lower mechanical properties compared with uncrosslinked PE. In contrast, high-crystallinity PEs are known to have several mechanical properties higher than conventional PE. In this study, we hypothesized that increasing the crystallinity of radiation crosslinked and remelted XPE would result in an increase in tensile properties without compromising wear resistance. High-pressure crystallization was performed on PE and XPE and analyzed for the resulting morphological alterations using differential scanning calorimeter, low voltage scanning electron microscopy, and ultrasmall angle X-ray scattering. Uniaxial tensile tests showed that high-pressure crystallization increased the tensile modulus and yield stress in both PE and XPE, decreased the ultimate strain and ultimate stress in PE but had no significant effect on ultimate strain or ultimate stress in XPE. Multidirectional wear tests demonstrated that high-pressure crystallization decreased the wear resistance of PE but had no effect on the wear resistance of XPE. In conclusion, this study shows that high-pressure crystallization can be effectively used to increase the crystallinity and modulus of XPE without compromising its superior wear resistance compared with PE.

Bistolfi, Alessandro; Turell, Mary Beth; Lee, Ying-Lung; Bellare, Anuj; (BWH)



Deficiency of ?B crystallin augments ER stress induced apoptosis by enhancing mitochondrial dysfunction  

PubMed Central

Endoplasmic reticulum (ER) stress is linked to several pathological conditions including age-related macular degeneration. Excessive ER stress initiates cell death cascades which are mediated, in part, through mitochondrial dysfunction. Here, we identify ?B crystallin as an important regulator of ER stress-induced cell death. Retinal pigment epithelial (RPE) cells from ?B crystallin (?/?) mice, and human RPE cells transfected with ?B crystallin siRNA, are more vulnerable to ER stress induced by tunicamycin. ER stress-mediated cell death is associated with increased levels of reactive oxygen species, depletion of glutathione in mitochondria, decreased superoxide dismutase activity, increased release of cytochrome c and activation of caspases 3 and 4. The ER stress signaling inhibitors, salubrinal and 4-(2-aminoethyl) benzenesulfonyl fluoride, decrease mitochondrial damage and reduce RPE apoptosis induced by ER stress. Prolonged ER stress decreases levels of ?B crystallin, thus exacerbating mitochondrial dysfunction. Overexpression of ?B crystallin protects RPE cells from ER stress-induced apoptosis by attenuating increases in Bax, CHOP, mitochondrial permeability transition, and cleaved caspase 3. Thus, these data collectively demonstrate that ?B crystallin provides critical protection of mitochondrial function during ER stress-induced RPE apoptosis.

Dou, Guorui; Sreekumar, Parameswaran G; Spee, Christine; He, Shikun; Ryan, Stephen J; Kannan, Ram; Hinton, David R



Crystalline polymorphism induced by charge regulation in ionic membranes.  


The crystallization of molecules with polar and hydrophobic groups, such as ionic amphiphiles and proteins, is of paramount importance in biology and biotechnology. By coassembling dilysine (+2) and carboxylate (-1) amphiphiles of various tail lengths into bilayer membranes at different pH values, we show that the 2D crystallization process in amphiphile membranes can be controlled by modifying the competition of long-range and short-range interactions among the polar and the hydrophobic groups. The pH and the hydrophobic tail length modify the intermolecular packing and the symmetry of their crystalline phase. For hydrophobic tail lengths of 14 carbons (C14), we observe the coassembly into crystalline bilayers with hexagonal molecular ordering via in situ small- and wide-angle X-ray scattering. As the tail length increases, the hexagonal lattice spacing decreases due to an increase in van der Waals interactions, as demonstrated by atomistic molecular dynamics simulations. For C16 and C18 we observe a reentrant crystalline phase transition sequence, hexagonal-rectangular-C-rectangular-P-rectangular-C-hexagonal, as the solution pH is increased from 3 to 10.5. The stability of the rectangular phases, which maximize tail packing, increases with increasing tail length. As a result, for very long tails (C22), the possibility of observing packing symmetries other than rectangular-C phases diminishes. Our work demonstrates that it is possible to systematically exchange chemical and mechanical energy by changing the solution pH value within a range of physiological conditions at room temperature in bilayers of molecules with ionizable groups. PMID:24065818

Leung, Cheuk-Yui; Palmer, Liam C; Kewalramani, Sumit; Qiao, Baofu; Stupp, Samuel I; Olvera de la Cruz, Monica; Bedzyk, Michael J



[Radiation-induced cardiac disease].  


Radiation-induced effects may damage various cardiac structures chronically and cause heart valve dysfunction as well as occlusive lesions of coronary and other arteries exposed to radiation. A 72-year-old woman with a history of radiation treatment after breast cancer was admitted 25 years later with symptoms of tachycardia and acute dyspnea. We found valvular thickening, medium to severe valvular dysfunction and high grade occlusive coronary artery disease in proximal portions. The left subclavian artery also was affected. Surgical treatment was required immediately. Long-term follow-up cardiac evaluation even in asymptomatic patients is mandatory to uncover cardiac injuries by radiation. To lower the risk and maximize the benefit, early intervention by valvular replacement and myocardial revascularization is indicated. Restrictive myopathy and chronic pericarditis increase risk and have to be clarified. Diagnosis in these radiation exposed patients can be made by typical findings. Echocardiography is of eminent relevancy. PMID:14634766

Andresen, H; Kaag, N; Meinhardt, A; Potratz, J



Ripple structure of crystalline layers in ion-beam-induced Si wafers  

SciTech Connect

Ion-beam-induced ripple formation in Si wafers was studied by two complementary surface sensitive techniques, namely atomic force microscopy (AFM) and depth-resolved x-ray grazing incidence diffraction (GID). The formation of ripple structure at high doses ({approx}7x10{sup 17} ions/cm{sup 2}), starting from initiation at low doses ({approx}1x10{sup 17} ions/cm{sup 2}) of ion beam, is evident from AFM, while that in the buried crystalline region below a partially crystalline top layer is evident from GID study. Such ripple structure of crystalline layers in a large area formed in the subsurface region of Si wafers is probed through a nondestructive technique. The GID technique reveals that these periodically modulated wavelike buried crystalline features become highly regular and strongly correlated as one increases the Ar ion-beam energy from 60 to 100 keV. The vertical density profile obtained from the analysis of a Vineyard profile shows that the density in the upper top part of ripples is decreased to about 15% of the crystalline density. The partially crystalline top layer at low dose transforms to a completely amorphous layer for high doses, and the top morphology was found to be conformal with the underlying crystalline ripple.

Hazra, S.; Chini, T.K.; Sanyal, M.K.; Grenzer, J.; Pietsch, U. [Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Institut fur Physik, Universitat Potsdam, 14415 Potsdam (Germany)



?B-Crystallin Protects Retinal Tissue during Staphylococcus aureus- Induced Endophthalmitis?  

PubMed Central

Bacterial infections of the eye highlight a dilemma that is central to all immune-privileged sites. On the one hand, immune privilege limits inflammation to prevent bystander destruction of normal tissue and loss of vision. On the other hand, bacterial infections require a robust inflammatory response for rapid clearance of the pathogen. We demonstrate that the retina handles this dilemma, in part, by activation of a protective heat shock protein. During Staphylococcus aureus-induced endophthalmitis, the small heat shock protein ?B-crystallin is upregulated in the retina and prevents apoptosis during immune clearance of the bacteria. In the absence of ?B-crystallin, mice display increased retinal apoptosis and retinal damage. We found that S. aureus produces a protease capable of cleaving ?B-crystallin to a form that coincides with increased retinal apoptosis and tissue destruction. We conclude that ?B-crystallin is important in protecting sensitive retinal tissue during destructive inflammation that occurs during bacterial endophthalmitis.

Whiston, Emily A.; Sugi, Norito; Kamradt, Merideth C.; Sack, Coralynn; Heimer, Susan R.; Engelbert, Michael; Wawrousek, Eric F.; Gilmore, Michael S.; Ksander, Bruce R.; Gregory, Meredith S.



Mixing-Induced Anisotropic Correlations in Molecular Crystalline Systems  

NASA Astrophysics Data System (ADS)

We investigate the structure of mixed thin films composed of pentacene and diindenoperylene using x-ray reflectivity and grazing incidence x-ray diffraction. For equimolar mixtures we observe vanishing in-plane order coexisting with an excellent out-of-plane order, a yet unreported disordering behavior in binary mixtures of organic semiconductors, which are crystalline in their pure form. One approach to rationalize our findings is to introduce an anisotropic interaction parameter in the framework of a mean field model. By comparing the structural properties with those of other mixed systems, we discuss the effects of sterical compatibility and chemical composition on the mixing behavior, which adds to the general understanding of interactions in molecular mixtures.

Aufderheide, A.; Broch, K.; Novák, J.; Hinderhofer, A.; Nervo, R.; Gerlach, A.; Banerjee, R.; Schreiber, F.



Crystalline silica induces apoptosis in human endothelial cells in vitro.  


We investigated whether incubation of cultured human aortic endothelial cells (HAEC) with crystalline silica at the concentration 1 cm2/ml (chosen on the basis of a pilot experiment) leads to alterations typical of apoptosis. The binding of annexin V as early, and DNA fragmentation as late events of apoptosis were measured besides the number of cells with depolarized mitochondria. The generation of reactive oxygen species (ROS) by HAEC in presence of silica was determined as well as silica ability to in vitro generate hydroxyl radicals was investigated. After 18 h of silica incubation, about 30% of viable cells bound annexin V. After 24 h of silica treatment, the percentage of cells with fragmented DNA (Tunel positive) was 27% and it increased up to 50% after 48 h, whereas in untreated cells this percentage was 7% and 11% after 24 and 48 h, respectively. The presence of fragmented DNA in cells treated with silica was confirmed by agarose gel electrophoresis. In agreement with these results showing an induction of HAEC apoptosis by silica incubation, the number of cells with depolarized mitochondria was significantly higher after silica treatment as compared to the control. Apoptosis was also obtained with silica added to aliquots of anti-C5a-absorbed-medium. In the cells exposed to silica there was a significant increasing of ROS generation in comparison to the untreated cells. Apoptosis might be due to peroxidative stress since silica can generate hydroxyl radicals. PMID:15242185

Santarelli, L; Recchioni, R; Moroni, F; Marcheselli, F; Governa, M



Radiation-induced reactions in polymer films  

NASA Astrophysics Data System (ADS)

Since the 1950's, there has been a considerable interest in the effects of ionizing radiation on the physical properties of polymer systems. Radiation induced chemical changes that were found to be helpful in producing specialty polymers, but also potentially harmful by degrading the physical performance of the material. Therefore, solute molecules, which act as excited state quenchers, and free radical scavengers, have been incorporated into the polymers in order to regulate the crosslinking, scission and desaturation reactions. This work is focused on using spectroscopic techniques to characterize the physical properties of polymeric media and the reactions occurring within them following pulsed radiolysis. This is done primarily by using arene doped polymer films which have highly absorbing excited states and radical ions that are easily monitored by transient studies. The probes are used to characterize the polymeric microenvironment, to monitor reaction rates, and to interfere in the radical reactions. Photophysical and photochemical characterization of partially crystalline polyethylene complements data previously obtained by conventional physical techniques for polymer characterization. Probe molecules are excluded from crystalline zones and distributed in a networked structure of amorphous zones. Upon high energy radiolysis, it is found that polyolefin systems efficiently donate all radical ions and excited states to the solute molecules, even when the energy is absorbed within the polymer crystalline zones. Studies of the subsequent reactions of the solute excited states and radical ions reveal information about their long term effectiveness as protectants. It is found that highly excited states formed by the recombination of solute radical ions are energetic enough to cause dissociation of halo-arenes. Also, arenes are found to become attached to the polymer chain through a polymer-aryl radical intermediate. These intermediates have been isolated and photophysically characterized so that they can be easily identified in future experiments where they may be important reactants. Alternatively, photophysical probes are attached to polymer chains by radical copolymerization of pyrene acrylic acid and methyl acrylate with the underivatized monomer. These probes did not inhibit the polymerization reaction, and were found to be useful in monitoring polymerization rates during the early stages of polymerization.

Biscoglio, Michael Benedict


Influence of interface on radiation effects of crystalline polymer-radiation effects on polyamide-1010 containing BMI  

NASA Astrophysics Data System (ADS)

Aimed at saving the radiation dose required to crosslinking the polyamide-1010, BMI/PA1010 systems containing different amounts of difunctional crosslinking agent N,N'-bis-maleimide-4,4'-biphenyl methane (BMI) were prepared and the structure changes at the crystallographic and supermolecular levels before and after irradiation were studied by using WAXD, SAXS, and DSC techniques. It was found that by incorporation of BMI the microcrystal size L100 is lowered due to the formation of hydrogen bond between the carbonyl oxygen of BMI and the amide hydrogen of PA1010 in the hydrogen bonded plane, and the overall crystallinity Wc is also decreased. The presence of BMI causes the crystal lamella thickness dc to decrease and greatly thickens the transition zone dtr between the crystalline and amorphous regions. As for the irradiated specimen, the maximum increments in the L100 and Wc against dose curves decrease with BMI content, and the interception point Di, at which the L100 and Wc curves intercept their respective horizontal line of L100/L0100 and Wc/W0c=1, shift to lower dose with an increase in BMI concentration. In addition, the mechanism of the radiation chemical reactions in the three different phases under the action of BMI are discussed with special focus on the interface region.

Zhang, L.; Zhang, H.; Chen, D.



Hydrogeologic controls on induced seismicity in crystalline basement rocks due to fluid injection into basal reservoirs.  


A series of Mb 3.8-5.5 induced seismic events in the midcontinent region, United States, resulted from injection of fluid either into a basal sedimentary reservoir with no underlying confining unit or directly into the underlying crystalline basement complex. The earthquakes probably occurred along faults that were likely critically stressed within the crystalline basement. These faults were located at a considerable distance (up to 10?km) from the injection wells and head increases at the hypocenters were likely relatively small (?70-150?m). We present a suite of simulations that use a simple hydrogeologic-geomechanical model to assess what hydrogeologic conditions promote or deter induced seismic events within the crystalline basement across the midcontinent. The presence of a confining unit beneath the injection reservoir horizon had the single largest effect in preventing induced seismicity within the underlying crystalline basement. For a crystalline basement having a permeability of 2?×?10(-17) ?m(2) and specific storage coefficient of 10(-7) /m, injection at a rate of 5455?m(3) /d into the basal aquifer with no underlying basal seal over 10?years resulted in probable brittle failure to depths of about 0.6?km below the injection reservoir. Including a permeable (kz ?=?10(-13) ?m(2) ) Precambrian normal fault, located 20?m from the injection well, increased the depth of the failure region below the reservoir to 3?km. For a large permeability contrast between a Precambrian thrust fault (10(-12) ?m(2) ) and the surrounding crystalline basement (10(-18) ?m(2) ), the failure region can extend laterally 10?km away from the injection well. PMID:23745958

Zhang, Yipeng; Person, Mark; Rupp, John; Ellett, Kevin; Celia, Michael A; Gable, Carl W; Bowen, Brenda; Evans, James; Bandilla, Karl; Mozley, Peter; Dewers, Thomas; Elliot, Thomas



Radiation-induced leiomyosarcoma of the oropharynx  

PubMed Central

Leiomyosarcoma is a malignant mesenchymal tumor originating from smooth muscle cells, which most frequently develops in the myometrium and in the gastro-intestinal tract. Reviewing the international literature, radiation-induced sarcoma arise in 0.035 to 0.2 % of all irradiated patients. Especially in the head and neck region, radiation-induced leiomyosarcoma is an extremely rare lesion. The authors report a case of a radiation-induced leiomyosarcoma of the tonsillar region of the oropharynx in a 51-year-old male patient, who had undergone radiation therapy of this region 38 years before. The lesion was treated by radical surgery. Diagnostic steps, histological presentation and therapy are described in detail and the literature concerning radiation induced malignancies in general as well as radiation induced leiomyosarcoma in particular is reviewed. The highlights of this case are an extremely uncommon location and a rare pathological entity of radiation induced malignancies.

Pfeiffer, Jens; Boedeker, Carsten Christof; Ridder, Gerd Jurgen; Maier, Wolfgang; Kayser, Gian



Severe creep of a crystalline metallic layer induced by swift-heavy-ion irradiation  

Microsoft Academic Search

The aim of the experiments presented in this paper was to study the mechanisms leading to the atomic transport process (plastic deformation) induced in amorphous solids by GeV heavy-ion irradiation. Ni3B\\/Au\\/Ni3B sandwiches, composed of a crystalline Au layer of various thicknesses and of two amorphous Ni3B layers, were irradiated at liquid nitrogen temperature with 500-MeV iodine ions. The Rutherford backscattering

F. Garrido; A. Benyagoub; A. Chamberod; J.-C. Dran; A. Dunlop; S. Klaumünzer; L. Thomé



Trans-cis photoizomerization-induced tilted anchoring in photoactive guest-host liquid crystalline systems  

NASA Astrophysics Data System (ADS)

We report on UV light-induced tilted anchoring in a mixture of the nematic liquid crystal N-(4-methoxybenzylidene)-4-butylaniline (MBBA) with a photoactive liquid crystalline azo dye (4-hexyloxybenzoloxy-4'-cyanoazobenzene) at 1 wt.% concentration. The surface anchoring found in this guest-host liquid-crystal system confined in homeotropic thin films is due to trans-cis photoizomerization of the guest azo molecules upon UV light.

Marinov, Y. G.; Hadjichristov, G. B.; Petrov, A. G.; Sridevi, S.; Hiremath, U. S.; Yelamaggad, C. V.; Prasad, S. K.



Milling induces disorder in crystalline griseofulvin and order in its amorphous counterpart  

SciTech Connect

This study investigates two apparently similar thermal signatures, shaped as bimodal exotherms, observed when either the crystalline or the amorphous from of the drug are subjected to milling. Crystalline griseofulvin was cryomilled and the (quenched-melt) amorphous form was subjected to either cryomilling or grinding. The thermal and surface properties of the resulting samples were analyzed using differential scanning calorimetry (DSC) and surface energy analysis. After milling, both the crystalline and the amorphous material revealed visually similar bimodal exothermic events when the heating rate was 20 C min{sup -1}. Under different heating rates, the pair of DSC peaks for the bimodal exotherm of each material behaved entirely different from each other. The two peaks of the bimodal event, as well as the glass transition, can be kinetically resolved for the ground amorphous form using standard mode DSC. In contrast, similar analysis was unable to resolve the bimodal exotherm or a glass transition in the case of the cryomilled crystals. Furthermore, cryomilled crystals do not exhibit a glass transition even when analyzed using modulated DSC. Synchrotron sourced X-ray analysis revealed that grinding the amorphous material results in the nucleation and growth of the crystalline form. Milling thus induces disorder in the crystals of griseofulvin but induces order in the amorphous form of the drug. The surface of the two milled systems consistently exhibited different energetics under a wide range of relative humidity conditions. These findings suggest that cryomilling induces both bulk and surface disorder, specifically, a certain level of dislocations on the crystal. In contrast, grinding the amorphous material lowers the activation energy for crystal formation, inducing nuclei formation and growth throughout the amorphous matrix.

Otte, Andrew; Zhang, Yan; Carvajal, M. Teresa; Pinal, Rodolfo (Purdue)



Seeded growth induced amorphous to crystalline transformation of niobium oxide nanostructures.  


A novel high-temperature synthesis of niobium oxide nanostructures has been developed through an amorphous intermediate that crystallizes into anisotropic crystalline structures through a complex mechanism of nucleation-dissolution-selective growth induced by seeded growth. The amorphous materials formed by the thermolysis of niobium oleate transformed into crystalline platelets, wires or bundled wires after the injection of additional niobium oleate at different temperatures. The temperature of the solution during injection of the additional precursor determined the morphology of the formed crystalline structure. The time- and temperature-dependent evolution of the niobium oxide nanostructures demonstrates that amorphous materials progressively turned to crystalline materials. We tuned the size of wires and platelets by the consecutive injection of the precursor solution into the reaction mixture under isothermal conditions. With the sequential injection of the precursor solution, we demonstrate that the anisotropic growth of individual nanowires occurs exclusively along the ends, without the formation of any new nuclei. A mechanism for the transformation of well-defined platelets from wires has been proposed and is due to the exclusive loss of mass at the ends of the wires while growth of the platelets initially occurs along the (001) direction which is then replaced by the (110) face. PMID:22286141

Jana, Subhra; Rioux, Robert M



Electrical properties changes induced by electron radiation at TiO2/Si interface  

NASA Astrophysics Data System (ADS)

TiO2/Si structures were fabricated by electron beam evaporation, and exposed to electron beam irradiation to investigate their electrical properties using the high frequency capacitance-voltage measurements. It was found that samples annealed in oxygen became more radiation resistant than un-annealed samples, which can be explained by the Ti valence variations induced by radiation. The samples were characterized by X-ray diffraction to show the Ti2O3 crystalline phase transformed to anatase-crystalline phase after oxygen annealing.

Liu, Chengshi; Wu, Dengxue; Zhao, Lili; Liao, Zhijun



Radiation-induced moyamoya syndrome  

SciTech Connect

Purpose: The moyamoya syndrome is an uncommon late complication after radiotherapy (RT). Methods and Materials: A PubMed search of English-language articles, with radiation, radiotherapy, and moyamoya syndrome used as search key words, yielded 33 articles from 1967 to 2002. Results: The series included 54 patients with a median age at initial RT of 3.8 years (range, 0.4 to 47). Age at RT was less than 5 years in 56.3%, 5 to 10 years in 22.9%, 11 to 20 years in 8.3%, 21 to 30 years in 6.3%, 31 to 40 years in 2.1%, and 41 to 50 years in 4.2%. Fourteen of 54 patients (25.9%) were diagnosed with neurofibromatosis type 1 (NF-1). The most common tumor treated with RT was low-grade glioma in 37 tumors (68.5%) of which 29 were optic-pathway glioma. The average RT dose was 46.5 Gy (range, 22-120 Gy). For NF-1-positive patients, the average RT dose was 46.5 Gy, and for NF-1-negative patients, it was 58.1 Gy. The median latent period for development of moyamoya syndrome was 40 months after RT (range, 4-240). Radiation-induced moyamoya syndrome occurred in 27.7% of patients by 2 years, 53.2% of patients by 4 years, 74.5% of patients by 6 years, and 95.7% of patients by 12 years after RT. Conclusions: Patients who received RT to the parasellar region at a young age (<5 years) are the most susceptible to moyamoya syndrome. The incidence for moyamoya syndrome continues to increase with time, with half of cases occurring within 4 years of RT and 95% of cases occurring within 12 years. Patients with NF-1 have a lower radiation-dose threshold for development of moyamoya syndrome.

Desai, Snehal S. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, Houston, TX (United States); Paulino, Arnold C. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, Houston, TX (United States)]. E-mail:; Mai, Wei Y. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, Houston, TX (United States); Teh, Bin S. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, Houston, TX (United States)



Radiation-induced parotid cancer  

SciTech Connect

A retrospective analysis of 72 cases of primary malignant tumors of the parotid gland treated at the University of Illinois Hospital, Chicago, from 1950 through 1978 revealed that six of these had developed from two to 24 years after irradiation of the head or neck for various benign and malignant neoplastic conditions. At the time of irradiation, ages ranged from 7 to 73 years; the sex distribution was equal. From our findings and those in 26 cases reported by various other authors, the following criteria are proposed for the designation of a parotid tumor as being radiation induced: (1) well-documented radiation exposure; (2) part of irradiation must incorporate the gland in which the cancer subseqently arises; (3) exposure to a minimum of 300 rads; and (4) minimum latent period of two years. In view of the widespread use in the past of heat and neck irradiation of benign neoplastic disease, the surgeon should be aware of this possible link with parotid gland tumor.

Walker, M.J.; Chaudhuri, P.K.; Wood, D.C.; Das Gupta, T.K.



Radiation Induces Acute Alterations in Neuronal Function  

Microsoft Academic Search

Every year, nearly 200,000 patients undergo radiation for brain tumors. For both patients and caregivers the most distressing adverse effect is impaired cognition. Efforts to protect against this debilitating effect have suffered from inadequate understanding of the cellular mechanisms of radiation damage. In the past it was accepted that radiation-induced normal tissue injury resulted from a progressive reduction in the

Peter H. Wu; Steven Coultrap; Chelsea Pinnix; Kurtis D. Davies; Ramesh Tailor; Kian K. Ang; Michael D. Browning; David R. Grosshans



Radiation-induced leukemias in ankylosing spondylitis  

SciTech Connect

Three cases of leukemia occurred in patients with ankylosing spondylitis treated by radiotherapy. In each case, the leukemic process exhibited bizarre features suggesting that radiation is likely to induce atypical forms of leukemia possessing unusual attributes not shared by spontaneously developing leukemia. The likely distinctive aspects of radiation-induced leukemia are discussed.

Toolis, F. (Royal Infirmary, Edinburgh, UK); Potter, B.; Allan, N.C.; Langlands, A.O.



Radiation-induced defect centers in glass ceramics  

SciTech Connect

Electron spin resonance (ESR) was used to characterize the radiation-induced defect centers in low-thermal-expansion glass ceramics, including two types of Zerodur and Astrositall. The observed ESR spectra can be associated with different types of defect centers: a Zn/sup +/ center, several types of oxygen hole centers (OHCs), an aluminum-oxygen hole center (Al-OHC), an Fe/sup 3 +/ center, Ti/sup 3 +/ and Zr/sup 3 +/ centers, and three types of As centers. An Sb/sup 4 +/ center, which is not observed in Zerodur, is tentatively identified in Astrositall. From the effect of crystallization on the observed defect concentrations in Zerodur and computer simulation of the spectral lines of some of the centers, we infer that among the nine defect centers observed in the Zerodurs, the As-associated centers are located in the glassy phase and/or at the interface between the glassy and crystalline phases, Zn/sup +/ and Al-OHC are in the crystalline phase, and the rest (including most of the OHCs) are in the glassy phase. Radiation-induced compaction in these materials appears to be related to the generation of OHCs in the glass phase.

Tsai, T.E.; Friebele, E.J.; Griscom, D.L.; Pannhorst, W.



Medium-induced multi-photon radiation  

NASA Astrophysics Data System (ADS)

We study the spectrum of multi-photon radiation off a fast quark in medium in the BDMPS/ASW approach. We reproduce the medium-induced one-photon radiation spectrum in dipole approximation, and go on to calculate the two-photon radiation in the Molière limit. We find that in this limit the LPM effect holds for medium-induced two-photon ladder emission.

Ma, Hao; Salgado, Carlos A.; Tywoniuk, Konrad



Hypopharyngeal carcinoma after radiation for tuberculosis: radiation-induced carcinoma.  


Radiation may cause radiation-induced cancers after a long latency period. In a group of 111 patients surgically treated for hypopharyngeal carcinoma, patients previously treated with radiotherapy for tuberculosis in the neck were compared to patients without previous radiotherapy. Seven patients (7.4%) underwent radiotherapy (median age 15 years) and developed a hypopharyngeal carcinoma (median age 70 years, median latency period 54.4 year). Considering this long latency period and the localisation in the previous radiation field these tumours can be classified as potentially radiation-induced carcinomas. Patients with potentially radiation-induced carcinomas were significantly older when the hypopharyngeal carcinoma was diagnosed (p=0.048), were more frequently females (p=0.05) and had a worse 5-year regional control rate (p=0.048). When radiotherapy is considered in young patients the risk of induction of tumours has to be kept in mind. PMID:20656544

van der Putten, Lisa; de Bree, Remco; Kuik, Dirk J; Rietveld, Derek H F; Langendijk, Johannes A; Leemans, C René



Large deformation compression induced crystallinity degradation of conventional and highly crosslinked UHMWPEs.  


The effect of a large compressive plastic deformation on the melt temperature (Tm), lamellar thickness, crystallinity, and density of four UHMWPEs (two conventional and two highly crosslinked) was examined. The materials were prepared from a single batch of medical grade GUR 1050 resin (Ticona, Bayport, TX, USA). The two conventional UHMWPEs were as-received (virgin) and gamma radiation sterilized at 30 kGy in a nitrogen atmosphere (radiation sterilized). The two highly crosslinked UHMWPEs were each irradiated at 100 kGy and then post-processed with one of either two thermal treatments: annealing, which was done below the melt transition temperature (Tm), at 110 degrees C for 2h (110 degrees C-annealed); and, remelting, which was done above Tm, at 150 degrees C (150 degrees C-remelted). Differences in changes upon compression between the materials were examined using ANCOVA analyses. The 150 degrees C-remelted material showed a significant change in Tm and lamellar thickness upon compressive plastic deformation whereas the other three UHMWPE materials did not. However, all of the materials showed significantly decreased crystallinity and density upon compressive deformation. The findings of this study support that microstructural evolution during compressive deformation is a function of UHMWPE formulation, as affected by irradiation and post-irradiation heat treatment. PMID:15935468

Sobieraj, Michael C; Kurtz, Steven M; Rimnac, Clare M



Modeling radiation-induced cell cycle delays  

Microsoft Academic Search

Ionizing radiation is known to delay the cell cycle progression. In particular after particle exposure significant delays\\u000a have been observed and it has been shown that the extent of delay affects the expression of damage, such as chromosome aberrations.\\u000a Thus, to predict how cells respond to ionizing radiation and to derive reliable estimates of radiation risks, information\\u000a about radiation-induced cell

Anna Ochab-Marcinek; Ewa Gudowska-Nowak; Elena Nasonova; Sylvia Ritter



Crystallinity in starch bioplastics  

Microsoft Academic Search

Thermoplastic starch (TPS) materials have been prepared by kneading, extrusion, compression moulding and injection moulding of several native starches with the addition of glycerol as a plasticizer. Two types of crystallinity can be distinguished in TPS directly after processing: (i) residual crystallinity: native A-, B- or C-type crystallinity caused by incomplete melting of starch during processing; (ii) processing-induced crystallinity: amylose

Jeroen J. G. van Soest; S. H. D. Hulleman; D. de Wit; J. F. G. Vliegenthart



REVIEW ARTICLE: Sputter-induced crystalline layers and epitaxial overlayers on quasicrystal surfaces  

NASA Astrophysics Data System (ADS)

We present here an overview of surface and interface studies on various quasicrystals, focusing on areas where reflection high-energy electron diffraction plays an important role. Subjects included here are sputter-induced crystalline layers, surface alloying and epitaxial films. These phenomena are observed on the high symmetry surface of Al-based quasicrystals, such as decagonal Al-Ni-Co, icosahedral (i) Al-Cu-Fe and i-Al-Cu-Ru. For comparison, studies on i-Ag-In-Yb quasicrystal, an isostructure of the binary i-Cd-Yb quasicrystal, and ?'-Al-Pd-Mn approximant are also included.

Shimoda, M.; Sharma, H. R.



Radiation-induced gene responses  

SciTech Connect

In the process of identifying genes that are differentially regulated in cells exposed to ultraviolet radiation (UV), we identified a transcript that was repressed following the exposure of cells to a combination of UV and salicylate, a known inhibitor of NF-kappaB. Sequencing this band determined that it has identify to lactate dehydrogenase, and Northern blots confirmed the initial expression pattern. Analysis of the sequence of the LDH 5` region established the presence of NF-kappaB, Sp1, and two Ap-2 elements; two partial AP- 1; one partial RE, and two halves of E-UV elements were also found. Electromobility shift assays were then performed for the AP-1, NF- kappaB, and E-UV elements. These experiments revealed that binding to NF-kappaB was induced by UV but repressed with salicylic acid; UV did not affect AP-1 binding, but salicylic acid inhibited it alone or following UV exposure; and E-UV binding was repressed by UV, and salicylic acid had little effect. Since the binding of no single element correlated with the expression pattern of LDH, it is likely that multiple elements govern UV/salicylate-mediated expression.

Woloschak, G.E.; Paunesku, T.; Shearin-Jones, P.; Oryhon, J.



Channeling and Radiation of Electrons in Silicon Single Crystals and Si1-xGex Crystalline Undulators  

NASA Astrophysics Data System (ADS)

The phenomenon of channeling and the basic features of channeling radiation emission are introduced in a pedestrian way. Both, radiation spectra as well as dechanneling length measurements at electron beam energies between 195 and 855 MeV feature quantum state phenomena for the (110) planar potential of the silicon single crystals. Radiation from a crystalline undulator, produced at the Aarhus University (UAAR), has been investigated at the Mainz Microtron electron accelerator facility MAMI. The 4-period epitaxially grown strained layer Si1-xGex undulator had a period length ?u = 9.9 ?m. At a beam energy of 375 MeV a broad excess yield around the theoretically expected photon energy of 0.132 MeV has been observed. Model calculations on the basis of synchrotron-like radiation emission suggest that evidence for a weak undulator effect has been observed.

Backe, H.; Krambrich, D.; Lauth, W.; Andersen, K. K.; Lundsgaard Hansen, J.; Uggerhøj, Ulrik I.



UV-A-induced structural and functional changes in human lens deamidated ?B-crystallin  

PubMed Central

Purpose To determine comparative effects of ultraviolet (UV)-A irradiation on structural and functional properties of wild type (WT) ?B-crystallin and its three deamidated mutant proteins (?B-Asn78Asp, ?B-Asn146Asp, and ?B-Asn78/146Asp). Methods Three deamidated mutants previously generated from recombinant WT ?B-crystallin, using a site-specific mutagenesis procedure as previously described [32], were used. The WT ?B-crystallin and its three deamidated species were exposed to UV-A light (320–400 nm) at intensities of 20 or 50 J/cm2. The UV-A-unexposed and UV-A-exposed preparations were examined for their chaperone activity, and their activities were correlated with the UV-A-induced structural changes. The structural properties studied included dimerization and degradation, intrinsic tryptophan (Trp) fluorescence, ANS (8-anilino-1-naphthalenesulfate)-binding, far ultraviolet circular dichroism (UV-CD) spectral analysis, molecular sizes by dynamic light scattering, and oxidation of Trp and methionine (Met) residues. Results The WT ?B-crystallin and its three deamidated mutant proteins showed enhanced dimerization to 40 kDa species and partial degradation with increasing doses during UV-A-exposure. Compared to the deamidation of asparagines (Asn) 78 residue to aspartic acid (Asp) or both Asn78 and Asn146 residues to Asp, the deamidation of Asn146 residue to Asp resulted in a greater loss of chaperone activity. The UV-A-induced loss of chaperone activity due to structural changes was studied. The ANS-binding data suggested that the ?B-Asn146Asp mutant protein had a relatively compact structure and an increase in surface hydrophobic patches compared to WT and two other deamidated proteins. Similarly, UV-A-exposure altered the Trp microenvironment in the deamidated mutant proteins compared to the WT ?B-crystallin. Far-UV CD spectral analyses showed almost no changes among WT and deamidated species on UV-A-exposure except that the ?B-Asn146Asp mutant protein showed maximum changes in the random coil structure relative to WT ?B-crystallin and two other deamidated proteins. The UV-A-exposure also resulted in the aggregation of WT and the three deamidated mutant proteins with species of greater mass compared to the non-UV-A exposed species. Among the four spots recovered after two-dimensional (2D)-gel electrophoresis from WT and the three deamidated species, the Met and Trp residues of ?B-Asn146Asp mutant showed maximum oxidation after UV-A exposure, which might account for its greater loss in chaperone activity compared to WT ?B-crystallin and two other deamidated species. Conclusions After UV-A-exposure, the deamidated ?B-Asn146Asp mutant protein showed a complete loss of chaperone activity compared to WT ?B and ?B-Asn78Asp and ?B-Asn78/146Asp deamidated species. Apparently, this loss of chaperone activity was due to oxidative changes leading to its greater structural alteration compared to other ?B-species.

Mafia, Kerri; Gupta, Ratna; Kirk, Marion; Wilson, L.; Barnes, Stephen



[Like anticataract agents, the antiaggregants of lens crystallin. Communication 2. Study of the impact of chaperon-like (protective) activity of short-chain peptides on the rate of UV-induced aggregation of betaL-crystallins by eximer laser].  


UV-induced aggregation of betaL-crystallin, one of the major lens proteins, was studied under its pulse radiation with XeCl laser at a wavelength of 308 nm. Unlike the in vitro tested dipeptides L-carnosine, N-acetyl carnosine, D-panthetine, and particularly their combination, the so-called new chaperon was demonstrated to slow down the rate of photoaggregatin of beta-crystallin. The new chaperon, a mixture of D-pathethine and N-acetyl carnosine was ascertained to protect a mixture of betaL- and alpha-crystallins from UV-induced aggregation to a greater extent than D-pathethine or N-acetyl carnosine used alone. An effective drug based on the new chaperon may be designed for the prevention of cataract in sight. PMID:18488460

Soustov, L V; Chelnokov, E V; Sapogova, N V; Bitiurin, N M; Nemov, V V; Karpova, O E; Sheremet, N L; Polunin, G S; Avetisov, S E; Ostrovski?, M A


Radiation-induced thyroid disease  

SciTech Connect

Ionizing radiation has been demonstrated to result in a number of changes in the human thyroid gland. At lower radiation dose levels (between 10 and 1500 rads), benign and malignant neoplasms appear to be the dominant effect, whereas at higher dose levels functional changes and thyroiditis become more prevalent. In all instances, the likelihood of the effect is related to the amount and type of radiation exposure, time since exposure, and host factors such as age, sex, and heredity. The author's current approach to the evaluation of patients with past external radiation therapy to the thyroid is discussed. The use of prophylactic thyroxine (T4) therapy is controversial. While T4 therapy may not be useful in preventing carcinogenesis when instituted many years after radiation exposure, theoretically T4 may block TSH secretion and stimulation of damaged cells to undergo malignant transformation when instituted soon after radiation exposure.

Maxon, H.R.



Radiation-induced accelerated coronary arteriosclerosis  

Microsoft Academic Search

There is a paucity of information on radiation-induced coronary heart disease. A young patient with myocardial infarction following mediastinal irradiation is described. The role of radiotherapy and chemotherapy on the subsequent development of coronary heart disease is discussed.

B. Mittal; M. Deutsch; M. Thompson; H. Lee Dameshek



Radiation-induced solution chlorination of PVC  

NASA Astrophysics Data System (ADS)

The high solubility in the usual solvents makes the chlorinated PVC most suitable for laquers, adhesives and fibres. For this reason, the radiation-induced solution chlorination of PVC in methylene chloride was studied. The results of many experiments show that during the reaction between chlorine and PVC the solvent (methylene chloride) is chlorinated only in a small percentage to chloroform (9.5%) and finally to tetrachloromethane (0.1%). It was found that the radiation-induced chlorinated PVC has the same structure as the thermally chlorinated polymer, while the thermal stability and the rate of degradation of the radiation products show the better data for application purposes.

Friese, K.; Hösselbarth, B.; Reinhardt, J.; Newe, R.



Formation and growth of nanoindentation-induced high pressure phases in crystalline and amorphous silicon  

NASA Astrophysics Data System (ADS)

Nanoindentation-induced formation of high pressure crystalline phases (Si-III and Si-XII) during unloading has been studied by Raman micro-spectroscopy, cross-sectional transmission electron microscopy (XTEM), and postindentation electrical measurements. For indentation in crystalline silicon (c-Si), rapid unloading (~1000 mN/s) results in the formation of amorphous silicon (a-Si) only; a result we have exploited to quench the formation of high pressure phases at various stages during unloading to study their formation and evolution. This reveals that seed volumes of Si-III and Si-XII form during the early stages of unloading with substantial volumes only forming after the pop-out event that occurs at about 50% of the maximum load. In contrast, high pressure phases form much more readily in an a-Si matrix, with substantial volumes forming without an observable pop-out event with rapid unloading. Postindentation electrical measurements have been used to further investigate the end phases and to identify differences between indentations which otherwise appear to be identical from the XTEM and Raman analyses.

Ruffell, S.; Bradby, J. E.; Williams, J. S.; Munroe, P.



Ionizing Radiation Induces Stemness in Cancer Cells  

PubMed Central

The cancer stem cell (CSC) model posits the presence of a small number of CSCs in the heterogeneous cancer cell population that are ultimately responsible for tumor initiation, as well as cancer recurrence and metastasis. CSCs have been isolated from a variety of human cancers and are able to generate a hierarchical and heterogeneous cancer cell population. CSCs are also resistant to conventional chemo- and radio-therapies. Here we report that ionizing radiation can induce stem cell-like properties in heterogeneous cancer cells. Exposure of non-stem cancer cells to ionizing radiation enhanced spherogenesis, and this was accompanied by upregulation of the pluripotency genes Sox2 and Oct3/4. Knockdown of Sox2 or Oct3/4 inhibited radiation–induced spherogenesis and increased cellular sensitivity to radiation. These data demonstrate that ionizing radiation can activate stemness pathways in heterogeneous cancer cells, resulting in the enrichment of a CSC subpopulation with higher resistance to radiotherapy.

Ghisolfi, Laura; Keates, Andrew C.; Hu, Xingwang; Lee, Dong-ki; Li, Chiang J.



[Quantification of radiation-induced genetic risk].  


Associated with technical advances of our civilization is a radiation- and chemically-induced increase in the germ cell mutation rate in man. This would result in an increase in the frequency of genetic diseases and would be detrimental to future generations. It is the duty of our generation to keep this risk as low as possible. The estimation of the radiation-induced genetic risk of human populations is based on the extrapolation of results from animal experiments. Radiation-induced mutations are stochastic events. The probability of the event depends on the dose; the degree of the damage does not. The different methods to estimate the radiation-induced genetic risk will be discussed. The accuracy of the predicted results will be evaluated by a comparison with the observed incidence of dominant mutations in offspring born to radiation exposed survivors of the Hiroshima and Nagasaki atomic bombings. These methods will be used to predict the genetic damage from the fallout of the reactor accident at Chernobyl. For the exposure dose we used the upper limits of the mean effective life time equivalent dose from the fallout values in the Munich region. According to the direct method for the risk estimation we will expect for each 100 to 500 spontaneous dominant mutations one radiation-induced mutation in the first generation. With the indirect method we estimate a ratio of 100 dominant spontaneous mutations to one radiation-induced dominant mutation. The possibilities and the limitations of the different methods to estimate the genetic risk will be discussed. The discrepancy between the high safety standards for radiation protection and the low level of knowledge for the toxicological evaluation of chemical mutagens will be emphasized. PMID:3589954

Ehling, U H



Light-induced point defect reactions of residual iron in crystalline silicon after aluminum gettering  

SciTech Connect

Deep level transient spectroscopy is used to study light-induced reactions of residual iron impurities after aluminum gettering (AlG) in crystalline silicon. White-light illumination at room temperature leads to the formation of a defect which is associated with a donor level at 0.33 eV above the valence band. This defect is stable up to about 175 deg. C where it dissociates reversibly in case of small iron concentrations and irreversibly for high iron concentrations. Since marker experiments using gold and platinum diffusion show a high vacancy concentration after AlG a tentative identification of the new defect as the metastable iron-vacancy pair is proposed.

Abdelbarey, D.; Kveder, V.; Schroeter, W.; Seibt, M. [IV. Physikalisches Institut der Georg-August-Universitaet Goettingen, Friedrich-Hund-Platz 1, D-37077 Goettingen (Germany)



Differences Between Charge Trapping States in Irradiated NanoCrystalline HfO2 and Non-Crystalline Hf Silicates  

Microsoft Academic Search

This paper provides an explanation for qualitative differences between radiation-induced charge trapping states in nano-crystalline HfO 2 and non-crystalline Hf silicate alloys in high-kappa gate stacks by combining electrical measurements with spectroscopic studies and theory. Differences in the observed electrical response to X-ray and gamma-ray irradiation are consistent with fundamental differences in electronic structures between high-kappa dielectrics that are nano-crystalline

G. Lucovsky; D. M. Fleetwood; S. Lee; H. Seo; R. D. Schrimpf; J. A. Felix; J. Lning; L. B. Fleming; M. Ulrich; D. E. Aspnes



On the pressure-induced loss of crystallinity in orthophosphates of zinc and calcium  

NASA Astrophysics Data System (ADS)

A recently suggested mechanism for the stress memory of various metal phosphates is investigated experimentally. Based on first-principles simulations [N. J. Mosey et al., Science 307, 1612 (2005)], it had been argued that atoms with flexible coordination, such as zinc or heavy-metal cations, act as network-forming agents, undergoing irreversible pressure-induced changes in bonding that lead to increased connectivity between phosphate anions. In the present study, orthophosphates of zinc and calcium were exposed to high pressures on surfaces and in diamond anvil cells. An additional set of first-principles simulations was accomplished on ?-orthophosphate of zinc, which suggested that this material was already cross-linked before compression but that it nevertheless underwent a reversible coordination change under pressure in agreement with the experimental results presented here. Raman spectra indicate an irreversible, pressure-induced loss of long-range crystallinity. The pressures required to induce these changes are around 7 GPa for the zinc phosphates, while they are close to 21 GPa for the calcium phosphates. Hydrogenation of the metal phosphate lowers the threshold pressure by approximately 2-3 GPa in both cases. Moreover, ?-orthophosphate of zinc could be partially amorphisized under nonisotropic pressure on copper foils.

Shakhvorostov, Dmitry; Müser, Martin H.; Mosey, Nicholas J.; Munoz-Paniagua, David J.; Pereira, Gavin; Song, Yang; Kasrai, Masoud; Norton, Peter R.



Radiation-induced squamous sialometaplasia  

SciTech Connect

We describe a patient with recurrent acantholytic squamous cell carcinoma following radiation therapy. Mohs micrographic sections revealed extensive squamous sialometaplasia showing striking histologic similarity to the patient's squamous cell carcinoma. Criteria necessary to differentiate squamous sialometaplasia from neoplasm are presented. This differentiation is important to ensure adequate tumor resection without unnecessary sacrifice of tumor-free tissue.

Leshin, B.; White, W.L.; Koufman, J.A. (Wake Forest Univ., Winston-Salem, NC (USA))



Swift heavy ion induced crystalline-to-crystalline phase transition in zirconia and hafnia: a comparative study  

Microsoft Academic Search

Zirconia and hafnia are well-known isomorphic materials which share many physical and chemical properties but have also some differences. Regarding ion-beam induced effects, these features offer the interesting possibility to fix a lot of experimental parameters and to vary only a few ones. In this context, both oxides were irradiated with swift heavy ions and their structural evolution was monitored

Abdenacer Benyagoub




Microsoft Academic Search

Abstract--The radiation-induced decomposition,of biological resistant pollutants in drinking as well as in wastewater is briefly reviewed. First, some important units, definitions etc., radiation sources, as well as dose-depth curves in water as functions of the electron energy and 6°Co-y-rays are mentioned. Following is a schematical presentation of water radiolysis and of characteristics of primary,free radicals. Then the degradation,of some,aliphatic and

Nikola Getoff


Effect of the substrate-induced crystalline interphase on the adhesion of polyurethane to metals  

NASA Astrophysics Data System (ADS)

Bond strengths of three polyurethane to an aluminum were measured by indentation debonding, and interfacial features between two materials were microscopically investigated. All the polyurethanes crystallized at the Al substrate surface by heterogeneous nucleation, but the spherulitic features varied as a function of OH number. For non-aged samples, crosslinking level determined the adhesion of polyurethane film to aluminum substrate, while number density of spherulites was an important factor for aged samples. There was an optimum OH number to attain the highest bond strength. Hence, it was found that the decrease of OH number below this value, which is usually done by changing blowing gas from CFC-11 to pentane, caused poor adhesion of polyurethane foam to the aluminum. The crystalline interphase formed at the aluminum surface was examined by grazing incidence X-ray diffraction. The crystallinity of non-aged samples varied from air polymer surface to interface. The coherence lengths and interplanar spacings of all the reflections also changes up to interface by the presence of substrate. In particular, the integrated intensity of (100) and (021) reflections is linearly dependent upon X-ray penetration depth. The bond strength was exponentially proportional to the interfacial crystallinity, since stronger interface makes the adhesive force be double or redouble across interface. The preferred polymer molecular ordering in the 100 direction also provided stronger bonding of the polyurethane to the aluminum. From strain induced line broadening estimated by change of interplanar spacing, the polymer films possessing the greater dislocation density at interfacial area showed lower adhesion. It is believed that dislocations as stress concentrator play a part in determining adhesion. The rough zinc phosphated steel was used as a substrate with respect to a HCFC 141b and water co-blown polyurethane foam. Long period dissolution maintained interfacial crystallites, which were appeared by X-ray investigation. There was a complicated bond failure mode. The crystallites, found in the foamed region at the substrate surface, bridged the bulk foam and zinc phosphated substrate.

Kim, Jangsoon


Imaging radiation-induced normal tissue injury.  


Technological developments in radiation therapy and other cancer therapies have led to a progressive increase in five-year survival rates over the last few decades. Although acute effects have been largely minimized by both technical advances and medical interventions, late effects remain a concern. Indeed, the need to identify those individuals who will develop radiation-induced late effects, and to develop interventions to prevent or ameliorate these late effects is a critical area of radiobiology research. In the last two decades, preclinical studies have clearly established that late radiation injury can be prevented/ameliorated by pharmacological therapies aimed at modulating the cascade of events leading to the clinical expression of radiation-induced late effects. These insights have been accompanied by significant technological advances in imaging that are moving radiation oncology and normal tissue radiobiology from disciplines driven by anatomy and macrostructure to ones in which important quantitative functional, microstructural, and metabolic data can be noninvasively and serially determined. In the current article, we review use of positron emission tomography (PET), single photon emission tomography (SPECT), magnetic resonance (MR) imaging and MR spectroscopy to generate pathophysiological and functional data in the central nervous system, lung, and heart that offer the promise of, (1) identifying individuals who are at risk of developing radiation-induced late effects, and (2) monitoring the efficacy of interventions to prevent/ameliorate them. PMID:22348250

Robbins, Mike E; Brunso-Bechtold, Judy K; Peiffer, Ann M; Tsien, Christina I; Bailey, Janet E; Marks, Lawrence B



A report on radiation-induced gliomas  

SciTech Connect

Radiation-induced gliomas are uncommon, with only 73 cases on record to date. The disease that most frequently occasioned radiation therapy has been acute lymphoblastic leukemia (ALL). Three more cases are added here, two after irradiation for ALL and one after irradiation for tinea capitis. In a review of the relevant literature, the authors stress the possibility that the ALL-glioma and the retinoblastoma-glioma links point to syndromes in their own right that may occur without radiation therapy.56 references.

Salvati, M.; Artico, M.; Caruso, R.; Rocchi, G.; Orlando, E.R.; Nucci, F. (Univ. of Rome La Sapienza (Italy))



Radiation-induced effects in pyrochlores and nanoscale materials engineering  

NASA Astrophysics Data System (ADS)

Pyrochlore materials, A2B2O7, encompass a wide range of compositions and are technologically important for energy and environmental issues. For example, they may be used as ionic conductors in solid oxide fuel cells or nuclear waste forms for the storage of actinides, particularly Pu. Here, the recent progress in understanding ion beam irradiation-induced phenomena in pyrochlore compounds is briefly reviewed with a focus on the ion beam-induced crystalline-to-amorphous and pyrochlore-to-fluorite structural transitions. Systematic ion irradiation studies of lanthanide pyrochlores with B = Ti, Zr and Sn have indicated that the radiation response of the pyrochlore compounds is highly dependent on compositional changes. Both the ionic size and cation electronic configurations (e.g. bond-types) affect the structural distortion from the ideal fluorite structure and thus the response of pyrochlore-structure types to ion beam irradiation. An ion beam-induced pyrochlore-to-fluorite structural transition occurs in all irradiated pyrochlore compositions, and the independent kinetics of the cation and anion disordering processes has been discussed. Numerous novel nanostructures have been created by utilizing the ion beam-induced amorphization, order disorder transition and phase decomposition, such as amorphous and disordered nano-domains, perfectly lattice matched two-dimensional nanolayers, self-organized ripple structures, metallic nanoparticles and nanowires.

Lian, Jie; Weber, W. J.; Jiang, W.; Wang, L. M.; Boatner, L. A.; Ewing, R. C.



Lung fibrosis induced by crystalline silica particles is uncoupled from lung inflammation in NMRI mice.  


Previous studies in rats have suggested a causal relationship between progressive pulmonary inflammation and lung fibrosis induced by crystalline silica particles. We report here that, in NMRI mice, the lung response to silica particles is accompanied by a mild and non progressive pulmonary inflammation which is dispensable for the development of lung fibrosis. We found that glucocorticoid (dexamethasone) dramatically reduced lung injury, cellular inflammation and pro-inflammatory cytokine expression (TNF-?, IL-1? and KC) but had no significant effect on silica-induced lung fibrosis and expression of the fibrogenic and suppressive cytokines TGF-? and IL-10 in mice. Other anti-inflammatory molecules such as the COX inhibitor piroxicam or the phosphodiesterase 5 inhibitor sildenafil also reduced lung inflammation without modifying collagen, TGF-? or IL-10 lung content. Our findings indicate that the development of lung fibrosis in silica-treated NMRI mice is not driven by inflammatory lung responses and suggest that suppressive cytokines may represent critical fibrotic factors and potential therapeutic targets in silicosis. PMID:21414392

Rabolli, Virginie; Lo Re, Sandra; Uwambayinema, Francine; Yakoub, Yousof; Lison, Dominique; Huaux, François



Radiation-Induced Phase Transformations in Ilmenite-Group Minerals  

SciTech Connect

Transmission electron microscopy (TEM) is a powerful tool for characterizing and understanding radiation-induced structural changes in materials. We have irradiated single crystals of ilmenite (FeTiO{sub 3}) and geikielite (MgTiO{sub 3}) using ions and electrons to better understand the response of complex oxides to radiation. Ion irradiation experiments of bulk single crystals at 100 K show that ilmenite amorphized at doses of less than 1x10(exp15) Ar(2+)/sq cm and at a damage level in the peak damage region of 1 displacement per atom (dpa). Transmission electron microscopy and electron diffraction of a cross-sectioned portion of this crystal confirmed the formation of a 150 am thick amorphous layer. Geikielite proved to be more radiation resistant, requiring a flux of 2x10(exp 15) Xe(2+)/sq cm to induce amorphization at 100 K. This material did not amorphize at 470 K, despite a dose of 2.5 x10(exp 16) Xe(2+)/sq cm and a damage level as high as 25 dpa. Low temperature irradiations of electron- transparent crystals with 1 MeV Kr(+) also show that ilmenite amorphized after a damage level of 2.25 dpa at 175 K.Similar experiments on geikielite show that the microstructure is partially amorphous and partially crystalline after 10 dpa at 150 K. Concurrent ion and electron irradiation of both materials with 1 MeV Kr(+) and 0.9 MeV electrons produced dislocation loops in both materials, but no amorphous regions were formed. Differences in the radiation response of these isostructural oxides suggests that in systems with Mg-Fe solid solution, the Mg-rich compositions may be more resistant to structural changes.

Mitchell, J. N.



Radiation-induced intestinal pseudoobstruction  

SciTech Connect

A case of intestinal pseudoobstruction occurring 30 yr after radiation therapy is described. Mechanical causes of obstruction were excluded by laparotomy. Histology of full-thickness sections of the small bowel revealed vascular ectasia and sclerosis, serosal fibrosis, neuronal proliferation within the submucosa, and degeneration of the muscle fibers of the circular layer of the muscularis propria. On the basis of the clinical and histologic findings we conclude that, in this patient, intestinal pseudoobstruction was due to muscular and neuronal injury from abdominal irradiation.

Perino, L.E.; Schuffler, M.D.; Mehta, S.J.; Everson, G.T.



Radiation-induced clastogenic plasma factors  

Microsoft Academic Search

Ionizing irradiation induces chromosomal aberrations in directly exposed cells and is known to have mutagenic and carcinogenic potential for the exposed host. Under controlled conditions, we examined whether such clastogenic effects of irradiation might be due in part to radiation-induced plasma factors. Irradiated cells and sera from CF-Nelson rats were used at 15 min, and 1, 7, 14, and 56-70

G. B. Faguet; S. M. Reichard; D. A. Welter



Radiation-induced neuropathy in cancer survivors.  


Radiation-induced peripheral neuropathy is a chronic handicap, frightening because progressive and usually irreversible, usually appearing several years after radiotherapy. Its occurrence is rare but increasing with improved long-term cancer survival. The pathophysiological mechanisms are not yet fully understood. Nerve compression by indirect extensive radiation-induced fibrosis plays a central role, in addition to direct injury to nerves through axonal damage and demyelination and injury to blood vessels by ischaemia following capillary network failure. There is great clinical heterogeneity in neurological presentation since various anatomic sites are irradiated. The well-known frequent form is radiation-induced brachial plexopathy (RIBP) following breast cancer irradiation, while tumour recurrence is easier to discount today with the help of magnetic resonance imaging and positron emission tomography. RIBP incidence is in accordance with the irradiation technique, and ranges from 66% RIBP with 60Gy in 5Gy fractions in the 1960s to less than 1% with 50Gy in 2Gy fractions today. Whereas a link with previous radiotherapy is forgotten or difficult to establish, this has recently been facilitated by a posteriori conformal radiotherapy with 3D-dosimetric reconstitution: lumbosacral radiculo-plexopathy following testicular seminoma or Hodgkin's disease misdiagnosed as amyotrophic lateral sclerosis. Promising treatments via the antioxidant pathway for radiation-induced fibrosis suggest a way to improve the everyday quality of life of these long-term cancer survivors. PMID:23245644

Delanian, Sylvie; Lefaix, Jean-Louis; Pradat, Pierre-François



Cataracts induced by microwave and ionizing radiation  

SciTech Connect

Microwaves most commonly cause anterior and/or posterior subcapsular lenticular opacities in experimental animals and, as shown in epidemiologic studies and case reports, in human subjects. The formation of cataracts seems to be related directly to the power of the microwave and the duration of exposure. The mechanism of cataractogenesis includes deformation of heat-labile enzymes, such as glutathione peroxide, that ordinarily protect lens cell proteins and membrane lipids from oxidative damage. Oxidation of protein sulfhydryl groups and the formation of high-molecular-weight aggregates cause local variations in the orderly structure of the lens cells. An alternative mechanism is thermoelastic expansion through which pressure waves in the aqueous humor cause direct physical damage to the lens cells. Cataracts induced by ionizing radiation (e.g., X-rays and gamma rays) usually are observed in the posterior region of the lens, often in the form of a posterior subcapsular cataract. Increasing the dose of ionizing radiation causes increasing opacification of the lens, which appears after a decreasing latency period. Like cataract formation by microwaves, cataractogenesis induced by ionizing radiation is associated with damage to the lens cell membrane. Another possible mechanism is damage to lens cell DNA, with decreases in the production of protective enzymes and in sulfur-sulfur bond formation, and with altered protein concentrations. Until further definitive conclusions about the mechanisms of microwaves and ionizing radiation induced cataracts are reached, and alternative protective measures are found, one can only recommend mechanical shielding from these radiations to minimize the possibility of development of radiation-induced cataracts. 74 references.

Lipman, R.M.; Tripathi, B.J.; Tripathi, R.C.



Ultrafast sub-threshold photo-induced response in crystalline and amorphous GeSbTe thin films  

NASA Astrophysics Data System (ADS)

Pump-probe optical reflectivity and terahertz transmission measurements have been used to investigate time resolved sub-threshold photo-induced effects in crystalline and amorphous GeSbTe films at MHz repetition rates. The reflectivity in both phases exhibits long-lived modulations consistent with the sign of the changes that occur upon switching but of smaller magnitude. These can be understood by the generation of acoustic strains with the crystalline phase response dominated by thermal effects and the amorphous phase response associated with electronically induced changes. Evidence for a photo-induced distortion is observed in the amorphous phase which develops homogeneously within the excited region on few-picosecond time scales.

Shu, M. J.; Chatzakis, I.; Kuo, Y.; Zalden, P.; Lindenberg, A. M.



Radiation-induced neuroinflammation and radiation somnolence syndrome.  


Cranial irradiation remains a standard treatment for malignant and benign brain diseases. Although this procedure helps to lengthen the life expectancy of the patient, the appearance of adverse effects related to radiation-induced injury is inevitable. Radiation somnolence syndrome (RSS) has been described as a delayed effect observed mainly after whole-brain radiotherapy in children. The RSS was first linked to demyelination, but more recently it has been proposed that the inflammatory response plays a primary role in the aforementioned syndrome. To evaluate the feasibility of this hypothesis, we explored previous work about RSS and reviewed published research that included measurements of the inflammatory response in models of brain exposure to ionizing radiation. Pro-inflammatory cytokines such as interleukin-1?, tumor necrosis factor-?, interleukin-6 and interleukin-18 as well as other inflammatory markers such as cyclooxygenase-2, prostaglandin E?, glial fibrillary acid protein, intercellular adhesion molecule-1 and nuclear factor-?B appear to be involved in the brain's response to radiation. However, certain publications have described the somnogenic effects of these cytokines and inflammatory markers. Although the radiation response is a complex phenomenon that involves several molecular and cellular processes, we propose that inflammation may be closely related to the adverse effects of brain irradiation and therefore to the etiology of RSS. PMID:22998139

Ballesteros-Zebadúa, Paola; Chavarria, Anahi; Celis, Miguel Angel; Paz, Carlos; Franco-Pérez, Javier



p47phox Deficiency Induces Macrophage Dysfunction Resulting in Progressive Crystalline Macrophage Pneumonia  

PubMed Central

Nicotinamide dinucleotide phosphate oxidase-deficient (p47phox?/?) mice are a model of human chronic granulomatous disease; these mice are prone to develop systemic infections and inflammatory diseases. The use of antibiotic (Bactrim) prophylaxis in a specific pathogen-free environment, however, impedes infection in the majority of p47phox?/? mice. We examined infection-free p47phox?/? mice between 1 and 14 months of age and found that they developed proliferative macrophage lesions containing Ym1/Ym2 protein and crystals in lung, bone marrow, lymph nodes, and spleen. Here, we show that the lung lesions progressed from single macrophages with intracellular Ym1/Ym2 protein crystals to severe diffuse crystalline macrophage pneumonia without histological evidence of either granulation tissue or pulmonary fibrosis. Ym1/Ym2 is a chitinase-like secretory protein that is transiently induced in alternatively activated macrophages during T-helper (Th)2-biased pathogenesis and during chemical and traumatic inflammation. Bronchoalveolar lavage from p47phox?/? mice contained significantly higher levels of Th-1 (interferon-?), Th-2 (interleukin-4), and Th-17 (interleukin-17)-associated cytokines than wild-type mice, as well as copious amounts of interleukin-12, indicating that Ym1-secreting p47phox?/? macrophages are also integrated into classically activated macrophage responses. These results suggest that p47phox?/? macrophages are extremely pliable, due in part to an intrinsic dysfunction of macrophage activation pathways that allows for distinct classical or alternative activation phenotypes.

Liu, Qi; Cheng, Lily I.; Yi, Liang; Zhu, Nannan; Wood, Adam; Changpriroa, Cattlena May; Ward, Jerrold M.; Jackson, Sharon H.



Radiation-induced brain injury: A review  

PubMed Central

Approximately 100,000 primary and metastatic brain tumor patients/year in the US survive long enough (>6 months) to experience radiation-induced brain injury. Prior to 1970, the human brain was thought to be highly radioresistant; the acute CNS syndrome occurs after single doses >30 Gy; white matter necrosis occurs at fractionated doses >60 Gy. Although white matter necrosis is uncommon with modern techniques, functional deficits, including progressive impairments in memory, attention, and executive function have become important, because they have profound effects on quality of life. Preclinical studies have provided valuable insights into the pathogenesis of radiation-induced cognitive impairment. Given its central role in memory and neurogenesis, the majority of these studies have focused on the hippocampus. Irradiating pediatric and young adult rodent brains leads to several hippocampal changes including neuroinflammation and a marked reduction in neurogenesis. These data have been interpreted to suggest that shielding the hippocampus will prevent clinical radiation-induced cognitive impairment. However, this interpretation may be overly simplistic. Studies using older rodents, that more closely match the adult human brain tumor population, indicate that, unlike pediatric and young adult rats, older rats fail to show a radiation-induced decrease in neurogenesis or a loss of mature neurons. Nevertheless, older rats still exhibit cognitive impairment. This occurs in the absence of demyelination and/or white matter necrosis similar to what is observed clinically, suggesting that more subtle molecular, cellular and/or microanatomic modifications are involved in this radiation-induced brain injury. Given that radiation-induced cognitive impairment likely reflects damage to both hippocampal- and non-hippocampal-dependent domains, there is a critical need to investigate the microanatomic and functional effects of radiation in various brain regions as well as their integration at clinically relevant doses and schedules. Recently developed techniques in neuroscience and neuroimaging provide not only an opportunity to accomplish this, but they also offer the opportunity to identify new biomarkers and new targets for interventions to prevent or ameliorate these late effects.

Greene-Schloesser, Dana; Robbins, Mike E.; Peiffer, Ann M.; Shaw, Edward G.; Wheeler, Kenneth T.; Chan, Michael D.



Generation of high-amplitude soliton waves in crystalline materials of different dimensions under high radiative, dynamic, and temperature loads  

NASA Astrophysics Data System (ADS)

It is shown that beams of high-amplitude supersonic breather solitons, phonons, and subsonic excitations of new type (torsions) are generated in crystalline materials of different dimensions under high radiative and dynamic loads near the stability threshold. The dispersion dependences of solitons and phonons in 1D crystals are presented. It is shown that, in 2D crystals beams consisting of six or two (depending on the bombarding particle direction), breather solitons are generated and propagate in certain crystallographic directions. The masses of soliton excitations as particles (coupled complexes of massless phonons) have been determined. It is shown that the subsonic soliton waves of a new type with torsion atomic vibrations are generated in 3D nanotubes, along with supersonic soliton waves of longitudinal vibrations.

Dubovsky, O. A.; Orlov, A. V.



Generation of high-amplitude soliton waves in crystalline materials of different dimensions under high radiative, dynamic, and temperature loads  

SciTech Connect

It is shown that beams of high-amplitude supersonic breather solitons, phonons, and subsonic excitations of new type (torsions) are generated in crystalline materials of different dimensions under high radiative and dynamic loads near the stability threshold. The dispersion dependences of solitons and phonons in 1D crystals are presented. It is shown that, in 2D crystals beams consisting of six or two (depending on the bombarding particle direction), breather solitons are generated and propagate in certain crystallographic directions. The masses of soliton excitations as particles (coupled complexes of massless phonons) have been determined. It is shown that the subsonic soliton waves of a new type with torsion atomic vibrations are generated in 3D nanotubes, along with supersonic soliton waves of longitudinal vibrations.

Dubovsky, O. A., E-mail:; Orlov, A. V. [Leipunsky Institute for Physics and Power Engineering, State Scientific Center of the Russian Federation (Russian Federation)



Amorphous silicon/crystalline silicon heterojunctions for nuclear radiation detector applications  

SciTech Connect

Results on characterization of electrical properties of amorphous Si films for the 3 different growth methods (RF sputtering, PECVD [plasma enhanced], LPCVD [low pressure]) are reported. Performance of these a-Si films as heterojunctions on high resistivity p-type and n- type crystalline Si is examined by measuring the noise, leakage current, and the alpha particle response of 5mm dia detector structures. It is demonstrated that heterojunction detectors formed by RF sputtered films and PECVD films are comparable in performance with conventional surface barrier detectors. Results indicate that the a-Si/c-Si heterojunctions have the potential to greatly simplify detector fabrication. Directions for future avenues of nuclear particle detector development are indicated.

Walton, J.T.; Hong, W.S.; Luke, P.N.; Wang, N.W. [Lawrence Berkeley National Lab., CA (United States); Ziemba, F.P. [Quantrad Sensor, Inc., Santa Clara, CA (United States)



Electrical current-induced gradual failure of crystalline Ge2Sb2Te5 for phase-change memory  

NASA Astrophysics Data System (ADS)

Electrical failure in crystalline Ge2Sb2Te5 was observed under a direct current bias, which induces a steady degradation of the electrical conductivity. This failure is induced by electromigration because alternating current bias stressing does not trigger this behavior. Nano-scaled voids were generated during current stressing, which explains the gradual increase in the quantitative resistance. Each nano-void previously comprised a molten phase that was induced by localized melting, which produced compositional variation during the solidification process. The phase-change memory can be damaged by electrical stressing in the non-active regions.

Park, Yong-Jin; Yang, Tae-Youl; Cho, Ju-Young; Lee, So-Yeon; Joo, Young-Chang



Ionizing Radiation-induced Diseases in Korea  

PubMed Central

Radiation risk has become well known through epidemiological studies of clinically or occupationally exposed populations, animal experiments, and in vitro studies; however, the study of radiation related or induced disease has been limited in Korea. This study is to find the level of occupational radiation exposure for various kinds of accidents, compensated occupational diseases, related studies, and estimations on future occupational disease risks. Research data of related institutions were additionally investigated. About 67% of 62,553 radiation workers had no exposure or less than 1.2 mSv per year. The 5 reported cases on radiation accident patients in Korea occurred during nondestructive testing. According to the recent rapid increase in the number of workers exposed to radiation, a higher social recognition of cancer, and an increasing cancer mortality rate, it is expected that occupational disease compensation will rapidly increase as well. Therefore, it is important to develop scientific and objective decision methods, such as probability of causation and screening dose in the establishment of an exposure and health surveillance system.

Jeong, Meeseon; Moon, Kieun; Jo, Min-Heui; Kang, Seong-Kyu



Evaluation of electromagnetic radiated susceptibility testing using induced currents  

Microsoft Academic Search

This paper uses electromagnetic field theory to examine the relations between radiated induced currents and Bulk Current Injection (BCI) injected currents to compare the data from the BCI and radiated field induced currents and to determine the range where BCI effectively simulates the radiated induced coupling. Establishing a uniform plane wave to illuminate the cables is also addressed. The test

Dawn H. Trout; N. F. Audeh



Acceptor-donor-acceptor-based small molecules with varied crystallinity: processing additive-induced nanofibril in blend film for photovoltaic applications.  


A series of acceptor-donor-acceptor-based small molecules (SMs) with varied crystallinity were successfully synthesized. The processing additive can induce the SMs to self-organize as nanofibrils with higher crystallinity and controlled scales of nanofibrils, which have significant influence on the photovoltaic performance. PMID:23986227

Li, Chao; Chen, Yujin; Zhao, Yue; Wang, Huifang; Zhang, Wei; Li, Yaowen; Yang, Xiaoming; Ma, Changqi; Chen, Liwei; Zhu, Xiulin; Tu, Yingfeng



Role of neurotensin in radiation-induced hypothermia in rats  

SciTech Connect

The role of neurotensin in radiation-induced hypothermia was examined. Intracerebroventricular (ICV) administration of neurotensin produced dose-dependent hypothermia. Histamine appears to mediate neurotensin-induced hypothermia because the mast cell stabilizer disodium cromoglycate and antihistamines blocked the hypothermic effects of neurotensin. An ICV pretreatment with neurotensin antibody attenuated neurotensin-induced hypothermia, but did not attenuate radiation-induced hypothermia, suggesting that radiation-induced hypothermia was not mediated by neurotensin.

Kandasamy, S.B.; Hunt, W.A.; Harris, A.H. (Armed Forces Radiobiology Research Institute, Bethesda, MD (USA))



Radiation-induced cell death mechanisms  

Microsoft Academic Search

The main goal when treating malignancies with radiation therapy is to deprive tumor cells of their reproductive potential.\\u000a One approach to achieve this is by inducing tumor cell apoptosis. Accumulating evidences suggest that induction of apoptosis\\u000a alone is insufficient to account for the therapeutic effect of radiotherapy. It has become obvious in the last few years that\\u000a inhibition of the

David Eriksson; Torgny Stigbrand



Influence of interface on radiation effects of crystalline polymer—radiation effects on polyamide-1010 containing BMI  

Microsoft Academic Search

Aimed at saving the radiation dose required to crosslinking the polyamide-1010, BMI\\/PA1010 systems containing different amounts of difunctional crosslinking agent N,N?-bis-maleimide-4,4?-biphenyl methane (BMI) were prepared and the structure changes at the crystallographic and supermolecular levels before and after irradiation were studied by using WAXD, SAXS, and DSC techniques. It was found that by incorporation of BMI the microcrystal size L100

L. Zhang; H. Zhang; D. Chen



Pattern of liquid crystalline droplets induced by two beam interference in azobenzene derivative  

NASA Astrophysics Data System (ADS)

A pattern of liquid crystalline droplets dispersed in the isotropic liquid can be formed during illumination by two interfering laser beams in certain range of the temperature and the light intensity. Azobenzene derivative substituted by long alkyl and alkoxy chains exhibiting smectic phases has been used for the study. The pattern can be reversibly erased and rewritten by shutting down and opening of the interfering beams. Polarized microscope images have shown the formation of numerous liquid crystalline droplets at bright regions of the interference fringes. Influence of the temperature and the light intensity has been studied by measuring the diffraction efficiency dynamics. Photothermal and photoorientational mechanisms of the formation of liquid crystalline droplets pattern have been proposed and discussed.

Czajkowski, Maciej; Dradrach, Klaudia; Bartkiewicz, Stanislaw; Galewski, Zbigniew



Radiation induced genomic instability in bystander cells  

NASA Astrophysics Data System (ADS)

There is considerable evidence that exposure to ionizing radiation may induce a heritable genomic instability that leads to a persisting increased frequency of genetic and functional changes in the non-irradiated progeny of a wide variety of irradiated cells Genomic instability is measured as delayed expressions in chromosomal alterations micronucleus formation gene mutations and decreased plating efficiency During the last decade numerous studies have shown that radiation could induce bystander effect in non-irradiated neighboring cells similar endpoints have also been used in genomic instability studies Both genomic instability and the bystander effect are phenomena that result in a paradigm shift in our understanding of radiation biology In the past it seemed reasonable to assume that the production of single- and double-strand DNA breaks are due to direct energy deposition of energy by a charged particle to the nucleus It turns out that biology is not quite that simple Using the Columbia University charged particle microbeam and the highly sensitive human hamster hybrid AL cell mutagenic assay we irradiated 10 of the cells with a lethal dose of 30 alpha particles through the nucleus After overnight incubation the remaining viable bystander cells were replated in dishes for colony formation Clonal isolates were expanded and cultured for 6 consecutive weeks to assess plating efficiency and mutation frequency Preliminary results indicated that there was no significant decrease in plating efficiency among the bystander colonies when compared with

Zhou, H.; Gu, S.; Randers-Pehrson, G.; Hei, T.


Spatial distribution of radiation damage to crystalline proteins at 25-300 K.  


The spatial distribution of radiation damage (assayed by increases in atomic B factors) to thaumatin and urease crystals at temperatures ranging from 25 to 300 K is reported. The nature of the damage changes dramatically at approximately 180 K. Above this temperature the role of solvent diffusion is apparent in thaumatin crystals, as solvent-exposed turns and loops are especially sensitive. In urease, a flap covering the active site is the most sensitive part of the molecule and nearby loops show enhanced sensitivity. Below 180 K sensitivity is correlated with poor local packing, especially in thaumatin. At all temperatures, the component of the damage that is spatially uniform within the unit cell accounts for more than half of the total increase in the atomic B factors and correlates with changes in mosaicity. This component may arise from lattice-level, rather than local, disorder. The effects of primary structure on radiation sensitivity are small compared with those of tertiary structure, local packing, solvent accessibility and crystal contacts. PMID:22948911

Warkentin, Matthew; Badeau, Ryan; Hopkins, Jesse B; Thorne, Robert E



Pressure-Induced Concurrent Transformation to an Amorphous and Crystalline Phase in Berlinite-Type FePO{sub 4}  

SciTech Connect

X-ray diffraction, Raman scattering, and M{umlt o}ssbauer spectroscopy provide a diverse description of the high pressure behavior of berlinite-type FePO{sub 4} . At a pressure of 2.5(5) GPa, a transformation to a coexisting new crystalline (chp) and amorphous (ahp) phase is observed with about equal abundance. The chp phase is identified as a VCrO{sub 4} type, where Fe{sup III } and P{sup V} ions, respectively, are sixfold and fourfold coordinated. In the 6{endash}25GPa range and after decompression, the relative abundance of the chp and ahp phases remains unchanged. These phenomena of concurrent amorphous and crystalline transformations at low hydrostatic pressure and stable abundance ratio over a large pressure range are unique in pressure-induced structural transformations of SiO{sub 2} analogs. {copyright} {ital 1997} {ital The American Physical Society}

Pasternak, M.P.; Rozenberg, G.K.; Milner, A.P.; Amanowicz, M. [School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv (Israel); Zhou, T.; Schwarz, U.; Syassen, K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Dean Taylor, R. [Los Alamos National Laboratory, MST10, Los Alamos, New Mexico 87545 (United States); Hanfland, M. [ESRF, BP220, F-38043 Grenoble (France); Brister, K. [CHESS, Wilson Laboratory, Cornell University, Ithaca, New York 14853 (United States)



Effect on thickness of Al layer in poly-crystalline Si thin films using aluminum(Al) induced crystallization method.  


The polycrystalline silicon (poly-Si) thin films were prepared by aluminum induced crystallization. Aluminum (Al) and amorphous silicon (a-Si) layers were deposited using DC sputtering and plasma enhanced chemical vapor deposition method, respectively. For the whole process Al properties of bi-layers can be one of the important factors. In this paper we investigated the structural and electrical properties of poly-crystalline Si thin films with a variation of Al thickness through simple annealing process. All samples showed the polycrystalline phase corresponding to (111), (311) and (400) orientation. Process time, defined as the time required to reach 95% of crystalline fraction, was within 60 min and Al(200 nm)/a-Si(400 nm) structure of bi-layer showed the fast response for the poly-Si films. The conditions with a variation of Al thickness were executed in preparing the continuous poly-Si films for solar cell application. PMID:21456186

Jeong, Chaehwan; Na, Hyeon Sik; Lee, Suk Ho



Magnetic-field-induced enhancement of crystallinity and field-effect mobilities in phthalocyanine thin films  

NASA Astrophysics Data System (ADS)

Organic semiconductor thin films were fabricated by thermal deposition of free-base and metal phthalocyanines under a static magnetic field. A vertical magnetic field enhanced the crystallinity of the edge-on orientation of the phthalocyanine discs, whereas a horizontal magnetic field had a minimal effect on the crystallinity. The major factor for the orientation change is attributed to the diamagnetic anisotropies of ?-electrons in the phthalocyanine macrocycles. Field-effect transistors of phthalocyanine films fabricated under a vertical magnetic field exhibited better hole mobilities and on-current values with smaller threshold voltages than those of phthalocyanine films fabricated without a magnetic field.

Tabata, Kenichi; Sasaki, Takayuki; Yamamoto, Yohei



Ionizing Radiation Induces Delayed Hyperrecombination in Mammalian Cells  

Microsoft Academic Search

Exposure to ionizing radiation can result in delayed effects that can be detected in the progeny of an irradiated cell multiple generations after the initial exposure. These effects are described under the rubric of radiation-induced genomic instability and encompass multiple genotoxic endpoints. We have developed a green fluorescence protein (GFP)-based assay and demonstrated that ionizing radiation induces genomic instability in

Lei Huang; Suzanne Grim; Leslie E. Smith; Perry M. Kim; Jac A. Nickoloff; Olga G. Goloubeva; William F. Morgan



Radiation-induced osteosarcoma of the sphenoid bone  

SciTech Connect

The case of a patient who developed osteosarcoma in the sphenoid bone 15 years after radiation therapy for a craniopharyngioma is reported. Radiation-induced osteosarcoma of the sphenoid bone has not been reported previously. Reported cases of radiation-induced osteosarcomas are reviewed.

Tanaka, S.; Nishio, S.; Morioka, T.; Fukui, M.; Kitamura, K.; Hikita, K. (Kyushui Univ., Fukuoka (Japan))



Management of radiation-induced rectal bleeding.  


Pelvic radiation disease is one of the major complication after radiotherapy for pelvic cancers. The most commonly reported symptom is rectal bleeding which affects patients' quality of life. Therapeutic strategies for rectal bleeding are generally ignored and include medical, endoscopic, and hyperbaric oxygen treatments. Most cases of radiation-induced bleeding are mild and self-limiting, and treatment is normally not indicated. In cases of clinically significant bleeding (i.e. anaemia), medical therapies, including stool softeners, sucralfate enemas, and metronidazole, should be considered as first-line treatment options. In cases of failure, endoscopic therapy, mainly represented by argon plasma coagulation and hyperbaric oxygen treatments, are valid and complementary second-line treatment strategies. Although current treatment options are not always supported by high-quality studies, patients should be reassured that treatment options exist and success is achieved in most cases if the patient is referred to a dedicated centre. PMID:24101202

Laterza, Liboria; Cecinato, Paolo; Guido, Alessandra; Mussetto, Alessandro; Fuccio, Lorenzo



Radiation induced carcinoma of the larynx  

SciTech Connect

A squamous cell carcinoma presented in a 20 year old female nonsmoker three years after receiving a high dosage of radiation therapy to the base of the skull, face and entire neuroaxis and intense combination chemotherapy for a parameningeal rhabdomyosarcoma of the paranasal sinuses is reported. The larynx received a dose of about 3,500 rads over an eight week period. This dosage in conjunction with the associated intense chemotherapy regimen given to the patient may explain the appearance of a radiation induced tumor in an unusually short latent period. This certainly represents a risk in young patients in whom an aggressive combined approach is taken and the physician should be aware of.

Amendola, B.E.; Amendola, M.A.; McClatchey, K.D.



Radiation-induced electron migration along DNA  

SciTech Connect

Radiation-induced electron migration along DNA is a mechanism by which randomly produced stochastic energy deposition events can lead to nonrandom types of damage along DNA manifested distal to the sites of the initial energy deposition. Electron migration along DNA is significantly influenced by the DNA base sequence and DNA conformation. Migration along 7 base pairs in oligonucleotides containing guanine bases was observed for oligonucleotides irradiated in solution which compares to average migration distances of 6 to 10 bases for Escherichia coli DNA irradiated in solution and 5.5 base pairs for Escherichia coli DNA irradiated in cells. Evidence also suggests that electron migration can occur preferentially in the 5{prime} to 3{prime} direction along DNA. Our continued efforts will provide information regarding the contribution of electron transfer along DNA to formation of locally multiply damaged sites created in DNA by exposure to ionizing radiation.

Fuciarelli, A.F.; Sisk, E.C.; Miller, J.H. [Pacific Northwest Lab., Richland, WA (United States); Zimbrick, J.D. [National Research Council, Washington, DC (United States)



Possible Repair of Radiation-Induced Nondisjunction in Mouse Oocytes  

Microsoft Academic Search

There are some data from human epidemiological studies which suggest that radiation has a small but significant effect in causing aneuploid gametes. Alberman et al. (1972) suggested that much of this radiation occurred more than ten years before the conception of the abnormal child. Mice have been used to study experimentally radiation effects on chromosome segregation. Radiation induces nondisjunction in

Barbara Gayle Brennan



Possible repair of radiation-induced nondisjunction in mouse oocytes  

Microsoft Academic Search

There are some data human epidemiological studies which suggest that radiation has a small but significant effect in causing aneuploid gametes. Alberman et al. (1972) suggested that much of this radiation occurred more than ten years before the conception of the abnormal child. Mice have been used to study experimentally radiation effects on chromosome segregation. Radiation induces nondisjunction in several

Barbara Gayle Brennan



Prediction of Charge-Induced Molecular Alignment of Biomolecules Dissolved in Dilute Liquid-Crystalline Phases  

Microsoft Academic Search

Alignment of macromolecules in nearly neutral aqueous lyotropic liquid-crystalline media such as bicelles, commonly used in macromolecular NMR studies, can be predicted accurately by a steric obstruction model (Zweckstetter and Bax, 2000). A simple extension of this model is described that results in improved predictions for both the alignment orientation and magnitude of protein and DNA solutes in charged nematic

Markus Zweckstetter; Gerhard Hummer; Ad Bax



?-B- and ?-A-Crystallin Prevent Irreversible Acidification-Induced Protein Denaturation  

Microsoft Academic Search

?-Crystallin (?), a major structural protein of the mammalian lens, is a large, physically heterogeneous macromolecule with an average molecular weight of approximately 800 kDa and is composed of two 20-kDa polypeptides designated as ?A and ?B. A line of evidence strongly suggests that ?B may have an essential nonlenticular function. Here it is demonstrated that ?B can bind partially

Keyang Wang



Radiation-induced injury of the esophagus  

SciTech Connect

Forty patients with functional or morphologic esophageal abnormalities following radiotherapy were identified. Abnormalities included abnormal motility with and without mucosal edema, stricture, ulceration and pseudodiverticulum, and fistula. Abnormal motility occurred 4 to 12 weeks following radiotherapy alone and as early as 1 week after therapy when concomitant chemotherapy had been given. Strictures developed 4 to 8 months following completion of radiotherapy. Ulceration, pseudodiverticulum, and fistula formation did not develop in a uniform time frame. Radiation-induced esophageal injury is more frequent when radiotherapy and chemotherapy are combined than it is with radiotherapy alone.

Lepke, R.A.; Libshitz, H.I.



Radiative recombination mechanisms in individual wurtzite ZnSe nanowires with a defect-free single-crystalline microstructure  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) spectroscopy performed on arrays of semiconductor nanowires (NWs) suffers from ensemble broadening of PL lines, and fails to separate the PL from NWs of different crystal structures in the ensemble. Even the results on PL from single NWs are not devoid of ambiguity. This is because the influence of structural defects in NWs, such as stacking faults, twin boundaries and dislocations, on their optical spectra cannot be accounted for since the structural characteristics of the same NW remain largely unknown. We performed low-temperature PL spectroscopy on individual wurtzite (WZ) ZnSe NWs, and confirmed a homogeneous single-crystalline microstructure without any extended defects in these NWs, thus excluding any role of structural imperfections in their optical spectra. The luminescence is shown to be dominated solely by native point defects, while no role of extrinsic impurities was found. The radiative recombination is shown to originate from excitons bound to vacancies of Zn (VZn), VZn-complexes, and their phonon replicas. The binding energies of the acceptor-bound excitons, ionization energies of the acceptors, and average number of phonons emitted for shallow donor-VZn acceptor pair related transition were determined. Distinct from previous studies on PL from arrays of ZnSe NWs, this work provides an unambiguous interpretation of the PL spectra and assignment of PL peaks to WZ ZnSe. Narrow excitonic emission of linewidths 2.9 meV indicate excellent optical quality of WZ ZnSe NWs.

Saxena, Ankur; Pan, Qi; Ruda, Harry E.



Radiative recombination mechanisms in individual wurtzite ZnSe nanowires with a defect-free single-crystalline microstructure.  


Photoluminescence (PL) spectroscopy performed on arrays of semiconductor nanowires (NWs) suffers from ensemble broadening of PL lines, and fails to separate the PL from NWs of different crystal structures in the ensemble. Even the results on PL from single NWs are not devoid of ambiguity. This is because the influence of structural defects in NWs, such as stacking faults, twin boundaries and dislocations, on their optical spectra cannot be accounted for since the structural characteristics of the same NW remain largely unknown. We performed low-temperature PL spectroscopy on individual wurtzite (WZ) ZnSe NWs, and confirmed a homogeneous single-crystalline microstructure without any extended defects in these NWs, thus excluding any role of structural imperfections in their optical spectra. The luminescence is shown to be dominated solely by native point defects, while no role of extrinsic impurities was found. The radiative recombination is shown to originate from excitons bound to vacancies of Zn (VZn), VZn-complexes, and their phonon replicas. The binding energies of the acceptor-bound excitons, ionization energies of the acceptors, and average number of phonons emitted for shallow donor-VZn acceptor pair related transition were determined. Distinct from previous studies on PL from arrays of ZnSe NWs, this work provides an unambiguous interpretation of the PL spectra and assignment of PL peaks to WZ ZnSe. Narrow excitonic emission of linewidths 2.9 meV indicate excellent optical quality of WZ ZnSe NWs. PMID:23446447

Saxena, Ankur; Pan, Qi; Ruda, Harry E



Radiation Induced Bystander Effects in Human Lymphoblastoid Cells.  

National Technical Information Service (NTIS)

It is well accepted that cells, in response to radiation, may release transmissible factors. These transmissible factors, clastogenic factors, have been reported to induce genomic instability in cells that have not been directly exposed to radiation. We h...

T. M. Segura D. Wilkinson L. Prud'honne-Lalonde E. M. Thorleifson S. Lachapelle



Overview of Radiation-Induced Interface Traps in MOS Structures  

National Technical Information Service (NTIS)

We focus on radiation-induced interface traps, describing first how they fit into the overall radiation response of metal-oxide semiconductor (MOS) structures. Detailed measurements of the time-, field-, and temperature-dependences of the buildup of radia...

F. B. McLean H. E. Boesch J. M. McGarrity T. R. Oldham



Radiation induced micrencephaly in guinea pigs  

SciTech Connect

A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely related to the small difference in doses and the limited numbers of animals examined. There are several factors that can influence the brain weight of guinea pig pups, such as caging and housing conditions, the sex of the animal, and litter size. These should be taken into account for accurate analysis. Dam weight did not appear to have a significant effect. The confirmation of a micrencephalic effect induced x rays at doses of 75-mGy during this late embryonic stage of development is consistent with the findings of small head size induced in those exposed prior to the eight week of conception at Hiroshima. This implies a mechanism for micrencephaly different from those previously suggested and lends credence to a causal relation between radiation and small head size in humans at low doses as reported by Miller and Mulvihill. 16 refs., 13 tabs.

Wagner, L.K.; Johnston, D.A.; Felleman, D.J.



[Search for chaperon-like anticataract drugs, the antiaggregants of lens crystallins. Communication. 1. Chaperon-like activity of N-acetyl carnosine dipeptide: in vitro study on a model of ultraviolet-induced aggregation of betaL-crystallin].  


Aggregation ofcrystallins, the lens proteins, is one of the basic stages of cataract formation. Among the protein aggregation models used to study the molecular mechanisms of the initial stages of lenticular opacity, UV-induced aggregation of betaL-crystallin is most close to the in vivo conditions. The carnosine derivative N-acetyl carnosine has been shown to be effective in inhibiting the UV-induced aggregation of betaL-crystallin. Examination of the accumulation kinetics of carbonyl groups in betaL-crystallin under UV irradiation has indicated that neither carnosine nor N-acetyl carnosine fails to affect this parameter--an indicator of oxidative protein damage. By taking into account also the fact that N-acetyl carnosine is not an antioxidant, it can be believed that the molecular mechanism of action of this compound on UV-induced aggregation of betaL is unassociated with its antioxidative properties. The authors hypothesize that the molecular chaperon-like properties similar to those of alpha-crystallin underlie the mechanism of action of the acetyl derivative carnosine. The prospects for searching anticataract agents of a new chaperon-like class are discussed. PMID:18488459

Muranov, K O; Dizhevskaia, A K; Boldyrev, A A; Karpova, O E; Sheremet, N L; Polunin, G S; Avetisov, S E; Ostrovski?, M A


Radiation-induced intracranial meningioma and multiple cavernomas.  


Brain irradiation has several well-known long-term side effects, including radiation-induced neoplasms and vasculopathy. In this case report, we describe an extremely rare case of meningioma and 15 cavernomas developing in a 29-year-old man, 19 years after cranial irradiation for posterior cranial fossa medulloblastoma. To our knowledge, this is the first case of a radiation-induced meningioma accompanied by this many radiation-induced cavernous angiomas. PMID:24051144

Chourmouzi, Danai; Papadopoulou, Elissavet; Kontopoulos, Athanasios; Drevelegas, Antonios



YAG laser-induced crystalline dot patterning in samarium tellurite glasses  

Microsoft Academic Search

A CW YAG laser with a wavelength of 1064 nm and with a power of 1 W has been used to irradiate samarium tellurite glasses with the compositions of 10RO·10Sm2O3·80TeO2 (R=Mg, Ba) at room temperature for 30–60 s. It is found from polarized optical microscopy and from X-ray diffraction (XRD) analyses that crystalline dot patterns with sharp refractive index changes

Ryuji Sato; Yasuhiko Benino; Takumi Fujiwara; Takayuki Komatsu



INTERACTION OF LASER RADIATION WITH MATTER: Generation of a bleaching wave in an ST-50-1 glass ceramics induced by a Nd:YAG laser  

NASA Astrophysics Data System (ADS)

It is shown that upon exposing glass ceramics to laser radiation for which the initial polycrystalline phase is opaque, whereas the corresponding glass phase is transparent, the transparency oscillations can be produced due to the laser-induced phase transitions from the crystalline to amorphous state and vice versa, resulting in the propagation of a bleaching and darkening wave.

Veiko, V. P.; Novikov, B. Yu; Shakhno, E. A.; Yakovlev, E. B.



Diffusion in crystalline materials  

Microsoft Academic Search

Recently nuclear scattering of synchrotron radiation proved to be a powerful new method to study the elementary diffusion jump in crystalline solids. The scattered radiation decays faster when atoms move on the time scale of the excited-state lifetime of a Mössbauer isotope because of a loss of coherence. The acceleration of the decay rate differs for different crystal orientations relative

G. Vogl; B. Sepiol



Acceptor-donor-acceptor-based small molecules with varied crystallinity: processing additive-induced nanofibril in blend film for photovoltaic applications  

NASA Astrophysics Data System (ADS)

A series of acceptor-donor-acceptor-based small molecules (SMs) with varied crystallinity were successfully synthesized. The processing additive can induce the SMs to self-organize as nanofibrils with higher crystallinity and controlled scales of nanofibrils, which have significant influence on the photovoltaic performance.A series of acceptor-donor-acceptor-based small molecules (SMs) with varied crystallinity were successfully synthesized. The processing additive can induce the SMs to self-organize as nanofibrils with higher crystallinity and controlled scales of nanofibrils, which have significant influence on the photovoltaic performance. Electronic supplementary information (ESI) available: Synthetic process and characterizations of SMs; TGA, electrochemical properties, molecular orbital surfaces of SMs; AFM images of SM:PC71BM blend films; EQE curves; optical, electrochemical properties and photovoltaic parameters. See DOI: 10.1039/c3nr03048b

Li, Chao; Chen, Yujin; Zhao, Yue; Wang, Huifang; Zhang, Wei; Li, Yaowen; Yang, Xiaoming; Ma, Changqi; Chen, Liwei; Zhu, Xiulin; Tu, Yingfeng



Radiation-induced peripheral nerve neurofibromata in a patient receiving hypofractionated radiation therapy.  


Radiation-induced peripheral nerve tumor, in particular a benign entity such as a neurofibroma, is rare, with only a few cases being reported so far. We demonstrate a case of radiation-induced neurofibromata along the left cervical nerve roots in a man with a background of localized targeted hypofractionated radiation therapy as adjuvant treatment for left cervical nodal metastasis complicating nasopharyngeal carcinoma. The toxicity of high-dose radiation in a hypofractionated regime is also stressed. PMID:18653682

Lai, V; Wong, Y C; Poon, W L; Fu, Y P; Lam, T C; Yuen, S C



Physiological pathway of human cell damage induced by genotoxic crystalline silica nanoparticles.  


We disclosed a specific biological pathway for the observed cell damage when stimulated by the crystalline SiO(2) nanoparticles (NPs), i.e., both mitochondrion multiplication and DNA fragmentation occur upon the initial reactive oxygen species (ROS) generation, with the former causing further increases of the ROS level in the cell, and eventually leads to catastrophic effect on cell physiology. Such damage becomes nontrivial only in the absence of p53 gene, which regulates cells' anti-oxidation and detoxification. This genotoxic effect is absent in cells treated with amorphous SiO(2) NPs. PMID:22795858

Chu, Zhiqin; Huang, Yuanjie; Li, Lili; Tao, Qian; Li, Quan



Morphology-induced redistribution of surface plasmon modes in two-dimensional crystalline gold platelets  

NASA Astrophysics Data System (ADS)

The 2D optical field intensity distribution in sub-micron, ultrathin, and crystalline gold platelets is investigated by two-photon luminescence (TPL) microscopy. In particular, the evolution of the TPL maps as the particle morphology undergoes a transition from triangular to hexagonal reveals that the signatures of the high-order surface plasmon states sustained by the platelets follows the same C3v to C6v symmetry redistribution. Experimental observations are precisely accounted for by theoretical simulations based on the Green dyadic method.

Viarbitskaya, S.; Teulle, A.; Cuche, A.; Sharma, J.; Girard, C.; Dujardin, E.; Arbouet, A.



Current induced surface diffusion on a single-crystalline silver nanowire.  


Scanning tunnelling microscopy was used to study the morphological changes of the surface of a single-crystalline silver nanowire caused by a lateral electron current. At current densities of about 1.5 × 10(7) A cm(-2), surface atoms are extracted from step edges, resulting in the motion of surface steps, islands and holes with a thickness or depth of one monolayer. Upon current reversal the direction of the material transport can be altered. The findings are interpreted in terms of the wind force. PMID:22543691

Kaspers, M R; Bernhart, A M; Bobisch, C A; Möller, R



Ion beam induced luminescence: Relevance to radiation induced bystander effects  

NASA Astrophysics Data System (ADS)

The aim of this work is quantify the light emitted as a result of charged particle interaction in materials which may be of relevance to radiation induced "bystander effects" studies. We have developed a system which employs single photon counting to measure the light emitted from samples irradiated under vacuum by a charged particle beam. The system uses a fast photomultiplier tube with a peak cathode response at 420 nm. It has been tested in a proof-of-principle experiment using polystyrene targets. Light output, as a result of irradiation, was measured. The luminescence yield appears to have a non-linear behavior with the incident ion fluence: it rises exponentially to an asymptotic value. The target was irradiated with beam energies varying from 1 to 2 MeV and showed saturation at or before an incident fluence rate of 3 × 1013 H+/cm2 s. The average saturation value for the photon output was found to be 40 × 106 cps. Some measurements were performed using filters to study the emission at specific wavelengths. In the case of filtered light measurements, the photon output was found to saturate at 28 × 103, 10 × 106, and 35 × 106 cps for wavelengths of 280 ± 5 nm, 320 ± 5 nm and 340 ± 5 nm respectively. The light output reaches a maximum value because of damage induced in the polymer. Our measurements indicate a "damage cross section" of the order of 10-14 cm2. The average radiant intensity was found to increase at wavelengths of 280 and 320 nm when the proton energy was increased. This was not found to occur at 340 nm. In conclusion, the light emission at specific wavelengths was found to depend upon the incident proton fluence and the proton energy. The wavelengths of the emitted light measured in this study have significance for the understanding of radiation induced bystander effects.

Ahmad, S. B.; McNeill, F. E.; Byun, S. H.; Prestwich, W. V.; Seymour, C.; Mothersill, C. E.



Radiation Effects in Insulator Materials.  

National Technical Information Service (NTIS)

The thermal- and radiation-induced charges released to an external circuit have been examined for a set of polyethylene capacitors made from materials of differing crystallinities and molecular structures. Persistent internal fields were created by burn-i...

J. Wilkenfeld



Induced radioactivity in Bevatron concrete radiation shielding blocks.  

National Technical Information Service (NTIS)

The Bevatron accelerated protons up to 6.2 GeV and heavy ions up to 2.1 GeV/amu. It operated from 1954 to 1993. Radioactivity was induced in some concrete radiation shielding blocks by prompt radiation. Prompt radiation is primarily neutrons and protons t...

G. C. Moeller R. J. Donahue



Radiation Induced Surface Activity Phenomenon: 2. Report - Radiation Induced Boiling Enhancement  

SciTech Connect

To delineate the effect of Radiation Induced Surface Activity (RISA) on boiling phenomenon, surface wettability in high-temperature environment or Leidenfrost condition and critical heat flux (CHF) of oxide metals irradiated by gamma rays were investigated. When the temperature of the heating surface reaches the wetting limit temperature, water-solid contact vanishes because of a stable vapor film between the droplet and the metal surface, i.e., a Leidenfrost condition. The wetting limit temperature increased with integrated irradiation dose. The CHF of oxidized titanium was improved up to 100% after 800 kGy {sup 60}Co gamma ray irradiated. Radiation Induced Boiling Enhancement (RIBE) phenomenon was firstly confirmed through the experiments. (authors)

Tatsuya Koga; Yasuyuki Imai; Tomoji Takamasa [Tokyo University of Mercantile Marine, 2-1-6 Etchu-jima, Koto-Ku, Tokyo 135-8533 (Japan); Koji Okamoto [University of Tokyo (Japan); Kaichiro Mishima [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)



Clinical and dosimetric factors of radiation-induced esophageal injury: Radiation-induced esophageal toxicity  

Microsoft Academic Search

Abstract Abstract Abstract Abstract AIM: To analyze the clinical and dosimetric predictive factors for radiation-induced esophageal injury in patients with non-small-cell lung cancer (NSCLC) during three- dimensional conformal radiotherapy (3D-CRT). METHODS: We retrospectively analyzed 208 consecutive patients (146 men and 62 women) with NSCLC treated with 3D-CRT. The median age of the patients was 64 years (range 35-87 years). The

Wen-Bo Qiao; Yan-Hui Zhao; Yan-Bin Zhao; Rui-Zhi Wang


Radiation-induced degradation of DNA bases  

NASA Astrophysics Data System (ADS)

Radio-induced degradation of DNA involves radical processes. A series of lesions among the major bases degradation products has been measured in isolated DNA exposed to gamma radiation in aerated aqueous solution. Degradation can be accounted for by the formation of hydroxyl radicals upon radiolysis of water (indirect effect). The four bases are degraded in high yield. Direct effect has been mimicked by photo-induced electron abstraction from the bases producing their radical cation. Quantification of the modified bases showed that guanine is the preferential target. This can be explained by its lower oxidation potential and charge transfer phenomena. La décomposition radio-induite de l'ADN fait intervenir des processus radicalaires. Une série de lésions choisies parmi les produits majeurs de dégradation des bases a été mesurée dans de l'ADN isolé exposé au rayonnement en solution aqueuse aérée. Les modifications sont alors dues aux radicaux hydroxyles produits par la radiolyse de l'eau (effet indirect) et les quatre bases sont efficacement dégradées. L'arrachement d'électrons aux bases par photosensibilisation pour produire leur radical cation, a été utilisé comme modèle de l'effet direct. La quantification des bases modifiées montre que la guanine est préférentiellement dégradée. Cette observation peut s'expliquer par le plus faible potentiel d'oxydation de cette base ainsi que par les phénomènes de transfert de charge vers les guanines.

Douki, T.; Delatour, T.; Martini, R.; Cadet, J.



Supersymmetry breaking induced by radiative corrections  

NASA Astrophysics Data System (ADS)

We show that simultaneous gauge and supersymmetry breaking can be induced by radiative corrections, à la Coleman-Weinberg. When a certain correlation among the superpotential parameters is present, a local supersymmetry-breaking minimum is induced in the effective potential of a gauge non-singlet field, in a region where the tree-level potential is almost flat. Supersymmetry breaking is then transmitted to the MSSM through gauge and chiral messenger loops, thus avoiding the suppression of gaugino masses characteristic of direct gauge mediation models. The use of a single field ensures that no dangerous tachyonic scalar masses are generated at the one-loop level. We illustrate this mechanism with an explicit example based on an SU(5) model with a single adjoint. An interesting feature of the scenario is that the GUT scale is increased with respect to standard unification, thus allowing for a larger colour Higgs triplet mass, as preferred by the experimental lower bound on the proton lifetime.

Bajc, Borut; Lavignac, Stéphane; Mede, Timon



Single-crystalline Si on insulator in confined structures fabricated by two-step metal-induced crystallization of amorphous Si  

NASA Astrophysics Data System (ADS)

We present a technology and its mechanism to obtain single-crystalline Si pillars on SiO2 using a two-step Ni-induced crystallization process on amorphous Si pillars with confined sizes. The amorphous Si pillars with a Ni cap were first annealed at 400 °C for 15 h so that a single-crystalline NiSi2 template was formed on top of each pillar. In the second step, they were annealed at 550 °C for 2 h, during which single-crystalline Si pillars were formed by NiSi2-mediated solid-phase epitaxy. These single-crystalline Si pillars can be used for advanced vertical metal-oxide-semiconductor transistors and surround-gate structures, especially where low-temperature processing is required.

Liu, Yaocheng; Deal, Michael D.; Saraswat, Krishna C.; Plummer, James D.



Changing bioperformance of TiO2 amorphous nanotubes as an effect of inducing crystallinity.  


Controlled-diameter TiO(2) nanotubes were obtained by electrochemical anodizing of two different substrates (Ti and Ti6Al7Nb) in an aqueous electrolyte. As-formed TiO(2) nanotubes are amorphous and by subjecting to thermal treatments, the structure becomes crystalline. An optimal thermal treatment with a specific anatase/rutile ratio was chosen, determined from X-ray diffraction (XRD). The electrochemical behaviour of annealed and as-formed samples was followed with Tafel plots and Electrochemical impedance spectroscopy (EIS), while surface analysis involved scanning electron microscopy (SEM) and contact angle measurements (CA). Annealed samples have a more hydrophilic character than as-formed as well as a better stability in bioliquids. Such behaviour of annealed samples is connected with a better biocompatibility expressed in terms of cell morphology and gene expression of bone specific markers obtained from Reverse Transcription Polymerase Chain Reaction (RT-PCR). PMID:22341625

Mazare, A; Dilea, M; Ionita, D; Titorencu, I; Trusca, V; Vasile, E



Swelling characteristics of konjac glucomannan superabsobent synthesized by radiation-induced graft copolymerization  

NASA Astrophysics Data System (ADS)

Graft copolymerization of konjac glucomannan (KGM) and acrylic acid was induced by 60Co-? irradiation at room temperature. The effects of radiation dose and monomer-to-KGM ratio on grafting yield and equilibrium water absorbency were investigated. The KGM-based superabsorbent polymer (KSAP) could absorb water 625 times of its dry weight when the radiation dose was 5.0 kGy and monomer-to-KGM ratio was 5. The structure of KSAP was characterized by FTIR, XRD, and SEM. KSAP showed a lower crystallinity than KGM. The porous microstructure of KSAP was revealed by SEM. The diffusion mechanism of water in the hydrogel is consistent with the anomalous diffusion model. Cations, especially multivalent cations, greatly reduced water absorbency of KSAP. Rising temperature, acidic or basic solutions are not favorable for the swelling of KSAP.

Wu, Jia; Deng, Xiao; Lin, Xiangyang




Microsoft Academic Search

The method of recoilless nuclear resonance absorption of gamma radiation ; was employed to investigate the temperature dependence of the nuclear quadrupole ; interaction in the 8.4-kev level of Tm¹⁶⁹ in thulium ethyl sulfate. The ; experiment revealed a strong influence of electronic shielding resulting from the ; polarization induced in the closed electron shells by the crystalline electric ;

R. G. Barnes; E. Kankeleit; R. L. Moessbauer; J. M. Poindexter



Liquid crystalline bispropargyl thermosets  

SciTech Connect

A series of rigid-rod bispropargyl thermoset monomers have been synthesized. These monomers were examined by differential scanning calorimetry (DSC) and hot stage polarized optical microscopy. Enantiotropic or monotropic nematic liquid crystalline phases were observed for all but two monomers. Partial curing of these reactive liquid crystalline monomers resulted in the formation of stable liquid crystalline phases with broad nematic phase after partial curing. DSC investigations indicated that the onset temperature of thermally induced cross-linking was approximately 260 C and insensitive to the phase type. The rate of cure was insensitive to the phase in which the cure occurred due to the unusual reaction mechanism for the propargyl end group.

Langlois, D.A.; Benicewicz, B.C. [Los Alamos National Lab., NM (United States). Polymers and Coatings Group; Douglas, E.P. [Univ. of Florida, Gainesville, FL (United States). Dept. of Materials Science and Engineering



Coherent Cherenkov radiation from cosmic-ray-induced air showers.  


Very energetic cosmic rays entering the atmosphere of Earth will create a plasma cloud moving with almost the speed of light. The magnetic field of Earth induces an electric current in this cloud which is responsible for the emission of coherent electromagnetic radiation. We propose to search for a new effect: Because of the index of refraction of air, this radiation is collimated in a Cherenkov cone. To express the difference from usual Cherenkov radiation, i.e., the emission from a fast-moving electric charge, we call this magnetically induced Cherenkov radiation. We indicate its signature and possible experimental verification. PMID:21902308

de Vries, K D; van den Berg, A M; Scholten, O; Werner, K



Radiation-induced segregation in candidate fusion-reactor alloys  

SciTech Connect

The effect of radiation on surface segregation of minor and impurity elements has been studied in four candidate fusion reactor alloys. Radiation induced surface segregation of phosphorus was found in both 316 type stainless steel and in Nimonic PE-16. Segregation and depletion of the other alloying elements in 316 stainless steel agreed with that reported by other investigators. Segregation of nitrogen in ferritic HT-9 was enhanced by radiation but no phosphorus segregation was detected. No significant radiation enhanced or induced segregation was observed in a Ti-6Al-4V alloy. The results indicate that radiaton enhanced grain boundary segregation could contribute to the embrittlement of 316 SS and PE-16.

Brimhall, J.L.; Baer, D.R.; Jones, R.H.



Water sorption induced transformations in crystalline solid surfaces: characterization by atomic force microscopy.  


The effect of water sorption on the mobility of molecules on the surface of a crystalline anhydrous solid was investigated to understand the mechanism of its transformation to the corresponding hydrate. Theophylline was chosen as the model compound. The transition water activity for anhydrate to hydrate transformation, RH(T), and the deliquescence RH, RH(0), was determined to be 62% and 99%, respectively (25 degrees C). Atomic force microscopy (AFM) was used to study the surface changes of theophylline above and below the transition water activity. Contact-mode AFM showed that the jump-to-contact distance increased appreciably above RH(T), suggesting formation of solution on the surface. At RH(T) < RH < RH(0), using dynamic (AC/"tapping" mode) AFM, the movements of surface steps were visualized. These results from AFM indicated that, below RH(0), the formation of a thin solution film significantly increased surface mobility. Furthermore, when the anhydrate crystal surface was seeded with the hydrate, the propagation of a new hydrate phase was observed by polarized light microscopy. In conclusion, atomic force microscopy provided direct evidence that the phase transformation of anhydrous theophylline to theophylline monohydrate in the solid-state is mediated by a surface solution as a result of water adsorption. PMID:20574999

Chen, Dabing; Haugstad, Greg; Li, Zheng Jane; Suryanarayanan, Raj



Formation of crystalline ?-Al2O3 induced by variable substrate biasing during reactive magnetron sputtering  

NASA Astrophysics Data System (ADS)

Reactive magnetron sputtering is a widely used technique to deposit various materials such as oxides and nitrides with a superior control of morphology and stoichiometry. The adjustment of the film properties at a given substrate temperature is believed to be affected by the average energy per incorporated atom during film growth, which is controlled by the ion-to-neutral ratio in the film forming growth flux and the energy of the incident ions. This concept is tested for alumina growth in an rf-magnetron discharge by keeping , the average energy of the incident ions Eions, and the ion-to-neutral flux ratio constant, but varying only the energy distribution of the incident ions (ion energy distribution-IED). The influence of the IED on film growth is monitored by observing the transition of the films between x-ray amorphous Al2O3 to ?-Al2O3. The results reveal that the substrate temperature necessary for the transition to ?-crystalline films can be lowered by almost 100 °C, when the maximum energy of the incident ions is kept at 100 eV, while maintaining the energy per incorporated atom at 11 eV. This result is compared with TRIM calculations for the collision cascades of impacting ions.

Prenzel, M.; Kortmann, A.; von Keudell, A.; Nahif, F.; Schneider, J. M.; Shihab, M.; Brinkmann, R. P.



Mixing antisolvents induced modulation in the morphology of crystalline C60.  


We present systematic studies of the synthesis of fullerene (C60) crystals with diverse morphologies by liquid-liquid interfacial precipitation (LLIP) method based on different alcohols as antisolvents and aromatic benzene as a solvent. C60 crystals are grown at liquid-liquid interface of mixed isopropyl alcohol (IPA) and tertiary butyl alcohol (TBA) with C60 solution in benzene. The role of mixing IPA and TBA on the morphology of C60 crystal is investigated. One dimensional (1 D) C60 nanowhiskers and polygon-shaped 2D sheets have been grown with individual IPA/benzene and TBA/benzene system, respectively. However, C60 crystals of different morphology (1D, 2D or both), and the self-assembly of nano-sized C60 into micron-sized crystals could be obtained upon mixing IPA and TBA and it is the mixing ratio which determines the morphology. Raman scattering and power X-ray diffraction measurements have shown that these materials are crystalline with cubic and hexagonal structures. PMID:22962752

Shrestha, Lok Kumar; Hill, Jonathan P; Miyazawa, Kun'ichi; Ariga, Katsuhiko



Heavy-ion radiation induced bystander effect in mice  

NASA Astrophysics Data System (ADS)

Radiation-induced bystander effect is defined as the induction of damage in neighboring non-hit cells by signals released from directly-irradiated cells. Recently, Low dose of high LET radiation induced bystander effects in vivo have been reported more and more. It has been indicated that radiation induced bystander effect was localized not only in bystander tissues but also in distant organs. Genomic, epigenetic, metabolomics and proteomics play significant roles in regulating heavy-ion radiation stress responses in mice. To identify the molecular mechanism that underlies bystander effects of heavy-ion radiation, the male mice head were exposed to 2000mGy dose of 12C heavy-ion radiation and the distant organ liver was detected on 1h, 6h, 12h and 24h after radiation, respectively. MSAP was used to monitor the level of polymorphic DNA methylation changes. The results show that heavy-ion irradiate mouse head can induce liver DNA methylation changes significantly. The percent of DNA methylation changes are time-dependent and highest at 6h after radiation. We also prove that the hypo-methylation changes on 1h and 6h after irradiation. But the expression level of DNA methyltransferase DNMT3a is not changed. UPLC/Synapt HDMS G2 was employed to detect the proteomics of bystander liver 1h after irradiation. 64 proteins are found significantly different between treatment and control group. GO process show that six of 64 which were unique in irradiation group are associated with apoptosis and DNA damage response. The results suggest that mice head exposed to heavy-ion radiation can induce damage and methylation pattern changed in distant organ liver. Moreover, our findings are important to understand the molecular mechanism of radiation induced bystander effects in vivo.

Liang, Shujian; Sun, Yeqing; Zhang, Meng; Wang, Wei; Cui, Changna



Radiation-Induced Transient Absorption in Optical Fibers.  

National Technical Information Service (NTIS)

Transient absorption in optical fibers has been studied with emphasis on fast absorption components. Radiation damage was induced with a Febetron 706 electron accelerator, modified to deliver an electron pulse width of 1.1 ns. Dye lasers were synchronized...

L. D. Looner G. Turquet de Beauregard P. B. Lyons R. E. Kelly



UV laser radiation-induced modifications and microstructuring of glass  

Microsoft Academic Search

Modifications and microstructures are generated on the surface and in the volume of silicate glasses using pulsed UV laser radiation of small pulse length. During the interaction of pulsed excimer laser radiation and frequency- trippled Nd:YAG laser radiation with intensities below the removal-threshold of the cerium- and silver-doped multi- component silicate glass absorption centers in the UV are induced. Subsequent

Marc Talkenberg; Ernst W. Kreutz; Alexander Horn; Michael Jacquorie; Reinhart Poprawe



Induced Compton-scattering effects in radiation-transport approximations  

SciTech Connect

The method of characteristics is used to solve radiation transport problems with induced Compton scattering effects included. The methods used to date have only addressed problems in which either induced Compton scattering is ignored, or problems in which linear scattering is ignored. Also, problems which include both induced Compton scattering and spatial effects have not been considered previously. The introduction of induced scattering into the radiation transport equation results in a quadratic nonlinearity. Methods are developed to solve problems in which both linear and nonlinear Compton scattering are important. Solutions to scattering problems are found for a variety of initial photon energy distributions.

Gibson, D.R. Jr.



Repair Machinery for Radiation-Induced DNA Damage.  

National Technical Information Service (NTIS)

Understanding the DNA repair mechanisms for ionizing radiation (IR)- induced DNA damage and having prior knowledge of a patient's lR-specific repair capacity will help to determine how patients will respond to radiation therapy and to design more effectiv...

L. H. Thompson



Dose rate radiation induced linear CCD functional failure  

Microsoft Academic Search

The experiments of different dose rate radiation induced Charge Coupled Devices (CCD) functional failure are presented. The CCDs are divided into three groups with no shielding, shielding the output amplifiers, and shielding the photo sensing and the shift register areas with Pb during 60Co ? tests. The radiation tolerance depend on the dose rates whether the linear CCDs are shielded

Zujun Wang; Bengqi Tang; Zhigang Xiao; Minbo Liu; Yong Zhang; Shaoyan Huang



Radiation Induced Carcinogenesis; Epidemiology and Mechanisms: A Review  

Microsoft Academic Search

Exposure to ionizing radiation has been proven to cause cancer and initiate mutagenesis in human and animal cells. This paper reviews some of the epide- miological data collected over the past 60 years and literature describing the current search for a genetic link to radiation induced carcinogenesis. Increased incidences of Leukemia, Breast Cancer, Lung Cancer, Skin Cancer and Bone Can-

Stuart Anderson


Thermal Modulation of Radiation-Induced DNA Damage Responses  

Microsoft Academic Search

\\u000a The goal of this review is to delineate the interaction between the DNA damage response and the proteotoxicity induced by\\u000a hyperthermia which leads to increased sensitivity to ionizing radiation. The radiosensitization must come from an interaction\\u000a between the proteotoxicity induced by hyperthermia and DNA damage responses occurring after ionizing radiation. Recently,\\u000a the cellular response to DNA DSB has been described

Joseph L. Roti Roti; Robert P. VanderWaal; Andrei Laszlo


Stability of crystalline solids—II: Application to temperature-induced martensitic phase transformations in a bi-atomic crystal  

NASA Astrophysics Data System (ADS)

This paper applies the stability theory of crystalline solids presented in the companion paper (Part I) to the study of martensitic transformations found in shape memory alloys (SMA's). The focus here is on temperature-induced martensitic transformations of bi-atomic crystals under stress-free loading conditions. A set of temperature-dependent atomic potentials and a multilattice description are employed to derive the energy density of a prototypical SMA (B2 cubic austenite crystal). The bifurcation and stability behavior are then investigated with respect to two stability criteria (Cauchy Born (CB) and phonon). Using a 4-lattice description five different equilibrium crystal structures are predicted: B2 cubic, L1 tetragonal, B19 orthorhombic, Cmmm orthorhombic, and B19 monoclinic. For our chosen model only the B2 and B19 equilibrium paths have stable segments which satisfy both the CB- and phonon-stability criteria. These stable segments overlap in temperature indicating the possibility of a hysteretic temperature-induced proper martensitic transformation. The B2 and B19 crystal structures are common in SMA's and therefore the simulated jump in the deformation gradient at a temperature for which both crystals are stable is compared to experimental values for NiTi, AuCd, and CuAlNi. Good agreement is found for the two SMA's which have cubic to orthorhombic transformations (AuCd and CuAlNi).

Elliott, Ryan S.; Shaw, John A.; Triantafyllidis, Nicolas



Radiation-induced apoptosis in the eye structures: a review  

NASA Astrophysics Data System (ADS)

Apoptosis plays a crucial role in tissue homeostasis and in the removal of damaged cells from tissues. Both increased and insufficient cell death can lead to human diseases. Apoptotic process is under the control of physiological metabolism as well as a panel of genes. After exposure to radiation, membrane damages induce the membrane pathway signal transduction for cell apoptosis. The importance of the radiation-induced apoptosis in the different ocular tissues and its relationship to the radiation parameters are reviewed in this article. This topic of ocular research has not been addressed in detail in the literature.

Belkacémi, Yazid; Huchet, Aymeri; Baudouin, Christophe; Lartigau, Éric



Hyperbaric oxygen: Primary treatment of radiation-induced hemorrhagic cystitis  

SciTech Connect

Of 8 patients with symptoms of advanced cystitis due to pelvic radiation treated with hyperbaric oxygen 7 are persistently improved during followup. All 6 patients treated for gross hematuria requiring hospitalization have been free of symptoms for an average of 24 months (range 6 to 43 months). One patient treated for stress incontinence currently is dry despite little change in bladder capacity, implying salutary effect from hyperbaric oxygen on the sphincter mechanism. One patient with radiation-induced prostatitis failed to respond. This experience suggests that hyperbaric oxygen should be considered the primary treatment for patients with symptomatic radiation-induced hemorrhagic cystitis.

Weiss, J.P.; Neville, E.C.



Thermal cycling induced load on copper-ribbons in crystalline photovoltaic modules  

NASA Astrophysics Data System (ADS)

Solar module lifetime is limited by the fatigue behavior of its cell interconnectors: the copper-ribbons. Every change in temperature induces thermo-mechanical stresses in the module components due to their thermo-mechanical mismatch. The purpose of this work is to quantify this load on the copper-ribbons between the individual cells of a cell string during a thermal cycling test by measuring cell displacement using digital image correlation and to compare the results to finite element analysis (FEM). Furthermore with help of FEM the influences of different materials were investigated, allowing material and layout optimizations with respect to copper-ribbon loading.

Meier, R.; Kraemer, F.; Wiese, S.; Wolter, K.-J.; Bagdahn, J.



Electromechanical actuation and current-induced metastable states in suspended single-crystalline VO2 nanoplatelets  

SciTech Connect

Current-induced electromechanical actuation enabled by the metal-insulator transition in VO{sub 2} nanoplatelets is demonstrated. The Joule heating by a sufficient current flowing through suspended nanoplatelets results in formation of heterophase domain patterns and is accompanied by nanoplatelet deformation. The actuation action can be achieved in a wide temperature range below the bulk phase transition temperature (68 C). The observed current-sustained heterophase domain structures should be interpreted as distinct metastable states in free-standing and end-clamped VO{sub 2} samples. We analyze the main prerequisites for the realization of a current-controlled actuator based on the proposed concept.

Tselev, Alexander [ORNL; Budai, John D [ORNL; Strelcov, Evgheni [Southern Illinois University; Tischler, Jonathan Zachary [ORNL; Kolmakov, Andrei [Southern Illinois University; Kalinin, Sergei V [ORNL



Strain-induced effects on the dielectric constant for thin, crystalline rare earth oxides on silicon  

NASA Astrophysics Data System (ADS)

Thin epitaxial rare earth oxide layers on Si exhibit K values that are much larger than the known bulk values. We investigate the thickness dependence of that enhancement effect for epitaxial Gd2O3 on Si(111). Controlling the oxide composition in ternary (Gd1-xNdx)2O3 thin films enables us to tune the lattice mismatch to silicon and thus the K values of the dielectric layer from 13 (close to the bulk value) up to 20. We show that simple tetragonal distortion of the cubic lattice is not sufficient to explain the enhancement in K. Therefore, we propose more severe strain induced structural phase deformations.

Schwendt, D.; Osten, H. J.; Shekhter, P.; Eizenberg, M.



Light induced enhancement of minority carrier lifetime of chemically passivated crystalline silicon  

NASA Astrophysics Data System (ADS)

In this work we present the light effect on chemically passivated silicon surface.The passivation behavior is sensitive to silicon surface state and illumination.Minority carrier lifetime measurements vary from 2 ?s to 40 ?s for un-passivated and chemically passivated silicon samples, respectively.Light enhances the passivation effect by the formation of silicon-ethoxylate group SiOC2H5.We propose a mechanism to the passivation effect based on carrier-induced dissociation of I2.

Aouida, S.; Bachtouli, N.; Bessais, B.



Probing the photothermally induced phase transitions in single-crystalline vanadium dioxide nanobeams  

NASA Astrophysics Data System (ADS)

Using Raman spectroscopy, we demonstrated photothermally induced crystallographic phase transitions of vanadium dioxide (VO2) nanobeams clamped to and free-standing on a substrate. Compared to the temperature-dependent Raman measurements, the laser-power-dependent Raman characteristics provide substantial evidence for the photothermal origin of the phase transitions of the VO2 nanobeams. The laser power necessary to cause phase transitions in the free-standing nanobeam was approximately eight times smaller than the laser power used in the substrate-clamped nanobeam. Our study will enhance the understanding of the complex phase transitions of strongly correlated oxides and thereby provide a foundation for engineering desirable properties in novel devices.

Chang, Sung-Jin; Hong, Woong-Ki; Kim, Hae Jin; Lee, Jin Bae; Yoon, Jongwon; Ko, Heung Cho; Huh, Yun Suk



Pressure-induced depolarization and resonance in Raman scattering of single-crystalline boron carbide  

SciTech Connect

We report polarized and resonant Raman scattering of single-crystal boron carbide (B{sub 4}C) at high pressures. Significant intensity enhancements of 270 and 1086 cm{sup -1} Raman bands of B{sub 4}C have been observed at quasihydrostatic pressures higher than approx20 GPa. The pressure-induced intensity change of the 1086 cm{sup -1} band is mainly due to the resonance between excitation energy and electronic transition, whereas the intensity change of 270 cm{sup -1} band is caused by the depolarization effect. Importantly, the first-order phase transition has not been found at high quasihydrostatic pressures and all the Raman intensity changes along with the corresponding high-pressure lattice distortion can be recovered during unloading.

Guo Junjie; Zhang Ling; Fujita, Takeshi; Chen Mingwei [WPI Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Goto, Takashi [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)



Radiation-induced apoptosis in microvascular endothelial cells.  


The response of the microvasculature to ionizing radiation is thought to be an important factor in the overall response of both normal tissues and tumours. It has recently been reported that basic fibroblast growth factor (bFGF), a potent mitogen for endothelial cells, protects large vessel endothelial cells from radiation-induced apoptosis in vitro. Microvessel cells are phenotypically distinct from large vessel cells. We studied the apoptotic response of confluent monolayers of capillary endothelial cells (ECs) to ionizing radiation and bFGF. Apoptosis was assessed by identifying changes in nuclear morphology, recording cell detachment rates and by detecting internucleosomal DNA fragmentation. Withdrawal of bFGF alone induces apoptosis in these monolayers. The magnitude of this apoptotic response depends upon the duration of bFGF withdrawal. Irradiation (2-10 Gy) induces apoptosis in a dose-dependent manner. Radiation-induced apoptosis occurs in a discrete wave 6-10 h after irradiation, and radiation-induced apoptosis is enhanced in cultures that are simultaneously deprived of bFGF. For example, 6 h after 10 Gy, 44.3% (s.e. 6.3%) of cells in the monolayer simultaneously deprived of bFGF exhibit apoptotic morphology compared with 19.8% (s.e. 3.8%) in the presence of bFGF. These studies show that either bFGF withdrawal or ionizing radiation can induce apoptosis in confluent monolayers of capillary endothelial cells and that radiation-induced apoptosis can be modified by the presence of bFGF. PMID:9043022

Langley, R E; Bump, E A; Quartuccio, S G; Medeiros, D; Braunhut, S J



Alpha-B-crystallin induces an immune-regulatory and antiviral microglial response in preactive multiple sclerosis lesions.  


Microglial nodules are frequently observed in the normal-appearing white matter of multiple sclerosis (MS) patients. Previously, we have shown that these clusters, which we call "preactive MS lesions," are closely associated with stressed oligodendrocytes and myelin sheaths that contain markedly elevated levels of the small stress protein alpha-B-crystallin (HspB5). Here, we show that microglia in these lesions express the recently identified receptors for HspB5, that is, CD14, Toll-like receptor family 1 and 2 (TLR1 and TLR2), and several molecular markers of the microglial response to HspB5. These markers were identified by genome-wide transcript profiling of 12 primary human microglial cultures at 2 time points after exposure to HspB5. These data indicate that HspB5 activates production by microglia of an array of chemokines, immune-regulatory mediators, and a striking number of antiviral genes that are generally inducible by type I interferons. Together, our data suggest that preactive MS lesions are at least in part driven by HspB5 derived from stressed oligodendrocytes and may reflect a local attempt to restore tissue homeostasis. PMID:24042199

Bsibsi, Malika; Holtman, Inge R; Gerritsen, Wouter H; Eggen, Bart J L; Boddeke, Erik; van der Valk, Paul; van Noort, Johannes M; Amor, Sandra



What mechanisms/processes underlie radiation-induced genomic instability?  


Radiation-induced genomic instability is a modification of the cell genome found in the progeny of irradiated somatic and germ cells but that is not confined on the initial radiation-induced damage and may occur de novo many generations after irradiation. Genomic instability in the germ line does not follow Mendelian segregation and may have unpredictable outcomes in every succeeding generation. This phenomenon, for which there is extensive experimental data and some evidence in human populations exposed to ionising radiation, is not taken into account in health risk assessments. It poses an unknown morbidity/mortality burden. Based on experimental data derived over the last 20 years (up to January 2012) six mechanistic explanations for the phenomenon have been proposed in the peer-reviewed literature. This article compares these hypotheses with the empirical data to test their fitness to explain the phenomenon. As a conclusion, the most convincing explanation of radiation-induced genomic instability attributes it to an irreversible regulatory change in the dynamic interaction network of the cellular gene products, as a response to non-specific molecular damage, thus entailing the rejection of the machine metaphor for the cell in favour of one appropriate to a complex dissipative dynamic system, such as a whirlpool. It is concluded that in order to evaluate the likely morbidity/mortality associated with radiation-induced genomic instability, it will be necessary to study the damage to processes by radiation rather than damage to molecules. PMID:22955377

Karotki, Andrei V; Baverstock, Keith



Radiation-induced cognitive impairment-from bench to bedside  

PubMed Central

Approximately 100 000 patients per year in the United States with primary and metastatic brain tumor survive long enough (>6 months) to develop radiation-induced brain injury. Before 1970, the human brain was thought to be radioresistant; the acute central nervous system (CNS) syndrome occurs after single doses of ?30 Gy, and white matter necrosis can occur at fractionated doses of ?60 Gy. Although white matter necrosis is uncommon with modern radiation therapy techniques, functional deficits, including progressive impairments in memory, attention, and executive function have become increasingly important, having profound effects on quality of life. Preclinical studies have provided valuable insights into the pathogenic mechanisms involved in radiation-induced cognitive impairment. Although reductions in hippocampal neurogenesis and hippocampal-dependent cognitive function have been observed in rodent models, it is important to recognize that other brain regions are affected; non–hippocampal-dependent reductions in cognitive function occur. Neuroinflammation is viewed as playing a major role in radiation-induced cognitive impairment. During the past 5 years, several preclinical studies have demonstrated that interventional therapies aimed at modulating neuroinflammation can prevent/ameliorate radiation-induced cognitive impairment independent of changes in neurogenesis. Translating these exciting preclinical findings to the clinic offers the promise of improving the quality of life in patients with brain tumors who receive radiation therapy.

Greene-Schloesser, Dana; Robbins, Mike E.



Pathogenesis of Radiation-Induced Osteosarcomas.  

National Technical Information Service (NTIS)

Results backed by experiments are presented here for the osteosarcoma induction in mice after incorporation of radium-224 or thorium-227. The dose-response relationship for osteosarcoma induction by short-lived alpha radiation is very much influenced by t...

A. Luz



Radiation-induced cerebellar chondrosarcoma. Case report  

SciTech Connect

The authors report a case of chondrosarcoma arising in the cerebellum 16 years after treatment of a cerebellar malignant astrocytoma by subtotal resection and irradiation. It is thought that the chondrosarcoma arising within the intracranial cavity was a probable consequence of previous ionizing radiation.

Bernstein, M.; Perrin, R.G.; Platts, M.E.; Simpson, W.J.



Initial studies on the crystallinity of the mineral fraction and ash content of isolated human and bovine osteons differing in their degree of calcification  

Microsoft Academic Search

Summary Several groups containing 10–15 isolated osteons differing in their degree of maturity were analysed. Samples were isolated from undecalcified human and bovine bone sections. The crystallinity coefficient, defined as the ratio of the number of radiation-induced paramagnetic defects in the crystalline lattice of hydroxyapatite to the total ash content, was calculated. The results were compared with measurements performed on

A. Ascenzi; E. Bonucci; K. Ostrowski; A. Sliwowski; A. Dziedzic-Goc?awska; W. Stachowicz; J. Michalik



Radiation effects and annealing kinetics in crystalline silicates, phosphates and complex Nb-Ta-Ti oxides. FInal Report.  

National Technical Information Service (NTIS)

Interaction of heavy particles (alpha-recoil nuclei, fission fragments, implanted ions) with ceramics is complex because they have a wide range of structure types, complex compositions and chemical bonding is variable. Radiation damage can produce diverse...

R. C. Ewing



Pulsed radiation-induced attenuation in certain optical fibers  

Microsoft Academic Search

Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the pulsed radiation-induced attenuation was measured in two optical fibers considered to be 'nonrad-hard': the 50-micron-core, graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28 krad(Si), respectively. In

Jonathan D. Weiss



Pulsed radiation-induced attenuation in certain optical fibers  

Microsoft Academic Search

Using the X-ray pulse from the HERMES II simulation machine at Sandia National Laboratories, the author measured the pulsed radiation-induced attenuation in two optical fibers considered to be `non-rad-hard': the 50 ?m core graded-index fiber from Corning and the plastic (PMMA) fiber from the Mitsubishi Rayon Company. These fibers were exposed to radiation up to doses of 19.5 and 28

J. D. Weiss



Use of probiotics for prevention of radiation-induced diarrhea  

Microsoft Academic Search

AIM: To investigate the efficacy of a high-potency probiotic preparation on prevention of radiation-induced diarrhea in cancer patients. METHODS: This was a double-blind, placebo-controlled trial. Four hundred and ninety patients who underwent adjuvant postoperative radiation therapy after surgery for sigmoid, rectal, or cervical cancer were assigned to either the high-potency probiotic preparation VSL#3 (one sachet t.i.d. ,) or placebo starting

P Deli; G Sansotta; V Donato; P Frosina; G Messina; C De Renzis; G Famularo



Metal oxides immobilized fabrics by radiation induced graft polymerization  

NASA Astrophysics Data System (ADS)

Radiation induced graft polymerization is effective for adding a new functionality to various forms of existing polymers. Ion-exchange nonwoven fabrics by gamma radiation induced graft polymerization have been used as filters in air and liquid. However, these materials have no capability for removing non-ionic species, such as volatile organic compound and ozone. Manganese oxides immobilized fabrics were developed for removing ozone. In addition, these materials were capable of removing formaldehyde and arsenic. Fine particles of manganese oxides were observed on the fibers. New materials produced by radiation induced graft polymerization and metal immobilization were applicable for purification of contaminants in environment. Manufacturing process is applicable for immobilization of the other metal oxides.

Fujiwara, K.; Masubuchi, T.; Miyata, K.; Shiozawa, M.; Takato, T.; Harakawa, H.



Tristetraprolin Mediates Radiation-Induced TNF-? Production in Lung Macrophages  

PubMed Central

The efficacy of radiation therapy for lung cancer is limited by radiation-induced lung toxicity (RILT). Although tumor necrosis factor-alpha (TNF-?) signaling plays a critical role in RILT, the molecular regulators of radiation-induced TNF-? production remain unknown. We investigated the role of a major TNF-? regulator, Tristetraprolin (TTP), in radiation-induced TNF-? production by macrophages. For in vitro studies we irradiated (4 Gy) either a mouse lung macrophage cell line, MH-S or macrophages isolated from TTP knockout mice, and studied the effects of radiation on TTP and TNF-? levels. To study the in vivo relevance, mouse lungs were irradiated with a single dose (15 Gy) and assessed at varying times for TTP alterations. Irradiation of MH-S cells caused TTP to undergo an inhibitory phosphorylation at Ser-178 and proteasome-mediated degradation, which resulted in increased TNF-? mRNA stabilization and secretion. Similarly, MH-S cells treated with TTP siRNA or macrophages isolated from ttp (?/?) mice had higher basal levels of TNF-?, which was increased minimally after irradiation. Conversely, cells overexpressing TTP mutants defective in undergoing phosphorylation released significantly lower levels of TNF-?. Inhibition of p38, a known kinase for TTP, by either siRNA or a small molecule inhibitor abrogated radiation-induced TNF-? release by MH-S cells. Lung irradiation induced TTPSer178 phosphorylation and protein degradation and a simultaneous increase in TNF-? production in C57BL/6 mice starting 24 h post-radiation. In conclusion, irradiation of lung macrophages causes TTP inactivation via p38-mediated phosphorylation and proteasome-mediated degradation, leading to TNF-? production. These findings suggest that agents capable of blocking TTP phosphorylation or stabilizing TTP after irradiation could decrease RILT.

Ray, Dipankar; Shukla, Shirish; Allam, Uday Sankar; Helman, Abigail; Ramanand, Susmita Gurjar; Tran, Linda; Bassetti, Michael; Krishnamurthy, Pranathi Meda; Rumschlag, Matthew; Paulsen, Michelle; Sun, Lei; Shanley, Thomas P.; Ljungman, Mats; Nyati, Mukesh K.; Zhang, Ming; Lawrence, Theodore S.



Radiation induced growth of micro crystallites  

SciTech Connect

Generation of colloidal particles during the radiolysis of aqueous solutions was already observed in the early days of radiation chemistry. Systematic studies using radiation chemistry techniques as synthetic tools in the preparation of colloidal particles, primarily metallic particles, were begun approximately a decade ago in conjunction since they were found to catalyze multi-electron redox processes. A large number of metallic colloidal particles were then synthesized, including silver, gold, platinum, iridium, nickel, cadmium, and others. More recently, attention has turned to semiconductor colloidal particles. The stimulus to these studies is the observation of quantum size effects in small semiconductor particles that exhibit hybrid properties between those of the molecular species and the solid state bulk material. In the following we discuss our own observations on the evolution of semiconductor particles whose growth has been initiated by pulse radiolysis. 13 refs., 2 figs.

Meisel, D.



Radiation-induced transformations of cellulose ethers  

SciTech Connect

The purpose of this investigation was to study the transformation which take place under the action of ..gamma..-radiation in a number of cellulose ethers containing both saturated (carboxymethyl, hydroxyethyl) and unsaturated (allyl, methacryloyl) groups. Irradiation was carried out on a /sup 60/Co unit in air at 77 and 300 K; the dose rate was 37 and 50 kGy/h respectively. The EPR spectra of ..gamma..-irradiated hydroxyethyl- and allylhydroxyethylcelluloses are identical. Under the action of ..gamma..-radiation extensive changes took place in cellulose ethers which are exhibited in degradation or the formation of three-dimensional structures and are accompanied by a change in the functional composition. The efficiency in the formation of radicals and their localization are determined by the nature and number of substituents in the cellulose ethers.

Nud'ga, L.A.; Petropavlovskii, G.S.; Plisko, E.A.; Isakova, O.V.; Ershov, B.G.



Radiation-induced products of peptides and their enzymatic digestibility  

SciTech Connect

Chemical characterization of radiation-induced products of peptides and proteins is essential for understanding the effect of ionizing radiation on peptides and proteins. Furthermore, peptides containing radiation-altered amino acid residues might not be completely digestible by proteolytic enzymes. In this work, small homopeptides of Ala, Phe and Met were chosen as model peptides. Lysozyme was used to investigate the effect of ionizing radiation on a small protein. All peptides and lysozyme were irradiated in diluted, oxygen free, N/sub 2/O-saturated aqueous solutions, using a /sup 60/Co-..gamma..-source. HPLC, capillary GC and GC-MS were applied to isolate and characterize the radiation-induced products. The enzymatic digestibility of the products was investigated using aminopeptidase M, leucine aminopeptidase, carboxypeptidase A and carboxypeptidase Y. It was found that irradiation of peptides examined in this work leads to racemization and alteration of amino acid residues and crosslinks between the peptide chains. In addition, it was established that exopeptidases act differently on radiation-induced dimers of peptides composed of aliphatic, aromatic and sulfur-containing amino acids.

Gajewski, E.



Dielectric properties of laser-induced conditions in a hybrid composite made by doping a side-chain liquid crystalline polymer  

Microsoft Academic Search

A side-chain liquid crystalline polymer (SLCP) was investigated by measuring the laser-induced effects on molecular reorientation. A 20mW He–Cd (?=441.6nm) laser was used as a pumping source during the measurements, which were performed by an impedance analyzer to see the effect of laser illumination on the polymer-doped and non-polymered samples. Dielectric anisotropy dependency is quantitatively estimated via capacitive measurements. Our

S. E. San; M. Okutan; O. Koysal; H. Ono




Microsoft Academic Search

During the past decade evidence has accumulated that an appreciable ; portion of radiation-induced mutations are due to chemical effects of radiation ; on sensitive metabolites. The shape of induced mutation frequency curves ; suggests that intracellular radiation-sensitive material is modified by radiation. ; This material is probably both limited in quantity and destroyed by radiat high ; doses of

F. L. Haas; C. O. Doudney



Squamous cell carcinoma antigen suppresses radiation-induced cell death  

PubMed Central

Previous study has demonstrated that squamous cell carcinoma antigen (SCCA) 1 attenuates apoptosis induced by TNF?, NK cell or anticancer drug. In this study, we have examined the effect of SCCA2, which is highly homologous to SCCA1, but has different target specificity, against radiation-induced apoptosis, together with that of SCCA1. We demonstrated that cell death induced by radiation treatment was remarkably suppressed not only in SCCA1 cDNA-transfected cells, but also in SCCA2 cDNA-transfected cells. In these transfectants, caspase 3 activity and the expression of activated caspase 9 after radiation treatment were suppressed. Furthermore, the expression level of phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) was suppressed compared to that of the control cells. The expression level of upstream stimulator of p38 MAPK, phosphorylated MKK3/MKK6, was also suppressed in the radiation-treated cells. Thus, both SCCA1 and SCCA2 may contribute to survival of the squamous cells from radiation-induced apoptosis by regulating p38 MAPK pathway. © 2001 Cancer Research Campaign

Murakami, A; Suminami, Y; Hirakawa, H; Nawata, S; Numa, F; Kato, H



Mechanisms of radiation-induced neoplastic cell transformation  

SciTech Connect

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

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



Contribution of radiation-induced, nitric oxide-mediated bystander effect to radiation-induced adaptive response.  

NASA Astrophysics Data System (ADS)

There has been a recent upsurge of interest in radiation-induced adaptive response and bystander effect which are specific modes in stress response to low-dose low-dose rate radiation Recently we found that the accumulation of inducible nitric oxide NO synthase iNOS in wt p53 cells was induced by chronic irradiation with gamma rays followed by acute irradiation with X-rays but not by each one resulting in an increase in nitrite concentrations of medium It is suggested that the accumulation of iNOS may be due to the depression of acute irradiation-induced p53 functions by pre-chronic irradiation In addition we found that the radiosensitivity of wt p53 cells against acute irradiation with X-rays was reduced after chronic irradiation with gamma rays This reduction of radiosensitivity of wt p53 cells was nearly completely suppressed by the addition of NO scavenger carboxy-PTIO to the medium This reduction of radiosensitivity of wt p53 cells is just radiation-induced adaptive response suggesting that NO-mediated bystander effect may considerably contribute to adaptive response induced by radiation

Matsumoto, H.; Ohnishi, T.


Dynamics of plasma formation, relaxation, and topography modification induced by femtosecond laser pulses in crystalline and amorphous dielectrics  

SciTech Connect

We have studied plasma formation and relaxation dynamics along with the corresponding topography modifications in fused silica and sapphire induced by single femtosecond laser pulses (800 nm and 120 fs). These materials, representative of high bandgap amorphous and crystalline dielectrics, respectively, require nonlinear mechanisms to absorb the laser light. The study employed a femtosecond time-resolved microscopy technique that allows obtaining reflectivity and transmission images of the material surface at well-defined temporal delays after the arrival of the pump pulse which excites the dielectric material. The transient evolution of the free-electron plasma formed can be followed by combining the time-resolved optical data with a Drude model to estimate transient electron densities and skin depths. The temporal evolution of the optical properties is very similar in both materials within the first few hundred picoseconds, including the formation of a high reflectivity ring at about 7 ps. In contrast, at longer delays (100 ps-20 ns) the behavior of both materials differs significantly, revealing a longer lasting ablation process in sapphire. Moreover, transient images of sapphire show a concentric ring pattern surrounding the ablation crater, which is not observed in fused silica. We attribute this phenomenon to optical diffraction at a transient elevation of the ejected molten material at the crater border. On the other hand, the final topography of the ablation crater is radically different for each material. While in fused silica a relatively smooth crater with two distinct regimes is observed, sapphire shows much steeper crater walls, surrounded by a weak depression along with cracks in the material surface. These differences are explained in terms of the most relevant thermal and mechanical properties of the material. Despite these differences the maximum crater depth is comparable in both material at the highest fluences used (16 J/cm{sup 2}). The evolution of the crater depth as a function of fluence can be described taking into account the individual bandgap of each material.

Puerto, D.; Siegel, J.; Gawelda, W.; Galvan-Sosa, M.; Solis, J. [Laser Processing Group, Instituto de Optica-CSIC, Madrid (Spain); Ehrentraut, L. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Berlin (Germany); Bonse, J. [Bundesanstalt fuer Materialforschung und-pruefung (BAM), Berlin (Germany)



Crystalline solids.  


Many drugs exist in the crystalline solid state due to reasons of stability and ease of handling during the various stages of drug development. Crystalline solids can exist in the form of polymorphs, solvates or hydrates. Phase transitions such as polymorph interconversion, desolvation of solvate, formation of hydrate and conversion of crystalline to amorphous form may occur during various pharmaceutical processes, which may alter the dissolution rate and transport characteristics of the drug. Hence it is desirable to choose the most suitable and stable form of the drug in the initial stages of drug development. The current focus of research in the solid-state area is to understand the origins of polymorphism at the molecular level, and to predict and prepare the most stable polymorph of a drug. The recent advances in computational tools allow the prediction of possible polymorphs of the drug from its molecular structure. Sensitive analytical methods are being developed to understand the nature of polymorphism and to characterize the various crystalline forms of a drug in its dosage form. The aim of this review is to emphasize the recent advances made in the area of prediction and characterization of polymorphs and solvates, to address the current challenges faced by pharmaceutical scientists and to anticipate future developments. PMID:11325474

Vippagunta, S R; Brittain, H G; Grant, D J



Radiation-induced endometriosis in Macaca mulatta  

SciTech Connect

Female rhesus monkeys received whole-body doses of ionizing radiation in the form of single-energy protons, mixed-energy protons, X rays, and electrons. Endometriosis developed in 53% of the monkeys during a 17-year period after exposure. Incidence rates for endometriosis related to radiation type were: single-energy protons, 54%; mixed-energy protons, 73%; X rays, 71%; and electrons, 57%. The incidence of endometriosis in nonirradiated control monkeys was 26%. Monkeys exposed to single-energy protons, mixed-energy protons, and X rays developed endometriosis at a significantly higher rate than control monkeys (chi 2, P less than 0.05). Severity of endometriosis was staged as massive, moderate, and minimal. The incidence of these stages were 65, 16, and 19%, respectively. Observations of clinical disease included weight loss in 43% of the monkeys, anorexia in 35%, space-occupying masses detected by abdominal palpation in 55%, abnormal ovarian/uterine anatomy on rectal examination in 89%, and radiographic evidence of abdominal masses in 38%. Pathological lesions were endometrial cyst formation in 69% of the monkeys, adhesions of the colon in 66%, urinary bladder in 50%, ovaries in 86%, and ureters in 44%, focal nodules of endometrial tissue throughout the omentum in 59%, and metastasis in 9%. Clinical management of endometriosis consisted of debulking surgery and bilateral salpingo-oophorectomy combined in some cases with total abdominal hysterectomy. Postoperative survival rates at 1 and 5 years for monkeys recovering from surgery were 48 and 36%, respectively.

Fanton, J.W.; Golden, J.G. (USAF School of Aerospace Medicine, Brooks AFB, TX (USA))



Does the tumor microenvironment influence radiation-induced apoptosis?  

Microsoft Academic Search

Cytotoxic anti-cancer agents induce apoptosis in tumor and normal tissues. Therefore, it is important to investigate which\\u000a factors determine these apoptotic processes and hence their likely impact on therapeutic gain. Radiation-induced apoptosis\\u000a in tumors may be inhibited due to mutations of apoptotic elements or to tumor microenvironmental conditions arising from vascular\\u000a insufficiency. Tumors typically contain regions of hypoxia, low glucose

Alistair Hunter; Andre Hendrikse; Michael Renan; Raymond Abratt



Radiation-induced space charge in polymer film capacitors  

Microsoft Academic Search

A space-charge mapping technique was used to observe the formation of x-ray-induced space charge in poly(ethylene terephthalate) and polystyrene capacitor structures. Electronic transport processes, responsible for radiation-induced conductivity in these insulators, produced trapped space charge adjacent to the electrodes. These results were consistent with the conclusions of earlier photoconductivity measurements and revealed injection processes that limit the buildup of space

S. R. Kurtz; R. A. Anderson



Effect of solvents on radiation-induced ionic graft polymerization. [Gamma radiation  

SciTech Connect

The influence of various solvents on radiation-induced cationic (grafting of vinyl-n-butyl ether onto polyethylene) and anionic (grafting of 2-methyl-5-vinylpyridine onto polyethylene) graft polymerization was studied. This ionic grafting was performed in thoroughly dried systems at room temperature. It was established that electron-acceptor solvents promote cationic grafting but that electron-donor solvents promote the anionic. A clear correlation between the donor number of solvents and grafting value by the anionic mechanism was shown. There was no correlation between dielectric constants and grafting values. The reaction orders, according to monomer concentraton by 2-methyl-5-vinylpyridine grafting in various solvents, were equal to approximately 1.5 and 2 for the radical and anionic mechanisms, respectively. The effect of solvents on radiation-induced ionic graft polymerization is discussed. The results of this study indicate the correct choice of solvents for radiation-induced ionic grafting.

Kabanov, V.Ya.; Aliev, R.E.; Sidorova, L.P.



Interleukin-32 Positively Regulates Radiation-Induced Vascular Inflammation  

SciTech Connect

Purpose: To study the role of interleukin-32 (IL-32), a novel protein only detected in human tissues, in ionizing radiation (IR)-induced vascular inflammation. Methods and Materials: Irradiated (0-6 Gy) human umbilical vein endothelial cells treated with or without various agents-a cytosolic phospholipase A2 (cPLA2) inhibitor, a cyclooxygenase-2 (Cox-2) inhibitor, or lysophosphatidylcholines (LPCs)-were used to assess IL-32 expression by Northern blot analysis and quantitative reverse transcriptase-polymerase chain reaction. Expression of cell adhesion molecules and leukocyte adhesion to endothelial cells using human acute monocytic leukemia cell line (THP-1) cells was also analyzed. Results: Ionizing radiation dramatically increased IL-32 expression in vascular endothelial cells through multiple pathways. Ionizing radiation induced IL-32 expression through nuclear factor {kappa}B activation, through induction of cPLA2 and LPC, as well as induction of Cox-2 and subsequent conversion of arachidonic acid to prostacyclin. Conversely, blocking nuclear factor {kappa}B, cPLA2, and Cox-2 activity impaired IR-induced IL-32 expression. Importantly, IL-32 significantly enhanced IR-induced expression of vascular cell adhesion molecules and leukocyte adhesion on endothelial cells. Conclusion: This study identifies IL-32 as a positive regulator in IR-induced vascular inflammation, and neutralization of IL-32 may be beneficial in protecting from IR-induced inflammation.

Kobayashi, Hanako; Yazlovitskaya, Eugenia M. [Department of Radiation Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (United States); Lin, P. Charles [Department of Radiation Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (United States); Department of Cell and Development Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN (United States)], E-mail:



Countermeasures against space radiation induced oxidative stress in mice.  


Of particular concern for the health of astronauts during space travel is radiation from protons and high atomic number (Z), high energy particles (HZE particles). Space radiation is known to induce oxidative stress in astronauts after extended space flight. In the present study, the total antioxidant status was used as a biomarker to evaluate oxidative stress induced by proton and HZE particle radiation in the plasma of CBA mice and the protective effect of dietary supplement agents. The results indicate that exposure to proton and HZE particle radiation significantly decreased the plasma level of total antioxidants in the irradiated CBA mice. Dietary supplementation with L: -selenomethionine (SeM) or a combination of selected antioxidant agents (which included SeM) could partially or completely prevent the decrease in the total antioxidant status in the plasma of animals exposed to proton or HZE particle radiation. These findings suggest that exposure to space radiation may compromise the capacity of the host antioxidant defense system; this adverse biological effect can be prevented at least partially by dietary supplementation with agents expected to have effects on antioxidant activities. PMID:17387501

Kennedy, A R; Guan, J; Ware, J H



Radiation induced inter-device leakage degradation  

NASA Astrophysics Data System (ADS)

The evolution of inter-device leakage current with total ionizing dose in transistors in 180 nm generation technologies is studied with an N-type poly-gate field device (PFD) that uses the shallow trench isolation as an effective gate oxide. The overall radiation response of these structures is determined by the trapped charge in the oxide. The impacts of different bias conditions during irradiation on the inter-device leakage current are studied for the first time in this work, which demonstrates that the worst condition is the same as traditional NMOS transistors. Moreover, the two-dimensional technology computer-aided design simulation is used to understand the bias dependence.

Hu, Zhi-Yuan; Liu, Zhang-Li; Shao, Hua; Zhang, Zheng-Xuan; Ning, Bing-Xu; Chen, Ming; Bi, Da-Wei; Zou, Shi-Chang



Radiation-induced segregation in alloy X-750  

SciTech Connect

Microstructural and microchemical evolution of an Alloy X-750 heat under neutron irradiation was studied in order to understand the origin of irradiation-assisted stress corrosion cracking. Both clustering of point defects and radiation-induced segregation at interfaces were observed. Although no significant changes in the precipitate structure were observed, boundaries exhibited additional depletion of Cr and Fe and enrichment of Ni.

Kenik, E.A.



Cosmology for grand unified theories with radiatively induced symmetry breaking  

Microsoft Academic Search

The treatment of first-order phase transitions for standard grand unified theories is shown to break down for models with radiatively induced spontaneous symmetry breaking. It is argued that proper analysis of these transitions which would take place in the early history of the universe can lead to an explanation of the cosmological homogeneity, flatness, and monopole puzzles.

Andreas Albrecht; P. J. Steinhardt



Photo- and radiation-induced coordination defects in amorphous chalcogenides  

NASA Astrophysics Data System (ADS)

Photo- and radiation-induced destruction-polymerization transformations in amorphous As2S3 associated with coordination defects formation processes have been studied by differential IR Fourier spectroscopy method in the 400 - 100 cm-1 region. All topological variants of these processes, statistically possible in the investigated samples, have been taken into account for physical consideration of the real structural transformations.

Shpotyuk, Oleg I.




EPA Science Inventory

Determination of dose-response relationships for radiation-induced cancer in segments of the population with high susceptibility is critical for understanding the risks of low dose and low dose rates to humans. Clean-up levels for radionuclides will depend upon the fraction of t...


Kick Velocity Induced by Magnetic Dipole and Quadrupole Radiation  

Microsoft Academic Search

We examine the recoil velocity induced by the superposition of magnetic dipole and quadrupole radiation from a pulsar\\/magnetar born with rapid rotation. The resultant velocity depends on not the magnitude, but rather the ratio of the two moments and their geometrical configuration. The model does not necessarily lead to high spatial velocity for a magnetar with a strong magnetic field,

Yasufumi Kojima; Yugo E. Kato



Implementing initial state radiation for lepton induced processes in AMEGIC++  

NASA Astrophysics Data System (ADS)

We have implemented the method of Yennie, Frautschi, and Suura up to first order in alpha for the simulation of QED Initial State Radiation in lepton induced processes in AME. We consider s-channel processes via the exchange of scalar or vector resonances at electron and muon colliders.

Schälicke, Andreas; Krauss, Frank; Kuhn, Ralf; Soff, Gerhard



Radiation-induced mutagenicity and lethality in Salmonella typhimurium  

SciTech Connect

The mutagenic and lethal effects of ionizing radiation on histidine-deficient auxotrophs of Salmonella typhimurium were studied to improve the understanding of radiation damage to DNA. The auxotrophs were divided into two groups - one which is sensitive to base-pair substitutions and another sensitive to frameshifts. These groups were composed of parent-daughter pairs in which the chemical mutagenicity enhancing plasmid, pKM101, is absent in the parent strain and present in the daughter. Co-60 ..gamma..-radiation and 250 kV x-rays were used to irradiate the bacteria. Irradiation of the frameshift - sensitive strains which carry the pKm101 plasmid doubled the absolute number of induced revertants whereas irradiation of the base-pair substitution sensitive strain which also carries the pKm101 plasmid produced nearly no change in the number of induced revertants. A nearly negligible effect on the mutation rate was observed for all parent strains. (ACR)

Isildar, M.; Bakale, G.



Modulation of radiation-induced hemopoietic suppression by acute thrombocytopenia  

SciTech Connect

Modifications of radiation-induced hemopoietic suppression by acute thrombocytopenia were evaluated. Immediately before or after exposure to sublethal irradiation, mice were given a single injection of anti-mouse platelet serum (APS), normal heterologous serum, neuraminidase (N'ase), or saline, or no further treatment was provided. Hemopoiesis was evaluated by blood cell counts, hematocrits, and incorporation of (75Se)selenomethionine into platelets. APS and N'ase induced an acute thrombocytopenia from which there was partial recovery before the platelet count started to fall from the radiation. During the second post-treatment week, both thrombocytopoiesis and erythropoiesis were greater in mice that received APS or N'ase in addition to radiation than in control irradiated mice. Differences in leukopoiesis were not apparent. Therefore, both thrombocytopoiesis and erythropoiesis appeared to be responsive to a stimulus generated by acute thrombocytopenia in sublethally irradiated mice.

Ebbe, S.; Phalen, E.; Threatte, G.; Londe, H.



Expansion of nanosized pores in low-crystallinity nanoparticle-assembled plates via a thermally induced increase in solid-state density.  


We investigated thermally induced changes in a low-crystallinity hydroxyapatite (HAp)-nanoparticle-assembled plate containing nanosized pores. We first prepared an aqueous dispersion of low-crystallinity HAp nanoparticles (particle size, 48 nm) via a wet chemical process and then prepared the nanoparticle-assembled plate by drying the dispersion on an oil substrate to prevent crack formation. Before the plates were subjected to heat treatments, they contained 7.9-nm-sized pores because of the gap between the nanoparticles, and their porosity was 60%. After the heat treatments (600-1100 °C) were performed for 1 h, the solid-state density determined using helium pycnometry increased from 2.85 to 3.21 g/cm(3), and the pore size increased from 7.9 to 250 nm. These results indicate that the pore size expanded because of increases in crystallinity and density, despite the large decrease in the total volume because of thermally induced sintering of the nanoparticles. PMID:23777865

Okada, Masahiro; Fujiwara, Keiko; Uehira, Mayo; Matsumoto, Naoyuki; Takeda, Shoji



A Study of Radiation-Induced Cerebral Vascular Injury in Nasopharyngeal Carcinoma Patients with Radiation-Induced Temporal Lobe Necrosis  

PubMed Central

Purpose To investigate radiation-induced carotid and cerebral vascular injury and its relationship with radiation-induced temporal lobe necrosis in nasopharyngeal carcinoma (NPC) patients. Methods and Materials Fifty eight NPC patients with radiation-induced temporal lobe necrosis (TLN) were recruited in the study. Duplex ultrasonography was used to scan bilateral carotid arterials to evaluate the intima-media thickness (IMT) and occurrence of plaque formation. Flow velocities of bilateral middle cerebral arteries (MCAs), internal carotid arteries (ICAs) and basal artery (BA) were estimated through Transcranial Color Doppler (TCD). The results were compared with data from 33 patients who were free from radiation-induced temporal lobe necrosis after radiotherapy and 29 healthy individuals. Results Significant differences in IMT, occurrence of plaques of ICAs and flow velocities of both MCAs and ICAs were found between patients after radiotherapy and healthy individuals (p<0.05). IMT had positive correlation with post radiation interval (p?=?0.049). Compared with results from patients without radiation-induced TLN, the mean IMT was significantly thicker in patients with TLN (p<0.001). Plaques were more common in patients with TLN than patients without TLN (p?=?0.038). In addition, flow velocities of MCAs and ICAs in patients with TLN were much faster (p<0.001, p<0.001). Among patients with unilateral TLN, flow velocity of MCAs was significantly different between ipsilateral and contralateral sides to the lesion (p?=?0.001). Conclusion Thickening of IMT, occurrence of plaque formation and hemodynamic abnormality are more common in patients after radiotherapy, especially in those with TLN, compared with healthy individuals.

Xiang, Yanqun; Xing, Yigang; Tang, Yamei



Factors that modify risks of radiation-induced cancer  

SciTech Connect

The collective influence of biologic and physical factors that modify risks of radiation-induced cancer introduces uncertainties sufficient to deny precision of estimates of human cancer risk that can be calculated for low-dose radiation in exposed populations. The important biologic characteristics include the tissue sites and cell types, baseline cancer incidence, minimum latent period, time-to-tumor recognition, and the influence of individual host (age and sex) and competing etiologic influences. Physical factors include radiation dose, dose rate, and radiation quality. Statistical factors include time-response projection models, risk coefficients, and dose-response relationships. Other modifying factors include other carcinogens, and other biological sources (hormonal status, immune status, hereditary factors).

Fabrikant, J.I.



Radiation induced oxidative damage modification by cholesterol in liposomal membrane  

NASA Astrophysics Data System (ADS)

Ionizing radiation induced structural and chemical alterations in egg lecithin liposomal membrane have been studied by measurements of lipid peroxides, conjugated diene and fluorescence polarization. Predominantly unilamellar phospholipid vesicles prepared by sonication procedure were subjected to radiation doses of ?-rays from Co-60 in aerated, buffered aqueous suspensions. The oxidative damage in irradiated lipid molecules of liposomes has been determined spectrophotometrically by diene conjugate formation and thiobarbituric acid reactive (TBAR) method as a function of radiation dose. A correlation was found between the radiation dose applied (0.1-1 kGy) and the consequent lipid oxidation. The damage produced in irradiated liposomal membrane was measured by 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence decay and polarization. The observed decrease in DPH fluorescence and increase in polarization was found dependent on the radiation dose suggesting alterations in rigidity or organizational order in phospholipid bilayer after irradiation. Furthermore, irradiated liposome vesicles composed of cholesterol showed marked reduction in observed radiation mediated peroxide formation and significantly affected the DPH fluorescence parameters. The magnitude of these modifying effects were found dependent on the mole fraction of cholesterol. It is concluded that modulation of structural order in unilamellar vesicle membrane by variations in basic molecular components controlled the magnitude of lipid peroxidation and diene conjugate formation. These observations contribute to our understanding of mechanism of radical reaction mediated damage caused by ionizing radiation in phospholipid membrane.

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



Crystalline Beams  

NASA Astrophysics Data System (ADS)

Crystalline Beams are ordered stale of an ensemble of ions circulating in a Storage Ring with very small velocity fluctuations. They can be obtained from ordinary warm ion beams with the application of intense cooling techniques, namely electron and/or laser cooling. A phase transition occurs when sufficiently small velocity spreads are reached, freezing the particle-to-particle spacing in strings, zig-zags, and helices... The properties and feasibility of Crystalline Beams depend on the choice of the lattice of the Storage Ring. There are three issues closely related to the design of the Storage Ring, namely: the determination of Equilibrium Configurations, Confinement Conditions, and Stability Conditions. Of particular concern is the effect of the trajectory curvature and of the beam momentum spread. They both set the requirements on the amount of momentum cooling, on the focussing, and on the distribution of bending in the lattice of the Storage Ring. The practical demonstration of Crystalline Beams may create the basis for an advanced technology of particle accelerators. The limitations due to Coulomb intra-beam scattering and space-charge forces would be finally be brought under control, so that ordered beams of ions can be achieved for a variety of new applications.

Ruggiero, Alessandro G.



Radiation-induced cardiomyopathy as a function of radiation beam gating to the cardiac cycle  

NASA Astrophysics Data System (ADS)

Portions of the heart are often unavoidably included in the primary treatment volume during thoracic radiotherapy, and radiation-induced heart disease has been observed as a treatment-related complication. Such complications have been observed in humans following radiation therapy for Hodgkin's disease and treatment of the left breast for carcinoma. Recent attempts have been made to prevent re-stenosis following angioplasty procedures using external beam irradiation. These attempts were not successful, however, due to the large volume of heart included in the treatment field and subsequent cardiac morbidity. We suggest a mechanism for sparing the heart from radiation damage by synchronizing the radiation beam with the cardiac cycle and delivering radiation only when the heart is in a relatively hypoxic state. We present data from a rat model testing this hypothesis and show that radiation damage to the heart can be altered by synchronizing the radiation beam with the cardiac cycle. This technique may be useful in reducing radiation damage to the heart secondary to treatment for diseases such as Hodgkin's disease and breast cancer.

Gladstone, David J.; Flanagan, Michael F.; Southworth, Jean B.; Hadley, Vaughn; Thibualt, Melissa Wei; Hug, Eugen B.; Hoopes, P. Jack



Photocurrent Enhancement Induced By Interface Modifications Due To Low Dose Electron Irradiation Of Amorphous/Crystalline Silicon Heterojunctions  

SciTech Connect

A series of n-type amorphous silicon/p-type crystalline silicon solar cells has been exposed to different fluences of 1 MeV electrons. For intermediate fluences up to 1.10{sup 13} electrons/cm{sup 2}, an enhancement of the spectral response at shorter wavelengths and a increase of the short circuit current has been observed, while for higher fluences the usual device degradation due to the decrease of the charge carrier diffusion length in the crystalline silicon base after irradiation has been found.

Neitzert, Heinz-Christoph; Ferrara, Manuela [DIIIE, Universita di Salerno, Via Ponte Don Melillo 1, 84084 Fisciano (Saudi Arabia) (Italy); Fahrner, Wolfgang; Scherff, Maximilian [Chair of Electronic Devices, University Hagen, Haldener Str. 182, 58084 Hagen (Germany); Klaver, Arjen; Swaaij, Rene van [DIMES-ECTM, Delft University of Technology, P.O. Box 5053, 2600 GB Delft (Netherlands)



Radiation-induced mesotheliomas in rats  

SciTech Connect

Mesotheliomas have been reported in rats that inhaled plutonium, but these tumors have not been extensively studied. To investigate a possible role for inhaled radionuclides in the induction of mesotheliomas, four life-span studies conducted at the Inhalation Toxicology Research Institute are reviewed. A total of 3076 F344 rats were exposed by inhalation to aerosols of {sup 239}PuO{sub 2}, mixed uranium-plutonium oxide, or {sup 144}CeO{sub 2}. Results showed that a low incidence of pleural mesotheliomas was induced by either alpha- or beta-emitting radionuclides deposited and retained in the lung. Chronic alpha irradiation was more effective per unit dose in producing mesotheliomas than chronic beta irradiation of the lung by a factor of 15. 7 refs., 1 tab., 7 figs. (MHB)

Hahn, F.F.; Haley, P.J.; Hubbs, A.F.; Hoover, M.D.; Lundgren, D.L.



Radiation-induced skin carcinomas of the head and neck  

SciTech Connect

Radiation exposures to the scalp during childhood for tinea capitis were associated with a fourfold increase in skin cancer, primarily basal cell carcinomas, and a threefold increase in benign skin tumors. Malignant melanoma, however, was not significantly elevated. Overall, 80 neoplasms were identified from an extensive search of the pathology logs of all major hospitals in Israel and computer linkage with the national cancer registry. Radiation dose to the scalp was computed for over 10,000 persons irradiated for ringworm (mean 7 Gy), and incidence rates were contrasted with those observed in 16,000 matched comparison subjects. The relative risk of radiogenic skin cancer did not differ significantly between men or women or by time since exposure; however, risk was greatest following exposures in early childhood. After adjusting for sex, ethnic origin, and attained age, the estimated excess relative risk was 0.7 per Gy and the average excess risk over the current follow-up was 0.31/10(4) PY-Gy. The risk per Gy of radiation-induced skin cancer was intermediate between the high risk found among whites and no risk found among blacks in a similar study conducted in New York City. This finding suggests the role that subsequent exposure to uv radiation likely plays in the expression of a potential radiation-induced skin malignancy.

Ron, E.; Modan, B.; Preston, D.; Alfandary, E.; Stovall, M.; Boice, J.D. Jr. (National Cancer Institute, Bethesda, MD (USA))



Radiation induced corrosion of copper for spent nuclear fuel storage  

NASA Astrophysics Data System (ADS)

The long term safety of repositories for radioactive waste is one of the main concerns for countries utilizing nuclear power. The integrity of engineered and natural barriers in such repositories must be carefully evaluated in order to minimize the release of radionuclides to the biosphere. One of the most developed concepts of long term storage of spent nuclear fuel is the Swedish KBS-3 method. According to this method, the spent fuel will be sealed inside copper canisters surrounded by bentonite clay and placed 500 m down in stable bedrock. Despite the importance of the process of radiation induced corrosion of copper, relatively few studies have been reported. In this work the effect of the total gamma dose on radiation induced corrosion of copper in anoxic pure water has been studied experimentally. Copper samples submerged in water were exposed to a series of total doses using three different dose rates. Unirradiated samples were used as reference samples throughout. The copper surfaces were examined qualitatively using IRAS and XPS and quantitatively using cathodic reduction. The concentration of copper in solution after irradiation was measured using ICP-AES. The influence of aqueous radiation chemistry on the corrosion process was evaluated based on numerical simulations. The experiments show that the dissolution as well as the oxide layer thickness increase upon radiation. Interestingly, the evaluation using numerical simulations indicates that aqueous radiation chemistry is not the only process driving the corrosion of copper in these systems.

Björkbacka, Åsa; Hosseinpour, Saman; Johnson, Magnus; Leygraf, Christofer; Jonsson, Mats



Immobilization of Yeast Cells with Various Porous Carriers by Radiation-Induced Polymerization.  

National Technical Information Service (NTIS)

Yeast cells were immobilized by radiation-induced polymerization in twice. Various kinds of porous polymer carriers were prepared by radiation-induced polymerization of glass-forming monomers at a low temperature. Precultured yeast cells were incubated ae...

T. Fujimura I. Kaetsu



Chromosome aberrations induced by high-LET radiations.  


Measurements of chromosome aberrations in peripheral blood lymphocytes are currently the most sensitive and reliable indicator of radiation exposure that can be used for biological dosimetry. This technique has been implemented recently to study radiation exposures incurred by astronauts during space flight, where a significant proportion of the dose is delivered by high-LET particle exposure. Traditional methods for the assessing of cytogenetic damage in mitotic cells collected at one time point after exposure may not be suitable for measuring high-LET radiation effects due to the drastic cell cycle perturbations and interphase cell death induced by this type of exposure. In this manuscript we review the recent advances in methodology used to study high-LET induced cytogenetic effects and evaluate the use of chemically-induced Premature Chromosome Condensation (PCC) as an alternative to metaphase analysis. Published data on the cytogenetic effects of in vitro exposures of high-LET radiation is reviewed, along with biodosimetry results from astronauts after short or long space missions. PMID:15858388

Kawata, Tetsuya; Ito, Hisao; George, Kerry; Wu, Honglu; Cucinotta, Francis A



Radiation-induced optic neuropathy: A magnetic resonance imaging study  

SciTech Connect

Optic neuropathy induced by radiation is an infrequent cause of delayed visual loss that may at times be difficult to differentiate from compression of the visual pathways by recurrent neoplasm. The authors describe six patients with this disorder who experienced loss of vision 6 to 36 months after neurological surgery and radiation therapy. Of the six patients in the series, two had a pituitary adenoma and one each had a metastatic melanoma, multiple myeloma, craniopharyngioma, and lymphoepithelioma. Visual acuity in the affected eyes ranged from 20/25 to no light perception. Magnetic resonance (MR) imaging showed sellar and parasellar recurrence of both pituitary adenomas, but the intrinsic lesions of the optic nerves and optic chiasm induced by radiation were enhanced after gadolinium-diethylenetriaminepenta-acetic acid (DTPA) administration and were clearly distinguishable from the suprasellar compression of tumor. Repeated MR imaging showed spontaneous resolution of gadolinium-DTPA enhancement of the optic nerve in a patient who was initially suspected of harboring recurrence of a metastatic malignant melanoma as the cause of visual loss. The authors found the presumptive diagnosis of radiation-induced optic neuropathy facilitated by MR imaging with gadolinium-DTPA. This neuro-imaging procedure may help avert exploratory surgery in some patients with recurrent neoplasm in whom the etiology of visual loss is uncertain.

Guy, J.; Mancuso, A.; Beck, R.; Moster, M.L.; Sedwick, L.A.; Quisling, R.G.; Rhoton, A.L. Jr.; Protzko, E.E.; Schiffman, J. (Univ. of Florida, Gainesville (USA))



Radiation-induced cell death: importance of lysosomal destabilization.  


The mechanisms involved in radiation-induced cellular injury and death remain incompletely understood. In addition to the direct formation of highly reactive hydroxyl radicals (HO*) by radiolysis of water, oxidative stress events in the cytoplasm due to formation of H2O2 may also be important. Since the major pool of low-mass redox-active intracellular iron seems to reside within lysosomes, arising from the continuous intralysosomal autophagocytotic degradation of ferruginous materials, formation of H2O2 inside and outside these organelles may cause lysosomal labilization with release to the cytosol of lytic enzymes and low-mass iron. If of limited magnitude, such release may induce 'reparative autophagocytosis', causing additional accumulation of redox-active iron within the lysosomal compartment. We have used radio-resistant histiocytic lymphoma (J774) cells to assess the importance of intralysosomal iron and lysosomal rupture in radiation-induced cellular injury. We found that a 40 Gy radiation dose increased the 'loose' iron content of the (still viable) cells approx. 5-fold when assayed 24 h later. Cytochemical staining revealed that most redox-active iron was within the lysosomes. The increase of intralysosomal iron was associated with 'reparative autophagocytosis', and sensitized cells to lysosomal rupture and consequent apoptotic/necrotic death following a second, much lower dose of radiation (20 Gy) 24 h after the first one. A high-molecular-mass derivative of desferrioxamine, which specifically localizes intralysosomally following endocytic uptake, added to the culture medium before either the first or the second dose of radiation, stabilized lysosomes and largely prevented cell death. These observations may provide a biological rationale for fractionated radiation. PMID:15813701

Persson, H Lennart; Kurz, Tino; Eaton, John W; Brunk, Ulf T



The radiation-induced changes in rectal mucosa: Hyperfractionated vs. hypofractionated preoperative radiation for rectal cancer  

SciTech Connect

Purpose: The purpose of the study was the qualitative and quantitative evaluation of acute radiation-induced rectal changes in patients who underwent preoperative radiotherapy according to two different irradiation protocols. Patients and Methods: Sixty-eight patients with rectal adenocarcinoma underwent preoperative radiotherapy; 44 and 24 patients underwent hyperfractionated and hypofractionated protocol, respectively. Fifteen patients treated with surgery alone served as a control group. Five basic histopathologic features (meganucleosis, inflammatory infiltrations, eosinophils, mucus secretion, and erosions) and two additional features (mitotic figures and architectural glandular abnormalities) of radiation-induced changes were qualified and quantified. Results: Acute radiation-induced reactions were found in 66 patients. The most common were eosinophilic and plasma-cell inflammatory infiltrations (65 patients), erosions, and decreased mucus secretion (54 patients). Meganucleosis and mitotic figures were more common in patients who underwent hyperfractionated radiotherapy. The least common were the glandular architectural distortions, especially in patients treated with hypofractionated radiotherapy. Statistically significant differences in morphologic parameters studied between groups treated with different irradiation protocols were found. Conclusion: The system of assessment is a valuable tool in the evaluation of radiation-induced changes in the rectal mucosa. A greater intensity of regenerative changes was found in patients treated with hyperfractionated radiotherapy.

Starzewski, Jacek J. [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Pajak, Jacek T. [Department of Pathology, Medical University of Silesia, Katowice (Poland); Pawelczyk, Iwona [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Lange, Dariusz [Department of Tumor Pathology, Comprehensive Cancer Center Division, Gliwice (Poland); Golka, Dariusz [Department of Pathology, Medical University of Silesia, Katowice (Poland)]. E-mail:; Brzeziska, Monika [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland); Lorenc, Zbigniew [Department of General and Colorectal Surgery, Medical University of Silesia, Sosnowiec (Poland)



Radiation induced degradation of dyes--an overview.  


Synthetic dyes are a major part of our life. Products ranging from clothes to leather accessories to furniture all depend on extensive use of organic dyes. An unfortunate side effect of extensive use of these chemicals is that huge amounts of these potentially carcinogenic compounds enter our water supplies. Various advanced oxidation processes (AOPs) including the use of high-energy radiation have been developed to degrade these compounds. In this review, dye decoloration and degradation as a result of its exposure to high energy radiation such as gamma radiation and pulsed electron beam are discussed in detail. The role of various transient species such as H, OH and e(aq)(-) are taken into account as reported by various researchers. Literature citations in this area show that e(aq)(-) is very effective in decolorization but is less active in the further degradation of the products formed. The degradation of the dyes is initiated exclusively by OH attack on electron-rich sites of the dye molecules. Additionally, various parameters that affect the efficiency of radiation induced degradation of dyes, such as effect of radiation dose, oxygen, pH, hydrogen peroxide, added ions and dye classes are also reviewed and summarized. Lastly, pilot plant application of radiation for wastewater treatment is briefly discussed. PMID:19128875

Rauf, M A; Ashraf, S Salman



Oxidative Stress Mediates Radiation Lung Injury by Inducing Apoptosis  

SciTech Connect

Purpose: Apoptosis in irradiated normal lung tissue has been observed several weeks after radiation. However, the signaling pathway propagating cell death after radiation remains unknown. Methods and Materials: C57BL/6J mice were irradiated with 15 Gy to the whole thorax. Pro-apoptotic signaling was evaluated 6 weeks after radiation with or without administration of AEOL10150, a potent catalytic scavenger of reactive oxygen and nitrogen species. Results: Apoptosis was observed primarily in type I and type II pneumocytes and endothelium. Apoptosis correlated with increased PTEN expression, inhibition of downstream PI3K/AKT signaling, and increased p53 and Bax protein levels. Transforming growth factor-{beta}1, Nox4, and oxidative stress were also increased 6 weeks after radiation. Therapeutic administration of AEOL10150 suppressed pro-apoptotic signaling and dramatically reduced the number of apoptotic cells. Conclusion: Increased PTEN signaling after radiation results in apoptosis of lung parenchymal cells. We hypothesize that upregulation of PTEN is influenced by Nox4-derived oxidative stress. To our knowledge, this is the first study to highlight the role of PTEN in radiation-induced pulmonary toxicity.

Zhang Yu; Zhang Xiuwu; Rabbani, Zahid N. [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); Jackson, Isabel L. [Department of Pathology, Duke University Medical Center, Durham, NC (United States); Vujaskovic, Zeljko, E-mail: [Department of Radiation Oncology, Duke University Medical Center, Durham, NC (United States); Department of Pathology, Duke University Medical Center, Durham, NC (United States)



Effects of crystallinity on laser-induced voltage effect from Zn0.9Co0.1O thin film  

NASA Astrophysics Data System (ADS)

Co-doped ZnO epilayer films were grown by pulsed laser deposition (PLD) on vicinal cut silicon and sapphire substrates. Changes in deposition time were observed as a moderate effect on the quality of the films, and the influence of the thickness on thermoelectric signals from Zn0.9Co0.1O thin films were discussed. The effect of one of the main deposition parameters, the deposition time, on the crystallinity and electron mobility properties of the Zn0.9Co0.1O thin films grown on sapphire was investigated by means of X-ray diffraction (XRD) and laser-induced voltage (LIV) effect. It shown that the XRD rocking curve full-width half-maximun (FWHM) decreased as time increasing, and the LIV signals were observed along the tilting angle of the substrate orientation when the pulsed KrF excimer laser of 248 nm were irradiated on the films. When the films illuminated in pulse lasers, the highest signals occurred in the films with best crystalline quality, and the signals were higher in the films grown on sapphire than those on silicon substrates. It suggested that the electrical resistivity and electron mobility have close relations with not only the crystallinity but also with the interface of the thin films.

Zhou, X. F.; Lu, M. H.; Zhang, H.; Yan, H.; He, C. L.; Hao, R. Y.



Opportunities for nutritional amelioration of radiation-induced cellular damage.  


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

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



Probabilistic methodology for estimating radiation-induced cancer risk  

SciTech Connect

The RICRAC computer code was developed at Oak Ridge National Laboratory to provide a versatile and convenient methodology for radiation risk assessment. The code allows as input essentially any dose pattern commonly encountered in risk assessments for either acute or chronic exposures, and it includes consideration of the age structure of the exposed population. Results produced by the analysis include the probability of one or more radiation-induced cancer deaths in a specified population, expected numbers of deaths, and expected years of life lost as a result of premature fatalities. These calculatons include consideration of competing risks of death from all other causes. The program also generates a probability frequency distribution of the expected number of cancers in any specified cohort resulting from a given radiation dose. The methods may be applied to any specified population and dose scenario.

Dunning, D.E. Jr.; Leggett, R.W.; Williams, L.R.



Radiation induced bystander effects: Implications for low dose radiation risk assessment  

NASA Astrophysics Data System (ADS)

Current model used in radiation risk assessment is based on the dogma that the DNA of the nucleus is the main target for radiation-induced genotoxicity and, as fewer cells are directly damaged at low doses, the deleterious effects of radiation proportionally decline. Using a precision microbeam to target an exact fraction of cells in a population and irradiated their nuclei with exactly one alpha particle each, we found that the frequencies of induced mutations and chromosomal changes in populations where some known fractions of nuclei were hit are consistent with non- hit cells contributing significantly to the response. In fact, irradiation of 10% of a mammalian cell population with a single alpha particle per cell results in a mutant yield similar to that observed when all of the cells in the population are irradiated. This effect was significantly eliminated in cells pretreated with gap junction inhibitor or in cells carrying a dominant negative connexin 43 vector. The data imply that the relevant target for radiation mutagenesis is larger than an individual cell and suggest a need to reconsider the validity of the linear extrapolation in making risk estimate for low dose radiation exposure.

Zhou, H.; Suzuki, M.; Randers-Pehrson, G.; Waldren, C.; Hei, T.


Caffeine Markedly Enhanced Radiation-Induced Bystander Effects  

NASA Astrophysics Data System (ADS)

In this paper it is shown that incubation with 2 mM caffeine enhanced significantly the MN (micronucleus) formation in both the 1 cGy ?-particle irradiated and non-irradiated bystander regions. Moreover, caffeine treatment made the non-irradiated bystander cells more sensitive to damage signals. Treated by c-PTIO(2-(4-carboxy-phenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide), a nitric oxide (NO) scavenger, the MN frequencies were effectively inhibited, showing that nitric oxide might be very important in mediating the enhanced damage. These results indicated that caffeine enhanced the low dose ?-particle radiation-induced damage in irradiated and non-irradiated bystander regions, and therefore it is important to investigate the relationship between the radiosensitizer and radiation-induced bystander effects (RIBE).

Jiang, Erkang; Wu, Lijun



[Radiation-induced and therapy-related AML/MDS].  


Radiation induced acute myeloid leukemia (AML) was recognized a century ago, soon after mankind found radiation. Atomic bomb survivors developed de novo AML with relatively short latency with very high frequency. By contrast, excess occurrence of myelodysplastic syndrome (MDS) as well as solid tumors was found decades late. This difference may be due to etiology that many de novo AML patients harbor chimeric leukemogenic genes caused by chromosomal translocations, while MDS patients rarely carry chimeras. In addition, epigenetic change would play important roles. Therapy related leukemia is mainly caused by topoisomerase II inhibitors that cause de novo AML with an 11q23 translocation or by alkyrating agents that induce MDS/AML with an AML1 point mutation and monosomy 7. PMID:19860183

Inaba, Toshiya



Frequency and characteristics of docetaxel-induced radiation recall phenomenon  

SciTech Connect

Purpose: The aim of this study was to investigate the frequency and characteristics of a docetaxel-induced radiation recall phenomenon. Methods and Materials: Past histories of radiotherapy and radiation recall phenomenon (RRP) were analyzed in 461 patients who were administered docetaxel at our hospital between September 2002 and November 2005. Results: Of the 461 patients, 171 underwent radiotherapy before starting docetaxel. RRP was noted in 3 patients (1.8%). The 3 cases show that RRP tends to develop in patients treated with lower-energy photon beams of {<=}6 MV and in patients with marked acute phase reactions during radiotherapy. Conclusions: The incidence of RRP induced by docetaxel was 1.8%, making it a comparatively rare condition. However, docetaxel is increasingly being used for patients with head and neck tumors, and caution regarding development of RRP is warranted after use of docetaxel after high-dose radiotherapy with photon beams of {<=}6 MV.

Mizumoto, Masashi [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan)]. E-mail:; Harada, Hideyuki [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan); Asakura, Hirofumi [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan); Zenda, Sadamoto [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan); Fuji, Hiroshi [Division of Proton Therapy, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan); Murayama, Shigeyuki [Division of Proton Therapy, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan); Nishimura, Tetsuo [Division of Radiation Oncology, Shizuoka Cancer Center Hospital, Nagaizumi, Shizuoka (Japan)



Non-radiation induced signals in TL dosimetry.  


One source of background signals, which are non-radiation related, is the reader system and it includes dark current, external contaminants and electronic spikes. These factors can induce signals equivalent to several hundredths of mSv. Mostly, the effects are minimised by proper design of the TLD reader, but some effects are dependent on proper operation of the system. The other main group of background signals originates in the TL crystal and is due to tribothermoluminescence, dirt, chemical reactions and stimulation by visible or UV light. These factors can have a significant contribution, equivalent to over several mSv, depending on whether the crystal is bare or protected by PTFE. Working in clean environments, monitoring continuously the glow curves and performing glow curve deconvolution are suggested to minimise non-radiation induced spurious signals. PMID:12382710

German, U; Weinstein, M



Single-walled carbon nanotube-induced crystallinity on the electropolymeric film of tetraaminophthalocyaninatonickel(II) complex: Impact on the rate of heterogeneous electron transfer  

NASA Astrophysics Data System (ADS)

We present a fundamental investigation on the impact of single-walled carbon nanotube (SWCNT) on the film structure and redox behaviour of tetraaminophthalocyaninatonickel(II) complex (NiTAPc) electropolymer immobilized on a basal plane pyrolytic graphite electrode (BPPGE). SWCNT induces crystallinity on the NiTAPc electropolymeric film structure and increases its apparent electron transfer rate constant ( kapp). We proved that there is potential advantage of using electrode based on the SWCNT- poly-NiTAPc hybrid for catalytic and sensing applications as it enhances the catalytic current for the detection of nitric oxide more than twice compared to bare BPPGE, BPPGE-SWCNT and other electrodes without SWCNTs.

Pillay, Jeseelan; Ozoemena, Kenneth I.



Environmental applications of radiation-induced defects in clay minerals  

NASA Astrophysics Data System (ADS)

Radiation effects on clay minerals have been studied over the last 35 years, providing a wealth of information on environmental and geological processes. They have been applied to the reconstruction of past radioelement migrations in the geosphere, the dating of clay minerals from soils or the evolution of the physico-chemical properties under irradiation. All known radiation-induced point defects in clay minerals are detected using Electron Paramagnetic Resonance Spectroscopy. They mostly consist in electron holes located on oxygen atoms of the structure, and can be differentiated through their nature and their thermal stability. For instance, several are associated to a ? orbital on a Si-O bond. One defect, namely the A-center, is stable over geological periods at ambiant temperature. These point defects are produced mainly by ionizing radiations. By contrast to point defects, it was shown that electron or heavy ion irradiation easily produces amorphization in smectites. Two main applications of radiation-induced defects in clay minerals are derived : (i) the use of defects as tracers of past radioactivity. In geosystems where the age of the clay can be constrained, migrations of radioelements can be reconstructed in natural analogues of the far field of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to laterites of the Amazon basin. (ii) The influence of radiation on clay mineral properties that remains poorly documented, although it is an important issue in various domains such as the safety assessment of the high level nuclear waste repositories. In case of a leakage of transuranic elements from the radioactive wasteform, alpha recoil nuclei would amorphize smectite after a period much lower than the disposal lifetime. By contrast, amorphisation from ionizing radiation is unlikely over 1 million years. Furthermore, it was shown that amorphization greatly enhances the dissolution kinetics of smectite, a result that must be taken into account in the safety assessment of engineered barriers.

Allard, T.



Fiber enriched diets and radiation induced injury of the gut  

Microsoft Academic Search

The aim of this study was to evaluate the effect of fiber-enriched defined formula diets (DFDs) on radiation-induced enteropathy. Forty-five male Sprague-Dawley rats were assigned randomly after abdominal irradiation to one of three groups (15 in each group): a fiber-free DFD group, a non-soluble fiber-enriched DFD group, and a soluble fiber-enriched DFD group. They kept their diets respectively for seven

Murat Kapkac; Mehmet Erikoglu; Pars Tuncyurek; Sinan Ersin; Mustafa Esassolak; Murat Alkanat; Oguz Sipahioglu



Radioprotective effect of silymarin against radiation induced hepatotoxicity  

Microsoft Academic Search

The radioprotective effect of silymarin using different modes of treatment against radiation (3 or 6 Gy) induced hepatotoxicity 1, 3 and 7 days post-irradiation was studied. Whole-body gamma-irradiation revealed an increase in serum alkaline phosphatase (AP) activity as well as liver glutathione reductase (GR) and glutathione peroxidase (GSH-PX) activities on the first post-exposure day with respect to the control value.

Laila A. Ramadan; Hamed M. Roushdy; Gamal M. Abu Senna; Nour E. Amin; Ola A. El-Deshw



Kick velocity induced by magnetic dipole and quadrupole radiation  

Microsoft Academic Search

We examine the recoil velocity induced by the superposition of the magnetic\\u000adipole and quadrupole radiation from a pulsar\\/magnetar born with rapid\\u000arotation. The resultant velocity depends on not the magnitude, but rather the\\u000aratio of the two moments and their geometrical configuration. The model does\\u000anot necessarily lead to high spatial velocity for a magnetar with a strong\\u000amagnetic

Yasufumi Kojimaand; Yugo E. Kato



Thermal and radiation-induced interface traps in MOS devices  

Microsoft Academic Search

The interface trap build-up mechanisms during post-irradiation thermal annealing and radiation-induced charge neutralisation (RICN) are experimentally investigated. The role of substrate electrons is shown to be significant in post-irradiation interface trap build-up. The RICN is found to be incapable to replace a standard thermal annealing test in terms of conservative low dose rate response estimation

A. V. Sogoyan; S. V. Cherepko; V. S. Pershenkov; V. I. Rogov; V. N. Ulimov; V. V. Emelianov



The mechanism of radiation induced densification in fused silica  

NASA Astrophysics Data System (ADS)

In this thesis, deep-UV (193nm) induced densification in fused silica is reviewed and some new compaction data are presented. UV-induced compaction in fused silica obeys a universal relation where, using the total energy absorbed from two-photon absorption as the dose parameter, density changes are equal to a material dependent constant times the dose parameter to a power of about 0.66 (2/3). With the exception of the two-photon damage excitation, this behavior is consistent with the compaction studies using electron beam and gamma radiation, suggesting like densification mechanisms. We have developed a two-phase model to describe the structure of vitreous silica. Low temperature phase A and high temperature phase B are connected by a solid state phase transition and the phase transition temperature should be higher than the glass transition temperature. This model is based on the observed volume change induced by hydrostatic pressure, fast neutron, ion, electron and photon irradiation etc. Using this structural model, we can understand the compaction-fluence behaviors for two distinct compaction phenomena; knock-on (atomic displacement) radiation-induced-compaction and ionization-induced-compaction. Generally, knock-on radiation triggers a A --> B phase transition in vitreous silica. For ionization-induced compaction, we propose a simple bridging-bond relaxation mechanism to explain the observed stretched power (2/3) dependence of compaction on deposited energy for ionization induced compaction in silica. We have used thermal annealing techniques to study the deep ultraviolet-induced compaction in fused silica, and found a strong correlation between the UV-compaction rates and thermal histories among various samples. Experimental observations agree with the predictions based on our compaction model. We have constructed a 193nm interferometer and measured the optical-pathlength difference (OPD) changes from compaction at the actinic wavelength. For the first time, we were able to directly observe the spatial variation of OPD, clearly showing the reduction in OPD outside the damaged region (because of the surface indentation) in contrast to the density-driven OPD increase inside the damaged area. The compaction-induced OPD decreased in thermal annealing and the reduction agreed with our stress-induced birefringence results.

Piao, Fan



Modeling of induced empirical constitutive relations on materials with FCC, BCC, and HCP crystalline structures: severe plastic deformation  

Microsoft Academic Search

In this study, empirical constitutive relations of materials with different crystalline structures through severe plastic\\u000a deformation are introduced. Here, for each material, an optimized empirical relation is chosen by fitting some empirical relations\\u000a on the results achieved from a dislocation-based constitutive model. In this work, four modes of empirical relations are fitted\\u000a on the results of modified Estrin–Toth–Molinari–Brechet constitutive model

Mohsen Kazeminezhad; Ehsan Hosseini



Morphological change of cell-membrane-integrated crystalline structure induced by cell shape change in Euglena gracilis  

Microsoft Academic Search

Summary  Fourier transform and an image filtering technique were used for structural analysis of the pellicular strip inEuglena gracilis. Freeze-fracture images of a two-dimensional crystalline structure in the plasma membrane were taken from elongated and rounded\\u000a cells. Their lattice constants were precisely determined from Fourier transform patterns, and masked filter images were generated.\\u000a Although differences in their lattice constants could not

K. Murata; M. Okamoto; T. Suzaki



DNA Strand Breakage, Thymine Glycol Production, and Hydroxyl Radical Generation Induced by Different Samples of Crystalline Silica in Vitro  

Microsoft Academic Search

Five preparations of ?-quartz [Min-U-Sil 5 (MQZ), MQZ pretreated with hydrofluoric acid (HFMQZ), Chinese standard ?-quartz (CSQZ), and two German samples, DQ-12 and F600] and two preparations of the crystalline silica polymorphs, cristobalite and tridymite, previously characterized for surface area and surface charge, were evaluated for their relative activities in the following assays: (i) in vitro assays of short duration

L. N. Daniel; Y. Mao; T. C. L. Wang; C. J. Markey; S. P. Markey; X. L. Shi; U. Saffiotti



Countermeasures for Space Radiation Induced Malignancies and Acute Biological Effects  

NASA Astrophysics Data System (ADS)

The hypothesis being evaluated in this research program is that control of radiation induced oxidative stress will reduce the risk of radiation induced adverse biological effects occurring as a result of exposure to the types of radiation encountered during space travel. As part of this grant work, we have evaluated the protective effects of several antioxidants and dietary supplements and observed that a mixture of antioxidants (AOX), containing L-selenomethionine, N-acetyl cysteine (NAC), ascorbic acid, vitamin E succinate, and alpha-lipoic acid, is highly effective at reducing space radiation induced oxidative stress in both in vivo and in vitro systems, space radiation induced cytotoxicity and malignant transformation in vitro [1-7]. In studies designed to determine whether the AOX formulation could affect radiation induced mortality [8], it was observed that the AOX dietary supplement increased the 30-day survival of ICR male mice following exposure to a potentially lethal dose (8 Gy) of X-rays when given prior to or after animal irradiation. Pretreatment of animals with antioxidants resulted in significantly higher total white blood cell and neutrophil counts in peripheral blood at 4 and 24 hours following exposure to doses of 1 Gy and 8 Gy. Antioxidant treatment also resulted in increased bone marrow cell counts following irradiation, and prevented peripheral lymphopenia following 1 Gy irradiation. Supplementation with antioxidants in irradiated animals resulted in several gene expression changes: the antioxidant treatment was associated with increased Bcl-2, and decreased Bax, caspase-9 and TGF-?1 mRNA expression in the bone marrow following irradiation. These results suggest that modulation of apoptosis may be mechanistically involved in hematopoietic system radioprotection by antioxidants. Maintenance of the antioxidant diet was associated with improved recovery of the bone marrow following sub-lethal or potentially lethal irradiation. Taken together, oral supplementation with antioxidants appears to be an effective approach for the radioprotection of hematopoietic cells against the cell killing effects of radiation, and for improving survival in irradiated animals. Preliminary data suggest similar antioxidant protective effects for animals exposed to potentially lethal doses of proton radiation. Studies were also performed to determine whether dietary antioxidants could affect the incidence rates of malignancies in CBA mice exposed to 300 cGy proton (1 GeV/n) radiation or 50 cGy iron ion (1 GeV/n) radiation [9]. Two antioxidant formulations were utilized in these studies; an AOX formulation containing the mixture of antioxidant agents developed from our previous studies and an antioxidant dietary formulation containing the soybean-derived protease inhibitor known as the Bowman-Birk inhibitor (BBI). BBI was evaluated in the form of BBI Concentrate (BBIC), which is the form of BBI utilized in human trials. BBIC has been utilized in human trials since 1992, as described [10]. The major finding in the long-term animal studies was that there was a reduced risk of malignant lymphoma in mice exposed to space radiations and maintained on diets containing the antioxidant formulations. In addition, the two different dietary countermeasures also reduced the yields of a variety of different rare tumor types, arising from both epithelial and connective tissue cells, observed in the animals exposed to space radiation. REFERENCES [1] Guan J. et al (2004) Radiation Research 162, 572-579. [2] Wan X.S. et al (2005) Radiation Research 163, 364-368. [3] Wan X.S. et al (2005) Radiation Research 163, 232-240. [4] Guan J. et al (2006) Radiation Research 165, 373-378. [5] Wan X.S. et al (2006) International Journal of Radiation Oncology, Biology, Physics 64, 1475-1481. [6] Kennedy A.R. et al (2006) Radiation Research 166, 327-332. [7] Kennedy A.R. et al (2007) Radiation & Environmental Biophysics 46(2), 201-3. [8]Wambi, C., Sanzari, J., Wan, X.S., Nuth, M., Davis, J., Ko, Y.-H., Sayers, C.M., Baran, M., Ware, J.H. and Kennedy, A

Kennedy, Ann


Radiation induced CNS toxicity - molecular and cellular mechanisms  

PubMed Central

Radiotherapy of tumours proximal to normal CNS structures is limited by the sensitivity of the normal tissue. Prior to the development of prophylactic strategies or treatment protocols a detailed understanding of the mechanisms of radiation induced CNS toxicity is mandatory. Histological analysis of irradiated CNS specimens defines possible target structures prior to a delineation of cellular and molecular mechanisms. Several lesions can be distinguished: Demyelination, proliferative and degenerative glial reactions, endothelial cell loss and capillary occlusion. All changes are likely to result from complex alterations within several functional CNS compartments. Thus, a single mechanism responsible cannot be separated. At least four factors contribute to the development of CNS toxicity: (1) damage to vessel structures; (2) deletion of oligodendrocyte-2 astrocyte progenitors (O-2A) and mature oligodendrocytes; (3) deletion of neural stem cell populations in the hippocampus, cerebellum and cortex; (4) generalized alterations of cytokine expression. Several underlying cellular and molecular mechanisms involved in radiation induced CNS toxicity have been identified. The article reviews the currently available data on the cellular and molecular basis of radiation induced CNS side effects. ?? © 2001 Cancer Research Campaign

Belka, C; Budach, W; Kortmann, R D; Bamberg, M



Long-term effects of pulsed KrF laser radiation on crystalline and amorphous SiO2  

NASA Astrophysics Data System (ADS)

At the 1992 Boulder DAmage Symposium, we reported test results for 6 fused silica glass types exposed to millions of KrF laser pulses at a fluence of 500 mJ/cm2 and a pulse repetition rate of 300 Hz. The peculiar results and the big variations between glass types (`slow' relaxing vs. `fast' relaxing glass families) were interpreted as being due to subtle differences in the glass microstructure induced by the homogenization and heat treatments, but no detailed explanation could be offered. As a small step toward improving our understanding, we have expanded our studies to include four additional glass types: Suprasil 300 (S300) and Suprasil 311 (S311) from Heraeus, and conventional 7940 and a new Excimer-grade fused silica from Corning.

Krajnovich, Douglas J.; Pour, Iraj K.



?B-crystallin/HspB5 regulates endothelial-leukocyte interactions by enhancing NF-?B-induced up-regulation of adhesion molecules ICAM-1, VCAM-1 and E-selectin.  


?B-crystallin is a small heat shock protein, which has pro-angiogenic properties by increasing survival of endothelial cells and secretion of vascular endothelial growth factor A. Here we demonstrate an additional role of ?B-crystallin in regulating vascular function, through enhancing tumor necrosis factor ? (TNF-?) induced expression of endothelial adhesion molecules involved in leukocyte recruitment. Ectopic expression of ?B-crystallin in endothelial cells increases the level of E-selectin expression in response to TNF-?, and enhances leukocyte-endothelial interaction in vitro. Conversely, TNF-?-induced expression of intercellular adhesion molecule 1, vascular cell adhesion molecule 1 and E-selectin is markedly inhibited in endothelial cells isolated from ?B-crystallin-deficient mice. This is associated with elevated levels of I?B in ?B-crystallin deficient cells and incomplete degradation upon TNF-? stimulation. Consistent with this, endothelial adhesion molecule expression is reduced in inflamed vessels of ?B-crystallin deficient mice, and leukocyte rolling velocity is increased. Our data identify ?B-crystallin as a new regulator of leukocyte recruitment, by enhancing pro-inflammatory nuclear factor ? B-signaling and endothelial adhesion molecule expression during endothelial activation. PMID:23929007

Dieterich, Lothar C; Huang, Hua; Massena, Sara; Golenhofen, Nikola; Phillipson, Mia; Dimberg, Anna



Targets for, and consequences of, radiation-induced chromosomal instability  

NASA Astrophysics Data System (ADS)

Chromosomal instability has been demonstrated in a human- hamster hybrid cell line, GM10115, after exposure to x- rays. Chromosomal instability in these cells is characterized by the appearance of novel chromosomal rearrangements multiple generations after exposure to ionizing radiation. To identify the cellular target(s) for radiation-induced chromosomal instability, cells were treated with 125I-labeled compounds. Labeling cells with 125I-iododeoxyuridine, which caused radiation damage to the DNA and associated nuclear structures, did induce chromosomal instability. While cell killing and first-division chromosomal rearrangements increased with increasing numbers of 125I decays, the frequency of chromosomal instability was independent of dose. Incorporation of an 125I-labeled protein, 125I-succinyl- concanavalin A, into either the plasma membrane or the cytoplasm, failed to elicit chromosomal instability. These results show that radiation damage to the nucleus, and not to extranuclear regions, contributes to the induction of chromosomal instability. To determine the role of DNA strand breaks as a molecular lesion responsible for initiating chromosomal instability, cells were treated with a variety of DNA strand breaking agents. Agents capable of producing complex DNA double strand breaks, including X-rays, Neocarzinostatin and bleomycin, were able to induce chromosomal instability. In contrast, double strand breaks produced by restriction endonucleases as well as DNA strand breaks produced by hydrogen peroxide failed to induce chromosomal instability. This demonstrates that the type of DNA breakage is important in the eventual manifestation of chromosomal instability. In order to understand the relationship between chromosomal instability and other end points of genomic instability, chromosomally stable and unstable clones were analyzed for sister chromatid exchange, delayed reproductive cell death, delayed mutation, mismatch repair and delayed gene amplification. Although individual clones within each group were significantly different from unirradiated clones for many of the endpoints, there was no significant correlation between chromosomal instability and the phenotypes of sister chromatid exchange, delayed mutation, and mismatch repair. Delayed gene amplification weakly correlated chromosomal instability (0.05 < p < 0.1) and delayed reproductive cell death correlated strongly (p < 0.05) with chromosomal instability. These data indicate that multiple pathways exist for inducing genomic instability in GM10115 cells after radiation exposure.

Kaplan, Mark Isaac


Quantifying Local Radiation-Induced Lung Damage From Computed Tomography  

SciTech Connect

Purpose: Optimal implementation of new radiotherapy techniques requires accurate predictive models for normal tissue complications. Since clinically used dose distributions are nonuniform, local tissue damage needs to be measured and related to local tissue dose. In lung, radiation-induced damage results in density changes that have been measured by computed tomography (CT) imaging noninvasively, but not yet on a localized scale. Therefore, the aim of the present study was to develop a method for quantification of local radiation-induced lung tissue damage using CT. Methods and Materials: CT images of the thorax were made 8 and 26 weeks after irradiation of 100%, 75%, 50%, and 25% lung volume of rats. Local lung tissue structure (S{sub L}) was quantified from local mean and local standard deviation of the CT density in Hounsfield units in 1-mm{sup 3} subvolumes. The relation of changes in S{sub L} (DELTAS{sub L}) to histologic changes and breathing rate was investigated. Feasibility for clinical application was tested by applying the method to CT images of a patient with non-small-cell lung carcinoma and investigating the local dose-effect relationship of DELTAS{sub L}. Results: In rats, a clear dose-response relationship of DELTAS{sub L} was observed at different time points after radiation. Furthermore, DELTAS{sub L} correlated strongly to histologic endpoints (infiltrates and inflammatory cells) and breathing rate. In the patient, progressive local dose-dependent increases in DELTAS{sub L} were observed. Conclusion: We developed a method to quantify local radiation-induced tissue damage in the lung using CT. This method can be used in the development of more accurate predictive models for normal tissue complications.

Ghobadi, Ghazaleh; Hogeweg, Laurens E. [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Faber, Hette [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Tukker, Wim G.J. [Department of Radiology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Schippers, Jacobus M. [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Accelerator Department, Paul Scherrer Institut, Villigen (Switzerland); Brandenburg, Sytze [Kernfysisch Versneller Instituut, Groningen (Netherlands); Langendijk, Johannes A. [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Coppes, Robert P. [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Department of Cell Biology, Section of Radiation and Stress Cell Biology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands); Luijk, Peter van, E-mail: p.van.luijk@rt.umcg.n [Department of Radiation Oncology, University Medical Center Groningen/University of Groningen, Groningen (Netherlands)



Simultaneous broadband light trapping and fill factor enhancement in crystalline silicon solar cells induced by Ag nanoparticles and nanoshells.  


Crystalline silicon solar cells are predominant and occupying more than 89% of the global solar photovoltaic market. Despite the boom of the innovative solar technologies, few can provide a low-cost radical solution to dramatically boost the efficiency of crystalline silicon solar cells, which has reached plateau in the past ten years. Here, we present a novel strategy to simultaneously achieve dramatic enhancement in the short-circuit current and the fill factor through the integration of Ag plasmonic nanoparticles and nanoshells on the antireflection coating and the screen-printed fingers of monocrystalline silicon solar cells, respectively, by a single step and scalable modified electroless displacement method. As a consequence, up to 35.2% enhancement in the energy conversion efficiency has been achieved due to the plasmonic broadband light trapping and the significant reduction in the series resistance. More importantly, this method can further increase the efficiency of the best performing textured solar cells from 18.3% to 19.2%, producing the highest efficiency cells exceeding the state-of-the-art efficiency of the standard screen-printed solar cells. The dual functions of the Ag nanostructures, reported for the first time here, present a clear contrast to the previous works, where plasmonic nanostructures were integrated into solar cells to achieve the short-circuit current enhancement predominately. Our method offers a facile, cost-effective and scalable pathway for metallic nanostructures to be used to dramatically boost the overall efficiency of the optically thick crystalline silicon solar cells. PMID:23037536

Fahim, Narges F; Jia, Baohua; Shi, Zhengrong; Gu, Min



Sensitivity to Radiation-Induced Cancer in Hemochromatosis  

SciTech Connect

The objectives of this pilot project using HFE-knockout homozygotes and heterozygotes are to (1) determine whether the knock-out mice have greater sensitivity to radiation-induced cancer of the colon, liver and breast, (2) establish the dependence of this sensitivity on the accumulation of iron, (3) determine the extent to which cell replication and apoptosis occur in these target tissues with varying iron load, and (4) correlate the increases in sensitivity with changes in insulin-related signaling in tumors and normal tissue from each target organ. Three experimental designs will be used in the pilot project. The sequence of experiments is designed to first explore the influence of iron load on the response and demonstrate that HFE knockout mice are more sensitive than the wild type to radiation-induced cancer in one or more of three target tissues (liver, colon and breast). The dose response relationships with a broader set of radiation doses will be explored in the second experiment. The final experiment is designed to explore the extent to which heterozygotes display the increased susceptibility to cancer induction and to independently assess the importance of iron load to the initiation versus promotion of tumors.

Bull. Richard J.; Anderson, Larry E.



Space-radiation-induced photon luminescence of the Moon  

NASA Astrophysics Data System (ADS)

We report on the results of a continuing study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. Understanding the space radiation environment is critical to future exploration of the Moon, and this includes photons. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This surface model then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) or Solar Particle Events (SPEs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon's surface when there is no sunlight and Earthshine. The result is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to aid future orbiting instrumentation in the measurement of various components of the space-radiation-induced photon luminescence present on the Moon.

Lee, K. T.; Wilson, T. L.



G2-chromosome aberrations induced by high-LET radiations  

NASA Astrophysics Data System (ADS)

We report measurements of initial G2-chromatid breaks in normal human fibroblasts exposed to various types of high-LET particles. Exponentially growing AG 1522 cells were exposed to ?-rays or heavy ions. Chromosomes were prematurely condensed by calyculin A. Chromatid-type breaks and isochromatid-type breaks were scored separately. The dose response curves for the induction of total chromatid breaks (chromatid-type + isochromatid-type) and chromatid-type breaks were linear for each type of radiation. However, dose response curves for the induction of isochromatid-type breaks were linear for high-LET radiations and linear-quadratic for ?-rays. Relative biological effectiveness (RBE), calculated from total breaks, showed a LET dependent tendency with a peak at 55 keV/?m silicon (2.7) or 80 keV/?m carbon (2.7) and then decreased with LET (1.5 at 440 keV/?m). RBE for chromatid-type break peaked at 55 keV/?m (2.4) then decreased rapidly with LET. The RBE of 440 keV/?m iron particles was 0.7. The RBE calculated from induction of isochromatid-type breaks was much higher for high-LET radiations. It is concluded that the increased production of isochromatid-type breaks, induced by the densely ionizing track structure, is a signature of high-LET radiation exposure.

Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Ito, H.; Wu, H.; Cucinotta, F. A.


Radiation-induced Cancer Risk from Annual Computed Tomography for Patients with Cystic Fibrosis  

Microsoft Academic Search

Rationale: Computed tomography (CT) is being considered as a tool for routine monitoring of lung damage in people with cystic fibrosis. Concern has been raised, however, about the associated risk of radiation-induced cancer. Objectives: To estimate the risk of radiation-induced cancer from lung CT for patients with cystic fibrosis, assuming annual monitoring start- ing at age 2 years. Methods: Radiation

Amy Berrington de Gonzalez; Kwang Pyo Kim; Jonathan M. Samet



Involvement of Prostaglandins and Histamine in Radiation-Induced Temperature Responses in Rats.  

National Technical Information Service (NTIS)

Exposure of rats to Gy of gamma radiation induced hypothermia, whereas exposure to 20-150 Gy produced hypothermia. Since radiation exposure included the release of prostaglandins (PGs) and histamine, the role of PGs and histamine in radiation-induced temp...

S. B. Kandasamy W. A. Hunt



TransDifferentiation of Neural Stem Cells: A Therapeutic Mechanism Against the Radiation Induced Brain Damage  

Microsoft Academic Search

Radiation therapy is an indispensable therapeutic modality for various brain diseases. Though endogenous neural stem cells (NSCs) would provide regenerative potential, many patients nevertheless suffer from radiation-induced brain damage. Accordingly, we tested beneficial effects of exogenous NSC supplementation using in vivo mouse models that received whole brain irradiation. Systemic supplementation of primarily cultured mouse fetal NSCs inhibited radiation-induced brain atrophy

Kyeung Min Joo; Juyoun Jin; Bong Gu Kang; Se Jeong Lee; Kang Ho Kim; Heekyoung Yang; Young-Ae Lee; Yu Jin Cho; Yong-Seok Im; Dong-Sup Lee; Do-Hoon Lim; Dong Hyun Kim; Hong-Duck Um; Sang-Hun Lee; Jung-II Lee; Do-Hyun Nam



Large angle hadron correlations from medium-induced gluon radiation  

NASA Astrophysics Data System (ADS)

Final state medium-induced gluon radiation in ultradense nuclear matter is examined and shown to favor large angle emission when compared to vacuum bremsstrahlung due to the suppression of collinear gluons. Perturbative expression for the contribution of its hadronic fragments to the back-to-back particle correlations is derived. It is found that in the limit of large jet energy loss gluon radiation determines the yield and angular distribution of |??|??2 dihadrons to high transverse momenta pT_2 of the associated particles. Clear transition from enhancement to suppression of the away-side hadron correlations is established at moderate pT_2 and its experimentally accessible features are predicted versus the trigger particle momentum pT_1. On September 25, 2005, my advisor, friend and colleague Ventseslav Rizov passed away. With his untimely death the Bulgarian physics community lost a person of great kindness, integrity and devotion to science. This work is dedicated to his memory.

Vitev, Ivan



Radiation induced grafting of acrylic acid onto extruded polystyrene surface  

NASA Astrophysics Data System (ADS)

Polystyrene materials with good solubility in liquid scintillation cocktails are used to wipe off different types of surfaces in order to determine the tritium removable contamination with the help of a liquid scintillation counter. This paper analyses hydrophilic surface modifications by radiation induced grafting of acrylic groups onto extruded polystyrene plates. Two grafting methods were used: (a) exposure of extruded polystyrene plates, immersed in aqueous acrylic acid solution, to a gamma radiation of a Co-60 source, and (b) exposure of extruded polystyrene plates to a Co-60 source, followed by the immersion of extruded polystyrene plates in aqueous acrylic acid solution. The grafting of acrylic was proved by IR spectrometry and by radiometric methods using acrylic acid labelled with tritium.

Fugaru, Viorel; Bubueanu, George; Tuta, Catalin



Treatment of radiation- and chemotherapy-induced stomatitis  

SciTech Connect

Severe stomatitis is a common problem encountered during either radiation therapy or chemotherapy. Most therapeutic regimens are empirical, with no scientific basis. The purpose of this study is to determine the efficacy of various topical solutions in the treatment of radiation- or chemotherapy-induced stomatitis. Eighteen patients were entered into a prospective double-blinded study to test several topical solutions: (1) viscous lidocaine with 1% cocaine; (2) dyclonine hydrochloride 1.0% (Dyclone); (3) kaolin-pectin solution, diphenhydramine plus saline (KBS); and (4) a placebo solution. Degree of pain relief, duration of relief, side effects, and palatability were evaluated. The results showed that Dyclone provided the most pain relief. Dyclone and viscous lidocaine with 1% cocaine provided the longest pain relief, which averaged 50 minutes This study provides objective data and defines useful guidelines for treatment of stomatitis.

Carnel, S.B.; Blakeslee, D.B.; Oswald, S.G.; Barnes, M. (Fitzsimons Army Medical Center, Aurora, CO (USA))



Radiation-induced transient absorption in optical fibers  

SciTech Connect

Transient absorption in optical fibers has been studied with emphasis on fast absorption components. Radiation damage was induced with a Febetron 706 electron accelerator, modified to deliver an electron pulse width of 1.1 ns. Dye lasers were synchronized to the accelerator to provide a light pulse through the fiber during the radiation pulse. The output light pulse was detected with a biplanar vacuum photodiode. Four scope traces were used on each electron pulse to monitor the Febetron output, the input drive pulse, and two records of the output pulse on two sweep speeds. Detailed data were acquired for times less than 100 ns after irradiation. An insulated enslosure was used to vary fiber temperature from -30/sup 0/C to + 250/sup 0/C. Several fibers were studied with emphasis on ITT T303 PCS fiber. Data were acquired at 600 and 850 nm. Theoretical modeling of the data is presented.

Looner, L.D.; Turquet de Beauregard, G.; Lyons, P.B.; Kelly, R.E.



Genomic Instability Induced by High and Low Let Ionizing Radiation  

NASA Astrophysics Data System (ADS)

Genomic instability is the increased rate of acquisition of alterations in the mammalian genome, and includes such diverse biological endpoints as chromosomal destabilization, aneuploidy, micronucleus formation, sister chromatid exchange, gene mutation and amplification, variations in colony size, reduced plating efficiency, and cellular transformation. Because these multiple endpoints persist long after initial radiation exposure, genomic instability has been proposed to operate as a driving force contributing to genetic plasticity and carcinogenic potential. Many of these radiation-induced endpoints depend qualitatively and quantitatively on genetic background, dose and LET. Differences in the frequency and temporal expression of chromosomal instability depend on all three of the foregoing factors. On the other hand, many of these endpoints appear independent of dose and show bystander effects, implicating non-nuclear targets and epigenetic regulatory mechanisms. The present work will survey results concerning the LET dependence of genomic instability and the role of epigenetic mechanisms, with a particular emphasis on the endpoint of chromosomal in tability

Limoli, C. L.; Ponnaiya, B.; Corcoran, J. J.; Giedzinski, E.; Kaplan, M. I.; Hartmann, A.; Morgan, W. F.


Cerenkov emission induced by external beam radiation stimulates molecular fluorescence  

PubMed Central

Purpose: Cerenkov emission is induced when a charged particle moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons in everyday radiation therapy of tissue; yet, this phenomenon has never been fully documented. This study quantifies the emissions and also demonstrates that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms.Methods: In this study, Cerenkov emission induced by radiation from a clinical linear accelerator is investigated. Biological mimicking phantoms were irradiated with x-ray photons, with energies of 6 or 18 MV, or electrons at energies 6, 9, 12, 15, or 18 MeV. The Cerenkov emission and the induced molecular fluorescence were detected by a camera or a spectrometer equipped with a fiber optic cable.Results: It is shown that both x-ray photons and electrons, at MeV energies, produce optical Cerenkov photons in tissue mimicking media. Furthermore, we demonstrate that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms.Conclusions: The results here indicate that molecular fluorescence monitoring during external beam radiotherapy is possible.

Axelsson, Johan; Davis, Scott C.; Gladstone, David J.; Pogue, Brian W.



Reversible phase transitions in polymer gels induced by radiation forces.  


Many polymer gels undergo reversible, discontinuous volume changes in response to changes in the balance between repulsive intermolecular forces that act to expand the polymer network and attractive forces that act to shrink it. Repulsive forces are usually electrostatic or hydrophobic in nature, whereas attraction is mediated by hydrogen bonding or van der Waals interactions. The competition between these counteracting forces, and hence the gel volume, can thus be controlled by subtle changes in parameters such as pH (ref. 4), temperature, solvent composition or gel composition. Here we describe a more direct influence on this balance of forces, by showing that the radiation force generated by a focused laser beam induces reversible shrinkage in polymer gels. Control experiments confirm that the laser-induced volume phase transitions are due to radiation forces, rather than local heating, modifying the weak interactions in the gels, in agreement with previous observations of light-induced chain association in polymer solutions. We find that, owing to shear-relaxation processes, gel shrinkage occurs up to several tens of micrometres away from the irradiation spot, raising the prospect that the combination of stimuli-responsive polymer gels and laser light might lead to new gel-based systems for applications such as actuating or sensing. PMID:11089966

Juodkazis, S; Mukai, N; Wakaki, R; Yamaguchi, A; Matsuo, S; Misawa, H



Cerenkov emission induced by external beam radiation stimulates molecular fluorescence  

SciTech Connect

Purpose: Cerenkov emission is induced when a charged particle moves faster than the speed of light in a given medium. Both x-ray photons and electrons produce optical Cerenkov photons in everyday radiation therapy of tissue; yet, this phenomenon has never been fully documented. This study quantifies the emissions and also demonstrates that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Methods: In this study, Cerenkov emission induced by radiation from a clinical linear accelerator is investigated. Biological mimicking phantoms were irradiated with x-ray photons, with energies of 6 or 18 MV, or electrons at energies 6, 9, 12, 15, or 18 MeV. The Cerenkov emission and the induced molecular fluorescence were detected by a camera or a spectrometer equipped with a fiber optic cable. Results: It is shown that both x-ray photons and electrons, at MeV energies, produce optical Cerenkov photons in tissue mimicking media. Furthermore, we demonstrate that the Cerenkov emission can excite a fluorophore, protoporphyrin IX (PpIX), embedded in biological phantoms. Conclusions: The results here indicate that molecular fluorescence monitoring during external beam radiotherapy is possible.

Axelsson, Johan; Davis, Scott C.; Gladstone, David J.; Pogue, Brian W. [Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755 (United States); Norris Cotton Cancer Center, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03766 (United States); Thayer School of Engineering and Department of Physics and Astronomy, Dartmouth College, Hanover, New Hampshire 03755 (United States)



Radiation effects in ice: New results  

NASA Astrophysics Data System (ADS)

Studies of radiation effects in ice are motivated by intrinsic interest and by applications in astronomy. Here we report on new and recent results on radiation effects induced by energetic ions in ice: amorphization of crystalline ice, compaction of microporous amorphous ice, electrostatic charging and dielectric breakdown and correlated structural/chemical changes in the irradiation of water ammonia ices.

Baragiola, R. A.; Famá, M.; Loeffler, M. J.; Raut, U.; Shi, J.



DNA damage induced by the direct effect of radiation  

NASA Astrophysics Data System (ADS)

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.

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



Radiation-induced luminescence in magnesium aluminate spinel crystals and ceramics  

NASA Astrophysics Data System (ADS)

Radioluminescence (RL) and thermoluminescence (TL) in spinel crystals and ceramics were investigated to elucidate the radiation-induced electronic processes in single crystals grown by Verneuil and Czochralski methods as well as transparent and translucent ceramics. Both RL and TL spectra demonstrate a UV-band related to electron hole recombination luminescence at intrinsic defects; green and red luminescence are identified with emission of Mn2+- and Cr3+-ions, respectively. The kinetics of growth of different RL luminescence bands depending on dose at the prolonged X-irradiation shows the competitive character of charge and energy transfer between defects and impurity ions. The dependence of RL intensity on the temperature of the sample was measured in the range of 300 750 K and compared with TL for different emission bands. The variety of maxima in the temperature dependence of RL and in the glow curves of TL measured for different luminescence bands in spinels of different origins and crystalline forms is used to show that charge carrier traps and luminescence centers are not isolated defects but are complexes of defects and impurities. The formation, structure and properties of these complexes depend on the processing conditions.

Gritsyna, V. T.; Kazarinov, Yu. G.; Kobyakov, V. A.; Reimanis, I. E.



Facial reconstruction for radiation-induced skin cancer  

SciTech Connect

Radiation-induced skin cancers can be difficult to diagnose and treat. Typically, a patient who has received orthovoltage radiotherapy for disorders such as acne, eczema, tinea capitis, skin tuberculosis, and skin cancer can expect that aggressive skin cancers and chronic radiodermatitis may develop subsequently. Cryptic facial cancers can lead to metastases and death. Prophylactic widefield excision of previously irradiated facial skin that has been subject to multiple recurrent skin cancers is suggested as a method of deterring future cutaneous malignancy and metastases. The use of tissue expanders and full-thickness skin grafts offers an expedient and successful method of subsequent reconstruction.

Panje, W.R.; Dobleman, T.J. (Univ. of Chicago, IL (USA))



Functionalization of carbon nanotubes by radiation-induced graft polymerization.  


Multi-walled carbon nanotubes (MWCNTs) were functionalized by radiation-induced graft polymerization of acrylic acid onto the surface of MWCNTs in order to improve their dispersibility in water. 1H NMR, Raman spectroscopy, TEM, and TGA techniques were used to characterize the resulting functionalized MWCNTs. The grafting degree was dependent on the grafting conditions such as the absorbed dose and the monomer concentration. The experimental results confirmed that poly(acrylic acid) chains were successfully grafted onto the surface of the MWCNTs. The poly(acrylic acid)-grafted MWCNTs showed a much better water dispersibility than the pristine MWCNTs. PMID:19908742

Jung, Chan-Hee; Kim, Dong-Ki; Choi, Jae-Hak; Shin, Kwanwoo; Nho, Young-Chang; Suh, Dong-Hack



Quantitative analysis of radiation-induced disorder in spinel crystals  

NASA Astrophysics Data System (ADS)

Structural defects in the surface region of magnesium aluminate spinel (MgAl2O4) crystals irradiated with 450 MeV Xe ions were analyzed by using 4He backscattering in channeling geometry (RBS/C). Monte-Carlo simulations applied for the interpretation of channeling spectra permitted to determine the concentration of radiation-induced defects. They showed that the defect distributions are depth dependent, likely due to annihilation of defects at the surface of the crystals. The cross-section for the formation of defects by swift Xe ions, and consequently the diameter of an ion track, were estimated using single-impact-model calculations.

Thomé, L.; Jagielski, J.; Gentils, A.; Nowicki, L.; Garrido, F.



Management of radiation-induced accelerated carotid atherosclerosis  

SciTech Connect

Patients with long survival following cervical irradiation are at risk for accelerated carotid atherosclerosis. The neurologic presentation in these patients mimics naturally occurring atheromatous disease, but patients often present at younger ages and with less concurrent coronary or systemic vascular disease. Hypercholesterolemia also contributes to this accelerated arteriosclerosis. Angiographic findings in this disorder include disproportionate involvement of the distal common carotid artery and unusually long carotid lesions. Pathologic findings include destruction of the internal elastic lamina and replacement of the normal intima and media with fibrous tissue. This article describes two surgical patients with radiation-induced accelerated carotid atherosclerosis who typify the presentation and characteristics of this disease.

Loftus, C.M.; Biller, J.; Hart, M.N.; Cornell, S.H.; Hiratzka, L.F.



Measurements of prompt radiation induced conductivity of Kapton.  

SciTech Connect

We performed measurements of the prompt radiation induced conductivity in thin samples of Kapton (polyimide) at the Little Mountain Medusa LINAC facility in Ogden, UT. Three mil samples were irradiated with a 0.5 {mu}s pulse of 20 MeV electrons, yielding dose rates of 1E9 to 1E10 rad/s. We applied variable potentials up to 2 kV across the samples and measured the prompt conduction current. Analysis rendered prompt conductivity coefficients between 6E-17 and 2E-16 mhos/m per rad/s, depending on the dose rate and the pulse width.

Preston, Eric F. (ITT Corporation, Colorado Springs, CO); Zarick, Thomas Andrew; Sheridan, Timothy J.; Hartman, E. Frederick; Stringer, Thomas Arthur (ITT Corporation, Colorado Springs, CO)



Transient radiation-induced absorption in laser materials  

SciTech Connect

Transient radiation-induced absorption losses in laser materials have been measured using a pulsed nuclear reactor. Reactor pulse widths of 70 to 90 {mu}s and absorbed doses of 1 to 7.5 krad have been used. Transmission recovery times and peak absorption coefficients are given. Materials tested include LiNbO{sub 3}, GSGG, silica substrates, and filter glasses used in the laser cavity. The filter glasses are tested at discrete wavelengths in the range 440--750 nm. Lithium niobate , MgO doped LiNbO{sub 3}, GSGG, and the silica substrates are tested at 1061 nm.

Brannon, P.J.



Radiation therapy induces the DNA damage response in peripheral blood  

PubMed Central

Stereotactic body radiation therapy (SBRT) is a radiotherapy modality that delivers highly conformal, ablative doses to a well-defined target. Here, using a semiquantitative multiplexed assay to analyze ATM and H2AX phosphorylation, we show that ATM kinase activity in peripheral blood mononuclear cells is induced following SBRT. This observation of a systemic ATM kinase-dependent DNA damage response in the peripheral blood is unprecedented and promotes the use of ATM serine-1981 phosphorylation as a predictive biomarker for DNA damaging modalities and ATM inhibitors.

Bakkenist, Christopher J.; Czambel, R. Kenneth; Clump, David A.; Greenberger, Joel S.; Beumer, Jan H.; Schmitz, John C.



X-radiation-induced differentiation of xenotransplanted human undifferentiated rhabdomyosarcoma  

SciTech Connect

A serially xenotransplantable strain of undifferentiated embryonal rhabdomyosarcoma originating from the nasal cavity of a 42-year-old woman has been established in our laboratory. After radiotherapy for the tumor donor, distinct rhabdomyoblastic differentiation of the undifferentiated sarcoma cells appeared in the primary lesion, and it is a reasonable assumption that X-irradiation has a certain potentiality to induce morphologic differentiation of tumor cells. To study this possibility, tissue fragments of undifferentiated embryonal rhabdomyosarcoma that had grown to more than 10 mm after being transplanted to nude mice were selectively irradiated in situ. The degree of rhabdomyoblastic differentiation according to radiation dose was evaluated by light and electron microscopy and by immunostainability for myoglobin, creatine phosphokinase-MM, and desmin. Distinct morphologic differentiation of undifferentiated sarcoma cells could be induced by repeated X-irradiations at several-week intervals.

Takizawa, T.; Matsui, T.; Maeda, Y.; Okabe, S.; Mochizuki, M.; Tanaka, A.; Kawaguchi, K.; Fukayama, M.; Funata, N.; Koike, M.



Site-specific, synchrotron radiation induced surface photochemistry  

SciTech Connect

This paper discusses recent research directed at understanding the nature of surface photochemistry driven by soft x-ray synchrotron radiation (SR). The research is motivated by the potential of x-rays for both high spatial resolution and site specificity. Although a number of systems indicate the potential for site specificity, the authors chose to study the system of SiF{sub 4}/Ge because the adsorbate`s photoabsorption spectrum is rich in structure near the Si 2p threshold (106 eV) while that of the substrate is structureless. This allows them to differentiate substrate-induced effects from those of the adsorbate. By performing time-dependent measurements of the changes induced in the photoemission spectra by SR, they have found that this system`s photochemistry is site-specific in the Si 2p region and have also determined the nature of the products produced by the reaction.

Rosenberg, R.A. [Argonne National Lab., IL (United States). Advanced Photon Source; Simons, J.K.; Frigo, S.P. [Univ. of Wisconsin, Stoughton, WI (United States)



Galactic cosmic ray-induced radiation dose on terrestrial exoplanets.  


Abstract This past decade has seen tremendous advancements in the study of extrasolar planets. Observations are now made with increasing sophistication from both ground- and space-based instruments, and exoplanets are characterized with increasing precision. There is a class of particularly interesting exoplanets that reside in the habitable zone, which is defined as the area around a star where the planet is capable of supporting liquid water on its surface. Planetary systems around M dwarfs are considered to be prime candidates to search for life beyond the Solar System. Such planets are likely to be tidally locked and have close-in habitable zones. Theoretical calculations also suggest that close-in exoplanets are more likely to have weaker planetary magnetic fields, especially in the case of super-Earths. Such exoplanets are subjected to a high flux of galactic cosmic rays (GCRs) due to their weak magnetic moments. GCRs are energetic particles of astrophysical origin that strike the planetary atmosphere and produce secondary particles, including muons, which are highly penetrating. Some of these particles reach the planetary surface and contribute to the radiation dose. Along with the magnetic field, another factor governing the radiation dose is the depth of the planetary atmosphere. The higher the depth of the planetary atmosphere, the lower the flux of secondary particles will be on the surface. If the secondary particles are energetic enough, and their flux is sufficiently high, the radiation from muons can also impact the subsurface regions, such as in the case of Mars. If the radiation dose is too high, the chances of sustaining a long-term biosphere on the planet are very low. We have examined the dependence of the GCR-induced radiation dose on the strength of the planetary magnetic field and its atmospheric depth, and found that the latter is the decisive factor for the protection of a planetary biosphere. Key Words: Radiation-Radiation physics-Habitability-Habitable zone-Planetary atmospheres. Astrobiology 13, 910-919. PMID:24143867

Atri, Dimitra; Hariharan, B; Grießmeier, Jean-Mathias



Strain-induced macroscopic magnetic anisotropy from smectic liquid-crystalline elastomer-maghemite nanoparticle hybrid nanocomposites.  


We combine tensile strength analysis and X-ray scattering experiments to establish a detailed understanding of the microstructural coupling between liquid-crystalline elastomer (LCE) networks and embedded magnetic core-shell ellipsoidal nanoparticles (NPs). We study the structural and magnetic re-organization at different deformations and NP loadings, and the associated shape and magnetic memory features. In the quantitative analysis of a stretching process, the effect of the incorporated NPs on the smectic LCE is found to be prominent during the reorientation of the smectic domains and the softening of the nanocomposite. Under deformation, the soft response of the nanocomposite material allows the organization of the nanoparticles to yield a permanent macroscopically anisotropic magnetic material. Independent of the particle loading, the shape-memory properties and the smectic phase of the LCEs are preserved. Detailed studies on the magnetic properties demonstrate that the collective ensemble of individual particles is responsible for the macroscopic magnetic features of the nanocomposite. PMID:23677459

Haberl, Johannes M; Sánchez-Ferrer, Antoni; Mihut, Adriana M; Dietsch, Hervé; Hirt, Ann M; Mezzenga, Raffaele



Molecular-dynamics simulations of stacking-fault-induced dislocation annihilation in prestrained ultrathin single-crystalline copper films  

SciTech Connect

We report results of large-scale molecular-dynamics simulations of dynamic deformation under biaxial tensile strain of prestrained single-crystalline nanometer-scale-thick face-centered cubic (fcc) copper films. Our results show that stacking faults, which are abundantly present in fcc metals, may play a significant role in the dissociation, cross slip, and eventual annihilation of dislocations in small-volume structures of fcc metals. The underlying mechanisms are mediated by interactions within and between extended dislocations that lead to annihilation of Shockley partial dislocations or formation of perfect dislocations. Our findings demonstrate dislocation starvation in small-volume structures with ultrathin film geometry, governed by a mechanism other than dislocation escape to free surfaces, and underline the significant role of geometry in determining the mechanical response of metallic small-volume structures.

Kolluri, Kedarnath; Gungor, M. Rauf; Maroudas, Dimitrios [Department of Chemical Engineering, University of Massachusetts, Amherst, Massachusetts 01003-3110 (United States)



Risk estimates for radiation-induced cancer and radiation protection standards  

SciTech Connect

At low doses, the primary biological effects of concern are stochastic in nature, i.e., they are more probable at higher doses, but their severity is independent of the dose. In the last decade, a new epidemiological information on radiation-induced cancer in humans has become available. In the Japanese survivors three new cycles of data (11 yr of experience) have accumulated, and a revised dosimetry system (DS86) has been introduced. UNSCEAR (United Nations Scientific Committee on the Effects of Atomic Radiation) reevaluated the risk of cancer from all human sources, which include other human populations such as those treated for ankylosing spondylitis and for cancer of the cervix. UNSCEAR has also evaluated the cancer risk for each of nine organs. For radiation protection purposes (low doses and dose rates, adult populations mainly), nominal values of risk since the 1977-80 period have been {approximately}1%/Sv. This value will need to be increased in the light of the new estimates. Also, risk estimates for various tissues must be reconsidered, and weighting factors used by International Commission on Radiological Protection need to be reexamined. Recommendations on occupational and public dose limits must also be reconsidered. The National Council on Radiation Protection and Measurements is in a comparatively good position with a recently produced set of recommendations that had higher cancer risk estimates in mind.

Sinclair, W.K. (National Council on Radiation Protection and Measurements, Bethesda, MD (USA))



Radiation-Induced Lymphocyte Apoptosis to Predict Radiation Therapy Late Toxicity in Prostate Cancer Patients  

SciTech Connect

Purpose: To examine a potential correlation between the in vitro apoptotic response of lymphocytes to radiation and the risk of developing late gastrointestinal (GI)/genitourinary (GU) toxicity from radiotherapy for prostate cancer. Methods and Materials: Prostate cancer patients formerly enrolled in a randomized study were tested for radiosensitivity by using a radiation-induced lymphocyte apoptosis assay. Apoptosis was measured using flow cytometry-based Annexin-FITC/7AAD and DiOC{sub 6}/7AAD assays in subpopulations of lymphocytes (total lymphocytes, CD4+, CD8+ and CD4-/CD8-) after exposure to an in vitro dose of 0, 2, 4, or 8 Gy. Results: Patients with late toxicity after radiotherapy showed lower lymphocyte apoptotic responses to 8 Gy than patients who had not developed late toxicity (p = 0.01). All patients with late toxicity had apoptosis levels that were at or below the group mean. The negative predictive value in both apoptosis assays ranged from 95% to 100%, with sensitivity values of 83% to 100%. Apoptosis at lower dose points and in lymphocyte subpopulations had a weaker correlation with the occurrence of late toxicity. Conclusions: Lymphocyte apoptosis after 8 Gy of radiation has the potential to predict which patients will be spared late toxicity after radiation therapy. Further research should be performed to identify the specific subset of lymphocytes that correlates with late toxicity, followed by a corresponding prospective study.

Schnarr, Kara [Department of Medicine, St. George's University, Grenada, WI (Grenada); Boreham, Douglas [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Sathya, Jinka [Department of Radiation Oncology, University of Manitoba, Winnipeg, MB (Canada); Julian, Jim [Department of Oncology, McMaster University, Hamilton, Ontario (Canada); Dayes, Ian S. [Department of Medical Physics and Applied Radiation Sciences, McMaster University, Hamilton, ON (Canada); Department of Oncology, McMaster University, Hamilton, Ontario (Canada)], E-mail:



Mechanisms of Radiation-Induced Bone Loss and Effect on Prostate Cancer Bone Metastases.  

National Technical Information Service (NTIS)

Patients with tumors in the pelvic region frequently receive radiation therapy, and as a result, bystander bone may experience adverse effects. Earlier reports demonstrated that radiation-induced bone loss occurs via increased osteoclast activation in a m...

H. S. Kim



Molecular mechanisms and treatment of radiation-induced lung fibrosis.  


Radiation-induced lung fibrosis (RILF) is a severe side effect of radiotherapy in lung cancer patients that presents as a progressive pulmonary injury combined with chronic inflammation and exaggerated organ repair. RILF is a major barrier to improving the cure rate and well-being of lung cancer patients because it limits the radiation dose that is required to effectively kill tumor cells and diminishes normal lung function. Although the exact mechanism is unclear, accumulating evidence suggests that various cells, cytokines and regulatory molecules are involved in the tissue reorganization and immune response modulation that occur in RILF. In this review, we will summarize the general symptoms, diagnostics, and current understanding of the cells and molecular factors that are linked to the signaling networks implicated in RILF. Potential approaches for the treatment of RILF will also be discussed. Elucidating the key molecular mediators that initiate and control the extent of RILF in response to therapeutic radiation may reveal additional targets for RILF treatment to significantly improve the efficacy of radiotherapy for lung cancer patients. PMID:23909719

Ding, Nian-Hua; Li, Jian Jian; Sun, Lun-Quan



Molecular Mechanisms and Treatment of Radiation-Induced Lung Fibrosis  

PubMed Central

Radiation-induced lung fibrosis (RILF) is a severe side effect of radiotherapy in lung cancer patients that presents as a progressive pulmonary injury combined with chronic inflammation and exaggerated organ repair. RILF is a major barrier to improving the cure rate and well-being of lung cancer patients because it limits the radiation dose that is required to effectively kill tumor cells and diminishes normal lung function. Although the exact mechanism is unclear, accumulating evidence suggests that various cells, cytokines and regulatory molecules are involved in the tissue reorganization and immune response modulation that occur in RILF. In this review, we will summarize the general symptoms, diagnostics, and current understanding of the cells and molecular factors that are linked to the signaling networks implicated in RILF. Potential approaches for the treatment of RILF will also be discussed. Elucidating the key molecular mediators that initiate and control the extent of RILF in response to therapeutic radiation may reveal additional targets for RILF treatment to significantly improve the efficacy of radiotherapy for lung cancer patients.

Ding, Nian-Hua; Li, Jian Jian; Sun, Lun-Quan



Radiation induced thyroid neoplasms 1920 to 1987: A vanishing problem  

SciTech Connect

Radiation for benign diseases has been implicated as an etiologic factor in thyroid cancer. From 1930-60, over 2 million children may have been exposed to therapeutic radiation and it is estimated that up to 7% may develop thyroid cancer after a 5-40 year latency. Thyroid stimulating hormone, secondary to radioinduced hypothyroidism, has been implicated as causative in animals. Such data has led to expensive screening programs in high risk patients. Because of a decline in irradiation for benign diseases in children over the last 2 decades, we questioned whether the incidence of radiation induced thyroid neoplasms (RITN) was also decreasing. Twenty-six of 227 patients (11%) with thyroid malignancies seen at our institution from 1974-87 had a history of previous head and neck irradiation. These included 13 papillary, 3 follicular, and 7 mixed carcinomas as well as 2 lymphomas and 1 synovial cell sarcoma. None of these 26 patients had abnormal thyroid function tests at presentation. Mean latency from irradiation to the diagnosis of thyroid cancer was 25.4 years (6-55 year range). Compared to the reported increasing incidence of RITN from 1940-70, there appears to be a significant decrease since 1970. Based on our analysis, the use of expensive screening programs in high risk populations may no longer be warranted. Additionally, the routine use of thyroid replacement in previously irradiated chemically hypothyroid patients is not recommended.30 references.

Mehta, M.P.; Goetowski, P.G.; Kinsella, T.J.



Involvement of prostaglandins and histamine in radiation-induced temperature responses in rats  

SciTech Connect

Exposure of rats to 1-15 Gy of gamma radiation induced hyperthermia, whereas exposure to 20-150 Gy produced hypothermia. Since radiation exposure induced the release of prostaglandins (PGs) and histamine, the role of PGs and histamine in radiation-induced temperature changes was examined. Radiation-induced hyper- and hypothermia were antagonized by pretreatment with indomethacin, a cyclooxygenase inhibitor. Intracerebroventricular administration of PGE2 and PGD2 induced hyper- and hypothermia, respectively. Administration of SC-19220, a specific PGE2 antagonist, attenuated PGE2- and radiation-induced hyperthermia, but it did not antagonize PGD2- or radiation-induced hypothermia. Consistent with an apparent role of histamine in hypothermia, administration of disodium cromoglycate (a mast cell stabilizer), mepyramine (H1-receptor antagonist), or cimetidine (H2-receptor antagonist) attenuated PGD2- and radiation-induced hypothermia. These results suggest that radiation-induced hyperthermia is mediated via PGE2 and that radiation-induced hypothermia is mediated by another PG, possibly PGD2, via histamine.

Kandasamy, S.B.; Hunt, W.A. (Armed Forces Radiobiology Research Institute, Bethesda, MD (USA))



Radiation-induced defects in clay minerals: A review  

NASA Astrophysics Data System (ADS)

Extensive information has been collected on radiation effects on clay minerals over the last 35 years, providing a wealth of information on environmental and geological processes. The fields of applications include the reconstruction of past radioelement migrations, the dating of clay minerals or the evolution of the physico-chemical properties under irradiation.The investigation of several clay minerals, namely kaolinite, dickite, montmorillonite, illite and sudoite, by Electron Paramagnetic Resonance Spectroscopy has shown the presence of defects produced by natural or artificial radiations. These defects consist mostly of electron holes located on oxygen atoms of the structure. The various radiation-induced defects are differentiated through their nature and their thermal stability. Most of them are associated with a ? orbital on a Si-O bond. The most abundant defect in clay minerals is oriented perpendicular to the silicate layer. Thermal annealing indicates this defect in kaolinite (A-center) to be stable over geological periods at ambient temperature. Besides, electron or heavy ion irradiation easily leads to an amorphization in smectites, depending on the type of interlayer cation. The amorphization dose exhibits a bell-shaped variation as a function of temperature, with a decreasing part that indicates the influence of thermal dehydroxylation. Two main applications of the knowledge of radiation-induced defects in clay minerals are derived: (i) The use of defects as tracers of past radioactivity. In geological systems where the age of the clay can be constrained, ancient migrations of radioelements can be reconstructed in natural analogues of high level nuclear waste repositories. When the dose rate may be assumed constant over time, the paleodose is used to date clay populations, an approach applied to fault gouges or laterites of the Amazon basin. (ii) The influence of irradiation over physico-chemical properties of clay minerals. An environmental application concerns the performance assessment of the engineered barrier of nuclear waste disposals. In case of a leakage of transuranic elements from the radioactive waste form, alpha recoil nuclei can amorphize smectite after periods of the order of 1000 years according to a worst case scenario, whereas amorphization from ionizing radiation is unlikely. As amorphization greatly enhances the dissolution kinetics of smectite, the sensitivity of the smectites must be taken into account in the prediction of the long term behavior of engineered barriers.

Allard, Th.; Balan, E.; Calas, G.; Fourdrin, C.; Morichon, E.; Sorieul, S.



Radiation-Induced Bystander Effects in Cultured Human Stem Cells  

PubMed Central

Background The radiation-induced “bystander effect” (RIBE) was shown to occur in a number of experimental systems both in vitro and in vivo as a result of exposure to ionizing radiation (IR). RIBE manifests itself by intercellular communication from irradiated cells to non-irradiated cells which may cause DNA damage and eventual death in these bystander cells. It is known that human stem cells (hSC) are ultimately involved in numerous crucial biological processes such as embryologic development; maintenance of normal homeostasis; aging; and aging-related pathologies such as cancerogenesis and other diseases. However, very little is known about radiation-induced bystander effect in hSC. To mechanistically interrogate RIBE responses and to gain novel insights into RIBE specifically in hSC compartment, both medium transfer and cell co-culture bystander protocols were employed. Methodology/Principal Findings Human bone-marrow mesenchymal stem cells (hMSC) and embryonic stem cells (hESC) were irradiated with doses 0.2 Gy, 2 Gy and 10 Gy of X-rays, allowed to recover either for 1 hr or 24 hr. Then conditioned medium was collected and transferred to non-irradiated hSC for time course studies. In addition, irradiated hMSC were labeled with a vital CMRA dye and co-cultured with non-irradiated bystander hMSC. The medium transfer data showed no evidence for RIBE either in hMSC and hESC by the criteria of induction of DNA damage and for apoptotic cell death compared to non-irradiated cells (p>0.05). A lack of robust RIBE was also demonstrated in hMSC co-cultured with irradiated cells (p>0.05). Conclusions/Significance These data indicate that hSC might not be susceptible to damaging effects of RIBE signaling compared to differentiated adult human somatic cells as shown previously. This finding could have profound implications in a field of radiation biology/oncology, in evaluating radiation risk of IR exposures, and for the safety and efficacy of hSC regenerative-based therapies.

Sokolov, Mykyta V.; Neumann, Ronald D.



Space-Radiation-Induced Photon Luminescence of the Moon  

NASA Astrophysics Data System (ADS)

We report on the results of a study of the photon luminescence of the Moon induced by Galactic Cosmic Rays (GCRs) and space radiation from the Sun, using the Monte Carlo program FLUKA. The model of the lunar surface is taken to be the chemical composition of soils found at various landing sites during the Apollo and Luna programs, averaged over all such sites to define a generic regolith for the present analysis. This then becomes the target that is bombarded by Galactic Cosmic Rays (GCRs) and Solar Energetic Particles (SEPs) above 1 keV in FLUKA to determine the photon fluence albedo produced by the Moon's surface when there is no sunlight and Earthshine. This is to be distinguished from the gamma-ray spectrum produced by the radioactive decay of radiogenic constituents lying in the surface and interior of the Moon. From the photon fluence we derive the spectrum which can be utilized to examine existing lunar spectral data and to design orbiting instrumentation for measuring various components of the space-radiation-induced photon luminescence present on the Moon.

Wilson, Thomas


Effect of radiation-induced amorphization on smectite dissolution.  


Effects of radiation-induced amorphization of smectite were investigated using artificial irradiation. Beams of 925 MeV Xenon ions with radiation dose reaching 73 MGy were used to simulate the effects generated by alpha recoil nuclei or fission products in the context of high level nuclear waste repository. Amorphization was controlled by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy. An important coalescence of the smectite sheets was observed which lead to a loss of interparticle porosity. The amorphization is revealed by a loss of long-range structure and accompanied by dehydroxylation. The dissolution rate far-from-equilibrium shows that the amount of silica in solution is two times larger in the amorphous sample than in the reference clay, a value which may be enhanced by orders of magnitude when considering the relative surface area of the samples. Irradiation-induced amorphization thus facilitates dissolution of the clay-derived material. This has to be taken into account for the safety assessment of high level nuclear waste repository, particularly in a scenario of leakage of the waste package which would deliver alpha emitters able to amorphize smectite after a limited period of time. PMID:20225848

Fourdrin, C; Allard, T; Monnet, I; Menguy, N; Benedetti, M; Calas, G



Image-based modeling of radiation-induced foci  

NASA Astrophysics Data System (ADS)

Several proteins involved in the response to DNA double strand breaks (DSB) form microscopically visible nuclear domains, or foci, after exposure to ionizing radiation. Radiation-induced foci (RIF) are believed to be located where DNA damage occurs. To test this assumption, we used Monte Carlo simulations to predict the spatial distribution of DSB in human nuclei exposed to high or low-LET radiation. We then compared these predictions to the distribution patterns of three DNA damage sensing proteins, i.e. 53BP1, phosphorylated ATM and ?H2AX in human mammary epithelial. The probability to induce DSB can be derived from DNA fragment data measured experimentally by pulsed-field gel electrophoresis. We first used this probability in Monte Carlo simulations to predict DSB locations in synthetic nuclei geometrically described by a complete set of human chromosomes, taking into account microscope optics from real experiments. Simulations showed a very good agreement for high-LET, predicting 0.7 foci/µm along the path of a 1 GeV/amu Fe particle against measurement of 0.69 to 0.82 foci/µm for various RIF 5 min following exposure (LET 150 keV/µm). On the other hand, discrepancies were shown in foci frequency for low-LET, with measurements 20One drawback using a theoretical model for the nucleus is that it assumes a simplistic and static pattern for DNA densities. However DNA damage pattern is highly correlated to DNA density pattern (i.e. the more DNA, the more likely to have a break). Therefore, we generalized our Monte Carlo approach to real microscope images, assuming pixel intensity of DAPI in the nucleus was directly proportional to the amount of DNA in that pixel. With such approach we could predict DNA damage pattern in real images on a per nucleus basis. Since energy is randomly deposited along high-LET particle paths, RIF along these paths should also be randomly distributed. As expected, simulations produced DNA-weighted random (Poisson) distributions. In contrast, the distributions of RIF obtained as early as 5 min after exposure to high LET (1 GeV/amu Fe) were non-random. This deviation from the expected DNA-weighted random pattern was further characterized by "relative DNA image measurements". This novel imaging approach showed that RIF were located preferentially at the interface between high and low DNA density regions, and were more frequent than predicted in regions with lower DNA density. The same preferential nuclear location was also measured for RIF induced by 1 Gy of low-LET radiation. This deviation from random behavior was evident only 5 min after irradiation for phosphorylated ATM RIF, while ?H2AX and 53BP1 RIF showed pronounced deviations up to 30 min after exposure. These data suggest that RIF within a few minutes following exposure to radiation cluster into open regions of the nucleus (i.e. euchromatin). It is possible that DNA lesions are collected in these nuclear sub-domains for more efficient repair. If so, this would imply that DSB are actively transported within the nucleus, a phenomenon that has not yet been considered in modeling DNA misrepair following exposure to radiation. These results are thus critical for more accurate risk models of radiation and we are actively working on characterizing further RIF movement in human nuclei using live cell imaging.

Costes, Sylvain; Cucinotta, Francis A.; Ponomarev, Artem; Barcellos-Hoff, Mary Helen; Chen, James; Chou, William; Gascard, Philippe


Motion-induced radiation from electrons moving in Maxwell's fish-eye.  


In ?erenkov radiation and transition radiation, evanescent wave from motion of charged particles transfers into radiation coherently. However, such dissipative motion-induced radiations require particles to move faster than light in medium or to encounter velocity transition to pump energy. Inspired by a method to detect cloak by observing radiation of a fast-moving electron bunch going through it by Zhang et al., we study the generation of electron-induced radiation from electrons' interaction with Maxwell's fish-eye sphere. Our calculation shows that the radiation is due to a combination of ?erenkov radiation and transition radiation, which may pave the way to investigate new schemes of transferring evanescent wave to radiation. PMID:24166002

Liu, Yangjie; Ang, L K



Motion-induced radiation from electrons moving in Maxwell's fish-eye  

PubMed Central

In ?erenkov radiation and transition radiation, evanescent wave from motion of charged particles transfers into radiation coherently. However, such dissipative motion-induced radiations require particles to move faster than light in medium or to encounter velocity transition to pump energy. Inspired by a method to detect cloak by observing radiation of a fast-moving electron bunch going through it by Zhang et al., we study the generation of electron-induced radiation from electrons' interaction with Maxwell's fish-eye sphere. Our calculation shows that the radiation is due to a combination of ?erenkov radiation and transition radiation, which may pave the way to investigate new schemes of transferring evanescent wave to radiation.

Liu, Yangjie; Ang, L. K.



A mechanistic model for radiation-induced crystallization and amorphization in U 3Si  

Microsoft Academic Search

Of concern for the proposed Advanced Neutron Source and Research Reactors, which would use intermetallic fuels, are potential radiation-induced phenomena that could affect the physical and mechanical properties of intermetallic aluminum dispersion fuels. For this reason and because of observations of radiation-induced amorphization of U3Si during ion irradiation, the phenomenology of radiation-induced amorphization is assessed. A rate theory model is

J. Rest



Radiation-induced versus endogenous DNA damage: possible effect of inducible protective responses in mitigating endogenous damage  

Microsoft Academic Search

Ionizing radiation (IR) causes damage to DNA that is apparently proportional to absorbed dose. The incidence of radiation-induced cancer in humans unequivocally rises with the value of absorbed doses above about 300 mGy, in a seemingly linear fashion. Extrapolation of this linear correlation down to zero-dose constitutes the linear-no-threshold (LNT) hypothesis of radiation-induced cancer incidence. The corresponding dose-risk correlation, however,

Myron Pollycove; Ludwig E Feinendegen



Fetal Radiation Exposure Induces Testicular Cancer in Genetically Susceptible Mice  

PubMed Central

The prevalence of testicular germ cell tumors (TGCT), a common solid tissue malignancy in young men, has been annually increasing at an alarming rate of 3%. Since the majority of testicular cancers are derived from germ cells at the stage of transformation of primordial germ cell (PGC) into gonocytes, the increase has been attributed to maternal/fetal exposures to environmental factors. We examined the effects of an estrogen (diethylstilbestrol, DES), an antiandrogen (flutamide), or radiation on the incidence of testicular germ cell tumors in genetically predisposed 129.MOLF-L1 (L1) congenic mice by exposing them to these agents on days 10.5 and 11.5 of pregnancy. Neither flutamide nor DES produced noticeable increases in testis cancer incidence at 4 weeks of age. In contrast, two doses of 0.8-Gy radiation increased the incidence of TGCT from 45% to 100% in the offspring. The percentage of mice with bilateral tumors, weights of testes with TGCT, and the percentage of tumors that were clearly teratomas were higher in the irradiated mice than in controls, indicating that irradiation induced more aggressive tumors and/or more foci of initiation sites in each testis. This radiation dose did not disrupt spermatogenesis, which was qualitatively normal in tumor-free testes although they were reduced in size. This is the first proof of induction of testicular cancer by an environmental agent and suggests that the male fetus of women exposed to radiation at about 5–6 weeks of pregnancy might have an increased risk of developing testicular cancer. Furthermore, it provides a novel tool for studying the molecular and cellular events of testicular cancer pathogenesis.

Shetty, Gunapala; Comish, Paul B.; Weng, Connie C. Y.; Matin, Angabin; Meistrich, Marvin L.



Fetal radiation exposure induces testicular cancer in genetically susceptible mice.  


The prevalence of testicular germ cell tumors (TGCT), a common solid tissue malignancy in young men, has been annually increasing at an alarming rate of 3%. Since the majority of testicular cancers are derived from germ cells at the stage of transformation of primordial germ cell (PGC) into gonocytes, the increase has been attributed to maternal/fetal exposures to environmental factors. We examined the effects of an estrogen (diethylstilbestrol, DES), an antiandrogen (flutamide), or radiation on the incidence of testicular germ cell tumors in genetically predisposed 129.MOLF-L1 (L1) congenic mice by exposing them to these agents on days 10.5 and 11.5 of pregnancy. Neither flutamide nor DES produced noticeable increases in testis cancer incidence at 4 weeks of age. In contrast, two doses of 0.8-Gy radiation increased the incidence of TGCT from 45% to 100% in the offspring. The percentage of mice with bilateral tumors, weights of testes with TGCT, and the percentage of tumors that were clearly teratomas were higher in the irradiated mice than in controls, indicating that irradiation induced more aggressive tumors and/or more foci of initiation sites in each testis. This radiation dose did not disrupt spermatogenesis, which was qualitatively normal in tumor-free testes although they were reduced in size. This is the first proof of induction of testicular cancer by an environmental agent and suggests that the male fetus of women exposed to radiation at about 5-6 weeks of pregnancy might have an increased risk of developing testicular cancer. Furthermore, it provides a novel tool for studying the molecular and cellular events of testicular cancer pathogenesis. PMID:22348147

Shetty, Gunapala; Comish, Paul B; Weng, Connie C Y; Matin, Angabin; Meistrich, Marvin L



Strain-induced macroscopic magnetic anisotropy from smectic liquid-crystalline elastomer-maghemite nanoparticle hybrid nanocomposites  

NASA Astrophysics Data System (ADS)

We combine tensile strength analysis and X-ray scattering experiments to establish a detailed understanding of the microstructural coupling between liquid-crystalline elastomer (LCE) networks and embedded magnetic core-shell ellipsoidal nanoparticles (NPs). We study the structural and magnetic re-organization at different deformations and NP loadings, and the associated shape and magnetic memory features. In the quantitative analysis of a stretching process, the effect of the incorporated NPs on the smectic LCE is found to be prominent during the reorientation of the smectic domains and the softening of the nanocomposite. Under deformation, the soft response of the nanocomposite material allows the organization of the nanoparticles to yield a permanent macroscopically anisotropic magnetic material. Independent of the particle loading, the shape-memory properties and the smectic phase of the LCEs are preserved. Detailed studies on the magnetic properties demonstrate that the collective ensemble of individual particles is responsible for the macroscopic magnetic features of the nanocomposite.We combine tensile strength analysis and X-ray scattering experiments to establish a detailed understanding of the microstructural coupling between liquid-crystalline elastomer (LCE) networks and embedded magnetic core-shell ellipsoidal nanoparticles (NPs). We study the structural and magnetic re-organization at different deformations and NP loadings, and the associated shape and magnetic memory features. In the quantitative analysis of a stretching process, the effect of the incorporated NPs on the smectic LCE is found to be prominent during the reorientation of the smectic domains and the softening of the nanocomposite. Under deformation, the soft response of the nanocomposite material allows the organization of the nanoparticles to yield a permanent macroscopically anisotropic magnetic material. Independent of the particle loading, the shape-memory properties and the smectic phase of the LCEs are preserved. Detailed studies on the magnetic properties demonstrate that the collective ensemble of individual particles is responsible for the macroscopic magnetic features of the nanocomposite. Electronic supplementary information (ESI) available: Fig. ESI-1: polarized optical microscopy images, Fig. ESI-2-4: supplementary X-ray data, Fig. ESI-5: FORC diagrams. See DOI: 10.1039/c3nr01016c

Haberl, Johannes M.; Sánchez-Ferrer, Antoni; Mihut, Adriana M.; Dietsch, Hervé; Hirt, Ann M.; Mezzenga, Raffaele



Radiation-induced attenuation of high-OH optical fibers after hydrogen treatment in the presence of ionizing radiation  

SciTech Connect

High purity, high-OH, optical fibers were irradiated in a hydrogen atmosphere to explore hydrogen binding into defects created by the ionizing radiation. Significant improvements in subsequent measurements of radiation-induced attenuation were observed. 18 refs., 4 figs., 2 tabs.

Lyons, P.B; Looney, L.D.



Role of Neurotensin in Radiation-Induced Hypothermia in Rats. (Reannouncement with New Availability Information).  

National Technical Information Service (NTIS)

The role of neurotensin in radiation induced hypothermia was examined. Intracerebroventricular (ICV) administration of neurotensin produced dose-dependent hypothermia. Histamine appears to mediate neurotensin-induced hypothermia because the mast cell stab...

S. B. Kandasamy W. A. Hunt A. H. Harris



Radiation-induced gas evolution from commercial lubricant base oil  

SciTech Connect

Radiation-induced evolved gases for 20 commercial lubricant base oils were measured at room temperature. Samples were irradiated under vacuum by /sup 60/Co gamma rays at a dose rate of 1 Mrad/h up to 1000 Mrad for mineral oils and ester lubricants, and 3000 Mrad for aromatic lubricants. The evolved gas was measured by means of gas chromatography. The G values (number of gas molecules liberated per absorbed energy of 100 eV) of total evolved gases are 2.8 for liquid paraffins, 1.4 for paraffinic neutral oils, 1.5 to 1.9 for esters, 0.26 to 0.56 for alkyl diphenyl ethers, and 0.005 for phenoxy-phenoxydiphenyl.

Kazuo, A.; Nashiro, H.



Radiation-induced polymerization for the immobilization of penicillin acylase  

SciTech Connect

The immobilization of Escherichia coli penicillin acylase was investigated by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperature. A leak-proof composite that does not swell in water was obtained by adding the cross-linking agent trimethylolpropane trimethacrylate to the monomer-aqueous enzyme mixture. Penicillin acylase, which was immobilized with greater than 70% yield, possessed a higher Km value toward the substrate 6-nitro-3-phenylacetamidobenzoic acid than the free enzyme form (Km = 1.7 X 10(-5) and 1 X 10(-5) M, respectively). The structural stability of immobilized penicillin acylase, as assessed by heat, guanidinium chloride, and pH denaturation profiles, was very similar to that of the free-enzyme form, thus suggesting that penicillin acylase was entrapped in its native state into aqueous free spaces of the polymer matrix.

Boccu, E.; Carenza, M.; Lora, S.; Palma, G.; Veronese, F.M.



Radiation-induced chromosomal instability in human mammary epithelial cells  

NASA Astrophysics Data System (ADS)

Karyotypes of human cells surviving X- and alpha-irradiation have been studied. Human mammary epithelial cells of the immortal, non-tumorigenic cell line H184B5 F5-1 M/10 were irradiated and surviving clones isolated and expanded in culture. Cytogenetic analysis was performed using dedicated software with an image analyzer. We have found that both high- and low-LET radiation induced chromosomal instability in long-term cultures, but with different characteristics. Complex chromosomal rearrangements were observed after X-rays, while chromosome loss predominated after alpha-particles. Deletions were observed in both cases. In clones derived from cells exposed to alpha-particles, some cells showed extensive chromosome breaking and double minutes. Genomic instability was correlated to delayed reproductive death and neoplastic transformation. These results indicate that chromosomal instability is a radiation-quality-dependent effect which could determine late genetic effects, and should therefore be carefully considered in the evaluation of risk for space missions.

Durante, M.; Grossi, G. F.; Yang, T. C.


Radiation-induced sarcomas of the chest wall  

SciTech Connect

Sixteen patients are presented who had sarcomas of the chest wall at a site where a prior malignancy had been irradiated. The first malignancies included breast cancer (ten cases), Hodgkin's disease (four cases), and others (two cases). Radiation doses varied from 4200 to 5500 R (mean, 4900 R). The latency period ranged from 5 to 28 years (mean, 13 years). The histologic types of the radiation-induced sarcomas were as follows: malignant fibrous histiocytoma, nine cases; osteosarcoma, six cases; and malignant mesenchymoma, one case. The only long-term survivor is alive and well 12 years after resection of a clavicular chondroblastic osteosarcoma. Three cases were recently diagnosed. Despite aggressive multimodality treatment, the remaining 13 patients have all died from their sarcomas (mean survival, 13.5 months). All patients have apparently been cured of their first malignancies. Chemotherapy was ineffective. No treatment, including forequarter amputation, appeared to palliate the patients with supraclavicular soft tissue sarcomas. Major chest wall resection offered good palliation for seven of eight patients with sarcomas arising in the sternum or lateral chest wall. Close follow-up is needed to detect signs of these sarcomas in the ever-increasing number of patients receiving therapeutic irradiation.

Souba, W.W.; McKenna, R.J. Jr.; Meis, J.; Benjamin, R.; Raymond, A.K.; Mountain, C.F.



Are Epigenetic Mechanisms Involved in Radiation-Induced Bystander Effects?  

PubMed Central

The “non-targeted effects” of ionizing radiation including bystander effects and genomic instability are unique in that no classic mutagenic event occurs in the cell showing the effect. In the case of bystander effects, cells which were not in the field affected by the radiation show high levels of mutations, chromosome aberrations, and membrane signaling changes leading to what is termed “horizontal transmission” of mutations and information which may be damaging while in the case of genomic instability, generations of cells derived from an irradiated progenitor appear normal but then lethal and non-lethal mutations appear in distant progeny. This is known as “vertical transmission.” In both situations high yields of non-clonal mutations leading to distant occurrence of mutation events both in space and time. This precludes a mutator phenotype or other conventional explanation and appears to indicate a generalized form of stress-induced mutagenesis which is well documented in bacteria. This review will discuss the phenomenology of what we term “non-targeted effects,” and will consider to what extent they challenge conventional ideas in genetics and epigenetics.

Mothersill, Carmel; Seymour, Colin



Radiation-induced tumors in transplanted ovaries. [Mice  

SciTech Connect

A comparison was made of tumor induction in the ovaries of whole-body-irradiation mice (250-kV X rays, doses of 0.25-4.00 Gy) or in ovaries irradiated in vivo and then transplanted intramuscularly into castrated syngeneic hosts. The form of the dose-induction relationships was similar in the two cases, showing a steeply rising branch at doses up to 0.75 Gy followed by a maximum and an elevated plateau up to 4.00 Gy. A higher incidence of tumors in transplanted organs was apparent for doses up to the maximum, which was attributed to castration-induced hormonal imbalance. Specific death rate analysis of mice dying with ovarian tumors showed that in this system radiation acts essentially by decreasing tumor latency. Ovarian tumors were classified in various histological types and their development in time was followed by serial sacrifice. Separate analysis of death rate of animals carrying different tumor classes allowed further resolution of the various components of the tumor induction phenomenon. It was thus possible to show that the overall death rate analysis masks a true effect of induction of granulosa cell tumors in whole-body-irradiation animals. The transplantation technique offers little advantage for the study of radiation induction of ovarian tumor.

Covelli, V.; Di Majo, V.; Bassani, B.; Metalli, P.; Silini, G.



Radiation-induced leukemia: Comparative studies in mouse and man  

SciTech Connect

We now have a clear understanding of the mechanism by which radiation-induced (T-cell) leukemia occurs. In irradiated mice (radiation-induced thymic leukemia) and in man (acute lymphoblastic T-cell leukemia, T-ALL) the mechanism of leukemogenesis is surprisingly similar. Expressed in the most elementary terms, T-cell leukemia occurs when T-cell differentiation is inhibited by a mutation, and pre-T cells attempt but fail to differentiate in the thymus. Instead of leaving the thymus for the periphery as functional T-cells they continue to proliferate in the thymus. The proliferating pre- (pro-) T-cells constitute the (early) acute T-cell leukemia (A-TCL). This model for the mechanism of T-cell leukemogenesis accounts for all the properties of both murine and human A-TCL. Important support for the model has recently come from work by Ilan Kirsch and others, who have shown that mutations/deletions in the genes SCL (TAL), SIL, and LCK constitute primary events in the development of T-ALL, by inhibiting differentiation of thymic pre- (pro-) T-cells. This mechanism of T-cell leukemogenesis brings several specific questions into focus: How do early A-TCL cells progress to become potently tumorigenic and poorly treatable Is it feasible to genetically suppress early and/or progressed A-TCL cells What is the mechanism by which the differentiation-inhibited (leukemic) pre-T cells proliferate During the first grant year we have worked on aspects of all three questions.

Haas, M.



Coupled effects of director orientations and boundary conditions on light induced bending of monodomain nematic liquid crystalline polymer plates  

NASA Astrophysics Data System (ADS)

A photo-chromic liquid crystal polymers (LCPs) is a smart material for large light-activated variation or bending to transfer luminous energy into mechanical energy. We study the light induced behavior by modeling planar and homeotropic nematic network polymer plates. We effectively illustrate some reported experimental outcomes and theoretically predict some possible bending patterns. This paper constructs an understanding between the bending behaviors and interactions among the alignments, aspect ratios and boundary conditions, etc. Our work provides information on optimizing light induced bending in the process of micro-opto-mechanical system (MOMS) design.

You, Yue; Xu, Changwei; Ding, Shurong; Huo, Yongzhong



Pressure-induced lattice collapse in the tetragonal phase of single-crystalline Fe(1.05)Te  

SciTech Connect

Pressure-induced lattice collapse was discovered in tetragonal T phase of single crystal Fe{sub 1.05}Te at room temperature through x-ray and neutron-diffraction measurements. A remarkable compression along the c axis {approx}5% was observed upon increasing pressure from the ambient condition to 4 GPa. Indexed results demonstrate that the crystallographic structure remains unchanged after the collapse, revealing that the collapse does not break symmetry of crystal structure. The Fe-spin state change was proposed to account for the lattice collapse. The equations of state for the T phase and pressure-induced collapsed T phase were determined from the diffraction measurements.

Zhang, Chao [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Yi, Wei [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Sun, Liling [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Chen, Xiao-Jia [Carnegie Institution of Washington; Hemley, Russell [Carnegie Institution of Washington; Mao, Ho-Kwang [Carnegie Institution of Washington; Lu, Wei [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Dong, Xiaoli [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Ligang, Bai [Institute of High Energy Physics, Chinese Academy of Sciences, China; Jing, Liu [Institute of High Energy Physics, Chinese Academy of Sciences, China; Moreira Dos Santos, Antonio F [ORNL; Molaison, Jamie J [ORNL; Tulk, Christopher A [ORNL; Chen, Genfu [Beijing National Laboratory for Condensed Matter Physics/Chinese Academy of Scie; Wang, Nanlin [The Institute of Physics, Chinese Academy of Sciences; Zhao, Zhongxian [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics



Radiation-induced osteosarcomas in the pediatric population  

SciTech Connect

Purpose: Radiation-induced osteosarcomas (R-OS) have historically been high-grade, locally invasive tumors with a poor prognosis. The purpose of this study was to perform a comprehensive literature review and analysis of reported cases dealing with R-OS in the pediatric population to identify the characteristics, prognostic factors, optimal treatment modalities, and overall survival of these patients. Methods and Materials: A MEDLINE/PubMed search of articles written in the English language dealing with OSs occurring after radiotherapy (RT) in the pediatric population yielded 30 studies from 1981 to 2004. Eligibility criteria included patients <21 years of age at the diagnosis of the primary cancer, cases satisfying the modified Cahan criteria, and information on treatment outcome. Factors analyzed included the type of primary cancer treated with RT, the radiation dose and beam energy, the latency period between RT and the development of R-OS, and the treatment, follow-up, and final outcome of R-OS. Results: The series included 109 patients with a median age at the diagnosis of primary cancer of 6 years (range, 0.08-21 years). The most common tumors treated with RT were Ewing's sarcoma (23.9%), rhabdomyosarcoma (17.4%), retinoblastoma (12.8%), Hodgkin's disease (9.2%), brain tumor (8.3%), and Wilms' tumor (6.4%). The median radiation dose was 47 Gy (range, 15-145 Gy). The median latency period from RT to the development of R-OS was 100 months (range, 36-636 months). The median follow-up after diagnosis of R-OS was 18 months (1-172 months). The 3- and 5-year cause-specific survival rate was 43.6% and 42.2%, respectively, and the 3- and 5-year overall survival rate was 41.7% and 40.2%, respectively. Variables, including age at RT, primary site, type of tumor treated with RT, total radiation dose, and latency period did not have a significant effect on survival. The 5-year cause-specific and overall survival rate for patients who received treatment for R-OS involving chemotherapy alone, surgery alone, and surgery plus chemotherapy was 17.3% and 17.3%, 56.6% and 50.3%, and 71.0% and 68.3%, respectively (p < 0.0001, log-rank test). Conclusion: The type of treatment for R-OS was the most significant factor for cause-specific and overall survival. Patients who develop R-OS should be aggressively treated, because the outcome is not as dismal as once thought.

Koshy, Matthew [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States); Paulino, Arnold C. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States)]. E-mail:; Mai, Wei Y. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States); Teh, Bin S. [Department of Radiology, Division of Radiation Oncology, Baylor College of Medicine, Methodist Hospital, and Texas Children's Hospital, Houston, TX (United States)



A bulk current injection test conforming to statistical properties of radiation-induced effects  

Microsoft Academic Search

In this paper, a bulk current injection (BCI) immunity test is designed that conforms to the effects induced in the equipment under test (EUT) by a radiated electromagnetic disturbance (EMD). This is done by adopting a statistical description of the EMD and by comparing currents induced by BCI and distributed field-coupling (i.e., radiation) in the input pins of the EUT.

Giordano Spadacini; Sergio A. Pignari



Attenuation of a Radiation-Induced Conditioned Taste Aversion after the Development of Ethanol Tolerance,  

National Technical Information Service (NTIS)

An attempt to reduce a radiation-induced conditioned taste aversion (CTA) was undertaken by rendering animals tolerant to ethanol. Ethanol tolerance, developed over 5 days, was sufficient to block a radiation-induced taste aversion, as well as an ethanol-...

B. M. Rabin W. A. Hunt




EPA Science Inventory

A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposures...



EPA Science Inventory

A rapid and sensitive fluorescence assay for radiation-induced DNA damage is reported. Changes in temperature-induced strand separation in both calf thymus DNA and plasmid DNA (puc 19 plasmid from Escherichia coli) were measured after exposure to low doses of radiation. Exposur...


Universal damage factor for radiation-induced dark current in silicon devices  

Microsoft Academic Search

A new damage factor formulation is presented for describing radiation-induced dark current in silicon devices. This damage factor, K dark, is the number of carriers thermally generated per unit volume per unit time in a depletion region per unit nonionizing dose deposited in that volume. Kdark appears to account successfully for the mean radiation-induced dark current for any silicon device

J. R. Srour; D. H. Lo



Antioxidant properties of Asparagus racemosus against damage induced by ?-radiation in rat liver mitochondria  

Microsoft Academic Search

The possible antioxidant effects of crude extract and a purified aqueous fraction of Asparagus racemosus against membrane damage induced by the free radicals generated during ?-radiation were examined in rat liver mitochondria. ?-Radiation, in the dose range of 75–900 Gy, induced lipid peroxidation as assessed by the formation of thiobarbituric acid reactive substances (TBARS) and lipid hydroperoxides (LOOH). Using an

Jayashree P Kamat; Krutin K Boloor; Thomas P. A Devasagayam; S. R Venkatachalam



Deep Level Transient Spectroscopy Technique to Analyze Radiation Induced Defects in Power Transistors  

SciTech Connect

Deep Level Transient Spectroscopy (DLTS) technique is useful tool to study process and radiation induced defects in semiconductor materials and devices. The different types of radiation induced trap levels in the collector-base depletion region of the transistors were studied by DLTS technique.

Prakash, A. P. Gnana [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore, Karnataka-570006 (India)



Radioprotective effect of geraniin via the inhibition of apoptosis triggered by ?-radiation-induced oxidative stress.  


The radioprotective effect of geraniin, a tannin compound isolated from Nymphaea tetragona Georgi var. (Nymphaeaceae), against ?-radiation-induced damage was investigated in Chinese hamster lung fibroblast (V79-4) cells. Geraniin recovered cell viability detected by MTT test and colony formation assay, which was compromised by ?-radiation, and reduced the ?-radiation-induced apoptosis by the inhibition of loss of the mitochondrial membrane potential. Geraniin protected cellular components (lipid membrane, cellular protein, and DNA) damaged by ?-radiation, which was detected by lipid peroxidation, protein carbonyl formation, and comet assay. Geraniin significantly reduced the level of intracellular reactive oxygen species generated by ?-radiation, which was detected using spectrofluorometer, flow cytometer, and confocal microscope after 2',7'-dichlorodihydrofluorescein diacetate staining. Geraniin normalized the superoxide dismutase and catalase activities, which were decreased by ?-radiation. These results suggest that geraniin protects cells against radiation-induced oxidative stress via enhancing of antioxidant enzyme activities and attenuating of cellular damage. PMID:20680428

Kang, Kyoung Ah; Lee, In Kyung; Zhang, Rui; Piao, Mei Jing; Kim, Ki Cheon; Kim, Sang Young; Shin, Taekyun; Kim, Bum Joon; Lee, Nam Ho; Hyun, Jin Won



Mitochondrial ROS and radiation induced transformation in mouse embryonic fibroblasts.  


Manganese superoxide dismutase (SOD2) is a nuclear encoded and mitochondria localized antioxidant enzyme that converts mitochondria derived superoxide to hydrogen peroxide. This study investigates the hypothesis that mitochondria derived reactive oxygen species (ROS) regulate ionizing radiation (IR) induced transformation in normal cells. Mouse embryonic fibroblasts (MEFs) with wild type SOD2 (+/+), heterozygous SOD2 (+/-), and homozygous SOD2 (-/-) genotypes were irradiated with equitoxic doses of IR, and assayed for transformation frequency, cellular redox environment, DNA damage, and cell cycle checkpoint activation. Transformation frequency increased ( approximately 5-fold) in SOD2 (-/-) compared to SOD2 (+/+) MEFs. Cellular redox environment (GSH, GSSG, DHE and DCFH-oxidation) did not show any significant change within 24 h post-IR. However, a significant increase in cellular ROS levels was observed at 72 h post-IR in SOD2 (-/-) compared to SOD2 (+/+) MEFs, which was consistent with an increase in GSSG in SOD2 (-/-) MEFs. Late ROS accumulation was associated with an increase in micronuclei frequency in SOD2 (-/-) MEFs. Exit from G(2) was accelerated in irradiated SOD2 (+/-) and SOD2 (-/-) compared to SOD2 (+/+) MEFs. These results support the hypothesis that SOD2 activity and mitochondria generated ROS regulate IR induced transformation in mouse embryonic fibroblasts. PMID:19738419

Du, Changbin; Gao, Zhen; Venkatesha, Venkatasubbaiah A; Kalen, Amanda L; Chaudhuri, Leena; Spitz, Douglas R; Cullen, Joseph J; Oberley, Larry W; Goswami, Prabhat C



Carcinomatous versus radiation-induced brachial plexus neuropathy in breast cancer  

Microsoft Academic Search

A retrospective study was performed of 18 women in whom ipsilateral brachial plexus neuropathy developed after treatment for carcinoma of the breast. In the absence of metastatic tumor elsewhere, the only distinguishing feature between carcinomatous neuropathy and radiation-induced neuropathy was the symptom-free interval after mastectomy and radiation therapy. Women with an interval of less than a year have radiation-induced neuropathy.

Frederick H. Bagley; John W. Walsh; Blake Cady; Ferdinand A. Salzman; Richard A. Oberfield; Artemis G. Pazianos



Molecular dynamics simulations of temperature- and pressure-induced solid–solid phase transitions in crystalline para-terphenyl  

Microsoft Academic Search

Molecular dynamics (MD) simulations of pressure- and temperature-induced solid–solid phase transitions in para-terphenyl have been investigated using Material Studio. Initial simulations were performed using the COMPASS (condensed-phase optimised molecular potentials for atomistic simulation studies) force field to evaluate its ability to model the known temperature and pressure phase boundary between the triclinic and monoclinic crystal phases. Geometry optimisation using the

Bohdan Schatschneider; Eric L. Chronister



p53 status in radiation-induced soft-tissue sarcomas  

Microsoft Academic Search

Background  Following therapeutic irradiation after a latency period of many years radiation-induced tumors, often sarcomas, can arise.\\u000a Results of radiation-induced DNA damage can be 1. p53 over-expression, inducing growth arrest or apoptosis, and 2. occurrence\\u000a of mutations, frequently including the p53 gene, as one molecular promotor for carcinogenesis. We were interested whether\\u000a radiation-induced sarcomas are associated with alterations of the p53

Helge Taubert; Axel Meye; Matthias Bache; Raoul Hinze; Hans-Jtirgen Holzhausen; Hannelore Schmidt; Friedrich-Wilhelm Rath; Jürgen Dunst; Peter Würl



Harmonic tracking of acoustic radiation force-induced displacements.  


Ultrasound-based elasticity imaging methods rely upon accurate estimates of tissue deformation to characterize the mechanical properties of soft tissues. These methods are corrupted by clutter, which can bias and/or increase variance in displacement estimates. Harmonic imaging methods are routinely used for clutter suppression and improved image quality in conventional B-mode ultrasound, but have not been utilized in ultrasound-based elasticity imaging methods. We introduce a novel, fully-sampled pulse-inversion harmonic method for tracking tissue displacements that corrects the loss in temporal sampling frequency associated with conventional pulse-inversion techniques. The method is implemented with acoustic radiation force impulse (ARFI) imaging to monitor the displacements induced by an impulsive acoustic radiation force excitation. Custom pulse sequences were implemented on a diagnostic ultrasound scanner to collect spatially-matched fundamental and harmonic information within a single acquisition. B-mode and ARFI images created from fundamental data collected at 4 MHz and 8 MHz are compared with 8-MHz harmonic images created using a band-pass filter approach and the fully sampled pulse-inversion method. In homogeneous, tissue-mimicking phantoms, where no visible clutter was observed, there was little difference in the axial displacements, estimated jitter, and normalized cross-correlation among the fundamental and harmonic tracking methods. The similarity of the lower- and higher-frequency methods suggests that any improvement resulting from the increased frequency of the harmonic components is negligible. The harmonic tracking methods demonstrated a marked improvement in B-mode and ARFI image quality of in vivo carotid arteries. Improved feature detection and decreased variance in estimated displacements were observed in the arterial walls of harmonic ARFI images, especially in the pulse-inversion harmonic ARFI images. Within the lumen, the harmonic tracking m. PMID:24158290



Response of advanced bipolar processes to ionizing radiation  

Microsoft Academic Search

Ionizing radiation induced gain degradation in microcircuit bipolar polysilicon and crystalline emitter transistors is investigated. In this work, 60Co irradiation testing was performed on bipolar test structures. The effects of collector bias, dose rate, and anneal temperature are discussed. Major differences in the radiation response of polysilicon emitter transistors are demonstrated as a function of dose rate. The worst-case gain

Edward W. Enlow; Ronald L. Pease; William Combs; Ron D. Schrimpf; R. Nathan Nowlin



Radiation-Induced Topological Disorder in Irradiated Network Structures  

SciTech Connect

This report summarizes results of a research program investigating the fundamental principles underlying the phenomenon of topological disordering in a radiation environment. This phenomenon is known popularly as amorphization, but is more formally described as a process of radiation-induced structural arrangement that leads in crystals to loss of long-range translational and orientational correlations and in glasses to analogous alteration of connectivity topologies. The program focus has been on a set compound ceramic solids with directed bonding exhibiting structures that can be described as networks. Such solids include SiO2, Si3N4, SiC, which are of interest to applications in fusion energy production, nuclear waste storage, and device manufacture involving ion implantation or use in radiation fields. The principal investigative tools comprise a combination of experimental diffraction-based techniques, topological modeling, and molecular-dynamics simulations that have proven a rich source of information in the preceding support period. The results from the present support period fall into three task areas. The first comprises enumeration of the rigidity constraints applying to (1) more complex ceramic structures (such as rutile, corundum, spinel and olivine structures) that exhibit multiply polytopic coordination units or multiple modes of connecting such units, (2) elemental solids (such as graphite, silicon and diamond) for which a correct choice of polytope is necessary to achieve correct representation of the constraints, and (3) compounds (such as spinel and silicon carbide) that exhibit chemical disorder on one or several sublattices. With correct identification of the topological constraints, a unique correlation is shown to exist between constraint and amorphizability which demonstrates that amorphization occurs at a critical constraint loss. The second task involves the application of molecular dynamics (MD) methods to topologically-generated models of amorphized network silicas. These methods are shown to generate fully connected topologically-disordered networks, equilibrated to achieve accurately-specified atomic coordinates that can be compared to correlation data derived from diffraction experiments. The MD equilibrations demonstrate the insensitivity of diffraction methods to substantial differences in intermediate-range topology, with the exception of the first diffraction peak which is shown to be uniquely sensitive to topological differences. The third task concerns application of MD simulations to amorphization of silicon carbide, which exhibits anomalous amorphizability. Amorphization of this compound is shown to derive from its facility for tolerating chemical disorder, and a critical homonuclear bond density threshold is established as a criterion for its amorphization.

Hobbs, Linn W.



Amorphous to crystalline phase transition in carbon induced by intense femtosecond x-ray free-electron laser pulses  

NASA Astrophysics Data System (ADS)

We present the results of an experiment where amorphous carbon undergoes a phase transition induced by femtosecond 830 eV x-ray free-electron laser pulses. The phase transition threshold fluence is found to be 282 ± 11 mJ/cm2. Atomic force microscopy, photoelectron microscopy, and micro-Raman spectroscopy give experimental evidence for the phase transition in terms of a volume expansion, graphitization, and change of local order of the irradiated sample area. The interaction is modeled by an accurate time-dependent treatment of the ionization dynamics coupled to a two-temperature model. At the phase transition fluence threshold the free-electron density Ne is found to be at maximum 9 × 1020 cm-3 while the ion (atom) temperature is found to be 1050 K, e.g., above the crystallization activation temperature reported in the literature. This low ionization rate and high atom temperature suggest a thermally activated phase transition.

Gaudin, J.; Peyrusse, O.; Chalupský, J.; Toufarová, M.; Vyšín, L.; Hájková, V.; Sobierajski, R.; Burian, T.; Dastjani-Farahani, Sh.; Graf, A.; Amati, M.; Gregoratti, L.; Hau-Riege, S. P.; Hoffmann, G.; Juha, L.; Krzywinski, J.; London, R. A.; Moeller, S.; Sinn, H.; Schorb, S.; Störmer, M.; Tschentscher, Th.; Vorlí?ek, V.; Vu, H.; Bozek, J.; Bostedt, C.



Large-grain poly-crystalline silicon thin films prepared by aluminum-induced crystallization of sputter-deposited hydrogenated amorphous silicon  

SciTech Connect

A metal-induced crystallization (MIC) technique was used to produce large-grain poly-crystalline silicon. Two sets of samples were prepared by first sputtering Al onto glass substrates. For one set of samples, hydrogenated amorphous silicon (a-Si:H) was sputtered on top of the Al without breaking the vacuum. For the second set, the samples were taken out of the vacuum chamber and exposed to the atmosphere to grow a very thin layer of native aluminum oxide before sputter depositing the a-Si:H. Both sets of samples were then annealed at temperatures between 400 and 525C for 40 min. X-ray diffraction patterns confirmed the crystallization of the samples. Scanning Auger microanalysis was used to confirm that the a-Si:H and Al layers exchanged positions in this structure during the crystallization process. Auger mapping revealed the formation of large grain poly-silicon (10-20 m). A model is proposed to explain how the crystallization process progresses with anneal temperature.

Hossain, Maruf [University of Arkansas; Meyer III, Harry M [ORNL; Abu-Safe, Husam H [University of Arkansas; Naseem, Hameed [University of Arkansas; Brown, Walter D [University of Arkansas




Microsoft Academic Search

PurposeRadiation therapy has been used successfully to treat pelvic malignancy but morbidity from hemorrhagic cystitis remains a major long-term sequela in 1 to 2% of patients. Obliterative endarteritis secondary to ionizing radiation leads to tissue hypoxia and poor healing. Hyperbaric oxygen therapy has been demonstrated to improve angiogenesis and promote healing in radiation injured tissue, including the bladder. We describe




INTERACTION OF LASER RADIATION WITH MATTER: Resonance laser-induced ionisation of sodium vapour taking radiative transfer into account  

NASA Astrophysics Data System (ADS)

The problem of ionisation of atomic sodium in the field of resonance laser radiation is numerically solved taking radiative transfer into account. Seed electrons are produced due to the mechanism of associative ionisation, then they gain energy in superelastic processes (collisions of the second kind) and initiate the avalanche ionisation of the medium by electron impact. We studied the effect of secondary radiation on the laser pulse propagation upon competition between the ionising and quenching electron collisions with excited atoms, on the kinetics of ionisation-induced vapour bleaching, and the plasma channel expansion in the form of a halo.

Kosarev, N. I.; Shaparev, N. Ya



Ionizing radiation induces heritable disruption of epithelial cell interactions  

PubMed Central

Ionizing radiation (IR) is a known human breast carcinogen. Although the mutagenic capacity of IR is widely acknowledged as the basis for its action as a carcinogen, we and others have shown that IR can also induce growth factors and extracellular matrix remodeling. As a consequence, we have proposed that an additional factor contributing to IR carcinogenesis is the potential disruption of critical constraints that are imposed by normal cell interactions. To test this hypothesis, we asked whether IR affected the ability of nonmalignant human mammary epithelial cells (HMEC) to undergo tissue-specific morphogenesis in culture by using confocal microscopy and imaging bioinformatics. We found that irradiated single HMEC gave rise to colonies exhibiting decreased localization of E-cadherin, ?-catenin, and connexin-43, proteins necessary for the establishment of polarity and communication. Severely compromised acinar organization was manifested by the majority of irradiated HMEC progeny as quantified by image analysis. Disrupted cell–cell communication, aberrant cell–extracellular matrix interactions, and loss of tissue-specific architecture observed in the daughters of irradiated HMEC are characteristic of neoplastic progression. These data point to a heritable, nonmutational mechanism whereby IR compromises cell polarity and multicellular organization.

Park, Catherine C.; Henshall-Powell, Rhonda L.; Erickson, Anna C.; Talhouk, Rabih; Parvin, Bahram; Bissell, Mina J.; Barcellos-Hoff, Mary Helen



Revisit on dynamic radiation forces induced by pulsed Gaussian beams.  


Motivated by the recent optical trapping experiments using ultra-short pulsed lasers [Opt. Express 18, 7554 (2010); Appl. Opt. 48, G33 (2009)], in this paper we have re-investigated the trapping effects of the pulsed radiation force (PRF), which is induced by a pulsed Gaussian beam acting on a Rayleigh dielectric sphere. Based on our previous model [Opt. Express 15, 10615 (2007)], we have considered the effects arisen from both the transverse and axial PRFs, which lead to the different behaviors of both velocities and displacements of a Rayleigh particle within a pulse duration. Our analysis shows that, for the small-sized Rayleigh particles, when the pulse has the large pulse duration, it might provide the three-dimensional optical trapping; and when the pulse has the short pulse duration, it only provides the two-dimensional optical trapping with the axial movement along the pulse propagation. When the particle is in the vacuum or in the situation with the very weak Brownian motion, the particle can always be trapped stably due to the particle's cumulative momentum transferred from the pulse, and only in this case the trapping effect is independent of pulse duration. Finally, we have predicted that for the large-sized Rayleigh particles, the pulse beam can only provide the two-dimensional optical trap (optical guiding). Our results provide the important information about the trapping mechanism of pulsed tweezers. PMID:21934801

Wang, Li-Gang; Chai, Hai-Shui



Ultrasonic Measurement of Microdisplacement Induced by Acoustic Radiation Force  

NASA Astrophysics Data System (ADS)

Quantitative evaluation of human skin aging is achieved by measuring the viscoelasticity of the skin. In the present study, microdisplacement induced by acoustic radiation force (ARF) is quantitatively measured by high-frequency ultrasonography (HFUS) and the result is confirmed by laser-Doppler velocimetry (LDV). Poly(vinyl alcohol) (PVA) with 1% cellulose particles was used as the biological phantom. A concave piezoelectric zirconate titanate (PZT) transducer with a diameter and focal length of 3 cm was used as an applicator to generate ARF. Microdisplacement at each depth of PVA was measured by the phased tracking method at 100 MHz of ultrasound with a repetition rate of 2000 Hz. When 80 tone-burst pulses were applied, the displacement measured by HFUS was 9 ?m and the same result was obtained by LDV. As the displacement at each depth of PVA is measurable using ARF and the HFUS system, the system could be applied to measuring the viscoelasticity of the layered structure of the human skin.

Nagaoka, Ryo; Izumi, Takuya; Komatsu, Yosuke; Kobayashi, Kazuto; Saijo, Yoshifumi



Radiation induced oxidation of liquid alkanes as a polymer model  

NASA Astrophysics Data System (ADS)

Radiation induced oxidation of liquid n-hexadecane (n-C16H34) and squalane (C30H62) as a polymer model has been investigated by the measurements of the gas evolution and O2 uptake, and analyses of the oxidation products. Low O2 uptake, [G(-O2)~6.0] in liquid alkanes, indicates that the oxidation reaction does not exhibit chain kinetics, which is a big contrast to the process observed in solid, G(-O2)>> 10. H2 is the main gas product. More than 90% of the consumed O2 are converted into the oxidation products in liquid phase, mainly carboxylic acids, which is also a big contrast to the results of the radiolysis of liquid cyclohexane in the presence of O2 and thermal oxidation of hexadecane at elevated temperatures, where ketones and alcohols are major products at the initial stage. In the presence of aromatic additives, energy and charge transfer to the additives taking place despite the presence of O2 reduce the H2 evolution and the acid formation in parallel. Although hydroaromatic compounds act as an energy and charge scavenger, they are selectively oxidized through the donation of hydrogen in cyclic alkyl part attached to the phenyl ring, leading to large O2 uptake and corresponding ketone formation. From the comparison of the G-values of the O2 uptake, it was found that the oxidation reactions of liquid alkanes reflect well the oxidation of amorphous part in polymers.

Soebianto, Yanti S.; Katsumura, Yosuke; Ishigure, Kenkichi; Kubo, Junichi; Hamakawa, Satoshi; Kudoh, Hisaaki; Seguchi, Tadao



Dose rate effects on the radiation induced oxidation of polyethylene  

NASA Astrophysics Data System (ADS)

The yields and spatial distribution of the products arising from the in source oxidation of 50 ?m LDPE films induced by 60-Co gamma radiations and by 300 kev electrons have been investigated as a function of the dose rate. The dose rate was found to have a strong influence on the reaction, the hydroperoxides and carbonyls yields at the lowest gamma dose rate of 0.04 kGy/h being decreased by a factor of about three with increasing the gamma dose rate up to 0.69 kGy/h and by a factor of about 30 when operating at the e-beam dose rate of 1.5 kGy/s. The carbonyls depth concentration profiles, the EPR measurements on radicals intermediates and the experiments of post-irradiation oxidation are consistent with the conclusion that, as far as the gamma irradiation is concerned, the observed dose rate effects cannot be imputed to oxygen diffusion control and/or to the chain branching via hydroperoxides decomposition coupled to the longer times between the initiation events. The hypothesis of the dose rate acting on the kinetic chain length of the radioxidation which in turn implies a substantially uniform distribution of radicals in the amorphous phase attained through spur expansion is proposed.

Buttafava, A.; Tavares, A.; Arimondi, M.; Zaopo, A.; Nesti, S.; Dondi, D.; Mariani, M.; Faucitano, A.



Radiation-induced Vascular Lesions of the Skin: An Overview.  


Radiation-induced cutaneous vascular neoplasms occur infrequently and comprise benign, so-called atypical vascular lesions (AVL) and angiosarcomas (AS), often being high-grade malignant tumors. Both arise most frequently within previously irradiated skin in breast-conserving-treated mammary cancer patients. Because of the different clinical course and, consequently, different therapeutic approaches, histopathologic distinction of AVL and AS is essential but significant morphologic overlap has been documented. Furthermore, the coexistence of these lesions or progression of AVL into AS has rarely been reported. Whether AVL is a precursor of AS is much debated and unresolved to date. Recent interest has focused on genetic changes and their differences in AS and AVL. MYC amplification and expression of the corresponding protein has been identified in AS in comparison with AVL. Therefore, MYC fluorescent in situ hybridization and anti-MYC immunohistochemical analysis are diagnostically useful in difficult cases. Furthermore, advanced tailored treatment strategies in AS, one of the most aggressive type of sarcoma, rely on identifying genes and proteins involved in malignant angiogenesis. PMID:24113311

Flucke, Uta; Requena, Luis; Mentzel, Thomas



Radiation induced spent nuclear fuel dissolution under deep repository conditions.  


The dynamics of spent nuclear fuel dissolution in groundwater is an important part of the safety assessment of a deep geological repository for high level nuclear waste. In this paperwe discussthe most important elementary processes and parameters involved in radiation induced oxidative dissolution of spent nuclear fuel. Based on these processes, we also present a new approach for simulation of spent nuclear fuel dissolution under deep repository conditions. This approach accounts for the effects of fuel age, burn up, noble metal nanoparticle contents, aqueous H2 and HCO3- concentration, water chemistry, and combinations thereof. The results clearly indicate that solutes consuming H202 and combined effects of noble metal nanoparticles and H2 have significant impact on the rate of spent nuclear fuel dissolution. Using data from the two possible repository sites in Sweden, we have employed the new approach to estimate the maximum rate of spent nuclear fuel dissolution. This estimate indicates that H2 produced from radiolysis of groundwater alone will be sufficient to inhibit the dissolution completely for spent nuclear fuel older than 100 years. PMID:17993152

Jonsson, Mats; Nielsen, Fredrik; Roth, Olivia; Ekeroth, Ella; Nilsson, Sara; Hossain, Mohammad Mohsin



Nonlinear evolution of accretion disks induced by radiative feedback processes  

NASA Astrophysics Data System (ADS)

The existence of accretion disks around young stellar objects has recently become widely accepted. The luminosity of some young stellar objects is highly variable and is generally attributed to the release of gravitational energy from matter funneled onto them by accretion disks. The inward transport of matter through these disks is coupled to the outward transfer of angular momentum. This transfer is most likely to be regulated by the mixing of adjacent annuli through the process of large-scale turbulence. Most of the accretion energy generated by this process emerges near the inner edge of the disk. This radiation may be intercepted by the disk and may modify the vertical and viscous evolution of the disk itself. If surface heating can stabilize the disk against the dominant viscous process, then in systems with large accretion rates, angular momentum transport and mass flow through the disk will be quenched. Using this result, it is shown that such a mechanism can induce feedback through the disk which produces oscillations in the luminosity of the central object. This oscillation can become chaotic in certain regimes and might thus explain the highly variable nature of many T Tauri systems and their outbursting counterparts: the FU Orionis objects.

Bell, K. R.; Lin, D. N. C.; Ruden, Steven P.



Radiation-Induced Nano-Explosions at the Solid Surface: Near Surface Radiation Damage in CR-39 Polymer  

NASA Astrophysics Data System (ADS)

New measurements of fission fragment and alpha particle induced surface damage in the most sensitive and commonly used nuclear track detector CR-39 are presented here. Precisely designed and optimized exposure and chemical etching experiments are employed to unfold the structure of radiation induced surface damage (RISD). Delay in the startup of the chemical etching of latent tracks or surface radiation damage is measured and is found to contain important information about the structure of the surface damage. Simple atomic scale pictures of RISD and its chemical etching are developed in an empirical manner. Theoretical model and experimental findings coherently compose a realistic picture of early or femtosecond evolution of RISD.

Mukhtar, Ahmed Rana



Main chain liquid crystalline polytriazoles with aggregation-induced emission characteristics: click polymerization, mesomorphic packing, and solid state emission  

NASA Astrophysics Data System (ADS)

Biphenyl-containing diazides and diynes carrying tetraphenylethylene units are designed and synthesized. Their "click" polymerizations are initiated by Cu(PPh3)3Br in THF or DMF, affording soluble, regioregular polytriazoles in high yields (up to 94.8%) with narrow molecular weight distributions. The structures and properties of the polymers are evaluated and characterized by IR, NMR, UV, PL, TGA, DSC, POM and XRD measurements. All the polymers are almost nonluminescent when dissolved in solutions but become highly emissive when aggregated in poor solvents or fabricated as thin films in the solid state, displaying a novel phenomenon of aggregation-induced emission. The photophysical properties of the polymers are sensitive to their molecular structures and their solid-state quantum yields decrease with an increase in the spacer length. All the polymers enjoy high thermal stability, with 5% weight loss occurring at temperatures up to 406 °C. They are mesomorphic. While polymers with rigid main chains exhibit nematicity, those with longer spacer lengths show better mesogenic packing and hence form sematic phases at higher temperatures.

Yuan, Wang Zhang; Yu, Zhen Qiang; Lam, Jacky Wing Yip; Jim, Cathy K. W.; Tang, Ben Zhong



Radiation Recall Reaction Induced by Adjuvant Trastuzumab (Herceptin)  

PubMed Central

Although concerns of radiation sensitization have been raised with concurrent trastuzumab (Herceptin) administration, there has been no published case of radiation recall reaction associated with trastuzumab. This case describes a clinical presentation consistent with a radiation recall reaction following administration of adjuvant trastuzumab after neoadjuvant FEC-D chemotherapy and locoregional radiotherapy for HER2-positive, locally advanced breast cancer in a premenopausal woman. Although the mechanism and etiology of radiation recall dermatitis remain unclear, this case raises further hypotheses regarding a possible drug dose-dependence and possible predisposing risk factor for the development of radiation recall reactions.

Chung, Caroline; Stuart, David; Keyes, Mira



Radiation-induced metastable ordered phase in gallium nitride  

SciTech Connect

Energetic particle irradiation is one of the useful ways for realizing metastable phases far from the equilibrium state. In the present study, we performed electron-beam-irradiation into gallium nitride (GaN) with a wurtzite structure and examined its structural changes using transmission electron microscopy. It was found that superlattice Bragg reflections appear in the electron diffraction patterns of the irradiated GaN. This suggests that the wurtzite GaN transforms to another crystalline structure with atomic ordering.

Ishimaru, Manabu [Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047 (Japan)



Spinal Cord Glioblastoma Induced by Radiation Therapy of Nasopharyngeal Rhabdomyosarcoma with MRI Findings: Case Report  

PubMed Central

Radiation-induced spinal cord gliomas are extremely rare. Since the first case was reported in 1980, only six additional cases have been reported.; The radiation-induced gliomas were related to the treatment of Hodgkin's lymphoma, thyroid cancer, and medullomyoblastoma, and to multiple chest fluoroscopic examinations in pulmonary tuberculosis patient. We report a case of radiation-induced spinal cord glioblastoma developed in a 17-year-old girl after a 13-year latency period following radiotherapy for nasopharyngeal rhabdomyosarcoma. MRI findings of our case are described.

Ahn, Se Jin



Radiation induced apoptosis and initial DNA damage are inversely related in locally advanced breast cancer patients  

PubMed Central

Background DNA-damage assays, quantifying the initial number of DNA double-strand breaks induced by radiation, have been proposed as a predictive test for radiation-induced toxicity. Determination of radiation-induced apoptosis in peripheral blood lymphocytes by flow cytometry analysis has also been proposed as an approach for predicting normal tissue responses following radiotherapy. The aim of the present study was to explore the association between initial DNA damage, estimated by the number of double-strand breaks induced by a given radiation dose, and the radio-induced apoptosis rates observed. Methods Peripheral blood lymphocytes were taken from 26 consecutive patients with locally advanced breast carcinoma. Radiosensitivity of lymphocytes was quantified as the initial number of DNA double-strand breaks induced per Gy and per DNA unit (200 Mbp). Radio-induced apoptosis at 1, 2 and 8 Gy was measured by flow cytometry using annexin V/propidium iodide. Results Radiation-induced apoptosis increased in order to radiation dose and data fitted to a semi logarithmic mathematical model. A positive correlation was found among radio-induced apoptosis values at different radiation doses: 1, 2 and 8 Gy (p < 0.0001 in all cases). Mean DSB/Gy/DNA unit obtained was 1.70 ± 0.83 (range 0.63-4.08; median, 1.46). A statistically significant inverse correlation was found between initial damage to DNA and radio-induced apoptosis at 1 Gy (p = 0.034). A trend toward 2 Gy (p = 0.057) and 8 Gy (p = 0.067) was observed after 24 hours of incubation. Conclusions An inverse association was observed for the first time between these variables, both considered as predictive factors to radiation toxicity.



Radiation-Induced Heart Disease: A Clinical Update  

PubMed Central

Cardiovascular diseases and cancer are the two leading causes of morbidity and mortality worldwide. Improvement in cancer therapy has led to increasing number of cancer survivors, some of whom may suffer from adverse cardiovascular effects of radiation therapy. Longterm followup is essential, as the cardiac complication may manifest years after completion of radiation therapy. In this paper, we have discussed the cardiovascular effects of radiation therapy.

Yusuf, Syed Wamique; Sami, Shehzad; Daher, Iyad N.



MRI of radiation-induced tumors of the head and neck in post-radiation nasopharyngeal carcinoma.  


The aim of this study was to document the sites and MRI features of radiation-induced tumors (RITs) in the head and neck following treatment for nasopharyngeal carcinoma (NPC). The MRI examinations and clinical records of 20 patients with 21 RITs were reviewed retrospectively. RITs developed 3-30 years after radiotherapy and included eleven squamous cell carcinomas, six sarcomas, two neuroendocrine carcinomas, one mucoepidermoid carcinoma and one meningioma. RITs arose in the maxillary region (9), oro/hypopharynx and oral cavity (5), external auditory canal (4), nasopharynx and sphenoid sinus (2) and brain (1). Radiation-induced carcinoma and sarcoma had MRI features that were useful to distinguish them from recurrent NPC. To improve early detection of RITs, the check areas on an MRI of a patient with previous NPC treated by radiation should always include the maxillary region, tongue, and external auditory canal/temporal bone. PMID:19142643

Abrigo, Jill M; King, Ann D; Leung, Sing Fai; Vlantis, Alexander C; Wong, Jeffrey K T; Tong, Michael C F; Tse, Gary M K; Ahuja, Anil T



Predicting the radiation induced loss in Ge doped optical fibres at different temperatures  

Microsoft Academic Search

A new method is described for predicting radiation induced losses in Ge doped optical fibres at various temperatures. Some physical justification is given for the recovery model employed, and model calculations are compared with experimental results

R. H. West



Radiation induced oxidative degradation of ethylene-propylene rubber by IR spectroscopy.  

National Technical Information Service (NTIS)

IR absorption spectroscopy is a suitable technique to study degradation and damaging effects, induced by gamma radiation, on polymeric materials. The most important effects, crosslinking and oxidative degradation, influence IR spectra which are very sensi...

S. Baccaro U. Buontempo



Renal and Adrenal Factors in Radiation-Induced Hypertension and Nephrosclerosis.  

National Technical Information Service (NTIS)

Experiments were conducted in order to investigate the effects of adrenalectomy on the incidence, severity, and rate of progression of radiation-induced hypertension and nephrosclerosis in male rats. Adrenalectomized and non-adrenalectomized rats received...

A. G. Lurie



Amplification of scattered induced radiation flux in high-gain laser rods  

NASA Astrophysics Data System (ADS)

The spatial distribution of induced radiation flkux within a laser rod is determined through integrated investigations of the angular characteristics of the noisy induced radiation exiting the rod and the angular characteristics of the radiation scattering on its lateral surface. The measurements are made on neodymium activated yttrium aluminum garnet active elements in the form of a rod with a cylindrical surface and plane parallel polished ends. Antireflection coatings were applied to the ends of the elements to reduce reflection to approximately 0.1%. It is demonstrated that closed induced radiant fluxes for which lasing conditions are satisfied can form during strong scattering on the boundaries of the active medium. The stability of these fluxes depends strongly upon their orientation. The most stable fluxes are found to be those which scattered repeatedly at other than mirror angles. The occurrence of a halo of the induced radiation accompanying the occurrence of the generated mode is noted.

Skorobogatov, B. S.; Usoskin, A. I.



Immobilization of Yeast Cells with Hydrophilic Carrier by Radiation-Induced Polymerization.  

National Technical Information Service (NTIS)

Radiation-induced polymerization method was applied to the immobilization of yeast cells. The effects of irradiation, cooling and monomer, which are necessary for polymerization, were recovered completely by subsequent aerobical incubation of yeast cells....

T. Fujimura I. Kaetsu



Effect of Radiation-Induced Xerostomia on the Human Oral Microflora.  

National Technical Information Service (NTIS)

The caries-conducive impact of xerostomia was studied in 42 irradiated cancer patients. The radiation-induced xerostomia was paralleled by changes in the physical, microbial, biochemical, immunologic and dietary parameters of cariogenicity that collective...

S. Dreizen L. R. Brown



Direct Assays of Radiation Induced DNA Base Lesions in Mammalian Cells: Technical Progress Report.  

National Technical Information Service (NTIS)

HPLC techniques were used to separate, detect, identify and quantitate radiation-induced damage products of adenine (A)-containing model compounds and eukaryotic DNA. A library of 7 pure synthetic or isolated major damage products has been established con...

K. T. Wheeler



Radiation-induced bilateral optic neuropathy in cancer of the nasopharynx  

Microsoft Academic Search

Case Report  A case history of unanticipated radiation-induced bilateral optic neuropathy, 18 months after induction chemotherapy and radiation\\u000a therapy for a locally advanced nasopharyngeal carcinoma, is presented. Retrospective reanalysis of the radiation therapy technique,\\u000a with emphasis on the doses received by the optic pathway structures, was performed. These re-calculations revealed unexpectedly\\u000a high doses in the range 79 to 82 Gy (cumulative

Oda B. Wijers; Peter C. Levendag; Gre P. M. Luyten; Bert A. Bakker; Nicole J. M. Freling; Julie Klesman-Bradley; Evert Woudstra



Nanostructuring induced enhancement of radiation hardness in GaN epilayers  

SciTech Connect

The radiation hardness of as-grown and electrochemically nanostructured GaN epilayers against heavy ion irradiation was studied by means of photoluminescence (PL) and resonant Raman scattering (RRS) spectroscopy. A nanostructuring induced enhancement of the GaN radiation hardness by more than one order of magnitude was derived from the PL and RRS analyses. These findings show that electrochemical nanostructuring of GaN layers is a potentially attractive technology for the development of radiation hard devices.

Ursaki, V. V.; Tiginyanu, I. M.; Volciuc, O.; Popa, V.; Skuratov, V. A.; Morkoc, H. [Laboratory of Low-Dimensional Semiconductor Structures, Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau 2028 (Moldova, Republic of) and National Center for Materials Study and Testing, Technical University of Moldova, Chisinau 2004 (Moldova); Flerov Laboratory of Nuclear Reactions, Joint Institute for Nuclear Research, 141980 Dubna, Moscow region (Russian Federation); Department of Electrical and Computer Engineering, Virginia Commonwealth University, Richmond, Virginia 23284 and Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284 (United States)



Changes induced in spice paprika powder by treatment with ionizing radiation and saturated steam  

NASA Astrophysics Data System (ADS)

The changes in spice paprika powder induced by ionizing radiation, saturated steam (SS) and their combination were studied as a function of the absorbed radiation dose and the storage time. The SS treatment lead to a decrease in color content (lightening) after 12 weeks of storage, together with the persistence of free radicals and viscosity changes for a longer period. The results suggest that ionizing radiation is a more advantageous method as concerns preservation of the quality of spice paprika.

Kispéter, J.; Bajúsz-Kabók, K.; Fekete, M.; Szabó, G.; Fodor, E.; Páli, T.



Mechanisms of radiation-induced brain toxicity and implications for future clinical trials  

Microsoft Academic Search

Radiation therapy is widely used in the treatment of primary malignant brain tumors and metastatic tumors of the brain with\\u000a either curative or palliative intent. The limitation of cancer radiation therapy does not derive from the inability to ablate\\u000a tumor, but rather to do so without excessively damaging the patient. Among the varieties of radiation-induced brain toxicities,\\u000a it is the

Jae Ho Kim; Stephen L. Brown; Kenneth A. Jenrow; Samuel Ryu



Cell cycle alterations induced by isothermal 27 MHz radio-frequency radiation exposure  

Microsoft Academic Search

The purpose of this study was to test the hypothesis that 27 MHz continuous-wave radio-frequency radiation can alter the mammalian cell cycle in the absence of radiation-induced heating. Relative effects of r.f. radiation on specific phases of the cell cycle were determined by exposing synchronized Chinese hamster ovary (CHO) cells in G0\\/G1-, S- or G2\\/M-phase. The dose-rate dependence of r.f.

Guanghui Cao; Li-Ming Liu; Stephen F. Cleary



Investigation of the damage as induced by 1.7 MeV protons in an amorphous\\/crystalline silicon heterojunction solar cell  

Microsoft Academic Search

Current–voltage under illumination and quantum yield characteristics of an amorphous silicon\\/crystalline silicon hetero solar cell have been measured before and after exposure to high-energy (1.7MeV) protons. A comparison of the measured wavelength-dependent quantum yield with calculated values enabled to determine the effective electron diffusion length of the crystalline silicon, that dropped from a value of 434?m before to a value

Heinz-Christoph Neitzert; Patrizio Spinillo; Salvatore Bellone; Gian-Domenico Licciardi; Mario Tucci; Francesco Roca; Lucio Gialanella; Mario Romano



Radiation-induced versus endogenous DNA damage: possible effect of inducible protective responses in mitigating endogenous damage.  


Ionizing radiation (IR) causes damage to DNA that is apparently proportional to absorbed dose. The incidence of radiation-induced cancer in humans unequivocally rises with the value of absorbed doses above about 300 mGy, in a seemingly linear fashion. Extrapolation of this linear correlation down to zero-dose constitutes the linear-no-threshold (LNT) hypothesis of radiation-induced cancer incidence. The corresponding dose-risk correlation, however, is questionable at doses lower than 300 mGy. Non-radiation induced DNA damage and, in consequence, oncogenic transformation in non-irradiated cells arises from a variety of sources, mainly from weak endogenous carcinogens such as reactive oxygen species (ROS) as well as from micronutrient deficiencies and environmental toxins. In order to relate the low probability of radiation-induced cancer to the relatively high incidence of non-radiation carcinogenesis, especially at low-dose irradiation, the quantitative and qualitative differences between the DNA damages from non-radiation and radiation sources need to be addressed and put into context of physiological mechanisms of cellular protection. This paper summarizes a co-operative approach by the authors to answer the questions on the quantitative and qualitative DNA damages from non-radiation sources, largely endogenous ROS, and following exposure to low doses of IR. The analysis relies on published data and justified assumptions and considers the physiological capacity of mammalian cells to protect themselves constantly by preventing and repairing DNA damage. Furthermore, damaged cells are susceptible to removal by apoptosis or the immune system. The results suggest that the various forms of non-radiation DNA damage in tissues far outweigh corresponding DNA damage from low-dose radiation exposure at the level of, and well above, background radiation. These data are examined within the context of low-dose radiation induction of cellular signaling that may stimulate cellular protection systems over hours to weeks against accumulation of DNA damage. The particular focus is the hypothesis that these enhanced and persisting protective responses reduce the steady state level of non-radiation DNA damage, thereby reducing deleterious outcomes such as cancer and aging. The emerging model urgently needs rigorous experimental testing, since it suggests, importantly, that the LNT hypothesis is invalid for complex adaptive systems such as mammalian organisms. PMID:12856953

Pollycove, Myron; Feinendegen, Ludwig E



Development of an in vitro model for radiation-induced effects on oral keratinocytes  

Microsoft Academic Search

Changes in epithelial cell activity and the production of pro-inflammatory cytokines were examined utilizing an organotypic culture system as an in vitro model to study the effects of radiation on oral keratinocytes to simulate what is thought to occur in radiation-induced oral mucositis. Monolayer cultures of oral keratinocyte were irradiated by varying the dose. Cell injury was assessed using a

T. Tobita; K. Izumi; S. E. Feinberg



Radiation-induced degradation of water pollutants: State of the art  

Microsoft Academic Search

The radiation induced decomposition of biological resistant pollutants in drinking as well as in wastewater is shortly reviewed. First, some important units, deffinitions etc., radiation sources as well as dose depth curves in water as function of the electron energy and 60Co-?-rays are mentioned. It follows schematical presentation of water rediolysis and of characteristics of primary free radicals. After that

Nikola Getoff



Radiation-induced otitis media—study of a new test, vestibular-evoked myogenic potential  

Microsoft Academic Search

PurposeExcluding the radiation history, current physical examination and audiovestibular function tests fail to differentiate radiation-induced otitis media (ROM) from chronic otitis media (COM). This study applied the newly developed vestibular-evoked myogenic potential (VEMP) test to investigate whether the VEMP test can be of help in differentiating between them.

Tsung-Lin Yang; Yi-Ho Young



Experimental and theoretical investigations of electromagnetic radiation induced by rock fracture  

Microsoft Academic Search

Frid, V., Bahat, D., Goldbaum, J., Rabinovitch, A. 2000. Experimental and theoretical investigations of electromagnetic radiation induced by rock fracture. Isr. J. Earth Sci. 49: 9-19. There is a general agreement in the literature that the technique of measuring electro- magnetic radiation (EMR) emitted from cracked rock is a good candidate for forecast- ing of earthquakes. Our immediate objective in

Dov Bahat; Julia Goldbaum; Vladimir Frid; Avinoam Rabinovitcha; Avinoam Rabinovitch



Late treatment with imatinib mesylate ameliorates radiation-induced lung fibrosis in a mouse model  

Microsoft Academic Search

BACKGROUND: We have previously shown that small molecule PDGF receptor tyrosine kinase inhibitors (RTKI) can drastically attenuate radiation-induced pulmonary fibrosis if the drug administration starts at the time of radiation during acute inflammation with present but limited effects against acute inflammation. To rule out interactions of the drug with acute inflammation, we investigated here in an interventive trial if a

Minglun Li; Amir Abdollahi; Hermann-Josef Gröne; Kenneth E Lipson; Claus Belka; Peter E Huber



Mitotic Delay induced by Gamma Radiation in Broad Bean Root Meristems  

Microsoft Academic Search

IN attempting to interpret quantitative data on the yield of structural changes induced in chromosomes by radiation, the difficulty arises with material containing cells in random stages of development, as in root tips, that a given dose of radiation delays the arrival of cells at metaphase to an unknown extent. There is thus an uncertainty as to the developmental stage

G. J. Neary; H. J. Evans; S. M. Tonkinson




Microsoft Academic Search

PurposeDuring clinical care in the University of Chicago renal cell carcinoma program there was 1 case of prior radiation therapy for a neuroblastoma (patient age 16 months). After this index case was found our investigation was conducted to identify other cases with apparent radiation therapy induced renal cell carcinoma and review the literature on the subject.




Radiation Induced Non-targeted Response: Mechanism and Potential Clinical Implications  

PubMed Central

Generations of students in radiation biology have been taught that heritable biological effects require direct damage to DNA. Radiation-induced non-targeted/bystander effects represent a paradigm shift in our understanding of the radiobiological effects of ionizing radiation in that extranuclear and extracellular effects may also contribute to the biological consequences of exposure to low doses of radiation. Although radiation induced bystander effects have been well documented in a variety of biological systems, including 3D human tissue samples and whole organisms, the mechanism is not known. There is recent evidence that the NF-?B-dependent gene expression of interleukin 8, interleukin 6, cyclooxygenase-2, tumor necrosis factor and interleukin 33 in directly irradiated cells produced the cytokines and prostaglandin E2 with autocrine/paracrine functions, which further activated signaling pathways and induced NF-?B-dependent gene expression in bystander cells. The observations that heritable DNA alterations can be propagated to cells many generations after radiation exposure and that bystander cells exhibit genomic instability in ways similar to directly hit cells indicate that the low dose radiation response is a complex interplay of various modulating factors. The potential implication of the non-targeted response in radiation induced secondary cancer is discussed. A better understanding of the mechanism of the non-targeted effects will be invaluable to assess its clinical relevance and ways in which the bystander phenomenon can be manipulated to increase therapeutic gain in radiotherapy.

Hei, Tom K.; Zhou, Hongning; Chai, Yunfei; Ponnaiya, Brian; Ivanov, Vladimir N.



Apoptosis in mesangial cells induced by ionizing radiation and cytotoxic drugs  

Microsoft Academic Search

Apoptosis in mesangial cells induced by ionizing radiation and cytotoxic drugs. Mesangial proliferation contributes to the pathogenesis of many forms of glomerulonephritis. To evaluate the role of apoptosis on the pharmacologic effects of cytotoxic drugs and ionizing radiation, we studied their effects on cultured rat mesangial cells (MC), whose apoptotic response to these drugs is unknown. Mesangial cells were cultured

Dae Ryong Cha; Stella M Feld; Cynthia Nast; Janine LaPage; Sharon G Adler



Superoxide dismutase and radiation-induced haemolysis: no benefit of its increased content in red cells.  


The sensitivity of human erythrocytes with normal and increased activity of superoxide dismutase (SOD) was compared under different types of oxidative stress. Red blood cells with increased SOD activity were more resistant to haemolysis induced by photoactivated riboflavin but no more resistant to radiation-induced haemolysis and acetylphenylhydrazine stress. These results indicate a negligible role of O(2) in mediation of the haemolytic action of ionizing radiation. PMID:6968737

Bartosz, G; Leyko, W; Kedziora, J; Jeske, J



Serum amyloid P ameliorates radiation-induced oral mucositis and fibrosis  

Microsoft Academic Search

PURPOSE: To evaluate the effect of the anti-fibrotic protein serum amyloid P (SAP) on radiation-induced oral mucositis (OM) and fibrosis in a hamster cheek-pouch model. EXPERIMENTAL DESIGN: Hamsters received a single dose of radiation (40 Gy) to the left everted cheek pouch to induce significant OM. The protective therapeutic potential of SAP was evaluated using varying dosing regimens. The extent

Lynne A Murray; Michael S Kramer; David P Hesson; Brynmor A Watkins; Edward G Fey; Rochelle L Argentieri; Furquan Shaheen; Darryl A Knight; Stephen T Sonis



Idiopathic and Radiation-Induced Ocular Telangiectasia: The Involvement of the ATM Gene  

Microsoft Academic Search

PURPOSE. To investigate whether individuals, with no family history of ataxia telangiectasia (AT), in whom idiopathic or radiation-induced ocular telangiectasia developed are carriers of ATM gene mutations. METHODS. The ATM cDNA from lymphoblastoid cell lines estab- lished from 16 patients with idiopathic retinal or choroidal telan- giectasia and 14 patients with radiation-induced telangiectasia after radiotherapy for age-related macular degeneration (AMD)

Martine Mauget-Faysse; Michele Vuillaume; Maddalena Quaranta; Norman Moullan; Sandra Angele; Marlin D. Friesen; Janet Hall



Application of Formaldehyde for Treatment of Hemorrhagic Radiation-Induced Proctitis  

Microsoft Academic Search

. Radiation-induced proctitis with hemorrhage is not a common complication of radiotherapy to the pelvis for carcinoma.\\u000a In the most severe forms, massive hemorrhage may necessitate repeated transfusions and inpatient treatment. In severe cases\\u000a medical treatment has not been proved effective. Surgery may lead to serious complications and is technically difficult. Six\\u000a patients who showed a hemorrhagic radiation-induced proctitis have

B. Roche; R. Chautems; M. C. Marti



Radiation-induced chromosome damage in human lymphocytes  

Microsoft Academic Search

ABSTRACT Analysis for chromosome aberrations in human peripheral blood lymphocytes has been developed as an indicator of dose from ionising radiation. This paper outlines the mechanism of production of aberrations, the technique for their analysis and the dose-effect relationships for various types of radiation. During the past ten years the National Radiological Protection Board has developed a service for the

D. C. Lloyd; G. W. Dolphin



Minimizing Radiation-induced Skin Injury in Interventional Radiology Procedures.  

National Technical Information Service (NTIS)

Skin injury is a deterministic effect of radiation. Once a threshold dose has been exceeded, the severity of the radiation effect at any point on the skin increases with increasing dose. Peak skin dose is defined as the highest dose delivered to any porti...

D. L. Miller J. D. Georgia P. T. Noonan S. Balter



Electrostatic origin of in vitro aggregation of human ?-crystallin.  


The proteins ?-, ?-, and ?-crystallins are the major components of the lens in the human eye. Using dynamic light scattering method, we have performed in vitro investigations of protein-protein interactions in dilute solutions of human ?-crystallin and ?-crystallin. We find that ?-crystallin spontaneously aggregates into finite-sized clusters in phosphate buffer solutions. There are two distinct populations of unaggregated and aggregated ?-crystallins in these solutions. On the other hand, ?-crystallin molecules are not aggregated into large clusters in solutions of ?-crystallin alone. When ?-crystallin and ?-crystallin are mixed in phosphate buffer solutions, we demonstrate that the clusters of ?-crystallin are prevented. By further investigating the roles of temperature, protein concentration, pH, salt concentration, and a reducing agent, we show that the aggregation of ?-crystallin under our in vitro conditions arises from non-covalent electrostatic interactions. In addition, we show that aggregation of ?-crystallin occurs under the dilute in vitro conditions even in the absence of oxidizing agents that can induce disulfide cross-links, long considered to be responsible for human cataracts. Aggregation of ?-crystallin when maintained under reducing conditions suggests that oxidation does not contribute to the aggregation in dilute solutions. PMID:24089726

Mohr, Benjamin G; Dobson, Cassidy M; Garman, Scott C; Muthukumar, Murugappan



Electrostatic origin of in vitro aggregation of human ?-crystallin  

NASA Astrophysics Data System (ADS)

The proteins ?-, ?-, and ?-crystallins are the major components of the lens in the human eye. Using dynamic light scattering method, we have performed in vitro investigations of protein-protein interactions in dilute solutions of human ?-crystallin and ?-crystallin. We find that ?-crystallin spontaneously aggregates into finite-sized clusters in phosphate buffer solutions. There are two distinct populations of unaggregated and aggregated ?-crystallins in these solutions. On the other hand, ?-crystallin molecules are not aggregated into large clusters in solutions of ?-crystallin alone. When ?-crystallin and ?-crystallin are mixed in phosphate buffer solutions, we demonstrate that the clusters of ?-crystallin are prevented. By further investigating the roles of temperature, protein concentration, pH, salt concentration, and a reducing agent, we show that the aggregation of ?-crystallin under our in vitro conditions arises from non-covalent electrostatic interactions. In addition, we show that aggregation of ?-crystallin occurs under the dilute in vitro conditions even in the absence of oxidizing agents that can induce disulfide cross-links, long considered to be responsible for human cataracts. Aggregation of ?-crystallin when maintained under reducing conditions suggests that oxidation does not contribute to the aggregation in dilute solutions.

Mohr, Benjamin G.; Dobson, Cassidy M.; Garman, Scott C.; Muthukumar, Murugappan



Prophylaxis and management of acute radiation-induced skin reactions: a systematic review of the literature  

PubMed Central

Radiation therapy is a common treatment for cancer patients. One of the most common side effects of radiation is acute skin reaction (radiation dermatitis) that ranges from a mild rash to severe ulceration. Approximately 85% of patients treated with radiation therapy will experience a moderate-to-severe skin reaction. Acute radiation-induced skin reactions often lead to itching and pain, delays in treatment, and diminished aesthetic appearance—and subsequently to a decrease in quality of life. Surveys have demonstrated that a wide variety of topical, oral, and intravenous agents are used to prevent or to treat radiation-induced skin reactions. We conducted a literature review to identify trials that investigated products for the prophylaxis and management of acute radiation dermatitis. Thirty-nine studies met the pre-defined criteria, with thirty-three being categorized as prophylactic trials and six as management trials. For objective evaluation of skin reactions, the Radiation Therapy Oncology Group criteria and the U.S. National Cancer Institute Common Toxicity Criteria were the most commonly used tools (65% of the studies). Topical corticosteroid agents were found to significantly reduce the severity of skin reactions; however, the trials of corticosteroids evaluated various agents, and no clear indication about a preferred corticosteroid has emerged. Amifostine and oral enzymes were somewhat effective in preventing radiation-induced skin reactions in phase ii and phase iii trials respectively; further large randomized controlled trials should be undertaken to better investigate those products. Biafine cream (Ortho–McNeil Pharmaceuticals, Titusville, NJ, U.S.A.) was found not to be superior to standard regimes in the prevention of radiation-induced skin reactions (n = 6). In conclusion, the evidence is insufficient to support the use of a particular agent for the prevention and management of acute radiation-induced skin reactions. Future trials should focus on comparing agents and approaches that, in phase i and ii trials, suggest efficacy. These future phase iii randomized controlled trials must clearly distinguish between preventive and management strategies for radiation-induced dermatitis. Only then can evidence-based guidelines be developed, with the hope of standardizing the approach across centres and of improving the prevention and management of radiation-induced dermatitis.

Salvo, N.; Barnes, E.; van Draanen, J.; Stacey, E.; Mitera, G.; Breen, D.; Giotis, A.; Czarnota, G.; Pang, J.; De Angelis, C.



Protection by S-2-(3-aminopropylamino)ethylphosphorothioic acid against radiation-induced leg contractures in mice. [Gamma Radiation  

SciTech Connect

S-2-(3-Aminopropylamino)ethylphosphorothioic acid (WR-2721) was shown to provide marked protection against development of radiation-induced leg contractures in C3Hf/Kam mice whose legs were exposed to single doses of gamma-radiation. The radiation doses ranged from 3300 to 6200 rads delivered to the right hind thighs from two parallelly opposed 137Cs sources. WR-2721 was given i.p. 30 min before irradiation. The severity of radiation-induced leg contractures in untreated and WR-2721-treated mice was followed for 342 days after irradiation. The degree of leg contractures in both control and WR-2721-treated mice increased up to 100 days after radiation, when the change stabilized, remaining more or less at the same level to the end of the observation period. During this entire period, the severity of contractures was less in WR-2721-treated mice. The dose-modifying factor for the level of 5 mm reduction in leg extension was 1.5 at 182 days after irradiation. Since WR-2721 did not prevent the radiocurability of 8-mm fibrosarcomas growing in the same legs, these data imply that WR-2721 has a high potential for increasing therapeutic gain when combined with irradiation in the treatment of tumors of an appreciable size.

Hunter, N.; Milas, L.



Multiple dynamic scattering of laser radiation on a light-induced jet of microparticles in suspension  

SciTech Connect

A self-consistent theoretical analysis is made of the multiple scattering of coherent laser radiation in a random medium under conditions of formation of a light-induced jet of scatterers. It is shown, that the laser particle acceleration leads to a qualitative change of the temporal auto-correlation function of scattered light as compared to the case of scattering on chaotically moving Brownian particles. The effect of radiation absorption on the temporal coherence of the multiple-scattered light under conditions of light-induced particle motion in the scattering medium is studied. (scattering and reflection of laser radiation)

Skipetrov, S E [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Chesnokov, S S [Department of Physics, M.V. Lomonosov Moscow State University, Moscow (Russian Federation); Zakharov, S D; Kazaryan, M A; Korotkov, N P; Shcheglov, V A [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)



Evidence that ultraviolet B radiation induces tolerance and impairs induction of contact hypersensitivity by different mechanisms.  

PubMed Central

Tumour necrosis factor-alpha (TNF-alpha) and cis-urocanic acid (UCA) have recently been implicated in the process by which ultraviolet B radiation (UVB) impairs the induction of contact hypersensitivity when dinitrofluorobenzene (DNFB) is painted on UVB-exposed skin. The evidence supports the hypothesis that UVB radiation converts trans- to cis-UCA in the epidermis which in turn causes the epidermis of UVB-susceptible mice to produce/contain excessive local amounts of TNF-alpha. When hapten is painted on TNF-alpha- or UVB-treated skin, contact hypersensitivity fails to develop. As UVB radiation also induces hapten-specific tolerance and suppressor T cells when hapten is applied to UVB-exposed skin of UVB-susceptible strains of mice, we examined whether TNF-alpha and/or UVB-irradiated UCA (UV-UCA) might be similarly involved in the mechanism by which UVB induces tolerance. We report that intracutaneously-injected TNF-alpha and UV-UCA altered the cutaneous environment such that when DNFB was painted on the injected site, hapten-specific tolerance was induced and suppressor cells were generated. However, the tolerance induced by UVB radiation and the tolerance that followed intracutaneous injection of UV-UCA were not reversed by neutralizing anti-TNF-alpha antibodies. Moreover, UV-UCA and TNF-alpha-induced tolerance and suppressor cells in both UVB-susceptible (UVB-S) and UVB-resistant mice, whereas UVB radiation induced tolerance only in UVB-S mice. We conclude that the mechanism by which UVB radiation induces tolerance in mice is separate and distinct from the mechanism by which UVB radiation impairs contact hypersensitivity induction. Moreover, our data support the view that the generation of suppressor cells and the development of hapten-specific tolerance may be mechanistically distinct. The possible molecular and cellular mediators of UVB-induced tolerance are discussed.

Shimizu, T; Streilein, J W



Radiation-induced large intracranial vessel occlusive vasculopathy  

SciTech Connect

Two patients who developed large intracranial vessel occlusion after standard radiation therapy for brain tumor are described. This form of vascular occlusion is usually seen in patients who have previously been treated by radiotherapy for intracranial tumor who then develop a relatively acute change in neurologic status. Histology of the lesion mimics accelerated focal arteriosclerosis. The clinical and radiographic manifestations of one case were highly atypical. The vasculopathy became evident shortly after termination of radiation therapy for a fourth ventricular ependymoma, and the angiographic picture stimulated a diffuse arteritis. The second patient was more typical, with clinical symptoms developing 12 years after radiation therapy for an oligodendroglioma. Occlusion of a proximal vessel that had been included in the radiation port was demonstrated radiographically and confirmed by pathologic examination. The clinical, angiographic, and histologic features of these two cases are discussed and previously reported cases are reviewed.

Brant-Zawadzki, M.; Anderson, M.; DeArmond, S.J.; conley, F.K.; Jahnke, R.W.



Relation Between Four Types of Radiation Damage and Induced Repair.  

National Technical Information Service (NTIS)

Four strains of Escherichia coli were exposed to uv and gamma radiation. Procedures are described for mutational studies, classification of revertants, inhibition of postirradiation DNA degradation and radioresistance. Comparisons were made of induction o...

M. L. Radar



Radiation induced degradation of EPR by IR oxidation profiling.  

National Technical Information Service (NTIS)

Infrared absorption spectroscopy was used to investigate the effect of gamma-radiation on an ethylene-propylene copolymer loaded with different amounts of antioxidant. The oxidation profiles were obtained by analyzing slices of the samples with an IR micr...

S. Baccaro P. D'Atanasio U. Buontempo



Anti-apoptotic peptides protect against radiation-induced cell death  

SciTech Connect

The risk of terrorist attacks utilizing either nuclear or radiological weapons has raised concerns about the current lack of effective radioprotectants. Here it is demonstrated that the BH4 peptide domain of the anti-apoptotic protein Bcl-xL can be delivered to cells by covalent attachment to the TAT peptide transduction domain (TAT-BH4) and provide protection in vitro and in vivo from radiation-induced apoptotic cell death. Isolated human lymphocytes treated with TAT-BH4 were protected against apoptosis following exposure to 15 Gy radiation. In mice exposed to 5 Gy radiation, TAT-BH4 treatment protected splenocytes and thymocytes from radiation-induced apoptotic cell death. Most importantly, in vivo radiation protection was observed in mice whether TAT-BH4 treatment was given prior to or after irradiation. Thus, by targeting steps within the apoptosis signaling pathway it is possible to develop post-exposure treatments to protect radio-sensitive tissues.

McConnell, Kevin W. [Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110 (United States); Muenzer, Jared T. [Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110 (United States); Chang, Kathy C. [Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Davis, Chris G. [Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); McDunn, Jonathan E. [Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Coopersmith, Craig M. [Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110 (United States); Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Hilliard, Carolyn A. [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Hotchkiss, Richard S. [Department of Surgery, Washington University School of Medicine, St. Louis, MO 63110 (United States); Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Grigsby, Perry W. [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110 (United States); Hunt, Clayton R. [Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO 63110 (United States)]. E-mail:



Radiation?Induced Synthesis of Fullerene?Silica Hybrid Nanomaterials  

Microsoft Academic Search

C60 fullerene has been radiation grafted on bare and functionalized silica surface with mercaptopropyl moieties in toluene solution. The resulting fullerene?silica hybrid nanomaterials have been characterized by FT?IR and solid state C CP?MAS NMR spectroscopy and compared to the radiolysis products of C60 in toluene. It has been found that fullerene is grafted on silica surface but, because the radiation

Franco Cataldo; Giancarlo Angelini; Edo Lilla; Ornella Ursini



Experimental observation of laser-induced radiation heat waves  

Microsoft Academic Search

The propagation of a radiation heat wave through a thin foil of solid gold was investigated experimentally. The wave is driven by the intense thermal radiation in 1-3-mm-diam gold cavities heated by an intense laser pulse (duration 0.8-0.9 ns, wavelength 0.35 mum) to temperatures of more than 200 eV. Evidence of the propagating wave was obtained from the delayed onset

R. Sigel; G. D. Tsakiris; F. Lavarenne; J. Massen; R. Fedosejevs; J. Meyer-Ter-Vehn; M. Murakami; K. Eidmann; S. Witkowski; H. Nishimura; Y. Kato; H. Takabe; T. Endo; K. Kondo; H. Shiraga; S. Sakabe; T. Jitsuno; M. Takagi; C. Yamanaka; S. Nakai



Electromagnetic radiation induced current steps in ? biepitaxial Josephson junctions  

Microsoft Academic Search

Ordinary Shapiro steps were observed in the I - V curves of biepitaxial Josephson junctions at 0953-2048\\/10\\/11\\/002\\/img7 when microwave radiation at f = 11 GHz was applied to the junction. However, pronounced current steps were observed at twice the period, 0953-2048\\/10\\/11\\/002\\/img8 when the d.c. Josephson current was suppressed by high power microwave radiation. The extension of the voltage region, within

Yu A. Boikov; Z. G. Ivanov; T. Claeson



Radioprotection from radiation-induced lymphedema without tumor protection.  


Lymphedema or tissue swelling from impaired lymph drainage commonly occurs after regional nodal dissection and/or radiation therapy for cancer control. Treatment options for this disabling and life-altering complication involve long-term labor-intensive commitments. Sentinel node biopsy can forestall removal of negative regional nodes, offering some protection against lymphedema, however, most preventive measures are elusive, ineffective, or unproven. Our goal was to determine whether the radioprotectant amifostine could prevent or retard the development of lymphedema in a rodent radiation therapy-dependent model yet not offer tumor protection from the therapeutic effects of radiation therapy. We pre-treated rats after unilateral radical groin dissection with the organic thiophosphate radioprotectant amifostine or placebo prior to single dose post-operative groin radiation therapy and monitored hindlimb volumes, wound scores, and tissue lymphostasis. In addition, we determined whether amifostine protected human MCF7 breast cancer cells exposed to a range of radiation therapy doses in an in vitro clonogenic assay and an in vivo MCF7 tumor xenograft model. Our findings indicate that amifostine markedly reduced the volume of limb lymphedema and dramatically improved wound healing and tissue lymphostasis in the rodent lymphedema model. The in vivo and in vitro studies further demonstrated that amifostine offered no MCF7 tumor protection from radiation therapy. These pre-clinical findings provide proof-of-principle to further delineate specific mechanisms underlying amifostine's beneficial effects, determine optimal amifostine-radiation therapy dosing regimens, and thereby expedite translation into clinical trials to reduce lymphedema incidence and severity in cancer patients at high lymphedema risk in whom radiation therapy is the recommended therapy. PMID:20848992

Daley, S K; Bernas, M J; Stea, B D; Bracamonte, F; McKenna, M; Stejskal, A; Hirleman, E D; Witte, M H



Amelioration of ionizing radiation induced lipid peroxidation in mouse liver by Moringa oleifera Lam. leaf extract.  


Protective effect of Moringa oleifera leaf extract (MoLE) against radiation-induced lipid peroxidation has been investigated. Swiss albino mice, selected from an inbred colony, were administered with MoLE (300 mg/kg body wt) for 15 days before exposing to a single dose of 5 Gy 60Co-gamma radiation. After treatments, animals were necropsied at different post irradiation intervals (days 1, 7 and 15) and hepatic lipid peroxidation and reduced glutathione (GSH) contents were estimated to observe the relative changes due to irradiation and its possible amelioration by MoLE. It was observed that, MoLE treatment restored GSH in liver and prevented radiation induced augmentation in hepatic lipid peroxidation. Phytochemical analysis showed that MoLE possess various phytochemicals such as ascorbic acid, phenolics (catechin, epicatechin, ferulic acid, ellagic acid, myricetin) etc., which may play the key role in prevention of hepatic lipid peroxidation by scavenging radiation induced free radicals. PMID:22439436

Sinha, Mahuya; Das, Dipesh Kr; Datta, Sanjukta; Ghosh, Santinath; Dey, Sanjit



Phytochemicals for prevention of solar ultraviolet radiation-induced damages.  


While solar light is indispensable for sustenance of life, excessive exposure can cause several skin-related disorders. The UV part of solar radiation, in particular, is linked to disorders ranging from mild inflammatory effects of the skin to as serious as causing several different types of cancers. Changes in lifestyle together with depletion in the atmospheric ozone layer during the last few decades have led to an increase in the incidence of skin cancer. Skin cancers consisting of basal and squamous cell carcinomas are especially linked to the UVB part of solar radiation. Reducing excessive exposure to solar radiation is desirable; however, as this approach is unavoidable, it is suggested that other novel strategies be developed to reduce the effects of solar radiation to skin. One approach to reduce the harmful effects of solar radiation is through the use of phytochemicals, an approach that is popularly known as "Photochemoprotection." In recent years many phytochemicals with potential antioxidant properties have been identified and found to be photoprotective in nature. We describe here some of the most popular phytochemicals being studied that have the potential to reduce the harmful effects associated with solar UV radiation. PMID:18266816

Adhami, Vaqar M; Syed, Deeba N; Khan, Naghma; Afaq, Farrukh




PubMed Central

1. Crystalline hexokinase has been isolated from baker's yeast. 2. Crystalline hexokinase is a protein of albumin type of a molecular weight of 96,000. Its isoelectric point is at about pH 4.8. 3. The method of isolation consists in separating the proteins of an aqueous extract of toluene-treated yeast by means of fractional precipitation with ammonium sulfate and with alcohol. 4. The procedure involves also the separation of several crystalline proteins, including one yellow crystalline protein, which do not possess hexokinase activity. The biological and the physicochemical properties of these proteins are still under investigation. 5. The crystallization of hexokinase proceeds at about 5°C. in the presence of ammonium sulfate and dilute phosphate buffer pH 7.0. 6. Crystalline hexokinase becomes relatively pure after 2 or 3 recrystallizations as tested by solubility, sedimentation in the ultracentrifuge, and electrophoresis. The enzymatic activity remains constant on repeated crystallization. 7. The enzymatic activity is associated with the protein nature of the material. Inactivation is accompanied by denaturation of the protein. 8. Crystalline hexokinase is relatively stable when stored in the form of crystalline filter cake. Solutions of hexokinase in dilute buffers are most stable at pH 5.0. 9. Crystalline hexokinase requires the presence of magnesium ions for its catalytic activity.

Kunitz, M.; McDonald, Margaret R.



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

NASA Astrophysics Data System (ADS)

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

Plaza-Rosado, Heriberto



Radiation-induced lung injury is mitigated by blockade of gastrin-releasing peptide.  


Gastrin-releasing peptide (GRP), secreted by pulmonary neuroendocrine cells, mediates oxidant-induced lung injury in animal models. Considering that GRP blockade abrogates pulmonary inflammation and fibrosis in hyperoxic baboons, we hypothesized that ionizing radiation triggers GRP secretion, contributing to inflammatory and fibrotic phases of radiation-induced lung injury (RiLI). Using C57BL/6 mouse model of pulmonary fibrosis developing ?20 weeks after high-dose thoracic radiation (15 Gy), we injected small molecule 77427 i.p. approximately 1 hour after radiation then twice weekly for up to 20 weeks. Sham controls were anesthetized and placed in the irradiator without radiation. Lung paraffin sections were immunostained and quantitative image analyses performed. Mice exposed to radiation plus PBS had increased interstitial CD68(+) macrophages 4 weeks after radiation and pulmonary neuroendocrine cells hyperplasia 6 weeks after radiation. Ten weeks later radiation plus PBS controls had significantly increased pSmad2/3(+) nuclei/cm(2). GRP blockade with 77427 treatment diminished CD68(+), GRP(+), and pSmad2/3(+) cells. Finally, interstitial fibrosis was evident 20 weeks after radiation by immunostaining for ?-smooth muscle actin and collagen deposition. Treatment with 77427 abrogated interstitial ?-smooth muscle actin and collagen. Sham mice given 77427 did not differ significantly from PBS controls. Our data are the first to show that GRP blockade decreases inflammatory and fibrotic responses to radiation in mice. GRP blockade is a novel radiation fibrosis mitigating agent that could be clinically useful in humans exposed to radiation therapeutically or unintentionally. PMID:23395092

Zhou, Shutang; Nissao, Esther; Jackson, Isabel L; Leong, Wei; Dancy, Lindsay; Cuttitta, Frank; Vujaskovic, Zeljko; Sunday, Mary E



Protective effects of L-selenomethionine on space radiation induced changes in gene expression.  


Ionizing radiation can produce adverse biological effects in astronauts during space travel. Of particular concern are the types of radiation from highly energetic, heavy, charged particles known as HZE particles. The aims of our studies are to characterize HZE particle radiation induced biological effects and evaluate the effects of L-selenomethionine (SeM) on these adverse biological effects. In this study, microarray technology was used to measure HZE radiation induced changes in gene expression, as well as to evaluate modulation of these changes by SeM. Human thyroid epithelial cells (HTori-3) were irradiated (1 GeV/n iron ions) in the presence or in the absence of 5 microM SeM. At 6 h post-irradiation, all cells were harvested for RNA isolation. Gene Chip U133Av2 from Affymetrix was used for the analysis of gene expression, and ANOVA and EASE were used for a determination of the genes and biological processes whose differential expression is statistically significant. Results of this microarray study indicate that exposure to small doses of radiation from HZE particles, 10 and 20 cGy from iron ions, induces statistically significant differential expression of 196 and 610 genes, respectively. In the presence of SeM, differential expression of 77 out of 196 genes (exposure to 10 cGy) and 336 out of 610 genes (exposure to 20 cGy) is abolished. In the presence or in the absence of SeM, radiation from HZE particles induces differential expression of genes whose products have roles in the induction of G1/S arrest during the mitotic cell cycle, as well as heat shock proteins. Some of the genes, whose expressions were affected by radiation from HZE particles and were unchanged in irradiated cells treated with SeM, have been shown to have altered expression levels in cancer cells. The conclusions of this report are that radiation from HZE particles can induce differential expression of many genes, some of which are known to play roles in the same processes that have been shown to be activated in cells exposed to radiation from photons (like cell cycle arrest in G1/S), and that supplementation with SeM abolishes HZE particle-induced differential expression of many genes. Understanding the roles that these genes play in the radiation-induced transformation of cells may help to decipher the origins of radiation-induced cancer. PMID:17265150

Stewart, J; Ko, Y-H; Kennedy, A R



Apo2 Ligand\\/TNF-related Apoptosis-inducing Ligand and Death Receptor 5 Mediate the Apoptotic Signaling Induced by Ionizing Radiation in Leukemic Cells1  

Microsoft Academic Search

Ionizing radiation is a major tool for cancer treatment. The response of eukaryotic cells to ionizing radiation includes apoptosis, a process which requires activation of multiple genes. We sought to determine whether radiation-induced gene expression plays a role in radiation-induced apoptosis. We found Apo2 ligand (Apo2L, also called TRAIL) mRNA induction following g-irradiation of Jurkat, MOLT-4, CEM, and PBMC, all

Bendi Gong; Alex Almasan



Effect of ozone oxidative preconditioning in preventing early radiation-induced lung injury in rats.  


Ionizing radiation causes its biological effects mainly through oxidative damage induced by reactive oxygen species. Previous studies showed that ozone oxidative preconditioning attenuated pathophysiological events mediated by reactive oxygen species. As inhalation of ozone induces lung injury, the aim of this study was to examine whether ozone oxidative preconditioning potentiates or attenuates the effects of irradiation on the lung. Rats were subjected to total body irradiation, with or without treatment with ozone oxidative preconditioning (0.72 mg/kg). Serum proinflammatory cytokine levels, oxidative damage markers, and histopathological analysis were compared at 6 and 72 h after total body irradiation. Irradiation significantly increased lung malondialdehyde levels as an end-product of lipoperoxidation. Irradiation also significantly decreased lung superoxide dismutase activity, which is an indicator of the generation of oxidative stress and an early protective response to oxidative damage. Ozone oxidative preconditioning plus irradiation significantly decreased malondialdehyde levels and increased the activity of superoxide dismutase, which might indicate protection of the lung from radiation-induced lung injury. Serum tumor necrosis factor alpha and interleukin-1 beta levels, which increased significantly following total body irradiation, were decreased with ozone oxidative preconditioning. Moreover, ozone oxidative preconditioning was able to ameliorate radiation-induced lung injury assessed by histopathological evaluation. In conclusion, ozone oxidative preconditioning, repeated low-dose intraperitoneal administration of ozone, did not exacerbate radiation-induced lung injury, and, on the contrary, it provided protection against radiation-induced lung damage. PMID:23969972

Bakkal, B H; Gultekin, F A; Guven, B; Turkcu, U O; Bektas, S; Can, M



Characterization of N-isopropyl acrylamide/acrylic acid grafted polypropylene nonwoven fabric developed by radiation-induced graft polymerization  

NASA Astrophysics Data System (ADS)

Radiation-induced graft copolymerization of N-isopropylacrylamide (NIPAAm) and acrylic acid (AA) mixture was carried out on polypropylene nonwoven fabric to develop a thermosensitive material and has been found to affect the thermal and physical characteristics of fabric. The grafted fabrics with different monomer ratios were characterized by thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), contact angle and atomic force microscopy (AFM). Results of FTIR clearly indicated that poly(acrylic acid) and poly(N-isopropyl acrylamide) were successfully grafted onto the membrane surface. TGA results showed that the thermal stability of PP fabric increased after grafting of NIPAAm/AA. The crystallinity values from DSC and XRD were found to decrease with increase in degree of grafting because of the addition of grafted chains within the noncrystalline region. The decrease in contact angles of the grafted fabric with an increase of the degree of grafting shows that PNIPAAm/PAA exists as the hydrophilic component. The increase in surface roughness after grafting was observed by AFM.

Kumari, Mamta; Gupta, Bhuvanesh; Ikram, Saiqa



SOD2-mediated Adaptive Responses Induced by Low Dose Ionizing Radiation via TNF Signaling and Amifostine  

PubMed Central

Manganese superoxide dismutase (SOD2)-mediated adaptive processes that protect against radiation-induced micronuclei formation can be induced in cells following a 2 Gy exposure by previously exposing them to either low dose ionizing radiation (10 cGy) or WR1065 (40 µM), the active thiol form of amifostine. While both adaptive processes culminate with elevated levels of SOD2 enzymatic activities, the underlying pathways differ in complexity, with the tumor necrosis factor ? (TNF?) signaling pathway implicated in the low dose radiation-induced response, but not in the thiol-induced pathway. The goal of this study was the characterization of the effects of TNF? receptors1 and 2 (TNFR1, 2) on the adaptive responses induced by low dose irradiation or thiol exposures using micronuclei formation as an endpoint. BFS-1 wild type (WT) cells with functional TNFR1 and 2 were exposed 24 h prior to a 2 Gy dose of ionizing radiation to either 10 cGy or a 40 µM dose of WR1065. BFS2C-SH02 cells defective in TNFR1 and BFS2C-SH22 cells defective in both TNFR1 and 2, generated from BFS2C-SH02 cells by transfection with a murine TNFR2 targeting vector and confirmed to be TNFR2 defective by quantitative PCR, were also exposed under similar conditions for comparison. A 10 cGy dose of radiation induced a significant elevation of SOD2 activity in BFS-1 (P < 0.001) and BFS2C-SH02 (P = 0.005) but not BFS2C-SH22 cells (P = 0.433) as compared to their respective untreated controls. In contrast, WR1065 significantly induced elevations in SOD2 activity in all three cell lines (P = 0.001; P = 0.007; P = 0.020; respectively). A significant reduction in the frequency of radiation-induced micronuclei was observed in each cell line when exposure to a 2 Gy challenge dose of radiation occurred during the period of maximal elevation in SOD2 activity. However, this adaptive effect was completely inhibited if the cells were transfected 24 h prior to low dose radiation or thiol exposure with SOD2 siRNA. Under the conditions tested, TNFR1,2 inhibition negatively impacted the low dose radiation-induced but not the thiol-induced adaptive responses observed to be mediated by elevations in SOD2 activity.

Murley, J.S.; Baker, K.L.; Miller, R.C.; Darga, T.E.; Weichselbaum, R.R.; Grdina, D.J.



Radiation and inhibition of angiogenesis by canstatin synergize to induce HIF-1?-mediated tumor apoptotic switch  

PubMed Central

Tumor radioresponsiveness depends on endothelial cell death, which leads in turn to tumor hypoxia. Radiation-induced hypoxia was recently shown to trigger tumor radioresistance by activating angiogenesis through hypoxia-inducible factor 1–regulated (HIF-1–regulated) cytokines. We show here that combining targeted radioiodide therapy with angiogenic inhibitors, such as canstatin, enhances direct tumor cell apoptosis, thereby overcoming radio-induced HIF-1–dependent tumor survival pathways in vitro and in vivo. We found that following dual therapy, HIF-1? increases the activity of the canstatin-induced ?v?5 signaling tumor apoptotic pathway and concomitantly abrogates mitotic checkpoint and tetraploidy triggered by radiation. Apoptosis in conjunction with mitotic catastrophe leads to lethal tumor damage. We discovered that HIF-1 displays a radiosensitizing activity that is highly dependent on treatment modalities by regulating key apoptotic molecular pathways. Our findings therefore support a crucial role for angiogenesis inhibitors in shifting the fate of radiation-induced HIF-1? activity from hypoxia-induced tumor radioresistance to hypoxia-induced tumor apoptosis. This study provides a basis for developing new biology-based clinically relevant strategies to improve the efficacy of radiation oncology, using HIF-1 as an ally for cancer therapy.

Magnon, Claire; Opolon, Paule; Ricard, Marcel; Connault, Elisabeth; Ardouin, Patrice; Galaup, Ariane; Metivier, Didier; Bidart, Jean-Michel; Germain, Stephane; Perricaudet, Michel; Schlumberger, Martin



Experimental observation of laser-induced radiation heat waves  

SciTech Connect

The propagation of a radiation heat wave through a thin foil of solid gold was investigated experimentally. The wave is driven by the intense thermal radiation in 1--3-mm-diam gold cavities heated by an intense laser pulse (duration 0.8--0.9 ns, wavelength 0.35 {mu}m) to temperatures of more than 200 eV. Evidence of the propagating wave was obtained from the delayed onset of intense thermal emission from the outer side of the foil. The results agree with theoretical predictions for a self-similar ablative heat wave and with numerical simulations.

Sigel, R.; Tsakiris, G.D.; Lavarenne, F.; Massen, J.; Fedosejevs, R.; Meyer-ter-Vehn, J.; Murakami, M.; Eidmann, K.; Witkowski, S. (Max-Planck-Institut fuer Quantenoptik, D-8046 Garching (Federal Republic of Germany)); Nishimura, H.; Kato, Y.; Takabe, H.; Endo, T.; Kondo, K.; Shiraga, H.; Sakabe, S.; Jitsuno, T.; Takagi, M.; Yamanaka, C.; Nakai, S. (Institute of Laser Engineering, Osaka University, Suita, Osaka 565 (Japan))



Amelioration of radiation-induced hematopoietic and gastrointestinal damage by Ex-RAD® in mice  

PubMed Central

The aim of the present study was to assess recovery from hematopoietic and gastrointestinal damage by Ex-RAD®, also known as ON01210.Na (4-carboxystyryl-4-chlorobenzylsulfone, sodium salt), after total body radiation. In our previous study, we reported that Ex-RAD, a small-molecule radioprotectant, enhances survival of mice exposed to gamma radiation, and prevents radiation-induced apoptosis as measured by the inhibition of radiation-induced protein 53 (p53) expression in cultured cells. We have expanded this study to determine best effective dose, dose-reduction factor (DRF), hematological and gastrointestinal protection, and in vivo inhibition of p53 signaling. A total of 500 mg/kg of Ex-RAD administered at 24 h and 15 min before radiation resulted in a DRF of 1.16. Ex-RAD ameliorated radiation-induced hematopoietic damage as monitored by the accelerated recovery of peripheral blood cells, and protection of granulocyte macrophage colony-forming units (GM-CFU) in bone marrow. Western blot analysis on spleen indicated that Ex-RAD treatment inhibited p53 phosphorylation. Ex-RAD treatment reduces terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay (TUNEL)-positive cells in jejunum compared with vehicle-treated mice after radiation injury. Finally, Ex-RAD preserved intestinal crypt cells compared with the vehicle control at 13 and 14 Gy. The results demonstrated that Ex-RAD ameliorates radiation-induced peripheral blood cell depletion, promotes bone marrow recovery, reduces p53 signaling in spleen and protects intestine from radiation injury.

Ghosh, Sanchita P.; Kulkarni, Shilpa; Perkins, Michael W.; Hieber, Kevin; Pessu, Roli L.; Gambles, Kristen; Maniar, Manoj; Kao, Tzu-Cheg; Seed, Thomas M.; Kumar, K. Sree



Rain-Induced Increase in Background Radiation Detected by Radiation Portal Monitors.  

National Technical Information Service (NTIS)

A complete understanding of both the steady state and transient background measured by Radiation Portal Monitors (RPMs) is essential to predictable system performance, as well as maximization of detection sensitivity. To facilitate this understanding, a t...

C. S. Blessinger P. A. Hausladen R. J. Livesay T. F. Guzzardo



Radiation Induced Stress Relaxation in Silicone and Polyurethane Elastomers  

SciTech Connect

Many different materials are used in the National Ignition Facility, NIF, located at Lawrence Livermore National Laboratory, LLNL. Some of these are exposed to significant doses of ionizing radiation. Two elastomers are of special interest because they are used in sealing applications with long expected lifetimes. These are LPU4, a polyurethane formulated at LLNL, and Dow Corning DC93-500, a silicone RTV elastomer. In 2004 a program to determine the impact of ionizing radiation on the stress relaxation and compression set characteristics of these two elastomers was undertaken. Since the materials are used in continuous compression and must reliably seal, the primary test utilized was a stress relaxation test. This test provides insight into the ability of a seal to remain functional in a static seal. The test determines how much residual force remains after a certain period of time under compression. The temperature and absorbed radiation dose can dramatically impact this property. In this study the only independent environmental variable studied is the effect of radiation at ambient temperatures. Two levels of radiation exposure were studied, 1 MRad, and 10 MRad. One of the independent test parameters is the compression deflection during storage and in this test the value used was 25%. The need for a compression retention mechanism ruled out radiation exposure in the compressed direction since the high atomic number materials for that device would block the radiation. Therefore, an annular ring was chosen for the specimen shape. The procedures are, as closely as possible, based on ASTM D 6147-97. Since the data is readily obtained at the end of the stress relaxation test, the samples were also evaluated for compression set. Compression set is the essentially permanent deformation incurred in a seal after the seal is compressed for some period of time and then unloaded. Though this is indicative of potential sealing reliability, it is not as direct an indicator of seal performance as is stress relaxation. Compression set does not yield any useable, quantified information but is an indicator of viscoelastic deformation with time. The needed thickness measurements were obtained both from the unloading curves and direct measurement in general accordance with ASTM D395-03. The radiation source for this testing was the Co60 gamma source located at Lawrence Livermore National Laboratory (LLNL). This source has an exposure vessel approximately 29.2cm (11.5-inch) tall with an inside diameter of 7.44cm (2.93-inch). Because of the geometry limits, cylindrical symmetry and limited volume, a standard stress relaxation test such as ASTM D 6147-97 could not be utilized and a modified test was developed. An additional constraint imposed by the vertical asymmetry of the radiation dose in the exposure chamber was a limited height with reasonably uniform radiation exposure. The specific dimensions and radiation characteristics of the test cell are in Appendix A.

Spellman, G; Gourdin, W; Jensen, W; Pearson, M; Fine, I



Stretching-induced crystallinity and orientation of polylactic acid nanofibers with improved mechanical properties using an electrically charged rotating viscoelastic jet  

Microsoft Academic Search

An electrospinning technique with an additional centrifugal field was employed to prepare polylactic acid (PLA) nanofibers. The results indicated that combining the strong stretching force of the additional centrifugal field and an electrostatic field can align the PLA polymer chains parallel to the nanofiber axis, producing PLA nanofibers with superior crystalline features, molecular orientation and conformation as well as good

Chia-Chun Liao; Cheng-Chien Wang; Chuh-Yung Chen



Comparison measurements of currents induced by radiation and injection  

Microsoft Academic Search

Measurements that show significant differences between currents measured in individual wires of a bundle due to equal current excitations by external radiated fields or by bulk injection are reported. This raises concern whether bulk current injection is a reliable technique for EMC work

John W. Adams; Jose Cruz; Dean Melquist



Biological Defense and Adaptation Induced by Low Dose Radiation  

Microsoft Academic Search

The present paper reviews recent experimental data obtained from studies on stimulation of immune functions and induction of cytogenetic adaptive response by low level radiation. An attempt is made to integrate recent observations in the author's laboratory. Emphasis is given to the effects of single and chronic whole-body irradiation (WBI) with X- or ?-rays. A schematic diagram of the interactions

Shu-Zhang Liu



Radiation induced degradation of dyes—An overview  

Microsoft Academic Search

Synthetic dyes are a major part of our life. Products ranging from clothes to leather accessories to furniture all depend on extensive use of organic dyes. An unfortunate side effect of extensive use of these chemicals is that huge amounts of these potentially carcinogenic compounds enter our water supplies. Various advanced oxidation processes (AOPs) including the use of high-energy radiation

M. A. Rauf; S. Salman Ashraf



Synchrotron radiation induced X-ray fluorescence at LURE  

Microsoft Academic Search

Advantages of X-ray fluorescence with the use of Synchrotron Radiation are emphasized (intensity, polarization, tunability of energy). The experimental set-up and the fast computer system for the data reduction without standards are presented. The results are in good agreement with standard references. Examples of applications are presented: old coins and potteries were studied in archaeological domain; metal alloys were analyzed;

I. Brissaud; J. X. Wang; P. Chevallier



Synchrotron-Radiation Induced X-Ray Emission (SRIXE)  

Microsoft Academic Search

Elemental analysis using emission of characteristic x rays is a well-established scientific method. The success of this analytical method is highly dependent on the properties of the source used to produce the x rays. X-ray tubes have long existed as a principal excitation source, but electron and proton beams have also been employed extensively. The development of the synchrotron radiation

Keith W



Radiation-induced large intracranial vessel occlusive vasculopathy  

Microsoft Academic Search

Two patients who developed large intracranial vessel occlusion after standard radiation therapy for brain tumor are described. This form of vascular occlusion is usually seen in patients who have previously been treated by radiotherapy for intracranial tumor who then develop a relatively acute change in neurologic status. Histology of the lesion mimics accelerated focal arteriosclerosis. The clinical and radiographic manifestations

Michael Brant-Zawadzki; Mark Anderson; Stephen J. DeArmond; Frances K. Conley; Robert W. Jahnke




Microsoft Academic Search

Results of experiments on partial-body irradiation of queen honey bees ; show that irradiating the segments III through V of the abdomen produces the same ; lethal effect as whole-body irradiation, whereas irradiating any other body ; region does not produce a significant amount of radiation deaths during the ; following three weeks. Apparently, irradiation of segments III through V



Treatment of Radiation Induced Hemorrhagic Cystitis With Hyperbaric Oxygen  

Microsoft Academic Search

PurposeHemorrhagic cystitis can occur 6 months to 10 years after pelvic radiation therapy with moderate to severe persistent rates of hematuria as 3% to 5% after radiotherapy for pelvic malignancies. Current treatment modalities for hemorrhagic cystitis include oral and intravenous agents, intravesical therapy and selective embolization of the hypogastric arteries. Hyperbaric oxygen therapy is now a widely accepted treatment option




Mechanisms of radiation-induced conditioned taste aversion learning  

Microsoft Academic Search

The literature on taste aversion learning is reviewed and discussed, with particular emphasis on those studies that have used exposure to ionizing radiation as an unconditioned stimulus to produce a conditioned taste aversion. The primary aim of the review is to attempt to define the mechanisms that lead to the initiation of the taste aversion response following exposure to ionizing

B. M. Rabin; W. A. Hunt



Superior vena cava obstruction caused by radiation induced venous fibrosis  

PubMed Central

Superior vena cava syndrome is most often caused by lung carcinoma. Two cases are described in whom venous obstruction in the superior mediastinum was caused by local vascular fibrosis due to radiotherapy five and seven years earlier. The development of radiation injury to greater vessels is discussed, together with the possibilities for treatment of superior vena cava syndrome.??

Van Putten, J W G; Schlosser, N; Vujaskovic, Z; Leest, A; Groen, H




Microsoft Academic Search

Monomeric formaldehyde is rapidly polymerized by ionizing radiation, ; especially in the liquid state, and gives the polyoxymethylene of high molecular ; weight. The reaction rate itself is large but considerably different in bulk and ; solution systems. There is no linear relation between the polymerization rate ; and monomer concentration. This paper confirms these facts for solution ; polymerization

S. Nakashio; K. Takahashi; M. Kondo



Radiation induced degradation of EPR by IR oxidation profiling  

Microsoft Academic Search

Infrared absorption spectroscopy has been used to investigate the effect of gamma-radiation on ethylene-propylene copolymer loaded with different amount of antioxidant. The oxidation profiles were obtained analyzing slices of the samples by an IR microscope. The IR spectra have shown that the antioxidant content does not affect the shape of the oxidation profiles; their dependence on thickness and dose rate

S. Baccaro; U. Buontempo; P. D'Atanasio



Observation of the full time evolution of the nuclear collective-decay mode in crystalline ⁵⁷FeâOâ excited by synchrotron radiation  

Microsoft Academic Search

The full time evolution of the coherent deexcitation of the 14.4-keV nuclear resonance, excited by synchrotron radiation in a single crystal of the simple antiferromagnet ⁵⁷FeâOâ has been measured. The buildup from zero decay probability at time zero following excitation, increasing to a maximum 2.4 nsec later, has been observed experimentally for the first time. The results are in good

G. Faigel; D. P. Siddons; J. B. Hastings; P. E. Haustein; J. R. Grover; L. E. Berman



Fission fragment damage in crystalline phases possibly formed in solidified radioactive waste  

Microsoft Academic Search

Radiation damage induced by fission fragments has been studied qualitatively, mainly by powder X-ray diffraction, in several crystalline phases which might occur in radioactive waste solidified by ceramic methods. The phases were synthesized by ceramic techniques and contained depleted or enriched uranium. Reactor irradiation induced fission fragment damage.Oxides such as MgO, ?-AI2O3, Fe2O3, ThO2, Y2O3-stabilized ZrO2, and Y2O3 did not

E. R. Vance; K. K. S. Pillay



A Survey of Radiation-Induced Bronchiolitis Obliterans Organizing Pneumonia Syndrome After Breast-Conserving Therapy in Japan  

Microsoft Academic Search

Purpose: We observed a rare and unique occurrence of radiation-induced pulmonary injury outside the tangential field for early breast cancer treatment. The findings appeared to be idiopathic and were called radiation-induced bronchiolitis obliterans organizing pneumonia (BOOP) syndrome. We surveyed major hospitals in Japan to review their findings of radiation-induced BOOP, in particular the clinical and pictorial characteristics of the entity.

Etsuyo Ogo; Ritsuko Komaki; Kiminori Fujimoto; Masafumi Uchida; Toshi Abe; Katsumasa Nakamura; Michihide Mitsumori; Kenji Sekiguchi; Yuko Kaneyasu; Naofumi Hayabuchi



Methylglyoxal-bis(guanylhydrazone), a polyamine analogue, sensitized ?-radiation-induced cell death in HL60 leukemia cells  

Microsoft Academic Search

Methylglyoxal-bis(guanylhydrazone) (MGBG), a polyamine analogue, has been known to inhibit the biosynthesis of polyamines, which are important in cell proliferation. We showed that MGBG treatment significantly affected ?-radiation-induced cell cycle transition (G1\\/G0?S?G2\\/M) and thus ?-radiation-induced cell death. As determined by micronuclei and comet assay, we showed that it sensitized the cytotoxic effect induced by ?-radiation. One of the reasons is

Jin Sik Kim; Jin Lee; Hai Won Chung; Han Choi; Sang Gi Paik; In Gyu Kim



Biocompatibility of crystalline opal nanoparticles  

PubMed Central

Background Silica nanoparticles are being developed as a host of biomedical and biotechnological applications. For this reason, there are more studies about biocompatibility of silica with amorphous and crystalline structure. Except hydrated silica (opal), despite is presents directly and indirectly in humans. Two sizes of crystalline opal nanoparticles were investigated in this work under criteria of toxicology. Methods In particular, cytotoxic and genotoxic effects caused by opal nanoparticles (80 and 120 nm) were evaluated in cultured mouse cells via a set of bioassays, methylthiazolyldiphenyl-tetrazolium-bromide (MTT) and 5-bromo-2?-deoxyuridine (BrdU). Results 3T3-NIH cells were incubated for 24 and 72 h in contact with nanocrystalline opal particles, not presented significant statistically difference in the results of cytotoxicity. Genotoxicity tests of crystalline opal nanoparticles were performed by the BrdU assay on the same cultured cells for 24 h incubation. The reduction of BrdU-incorporated cells indicates that nanocrystalline opal exposure did not caused unrepairable damage DNA. Conclusions There is no relationship between that particles size and MTT reduction, as well as BrdU incorporation, such that the opal particles did not induce cytotoxic effect and genotoxicity in cultured mouse cells.



Radiation induced darkening of the optical elements in the Startracker camera  

SciTech Connect

Optical glass flats that closely simulate the elements used in the Startracker lens designs were exposed to doses of ionizing radiation ranging from 0.44 to 1300 krad. Photometer traces determined the transmittance of the samples as a function of both wavelength and dose for wavelengths in the range 300 to 1200 nm. Cerium stabilized glasses used in the radiation stabilized Startracker system showed only a small amount of darkening for doses up to and exceeding 1 Mrad. Glasses used in the unstabilized Startracker design showed significant darkening to visible and ultra-violet spectra for doses as low as 5 krad. Plots of transmittance versus wavelength for various doses are given for each of the Startracker optical elements. Radiation induced absorption parameters that determine the radiation induced absorption coefficient are tabulated and plotted versus wavelength.

White, R.H.; Wirtenson, G.R.



Simulation of ion beam induced current in radiation detectors and microelectronic devices.  

SciTech Connect

Ionizing radiation is known to cause Single Event Effects (SEE) in a variety of electronic devices. The mechanism that leads to these SEEs is current induced by the radiation in these devices. While this phenomenon is detrimental in ICs, this is the basic mechanism behind the operation of semiconductor radiation detectors. To be able to predict SEEs in ICs and detector responses we need to be able to simulate the radiation induced current as the function of time. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. On the other end, TCAD programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. A simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework.

Vizkelethy, Gyorgy



Radiation-Induced Glioblastoma Multiforme in a Remitted Acute Lymphocytic Leukemia Patient  

PubMed Central

Radiation therapy has been widely applied for cancer treatment. Childhood acute lymphocytic leukemia (ALL), characterized by frequent central nervous system involvement, is a well documented disease for the effect of prophylactic cranio-spinal irradiation. Irradiation, however, acts as an oncogenic factor as a delayed effect and it is rare that glioblastoma multiforme develops during the remission period of ALL. We experienced a pediatric radiation-induced GBM patient which developed during the remission period of ALL, who were primarily treated with chemotherapeutic agents and brain radiation therapy for the prevention of central nervous system (CNS) relapse. Additionally, we reviewed the related literature regarding on the effects of brain irradiation in childhood and on the prognosis of radiation induced GBM.

Joh, Daewon; Lim, Young Jin



Simulation of ion beam induced current in radiation detectors and microelectronic devices.  

SciTech Connect

Ionizing radiation is known to cause Single Event Effects (SEE) in a variety of electronic devices. The mechanism that leads to these SEEs is current induced by the radiation in these devices. While this phenomenon is detrimental in ICs, this is the basic mechanism behind the operation of semiconductor radiation detectors. To be able to predict SEEs in ICs and detector responses we need to be able to simulate the radiation induced current as the function of time. There are analytical models, which work for very simple detector configurations, but fail for anything more complex. On the other end, TCAD programs can simulate this process in microelectronic devices, but these TCAD codes costs hundreds of thousands of dollars and they require huge computing resources. In addition, in certain cases they fail to predict the correct behavior. A simulation model based on the Gunn theorem was developed and used with the COMSOL Multiphysics framework.

Vizkelethy, Gyorgy



353. Retrovirally-Marked Human Bone Marrow Derived Mesenchymal Stem Cells Attenuate Radiation Induced Pneumonitis in a Xenotransplant Model  

Microsoft Academic Search

Thoracic radiation is used to treat patients with malignancies to improve survival and decrease symptoms. Radiation induced lung toxicity limits thoracic radiation doses and volumes and can restrict therapeutic use of radiation. Clinical radiation pneumonitis can be life-threatening, despite aggressive steroid treatment, especially in those patients with pre-existing pulmonary disease.We hypothesize that bone marrow derived mesenchymal stem cells (BMSC) assist

Andrew Hope; Todd E. Meyerrose; Jan A. Nolta



Liquid-crystalline terpyridines.  


5,5"-Disubstitution of the terpyridine core leads to the first inherently liquid-crystalline terpyridines. Mesophases characteristic of bent-core and calamitic systems may be obtained depending on the core structure employed. PMID:18217660

Kozhevnikov, Valery N; Whitwood, Adrian C; Bruce, Duncan W



Liquid Crystalline Polymers.  

National Technical Information Service (NTIS)

This research produced the first quantitative approach to the elucidation of the structure-properties relationship in the field of side chain liquid crystalline polymers via a molecular engineering approach. The elucidation of the mechanisms required for ...

V. Percec



Radiation-induced conductivity of doped silicon in response to photon, proton and neutron irradiation  

Microsoft Academic Search

The opto-electronic performance of semiconductors during reactor operation is restricted by radiation-induced conductivity (RIC) and the synergistic effects of neutrons\\/ions and photons. The RICs of Si due to photons, protons and pulsed neutrons have been evaluated, aiming at radiation correlation. Protons of 17 MeV with an ionizing dose rate of 103 Gy\\/s and\\/or photons (h?=1.3eV) were used to irradiate impurity-doped

N. Kishimoto; H. Amekura; O. A. Plaksin; V. A. Stepanov



Does altered fractionation influence the risk of radiation-induced optic neuropathy?  

Microsoft Academic Search

Purpose: To analyze the parameters that influence the risk of radiation-induced optic neuropathy (RION) after radiotherapy for head-and-neck tumors. Methods and Materials: Between 1964 and 2000, 273 patients with tumors of the nasopharynx, paranasal sinuses, nasal cavity, and hard palate adenoid cystic carcinomas were treated with curative intent and had radiation fields that included the optic nerves and\\/or chiasm. Patients

Niranjan Bhandare; Alan T. Monroe; Christopher G. Morris; M. Tariq Bhatti; William M.. Mendenhall



Radiation-induced degradation of water pollutants—state of the art  

Microsoft Academic Search

The radiation-induced decomposition of biological resistant pollutants in drinking as well as in wastewater is briefly reviewed. First, some important units, definitions etc., radiation sources, as well as dose-depth curves in water as functions of the electron energy and 60Co-?-rays are mentioned. Following is a schematical presentation of water radiolysis and of characteristics of primary free radicals. Then the degradation

Nikola Getoff



Quercetin ameliorates gamma radiation-induced DNA damage and biochemical changes in human peripheral blood lymphocytes  

Microsoft Academic Search

We investigated the radioprotective efficacy of quercetin (QN), a naturally occurring flavonoid against gamma radiation-induced damage in human peripheral blood lymphocytes and plasmid DNA. In plasmid study, QN at different concentrations (3, 6, 12, 24 and 48?M) were pre-incubated with plasmid DNA for 1h followed by exposure of 6Gy radiation. Among all concentrations of QN used, 24?M showed optimum radioprotective

Nagarajan Devipriya; Adluri Ram Sudheer; Marimuthu Srinivasan; Venugopal P. Menon



On the mechanisms of radiation-induced curing of epoxy-fiber composites  

NASA Astrophysics Data System (ADS)

Depending on the monomer molecular structure, the mechanisms of radiation-induced polymerization proceed via either C-centered radical mechanisms or cationic polymerization. While polymerization via C-centered radicals can be impeded by the presence of oxygen and high dose-rate, polymerization through cationic polymerization is inhibited even by the presence of trace amounts of water. Synergy by the combination of radiation and thermal curing can help to achieve various desired properties of polymer-fiber composite materials.

Al-Sheikhly, Mohamad; McLaughlin, William L.



p53Independent ceramide formation in human glioma cells during ?-radiation-induced apoptosis  

Microsoft Academic Search

Although the p53 tumor-suppressor gene product plays a critical role in apoptotic cell death induced by DNA-damaging chemotherapeutic agents, human glioma cells with functional p53 were more resistant to ?-radiation than those with mutant p53. U-87 MG cells with wild-type p53 were resistant to ?-radiation. U87-W E6 cells that lost functional p53, by the expression of type 16 human papillomavirus

S Hara; S Nakashima; T Kiyono; M Sawada; S Yoshimura; T Iwama; Y Banno; J Shinoda; N Sakai



Confocal Imaging of Thermal Lensing Induced by Near-IR Laser Radiation in an Artificial Eye  

Microsoft Academic Search

A custom confocal imaging system was built and used to record a probe beam's spatiotemporal response to a thermal lens induced by a near-IR laser radiation source in a water-filled artificial eye. The IR laser radiation input power levels were varied between 150 and 890 mW at wavelengths of 1110, 1130, 1150 and 1318 nm in order to determine the

Rebecca L. Vincelette; Jeffrey W. Oliver; Benjamin A. Rockwell; Robert J. Thomas; Ashley J. Welch



Radiation induced G 1-block and p53 status in six human cell lines  

Microsoft Academic Search

Considerable attention has recently been focused on the fact that the tumor suppressor protein p53 is involved in the cellular response to radiation. In its wild-type form the protein appears to control a cell cycle checkpoint, preventing entry into S-phase following DNA damage. A number of authors observed a radiation induced G1-block in cells expressing wild-type p53, but not in

F. Zölzer; S. Hillebrandt; C. Streffer



Radiation-induced desulfurization of Arabian crude oil and straight-run diesel  

Microsoft Academic Search

Radiation-induced desulfurization of four types of Arabian crude oils (heavy, medium, light and extra light) and straight-run diesel (SRD) was investigated over the range of 10–200kGy. Results show that gamma radiation processing at absorbed doses up to 200kGy without further treatment is not sufficient for desulfurization. However, the combination of gamma-irradiation with other physical\\/chemical processes (i.e. L\\/L extraction, adsorption and

A. A. Basfar; K. A. Mohamed



Gamma radiation-induced heritable mutations at repetitive DNA loci in out-bred mice  

Microsoft Academic Search

Recent studies have shown that expanded-simple-tandem-repeat (ESTR) DNA loci are efficient genetic markers for detecting radiation-induced germline mutations in mice. Dose responses following irradiation, however, have only been characterized in a small number of inbred mouse strains, and no studies have applied ESTRs to examine potential modifiers of radiation risk, such as adaptive response. We gamma-irradiated groups of male out-bred

C. M. Somers; R. Sharma; J. S. Quinn; D. R. Boreham



Optical Bleaching Effect and Induced Radiation Response in Chelyabinsk Meteorite  

NASA Astrophysics Data System (ADS)

The features of optically stimulated luminescence have been studied in Chelyabinsk LL5 chondrite after X-ray irradiation. The decay parameters of induced lightsum decrease have been evaluated for observed bleaching processes.

Vokhmintsev, A. S.; Weinstein, I. A.; Grokhovsky, V. I.



Radiation effects on regeneration and T-cell-inducing function of the thymus  

SciTech Connect

Radiation effects on regeneration and T-cell-inducing function of the thymus were studied in three sets of experiments. When TXB mice were grafted with 1-week-old thymus which had been previously irradiated at various doses, an exponential decrease was observed in the morphological regeneration of the thymus grafts and in their T-cell-inducing function at doses of 600 R and over, showing about 10% that of the control at 1500 R. When in situ thymus of adult mice was locally irradiated, the radiation effect on T-cell-inducing function was less pronounced as compared with the first experiment; i.e., about 40% of the control at 1797 R. When in situ thymus of 1-day-old newborn mice was locally irradiated, regeneration potential of 1-day-old newborn thymus was highly resistant to radiation exposure and no effect on immunological functions was observed even by local irradiation of 2000 R.

Hirokawa, K.; Sado, T.



Ionizing radiation-induced fragmentation of plasmid DNA Atomic force microscopy and biophysical modeling  

NASA Astrophysics Data System (ADS)

It is widely accepted that DNA double-strand breaks (DSBs) are closely correlated with radiation-induced cell killing and are the most critical lesions related to cellular endpoints like mutagenesis and transformation. High linear energy transfer (LET) radiation produces more severe and complex damage due to the fact that induced DSBs are not randomly distributed but clustered at different levels of DNA organization. In this paper, direct visualization of DSBs induced in a plasmid supercoiled DNA by low- and high-LET radiation is presented. Resulting DNA fragments distributions obtained by use of atomic force microscopy (AFM) are shown. Moreover, a biophysical model of spatially correlated DSBs formation in the framework of the Local Effect Model (LEM) is introduced and its predictions on DNA fragment formation are discussed.

Psonka, K.; Gudowska-Nowak, E.; Brons, S.; Elsässer, Th.; Heiss, M.; Taucher-Scholz, G.