Radiation-resistant camera tube

International Nuclear Information System (INIS)

Kuwahata, Takao; Manabe, Sohei; Makishima, Yasuhiro

1982-01-01

It was a long time ago that Toshiba launched on manufacturing black-and-white radiation-resistant camera tubes employing nonbrowning face-plate glass for ITV cameras used in nuclear power plants. Now in compliance with the increasing demand in nuclear power field, the Company is at grips with the development of radiation-resistant single color-camera tubes incorporating a color-stripe filter for color ITV cameras used under radiation environment. Herein represented are the results of experiments on characteristics of materials for single color-camera tubes and prospects for commercialization of the tubes. (author)

Adriamycin resistance, heat resistance and radiation response in Chinese hamster fibroblasts

International Nuclear Information System (INIS)

Wallner, K.; Li, G.

1985-01-01

Previous investigators have demonstrated synergistic interaction between hyperthermia and radiation or Adriamycin (ADR), using cell lines that are sensitive to heat or ADR alone. The authors investigated the effect of heat, radiation or ADR on Chinese hamster fibroblasts (HA-1), their heat resistant variants and their ADR resistant variants. Heat for ADR resistance did not confer cross resistance to radiation. Cells resistant to heat did show cross resistance to ADR. While cells selected for ADR resistance were not cross resistant to heat, they did not exhibit drug potentiation by hyperthermia, characteristic of ADR sensitive cells. Cytofluorometric measurement showed decreased ADR uptake in both heat and ADR resistant cells. The possibility of cross resistance between heat and ADR should be considered when designing combined modality trials

Radiation resistance of Rhizopus stolonifer

International Nuclear Information System (INIS)

Robbertse, P.J.; Du Toit, T.L.; Van der Merwe, L.J.; Koekemoer, M.L.; Eilers, I.M.I.

1983-01-01

A problem encountered with the irradiation of food is that certain micro-organisms are highly resistant to gamma rays. This includes the fungus, Rhizopus stolonifer, associated with most fruits. The Nuclear Development Corporation of South Africa (NUCOR) has found that a combination of radiation and mild heat treatment reduces the radiation dose necessary to kill 90% of R. stolonifer by approximately half. Treatment at 50 degrees Celsius for 10 minutes or at 55 degrees Celsius for five minutes is sufficient. The article discusses the mechanism of radiation resistance in R. stolonifer and the way in which heating affects this resistance

Compact Radiative Control Structures for Millimeter Astronomy

Science.gov (United States)

Brown, Ari D.; Chuss, David T.; Chervenak, James A.; Henry, Ross M.; Moseley, s. Harvey; Wollack, Edward J.

2010-01-01

We have designed, fabricated, and tested compact radiative control structures, including antireflection coatings and resonant absorbers, for millimeter through submillimeter wave astronomy. The antireflection coatings consist of micromachined single crystal silicon dielectric sub-wavelength honeycombs. The effective dielectric constant of the structures is set by the honeycomb cell geometry. The resonant absorbers consist of pieces of solid single crystal silicon substrate and thin phosphorus implanted regions whose sheet resistance is tailored to maximize absorption by the structure. We present an implantation model that can be used to predict the ion energy and dose required for obtaining a target implant layer sheet resistance. A neutral density filter, a hybrid of a silicon dielectric honeycomb with an implanted region, has also been fabricated with this basic approach. These radiative control structures are scalable and compatible for use large focal plane detector arrays.

Radiation resistance of Candida parapsilosis

International Nuclear Information System (INIS)

Kristensen, H.

1982-01-01

The radiation resistance of 30 strains classified as Candida parapsilosis was examined. The strains originated partly from environments where ionizing radiation was used for research or routine purposes, partly from environments with no known possibility for selection of strains with unusually high radiation resistance. D-6 values between 1.5 and 2.4 Megarads were found when the cells were irradiated in the dried state, a D-6 value being the dose necessary to reduce the initial number of colony-forming units with a factor of 10 6 . The majority of D-6 values were between 1.9 and 2.1 Megarads. D-6 values for the cells irradiated in liquid media were about 2/3 of tose in the dried state. No difference in resistance was revealed depending on the origin of the strains examined. For radiation sterilization of medical products the demonstrated resistance of Candida parapsilosis might be of importance of routine use of minimum doses below 2.5 Megarads were to be accepted. (author)

Radiation-resistant control system

International Nuclear Information System (INIS)

Cable, T.C.; Jones, S.

1995-01-01

REMOTEC has developed a open-quotes radiation resistanceclose quotes control system under a U.S. Department of Energy Small Business Innovative Research (SBIR) contract with assistance from the University of Florida. The SBIR goal was to develop a radiation resistant mobile robot from the ANDROS family of hazardous duty mobile robots that REMOTEC manufactures. See Refs. 1 and 2 for additional SBIR results. The control system, as well as the entire ANDROS robot, was redesigned, where necessary, to withstand radiation doses in excess of 10 6 rad. Those components of the robot that could not be purchased as open-quotes radiation hardenedclose quotes were tested under standard operating conditions for determination of their open-quotes radiation resistance.close quotes The entire ANDROS robot was then assembled with these new components and tested to > 10 6 rad

Development of radiation resistant structural materials utilizing fission research reactors in Japan (Role of research reactors)

International Nuclear Information System (INIS)

Shikama, T.; Tanigawa, H.; Nozawa, T.; Muroga, T.; Aoyama, T.; Kawamura, H.; Ishihara, M.; Ito, C.; Kaneda, S.; Mimura, S.

2009-01-01

Structural materials for next-generation nuclear power systems should have a good radiation resistance, where the expected accumulation dose will largely exceed 10 dpa. Among several candidate materials, materials of five categories, 1. Austenitic steels, including high nickel alloys, 2. Low activation ferritic martensitic steels, 3. ODS steels (austenitic and ferritic), 4. Vanadium based alloys, 5. Silicon carbide composites (SiC/SiCf). All have been most extensively studied in Japan, in collaboration among industries, national institutes such as Japan Atomic Energy Agency (JAEA), National Institute for Fusion Science (NIFS) and National Institute for Materials Science (NIMS), and universities. The high nickel base alloys were studied for their low swelling behaviors mainly by the NIMS and the austenitic steels are studied for their reliable engineering data base and their reliable performance in irradiation environments mainly by the JAEA, mainly for their application in the near-term projects such as the ITER and the Sodium Cooled Fast Reactors. The most extensive studies are now concentrated on the Low Activation Ferritic Marsensitic steels and ODS steels, for their application in a demonstration fusion reactor and prototype sodium cooled fast reactors. Fundamental studies on radiation effects are carried out, mainly utilizing Japan Materials Testing Rector (JMTR) with its flexible irradiation ability, up to a few dpa. For higher dpa irradiation, a fast test reactor, JOYO is utilized up to several 10s dpa. Some international collaborations such as Japan/USA and Japan/France are effective to utilize reactors abroad, such as High Flux Isotope Reactor (HFIR) of Oak Ridge National Laboratory, and sodium cooled high flux fast reactors in France. Silicon carbide based composites are extensively studied by university groups led by Kyoto University and the JAEA. For their performance in heavy irradiation environments, the Japan/USA collaboration plays an important role

Isolation of Radiation-Resistant Bacteria from Mars Analog Antarctic Dry Valleys by Preselection, and the Correlation between Radiation and Desiccation Resistance.

Science.gov (United States)

Musilova, Michaela; Wright, Gary; Ward, John M; Dartnell, Lewis R

2015-12-01

Extreme radiation-resistant microorganisms can survive doses of ionizing radiation far greater than are present in the natural environment. Radiation resistance is believed to be an incidental adaptation to desiccation resistance, as both hazards cause similar cellular damage. Desert soils are, therefore, promising targets to prospect for new radiation-resistant strains. This is the first study to isolate radiation-resistant microbes by using gamma-ray exposure preselection from the extreme cold desert of the Antarctic Dry Valleys (a martian surface analogue). Halomonads, identified by 16S rRNA gene sequencing, were the most numerous survivors of the highest irradiation exposures. They were studied here for the first time for both their desiccation and irradiation survival characteristics. In addition, the association between desiccation and radiation resistance has not been investigated quantitatively before for a broad diversity of microorganisms. Thus, a meta-analysis of scientific literature was conducted to gather a larger data set. A strong correlation was found between desiccation and radiation resistance, indicating that an increase in the desiccation resistance of 5 days corresponds to an increase in the room-temperature irradiation survival of 1 kGy. Irradiation at -79°C (representative of average martian surface temperatures) increases the microbial radiation resistance 9-fold. Consequently, the survival of the cold-, desiccation-, and radiation-resistant organisms isolated here has implications for the potential habitability of dormant or cryopreserved life on Mars. Extremophiles-Halomonas sp.-Antarctica-Mars-Ionizing radiation-Cosmic rays.

Intrinsic radiation resistance in human chondrosarcoma cells

International Nuclear Information System (INIS)

Moussavi-Harami, Farid; Mollano, Anthony; Martin, James A.; Ayoob, Andrew; Domann, Frederick E.; Gitelis, Steven; Buckwalter, Joseph A.

2006-01-01

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

Increasing the radiation resistance of single-crystal silicon epitaxial layers

Directory of Open Access Journals (Sweden)

Kurmashev Sh. D.

2014-12-01

Full Text Available The authors investigate the possibility of increasing the radiation resistance of silicon epitaxial layers by creating radiation defects sinks in the form of dislocation networks of the density of 109—1012 m–2. Such networks are created before the epitaxial layer is applied on the front surface of the silicon substrate by its preliminary oxidation and subsequent etching of the oxide layer. The substrates were silicon wafers KEF-4.5 and KDB-10 with a diameter of about 40 mm, grown by the Czochralski method. Irradiation of the samples was carried out using electron linear accelerator "Electronics" (ЭЛУ-4. Energy of the particles was 2,3—3,0 MeV, radiation dose 1015—1020 m–2, electron beam current 2 mA/m2. It is shown that in structures containing dislocation networks, irradiation results in reduction of the reverse currents by 5—8 times and of the density of defects by 5—10 times, while the mobility of the charge carriers is increased by 1,2 times. Wafer yield for operation under radiation exposure, when the semiconductor structures are formed in the optimal mode, is increased by 7—10% compared to the structures without dislocation networks. The results obtained can be used in manufacturing technology for radiation-resistant integrated circuits (bipolar, CMOS, BiCMOS, etc..

Radiation resistance of microorganisms on unsterilized infusion sets

DEFF Research Database (Denmark)

Christensen, E. Ahrensburg; Kristensen, H.; Hoborn, J.

1991-01-01

Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor in a steriliza......Three different methods were used for detecting and isolating microorganisms with high radiation resistance from the microbial contamination on infusion sets prior to sterilization. By all three methods, microorganisms with a radiation resistance high enough to be a critical factor...

Research of radiation-resistant microbial organisms

Energy Technology Data Exchange (ETDEWEB)

Kim, Dongho; Lim, Sangyong; Joe, Minho; Park, Haejoon; Song, Hyunpa; Im, Seunghun; Kim, Haram; Kim, Whajung; Choi, Jinsu; Park, Jongchun

2012-01-15

Many extremophiles including radiation-resistant bacteria Deinococcus radiodurans have special characteristics such as novel enzymes and physiological active substances different from known biological materials and are being in the spotlight of biotechnology science. In this research, basic technologies for the production of new genetic resources and microbial strains by a series of studies in radiation-resistant microbial organisms were investigated and developed. Mechanisms required for radiation-resistant in Deinococcus radiodurans were partly defined by analyzing the function of dinB, pprI, recG, DRA{sub 0}279, pprM, and two-component signal transduction systems. To apply genetic resource and functional materials from Deinococcus species, omics analysis in response to cadmium, construction of macroscopic biosensor, and characterization of carotenoids and chaperon protein were performed. Additionally, potential use of D. geothermalis in monosaccharide production from non-biodegradable plant materials was evaluated. Novel radiation resistant yeasts and bacteria were isolated and identified from environmental samples to obtain microbial and genomic resources. An optimal radiation mutant breeding method was set up for efficient and rapid isolation of target microbial mutants. Furthermore, an efficient ethanol producing mutant strain with high production yield and productivity was constructed using the breeding method in collaboration with Korea Research Institute of Bioscience and Biotechnology. Three Deinococcal bioindicators for radiation dosage confirmation after radiation sterilization process were developed. These results provide a comprehensive information for novel functional genetic elements, enzymes, and physiological active substances production or application. Eventually, industrial microbial cell factories based on radiation resistant microbial genomes can be developed and the technologies can be diffused to bioindustry continuously by this project.

Research of radiation-resistant microbial organisms

International Nuclear Information System (INIS)

Kim, Dongho; Lim, Sangyong; Joe, Minho; Park, Haejoon; Song, Hyunpa; Im, Seunghun; Kim, Haram; Kim, Whajung; Choi, Jinsu; Park, Jongchun

2012-01-01

Many extremophiles including radiation-resistant bacteria Deinococcus radiodurans have special characteristics such as novel enzymes and physiological active substances different from known biological materials and are being in the spotlight of biotechnology science. In this research, basic technologies for the production of new genetic resources and microbial strains by a series of studies in radiation-resistant microbial organisms were investigated and developed. Mechanisms required for radiation-resistant in Deinococcus radiodurans were partly defined by analyzing the function of dinB, pprI, recG, DRA 0 279, pprM, and two-component signal transduction systems. To apply genetic resource and functional materials from Deinococcus species, omics analysis in response to cadmium, construction of macroscopic biosensor, and characterization of carotenoids and chaperon protein were performed. Additionally, potential use of D. geothermalis in monosaccharide production from non-biodegradable plant materials was evaluated. Novel radiation resistant yeasts and bacteria were isolated and identified from environmental samples to obtain microbial and genomic resources. An optimal radiation mutant breeding method was set up for efficient and rapid isolation of target microbial mutants. Furthermore, an efficient ethanol producing mutant strain with high production yield and productivity was constructed using the breeding method in collaboration with Korea Research Institute of Bioscience and Biotechnology. Three Deinococcal bioindicators for radiation dosage confirmation after radiation sterilization process were developed. These results provide a comprehensive information for novel functional genetic elements, enzymes, and physiological active substances production or application. Eventually, industrial microbial cell factories based on radiation resistant microbial genomes can be developed and the technologies can be diffused to bioindustry continuously by this project

Effect of radiation resistance additives for insulation materials

International Nuclear Information System (INIS)

Yamamoto, Yasuaki; Yagyu, Hideki; Seguchi, Tadao.

1988-01-01

For the electric wires and cables used in radiation environment such as nuclear power stations and fuel reprocessing facilities, the properties of excellent radiation resistance are required. For these insulators and sheath materials, ethylene propylene rubber, polyethylene and other polymers have been used, but it cannot be said that they always have good radiation resistance. However, it has been well known that radiation resistance can be improved with small amount of additives, and heat resistance and burning retarding property as well as radiation resistance are given to the insulators of wires and cables for nuclear facilities by mixing various additives. In this research, the measuring method for quantitatively determining the effect of Anti-rad (radiation resistant additive) was examined. Through the measurement of gel fraction, radical formation and decomposed gas generation, the effect of Anti-rad protecting polymers from radiation deterioration was examined from the viewpoint of chemical reaction. The experimental method and the results are reported. The radiation energy for cutting C-H coupling is polymers is dispersed by Anti-rad, and the probability of cutting is lowered. Anti-rad catches and extinguishes radicals that start oxidation reaction. (K.I.)

Radiation resistant lining material

International Nuclear Information System (INIS)

Ouchi, Koki; Okagawa, Seigo; Tamaki, Hidehiro.

1990-01-01

Rigidity, viscoelasticity, flexibility, radiation resistance, leaching resistance, rust-proofness, endurance, etc. are required for the lining materials to wall surfaces and floor surfaces of facilities used under the effect of radiation rays and for the inner surface protection of vessels for radioactive wastes. The present invention provides radiation resistant lining material capable of satisfying such various requirements in a well-balanced manner. That is, the material contains (A) 100 parts by weight of rapidly curing cement, (B) 50 to 300 % by weight of aggregate, and (C) 80 to 120 parts by weight of polymer emulsion. As the specific example, the ingredient (A) is commercially available under the trade name of Jet Cement. The aggregate of the ingredient (B) has preferably from about 0.6 to 0.2 mm of size and is made of material, preferably, silicon or iron grains. As the ingredient (C), acrylic resin emulsion is preferred. As a result of example, these ingredient constitutions can satisfy each of the required performance described above. (I.S.)

Radiation resistant polymers and coatings for nuclear fuel reprocessing plants

International Nuclear Information System (INIS)

Kamachi Mudali, U.; Mallika, C.; Lawrence, Falix

2014-01-01

Polymer based materials are extensively used in the nuclear industry for the reprocessing of spent fuels in highly radioactive and corrosive environment. Hence, these polymer materials are susceptible to damage by ionizing radiation, resulting in the degradation in properties. Polymers containing aromatic molecules generally possess higher resistance to radiation degradation than the aliphatic polymers. For improving the radiation resistance of polymers various methods are reported in the literature. Among the aromatic polymers, polyetheretherketone (PEEK) has the radiation tolerance up to 10 Mega Grey (MGy). To explore the possibility of enhancing the radiation resistance of PEEK, a study was initiated to develop PEEK - ceramic composites and evaluate the effect of radiation on the properties of the composites. PEEK and PEEK - alumina (micron size) composites were irradiated in a gamma chamber using 60 Co source and the degradation in mechanical, structural, electrical and thermal properties, gel fraction, coefficient of friction and morphology were investigated. The degradation in the mechanical properties owing to radiation could be reduced by adding alumina filler to PEEK. Nano alumina filler was observed to be more effective in suppressing the damage caused by radiation on the polymer, when compared to micron alumina filler. For the protection of aluminium components in the manipulators and the rotors and stators of the motors of the centrifugal extractors employed in the plant from the attack by nitric acid vapour, PEEK coating based on liquid dispersion was developed, which has resistance to radiation, chemicals and wear. The effect of radiation and chemical vapour on the properties of the PEEK coating was estimated. The performance of the coating in the plant was evaluated and the coating was found to give adequate protection to the motors of centrifugal extractors against corrosion. (author)

Electrical resistance behavior with gamma radiation dose in bulk carbon nanostrutured samples

International Nuclear Information System (INIS)

Lage, J.; Leyva, A.; Pinnera, I.; Desdin, L. F.; Abreu, Y.; Cruz, C. M.; Leyva, D.; Toledo, C.

2013-01-01

The aim of this paper is to study the effects of 60 Co gamma radiation on the electrical resistance and V-I characteristic of bulk carbon nano structured samples obtained by electric arc discharge in water method. Images of pristine samples obtained with scanning electron, and the results in graphical form of the electrical characterization of irradiated samples are presented in the text. It was observed that the electrical resistance vs. dose behavior shows an initial increment reaching the maximum at approximately 135 kGy, followed by a drop of the resistance values. These behaviors are associated with the progressive generation of radiation induced defects in the sample, whose number increases to reach saturation at 135 kGy. From this dose, defects could lead to cross-links between different nano structures present in the sample conducting to a gradually drop in electrical resistance. The measured V-I curves show that, increasing exposure to the 60 Co gamma radiation, the electrical properties of the studied samples transit from a semiconductor towards a predominantly metallic behavior. These results were compared with those obtained for a sample of graphite powder irradiated under the same conditions. (Author)

Resistive Memory Devices for Radiation Resistant Non-Volatile Memory

Data.gov (United States)

National Aeronautics and Space Administration — Ionizing radiation in space can damage electronic equipment, corrupting data and even disabling computers. Radiation resistant (rad hard) strategies must be employed...

Isolation of radiation-resistant bacteria without exposure to irradiation

International Nuclear Information System (INIS)

Sanders, S.W.; Maxcy, R.B.

1979-01-01

Resistance to desiccation was utilized in the selection of highly radiation-resistant asporogenous bacteria from nonirradiated sources. A bacterial suspension in phosphate buffer was dried in a thin film at 25 0 C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the number of radiation-sensitive bacteria. Further selection for radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, therby avoiding the toxic effect of irradiated media. The similarity of radiation resistance and identifying characteristics in irradiated and non-irradiated isolates should allay some concerns that highly radiation-resistance bacteria have been permanently altered by radiation selection

Design of online testing system of material radiation resistance

International Nuclear Information System (INIS)

Wan Junsheng; He Shengping; Gao Xinjun

2014-01-01

The capability of radiation resistance is important for some material used in some specifically engineering fields. It is the same principal applied in all existing test system that compares the performance parameter after radiation to evaluate material radiation resistance. A kind of new technique on test system of material radiation resistance is put forward in this paper. Experimentation shows that the online test system for material radiation resistance works well and has an extending application outlook. (authors)

Research progress and application prospect of radiation-resistant prokaryotic microbe

International Nuclear Information System (INIS)

Wang Wei; Zhu Jing; Zhang Zhidong; Tang Qiyong; Chen Ming

2013-01-01

Radiation-resistant microbe is becoming the research hotspot because of its special life phenomenon and physiological mechanism. Radiation-resistant bacteria are one kind of the most studied radiation-resistant microbe. This article summarized some aspects of the research on radiation-resistant bacteria, including the radiation resistant bacteria resources, and discussed its potential application prospects in the environmental engineering, biotechnology, human health, military and space et al. (authors)

Effect that radiation exerts to insulation breakdown of heat resistant polymer materials

International Nuclear Information System (INIS)

Fujita, Shigetaka; Baba, Makoto; Noto, Fumitoshi; Ruike, Mitsuo.

1990-01-01

Artificial satellites are always exposed to cosmic rays which contain the radiations which do not reach the ground, therefore, the radiation resistance of the polymer insulators for cables and others used in such environment becomes a problem. Also the polymer insulator materials used for nuclear facilities require excellent radiation resistance. It is important to examine the effect that radiation exerts to electric insulation characteristics from the viewpoint of material development. In this paper, the insulation breakdown characteristics of heat resistant polymer films and the mini-cables made for trial of heat resistant polymer materials in the case without irradiation and in the case of gamma ray irradiation, and the results of the structural analysis are reported. The specimens tested, the experimental method and the results are described. The insulation breakdown strength of PFA and FEP films lowered from 0.15-0.2 MGy, but that of PEEK film did not change up to 5 MGy. It was found that fluorine group resins were apt to deteriorate by oxidation as dose increased. (K.I.)

Utilization of SRNL-developed radiation-resistant polymer in high radiation environments

Energy Technology Data Exchange (ETDEWEB)

Skibo, A. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-09-27

The radiation-resistant polymer developed by the Savannah River National Laboratory is adaptable for multiple applications to enhance polymer endurance and effectiveness in radiation environments. SRNL offers to collaborate with TEPCO in evaluation, testing, and utilization of SRNL’s radiation-resistant polymer in the D&D of the Fukushima Daiichi NPS. Refinement of the scope and associated costs will be conducted in consultation with TECPO.

Radiation resistant organic composites for superconducting fusion magnets

International Nuclear Information System (INIS)

Nishijima, S.; Okada, T.

1993-01-01

Organic composite materials (usually reinforced by glas fibers: GFRP) are to be used in fusion superconducting magnets as insulating and/or structural materials. The fusion superconducting magnets are operated under radiation environments and hence the radiation induced degradation of magnet components is ought to be estimated. Among the components the organic composite materials were evaluated to be the most radiation sensitive. Consequently the development of radiation resistant organic composite materials is thought one of the 'key' technologies for fusion superconducting magnets. The mechanism of radiation-induced degradation was studied and the degradation of interlaminar shear strength (ILSS) was found to be the intrinsic phenomenon which controlled the overall degradation of organic composite materials. The degradation of ILSS was studied changing matrix resin, reinforcement and type of fabrics. The possible combination of the organic composites for the fusion superconducting magnet will be discussed. (orig.)

Final Report for Radiation Resistant Magnets II

International Nuclear Information System (INIS)

A. F. Zeller

2005-01-01

Report on techniques for the fabrication of radiation resistant magnets for the RIA Fragment Separator. The development of magnet designs capable of reasonable life times in high-radiation environments and having reasonable performance is of paramount importance for RIA as well as other high-intensity projects under consideration, such as the Neutrino Factory and FAIR project at GSI. Several approaches were evaluated for radiation resistant superconducting magnets. One approach was to simply use a more radiation resistant epoxy for the coil fabrication. Another approach for cryostable magnets, like the S800 Spectrograph dipole, is the use of all-inorganic materials. The final approach was the development of radiation resistant Cable-In-Conduit-Conductor (CICC) like that used in fusion magnets; though these are not radiation resistant because an organic insulator is used. Simulations have shown that the nuclear radiation heating of the first quadrupoles in the RIA Fragment Separator will be so large that cold mass minimization will be necessary with the magnet iron being at room temperature. Three different types of conductor for radiation resistant superconducting magnets have been built and successfully tested. The cyanate ester potted coils will work nicely for magnets where the lifetime dose is a factor of 20 less than the end of life of the superconductor and the rate of energy deposition is below the heat-removal limit of the coil. The all-inorganic cryostable coil and the metal oxide insulated CICC will provide conductor that will work up to the life of the superconductor and have the ability to remove large quantities of nuclear heating. Obviously, more work needs to be done on the CICC to increase the current density and to develop different insulations; and on the cyanate esters to increase the heat transfer

Development of flame retardant, radiation resistant insulating materials

Energy Technology Data Exchange (ETDEWEB)

Hagiwara, M.

1984-01-01

On the cables used for nuclear power stations, in particular those ranked as IE class, flame retardation test, simulated LOCA environment test, radiation resistance test and so on are imposed. The results of the evaluation of performance by these tests largely depend on the insulating materials mainly made of polymers. Ethylene propylene copolymer rubber has been widely used as cable insulator because of its electrical characteristics, workability, economy and relatively good radiation resistance, but it is combustible, therefore, in the practical use, it is necessary to make it fire resistant. The author et al. have advanced the research on the molecular design of new fire retarding materials, and successfully developed acenaphthylene bromide condensate, which is not only fire resistant but also effective for improving radiation resistance. The condition of flame retardant, radiation resistant auxiliary agents is explained, and there are additive type and reaction type in fire retarding materials. The synthesis of acenaphthylene bromide condensate and its effect of giving flame retardant and radiation resistant properties are reported. The characteristics of the cables insulated with the flame retardant ethylene propylene rubber containing acenaphthylene bromide condensate were tested, and the results are shown. (Kako, I.).

Structural basis of protein oxidation resistance: a lysozyme study.

Directory of Open Access Journals (Sweden)

Marion Girod

Full Text Available Accumulation of oxidative damage in proteins correlates with aging since it can cause irreversible and progressive degeneration of almost all cellular functions. Apparently, native protein structures have evolved intrinsic resistance to oxidation since perfectly folded proteins are, by large most robust. Here we explore the structural basis of protein resistance to radiation-induced oxidation using chicken egg white lysozyme in the native and misfolded form. We study the differential resistance to oxidative damage of six different parts of native and misfolded lysozyme by a targeted tandem/mass spectrometry approach of its tryptic fragments. The decay of the amount of each lysozyme fragment with increasing radiation dose is found to be a two steps process, characterized by a double exponential evolution of their amounts: the first one can be largely attributed to oxidation of specific amino acids, while the second one corresponds to further degradation of the protein. By correlating these results to the structural parameters computed from molecular dynamics (MD simulations, we find the protein parts with increased root-mean-square deviation (RMSD to be more susceptible to modifications. In addition, involvement of amino acid side-chains in hydrogen bonds has a protective effect against oxidation Increased exposure to solvent of individual amino acid side chains correlates with high susceptibility to oxidative and other modifications like side chain fragmentation. Generally, while none of the structural parameters alone can account for the fate of peptides during radiation, together they provide an insight into the relationship between protein structure and susceptibility to oxidation.

Radiation resistance of ethylene-styrene copolymers

International Nuclear Information System (INIS)

Matsumoto, Kaoru; Ikeda, Masaaki; Ohki, Yoshimichi; Kusama, Yasuo; Harashige, Masahiro; Yazaki, Fumihiko.

1988-01-01

In this paper, the radiation resistance of ethylene-styrene copolymer, a polymeric resin developed newly by the authors, is reported. Resin examined were five kinds of ethylene-styrene copolymers: three random and two graft copolymers with different styrene contents. Low-density polyethylene was used as a reference. The samples were irradiated by 60 Co γ-rays to total absorbed doses up to 10 MGy. The mechanical properties of the smaples were examined. Infrared spectroscopy, differential scanning calorimetry and X-ray scattering techniques were used to examine the morphology of the samples. The random copolymers are soft and easy to extend, because benzene rings which exisist highly at random hinder the crystallization. As for the radiation resistance, they are highly resistant to γ-rays in the aspects of carbonyl group formation, gel formation, and elongation. Further, they show even better radiation resistance when proper additives were compounded in. The graft copolymers are hard to extend, because they consist of segregated polystyrene and polyethylene regions which are connected with each other. The tensile strength of irradiated graft copolymers does not decrease below that of unirradiated copolymers, up to a total dose of 10 MGy. As a consequence, it can be said that ethylene-styrene copolymers have good radiation resistance owing to the so-called 'sponge' effect of benzene rings. (author)

Sustainably Sourced, Thermally Resistant, Radiation Hard Biopolymer

Science.gov (United States)

Pugel, Diane

2011-01-01

This material represents a breakthrough in the production, manufacturing, and application of thermal protection system (TPS) materials and radiation shielding, as this represents the first effort to develop a non-metallic, non-ceramic, biomaterial-based, sustainable TPS with the capability to also act as radiation shielding. Until now, the standing philosophy for radiation shielding involved carrying the shielding at liftoff or utilizing onboard water sources. This shielding material could be grown onboard and applied as needed prior to different radiation landscapes (commonly seen during missions involving gravitational assists). The material is a bioplastic material. Bioplastics are any combination of a biopolymer and a plasticizer. In this case, the biopolymer is a starch-based material and a commonly accessible plasticizer. Starch molecules are composed of two major polymers: amylase and amylopectin. The biopolymer phenolic compounds are common to the ablative thermal protection system family of materials. With similar constituents come similar chemical ablation processes, with the potential to have comparable, if not better, ablation characteristics. It can also be used as a flame-resistant barrier for commercial applications in buildings, homes, cars, and heater firewall material. The biopolymer is observed to undergo chemical transformations (oxidative and structural degradation) at radiation doses that are 1,000 times the maximum dose of an unmanned mission (10-25 Mrad), indicating that it would be a viable candidate for robust radiation shielding. As a comparison, the total integrated radiation dose for a three-year manned mission to Mars is 0.1 krad, far below the radiation limit at which starch molecules degrade. For electron radiation, the biopolymer starches show minimal deterioration when exposed to energies greater than 180 keV. This flame-resistant, thermal-insulating material is non-hazardous and may be sustainably sourced. It poses no hazardous

Radiation-resistant micro-organisms isolated from textiles

International Nuclear Information System (INIS)

Kristensen, H.; Christensen, E.A.

1981-01-01

Towels from private homes and public offices and underwear contaminated by being used by employees at a public health laboratory were examined for occurrence of radiation-resistant bacteria and fungi. Three different methods were used for isolation of the most resistant organisms, one with multiplication of the microbial population prior to an irradiation used for selection, and two witout this multiplication and with the organisms placed on membrane filters or in situ on the textiles, respectively. A total of 44 different strains were isolated. Differences in the three methods used for selection of the most radiation-resistant microorganisms were not reflected in the results. 16 pigmentproducing Gram-positive cocci, tentatively classified as Micrococcus radiodurans, were the most radiation-resistant and were isolated in about half of the examinations. Other Gram-positive cocci, nonspore forming rods, some Nocardia and Candida parapsilosis strains and two Bacillus strains constituted the rest of the collection. With few exceptions dose-response curves for the strains were upward convex. D-6 values determined to be between 1.5 megarad for the most radiation sensitive, a Candida, and 5.7 megarad for the most resistant, tentatively classified as M. radiodurans. The D-6 values for the Bacillus strains were in both cases 1.8 megarad, consistent with a D-value of 0.3 megarad. The same resistance is reported to be the maximum resistance for B. pumilus, strain E601, commonly used as reference strain in the literature on radiation sterilization of medical devices and supplies. (author)

Radiation-resistant micro-organisms isolated from textiles

Energy Technology Data Exchange (ETDEWEB)

Kristensen, H; Christensen, E A [Statens Seruminstitut, Copenhagen (Denmark)

1981-01-01

Towels from private homes and public offices and underwear contaminated by being used by employees at a public health laboratory were examined for occurrence of radiation-resistant bacteria and fungi. Three different methods were used for isolation of the most resistant organisms, one with multiplication of the microbial population prior to an irradiation used for selection, and two witout this multiplication and with the organisms placed on membrane filters or in situ on the textiles, respectively. A total of 44 different strains were isolated. Differences in the three methods used for selection of the most radiation-resistant microorganisms were not reflected in the results. 16 pigmentproducing Gram-positive cocci, tentatively classified as Micrococcus radiodurans, were the most radiation-resistant and were isolated in about half of the examinations. Other Gram-positive cocci, nonspore forming rods, some Nocardia and Candida parapsilosis strains and two Bacillus strains constituted the rest of the collection. With few exceptions dose-response curves for the strains were upward convex. D-6 values determined to be between 1.5 megarad for the most radiation sensitive, a Candida, and 5.7 megarad for the most resistant, tentatively classified as M. radiodurans. The D-6 values for the Bacillus strains were in both cases 1.8 megarad, consistent with a D-value of 0.3 megarad. The same resistance is reported to be the maximum resistance for B. pumilus, strain E601, commonly used as reference strain in the literature on radiation sterilization of medical devices and supplies.

Development of radiation-resisting high molecular-weight materials

International Nuclear Information System (INIS)

Nakagawa, Tsutomu

1976-01-01

The excellent radiation-resisting polyvinyl chloride developed at the opportunity of the research on the relationships between the protection of living body and the polymer-technological protection from radiation is reviewed. The report is divided into four main parts, namely 1) the change in the molecular arrangement of market-available, high molecular-weight materials by gamma-ray irradiation, 2) the protection of high molecular-weight materials from radiation, 3) the relationships between the biological radiation-protective substances and the change to radiation-resisting property of synthesized high molecular-weight substances, and 4) the development of the radiation-resisting high molecular-weight materials as metal-collecting agents. Attention is paid to the polyvinyl chloride having N-methyl-dithio-carbamate radical (PMD), synthesized by the author et. al., that has excellent radiation-resisting property. PMD has some possibility to form thiol- and amino-radicals necessary to protect living things from radiation. It is believed that the protection effects of N-methyl-dithio-carbamate radical are caused by the relatively stable S radical produced by the energy transfer. PMD film is suitable for the irradiation of foods, because it hardly changes the permeability of oxygen and carbon dioxide. PMD produces mercaptide or chelate. A new metal-collecting agent (PSDC) having reactivity with the metallic ions with radiation-resisting property was developed, which is derived from polyvinyl chloride and sodium N-methyl-N-carboxy-methyl-dithio-carbamate. (Iwakiri, K.)

Radiation resistant characteristics of optical fibers

International Nuclear Information System (INIS)

Nakasuji, Masaaki; Tanaka, Gotaro; Watanabe, Minoru; Kyodo, Tomohisa; Mukunashi, Hiroaki

1983-01-01

It is required to develop the optical fibers with good radiation resistivity because the fibers cause the increase of transmission loss due to glass colouring when they are used under the presence of radiation such as γ-ray. Generally, it is known that SI (step index) fibers are more resistive to radiation than GI (graded index) fibers. However, since a wide band can not be obtained with SI fibers, the development of radiation resistive GI optical fibers is desirable. In this report, the production for trial of the GI fibers of fluorine-doped silica core, the examination of radiation effect on their optical transmission loss by exposing them to γ-ray, thermal and fast neutron beams and also of mechanical strength are described. The GI fibers of fluorine-doped silica core show better radiation resistivity than Ge-doped ones. The B- and F-doped GI fibers show small increase of loss due to γ-ray, but large increase of loss due to thermal neutron beam. This is supposed to be caused by the far greater neutron absorption cross-section of boron than that of other elements. Significant increase of loss was not recognized when 14 MeV fast neutrons (8.6 x 10 4 n/cm 2 .s) were applied by 1.8 x 10 9 n/cm 2 . It was found that ETFE-covered fiber cores generated fluorine-containing gas due to γ irradiation, and the strength was remarkably lowered, but the lowering of strength can be prevented by adding titanium-white to the covering material. (Wakatsuki, Y.)

Effect of radiation decontamination on drug-resistant bacteria

International Nuclear Information System (INIS)

Ito, Hitoshi

2006-01-01

More than 80% of food poisoning bacteria such as Salmonella are reported as antibiotic-resistant to at least one type antibiotic, and more than 50% as resistant to two or more. For the decontamination of food poisoning bacteria in foods, radiation resistibility on drug-resistant bacteria were investigated compared with drug-sensitive bacteria. Possibility on induction of drug-resistant mutation by radiation treatment was also investigated. For these studies, type strains of Escherichia coli S2, Salmonella enteritidis YK-2 and Staphylococcus aureus H12 were used to induce drug-resistant strains with penicillin G. From the study of radiation sensitivity on the drug-resistant strain induced from E. coli S2, D 10 value was obtained to be 0.20 kGy compared with 0.25 kGy at parent strain. On S. enteritidis YK-2, D 10 value was obtained to be 0.14 kGy at drug-resistant strain compared with 0.16 kGy at parent strain. D 10 value was also obtained to be 0.15 kGy at drug-resistant strain compared with 0.21 kGy at parent strain of St. aureus H12. Many isolates of E. coli 157:H7 or other type of E. coli from meats such as beef were resistant to penicillin G, and looked to be no relationship on radiation resistivities between drug-resistant strains and sensitive strains. On the study of radiation sensitivity on E. coli S2 at plate agars containing antibiotics, higher survival fractions were obtained at higher doses compared with normal plate agar. The reason of higher survival fractions at higher doses on plate agar containing antibiotics should be recovery of high rate of injured cells by the relay of cell division, and drug-resistant strains by mutation are hardly induced by irradiation. (author)

Extreme Ionizing-Radiation-Resistant Bacterium

Science.gov (United States)

Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.; Schwendner, Petra

2013-01-01

There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing micro-organisms. Eradi cation techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation-based sterilization processes. Due to their resistance to a variety of perturbations, the nonspore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-sporeforming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/m2), and desiccation (years). These resistive phenotypes of Deinococcus enhance the

NEW RADIATION RESISTANT GREASES

Energy Technology Data Exchange (ETDEWEB)

DasGupta, Sharda; Slobodian, J. T.

1962-11-20

New radiation resistant greases were prepared from commercially available greases by carrying out radioinduced reactions with styrene. The radiation tolerances of the products were 250-1000 fold more than the starting materials and any product of similar properties now available. The various properties of the new products initially and after exposure to large radiation doses were in no case inferior to the original greases and in some respects improvements were observed. Radiation tolerance of commercial greases could be enhanced by the addition of polystyrene to form a physical mixture rather than copolymers. The reaction mechanisms involved at all stages were studied using infrared spectroscopic techniques. (P.C.H.)

Radiation-resistant photostructure for Schottky diode based on Cr/In2Hg3Te6

Directory of Open Access Journals (Sweden)

Ashcheulov A. A.

2016-05-01

Full Text Available Ge, Si, InGaAs, GaInAsP photodiodes are used as optical radiation receivers and function in a spectral range of transparency of quartz fiberglass. For the optical systems operated in the increased radioactivity the photodetectors' application on In2Hg3Te6 crystal base characterized by a photosensitivity in the spectral range of 0,5-1,6 mm and also by increased radiation resistance to alpha, beta and gamma radiation is most acceptable. Schottky photodiode structure was designed on the base of this semiconductor formed by a modified floating zone recrystallization technique where the sedimentation effect was leveled. It consists of n-In2Hg3Te6 substrate and deposited by cathode sputtering Cr barrier layer of thickness within a range 10-11 nm choice of Cr is determined by its optimal optical, electric and adhesive features in high quality radiation-resistant photodiode structures manufacturing. Indium and nichrome are used as ohmic contacts. The barrier structures have the contact area of 1,13 mm2 with photo response of 0,6-1,6 mm at the maximal sensitivity 0,43 A/W on the wavelength l,55 mm. Reverse dark current of these structures do not exceed 4 mA at the bias of 1 V (T=295 K, and the potential barrier height is equal to 0,41 eV. The tests of radiation resistance of these structures demonstrated their ability to function at doses of 2⋅108 rem without evident parameters changes. This allows using them in practical aims in the conditions of high radiation.

Trial manufacture of flame retardant and radiation resistant cables

Energy Technology Data Exchange (ETDEWEB)

Oshima, Yunosuke; Hagiwara, Miyuki (Japan Atomic Energy Research Inst., Takasaki, Gunma. Takasaki Radiation Chemistry Research Establishment); Oda, Eisuke

1983-04-01

High radiation resistance as well as incombustibility is required for the wires and cables used for nuclear facilities such as nuclear power stations. In order to give such performance to general purpose insulation materials such as ethylene-propylene copolymerized rubber, acenaphthylene bromide condensation product was developed anew. Moreover, by the use of this agent, the new flame retardant and radiation resistant cables were manufactured for trial, which are not different from ordinary plastic rubber cables in the handling such as flexibility, and withstand the radiation nearly up to 1000 Mrad. The requirement for the agent giving flame retardant and radiation resistant properties is explained. The synthesis of acenaphthylene bromide and its condensation product and the effect of giving flame retardant and radiation resistant properties are described. The test resultd of the prevention of spread of flame, the endurance in LOCA-simulating environment, and radiation resistance for the cables manufactured for trial are reported. It was confirmed that the cables of this type are suitable to the use in which the maintenance of mechanical properties after radiation exposure is required.

Radiation resistance of organic azo dyes in aqueous solutions

International Nuclear Information System (INIS)

Khabarov, V.N.; Kozlov, L.L.

1987-01-01

The resistance to the action of the ionizing radiation of aqueous and aqueous-alcoholic solutions of organic mono- and diazo dyes was studied. The radiation chemical yield of decolorization of the dye, determined from the kinetic decolorization curves served as a quantitative criterion of the radiation resistance. The influence of pH, addition of ethanol, hydroquinone, thiourea, glucose and oxygen on the radiation resistance of the azo dyes was studied. An attempt was made to relate the efficiency of radiation decolorization to the chemical nature of the dye

Radiation resistivity of pure silica core image guides for industrial fiberscopes

International Nuclear Information System (INIS)

Okamoto, Shinichi; Ohnishi, Tokuhiro; Kanazawa, Tamotsu; Tsuji, Yukio; Hayami, Hiroyuki; Ishitani, Tadayoshi; Akutsu, Takeji; Suzuki, Koichi.

1991-01-01

Industrial fiberscopes incorporating pure silica core image guides have been extensively used for remote visual inspection in radiation fields including nuclear power plants, owing to their superior radiation resistivity. The authors have been intensively conducting R and D on improving radiation resistivity of pure silica core image guides. This paper reports the results of experiments to compare the effects of core materials on radiation resistivity and to investigate the dependence of radiation resistivity on total dose, does rate, and support pipe material. The results confirmed the superior radiation resistivity of the core material containing fluorine at any irradiation condition and indicated the existence of a critical dose rate at which radiation-induced deterioration was stabilized. No difference in radiation resistivity attributable to support layer material was observed. (author)

Radiation resistant modified polypropylene; Polipropylen modyfikowany odporny radiacyjnie

Energy Technology Data Exchange (ETDEWEB)

Bojarski, J; Zimek, Z [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

1997-10-01

Radiation technology for production of radiation resistant polypropylene for medical use has been presented. The method consists in radiation induced copolymerization of polypropylene with ethylene and addition of small amount of copolymer of polyethylene and vinyl acetate. The material of proposed composition has a very good mechanical properties and elevated radiation resistivity decided on possibility of radiosterilization of products made of this material and designed for medical use. 3 figs, 3 tabs.

Radiation-resistant plastic insulators

International Nuclear Information System (INIS)

Sturm, B.J.; Parkinson, W.W.

1975-01-01

A high molecular weight organic composition useful as an electric insulator in radiation fields is provided and comprises normally a solid polymer of an organic compound having a specific resistance greater than 10 19 ohm-cm and containing phenyl groups and 1 to 7.5 weight percent of a high molecular weight organic phosphite. In one embodiment the composition comprises normally solid polystyrene having 7.5 weight percent tris-β-chloroethyl phosphite as an additive; the composition exhibited an increase in the post-irradiation resistivity of over an order of magnitude over the post-irradiation resistivity of pure polystyrene. (Patent Office Record)

Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Energy Technology Data Exchange (ETDEWEB)

Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min; Lapidus, Alla; Copeland, Alex; Kim, Edwin; Land, Miriam; Mavrommatis, Konstantinos; Pitluck, Samuel; Richardson, Paul M.; Detter, Chris; Brettin, Thomas; Saunders, Elizabeth; Lai, Barry; Ravel, Bruce; Kemner, Kenneth M.; Wolf, Yuri I.; Sorokin, Alexander; Gerasimova, Anna V.; Gelfand, Mikhail S.; Fredrickson, James K.; Koonin, Eugene V.; Daly, Michael J.

2007-07-24

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged progressively by amassing cell-cleaning systems from different sources, but not by acquisition of novel DNA repair systems. Our reconstruction of the genomic evolution of the Deinococcus-Thermus phylum indicates that the corresponding set of enzymes proliferated mainly in the common ancestor of Deinococcus. Results of the comparative analysis weaken the arguments for a role of higher-order chromosome alignment structures in resistance; more clearly define and substantially revise downward the number of uncharacterized genes that might participate in DNA repair and contribute to

High temperature creep strength of Advanced Radiation Resistant Oxide Dispersion Strengthened Steels

Energy Technology Data Exchange (ETDEWEB)

Noh, Sanghoon; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Austenitic stainless steel may be one of the candidates because of good strength and corrosion resistance at the high temperatures, however irradiation swelling well occurred to 120dpa at high temperatures and this leads the decrease of the mechanical properties and dimensional stability. Compared to this, ferritic/martensitic steel is a good solution because of excellent thermal conductivity and good swelling resistance. Unfortunately, the available temperature range of ferritic/martensitic steel is limited up to 650 .deg. C. ODS steel is the most promising structural material because of excellent creep and irradiation resistance by uniformly distributed nano-oxide particles with a high density which is extremely stable at the high temperature in ferritic/martensitic matrix. In this study, high temperature strength of advanced radiation resistance ODS steel was investigated for the core structural material of next generation nuclear systems. ODS martensitic steel was designed to have high homogeneity, productivity and reproducibility. Mechanical alloying, hot isostactic pressing and hot rolling processes were employed to fabricate the ODS steels, and creep rupture test as well as tensile test were examined to investigate the behavior at high temperatures. ODS steels were fabricated by a mechanical alloying and hot consolidation processes. Mechanical properties at high temperatures were investigated. The creep resistance of advanced radiation resistant ODS steels was more superior than those of ferritic/ martensitic steel, austenitic stainless steel and even a conventional ODS steel.

Development of radiation resistant organic composites for cryogenic use

International Nuclear Information System (INIS)

Nishijima, S.

1997-01-01

The mechanism of the radiation induced degradation of the mechanical properties in composite materials have been studied and based on the mechanism the radiation resistant organic composites for fusion magnet have been developing. It was found that the degradation was brought by the change of the fracture mode from tensile (or flexural) to shear failure. Consequently the intrinsic parameter which control the degradation was concluded to be the interlaminar shear strength. To develop the radiation resistant composites, therefore, means to develop the composites showing the radiation resistant interlaminar shear strength. The mechanism was confirmed using three dimensional fabric reinforced plastics which do not have the interlaminar area. The roles of matrix in the composites were also revealed. The effects of dose quality and irradiated temperature on the radiation induced degradation were also discussed and the selection standards of the components for radiation resistant composites were proposed

Enhanced radiation resistant fiber optics

Science.gov (United States)

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

1993-11-30

A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures.

Enhanced radiation resistant fiber optics

International Nuclear Information System (INIS)

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

1993-01-01

A process for producing an optical fiber having enhanced radiation resistance is provided, the process including maintaining an optical fiber within a hydrogen-containing atmosphere for sufficient time to yield a hydrogen-permeated optical fiber having an elevated internal hydrogen concentration, and irradiating the hydrogen-permeated optical fiber at a time while the optical fiber has an elevated internal hydrogen concentration with a source of ionizing radiation. The radiation source is typically a cobalt-60 source and the fiber is pre-irradiated with a dose level up to about 1000 kilorads of radiation. 4 figures

arXiv Radiation resistant LGAD design

CERN Document Server

Ferrero, M.; Boscardin, M.; Cartiglia, N.; Dalla Betta, G.F.; Galloway, Z.; Mandurrino, M.; Mazza, S.; Paternoster, G.; Ficorella, F.; Pancheri, L.; Sadrozinski, H-F W.; Sola, V.; Staiano, A.; Seiden, A.; Zhao, Y.

In this paper, we report on the radiation resistance of 50-micron thick LGAD detectors manufactured at the Fondazione Bruno Kessler employing several different doping combinations of the gain layer. LGAD detectors with gain layer doping of Boron, Boron low-diffusion, Gallium, Carbonated Boron and Carbonated Gallium have been designed and successfully produced. These sensors have been exposed to neutron fluences up to $\\phi_n \\sim 3 \\cdot 10^{16}\\; n/cm^2$ and to proton fluences up to $\\phi_p \\sim 9\\cdot10^{15}\\; p/cm^2$ to test their radiation resistance. The experimental results show that Gallium-doped LGADs are more heavily affected by initial acceptor removal than Boron-doped LGAD, while the presence of Carbon reduces initial acceptor removal both for Gallium and Boron doping. Boron low-diffusion shows a higher radiation resistance than that of standard Boron implant, indicating a dependence of the initial acceptor removal mechanism upon the implant width. This study also demonstrates that proton irradiati...

Synthesis and radiation resistance of fullerenes and fullerene derivatives

Energy Technology Data Exchange (ETDEWEB)

Shilin, V. A., E-mail: shilin@pnpi.spb.ru; Lebedev, V. T.; Sedov, V. P.; Szhogina, A. A. [St. Petersburg Nuclear Physics Institute, National Research Centre “Kurchatov Institute” (Russian Federation)

2016-07-15

The parameters of an electric-arc facility for the synthesis of fullerenes and endohedral metallofullerenes are optimized. The resistance of C{sub 60} and C{sub 70} fullerenes and C{sub 60}(OH){sub 30} and C{sub 70}(OH){sub 30} fullerenols against neutron irradiation is studied. It is established that the radiation resistance of the fullerenes is higher than that of the fullerenols, but the radiation resistance of the Gd@C{sub 2n} endometallofullerenes is lower than that of the corresponding Gd@C{sub 2n}(OH){sub 38} fullerenols. The radiation resistance of mixtures of Me@C{sub 2n}(OH){sub 38} (Me = Gd, Tb, Sc, Fe, and Pr) endometallofullerenes with C{sub 60}(OH){sub 30} is determined. The factors affecting the radiation resistance of the fullerenes and fullerenols are discussed.

Adriamycin resistance and radiation response

International Nuclear Information System (INIS)

Belli, J.A.; Harris, J.R.

1979-01-01

Mammalian cells (V79) in culture developed resistance to Adriamycin during continuous exposure to low levels of drug. This resistance was accompanied by change in x-ray survival properties which, in turn, depended upon the isolation of subpopulations from resistant sub lines. These changes in x-ray survival properties were characterized by reduced D/sub Q/ values and a decrease in the D/sub O/. However, these changes were not observed together in the same cell sub line. Adriamycin-resistant cells did not appear to be radiation damage repair deficient. Other phenotypic changes (cell morphology, DNA content and chromosome number) suggested mutational events coincident with the development of Adriamycin resistance

Archway for Radiation and Micrometeorite Occurrence Resistance

Science.gov (United States)

Giersch, Louis R.

2012-01-01

The environmental conditions of the Moon require mitigation if a long-term human presence is to be achieved for extended periods of time. Radiation, micrometeoroid impacts, high-velocity debris, and thermal cycling represent threats to crew, equipment, and facilities. For decades, local regolith has been suggested as a candidate material to use in the construction of protective barriers. A thickness of roughly 3m is sufficient protection from both direct and secondary radiation from cosmic rays and solar protons; this thickness is sufficient to reduce radiation exposure even during solar flares. NASA has previously identified a need for innovations that will support lunar habitats using lightweight structures because the reduction of structural mass translates directly into additional up and down mass capability that would facilitate additional logistics capacity and increased science return for all mission phases. The development of non-pressurized primary structures that have synergy with the development of pressurized structures is also of interest. The use of indigenous or in situ materials is also a well-known and active area of research that could drastically improve the practicality of human exploration beyond low-Earth orbit. The Archway for Radiation and Micrometeorite Occurrence Resistance (ARMOR) concept is a new, multifunctional structure that acts as radiation shielding and micrometeorite impact shielding for long-duration lunar surface protection of humans and equipment. ARMOR uses a combination of native regolith and a deployed membrane jacket to yield a multifunctional structure. ARMOR is a robust and modular system that can be autonomously assembled on-site prior to the first human surface arrival. The system provides protection by holding a sufficiently thick (3 m) archshaped shell of local regolith around a central cavity. The regolith is held in shape by an arch-shaped jacket made of strong but deployable material. No regolith processing is

Studies on the radiation resistances of bioburden for medical devices

International Nuclear Information System (INIS)

Sekiguchi, Masayuki; Tabei, Masae

1997-01-01

Radiation resistances of reference bacteria strains and the bioburden obtained from hypodermic needles were estimated with gamma- and electron- irradiators calibrated with NPL (National Physics Laboratory) alanine dosimeter. Radiation resistances of the TSB-bacteria suspension samples dried on glass test tubes showed about two times higher than those of the water-bacteria suspension dried on glass fiber paper or paper filter. Radiation resistances of the dried TSB-bacteria suspension samples irradiated by both gamma rays and electron beams were fluctuated. The overall increase ratio of radiation resistance was estimated by dividing D-values of TSB-bacteria suspension samples by that of water-bacteria suspension samples for individual bacteria. Then, the survival curve of hypodermic needle bioburden revised by the increase ratio was obtained, and which compared with that of standard distribution of radiation resistances of ISO(SDR). (author)

Tumourigenicity and radiation resistance of mesenchymal stem cells

DEFF Research Database (Denmark)

D'Andrea, Filippo Peder; Horsman, Michael Robert; Kassem, Moustapha

2012-01-01

Background. Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Material and methods....... Nontumourigenic (TERT4) and tumourigenic (TRET20) cell lines, from an immortalised mesenchymal stem cell line, were grown in culture prior to irradiation and gene expression analysis. Radiation resistance was measured using a clonogenic assay. Differences in gene expression between the two cell lines, both under...... the intercellular matrix. These results also indicate that cancer stem cells are more radiation resistant than stem cells of the same origin....

Radiation resistance of optical fibers, (10)

International Nuclear Information System (INIS)

Tsunoda, Tsunemi; Ara, Katsuyuki; Morimoto, Naoki; Sanada, Kazuo; Inada, Koichi.

1991-01-01

Optical fibers have many excellent characteristics such as the light weight of the material, insulation, the noninductivity of electromagnetic interference noise, the wide band of signal transmission, and small loss. Also in the field of atomic energy, the utilization of optical fibers is positively expanded, and the research on the method of application and so on has been advanced. However in optical fibers, there is the problem that color centers are formed at the relatively low level of radiation, and they are colored. Accordingly, for effectively utilizing optical fibers in radiation environment, it is indispensable to improve their radiation resistance. For the purpose of solving this problem, the authors have carried out the basic research on the effect that radiation exerts to optical fibers and the development of the optical fibers having excellent radiation resistance. For the purpose of expanding the range of application of GeO 2 -doped silica core fibers including GI type in radiation regions, the transmission characteristics of the fibers during irradiation were examined by using the Cl content as the parameter. Therefore, the results are reported. The fibers put to the test, the testing method and the results are described. (K.I.)

Radiation Resistance Test of Wireless Sensor Node and the Radiation Shielding Calculation

Energy Technology Data Exchange (ETDEWEB)

Li, Liqan; Sur, Bhaskar [Atomic Energy of Canada Limited, Ontario (Canada); Wang, Quan [University of Western Ontario, Ontario (Canada); Deng, Changjian [The University of Electronic Science and Technology, Chengdu (China); Chen, Dongyi; Jiang, Jin [Applied Physics Branch, Ontario (Korea, Republic of)

2014-08-15

A wireless sensor network (WSN) is being developed for nuclear power plants. Amongst others, ionizing radiation resistance is one essential requirement for WSN to be successful. This paper documents the work done in Chalk River Laboratories of Atomic Energy of Canada Limited (AECL) to test the resistance to neutron and gamma radiation of some WSN nodes. The recorded dose limit that the nodes can withstand before being damaged by the radiation is compared with the radiation environment inside a typical CANDU (CANada Deuterium Uranium) power plant reactor building. Shielding effects of polyethylene, cadmium and lead to neutron and gamma radiations are also analyzed using MCNP simulation. The shielding calculation can be a reference for the node case design when high dose rate or accidental condition (like Fukushima) is to be considered.

Study of radiation induced structural changes in nitrile rubber

International Nuclear Information System (INIS)

Cardona, F.; Hill, D.J.T.; Pomery, P.J.; Whittaker, A.K.

1996-01-01

Full text: Copolymers of butadiene (BD) and acrylonitrile (AN) (NBR rubber), have become important commercial material. NBR rubbers are part of a larger classification of products often referred to as special-purpose rubbers. Oil resistance is the most important property of nitrile rubbers, and refer to the ability of the vulcanised product to retain its original physical properties such as modulus, tensile strength, abrasion resistance and dimensions, while in contact with oils and fuels. Despite these reported advantages very few studies have been conducted on the radiation yields and structural changes in nitrile rubbers during exposure to high energy radiation. In this study we are investigating the stability against gamma and UV radiation, to different doses in vacuum, of butadiene, acrylonitrile and NBR copolymers with different composition ratio BD/AN. The mechanism of radiation induced structural changes is being investigated using experimental techniques such as ESR, NMR (Solid-state), FT-IR, RAMAN and UV spectroscopy. Also is being investigated the effect of irradiation on the mechanical properties of stressed and unstressed samples by TGA, DSC, DMA, Instron and Creep Test measurements. So far the main effect have been a marked radiation-induced loss of unsaturation in the butadiene units, cis to trans isomerization and formation of crosslink structures (intermolecular and intramolecular). One of the main challenges in the studies of NBR polymers is to observe directly the crosslinks produces by the radiation induced chemical reactions. IR spectroscopy is unsuitable because of the low molar absorbity of the peaks related to intermolecular crosslinking and the overlapping of the peaks (1630-1670 cm-1) related to intramolecular crosslinking (cyclization), with conjugated and nonconjugated (-C=C-; -C=N-) double bonds. A. K. Whittaker has shown that crosslink structures in PBD can be detected and measured directly using solid-state 13 C NMR. This technique

Isolation and identification of radiation resistant yeasts from sea water

International Nuclear Information System (INIS)

Park, Jong Cheon; Jeong, Yong Uk; Kim, Du Hong; Jo, Eun A

2011-12-01

This study was conducted to isolate radiation-resistant yeasts from sea water for development of application technology of radiation-resistant microorganism. · Isolation of 656 yeasts from sea water and selection of 2 radiation-resistant yeasts (D 10 value >3) · Identification of isolated yeasts as Filobasidium elegans sharing 99% sequence similarity · Characterization of isolated yeast with ability to repair of the DNA damage and membrane integrity to irradiation

A Novel Radiation-Resistant Yeast, Filobasidium elegans RRY1

Energy Technology Data Exchange (ETDEWEB)

Singh, Harinder; Kim, Ha Ram; Song, Hyun Pa; Lim, Sang Yong; Kim, Dong Ho [Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

2012-05-15

The tolerance to ionizing radiation stress is present among different classes and species of organisms. As listed by Rainey et al., ionizing radiation resistant organisms were isolated from a variety of different sources like processed/canned food items, paper industry, soil and water samples. Apart from extensively reported bacteria and Archea group, many fungal species like Aspergillus, Curvularia, Alternaria, Cryptococcus, and Ustilago maydis have been found to be resistant to ionizing radiation. However, different environmental sources are constantly been explored for novel radioresistant organisms, which can help in understanding the molecular mechanism behind these extreme stress responses. On the basis of this, present study was initiated to find novel radiation resistant yeast from sea water source

Development of radiation resistant PEEK insulation cable

International Nuclear Information System (INIS)

Mio, Keigo; Ogiwara, Norio; Hikichi, Yusuke; Furukori, Hisayoshi; Arai, Hideyuki; Nishizawa, Daiji; Nishidono, Toshiro

2009-04-01

Material characterization and development has been carried out for cable insulation suitable for use in the J-PARC 3-GeV RCS radiation environment. In spite of its high cost, PEEK (polyether-ether-ketone) has emerged as the leading candidate satisfying requirements of being non-halogen based, highly incombustible and with radiation resistant at least 10 MGy, along with the usual mechanical characteristics such as good elongation at break, which are needed in a cable insulation. Gamma-ray irradiation tests have been done in order to study radiation resistance of PEEK cable. Further, mechanical, electrical and fire retardant characteristics of a complete cable such as would be used at the J-PARC RCS were investigated. As a result, PEEK cables were shown to be not degraded by radiation up to at least 10 MGy, and thus could be expected to operate stably under the 3-GeV RCS radiation environment. (author)

Radiation-resistance assessment of IR fibres for ITER thermography diagnostic system

International Nuclear Information System (INIS)

Brichard, B.; Ierschot, S. van; Ooms, H.; Berghmans, F.; Reichle, R.; Pocheau, C.; Decreton, M.

2006-01-01

The actively cooled target plates in the divertor of ITER will be subjected to high thermal fluxes (∼ 10 MW/m 2 ). These target plates are compound structures of an armour material at the surface - either carbon fibre reinforced carbon (CFC) or tungsten - and a water cooled CuCrZr structure inside or below. The thermal limit of the interface between the two materials must not exceed 550 o C. Therefore, the temperature must be carefully monitored to prevent structural damages of the divertor plates. Non contact measurements of the temperature offer the advantage to avoid weakening of the cooling plate structure which is already quite complex to manufacture. Infrared thermography of the target surface is therefore considered as a possible solution. Recently a diagnostic concept for spectrally resolved ITER divertor thermography using optical fibres has been proposed by CEA-Cadarache. However, the divertor region will have to face high-radiation flux and the radiation-resistance of InfraRed (IR)-fibres must be evaluated. In collaboration with CEA-Cadarache, an irradiation program has been started at SCK-CEN (Mol, Belgium) with the aim to measure the radiation-induced absorption of different IR fibre candidates operating in the 1-5 μm range. We selected various commercially available IR technologies: ZrF 4 , Hollow-Waveguide, Sapphire and Chalcogenide. For wavelengths below 2 μm we also tested low-OH silica fibres. We carried out a gamma irradiation at a maximum dose-rate of 0.42 Gy/s up to a total dose of about 5000 Gy. We showed that the optical transmission of ZrF 4 fibres strongly decreased under gamma radiation, primarily for wavelengths below 2 μm. In this type of fibre typical optical losses can reach 50 % at 5000 Gy around 3 μm. Nevertheless, the optical transmission can be significantly recovered by performing a thermal annealing treatment at a temperature of 100 o C. We also irradiated a Silver-coated hollow waveguide fibre at the same dose-rate but up

Radiation resistivity of pure-silica core image guide

International Nuclear Information System (INIS)

Hayami, H.; Ishitani, T.; Kishihara, O.; Suzuki, K.

1988-01-01

Radiation resistivity of pure-silica core image guides were investigated in terms of incremental spectral loss and quality of pictures transmitted through the image guides. Radiation-induced spectral losses were measured so as to clarify the dependences of radiation resistivity on such parameters as core materials (OH and Cl contents), picture element dimensions, (core packing density and cladding thickness), number of picture elements and drawing conditions. As the results, an image guide with OH-and Cl-free pure-silica core, 30-45% in core packing density, and 1.8 ∼ 2.2 μm in cladding thickness showed the lowest loss. The parameters to design this image guide were almost the same as those to obtain a image guide with good picture quality. Radiation resistivity of the image guide was not dependent on drawing conditions and number of picture elements, indicating that the image guide has large allowable in production conditions and that reliable quality is constantly obtained in production. Radiation resistivity under high total doses was evaluated using the image guide with the lowest radiation-induced loss. Maximum usable lengths of the image guide for practical use under specific high total doses and maximum allowable total doses for the image guide in specific lengths were extrapolated. Picture quality in terms of radiation-induced degradation in color fidelity in the pictures transmitted through image guides was quantitatively evaluated in the chromaticity diagram based on the CIE standard colorimetric system and in the color specification charts according to three attributes of colors. The image guide with the least spectral incremental loss gives the least radiation-induced degradation in color fidelity in the pictures as well. (author)

Increased radiation resistance in lithium-counterdoped silicon solar cells

Science.gov (United States)

Weinberg, I.; Swartz, C. K.; Mehta, S.

1984-01-01

Lithium-counterdoped n(+)p silicon solar cells are found to exhibit significantly increased radiation resistance to 1-MeV electron irradiation when compared to boron-doped n(+)p silicon solar cells. In addition to improved radiation resistance, considerable damage recovery by annealing is observed in the counterdoped cells at T less than or equal to 100 C. Deep level transient spectroscopy measurements are used to identify the defect whose removal results in the low-temperature aneal. It is suggested that the increased radiation resistance of the counterdoped cells is primarily due to interaction of the lithium with interstitial oxygen.

Bacterial and archaeal resistance to ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Confalonieri, F; Sommer, S, E-mail: fabrice.confalonieri@u-psud.fr, E-mail: suzanne.sommer@u-psud.fr [University Paris-Sud, CNRS UMR8621, Institut de Genetique et Microbiologie, Batiments 400-409, Universite Paris-Sud, 91405 Orsay (France)

2011-01-01

Organisms living in extreme environments must cope with large fluctuations of temperature, high levels of radiation and/or desiccation, conditions that can induce DNA damage ranging from base modifications to DNA double-strand breaks. The bacterium Deinococcus radiodurans is known for its resistance to extremely high doses of ionizing radiation and for its ability to reconstruct a functional genome from hundreds of radiation-induced chromosomal fragments. Recently, extreme ionizing radiation resistance was also generated by directed evolution of an apparently radiation-sensitive bacterial species, Escherichia coli. Radioresistant organisms are not only found among the Eubacteria but also among the Archaea that represent the third kingdom of life. They present a set of particular features that differentiate them from the Eubacteria and eukaryotes. Moreover, Archaea are often isolated from extreme environments where they live under severe conditions of temperature, pressure, pH, salts or toxic compounds that are lethal for the large majority of living organisms. Thus, Archaea offer the opportunity to understand how cells are able to cope with such harsh conditions. Among them, the halophilic archaeon Halobacterium sp and several Pyrococcus or Thermococcus species, such as Thermococcus gammatolerans, were also shown to display high level of radiation resistance. The dispersion, in the phylogenetic tree, of radioresistant prokaryotes suggests that they have independently acquired radioresistance. Different strategies were selected during evolution including several mechanisms of radiation byproduct detoxification and subtle cellular metabolism modifications to help cells recover from radiation-induced injuries, protection of proteins against oxidation, an efficient DNA repair tool box, an original pathway of DNA double-strand break repair, a condensed nucleoid that may prevent the dispersion of the DNA fragments and specific radiation-induced proteins involved in

Diversity of ionizing radiation-resistant bacteria obtained from the Taklimakan Desert.

Science.gov (United States)

Yu, Li Zhi-Han; Luo, Xue-Song; Liu, Ming; Huang, Qiaoyun

2015-01-01

So far, little is known about the diversity of the radiation-resistant microbes of the hyperarid Taklimakan Desert. In this study, ionizing radiation (IR)-resistant bacteria from two sites in Xinjiang were investigated. After exposing the arid (water content of 0.8 ± 0.3%) and non-arid (water content of 21.3 ± 0.9%) sediment samples to IR of 3000 Gy using a (60)Co source, a total of 52 γ-radiation-resistant bacteria were isolated from the desert sample. The 16S rRNA genes of all isolates were sequenced. The phylogenetic tree places these isolates into five groups: Cytophaga-Flavobacterium-Bacteroides, Proteobacteria, Deinococcus-Thermus, Firmicutes, and Actinobacteria. Interestingly, this is the first report of radiation-resistant bacteria belonging to the genera Knoellia, Lysobacter, Nocardioides, Paracoccus, Pontibacter, Rufibacter and Microvirga. The 16s rRNA genes of four isolates showed low sequence similarities to those of the published species. Phenotypic analysis showed that all bacteria in this study are able to produce catalase, suggesting that these bacteria possess reactive oxygen species (ROS)-scavenging enzymes. These radiation-resistant bacteria also displayed diverse metabolic properties. Moreover, their radiation resistances were found to differ. The diversity of the radiation-resistant bacteria in the desert provides further ecological support for the hypothesis that the ionizing-radiation resistance phenotype is a consequence of the evolution of ROS-scavenging systems that protect cells against oxidative damage caused by desiccation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Basic design of radiation-resistant LVDTs: Linear Variable Differential Transformer

Energy Technology Data Exchange (ETDEWEB)

Sohn, J. M.; Park, S. J.; Kang, Y. H. (and others)

2008-02-15

A LVDT(Linear Variable Differential Transformer) for measuring the pressure level was used to measure the pressure of a nuclear fuel rod during the neutron irradiation test in a research reactor. A LVDT for measuring the elongation was also used to measure the elongation of nuclear fuels, and the creep and fatigue of materials during a neutron irradiation test in a research reactor. In this report, the basic design of two radiation-resistant LVDTs for measuring the pressure level and elongation are described. These LVDTs are used a under radiation environment such as a research reactor. In the basic design step, we analyzed the domestic and foreign technical status for radiation-resistant LVDTs, made part and assembly drawings and established simple procedures for their assembling. Only a few companies in the world can produce radiation-resistant LVDTs. Not only these are extremely expensive, but the prices are continuously rising. Also, it takes a long time to procure a LVDT, as it can only be bought about by an order-production. The localization of radiation-resistant LVDTs is necessary in order to provide them quickly and at a low cost. These radiation-resistant LVDTs will be used at neutron irradiation devices such as instrumented fuel capsules, special purpose capsules and a fuel test loop in research reactors. We expect that the use of neutron irradiation tests will be revitalized by the localization of radiation-resistant LVDTs.

Chemical structure and physical properties of radiation-induced crosslinking of polytetrafluoroethylene

International Nuclear Information System (INIS)

Oshima, Akihiro; Ikeda, Shigetoshi; Katoh, Etsuko; Tabata, Yoneho

2001-01-01

The chemical structure and physical properties of polytetrafluoroethylene (PTFE) that has been crosslinked by radiation have been studied by various methods. It has been found that a Y-type crosslinking structure and a Y-type structure incorporating a double bond (modified Y-type) is formed in PTFE by radiation-crosslinking in the molten state. In addition, various types of double bond structures, excluding the crosslinking site, have been identified. The crosslinked PTFE has a good light transparency due to the loss of crystallites, whilst it retains the excellent properties of electrical insulation and heat resistance. The coefficient of abrasion and the permanent creep are also greatly improved by crosslinking

Gene Expression Analysis of Four Radiation-resistant Bacteria

OpenAIRE

Gao, Na; Ma, Bin-Guang; Zhang, Yu-Sheng; Song, Qin; Chen, Ling-Ling; Zhang, Hong-Yu

2009-01-01

To investigate the general radiation-resistant mechanisms of bacteria, bioinformatic method was employed to predict highly expressed genes for four radiation-resistant bacteria, i.e. Deinococcus geothermalis (D. geo), Deinococcus radiodurans (D. rad), Kineococcus radiotolerans (K. rad) and Rubrobacter xylanophilus (R. xyl). It is revealed that most of the three reference gene sets, i.e. ribosomal proteins, transcription factors and major chaperones, are generally highly expressed in the four ...

Development of application technology of radiation-resistant microorganism

International Nuclear Information System (INIS)

Kim, Dong Ho; Lim, Sang Yong; Joe, Min Ho; Jung, Jin Woo; Jung, Sun Wook; Song, Du Sup; Choi, Young Ji

2009-02-01

The scope of the project is divided into of three parts; (i) to define the survival strategy of radiation-resistant microbes, especially Deinococcus (ii) acquisition of gene resources encoding the novel protein and related with the production of functional materials (iii) development of control technology against radiation-resistant microbes. To this aim, first, the whole transcriptional response of the D. radiodurans strain haboring pprI mutation, which plays an important role in radiation resistance, was analyzed by cDNA microarray. The anti-oxidant activity of the major carotenoid of D. radiodurans, deinoxanthin, was analyzed and the strain was constructed, in which the gene necessary for bio- synthesis of deinoxanthin is deleted. The response to cadmium of D. radiodurans was also investigated through cDNA microarray analysis. Radiogenic therapy, one of the cancer treatments, is designed to use radiation-inducible gene for the treatment. To develop the gene-transfer vehicle for radiogenic therapy, we have investigated the virulence mechanism of Salmonella, which is tumor-targeting bacteria and studied the synergistic effect of some anti-cancer agents on radiation treatment for cancer. Finally, we confirmed that irradiation could decompose a fungus toxin, patulin, into various harmless by-products

Development of application technology of radiation-resistant microorganism

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong Ho; Lim, Sang Yong; Joe, Min Ho; Jung, Jin Woo; Jung, Sun Wook; Song, Du Sup; Choi, Young Ji [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-02-15

The scope of the project is divided into of three parts; (i) to define the survival strategy of radiation-resistant microbes, especially Deinococcus (ii) acquisition of gene resources encoding the novel protein and related with the production of functional materials (iii) development of control technology against radiation-resistant microbes. To this aim, first, the whole transcriptional response of the D. radiodurans strain haboring pprI mutation, which plays an important role in radiation resistance, was analyzed by cDNA microarray. The anti-oxidant activity of the major carotenoid of D. radiodurans, deinoxanthin, was analyzed and the strain was constructed, in which the gene necessary for bio- synthesis of deinoxanthin is deleted. The response to cadmium of D. radiodurans was also investigated through cDNA microarray analysis. Radiogenic therapy, one of the cancer treatments, is designed to use radiation-inducible gene for the treatment. To develop the gene-transfer vehicle for radiogenic therapy, we have investigated the virulence mechanism of Salmonella, which is tumor-targeting bacteria and studied the synergistic effect of some anti-cancer agents on radiation treatment for cancer. Finally, we confirmed that irradiation could decompose a fungus toxin, patulin, into various harmless by-products.

Metal-nanotube composites as radiation resistant materials

Energy Technology Data Exchange (ETDEWEB)

González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel, E-mail: m.kiwi.t@gmail.com [Departamento de Física, Facultad de Ciencias, CEDENNA, Universidad de Chile, Casilla 653, Santiago 7800024 (Chile); Duin, Adri C. T. van [Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); So, Kang Pyo; Li, Ju [Department of Nuclear Science and Engineering and Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bringa, Eduardo M. [CONICET and Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza 5500 (Argentina)

2016-07-18

The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

Metal-nanotube composites as radiation resistant materials

International Nuclear Information System (INIS)

González, Rafael I.; Valencia, Felipe; Mella, José; Kiwi, Miguel; Duin, Adri C. T. van; So, Kang Pyo; Li, Ju; Bringa, Eduardo M.

2016-01-01

The improvement of radiation resistance in nanocomposite materials is investigated by means of classical reactive molecular dynamics simulations. In particular, we study the influence of carbon nanotubes (CNTs) in an Ni matrix on the trapping and possible outgassing of He. When CNTs are defect-free, He atoms diffuse alongside CNT walls and, although there is He accumulation at the metal-CNT interface, no He trespassing of the CNT wall is observed, which is consistent with the lack of permeability of a perfect graphene sheet. However, when vacancies are introduced to mimic radiation-induced defects, He atoms penetrate CNTs, which play the role of nano-chimneys, allowing He atoms to escape the damaged zone and reduce bubble formation in the matrix. Consequently, composites made of CNTs inside metals are likely to display improved radiation resistance, particularly when radiation damage is related to swelling and He-induced embrittlement.

A novel radiation-induced p53 mutation is not implicated in radiation resistance via a dominant-negative effect.

Directory of Open Access Journals (Sweden)

Yunguang Sun

Full Text Available Understanding the mutations that confer radiation resistance is crucial to developing mechanisms to subvert this resistance. Here we describe the creation of a radiation resistant cell line and characterization of a novel p53 mutation. Treatment with 20 Gy radiation was used to induce mutations in the H460 lung cancer cell line; radiation resistance was confirmed by clonogenic assay. Limited sequencing was performed on the resistant cells created and compared to the parent cell line, leading to the identification of a novel mutation (del at the end of the DNA binding domain of p53. Levels of p53, phospho-p53, p21, total caspase 3 and cleaved caspase 3 in radiation resistant cells and the radiation susceptible (parent line were compared, all of which were found to be similar. These patterns held true after analysis of p53 overexpression in H460 cells; however, H1299 cells transfected with mutant p53 did not express p21, whereas those given WT p53 produced a significant amount, as expected. A luciferase assay demonstrated the inability of mutant p53 to bind its consensus elements. An MTS assay using H460 and H1299 cells transfected with WT or mutant p53 showed that the novel mutation did not improve cell survival. In summary, functional characterization of a radiation-induced p53 mutation in the H460 lung cancer cell line does not implicate it in the development of radiation resistance.

Radiation-resistance of polyurethane pipes for cooling liquid in BES III

International Nuclear Information System (INIS)

Li Xunfeng; Zheng Lifang; Ji Quan; Wu Ping; Wang Li

2009-01-01

Gamma ray radiation and neutron radiation are predominant in the working conditions of BES III, and the radiation-resistance aging of polyurethane pipes is very important in this condition, as the pipes of cooling liquid for beam pipe and SCQ (superconducting quadrupole) vacuum pipe in BESIII. Polyester polyurethane pipes and polyether polyurethane pipes were irradiated by gamma ray and neutron. The radiation doses were as much as ten years' doses in BES. Pressure test, FTIR and thermal analysis were used to study the radiation-resistance of these two kinds of polyurethane pipes. The results show that the radiation-resistance and thermal stability of polyester polyurethane pipes are prior to those of polyether polyurethane pipes, and the pressure resistance of polyester polyurethane pipes is almost maintained after the irradiation by gamma ray and neutron, but the polyether polyurethane pipes can be aged and ruptured after the irradiation by neutron. (authors)

Tumourigenicity and radiation resistance of mesenchymal stem cells.

Science.gov (United States)

D'Andrea, Filippo P; Horsman, Michael R; Kassem, Moustapha; Overgaard, Jens; Safwat, Akmal

2012-05-01

Cancer stem cells are believed to be more radiation resistant than differentiated tumour cells of the same origin. It is not known, however, whether normal nontransformed adult stem cells share the same radioresistance as their cancerous counterpart. Nontumourigenic (TERT4) and tumourigenic (TRET20) cell lines, from an immortalised mesenchymal stem cell line, were grown in culture prior to irradiation and gene expression analysis. Radiation resistance was measured using a clonogenic assay. Differences in gene expression between the two cell lines, both under nontreated and irradiated conditions, were assessed with microarrays (Affymetrix Human Exon 1.0 ST array). The cellular functions affected by the altered gene expressions were assessed through gene pathway mapping (Ingenuity Pathway Analysis). Based on the clonogenic assay the nontumourigenic cell line was found to be more sensitive to radiation than the tumourigenic cell line. Using the exon chips, 297 genes were found altered between untreated samples of the cell lines whereas only 16 genes responded to radiation treatment. Among the genes with altered expression between the untreated samples were PLAU, PLAUR, TIMP3, MMP1 and LOX. The pathway analysis based on the alteration between the untreated samples indicated cancer and connective tissue disorders. This study has shown possible common genetic events linking tumourigenicity and radiation response. The PLAU and PLAUR genes are involved in apoptosis evasion while the genes TIMP3, MMP1 and LOX are involved in regulation of the surrounding matrix. The first group may contribute to the difference in radiation resistance observed and the latter could be a major contributor to the tumourigenic capabilities by degrading the intercellular matrix. These results also indicate that cancer stem cells are more radiation resistant than stem cells of the same origin.

Operation and radiation resistance of a FOXFET biasing structure for silicon strip detectors

Energy Technology Data Exchange (ETDEWEB)

Laakso, M [Particle Detector Group, Fermilab, Batavia, IL (United States) Research Inst. for High Energy Physics (SEFT), Helsinski (Finland); Singh, P; Engels, E Jr; Shepard, J; Shepard, P F [Dept. of Physics and Astronomy, Univ. Pittsburgh, PA (United States)

1993-03-01

AC-coupled strip detectors biased with a FOXFET transistor structure have been studied. Measurement results for the basic operational characteristics of the FOXFET are presented together with a brief description of the physics underlying its operation. Radiation effects were studied using photons from a [sup 137]Cs source. Changes in the FOXFET characteristics as a function of radiation dose up to 1 Mrad are reported. Results about the effect of radiation on the noise from a FOXFET biased detector are discribed. (orig.).

Operation and radiation resistance of a FOXFET biasing structure for silicon strip detectors

International Nuclear Information System (INIS)

Laakso, M.; Helsinki Univ.; Singh, P.; Engels, E. Jr.; Shepard, P.

1992-02-01

AC-coupled strip detectors biased with a FOXFET transistor structure have been studied. Measurement results for the basic operational characteristics of the FOXFET are presented together with a brief description of the physics underlying its operation. Radiation effects were studied using photons from a 137 Cs source. Changes in the FOXFET characteristics as a function of radiation dose up to 1 MRad are reported. Results about the effect of radiation on the noise from a FOXFET biased detector are described. 13 refs

Chemical structure and radiation stability of solid crystalline antibiotics: thiamphenicol and chloramphenicol

International Nuclear Information System (INIS)

Varshney, Lalit; Soe Nwe

1997-01-01

Antibiotics in solid state show significant radiation resistance and some of them are exposed to gamma or electron beam irradiation for sterilization. Even small radiation degradation in solid state antibiotics is not desirable. Two antibiotics namely thiamphenicol (TPL) and chloramphenicol (CPL) having similar chemical and solid state structure were irradiated at different graded radiation doses to study their stability. Differential scanning calorimetry (DSC) was used to evaluate purity, entropy of radiation processing, heat of fusion and melting point. (author). 3 refs., 1 tab

Radiation resistance of a hemolytic micrococcus isolated from chicken meat

International Nuclear Information System (INIS)

Tan, S.T.

1982-01-01

The effects of environmental factors on a highly radiation-resistant hemolytic micrococcus isolated from chicken meat were studied. NaCl tolerance and gamma radiation resistance of the cells were growth phase-related. The cells were resistant to injury from drying or freezing/thawing. Under certain conditions, cells in the frozen state required approximately 5 Mrad to inactivate 90% of the population; 0.2 Mrad injured an equivalent proportion. Survival curve of the cells heated at 60 0 C showed a unique pattern which was in three distinct phases. Heat-stressed cells were much more sensitive to radiation inactivation than unheated cells. When suspended in fresh m-Plate Count Broth (PCB), the injured cells repaired without multiplication during incubation at 32 0 C. The repair process in this bacterium, however, was slower compared to thermally injured organisms studied by other workers. An improved replica-plating technique, was devised for isolation of radiation-sensitive mutants of pigmented bacteria. A simple method to demonstrate radiation-inducible radiation resistance in microbial cells was developed. The new method required neither washing/centrifugation nor procedures for cell enumeration. Mutagenesis treatment of radiation-resistant micrococcal bacterium with N-methyl-N'-nitro-N-nitrosoguanidine (NTG) followed by FPR and screening steps resulted in isolation of two radiation-sensitive mutants. The more sensitive mutant strain, designated as 702, was seven times as sensitive to gamma or UC radiation as the wild type. No apparent difference was observed between 702 and the wild type in (1) cell morphology, colonial morphology, and pigment production or (2) tolerance to NaCl, drying/storage, freezing/thawing, and heating. Sodium dodecyl sulfate treatment (for curing) of wild type did not result in isolation of a radiation-sensitive mutant

Global Current Circuit Structure in a Resistive Pulsar Magnetosphere Model

Science.gov (United States)

Kato, Yugo. E.

2017-12-01

Pulsar magnetospheres have strong magnetic fields and large amounts of plasma. The structures of these magnetospheres are studied using force-free electrodynamics. To understand pulsar magnetospheres, discussions must include their outer region. However, force-free electrodynamics is limited in it does not handle dissipation. Therefore, a resistive pulsar magnetic field model is needed. To break the ideal magnetohydrodynamic (MHD) condition E\\cdot B=0, Ohm’s law is used. This work introduces resistivity depending upon the distance from the star and obtain a self-consistent steady state by time integration. Poloidal current circuits form in the magnetosphere while the toroidal magnetic field region expands beyond the light cylinder and the Poynting flux radiation appears. High electric resistivity causes a large space scale poloidal current circuit and the magnetosphere radiates a larger Poynting flux than the linear increase outside of the light cylinder radius. The formed poloidal-current circuit has width, which grows with the electric conductivity. This result contributes to a more concrete dissipative pulsar magnetosphere model.

Improvement of radiation resistance for polytetrafluoroethylene(PTFE) by radiation cross-linking

International Nuclear Information System (INIS)

Oshima, Akihiro; Tabata, Yoneho; Ikeda, Shigetoshi; Seguchi, Tadao.

1996-01-01

The crosslinked polytetrafluoroethylene(PTFE) was prepared by electron beams irradiation technique in the molten state at 340degC ± 3degC in inert gas atmosphere. The crosslinking density was changed by the irradiation dose. The radiation resistance of crosslinked PTFE was investigated on the mechanical properties after irradiation by γ-rays at room temperature under vacuum and in air. The dose at half value of elongation at break was about 1MGy for 500kGy-crosslinked PTFE, while the dose for non-crosslinked PTFE was only 3.5kGy. It was found that the radiation resistance of PTFE was extremely improved by crosslinking. (author)

Ways of providing radiation resistance of magnetic field semiconductor sensors

CERN Document Server

Bolshakova, I A; Holyaka, R; Matkovskii, A; Moroz, A

2001-01-01

Hall magnetic field sensors resistant to hard ionizing irradiation are being developed for operation under the radiation conditions of space and in charged particle accelerators. Radiation resistance of the sensors is first determined by the properties of semiconductor materials of sensitive elements; we have used microcrystals and thin layers of III-V semiconductors. Applying complex doping by rare-earth elements and isovalent impurities in certain proportions, we have obtained magnetic field sensors resistant to irradiation by fast neutrons and gamma-quanta. Tests of their radiation resistance were carried out at IBR-2 at the Joint Institute for Nuclear Research (Dubna). When exposed to neutrons with E=0.1-13 MeV and intensity of 10 sup 1 sup 0 n cm sup - sup 2 s sup - sup 1 , the main parameter of the sensors - their sensitivity to magnetic fields - changes by no more than 0.1% up to fluences of 10 sup 1 sup 4 n cm sup - sup 2. Further improvement of radiation resistance of sensor materials is expected by ...

Study of surface properties of ATLAS12 strip sensors and their radiation resistance

Energy Technology Data Exchange (ETDEWEB)

Mikestikova, M., E-mail: mikestik@fzu.cz [Academy of Sciences of the Czech Republic, Institute of Physics, Na Slovance 2, 18221 Prague 8 (Czech Republic); Allport, P.P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J.P.; Wilson, J.A. [School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT (United Kingdom); Kierstead, J.; Kuczewski, P.; Lynn, D. [Brookhaven National Laboratory, Physics Department and Instrumentation Division, Upton, NY 11973-5000 (United States); Hommels, L.B.A. [Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Ullan, M. [Centro Nacional de Microelectronica (IMB-CNM, CSIC), Campus UAB-Bellaterra, 08193 Barcelona (Spain); Bloch, I.; Gregor, I.M.; Tackmann, K. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Hauser, M.; Jakobs, K.; Kuehn, S. [Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str. 3, D-79104 Freiburg (Germany); and others

2016-09-21

A radiation hard n{sup +}-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the “ATLAS ITk Strip Sensor collaboration” and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in “punch-through protection” (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×10{sup 16} n{sub eq}/cm{sup 2}, by reactor neutron fluence of 1×10{sup 15} n{sub eq}/cm{sup 2} and by gamma rays from {sup 60}Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07. - Highlights: �

Thermal resistance of aluminum gravity heaГІ pipe with threaded capillary structure

Directory of Open Access Journals (Sweden)

Nikolaenko Yu. E.

2017-10-01

Full Text Available The results of an experimental study of the thermal resistance of an aluminum gravitational heat pipe with isobutane (R600a as a working fluid under conditions of heat removal of natural air convection are presented. Comparison of the thermal resistance of an aluminum gravitational heat pipe with a threaded capillary structure and the thermal resistance of an aluminum thermosyphon of the same size, having a smooth surface of the body in the evaporation zone, is given. It is shown that in the range of values of the input heat flux from 5 to 50 W the thermal resistance of the gravitational heat pipe is substantially lower than the thermal resistance of the thermosiphon. The studies were conducted both without the use of additional radiators in the condensation zone of heat transfer devices, and with the use of one, two and three radiators.

Radiation resistance of wide-bandgap semiconductor power transistors

Energy Technology Data Exchange (ETDEWEB)

Hazdra, Pavel; Popelka, Stanislav [Department of Microelectronics, Czech Technical University in Prague (Czech Republic)

2017-04-15

Radiation resistance of state-of-the-art commercial wide-bandgap power transistors, 1700 V 4H-SiC power MOSFETs and 200 V GaN HEMTs, to the total ionization dose was investigated. Transistors were irradiated with 4.5 MeV electrons with doses up to 2000 kGy. Electrical characteristics and introduced defects were characterized by current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) measurements. Results show that already low doses of 4.5 MeV electrons (>1 kGy) cause a significant decrease in threshold voltage of SiC MOSFETs due to embedding of the positive charge into the gate oxide. On the other hand, other parameters like the ON-state resistance are nearly unchanged up to the dose of 20 kGy. At 200 kGy, the threshold voltage returns back close to its original value, however, the ON-state resistance increases and transconductance is lowered. This effect is caused by radiation defects introduced into the low-doped drift region which decrease electron concentration and mobility. GaN HEMTs exhibit significantly higher radiation resistance. They keep within the datasheet specification up to doses of 2000 kGy. Absence of dielectric layer beneath the gate and high concentration of carriers in the two dimensional electron gas channel are the reasons of higher radiation resistance of GaN HEMTs. Their degradation then occurs at much higher doses due to electron mobility degradation. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of ionizing radiation on structural and conductive properties of copper nanotubes

Science.gov (United States)

Zdorovets, M. V.; Borgekov, D. B.; Kenzhina, I. E.; Kozlovskiy, A. L.

2018-01-01

The use of electron radiation is an effective tool for stimulating a controlled modification of structural and conductive properties of nanomaterials in modern materials science. The paper presents the results of studies of the influence of various types of radiation on structural and conductive properties of copper nanotubes obtained by electrochemical synthesis in pores of templates based on polyethylene terephthalate. Such methods as SEM, X-ray diffraction and EDS show that irradiation with a stream of high-energy electrons with doses of 50-250 kGy makes it possible to modify the crystal structure of nanotubes, increasing their conductivity and decreasing the resistance of nanostructures without destroying the structure.

CERN selects Fujikura's radiation resistant fiber

CERN Multimedia

2007-01-01

"Fujikura Europe Ltd. (search for Fujikura Europe) today announced that its radiation resistant singlemode optical fiber has been selected by CERN to provide communicaton links within the world's largest particle accelerator..."(2/3 page)

Radiation resistance of track etched membranes

International Nuclear Information System (INIS)

Buczkowski, M.; Sartowska, B.; Wawszczak, D.; Starosta, W.

2001-01-01

Track etched membranes (TEMs) obtained by irradiation of polymer films with heavy ions and subsequent etching of latent tracks can be applied in many fields and among others in biomedicine as well. It is important to know radiation resistance of TEMs because of wide use of radiation sterilization in the case of biomedical devices. Tensile properties of TEMs made of PET and PC films with the thickness of 10 μm after electron irradiation at different doses are known from literature. Nowadays TEMs are being manufactured from thicker (20 μm) PET and PC films as well as polyethylene naphthalate (PEN) films are proposed for TEMs. It seems to be important to get data about radiation resistance of new kinds of TEMs. Samples of polymer films made of PET and PEN with the thickness of 19-25 μm and TEMs made of such materials have been irradiated using 10 MeV electron beam with doses up to 990 kGy. Tensile properties and SEM photographs of the samples after irradiation are given in the paper

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

Science.gov (United States)

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

2016-06-01

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

DNA from radiation resistant human tumor cells transfers resistance to NIH/3T3 cells with varying degrees of penetrance

International Nuclear Information System (INIS)

Kasid, U.; Dritschilo, A.; Weichselbaum, R.

1987-01-01

Experimental evidence suggests that clinical radiation resistance may correlate with in vitro radiation survival parameters. Specifically, they isolated several cell lines from radioresistant head and neck carcinomas with D/sub 0/ values greater than 2 Gy. The authors co-transfected DNA from cell line SQ2OB (D/sub 0/ = 2.4 Gy) with the rhoSVNeO plasmid into NIH/3T3 cells (D/sub 0/ = 1.7 Gy). Antibiotic G418 resistant, transformed clones were isolated and confirmed by Southern blotting to contain human alu, as well as rhoSVNeO sequences. Screening for radiation resistance with 8Gy (Cs-137) revealed that 3 of 4 tested hybrid clones show a radiation survival intermediate between NIH/3T3 and SQ2OB. This suggests that radiation resistance is a dominant, transfectable phenotype of mammalian cells and can be expressed in more sensitive cells. Karyotyping of resistant hybrid clones shows the presence of double minute chromosomes. Secondary transfection results and experiments to clone the genetic factors responsible for radiation resistance are in progress and results will be reported

Radiation-resistant bacteria and their application to metal and radionuclides bioremediation

International Nuclear Information System (INIS)

Wang Jianlong

2004-01-01

Microorganisms have a number of applications in the nuclear industry, which would benefit from the use of radiation-resistant microorganisms. Environmentally isolated bacteria have shown to be resistant to gamma irradiation up to a dose of 30,000 Gy. It has also been reported that the presence of ionizing radiation may induce radio-resistance in bacteria. Recent demonstrations of the removal and immobilization of inorganic contaminants by microbial transformations, sorption and mineralization show the potential of both natural and engineered microorganisms as bioremedial tools. This review is to provide an overview of the application of radiation-resistant bacteria to decontamination of metal and radionuclide. (authors)

Radiation resistance of clinical Acinetobacter spp.: A need for concern

International Nuclear Information System (INIS)

Christensen, E.A.; Gerner-Smidt, P.; Kristensen, H.

1991-01-01

As part of an epidemiological investigation of hospital infections caused by Acinetobacter spp. the radiation resistance of 15 clinical isolates and four reference strains was assessed. The radiation resistance (in D-6 values, viz. the dose necessary for reducing the initial number of colony forming units by a factor of 10(6)) was, in general, higher in the isolates of A. radioresistens than in the isolates of the A. calcoaceticus-A. baumannii complex and of A. lwoffi. However, the least resistant isolates of A. radioresistens had a D-6 value equal to or lower than the most resistant isolates of the other groups. The lowest D-6 values found were for two of the reference strains. The highest D-6 value was 35 kGy. Three isolates of A. johnsonii could not survive long enough in a dried preparation to make an assessment of the D-6 values possible. The radiation resistance of the 15 clinical isolates in the present study was higher than the resistance found in a study of similar isolates in 1970

Radiation resistance of clinical Acinetobacter spp. : A need for concern

Energy Technology Data Exchange (ETDEWEB)

Christensen, E.A.; Gerner-Smidt, P.; Kristensen, H. (Control Department, Statens Seruminstitut, Copenhagen (Denmark))

1991-06-01

As part of an epidemiological investigation of hospital infections caused by Acinetobacter spp. the radiation resistance of 15 clinical isolates and four reference strains was assessed. The radiation resistance (in D-6 values, viz. the dose necessary for reducing the initial number of colony forming units by a factor of 10(6)) was, in general, higher in the isolates of A. radioresistens than in the isolates of the A. calcoaceticus-A. baumannii complex and of A. lwoffi. However, the least resistant isolates of A. radioresistens had a D-6 value equal to or lower than the most resistant isolates of the other groups. The lowest D-6 values found were for two of the reference strains. The highest D-6 value was 35 kGy. Three isolates of A. johnsonii could not survive long enough in a dried preparation to make an assessment of the D-6 values possible. The radiation resistance of the 15 clinical isolates in the present study was higher than the resistance found in a study of similar isolates in 1970.

Radiation-resistant vegetative bacteria in a proposed system of radappertization of meats

International Nuclear Information System (INIS)

Maxcy, R.B.; Rowley, D.B.

1978-01-01

After irradiation in the frozen state with 1 Mrad fresh minced pork or chicken contained approximately 10-100 colony-forming units of highly radiation resistant asporogenous bacteria per gram. Some of these had greater radiation resistance than Clostridium botulinum spores. Much of the radiation resistance was apparent as a shoulder in the death curve, which was markedly reduced by heating prior or subsequent to irradiation. Nature of the meat, such as variation in fat content (5-44%), had no significant effect on the radiation resistance of bacteria therein. Even though these bacteria were isolated from meat, it was not a favourable microenvironment for their growth. The water activity was too low. Heat sensitivity of isolates indicated the pre-irradiation enzyme inactivation treatment required for radappertization of meats would destroy or injure most vegetative cells. Thus, the combined process of heat, irradiation, and unfavourable microenvironment would ensure that these radiation resistant cells would not be a problem in radappertized meats. (author)

Study of decontamination and radiation resistance properties of Indian paints

International Nuclear Information System (INIS)

Shah, S.M.; Gopinathan, E.; Bhagwath, A.M.

1976-01-01

A brief introduction to the study of contamination and radiation resistance properties of Indian paints used as coating for structural materials in the nuclear industry is given. The general composition of paints such as epoxy, vinyl, alkyd, phenolic, chlesimated rubber, etc. is given. Method of sample preparation, processing and actual evaluation of decontaminability are described. The results have been discussed in terms of decontamination factors. Some recommendations based on the performance of the paints studied are also included. (K.B.)

Radiation induction of drug resistance in RIF-1: Correlation of tumor and cell culture results

International Nuclear Information System (INIS)

Moulder, J.E.; Hopwood, L.E.; Volk, D.M.; Davies, B.M.

1991-01-01

The RIF-1 tumor line contains cells that are resistant to various anti-neoplastic drugs, including 5-fluorouracil (5FU), methotrexate (MTX), adriamycin (ADR), and etoposide (VP16). The frequency of these drug-resistant cells is increased after irradiation. The frequency of drug-resistant cells and the magnitude of radiation-induced drug resistance are different in cell culture than in tumors. The dose-response and expression time relationships for radiation induction of drug resistance observed in RIF-1 tumors are unusual.We hypothesize that at high radiation doses in vivo, we are selecting for cells that are both drug resistant and radiation resistant due to microenvironmental factors, whereas at low radiation doses in vivo and all radiation doses in vitro, we are observing true mutants. These studies indicate that there can be significant differences in drug-resistance frequencies between tumors and their cell lines of origin, and that radiation induction of drug resistance depends significantly on whether the induction is done in tumors or in cell culture. These results imply that theories about the induction of drug resistance that are based on cell culture studies may be inapplicable to the induction of drug resistance in tumors

CERN selects Fujikura's radiation resistant fiber

CERN Multimedia

2007-01-01

"Fujikura recently announced that its radiation resistant single mode optical fiber has been selected by CERN, the European Laboratory for Particle Physics, to provide communication links within the world's largest particle accelerator - the Large Hadron Collider (LHC) - near Geneva, Switzerland." (1/2 page)

CERN selects Fujikura's radiation resistant fibre

CERN Multimedia

2007-01-01

"Fujikura today announced that its radiation resistant single mode optical fibre has been selected by CERN, the European Laboratory for Particle Physics, to provide communication links within the world's largest particle accelerator - the Large hadron Collider (LHC) - near Genevan, Switzerland. (1/2 page)

Radiation-resistant acquired immunity of vaccinated mice to Schistosoma mansoni

International Nuclear Information System (INIS)

Aitken, R.; Coulson, P.S.; Dixon, B.; Wilson, R.A.

1987-01-01

Vaccination of mice with attenuated cercariae of Schistosoma mansoni induces specific acquired resistance to challenge infection. This resistance is immunologically-mediated, possibly via a delayed-type hypersensitivity. Studies of parasite migration have shown that the protective mechanism operates most effectively in the lungs of vaccinated mice. We have probed the mechanism by exposing mice to 500 rads of gamma radiation before challenge infection. Our results show that the effector mechanism operative against challenge larvae is resistant to radiation. In contrast, classical immune responses are markedly suppressed by the same treatment. While leukocyte populations in the blood fall dramatically after irradiation, numbers of cells recoverable by bronchoalveolar lavage are unaffected. We suggest that vaccination with attenuated cercariae establishes populations of sensitized cells in the lungs which trigger the mechanism of resistance when challenge schistosomula migrate through pulmonary capillary beds. Although the cells may be partially disabled by irradiation, they remain responsive to worm antigens and thereby capable of initiating the elimination mechanism. This hypothesis would explain the radiation resistance of vaccine-induced immunity to S. mansoni

Radiation therapy for resistant sternal hydatid disease

International Nuclear Information System (INIS)

Ulger, S.; Barut, H.; Tunc, M.; Aydinkarahaliloglu, E.; Aydin, E.; Karaoglanoglu, N.; Gokcek, A.

2013-01-01

Hydatid disease is a zoonotic infectious disease for which there are known treatment procedures and effective antibiotics; however, there are resistant cases that do not respond to medication or surgery. We report a case diagnosed as hydatid disease of the chest wall and treated with radiation therapy (RT) after medical and surgical therapy had failed. In conclusion, RT represents an alternative treatment modality in resistant cases. (orig.)

Radiation effects evaluation for electrons sheaf in packages resistance in a Lasioderma serricorne, Plodia interpunctella and Sitophilus zeamais

International Nuclear Information System (INIS)

Alves, Juliana Nazare

2011-01-01

The plagues of stored products consist of a man problem, depreciating products and causing economical damages. Among these curses we have Lasioderma serricorne (F. 1792), Sitophilus zeamais (M. 1855) and Plodia interpunctella (H. 1813) known by infesting stored products as: grains, brans, flours, coffee, tobacco, dried fruits and spices. These curses perforate and penetrate the packages, ovipositing over the substratum. In this context the package plays a fundamental part, preventing the contact and curses' proliferation in the packed product. So, to protect the packed product and to prolong its shelf life, the package should have good mechanical resistance to tension and perforation, good sealing, good barrier properties and should not transfer odors nor strange flavors to the packed product. The ionizing radiation can cause structural changes in polymer packages, these changes are caused by the scission processes and reticulation of the polymers chains. These are concurrent processes and the predominance of one over the other depends on the chemical structure of the polymer, the irradiation conditions and specific factors of the material that will absorb the energy. This work had the objective to evaluate the changes in mechanical properties of package structures used to store granola, cereal bar and pasta, as well as its resistance to perforation by L. serricorne, P. interpunctella and S. zeamais, when submitted to electrons sheaf radiation. In this methodology were used five structures of commercially utilized packages to store granola, cereal bar and pasta composed by (Polypropylene bi-oriented metallic/Polypropylene bi-oriented coextruded - BOPPmet/BOPP 50 μm), (Polypropylene bi-oriented/Polypropylene - BOPP/PP 50 μm), Poli (ethylene terephthalate) metallic/Polypropylene bi-oriented coextruded - PETmet/BOPP 32 μm), Poli (ethylene terephthalate) /Polypropylene - PET/PP1 72 μm), Poli (ethylene terephthalate)/Polypropylene - PET/PP2 32 μm). The structures

Ultraviolet radiation resistance in Halobacterium salinarium

International Nuclear Information System (INIS)

Kristoff, S.R.

1985-01-01

An obvious characteristic of wild type H. salinarium is its red pigmentation. A non-pigmented mutant was isolated to test the role of pigmentation in UV radiation resistance. Survival curves of UV-irradiated wild type and mutant cells show that pigmentation does not play a direct role in protecting DNA from UV damage. Pigmentation does play a role, however, in repairing UV damage. UV-irradiated wild type cells show more efficient recovery by photoreactivation with 405 nm light than do UV-irradiated non-pigmented mutants. High internal cation concentrations found in H. salinarium may also be partly responsible for the relative resistance of H. salinarium to UV radiation by causing the DNA to assume a conformation less conducive to the production of pyrimidine dimers. In vitro irradiation of DNA extracted from H. salinarium, dissolved in solutions of different ionic strengths, indicate that pyrimidine dimers may not form as readily in DNA which is in an environment with high salt concentration

Radiation chemical transformations of some polyarylates by γ-radiation in vacuum

International Nuclear Information System (INIS)

Lyashevich, V.V.; Korshak, V.V.; Rodeh, V.V.; Timofeeva, G.I.

1976-01-01

A study was made of ageing by radiation of F-2 and D-9 polyarylates using γ-radiation in vacuum. Their high resistance to radiation was indicated. It was found that γ-radiation on polymers caused competing reactions to take place resulting in macromolecular breakdown and structure formation, which in the end produced threedimensional network formation. The initial formation of gel fractions was preceded by the formation of branched macromolecules. The radiation resistance of polyarylates depends on the type of lateral substituent at the central carbon atom of the initial bis-phenol and increases in the presence of a fluorene ring in the lateral chain. The radiation resistance of a lactone ring is lower than that of an ether bond of the main chain. It was shown that 0-hydroxy-ketone structures were formed in the polyarylates examined as a result of regrouping due to radiation. A basic system is proposed for chemical conversion of polyarylates by radiation

Development of new radiation resistant, fire-retardant cables. [Gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Hagiwara, Ko; Morita, Yosuke; Udagawa, Takashi (Japan Atomic Energy Research Inst., Takasaki, Gunma. Takasaki Radiation Chemistry Research Establishment); Fujimura, Shun-ichi; Oda, Eisuke

1982-12-01

For the cables for nuclear facilities, radiation resistance and fire-retardation are severely required. The authors took note of the fact that even in the existing cables for nuclear power plants, their mechanical properties are greatly degraded by the exposure to large dose (for example, 200 Mrad in PWR testing conditions), and attempted the improvement. They employed a new additive, bromated acenaphthylene condensate (con-BACN), which effectively gives radiation resistance and also is a good flame retarder, to be compounded to an insulation material, and examined the characteristics. In this paper, the features of con-BACN and the investigation of fire-retardant EPDM composition are described. As an initial composition, a small amount of zinc white, sulphur, stearic acid, noclac 224 (Ouchi-Shinko Chemicals, Co.), and antimony trioxide, 100 parts of tale and 45 parts of con-BACN were added to 100 parts of EPDM (propylene content 34 %, Japan Synthetic Rubber Co.). As the antiaging agent, it was decided to use phenol series No. 3 as a result of test. The fire-retardant EP rubber-composed cable was produced for trial, its insulation being fabricated, using a Furukawa's pressurized salt bath continuous vulcanizer. The tests of ..gamma..-irradiation, simulated LOCA and combustion were carried out, and the test results are reported. It was indicated that the cable resisted against high dose several times as much as 200 Mrad, and was suitable for the applications, in which the mechanical properties such as bending are required to be maintained after radiation exposure. It was also found that con-BACN was safe, and its properties of decomposition, concentration and acute toxicity were all very low.

Radiation-resistant beamline components at LAMPF

International Nuclear Information System (INIS)

Macek, R.J.; Grisham, D.L.; Lambert, J.e.; Werbeck, R.

1983-01-01

A variety of highly radiation-resistant beamline components have been successfully developed at LAMPF primarily for use in the target cells and beam stop area of the intense proton beamline. Design features and operating experience are reviewed for magnets, instrumentation, targets, vacuum seals, vacuum windows, collimators, and beam stops

Study of surface properties of ATLAS12 strip sensors and their radiation resistance

Science.gov (United States)

Mikestikova, M.; Allport, P. P.; Baca, M.; Broughton, J.; Chisholm, A.; Nikolopoulos, K.; Pyatt, S.; Thomas, J. P.; Wilson, J. A.; Kierstead, J.; Kuczewski, P.; Lynn, D.; Hommels, L. B. A.; Ullan, M.; Bloch, I.; Gregor, I. M.; Tackmann, K.; Hauser, M.; Jakobs, K.; Kuehn, S.; Mahboubi, K.; Mori, R.; Parzefall, U.; Clark, A.; Ferrere, D.; Sevilla, S. Gonzalez; Ashby, J.; Blue, A.; Bates, R.; Buttar, C.; Doherty, F.; McMullen, T.; McEwan, F.; O'Shea, V.; Kamada, S.; Yamamura, K.; Ikegami, Y.; Nakamura, K.; Takubo, Y.; Unno, Y.; Takashima, R.; Chilingarov, A.; Fox, H.; Affolder, A. A.; Casse, G.; Dervan, P.; Forshaw, D.; Greenall, A.; Wonsak, S.; Wormald, M.; Cindro, V.; Kramberger, G.; Mandić, I.; Mikuž, M.; Gorelov, I.; Hoeferkamp, M.; Palni, P.; Seidel, S.; Taylor, A.; Toms, K.; Wang, R.; Hessey, N. P.; Valencic, N.; Hanagaki, K.; Dolezal, Z.; Kodys, P.; Bohm, J.; Stastny, J.; Bevan, A.; Beck, G.; Milke, C.; Domingo, M.; Fadeyev, V.; Galloway, Z.; Hibbard-Lubow, D.; Liang, Z.; Sadrozinski, H. F.-W.; Seiden, A.; To, K.; French, R.; Hodgson, P.; Marin-Reyes, H.; Parker, K.; Jinnouchi, O.; Hara, K.; Sato, K.; Hagihara, M.; Iwabuchi, S.; Bernabeu, J.; Civera, J. V.; Garcia, C.; Lacasta, C.; Marti i Garcia, S.; Rodriguez, D.; Santoyo, D.; Solaz, C.; Soldevila, U.

2016-09-01

A radiation hard n+-in-p micro-strip sensor for the use in the Upgrade of the strip tracker of the ATLAS experiment at the High Luminosity Large Hadron Collider (HL-LHC) has been developed by the "ATLAS ITk Strip Sensor collaboration" and produced by Hamamatsu Photonics. Surface properties of different types of end-cap and barrel miniature sensors of the latest sensor design ATLAS12 have been studied before and after irradiation. The tested barrel sensors vary in "punch-through protection" (PTP) structure, and the end-cap sensors, whose stereo-strips differ in fan geometry, in strip pitch and in edge strip ganging options. Sensors have been irradiated with proton fluences of up to 1×1016 neq/cm2, by reactor neutron fluence of 1×1015 neq/cm2 and by gamma rays from 60Co up to dose of 1 MGy. The main goal of the present study is to characterize the leakage current for micro-discharge breakdown voltage estimation, the inter-strip resistance and capacitance, the bias resistance and the effectiveness of PTP structures as a function of bias voltage and fluence. It has been verified that the ATLAS12 sensors have high breakdown voltage well above the operational voltage which implies that different geometries of sensors do not influence their stability. The inter-strip isolation is a strong function of irradiation fluence, however the sensor performance is acceptable in the expected range for HL-LHC. New gated PTP structure exhibits low PTP onset voltage and sharp cut-off of effective resistance even at the highest tested radiation fluence. The inter-strip capacitance complies with the technical specification required before irradiation and no radiation-induced degradation was observed. A summary of ATLAS12 sensors tests is presented including a comparison of results from different irradiation sites. The measured characteristics are compared with the previous prototype of the sensor design, ATLAS07.

Radiation resistance of cable insulation and jacket materials for nuclear power plants

International Nuclear Information System (INIS)

Morita, Minoru; Kon, Shuji; Nishikawa, Ichiro

1978-01-01

The cables for use in nuclear power plants are required to satisfy the specific environmental resistance and excellent flame resistance as stipulated in IEEE Std. 383. The materials to be used to cables intended for this specific purpose of use must therefore be strictly tested so as to evaluate their flame resistance in addition to compliance with various environmental requirements, such as heat resistance, water-vapor resistance, and radiation resistance. This paper describes general information on radiation resistance and deterioration of various high-molecular materials, suggests the direction of efforts to be made to improve their properties including flame resistance of various rubber and plastic materials for cables to be used in nuclear power plants, and indicates the performance characteristics of such materials. (author)

Inactivation of the Radiation-Resistant Spoilage Bacterium Micrococcus radiodurans

Science.gov (United States)

Duggan, D. E.; Anderson, A. W.; Elliker, P. R.

1963-01-01

A simplified technique permitting the pipetting of raw puréed meats for quantitative bacteriological study is described for use in determining survival of these non-sporing bacteria, which are exceptionally resistant to radiation. Survival curves, using gamma radiation as the sterilizing agent, were determined in raw beef with four strains of Micrococcus radiodurans. Survival curves of the R1 strain in other meat substrates showed that survival was significantly greater in raw beef and raw chicken than in raw fish or in cooked beef. Resistance was lowest in the buffer. Cells grown in broth (an artificial growth medium) and resuspended in beef did not differ in resistance from cells that had been grown and irradiated in beef. Survival rate was statistically independent of the initial cell concentration, even though there appeared to be a correlation between lower death rate and lower initial cell concentrations. The initial viable count of this culture of the domesticated R1 strain in beef was reduced by a factor of about 10-5 by 3.0 megarad, and 4.0 megarad reduced the initial count by a factor of more than 10-9. Data suggest that M. radiodurans R1 is more resistant to radiation than spore-forming spoilage bacteria for which inactivation rates have been published. PMID:14063780

Development of superior radiation resistant materials and cables. 2

Energy Technology Data Exchange (ETDEWEB)

Ikehara, Junichiro; Kanemitsuya, Kazuhiko; Ohara, Hideo; Araki, Syogo; Hamachi, Katsuhiko [Mitsubishi Cable Industries Ltd., Tokyo (Japan)

1996-01-01

Many nuclear power plants have been constructed in Japan and electric power generation is now highly dependent on this technology. Therefore, the needs for facilities that will enrich and reprocess nuclear fuel from nuclear power stations will be high. As there are areas with high levels of radiation, the cables which can be used in these environments are needed. We have developed a superior radiation-resistant cable which uses halogen flame-retardant materials. This radiation-resistant cable consists of Ethylene-propylene rubber (EPDM) insulation and Chlorosulfonated polyethylene (CSM) sheath can be safely used in areas with high levels of radiation. We developed this product to aid in disaster prevention. Non-halogen, flame-retardant EPDM is used for the insulation, and low-halogen, flame-retardant CSM and new non-halogen, flame-retardant materials are used for the sheath. These cables have superior flame-retardant properties and generate little smoke on corrosive gas. This products can hence reduce the danger of a secondary disaster in a fire. We expect that these cables will find application in areas with high levels of radiation. (author).

Development of superior radiation resistant materials and cables. 2

International Nuclear Information System (INIS)

Ikehara, Junichiro; Kanemitsuya, Kazuhiko; Ohara, Hideo; Araki, Syogo; Hamachi, Katsuhiko

1996-01-01

Many nuclear power plants have been constructed in Japan and electric power generation is now highly dependent on this technology. Therefore, the needs for facilities that will enrich and reprocess nuclear fuel from nuclear power stations will be high. As there are areas with high levels of radiation, the cables which can be used in these environments are needed. We have developed a superior radiation-resistant cable which uses halogen flame-retardant materials. This radiation-resistant cable consists of Ethylene-propylene rubber (EPDM) insulation and Chlorosulfonated polyethylene (CSM) sheath can be safely used in areas with high levels of radiation. We developed this product to aid in disaster prevention. Non-halogen, flame-retardant EPDM is used for the insulation, and low-halogen, flame-retardant CSM and new non-halogen, flame-retardant materials are used for the sheath. These cables have superior flame-retardant properties and generate little smoke on corrosive gas. This products can hence reduce the danger of a secondary disaster in a fire. We expect that these cables will find application in areas with high levels of radiation. (author)

Radiation resistant ducted superconductive coil

International Nuclear Information System (INIS)

Schleich, A.

1976-01-01

The radiation-resistant ducted superconductive coil consists of a helically wound electrical conductor constituted by an electrically conductive core of superconductive material provided with a longitudinally extending cooling duct. The core is covered with a layer of inorganic insulating material and the duct is covered by an electrically conductive metallic gas-tight sheath. The metallic sheaths on adjacent turns of the coil are secured together. 2 Claims, 4 Drawing Figures

On the honeybee resistance to gamma radiation

International Nuclear Information System (INIS)

Courtois, G.; Lecomte, J.

1960-01-01

The honeybee, when irradiated by gamma radiations from a cobalt-60 source can stand a 18000 r dose without any apparent harm. Noticeable harm is observed for 90000 r. while immediate death of 100% of the individuals is obtained with a 200000 r dose. The physiological condition of the honeybee plays an important role in its resistance to gamma radiation. Reprint of a paper published in Annales de l'abeille, IV, 1959, p. 285-290 [fr

Some resistance mechanisms to ultraviolet radiation

International Nuclear Information System (INIS)

Alcantara D, D.

2002-12-01

The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

Data base of radiation-resistant dielectric and insulating materials

International Nuclear Information System (INIS)

Hama, Yoshimasa; Sunazuka, Hideo; Nashiyama, Isamu; Kakuta, Tsunemi.

1987-01-01

In the data base of radiation-resistant dielectric and insulating materials, the data format contains such items as to give the summary; the data sheet contains the data in concrete form of respective properties from the references; the sheet of references contains the references in the former two. In the above three, there are attached code No., data sheet No., reference No. and key words. In the three areas as radiation-resistant dielectric and insulating materials, i.e., organic materials, inorganic materials and optical fibers, the following are explained: data format, data sheet and objectives. (Mori, K.)

Superior radiation-resistant nanoengineered austenitic 304L stainless steel for applications in extreme radiation environments.

Science.gov (United States)

Sun, C; Zheng, S; Wei, C C; Wu, Y; Shao, L; Yang, Y; Hartwig, K T; Maloy, S A; Zinkle, S J; Allen, T R; Wang, H; Zhang, X

2015-01-15

Nuclear energy provides more than 10% of electrical power internationally, and the increasing engagement of nuclear energy is essential to meet the rapid worldwide increase in energy demand. A paramount challenge in the development of advanced nuclear reactors is the discovery of advanced structural materials that can endure extreme environments, such as severe neutron irradiation damage at high temperatures. It has been known for decades that high dose radiation can introduce significant void swelling accompanied by precipitation in austenitic stainless steel (SS). Here we report, however, that through nanoengineering, ultra-fine grained (UFG) 304 L SS with an average grain size of ~100 nm, can withstand Fe ion irradiation at 500 °C to 80 displacements-per-atom (dpa) with moderate grain coarsening. Compared to coarse grained (CG) counterparts, swelling resistance of UFG SS is improved by nearly an order of magnitude and swelling rate is reduced by a factor of 5. M(23)C(6) precipitates, abundant in irradiated CG SS, are largely absent in UFG SS. This study provides a nanoengineering approach to design and discover radiation tolerant metallic materials for applications in extreme radiation environments.

Genetic study of resistance to inhibitory effects of UV radiation in rice (Oryza sativa)

International Nuclear Information System (INIS)

Sato, T.; Kang, H.S.; Kumagai, T.

1994-01-01

Genetic analysis of resistance to the inhibitory effects of UV radiation on growth of rice (Oryza sativa L.) cultivars was carried out. Some experimental plants were grown in visible radiation supplemented with UV radiation containing a large amount of UV-B and a small amount of UV-C in a phytotron, while others were grown without UV radiation. The degree of resistance to UV radiation was estimated in terms of the degree of reduction caused by supplemental UV radiation in the fresh weight of the aboveground plant parts and the chlorophyll content per unit fresh weight. Fresh weight and chlorophyll content in F 2 plants generated by reciprocally crossing cv. Sasanishiki, a cultivar more resistant to UV radiation, and Norin 1, a cultivar less resistant to such radiation exhibited a normal frequency distribution. The heritabilities of these two properties in F 2 plants were low under conditions of non-supplemental UV radiation. Under elevated UV radiation, the F 2 population shifted to the lower range of fresh weight and chlorophyll content, and the means were close to those of Norin 1. The heritabilities of these two properties were the same in the reciprocal crosses, indicating that maternal inheritance was not involved. Inheritance of chlorophyll content per unit fresh weight was further determined in F 3 lines generated by self-fertilizing F 2 plants of Sasanishiki and Norin 1. The results showed that the F 3 population was segregated into three genotypes, namely, resistant homozygotes, segregated heterozygotes and sensitive homozygotes, with a ratio of 1:65:16. It was thus evident that the resistance to the inhibitory effect of elevated UV radiation in these rice plants was controlled by recessive polygenes. (author)

Radiation resistance of amorphous silicon alloy solar cells

International Nuclear Information System (INIS)

Hanak, J.J.; Chen, E.; Myatt, A.; Woodyard, J.R.

1987-01-01

The radiation resistance of a-Si alloy solar cells when bombarded by high energy particles is reviewed. The results of investigations of high energy proton radiation resistance of a-Si alloy thin film photovoltaic cells are reported. Irradiations were carried out with 200 keV and 1.00 MeV protons with fluences ranging betweeen 1E11 and 1E15 cm-2. Defect generation and passivation mechanisms were studied using the AM1 conversion efficiency and isochronal anneals. It is concluded that the primary defect generation mechanism results from the knock-on of Si and Ge in the intrinsic layer of the cells. The defect passivation proceeds by the complex annealing of Si and Ge defects and not by the simple migration of hydrogen

Breast cancers radiation-resistance: key role of the cancer stem cells marker CD24

International Nuclear Information System (INIS)

Bensimon, Julie

2013-01-01

This work focuses on the characterization of radiation-resistant breast cancer cells, responsible for relapse after radiotherapy. The 'Cancer Stem Cells' (CSC) theory describes a radiation-resistant cellular sub-population, with enhanced capacity to induce tumors and proliferate. In this work, we show that only the CSC marker CD24-/low defines a radiation resistant cell population, able to transmit the 'memory' of irradiation, expressed as long term genomic instability in the progeny of irradiated cells. We show that CD24 is not only a marker, but is an actor of radiation-response. So, CD24 expression controls cell proliferation in vitro and in vivo, and ROS level before and after irradiation. As a result, CD24-/low cells display enhanced radiation-resistance and genomic stability. For the first time, our results attribute a role to CD24-/low CSCs in the transmission of genomic instability. Moreover, by providing informations on tumor intrinsic radiation-sensitivity, CD24- marker could help to design new radiotherapy protocols. (author)

Effects of low dose gamma radiation on the early growth of red pepper and the resistance to subsquent high dose of radiation

Energy Technology Data Exchange (ETDEWEB)

Kim, J. S.; Baek, M. H.; Kim, D. H.; Lee, Y. K. [KAERI, Taejon (Korea, Republic of); Lee, Y. B. [Chungnam National Univ., Taejon (Korea, Republic of)

2001-05-01

Red pepper (capsicum annuum L. cv. Jokwang and cv. Johong) seeds were irradiated with the dose of 0{approx}50 Gy to investigated the effect of the low dose gamma radiation on the early growth and resistance to subsequent high dose of radiation. The effect of the low dose gamma radiation on the early growth and resistance to subsequenct high dose of radiation were enhanced in Johong cultivar but not in Jokwang cultivar. Germination rate and early growth of Johong cultivar were noticeably increased at 4 Gy-, 8 Gy- and 20 Gy irradiation group. Resistance to subsequent high dose of radiation of Johong cultivar were increased at almost all of the low dose irradiation group. Especially it was highest at 4 Gy irradiation group. The carotenoid contents and enzyme activity on the resistance to subsequent high dose of radiation of Johong cultivar were increased at the 4 Gy and 8 Gy irradiation group.

A NUMERICAL TREATMENT OF ANISOTROPIC RADIATION FIELDS COUPLED WITH RELATIVISTIC RESISTIVE MAGNETOFLUIDS

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Hiroyuki R. [Center for Computational Astrophysics, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan); Ohsuga, Ken [Division of Theoretical Astronomy, National Astronomical Observatory of Japan, Mitaka, Tokyo 181-8588 (Japan)

2013-08-01

We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 Multiplication-Sign 4 matrices (for the gas-radiation interaction) and 3 Multiplication-Sign 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag.

A NUMERICAL TREATMENT OF ANISOTROPIC RADIATION FIELDS COUPLED WITH RELATIVISTIC RESISTIVE MAGNETOFLUIDS

International Nuclear Information System (INIS)

Takahashi, Hiroyuki R.; Ohsuga, Ken

2013-01-01

We develop a numerical scheme for solving fully special relativistic, resistive radiation magnetohydrodynamics. Our code guarantees conservation of total mass, momentum, and energy. The radiation energy density and the radiation flux are consistently updated using the M-1 closure method, which can resolve an anisotropic radiation field, in contrast to the Eddington approximation, as well as the flux-limited diffusion approximation. For the resistive part, we adopt a simple form of Ohm's law. The advection terms are explicitly solved with an approximate Riemann solver, mainly the Harten-Lax-van Leer scheme; the HLLC and HLLD schemes are also solved for some tests. The source terms, which describe the gas-radiation interaction and the magnetic energy dissipation, are implicitly integrated, relaxing the Courant-Friedrichs-Lewy condition even in an optically thick regime or a large magnetic Reynolds number regime. Although we need to invert 4 × 4 matrices (for the gas-radiation interaction) and 3 × 3 matrices (for the magnetic energy dissipation) at each grid point for implicit integration, they are obtained analytically without preventing massive parallel computing. We show that our code gives reasonable outcomes in numerical tests for ideal magnetohydrodynamics, propagating radiation, and radiation hydrodynamics. We also applied our resistive code to the relativistic Petschek-type magnetic reconnection, revealing the reduction of the reconnection rate via radiation drag

Resistance of Salmonella enteritidis variety typhimurium to gamma radiation

International Nuclear Information System (INIS)

Norberg, A.N.; Maliska, C.

1988-01-01

The use of ionizing radiations to kill microrganisms responsible for food deterioration, and toxinfections is an example of peaceful use of nuclear energy. Food toxinfections are, amongus, produced mostly by Salmonella enteritidis var. typhimurium. Due to the pauncity of information on the resistance to gamma radiation of Salmonella enteritidis var. typhimurium this paper has the aim to define the 60-Cobalt gamma radiation lethal dose to these bacteria, in experimentally contaminated milk by samples recovered from our geographycal area. One hundred nineteen samples of milk containing about 150.000 bacteria per ml were irradiated with doses ranging from 100 to 1.100 Gy. Two samples of surving bacteria were again irradiated by doses up to 2.500 Gy. The bacteria not previously irradiated were killed by doses of 1.100 Gy. It was concluded that the 60-Cobalt gamma radiation minimal lethal dose to Salmonella enteritidis var. typhimurium is 1.200 Gy. The surviving strains to smaller doses than 1.200 Gy when re-irradiated prompt the forthcoming of more radio-resistant germs. (author) [pt

Radiation resistance of InP-related materials

International Nuclear Information System (INIS)

Yamaguchi, Masafumi; Takamoto, Tatsuya; Ikeda, Eiji; Kurita, Hiroshi; Ohmori, Masamichi; Ando, Koshi; Vargas-Aburto, C.

1995-01-01

Irradiation effects of 1-MeV electrons on InP-related materials such as InP, InGaP and InGaAsP have been examined in comparison with those of GaAs. Superior radiation-resistance of InP-related materials and their devices compared to GaAs has been found in terms of minority-carrier diffusion length and properties of devices such as solar cells and light-emitting devices. Moreover, minority-carrier injection-enhanced annealing of radiation-induced defects in InP-related materials has also been observed. (author)

Radiation resistant quench protection diodes for the LHC

International Nuclear Information System (INIS)

Hagedorn, D.; Coull, L.

1994-01-01

The quench protection diodes for the proposed Large Hadron Collider at CERN will be located inside the He-II vessel of the short straight section of one half cell, where they could be exposed to a radiation dose of about 50 kGy and a total neutron fluence of about 10 15 n/cm 2 over 10 years at temperatures of about 2 K. To investigate the influence of irradiation on the electrical characteristics of the diodes, newly developed diodes of thin base region of the diffusion type and of the epitaxial type have been submitted to irradiation tests at liquid nitrogen temperature in a target area of the SPS accelerator at CERN. The degradation of the electrical characteristics of the diodes for a radiation dose up to about 20 kGy and neutron fluence of up to about 5 10 14 n/cm 2 and the effect of carrier injection and thermal annealing after irradiation have been measured. The test results show that only the thin base diodes of the epitaxial type are really radiation resistant. A compromise must be found between required blocking characteristics and radiation resistance. Annealing by carrier injection and occasional warm up to room temperature can extend the service life of irradiated diodes quite substantially

Experiment of radiation-resistant materials for nuclear powers generating station

International Nuclear Information System (INIS)

Choe, J.H.; Lee, C.K.; Kong, Y.K.; Chang, H.S.

1981-01-01

The properties of polyethylene materials exhibit good insulation and radiation resistance, but exhibit poor flame resistance. Flame retardant properties of the polyethylene were improved by the radiation induced grafting, coating or cross-linking. When the various flame retardants were fixed onto polyethylene, the amount of fixation in grafting or coating was increased with the increase of radiation dosages. In the case of grafting, it is necessary for high grafting yield that the polyethylene films were swelled before irradiation with γ-rays or electron beams. It is the suitable method for the fixation of flame retardant that polyethylene samples were blended with various flame retardants at 125 0 C and then blended polymers were crosslinked by the electron beams at room temperature

Radiation resisting features of pure quartz fiber

International Nuclear Information System (INIS)

Fujii, Takashi; Nagasawa, Yoshiya; Hoshi, Hiroshi; Tomon, Ryoichi; Ooki, Yoshimichi; Yahagi, Kichinosuke

1985-01-01

The control of the generation of color centers is essential for optical fibers used in radiation environment. Even pure quartz which is the best radiation resisting material is not exceptional also elucidarion of the mechanism of the generation of color center is necessary for the development of optical fiber with higher radiation resisting feature. Previously, it was assumed that color centers are distributed uniformly throughout cores. Determination of the distribution of color centers was attempted. Cores were etched with HF after γ-ray irradiation, and the changes of intensity of ESR signals of NBOHC and E'-center were determined. NBOHC were not found in circumferential part, and concentrated in the central part. In other words the tendency of distribution is diametral. Thus, the distribution of precursor is supposed to be affected by certain external cause and the generation of NBOHC was depressed in circumferential area. The distribution of E'-center of high OH sample showed similar tendency and high in the center. Where as the distribution in low OH sample was uniform. The external cause is supposed to be hydrogen derived from silicone clad and silicone buffer. Two kind of precursor is suspected for the explanation of the difference of the E'-center in high OH sample and low OH sample. (Ishimitsu, A.)

Heat- and radiation-resistant scintillator for electron microscopes

International Nuclear Information System (INIS)

Kosov, A.V.; Petrov, S.A.; Puzyr', A.P.; Chetvergov, N.A.

1987-01-01

The use of a scintillator consisting of a single crystal of bismuth orthogermanate, which has high heat and radiation resistance, in REM-100, REM-200, and REM-100U electron microscopes is described. A study of the heat and radiation stabilities of single crystals of bismuth orthogermanate (Bi 4 Ge 3 O 12 ) has shown that they withstood multiple electron-beam heating redness (T ∼ 800 0 C) without changes in their properties

A study on measurement of radiation resistance of Pyronema domesticum sclerotia

International Nuclear Information System (INIS)

Aoshuang, Y.; Ailian, W.; Ying, Z.

2000-01-01

Measurements of radiation resistance have been carried out using two strains of Pyronema domesticum which were isolated from Chinese cotton swab gauze. A 'sand-washing' technique was developed to overcome the difficulties when harvesting sclerotia spores from cultured plates and preparing spore suspensions for further use. Three types of microbial preparations, spore suspension, inoculated cotton and spore dot, were exposed to gamma radiation. A dose-survival curve method and a fraction positive method were employed to determine radiation resistance. D 10 values derived from this study are within the range of 2.0-3.0 kGy. Concerns associated with the current study indicate that further work is needed. (author)

Some physiological and morphological aspects of radiation-resistant bacteria and a new method for their isolation from food

International Nuclear Information System (INIS)

Sanders, S.W.

1978-01-01

A study was undertaken to help clarify the taxonomic positions and mechanisms of radiation resistance of radiation-resistant asporogenous bacteria found in foods. Determinations of DNA base compositions of highly resistant Moroxella-Acinetobacter (M-A) strains indicated that they were atypical, having percent guanine plus cytosine contents exceeding the values for true Moraxella or Acinetobacter spp. By direct observation of dividing cells, the resistant M-A were found to undergo multiple-plane division. Electron micrographs revealed unusually thick cell walls in the M-A as compared with gram-negative bacteria, indicating a possible role of the cell wall in radiation resistance. Resistance to desiccation was utilized in the selection of highly radiation-resistant bacteria from non-irradiated sources. Bacteria from a food or other source were suspended in dilute phosphate buffer and dried in a thin film at 25 C and 33% relative humidity. Storage under these conditions for 15 days or more reduced the numbers of radiation-sensitive bacteria. Further selection of the most radiation-resistant bacteria was obtained by irradiation of bacteria on velveteen in the replication process, thereby allowing the isolation of highly resistant bacteria that had not been irradiated. The similarity of radiation-resistance and identifying characteristics between irradiated and non-irradiated isolates indicated that highly radiation-resistant bacteria are not altered by radiation selection. Irradiated Plate Count Agar and Tryptic Soy Agar were found to be very toxic to radiation-resistant bacteria. This phenomenon may be important in food irradiation, where the ability to survive and grow in a product may depend partly on the sensitivity to bacteriocidal products formed during irradiation

Resistance to BN myelogenous leukemia in rat radiation chimeras

International Nuclear Information System (INIS)

Singer, D.E.; Haynor, D.R.; Williams, R.M

1980-01-01

Lewis → LBNFl rat radiation chimeras showed marked resistance to transplanted BN myelogenous leukemia when compared to naive LBNFl, LBNFl → LBNFl, or BN → LBNFl. This occurred in the absence of overt graft versus host disease or of anti-BN response in mixed lymphocyte culture. Bone marrow specific antigens may serve as the target of the resistance mechanism. (author)

Shielding ability of lead loaded radiation resistant gloves

International Nuclear Information System (INIS)

Kawano, Takao; Ebihara, Hiroshi

1990-01-01

The shielding ability of radiation resistant gloves were examined. The gloves are made of lead loaded (as PbO 2 ) polyvinyl chloride resin and are about 0.4 mm of thickness (70 mg/cm 2 ). Eleven test pieces were sampled from each of three gloves (total were thirty three) and the transmission rates for radiations (X-ray or γ-ray) through the test pieces were measured with radiation sources, 99m Tc, 57 Co, 133 Ba, 133 Xe and 241 Am. The differences of the transmission rate for radiations by the positions of the gloves were smaller than 15%, and the differences by three gloves were smaller than 5% in the case of 60 keV and 141 keV radiations. The average transmission rates for radiations in thirty three test pieces were about 40% for 30 keV radiation, about 90% for 80 keV and 140 keV radiations. The shielding characteristic of the gloves could be equivalent to about 0.026 mm thick lead plate. (author)

Radiation-resistant optical sensors and cameras; Strahlungsresistente optische Sensoren und Kameras

Energy Technology Data Exchange (ETDEWEB)

Fischer, G. [Imaging and Sensing Technology, Bonn (Germany)

2008-02-15

Introducing video technology, i.e. 'TV', specifically in the nuclear field was considered at an early stage. Possibilities to view spaces in nuclear facilities by means of radiation-resistant optical sensors or cameras are presented. These systems are to enable operators to monitor and control visually the processes occurring within such spaces. Camera systems are used, e.g., for remote surveillance of critical components in nuclear power plants and nuclear facilities, and thus contribute also to plant safety. A different application of optical systems resistant to radiation is in the visual inspection of, e.g., reactor pressure vessels and in tracing small parts inside a reactor. Camera systems are also employed in remote disassembly of radioactively contaminated old plants. Unfortunately, the niche market of radiation-resistant camera systems hardly gives rise to the expectation of research funds becoming available for the development of new radiation-resistant optical systems for picture taking and viewing. Current efforts are devoted mainly to improvements of image evaluation and image quality. Other items on the agendas of manufacturers are the reduction in camera size, which is limited by the size of picture tubes, and the increased use of commercial CCD cameras together with adequate shieldings or improved lenses. Consideration is also being given to the use of periphery equipment and to data transmission by LAN, WAN, or Internet links to remote locations. (orig.)

Radiation resistance of pyrocarbon-boned fuel and absorbing elements for HTGR

International Nuclear Information System (INIS)

Gurin, V.A.; Konotop, Yu.F.; Odejchuk, N.P.; Shirochenkov, S.D.; Yakovlev, V.K.; Aksenov, N.A.; Kuprienko, V.A.; Lebedev, I.G.; Samsonov, B.V.

1990-01-01

In choosing the reactor type, problems of nuclear and radiation safety are outstanding. The analysis of the design and experiments show that HTGR type reactors helium cooled satisfy all the safety requirements. It has been planned in the Soviet Union to construct two HTGR plants, VGR-50 and VG-400. Later it was decided to construct an experimental plant with a low power high temperature reactor (VGM). Spherical uranium-graphite fuel elements with coated fuel particles are supposed to be used in HTGR core. A unique technology for producing spherical pyrocarbon-bound fuel and absorbing elements of monolithic type has been developed. Extended tests were done to to investigate fuel elements behaviour: radiation resistance of coated fuel particles with different types of fuel; influence of the coated fuel particles design on gaseous fission products release; influence of non-sphericity on coated fuel particle performance; dependence of gaseous fission products release from fuel elements on the thickness of fuel-free cans; confining role of pyrocarbon as a factor capable of diminishing the rate of fission products release; radiation resistance of spherical fuel elements during burnup; radiation resistance of spherical absorbing elements to fast neutron fluence and boron burnup

Radiation resistance of insulating materials for electric wires

International Nuclear Information System (INIS)

Kanemitsuya, Kazuhiko; Okuda, Tomoaki; Tachibana, Tadao; Yagi, Toshiaki; Seguchi, Tadao.

1990-01-01

In no halogen incombustible materials, smoke and poisonous gas generation at the time of burning is small, and corrosive gas rarely arises. Since no halogen electric wires and cables which use these material maintain safety for people and equipment in the case of fires, those are used for ships, tunnels, subways and so on. Also in nuclear power stations, the demand for no halogen cables becomes high although the condition of adoption is difficult. In this study, for the purpose of developing the no halogen cables for nuclear power stations, the basic data on the radiation resistance of no halogen incombustible materials were collected, and by using chemical analysis method, the radiation deterioration behavior was examined. The samples were those with base polymers of VLDPE, ULDPE, EEA, EMA and EVA. Gamma ray irradiation, tensile test, chemi-luminescence measurement, and the determination of gel fraction and swelling rate were carried out. The results are reported, In no halogen materials, when ethylene system copolymer is used as the base polymer instead of PE, the composition with good radiation resistance can be obtained, and by combining amine oxidation inhibitor, it is further improved. (K.I.)

Genetic analysis of resistance to radiation lymphomagenesis with recombinant inbred strains of mice

International Nuclear Information System (INIS)

Okumoto, M.; Nishikawa, R.; Imai, S.; Hilgers, J.

1990-01-01

Induction of lymphomas by radiation in mice is controlled by genetic factors. We analyzed the genetic control of radiation lymphomagenesis using the CXS series of recombinant inbred strains derived from two progenitor strains: one highly susceptible to radiation induction of lymphoma [BALB/cHeA (C)] and one extremely resistant [STS/A (S)]. The best concordances between strain distribution patterns of genetic markers and resistance (or susceptibility) to radiation lymphomagenesis were observed in a region with the b and Ifa genes on chromosome 4. This indicates that one major locus controls the incidence of radiogenic lymphomas in mice. We designated this locus as the Lyr (lymphoma resistance) locus. Backcrosses of (CXS)F1 to the two progenitor strains showed an intermediate incidence of lymphomas between their parental mice and did not significantly differ from (CXS)F1 mice. This and previous observations that (CXS)F1 mice also showed an intermediate incidence, differing from both progenitor strains, indicate that more genes are involved in the resistance (or susceptibility) to lymphoma induced by irradiation

Flame-Resistant Composite Materials For Structural Members

Science.gov (United States)

Spears, Richard K.

1995-01-01

Matrix-fiber composite materials developed for structural members occasionally exposed to hot, corrosive gases. Integral ceramic fabric surface layer essential for resistance to flames and chemicals. Endures high temperature, impedes flame from penetrating to interior, inhibits diffusion of oxygen to interior where it degrades matrix resin, resists attack by chemicals, helps resist erosion, and provides additional strength. In original intended application, composite members replace steel structural members of rocket-launching structures that deteriorate under combined influences of atmosphere, spilled propellants, and rocket exhaust. Composites also attractive for other applications in which corrosion- and fire-resistant structural members needed.

Radiation resistance of the carbon fiber reinforced composite material with PEEK as the matrix resin

International Nuclear Information System (INIS)

Sasuga, Tsuneo; Seguchi, Tadao; Sakai, Hideo; Nakakura, Toshiyuki; Masutani, Masahiro.

1987-01-01

In the fast breeder reactor etc. the structural materials are exposed to various environment, i.e., repeated high and low temperature, stress, etc. Irradiation effect (electron radiation) in the mechanical characteristic at low and high temperature has been studied in the PEEK-CF, polyarylether · ether · ketone - carbon fiber composite. Following are the results. (1) Radiation resistance of PEEK-CF is higher than that of PEEK-PES-CF, PEEK - polyethersulfone surface treated CF composite. In PEEK-PES-CF, PES is deteriorated by irradiation so the adhesive power lowers. (2) In the unirradiated PEEK-CF, its mechanical characteristic decreases beyond 140 deg C. With increase of the radiation dose, however, the characteristic rises. (3) Mechanical characteristic of PEEK-CF thus little drops by the heat treatment after the irradiation. (Mori, K.)

Radiation response of drug-resistant variants of a human breast cancer cell line

International Nuclear Information System (INIS)

Lehnert, S.; Greene, D.; Batist, G.

1989-01-01

The radiation response of drug-resistant variants of the human tumor breast cancer cell line MCF-7 has been investigated. Two sublines, one resistant to adriamycin (ADRR) and the other to melphalan (MLNR), have been selected by exposure to stepwise increasing concentrations of the respective drugs. ADRR cells are 200-fold resistant to adriamycin and cross-resistant to a number of other drugs and are characterized by the presence of elevated levels of selenium-dependent glutathione peroxidase and glutathione-S-transferase. MLNR cells are fourfold resistant to melphalan and cross-resistant to some other drugs. The only mechanism of drug resistance established for MLNR cells to date is an enhancement of DNA excision repair processes. While the spectrum of drug resistance and the underlying mechanisms differ for the two sublines, their response to radiation is qualitatively similar. Radiation survival curves for ADRR and MLNR cells differ from that for wild-type cells in a complex manner with, for the linear-quadratic model, a decrease in the size of alpha and an increase in the size of beta. There is a concomitant decrease in the size of the alpha/beta ratio which is greater for ADRR cells than for MLNR cells. Analysis of results using the multitarget model gave values of D0 of 1.48, 1.43, and 1.67 Gy for MCF-7 cells are not a consequence of cell kinetic differences between these sublines. Results of split-dose experiments indicated that for both drug-resistant sublines the extent of sublethal damage repair reflected the width of the shoulder on the single-dose survival curve. For MCF-7 cells in the stationary phase of growth, the drug-resistant sublines did not show cross-resistance to radiation; however, delayed subculture following irradiation of stationary-phase cultures increased survival to a greater extent for ADRR and MLNR cells than for wild-type cells

CERTIFICATION OF THE RADIATION RESISTANCE OF COIL INSULATION MATERIAL

CERN Document Server

Polinski, J; Bogdan, P

2013-01-01

The goal of the WP 7.2.1 sub-task of the EuCARD program has been to determine the Nb$_{3}$Sn based accelerator magnet coil electrical insulation resistance against irradiation, which will occur in future accelerators. The scope of the certification covers determination of mechanical, electrical and thermal properties changes due to irradiation. The report presents a selection of the insulation material candidates for future accelerator magnets as well as the definition of the radiation certification methodology with respect of radiation type, energy, doses and irradiation conditions. The test methods and results of the electrical and mechanical insulation materials properties degradation due to irradiation are presented. Thermal conductivity and Kapitza resistance at temperature range from 1.5 K to 2.0 K (superfluid helium conditions) are given.

Induced resistance to hydrogen peroxide, UV and gamma radiation in bacillus species

International Nuclear Information System (INIS)

Bashandy, A.S.

2005-01-01

The catalase activity produced in four bacillus spp.(bacillus cereus, B. laterosporus, B. pumilus and B. subtilis (Escherichia coli was used for comparison) was measured and the sensitivity of these bacteria to hydrogen peroxide was tested. Bacillus spp. had higher resistance to hydrogen peroxide than E. coil. cultures of bacillus spp . When pretreated with sublethal level of hydrogen peroxide, became relatively resistant to the lethal effects of hydrogen than untreated control cultures. These pretreated cells were also resistant to lethality mediated by UV light and gamma radiation. The obtained results suggest that bacillus spp. Possess inducible defense mechanism (s) against the deleterious effects of oxidants and /or ionizing radiation

Resistance of CFRP structures to environmental degradation in low Earth orbit

Science.gov (United States)

Suliga, Agnieszka

Within this study, a development of a protection strategy for ultra-thin CFRP structures from degrading effects of low Earth orbit (LEO) is presented. The proposed strategy involves an application of a modified epoxy resin system on outer layers of the structure, which is cycloaliphatic in its chemical character and reinforced with POSS nanoparticles. The core of the CFRP structure is manufactured using a highly aromatic epoxy resin system which provides excellent mechanical properties, however, its long-term ageing performance in space is not satisfactory, and hence a surface treatment is required to improve its longevity. The developed resin system presented in this thesis is a hybrid material, designed in such a way that its individual constituents each contribute to combating the detrimental effects of radiation, atomic oxygen (AO), temperature extremes and vacuum induced outgassing of exposed material surfaces while operating in LEO. The cycloaliphatic nature of the outer epoxy increases UV resistance and the embedded silicon nanoparticles improve AO and thermal stability. During the study, a material characterization of the developed cycloaliphatic epoxy resins was performed including the effects of nanoparticles on morphology, curing behaviour, thermal-mechanical properties and surface chemistry. Following on that, the efficacy of the modified resin system on space-like resistance was studied. It was found that when the ultra-thin CFRP structures are covered with the developed resin system, their AO resistance is approximately doubled, UV susceptibility decreased by 80% and thermal stability improved by 20%. Following on the successful launch of the InflateSail mission earlier this year, which demonstrated a sail deployment and a controlled de-orbiting, the findings of this study are of importance for the future generation of similar, but significantly longer missions. Ensuring resistance of CFRP structures in a highly corrosive LEO environment is a critical

Correlation of electromagnetic radiation emitted from coal or rock to supporting resistance

Energy Technology Data Exchange (ETDEWEB)

Jia, Hui-lin; Wang, En-yuan; Song, Xiao-yan; Zhang, Hong-jie; Li, Zhong-hui [China University of Mining & Technology, Xuzhou (China). School of Safety Engineering

2009-05-15

More accurate forecasting of rock burst might be possible from observations of electromagnetic radiation emitted in the mine. We analyzed experimental observations and field data from the Muchengjian coal mine to study the relationship between electromagnetic radiation signal intensity and stress during the fracturing of coal, or rock, and samples under load. The results show that the signal intensity is positively correlated with stress. In addition, we investigated the change in the electromagnetic radiation intensity, the supporting resistance in a real coal mine environment, and the coal or rock stress in the mining area. The data analysis indicates that: (1) electromagnetic radiation intensity can accurately reflect the distribution of stress in the mining area; and, (2) there is a correlation between electromagnetic radiation intensity and supporting resistance. The research has some practical guiding significance for rock burst forecasting and for the prevention of accidents in coal mines. 9 refs., 6 figs.

Radiation resistance of polymer materials. Degradation evaluation by accelerated testing for application condition

International Nuclear Information System (INIS)

Seguchi, Tadao; Tamura, Kiyotoshi; Sorimachi, Masami

2010-02-01

This paper presents re-evaluated radiation resistance property data of polymer materials, which had been tested in past times in TAKASAKI Quantum Beam Science Directorate, for the future study of ageing evaluation of low voltage electric cable insulation materials used in light-water nuclear reactors. The radiation resistance of 25 types of plastics and rubbers materials applied in practical environments was evaluated by the accelerated testing of gamma-ray irradiation under oxygen pressure, and was compared with the radiation resistance determined from the traditional testing by irradiation with a high dose rate in air. The polymer materials were formulated to be similar or equivalent to practical materials, and the most of formulation (chemical compounds and quantities) were described. For all materials, the tensile properties (elongation at break, ultimate strength, 100% or 200% modulus), electric resistivity, gel-fraction, and density were measured after irradiation in oxidation conditions and irradiation in air with a high dose rate (non-oxidation conditions). The data of relations between each properties and total dose at various conditions were compiled, and the relations among the changes of mechanical properties, electrical properties, and radiation induced chemical reactions were discussed. (author)

UV light-induced survival response in a highly radiation-resistant isolate of the Moraxella-acinetobacter group

International Nuclear Information System (INIS)

Keller, L.C.; Thompson, T.L.; Maxcy, R.B.

1982-01-01

A highly radiation-resistant member of the Moraxella-Acinetobacter group, isolate 4, obtained from meat, was studied to determine the effect of preexposure to UV radiation on subsequent UV light resistance. Cultures that were preexposed to UV light and incubated for a short time in plate count broth exhibited increased survival of a UV light challenge dose. This response was inhibited in the presence of chloramphenicol. Frequencies of mutation to streptomycin, trimethoprim, and sulfanilamide resistance remained the same after the induction of this survival response and were not altered by treatment with mutagens, with the exception of mutation to streptomycin resistance after γ-irradiation or nitrosoguanidine or methyl methane sulfonate treatment. The results indicated that isolate 4 has a UV light-inducible UV light resistance mechanism which is not associated with increased mutagenesis. The characteristics of the radiation resistance response in this organism are similar to those of certain other common food contaminants. Therefore, considered as part of the total microflora of meat, isolate 4 and the other radiation-resistant Moraxella-Acinetobacter isolates should not pose unique problems in a proposed radappertizaton process

Heat-shock induction of ionizing radiation resistance in Saccharomyces cerevisiae, and the correlation with stationary growth phase

International Nuclear Information System (INIS)

Mitchel, R.E.J.; Morrison, D.P.

1982-01-01

Radiation resistance and thermal resistance vary as a function of culture temperature in logarithmically growing Saccharomyces cerevisiae and are related to the optimum temperature for growth. Radiation resistance and thermal resistance were also induced when cells grown at low temperatures were subjected to a heat shock at or above the optimum growth temperature. Exposure to ionizing radiation followed by a short incubation at low temperature also induced resistance to killing by heat. Heat-shocked cells are induced to a level of thermal and radioresistance much greater than the characteristic resistance level of cells grown continuously at the shock temperature. This high level of resistance, which resembles that of stationary-phase cells, decays to the characteristic log-phase level within one doubling of cell number after the heat shock. Both induction of resistance and decay of that induction require protein synthesis. It is postulated that induction of resistance by heat shock or ionizing radiation is a response of the cells to stress and represents a preparation to enter stationary phase

Radiation resistivity of frozen insulin solutions and suspensions

Energy Technology Data Exchange (ETDEWEB)

Soboleva, N N; Ivanova, A I; Talrose, V L; Trofimov, V I; Fedotov, V P [AN SSSR, Moscow. Inst. Fizicheskoj Khimii; Research Institute for Biological Testing of Chemicals, Moscow (USSR); Institute of Experimental Endocrinology and Hormon Chemistry, Moscow (USSR))

1981-10-01

The effect of great increase in radiation resistance of insulin solutions and suspensions after irradiation at low temperatures in the frozen state was observed by absorption spectrophotometry, paper chromatography and biological analysis. The data obtained suggest irradiation of frozen insulin solutions and suspensions as a method for its sterilization.

Radiation resistance in a melphalan-resistant subline of a rat mammary carcinoma

International Nuclear Information System (INIS)

Lehnert, S.; Vestergaard, J.; Batist, G.; Aloui-Jamali, M.A.

1994-01-01

A subline of a rat mammary carcinoma (MATB 13762), selected for resistance to melphalan, is cross-resistant to other alkylating drugs, to unrelated drugs and to ionizing radiation. The difference in radioresponse between the sensitive wild-type cell line and the melphalan- and radiation-resistant line (MLN r ) is related to the size of the α component in the linear-quadratic model. Reduction of dose rate does not affect the response of MLN r cells but does increase survival for wild-type cells. MLN r cells have elevated levels of reduced glutathione (GSH) and overexpress redox enzymes glutathione-S-transferase and glutathione peroxidase. Modest depletion of GSH (to 50% of control) radiosensitizes MLN r cells but not wild-type cells. On the basis of the results of an excitation assay, growth delay and tumor control experiments, MATB MLN r tumors are also more radioresistant than wild-type cells when irradiated in situ. However, wild-type cells irradiated shortly after excision of the tumor are much more radioresistant than the same cells irradiated 24 h after excision or maintained in culture, and their response resembles that of MLN r cells irradiated under the same conditions. These results suggest that, in spite of some similarity between the in vivo and in vitro observations, intrinsic radioresistance is not the most important factor influencing the response of MLN r cells in vivo. 22 refs., 7 figs., 4 tabs

Radiation damage of silicon structures with electrons of 900 MeV

CERN Document Server

Rachevskaia, I; Bosisio, L; Dittongo, S; Quai, E; Rizzo, G

2002-01-01

We present first results on the irradiation of double-sided silicon microstrip detectors and test structures performed at the Elettra synchrotron radiation facility at Trieste, Italy. The devices were irradiated with 900 MeV electrons. The test structures we used for studying bulk, surface and oxide irradiation damage were guard ring diodes, gated diodes and MOS capacitors. The test structures and the double-sided microstrip detectors were produced by Micron Semiconductor Ltd. (England) and IRST (Trento, Italy). For the first time, bulk-type inversion is observed to occur after high-energy electron irradiation. Current and inter-strip resistance measurements performed on the microstrip detectors show that the devices are still usable after type inversion.

Radiation performance of AlGaAs concentrator cells and expected performance of cascade structures

International Nuclear Information System (INIS)

Curtis, H.B.; Swartz, C.K.; Hart, R.E. Jr.

1987-01-01

Aluminum gallium arsenide, GaAs, silicon and InGaAs cells have been irradiated with 1 MeV electrons and 37 MeV protons. These cells are candidates for individual cells in a cascade structure. Data is presented for both electron and proton irradiation studies for one sun and a concentration level of 100X AMO. Results of calculations on the radiation resistance of cascade cell structures based on the individual cell data are also presented. Both series connected and separately connected structures are investigated

Development of new radiation resistant, fire-retardant cables

International Nuclear Information System (INIS)

Hagiwara, Ko; Morita, Yosuke; Udagawa, Takashi; Fujimura, Shun-ichi; Oda, Eisuke.

1982-01-01

For the cables for nuclear facilities, radiation resistance and fire-retardation are severely required. The authors took note of the fact that even in the existing cables for nuclear power plants, their mechanical properties are greatly degraded by the exposure to large dose (for example, 200 Mrad in PWR testing conditions), and attempted the improvement. They employed a new additive, bromated acenaphthylene condensate (con-BACN), which effectively gives radiation resistance and also is a good flame retarder, to be compounded to an insulation material, and examined the characteristics. In this paper, the features of con-BACN and the investigation of fire-retardant EPDM composition are described. As an initial composition, a small amount of zinc white, sulphur, stearic acid, noclac 224 (Ouchi-Shinko Chemicals, Co.), and antimony trioxide, 100 parts of tale and 45 parts of con-BACN were added to 100 parts of EPDM (propylene content 34 %, Japan Synthetic Rubber Co.). As the antiaging agent, it was decided to use phenol series No. 3 as a result of test. The fire-retardant EP rubber-composed cable was produced for trial, its insulation being fabricated, using a Furukawa's pressurized salt bath continuous vulcanizer. The tests of γ-irradiation, simulated LOCA and combustion were carried out, and the test results are reported. It was indicated that the cable resisted against high dose several times as much as 200 Mrad, and was suitable for the applications, in which the mechanical properties such as bending are required to be maintained after radiation exposure. It was also found that con-BACN was safe, and its properties of decomposition, concentration and acute toxicity were all very low. (Wakatsuki, Y.)

Radiation Effects on Spacecraft Structural Materials

International Nuclear Information System (INIS)

Wang, Jy-An J.; Ellis, Ronald J.; Hunter, Hamilton T.; Singleterry, Robert C. Jr.

2002-01-01

Research is being conducted to develop an integrated technology for the prediction of aging behavior for space structural materials during service. This research will utilize state-of-the-art radiation experimental apparatus and analysis, updated codes and databases, and integrated mechanical and radiation testing techniques to investigate the suitability of numerous current and potential spacecraft structural materials. Also included are the effects on structural materials in surface modules and planetary landing craft, with or without fission power supplies. Spacecraft structural materials would also be in hostile radiation environments on the surface of the moon and planets without appreciable atmospheres and moons around planets with large intense magnetic and radiation fields (such as the Jovian moons). The effects of extreme temperature cycles in such locations compounds the effects of radiation on structural materials. This paper describes the integrated methodology in detail and shows that it will provide a significant technological advance for designing advanced spacecraft. This methodology will also allow for the development of advanced spacecraft materials through the understanding of the underlying mechanisms of material degradation in the space radiation environment. Thus, this technology holds a promise for revolutionary advances in material damage prediction and protection of space structural components as, for example, in the development of guidelines for managing surveillance programs regarding the integrity of spacecraft components, and the safety of the aging spacecraft. (authors)

Role of manganese in the resistance of Micrococcus radiodurans to ionizing radiation

International Nuclear Information System (INIS)

Wierowski, J.V.

1980-01-01

Micrococcus radiodurans possesses a very high level of intracellular manganese compared to other organisms. This manganese content has previously been shown to participate in the exceptional ulraviolet radiation resistance of M. radiodurans. This study was undertaken to determine the role of manganese in the ionizing radiation resistant of M. radiodurans. The results indicate that manganese is essential for DNA degradation to occur during irradiation. Manganese has also proven essential for the second phase of post-irradiation thymine base damage removal. These factors work together to increase the rate of recovery from radiation damage, which is reflected in a larger Dq, D 37 and exponential portion of the survival curve of high Mn-grown cells

INFLUENCE OF INCUBATION TIME, GAMMA RAYS AND ELECTRON BEAM ON RADIATION RESISTANCE OF SOME SELECTED PATHOGENS

International Nuclear Information System (INIS)

EL-HIFNAWI, H.N.; EL-TABLAWY, S.Y.

2009-01-01

The effect of different growth phases on the radiation resistance, antibiotic susceptibility and pathogenicity of certain selected pathogens (Escherichia coli, Candida albicans and Staphylococcus aureus) was studied in mice. The obtained results showed that Escherichia coli was slightly more resistant to gamma radiation in 18 h than 24 h or 48 h but it was relatively more resistant to electron beam in 24 h and 48 h than 18 h. Candida albicans showed radiation resistance nearly the same in all incubation times in the case of gamma radiation while for electron beam, its radiation resistance was slightly more in 24 h and 48 h than in 18 h. On the other hand, Staphylococcus aureus recorded much more resistance to gamma radiation in the 48 h than in 24 h or 18 h whereas in the case of electron beam, it was slightly more resistant in 18 h than in 24 h and 48 h.The antibiotic susceptibility of Escherichia coli reported that the exposure to gamma radiation at 3 kGy and electron beam at 6 kGy increase the susceptibility to the nalidixic acid and nitrofurantoin. When Candida albicans was exposed to 3 kGy gamma radiation and 6 kGy electron beam, the same sensitivity to nystatin was observed in comparison with the unexposed one while the sensitivity of Staphylococcus aureus to some antibiotics (amoxicillin, nitrofurantoin and tetracycline) was decreased after exposure to gamma radiation at 0.75 and 2 kGy and electron beam at 6 kGy, but for other antibiotics (trimethoprim/ sulfamethoxazole), the sensitivity was increased at 6 kGy electron beam.The lethality percent recorded after the oral ingestion of the mice with the unexposed Escherichia coli and Candida albicans were 25% and 100%, respectively, and for 6 kGy exposure to electron beam was 0% . The cotaneous disease and abscesses caused by the intradermal injection of the mice with unexposed Staphylococcus aureus was 75% and for 6 kGy exposure to electron beam was 25%.

Irradiation test of component for radiation-resistant small sized motor

International Nuclear Information System (INIS)

Nakamichi, M.; Ishitsuka, E.; Shimakawa, S.; Kan, S.

2009-01-01

A small-sized motor with a resistance to radiation was developed. This motor has been able to operate at a gamma-ray dose of a value 700 times as high as the specification of a commercial motor. The present work describes results of post-irradiation examinations (PIEs) to evaluate effects of neutron irradiation on the lifetime of some major components of the motor such as a bearing, a magnet and a fixation agent for a field coil wire. It became clear from the results of PIEs that the radiation-resistance dose of the motor using a Sm-Co magnet will be expected to be one order of magnitude higher than that of the motor using a Nb-Fe-B magnet.

Studies on the flame and radiation resistant modification of wires and cables for nuclear power generation plants

International Nuclear Information System (INIS)

Hagiwara, Miyuki; Morita, Yosuke; Udagawa, Akira; Oda, Eisuke; Fujimura, Shunichi.

1982-08-01

For the use in the light-water nuclear power generation plants, wires and cables are required to keep high flame retardancy and superior resistivity against heat and radiation throughout the whole period of service. They are expected, further, to fulfill their functions even under LOCA conditions. The present work aimed to provide new technology to give flame and radiation resistancy to insulating materials for the cables which are used under the above requirements. For the improvement of flame retardancy and the elongation of life time, polymerizable flame retardants were examined their applicability to ethylene-propylene-diene rubber. Various polymerizable flame retardants were first synthesized, and their performance was analyzed, especially, as to the relationship between molecular structure and their effectiveness. As a guiding principle for developing of a high performance flame and radiation resistant reagent, it was suggested that the back born of the reagent molecule should be constructed by carbon-carbon bond including fused aromatic rings and groups which can undergo polymerization by radical initiators. After careful consideration and detailed experimental work, condensed bromoacenaphthylene (con-BACN) was shown to have an effectiveness enough for the present purpose. Its satisfactory performance was also shown by making cables of a practical size using con-BACN, and by carrying out various performance tests based substantially on IEEE standards. (author)

SU-C-303-01: Activation-Induced Cytidine Deaminase Confers Cancer Resistance to Radiation Therapy

International Nuclear Information System (INIS)

Yi, S; La Count, S; Liu, J; Bai, X; Lu, L

2015-01-01

Purpose: To study the role of activation-induced cytidine deaminase (AID) in malignant cell resistance to radiation therapy. Methods: We first developed several small devices that could be used to adopt radiation beams from clinical high dose rate brachy therapy (HDR) or linac-based megavoltage machines to perform pre-clinical cell and mouse experiments. Then we used these devices to deliver radiation to AID-positive and AID-silenced cancer cells or tumors formed by these cells in mice. Cells and mice bearing tumors received the same dose under the same experimental conditions. For cells, we observed the apoptosis and the cell survival rate over time. For mice bearing tumors, we measured and recorded the tumor sizes every other day for 4 weeks. Results: For cell experiments, we found that the AID-positive cells underwent much less apoptosis compared with AID-silenced cells upon radiation. And for mouse experiments, we found that AID-positive tumors grew significantly faster than the AID-silenced tumors despite of receiving the same doses of radiation. Conclusion: Our study suggests that AID may confer cancer resistance to radiation therapy, and AID may be a significant biomarker predicting cancer resistance to radiation therapy for certain cancer types

Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

Energy Technology Data Exchange (ETDEWEB)

Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2014-05-15

Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest.

Study on the Hot Extrusion Process of Advanced Radiation Resistant Oxide Dispersion Strengthened Steel Tubes

International Nuclear Information System (INIS)

Choi, Byoungkwon; Noh, Sanghoon; Kim, Kibaik; Kang, Suk Hoon; Chun, Youngbum; Kim, Tae Kyu

2014-01-01

Ferritic/martensitic steel has a better thermal conductivity and swelling resistance than austenitic stainless steel. Unfortunately, the available temperature range of ferritic/martensitic steel is limited at up to 650 .deg. C. Oxide dispersion strengthened (ODS) steels have been developed as the most prospective core structural materials for next generation nuclear systems because of their excellent high strength and irradiation resistance. The material performances of this new alloy are attributed to the existence of uniformly distributed nano-oxide particles with a high density, which is extremely stable at high temperature in a ferritic/martensitic matrix. This microstructure can be very attractive in achieving superior mechanical properties at high temperatures, and thus, these favorable microstructures should be obtained through the controls of the fabrication process parameters during the mechanical alloying and hot consolidation procedures. In this study, a hot extrusion process for advanced radiation resistant ODS steel tube was investigated. ODS martensitic steel was designed to have high homogeneity, productivity, and reproducibility. Mechanical alloying and hot consolidation processes were employed to fabricate the ODS steels. A microstructure observation and creep rupture test were examined to investigate the effects of the optimized fabrication conditions. Advanced radiation resistant ODS steel has been designed to have homogeneity, productivity, and reproducibility. For these characteristics, modified mechanical alloying and hot consolidation processes were developed. Microstructure observation revealed that the ODS steel has uniformly distributed fine-grain nano-oxide particles. The fabrication process for the tubing is also being propelled in earnest

High resistance of some oligotrophic bacteria to ionizing radiation

International Nuclear Information System (INIS)

Nikitin, D.I.; Tashtemirova, M.A.; Pitryuk, I.A.; Sorokin, V.V.; Oranskaya, M.S.; Nikitin, L.E.

1994-01-01

The resistance of seven cultures of eutrophic and oligotrophic bacteria to gamma radiation (at doses up to 360 Gy) was investigated. The bacteria under study were divided into three groups according to their survival ability after irradiation. Methylobacterium organophilum and open-quotes Pedodermatophilus halotoleransclose quotes (LD 50 = 270 Gy) were highly tolerant. By their tolerance, these organisms approached Deinococcus radiodurans. Aquatic ring-shaped (toroidal) bacteria Flectobacillus major and open-quotes Arcocella aquaticaclose quotes (LD 5 = 173 and 210 Gy, respectively) were moderately tolerant. Eutrophic Pseudomonas fluorescens and Escherichia coli (LD 50 = 43 and 38 Gy, respectively) were the most sensitive. X-ray microanalysis showed that in tolerant bacteria the intracellular content of potassium increased and the content of calcium decreased after irradiation. No changes in the element composition of the eutrophic bacterium E. coli were detected. Possible mechanisms of the resistance of oligotrophic bacteria to gamma radiation are discussed

Electromagnetic Radiation of Electrons in Periodic Structures

CERN Document Server

Potylitsyn, Alexander Petrovich

2011-01-01

Periodic magnetic structures (undulators) are widely used in accelerators to generate monochromatic undulator radiation (UR) in the range from far infrared to the hard X-ray region. Another periodic crystalline structure is used to produce quasimonochromatic polarized photon beams via the coherent bremsstrahlung mechanism (CBS). Due to such characteristics as monochromaticity, polarization and adjustability, these types of radiation is of large interest for applied and basic research of accelerator-emitted radiation. The book provides a detailed overview of the fundamental principles behind electromagnetic radiation emitted from accelerated charged particles (e.g. UR, CBS, radiation of fast electrons in Laser flash fields) as well as a unified description of relatively new radiation mechanisms which attracted great interest in recent years. This are the so-called polarization radiation excited by the Coulomb field of incident particles in periodic structures, parametric X-rays, resonant transition radiation a...

Modulation of DNA methylation levels sensitizes doxorubicin-resistant breast adenocarcinoma cells to radiation-induced apoptosis

Energy Technology Data Exchange (ETDEWEB)

Luzhna, Lidia [Department of Biological Sciences, University of Lethbridge, AB, Canada T1K 3M4 (Canada); Kovalchuk, Olga, E-mail: olga.kovalchuk@uleth.ca [Department of Biological Sciences, University of Lethbridge, AB, Canada T1K 3M4 (Canada)

2010-02-05

Chemoresistant tumors often fail to respond to other cytotoxic treatments such as radiation therapy. The mechanisms of chemo- and radiotherapy cross resistance are not fully understood and are believed to be epigenetic in nature. We hypothesize that MCF-7 cells and their doxorubicin-resistant variant MCF-7/DOX cells may exhibit different responses to ionizing radiation due to their dissimilar epigenetic status. Similar to previous studies, we found that MCF-7/DOX cells harbor much lower levels of global DNA methylation than MCF-7 cells. Furthermore, we found that MCF-7/DOX cells had lower background apoptosis levels and were less responsive to radiation than MCF-7 cells. Decreased radiation responsiveness correlated to significant global DNA hypomethylation in MCF-7/DOX cells. Here, for the first time, we show that the radiation resistance of MCF-7/DOX cells can be reversed by an epigenetic treatment - the application of methyl-donor SAM. SAM-mediated reversal of DNA methylation led to elevated radiation sensitivity in MCF-7/DOX cells. Contrarily, application of SAM on the radiation sensitive and higher methylated MCF-7 cells resulted in a decrease in their radiation responsiveness. This data suggests that a fine balance of DNA methylation is needed to insure proper radiation and drug responsiveness.

Radiation resistance of concrete of nuclear reactor vessel

International Nuclear Information System (INIS)

Belyakov, V.V.; Denisov, A.V.; Korenevskij, V.V.; Muzalevskij, L.P.; Dubrovskij, V.B.; Ivanov, D.A.; Nazarov, I.L.; Sashin, N.L.

1992-01-01

Results of calculational-experimental determination of radiation resistance for concrete bases on limestone gravel and quartz sand, which are the most perspective materials for manufacturing prestressed concrete of the VG-400 reactor vessel are considered. Material samples under investigation were irradiated in the channels of the IBR-2 research reactor for the purpose of the calcultional result verification

Radiation-induced structural transitions in composite materials with strong interaction of polymer components

International Nuclear Information System (INIS)

Zaikin, Yu.A.; Koztaeva, U.P.

2002-01-01

characteristic feature of the measured IF spectra is a point in the temperature scale (about 150-170 deg. C) where all the curves of IF temperature dependencies for different irradiation doses intersect. IF dose dependence at the temperature lower than the intersection point can be related to radiation-induced structural alterations in the less radiation-resistant structural component and that at the higher temperature characterizes structural state of the high-resistant part of the composite. A special procedure is developed in this paper to separate the 'filler-based' and the 'binder-based' relaxation maximums. Determination of the dose dependence of temperature positions, widths and heights of the two IF peaks, allows to control changes in characteristics of thermally activated glassy transition, mass redistribution and radiation-induced structural alterations in a composite

Development of radiation resistant magnets for JHF/J-PARC project

CERN Document Server

Tanaka, K H; Takahashi, H; Agari, K; Toyoda, A; Sato, Y; Minakawa, M; Noumi, H; Yamanoi, Y; Ieiri, M; Katoh, Y; Yamada, Y; Suzuki, Y; Takasaki, M; Birumachi, T; Tsukuda, S; Saitoh, Y; Saitô, N; Yahata, K; Kato, K; Tanaka, H; 10.1109/TASC.2004.829681

2004-01-01

A series of the R&D works on the radiation resistant magnets for the Japan Hadron Facility (JHF) project has been continued at the High Energy Accelerator Research Organization (KEK). The JHF is a high- energy part of the Japanese high intensity Particle Accelerator Research Complex (J-PARC), which is Japanese next-generation high- intensity accelerator project. The main JHF accelerator is the 50 GeV proton synchrotron and will provide high intensity 15 mu A proton beam for various nuclear and particle physics experiments. This time, the actual sized completely-inorganic radiation-resistant quadrupole magnet, designed for the 50 GeV proton beam transportation, was manufactured successfully by using mineral insulation magnet cable (MIC). The assembling procedure and the test results are presented in this issue. (8 refs).

Resistive field structures for semiconductor devices and uses therof

Science.gov (United States)

Marinella, Matthew; DasGupta, Sandeepan; Kaplar, Robert; Baca, Albert G.

2017-09-12

The present disclosure relates to resistive field structures that provide improved electric field profiles when used with a semiconductor device. In particular, the resistive field structures provide a uniform electric field profile, thereby enhancing breakdown voltage and improving reliability. In example, the structure is a field cage that is configured to be resistive, in which the potential changes significantly over the distance of the cage. In another example, the structure is a resistive field plate. Using these resistive field structures, the characteristics of the electric field profile can be independently modulated from the physical parameters of the semiconductor device. Additional methods and architectures are described herein.

Radiative heat transfer in honeycomb structures-New simple analytical and numerical approaches

International Nuclear Information System (INIS)

Baillis, D; Coquard, R; Randrianalisoa, J

2012-01-01

Porous Honeycomb Structures present the interest of combining, at the same time, high thermal insulating properties, low density and sufficient mechanical resistance. However, their thermal properties remain relatively unexplored. The aim of this study is the modelling of the combined heat transfer and especially radiative heat transfer through this type of anisotropic porous material. The equivalent radiative properties of the material are determined using ray-tracing procedures inside the honeycomb porous structure. From computational ray-tracing results, simple new analytical relations have been deduced. These useful analytical relations permit to determine radiative properties such as extinction, absorption and scattering coefficients and phase function functions of cell dimensions and optical properties of cell walls. The radiative properties of honeycomb material strongly depend on the direction of propagation. From the radiative properties computed, we have estimated the radiative heat flux passing through slabs of honeycomb core materials submitted to a 1-D temperature difference between a hot and a cold plate. We have compared numerical results obtained from Discrete Ordinate Method with analytical results obtained from Rosseland-Deissler approximation. This approximation is usually used in the case of isotropic materials. We have extended it to anisotropic honeycomb materials. Indeed a mean over incident directions of Rosseland extinction coefficient is proposed. Results tend to show that Rosseland-Deissler extended approximation can be used as a first approximation. Deviation on radiative conductivity obtained from Rosseland-Deissler approximation and from the Discrete Ordinated Method are lower than 6.7% for all the cases studied.

Electromagnetic radiation of electrons in periodic structures

International Nuclear Information System (INIS)

Potylitsyn, Alexander Petrovich

2011-01-01

Periodic magnetic structures (undulators) are widely used in accelerators to generate monochromatic undulator radiation (UR) in the range from far infrared to the hard X-ray region. Another periodic crystalline structure is used to produce quasimonochromatic polarized photon beams via the coherent bremsstrahlung mechanism (CBS). Due to such characteristics as monochromaticity, polarization and adjustability, these types of radiation is of large interest for applied and basic research of accelerator-emitted radiation. The book provides a detailed overview of the fundamental principles behind electromagnetic radiation emitted from accelerated charged particles (e.g. UR, CBS, radiation of fast electrons in Laser flash fields) as well as a unified description of relatively new radiation mechanisms which attracted great interest in recent years. This are the so-called polarization radiation excited by the Coulomb field of incident particles in periodic structures, parametric X-rays, resonant transition radiation and the Smith-Purcell effect. Characteristics of such radiation sources and perspectives of their usage are discussed. The recent experimental results as well as their interpretation are presented. (orig.)

Role of Mn2+ and Compatible Solutes in the Radiation Resistance of Thermophilic Bacteria and Archaea

Directory of Open Access Journals (Sweden)

Kimberly M. Webb

2012-01-01

Full Text Available Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-myo-inositol phosphate in the radiation resistance of aerobic and anaerobic thermophiles. We found that the IR resistance of the thermophilic bacteria Rubrobacter xylanophilus and Rubrobacter radiotolerans was highly correlated to the accumulation of high intracellular concentration of trehalose in association with Mn, supporting the model of Mn2+-dependent ROS scavenging in the aerobes. In contrast, the hyperthermophilic archaea Thermococcus gammatolerans and Pyrococcus furiosus did not contain significant amounts of intracellular Mn, and we found no significant antioxidant activity from mannosylglycerate and di-myo-inositol phosphate in vitro. We therefore propose that the low levels of IR-generated ROS under anaerobic conditions combined with highly constitutively expressed detoxification systems in these anaerobes are key to their radiation resistance and circumvent the need for the accumulation of Mn-antioxidant complexes in the cell.

Role of Mn2+ and compatible solutes in the radiation resistance of thermophilic bacteria and archaea.

Science.gov (United States)

Webb, Kimberly M; DiRuggiero, Jocelyne

2012-01-01

Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR) in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS) generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-myo-inositol phosphate in the radiation resistance of aerobic and anaerobic thermophiles. We found that the IR resistance of the thermophilic bacteria Rubrobacter xylanophilus and Rubrobacter radiotolerans was highly correlated to the accumulation of high intracellular concentration of trehalose in association with Mn, supporting the model of Mn(2+)-dependent ROS scavenging in the aerobes. In contrast, the hyperthermophilic archaea Thermococcus gammatolerans and Pyrococcus furiosus did not contain significant amounts of intracellular Mn, and we found no significant antioxidant activity from mannosylglycerate and di-myo-inositol phosphate in vitro. We therefore propose that the low levels of IR-generated ROS under anaerobic conditions combined with highly constitutively expressed detoxification systems in these anaerobes are key to their radiation resistance and circumvent the need for the accumulation of Mn-antioxidant complexes in the cell.

Characterization of radiation-resistant vegetative bacteria in beef

International Nuclear Information System (INIS)

Welch, A.B.; Maxcy, R.B.

1975-01-01

Ground beef contains numerous microorganisms of various types. The commonly recognized bacteria are associated with current problems of spoilage. Irradiation, however, contributes a new factor through selective destruction of the microflora. The residual microorganisms surviving a nonsterilizing dose are predominantly gram-negative coccobacilli. Various classifications have been given, e.g., Moraxella, Acinetobacter, Achromobacter, etc. For a more detailed study of these radiation-resistant bacteria occurring in ground beef, an enrichment procedure was used for isolation. By means of morphological and biochemical tests, most of the isolates were found to be Moraxella, based on current classifications. The range of growth temperatures was from 2 to 50 C. These bacteria were relatively heat sensitive, e.g., D 10 of 5.4 min at 70 0 C or less. The radiation resistance ranged from D 10 values of 273 to 2,039 krad. Thus, some were more resistant than any presently recognized spores. A reference culture of Moraxella osloensis was irradiated under conditions comparable to the enrichment procedure used with the ground beef. The only apparent changes were in morphology and penicillin sensitivity. However, after a few subcultures these bacteria reverted to the characteristics of the parent strain. Thus, it is apparent that these isolates are a part of the normal flora of ground beef and not aberrant forms arising from the irradiation procedure. The significance, if any, of these bacteria is not presently recognized. (auth)

Endogenous superoxide dismutase and catalase activities and radiation resistance in mouse cell lines

International Nuclear Information System (INIS)

Davy, C.A.; Tesfay, Z.; Jones, J.; Rosenberg, R.C.; McCarthy, C.; Ostrand-Rosenberg, S.

1988-01-01

The relationship between the endogenous cytoplasmic levels of the enzymes superoxide dismutase and catalase and the inhibition of cell proliferation by γ-radiation has been studied in 11 mouse cell lines. The resistance of these mouse cell lines to radiation was found to vary by over 25-fold. No correlation was found between the cytoplasmic level of CuZn-superoxide dismutase or catalase and the resistance to radiation as measured by extrapolation number (EN), quasi-threshold dose (Dsub(q)), or Dsub(o). None of the cell lines had detectable cytoplasmic Mn-superoxide dismutase. The apparent Ksub(i) of potassium cyanide for mouse CuZn-superoxide dismutase was determined (Ksub(i) = 6.5 μmol dm -3 ). (author)

Prediction of Ionizing Radiation Resistance in Bacteria Using a Multiple Instance Learning Model.

Science.gov (United States)

Aridhi, Sabeur; Sghaier, Haïtham; Zoghlami, Manel; Maddouri, Mondher; Nguifo, Engelbert Mephu

2016-01-01

Ionizing-radiation-resistant bacteria (IRRB) are important in biotechnology. In this context, in silico methods of phenotypic prediction and genotype-phenotype relationship discovery are limited. In this work, we analyzed basal DNA repair proteins of most known proteome sequences of IRRB and ionizing-radiation-sensitive bacteria (IRSB) in order to learn a classifier that correctly predicts this bacterial phenotype. We formulated the problem of predicting bacterial ionizing radiation resistance (IRR) as a multiple-instance learning (MIL) problem, and we proposed a novel approach for this purpose. We provide a MIL-based prediction system that classifies a bacterium to either IRRB or IRSB. The experimental results of the proposed system are satisfactory with 91.5% of successful predictions.

Radiation shielding wall structure

International Nuclear Information System (INIS)

Nishimura, Yoshitaka; Oka, Shinji; Kan, Toshihiko; Misato, Takeshi.

1990-01-01

A space between a pair of vertical steel plates laterally disposed in parallel at an optional distance has a structure of a plurality of vertically extending tranks partitioned laterally by vertically placed steel plates. Then, cements are grouted to the tranks. Strip-like steel plates each having a thickness greater than the gap between the each of the vertically placed steel plates and the cement are bonded each at the surface for each of the vertically placed steel plates opposing to the cements. A protrusion of a strip width having radiation shielding performance substantially identical with that by the thickness of the cement is disposed in the strip-like steel plates. With such a constitution, a safety radiation shielding wall structure with no worry of radiation intrusion to gaps, if formed, between the steel plates and the grouted cements due to shrinkage of the cements. (I.N.)

Role of Mn2+ and Compatible Solutes in the Radiation Resistance of Thermophilic Bacteria and Archaea

OpenAIRE

Webb, Kimberly M.; DiRuggiero, Jocelyne

2012-01-01

Radiation-resistant bacteria have garnered a great deal of attention from scientists seeking to expose the mechanisms underlying their incredible survival abilities. Recent analyses showed that the resistance to ionizing radiation (IR) in the archaeon Halobacterium salinarum is dependent upon Mn-antioxidant complexes responsible for the scavenging of reactive oxygen species (ROS) generated by radiation. Here we examined the role of the compatible solutes trehalose, mannosylglycerate, and di-m...

Radiation hardening of InP solar cells for space applications

International Nuclear Information System (INIS)

Vilela, M. F.; Freundlich, A.; Monier, C.; Newman, F.; Aguilar, L.

1998-01-01

The aim of this work is to develop a radiation resistant thin InP-based solar cells for space applications on more mechanically resistant, lighter, and cheaper substrates. In this paper, we present the development of a p + /nn + InP-based solar cell structures with very thin emitter and base layers. A thin emitter helps to increase the collection of carriers generated by high energy incident photons from the solar spectrum. The use of a thin n base structure should improve the radiation resistance of this already radiation resistant technology. A remarkable improvement of high energy photons response is shown for InP solar cells with emitters 400 A thick

Analysis of QTL for resistance to radiation in rice

International Nuclear Information System (INIS)

Zhao Fei; Zhou Yifeng; Ren Sanjuan; Fu Junjie; Zhuang Jieyun; Shen Shengquan

2010-01-01

The recombinant inbred line (RIL) population derived from rice variates Zhenshan 97B/Miyang 46 and their genetic linkage maps were used to map QTLs controlling resistant to radiation. The trait was measured by the relative germination rate (RGR) and the relative surviving plant rate (RSPR) after the seeds of each line treated with γ-rays irradiation at two 350 and 550 Gy. The results indicated that the lines treated with γ-irradiation showed different performance in resistance to radiation. Under the treatment of 350 Gy, two QTLs with additive effects were detected, of which qRR (g) 81 was only significant for relative germination rate, and it had the positive additive effects from the male parent, explaining 6.53% of the total phenotypic variations. The qRR(s)2-2 was another significant one for relative surviving plant rate, whose positive effects came from the female parent,explaining 12.81% of the total phenotypic variations. Similarly, 4 QTLs were detected under irradiation dose of 550 Gy, and qRR(g)1-2 and qRR(g)8-2 were detected for relative germination rate, with positive effects coming from female and male parent,respectively,explaining 14.38% of the total variations. qRR(s)5-2 and qRR(s)10 were detected for relative surviving plant rate, with positive effects coming from the male parent, explaining 19.65% of total variations. Under different irradiation dose, 9 pairs of double QTL epistasis effects could be identified in this population. The results suggested that the expression of QTL with resistance to radiation might have relation with the irradiation dose. (authors)

Radiation resistance of paralytic shellfish poison (PSP) toxins

Energy Technology Data Exchange (ETDEWEB)

San Juan, Edith M

2000-04-01

Radiation resistance of paralytic shellfish poison (PSP) toxins, obtained from Pyrodinium bahamense var. compressum in shellstocks of green mussels, was determined by subjecting the semi-purified toxin extract as well as the shellstocks of green mussels to high doses of ionizing radiation of 5, 10, 15 and 20 kGy. The concentration of the PSP toxins was determined by the Standard Mouse Bioassay (SMB) method. The radiation assistance of the toxins was determined by plotting the PSP toxin concentration versus applied dose in a semilog paper. The D{sub 10} value or decimal reduction dose was obtained from the straight line which is the dose required to reduce the toxicity level by 90%. The effects of irradiation on the quality of green mussels in terms of its physico-chemical, microbiological and sensory attributes were also conducted. The effect of irradiation on the fatty acid components of green mussels was determined by gas chromatography. Radiation resistance of the PSP toxins was determined to be lower in samples with initially high toxicity level as compared with samples with initially low toxicity level. The D{sub 10} values of samples with initially high PSP level were 28.5 kGy in shellstocks of green musssels and 17.5 kGy in the semi-purified toxin extract. When the PSP level was low initially, the D{sub 10} values were as high as 57.5 and 43.5 kGy in shellstocks of green mussels for the two trials, and 43.0 kGy in semi-purified toxin extract. The microbial load of the irradiated mussels was remarkably reduced. No differnce in color and odor characteristics were observed in the mussel samples subjected to varying doses of ionizing radiation. There was darkening in the color of mussel meat and its juice. The concentration of the fatty acid components in the fresh green mussels were considerably higher as compared with those present in the irradiated mussels, though some volatile fatty acids were detected as a result of irradiation. (Author)

Radiation resistance of paralytic shellfish poison (PSP) toxins

International Nuclear Information System (INIS)

San Juan, Edith M.

2000-04-01

Radiation resistance of paralytic shellfish poison (PSP) toxins, obtained from Pyrodinium bahamense var. compressum in shellstocks of green mussels, was determined by subjecting the semi-purified toxin extract as well as the shellstocks of green mussels to high doses of ionizing radiation of 5, 10, 15 and 20 kGy. The concentration of the PSP toxins was determined by the Standard Mouse Bioassay (SMB) method. The radiation assistance of the toxins was determined by plotting the PSP toxin concentration versus applied dose in a semilog paper. The D 10 value or decimal reduction dose was obtained from the straight line which is the dose required to reduce the toxicity level by 90%. The effects of irradiation on the quality of green mussels in terms of its physico-chemical, microbiological and sensory attributes were also conducted. The effect of irradiation on the fatty acid components of green mussels was determined by gas chromatography. Radiation resistance of the PSP toxins was determined to be lower in samples with initially high toxicity level as compared with samples with initially low toxicity level. The D 10 values of samples with initially high PSP level were 28.5 kGy in shellstocks of green musssels and 17.5 kGy in the semi-purified toxin extract. When the PSP level was low initially, the D 10 values were as high as 57.5 and 43.5 kGy in shellstocks of green mussels for the two trials, and 43.0 kGy in semi-purified toxin extract. The microbial load of the irradiated mussels was remarkably reduced. No differnce in color and odor characteristics were observed in the mussel samples subjected to varying doses of ionizing radiation. There was darkening in the color of mussel meat and its juice. The concentration of the fatty acid components in the fresh green mussels were considerably higher as compared with those present in the irradiated mussels, though some volatile fatty acids were detected as a result of irradiation. (Author)

The involvement of topoisomerases and DNA polymerase I in the mechanism of induced thermal and radiation resistance in yeast

International Nuclear Information System (INIS)

Boreham, D.R.; Trivedi, A.; Weinberger, P.; Mitchel, R.E.

1990-01-01

Either an ionizing radiation exposure or a heat shock is capable of inducing both thermal tolerance and radiation resistance in yeast. Yeast mutants, deficient in topoisomerase I, in topoisomerase II, or in DNA polymerase I, were used to investigate the mechanism of these inducible resistances. The absence of either or both topoisomerase activities did not prevent induction of either heat or radiation resistance. However, if both topoisomerase I and II activities were absent, the sensitivity of yeast to become thermally tolerant (in response to a heat stress) was markedly increased. The absence of only topoisomerase I activity (top1) resulted in the constitutive expression of increased radiation resistance equivalent to that induced by a heat shock in wild-type cells, and the topoisomerase I-deficient cells were not further inducible by heat. This heat-inducible component of radiation resistance (or its equivalent constitutive expression in top1 cells) was, in turn, only a portion of the full response inducible by radiation. The absence of polymerase I activity had no detectable effect on either response. Our results indicate that the actual systems that confer resistance to heat or radiation are independent of either topoisomerase activity or DNA polymerase function, but suggest that topoisomerases may have a regulatory role during the signaling of these mechanisms. The results of our experiments imply that maintenance of correct DNA topology prevents induction of the heat-shock response, and that heat-shock induction of a component of the full radiation resistance in yeast may be the consequence of topoisomerase I inactivation

Radiation resistance of elastomers

International Nuclear Information System (INIS)

Hourquebie, P.; Bigarre, J.; Forveille, J.L.; Raby, J.; Lazare, L.

2002-01-01

The COMOR group is a network of laboratories from both the CEA and the CNRS. This network is particularly involved in fundamental and applied studies on the ageing of polymers under irradiation. COMOR has studied the ageing of EPDM (ethylene-propylene-diene-monomer) because this elastomer is often used in nuclear environment (in cable coating for instance). In this study, we have prepared materials with different formulations and we have characterised their use-condition properties (dielectric and mechanical) before and after γ irradiation. The dielectric measurements are well adapted to study the oxidation and the crosslinking phenomena which appear during the irradiation ageing. We have shown that after a short time, the oxidation is limited by the diffusion of oxygen. A phenolic antioxidant is not able to protect the polymer against the oxidation. However, we used a concentration typical of a purely thermal stabilisation case (0,1%). On the other hand, a diamine type additive with a concentration of 1% showed efficient stabilisation. The mechanical properties of the regular EPDM are strongly affected by the irradiation but there is little difference with regard to radiation resistance between both types of raw materials. Nevertheless, the NORDEL IP 3725 stabilised with the amine has better initial mechanical properties whereas the NORDEL 2722 offers higher strength above 300 kGy. Our results emphasize the stake of a proper stabilisation of polymers with respect to ionising radiation. (authors)

Development of the radiation-resistant strain of Moraxella osloensis and effect of penicillin G on its growth

International Nuclear Information System (INIS)

Lim, Sangyong; Yun, Hyejeong; Joe, Minho; Kim, Dongho

2009-01-01

A series of repeated exposures to γ-radiation with intervening outgrowth of survivors was used to develop radioresistant cultures of Moraxella osloensis that have been recognized as potential pathogenic microorganism. The D 10 value of the radiation-resistant strain, 5.903±0.006 kGy, was increased by four-fold compared to the parent wild-type strain, 1.637±0.004 kGy. Since most strains of M. osloensis are sensitive to penicillin, we have surveyed the sensitivity of radiation-resistant strain to this antibiotic. When the optical density was monitored after the addition of penicillin G, the radioresistant strain appeared to be more resistant to only a low concentration of penicillin G (0.5 U/ml) than the parent strain. Interestingly, however, there was no apparent difference in the number of viable cells between both strains. Scanning electron microscope data showed that the resistance cells were generally larger than the parent cells, suggesting that this increase in size may cause a higher optical density of radioresistant cells. In conclusion, radiation mutation does not affect the penicillin resistance of M. osloensis.

Development of the radiation-resistant strain of Moraxella osloensis and effect of penicillin G on its growth

Science.gov (United States)

Lim, Sangyong; Yun, Hyejeong; Joe, Minho; Kim, Dongho

2009-07-01

A series of repeated exposures to γ-radiation with intervening outgrowth of survivors was used to develop radioresistant cultures of Moraxella osloensis that have been recognized as potential pathogenic microorganism. The D10 value of the radiation-resistant strain, 5.903±0.006 kGy, was increased by four-fold compared to the parent wild-type strain, 1.637±0.004 kGy. Since most strains of M. osloensis are sensitive to penicillin, we have surveyed the sensitivity of radiation-resistant strain to this antibiotic. When the optical density was monitored after the addition of penicillin G, the radioresistant strain appeared to be more resistant to only a low concentration of penicillin G (0.5 U/ml) than the parent strain. Interestingly, however, there was no apparent difference in the number of viable cells between both strains. Scanning electron microscope data showed that the resistance cells were generally larger than the parent cells, suggesting that this increase in size may cause a higher optical density of radioresistant cells. In conclusion, radiation mutation does not affect the penicillin resistance of M. osloensis.

Development of the radiation-resistant strain of Moraxella osloensis and effect of penicillin G on its growth

Energy Technology Data Exchange (ETDEWEB)

Lim, Sangyong; Yun, Hyejeong; Joe, Minho [Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of); Kim, Dongho [Radiation Research Division for Biotechnology, Korea Atomic Energy Research Institute, Jeongeup 580-185 (Korea, Republic of)], E-mail: fungikim@kaeri.re.kr

2009-07-15

A series of repeated exposures to {gamma}-radiation with intervening outgrowth of survivors was used to develop radioresistant cultures of Moraxella osloensis that have been recognized as potential pathogenic microorganism. The D{sub 10} value of the radiation-resistant strain, 5.903{+-}0.006 kGy, was increased by four-fold compared to the parent wild-type strain, 1.637{+-}0.004 kGy. Since most strains of M. osloensis are sensitive to penicillin, we have surveyed the sensitivity of radiation-resistant strain to this antibiotic. When the optical density was monitored after the addition of penicillin G, the radioresistant strain appeared to be more resistant to only a low concentration of penicillin G (0.5 U/ml) than the parent strain. Interestingly, however, there was no apparent difference in the number of viable cells between both strains. Scanning electron microscope data showed that the resistance cells were generally larger than the parent cells, suggesting that this increase in size may cause a higher optical density of radioresistant cells. In conclusion, radiation mutation does not affect the penicillin resistance of M. osloensis.

Optimum structures for gamma-ray radiation resistant SiC-MOSFETs

Energy Technology Data Exchange (ETDEWEB)

Mitomo, Satoshi; Matsuda, Takuma; Murata, Koichi; Yokoseki, Takashi [Saitama University, Sakuraku (Japan); National Institutes for Quantum and Radiological Science and Technology (QST), Takasaki (Japan); Makino, Takahiro; Takeyama, Akinori; Onoda, Shinobu; Ohshima, Takeshi [National Institutes for Quantum and Radiological Science and Technology (QST), Takasaki (Japan); Okubo, Shuichi; Tanaka, Yuki; Kandori, Mikio; Yoshie, Toru [Sanken Electric Co., Ltd., Niiza, Saitama (Japan); Hijikata, Yasuto [Saitama University, Sakuraku (Japan)

2017-04-15

In order to develop highly radiation-tolerant SiC MOSFETs, we investigated the dependence of the gamma-ray radiation response on the gate oxide thickness and nitridation processes, used for oxide growth and p-well implantation. SiC MOSFETs with a thick gate oxide (60 nm) showed a rapid decrease in the threshold voltage shift ΔV{sub th} of more than 400 kGy, and transitioned to the normally-on state at lower doses than those with a thin gate oxide (35 nm). The MOSFETs with gate oxides treated with lower concentrations of N{sub 2}O (10%) demonstrated a higher radiation tolerance (ΔV{sub th}, channel mobility, and subthreshold swing) than with a 100% N{sub 2}O treatment. The MOSFETs with more p-well implantation steps (three steps) showed a smaller negative shift of the threshold voltage relative to those implanted with two steps. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Human genetic marker for resistance to radiations and chemicals. 1998 annual progress report

International Nuclear Information System (INIS)

Lieberman, H.B.

1998-01-01

'The broad objective of the project is to understand the molecular basis for the response of cells to radiations and chemicals, with the pragmatic goal of being able to identify human subpopulations that are exceptionally sensitive to DNA damaging agents. The project focuses on HRAD9, a human orthologue of the fission yeast Schizosaccharomyces pombe gene rad9. S. pombe rad9::ura4+ mutant cells are highly sensitive to ionizing radiation, UV and many chemicals, such as the DNA synthesis inhibitor hydroxyurea. They also lack the ability to delay cycling transiently in S phase or in G2 following a block in DNA replication or after incurring DNA damage, respectively -i.e., they lack checkpoint controls. The attempt by mutant cells to progress through mitosis in the absence of fully intact DNA accounts at least in part for their sensitivity to DNA damaging agents. Cells bearing rad9::ura4+ also aberrantly regulate UVDE, an enzyme that participates in a secondary DNA excision repair pathway. The key role played by S. pombe rad9 in promoting resistance to chemicals and radiations suggests that the evolutionarily conserved human cognate also has important functions in mammals. The first set of aims in this proposal centers on characterizing the structure and expression of HRAD9, to assess structure/function relationships and potentially link protein activity to a specific tissue. The next set of aims focuses on determining the role of HRAD9 in radio/chemoresponsiveness and cancer.'

Investigating mechanical behavior and radiation resistant of fuel rods clad in nuclear power plant

International Nuclear Information System (INIS)

Sedgh Kerdar, A.

1999-01-01

The important factors for selection of material for use in nuclear reactors is similar to those for other engineering applications. There are however other parameters which are of importance when materials are going to be used in high radiation environments. These parameters are compatibility in intense nuclear radiation field, high resistance against corrosion and other characteristics such as thermal conductivity, machinability and suitable welding properties. This factors discussed in chapter one. In additions to the materials used as fuel, moderator, controls, etc., which have clear and stringent nuclear requirements, other materials may be necessary in a reactor to provide structural strength and other desired properties. For a materials used in a reactor core, the single most important property is its capacity for neutron absorption. Other properties, such as temperature and radiation stability, mechanical strength, corrosion resistance, etc., also receive much attention in selecting material for a specific application. Obviously, far more can be said about each of the potential metals than is possible in chapter two. We shall limit our attention to those metals of current nuclear interest, i.e., aluminium, beryllium magnesium, zirconium, austenitic stainless steels, nickel base alloys, and in factory metals (Nb and Mo). Interactions between matter and different radiations like Neutrons, protons, Gamma , Beta and Alpha rays in nuclear reactors induced important changes in properties of materials.There are five mechanism responsible for radiation induced changes in solids: ionization, vacancy formation, interstitial formation, creation of impurities caused by nuclear reactions and displacements spikes under the local thermal environment. Due to presence of many electrons in metals ionization does not play a major role in metals only the other four mechanisms are relevant to metals and their alloys. Generally speaking formation of many vacancies and

Optical emission behavior and radiation resistance of epoxy resins

International Nuclear Information System (INIS)

Kawanishi, Shunichi; Udagawa, Akira; Hagiwara, Miyuki

1987-11-01

To make clear a mechanism of radiation resistance of epoxy resin systems, a role of energy trapping site induced in bisphenol A type epoxy resins cured with 4 kinds of aromatic amines (Φ N ) was studied in comparison with the case of aliphatic amine curing system through a measurement of optical emission. In the system of the epoxy resin cured with DETA, the optical emission from an excited state of bisphenol A unit of epoxy resin and a charge transfer complex was observed. On the other hand, the optical emission from Φ N was observed in the aromatic amine curing system. Their excitation spectrum consists of peaks of absorption spectrum of BA and those of Φ N , showing that the excited state of Φ N is formed through the excitation of both BA and Φ N . Therefore, the excited energy of BA transfers to the excited state of Φ N . Emission intensity of Φ N band was 20 ∼ 100 times as large as that of BA. These results indicate that the radiation energy is effectively released as an optical emission from excited state of Φ N in the epoxy resin when cured with aromatic amine. It can be concluded from the above results that aromatic amine hardeners contribute to enhancement of the radiation resistance of epoxy resin by acting as an energy transfer agent. (author)

Structure of single-chain single crystals of isotactic polystyrene and their radiation resistance

International Nuclear Information System (INIS)

Bu Haishan; Cao Jie; Xu Shengyong; Zhang Ze

1997-01-01

The structure of the single-chain single crystals of isotactic polystyrene (i-PS) was investigated by electron diffraction (ED) and high resolution electron microscopy (HREM). The nano-scale single-chain single crystals were found to be very stable to electron irradiation. According to the unit cell of i-PS crystals, the reflection rings in ED pattern and the lattice fringes in HREM images could be indexed, but the lower-index diffractions were not found. It is proposed that the single-chain single crystals are very small, thus secondary electrons may be allowed to escape and radiation damage is highly reduced, and that there are less lower-index lattice planes in the single-chain single crystals to provide sufficient diffraction intensity for recording. HREM images can be achieved at room temperature in the case of single-chain single crystals because of its stability to electron irradiation, therefore, this might be a novel experimental approach to the study of crystal structure of macromolecules

Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream

International Nuclear Information System (INIS)

Rizzo, L.; Fiorentino, A.; Anselmo, A.

2012-01-01

The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC > 256 μg/mL) and SMZ (MIC > 1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1 mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t 1/2 = 24 min) 1/2 = 99 min) 1/2 = 577 min). Accordingly, the risk of the development of resistance to SMZ in surface water is significantly higher compared to CPX and AMX. - Highlights: ► Solar radiation did not affect E. coli strain resistance to AMX and SMZ. ► Solar radiation affected the resistance of one E. coli strain to CPX. ► MIC for CPX decreased by 33% after 180 min of solar irradiation. �

Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream

Energy Technology Data Exchange (ETDEWEB)

Rizzo, L., E-mail: l.rizzo@unisa.it [Department of Civil Engineering, University of Salerno, via Ponte don Melillo, 1-84084 Fisciano (Italy); Fiorentino, A. [Department of Civil Engineering, University of Salerno, via Ponte don Melillo, 1-84084 Fisciano (Italy); Anselmo, A. [Pluriacque, via Alento, 84060 Prignano Cilento (Italy)

2012-06-15

The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC > 256 {mu}g/mL) and SMZ (MIC > 1024 {mu}g/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1 mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t{sub 1/2} = 24 min) < AMX (t{sub 1/2} = 99 min) < SMZ (t{sub 1/2} = 577 min). Accordingly, the risk of the development of resistance to SMZ in surface water is significantly higher compared to CPX and AMX. - Highlights: Black-Right-Pointing-Pointer Solar radiation did not affect E. coli strain resistance to AMX and SMZ. Black-Right-Pointing-Pointer Solar radiation affected the resistance of one E. coli strain

Radiation resistance and comparative performance of ITO/InP and n/p InP homojunction solar cells

International Nuclear Information System (INIS)

Weinberg, I.; Swartz, C.K.; Hart, R.E. Jr.; Coutts, T.J.

1988-09-01

The radiation resistance of ITO/InP cells processed by DC magnetron sputtering is compared to that of standard n/p InP and GaAs homojunction cells. After 20 MeV proton irradiations, it is found that the radiation resistance of the present ITO/InP cell is comparable to that of the n/p homojunction InP cell and that both InP cell types have radiation resistance significantly greater than GaAs. The relatively lower radiation resistance, observed at higher fluence, for the InP cell with the deepest junction depth, is attributed to losses in the cells emitter region. Diode parameters obtained from I sub sc - V sub oc plots, data from surface Raman spectroscopy, and determinations of surface conductivity types are used to investigate the configuration of the ITO/InP cells. It is concluded that thesee latter cells are n/p homojunctions, the n-region consisting of a disordered layer at the oxide semiconductor

Influence of preliminary radiation-oxidizing treatment on the corrosion resistance of zirconium in conditions of action of ionizing radiation

International Nuclear Information System (INIS)

Garibov, A. A.; Aliyev, A. G.; Agayev, T. N.; Velibekova, G. Z.

2004-01-01

Today mainly water-cooled nuclear reactors predominate in atomic energetics. For safe work of nuclear reactors detection of accumulation process of explosives, formed during radiation and temperature influence on heat-carriers in contact with materials of nuclear reactors in normal and emergency regimes of work is of great importance. The main sources of molecular hydrogen formation in normal and emergency regimes are the processes of liquid and vaporous water in vapo metallic reaction [1-5]. At the result of these processes molecular hydrogen concentration in heat-carrier composition always exceeds theoretically expected concentration. One of the main ways to solve the problem of water-cooled reactors safety is detection of possibilities to raise material resistance of fuel elements and heat carrier to joint action of ionizing radiation and temperature. The second way is inhibition of radiation-catalytic activity of construction materials' surface during the process of water decomposition. It's been established, that one of the ways to raise resistance of zirconium materials to the influence of ionizing radiation is formation of thin oxide film on the surface of metals. In the given work the influence of preliminary oxidizing treatment of zirconium surface on its radiation-catalytic activity during the process of water decomposition. With this aim zirconium is exposed to preliminary influence of gamma-quantum in contact with hydrogen peroxide at different meanings of absorbed radiation dose

Improved ozone resistance of styrene-butadiene rubber cured by a combination of sulfur and ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Silverman, J.

1995-01-01

Fourier Transform (FTIR) studies performed in this work indicate that high ozone resistance of Styrene-Butadiene Rubber (SBR) formulations cured by a combination of sulfur and ionizing radiation is associated with unusually high vinyl concentration. On the other hand, sulfur cured SBR formulations with low vinyl concentration have poor ozone resistance. Curing with peroxides which involves chemistry similar to that of radiation curing, also leads to high vinyl concentration (relative to sulfur curing) and high ozone resistance. Increasing the absorbed dose in sulfur-radiation cured samples decreased the high vinyl content to a point where the ozone resistance declined greatly. Carbon black was shown to reduce the absorption of both the transvinylene and the vinyl unsaturation groups, but not to the same extent in all formulations. Also, the carbon black seems to play a greater role in the absorption of the unsaturation as sulfur increases. (Author)

Improved ozone resistance of styrene-butadiene rubber cured by a combination of sulfur and ionizing radiation

International Nuclear Information System (INIS)

Basfar, A.A.; Silverman, Joseph

1995-01-01

Fourier Transform Infrared (FTIR) studies performed in this work indicate that high ozone resistance of Styrene-Butadiene Rubber (SBR) formulations cured by a combination of sulfur and ionizing radiation is associated with unusually high vinyl concentration. On the other hand, sulfur cured SBR formulations with low vinyl concentration have poor ozone resistance. Curing with peroxides which involves chemistry similar to that of radiation curing, also leads to high vinyl concentration (relative to sulfur curing) and high ozone resistance. Increasing the absorbed dose in sulfur-radiation cured samples decreased the high vinyl content to a point where the ozone resistance declined greatly. Carbon black was shown to reduce the absorption of both the transvinylene and the vinyl unsaturation groups, but not to the same extent in all formulations. Also, the carbon black seems to play a greater role in the absorption of the unsaturation as sulfur increases. (Author)

Problems of photo-radiative action

International Nuclear Information System (INIS)

Milinchuk, V.K.

1985-01-01

The most interesting photo-radiation effects observed in the last few years are discussed, in particular, considerable reduction ip material radiation resistance under the combined effect of ionizing and visible radiation. Intermediate active particles are shown to absorb the light according to the mechanism of ''direct'' absorption and as a result of photo-sensibilization reactions as well. Channels of absorbed light energy dissipation depend on the nature and structure of the intermediate active particles, temperature, light radiation frequency and other parameters. Problems are considered which solution promotes further development of photo-radiation chemistry and that are important for such branches of modern physical chemistry as kinetics and mechanism of elementary processes in organic solids, radiation resistance and ageing of organic polymers

Cross-resistance to radiation in human squamous cell carcinoma cells with induced cisplatin resistance

International Nuclear Information System (INIS)

Komori, Keiichi

1998-01-01

Accumulated evidence indicates that drug resistance is induced in tumor cells treated with a variety of anti-cancer drugs and that there is a possibility of cross-resistance to ionizing radiation associated with induced drug resistance. Most in vitro studies have shown inconsistent results on cross-resistance probably because of different cell lines used and protocols for drug induction. In this study, TE3 human squamous cell carcinoma cell line was treated with a 4-day cycle of cisplatin (cis-diamminedichloroplatinum (II); CDDP) at a concentration yielding 10% cell survival. The treatment was repeated up to 3 cycles. After treatment, cells were tested for CDDP and X-ray sensitivity. One cycle of CDDP treatment induced CDDP resistance with a factor of 1.41 and 2 cycles of the treatment with a factor of 1.86. The resistance factor reached a plateau at 3 cycles of treatment. For analyzing the correlation of CDDP and X-ray resistance, 30 clones from both untreated and 3-cycle treated cells were isolated and analyzed for CDDP and X-ray sensitivity. The sensitivity was expressed as the concentration of drug or dose of X-ray required to reduce the cell survival to x% (Dx). The correlation coefficient of clones with 3-cycle treatment between CDDP and X-ray sensitivity increased gradually by increasing the end point of Dx from D 10 to D 90 , resulting in significant correlation at D 90 . The result suggested that there is a certain common repair-related mechanism affecting both CDDP and X-ray resistance in CDDP-treated cells. (author)

Human Genetic Marker for Resistance to Radiation and Chemicals

International Nuclear Information System (INIS)

Lieberman, Howard B.

2001-01-01

TO characterize the human HRDAD9 gene and evaluate its potential as a biomarker to predict susceptibility to the deleterious health effects potentially caused by exposure to radiations or chemicals present at DOE hazardous waste cleanup sites. HRAD9 is a human gene that is highly conserved throughout evolution. Related genes have been isolated from yeasts and mice, underscoring its biological significance. Most of our previous work involved characterization of the yeast gene cognate, wherein it was determined that the corresponding protein plays a significant role in promoting resistance of cells to radiations and chemicals, and in particular, controlling cell growth in response to DNA damage

Radiation sensitivity of Salmonella isolates relative to resistance to ampicillin, chloramphenicol or gentamicin

Science.gov (United States)

Niemira, Brendan A.; Lonczynski, Kelly A.; Sommers, Christopher H.

2006-09-01

Antibiotic resistance of inoculated bacteria is a commonly used selective marker. Bacteria resistant to the antibiotic nalidixic acid have been shown to have an increased sensitivity to irradiation. The purpose of this research was to screen a collection of Salmonella isolates for antibiotic resistance and determine the association, if any, of antibiotic resistance with radiation sensitivity. Twenty-four clinical isolates of Salmonella were screened for native resistance to multiple concentrations of ampicillin (Amp), chloramphenicol (Chl), or gentamicin (Gm). Test concentrations were chosen based on established clinical minimum inhibitory concentration (MIC) levels, and isolates were classified as either sensitive or resistant based on their ability to grow at or above the MIC. Salmonella cultures were grown overnight at (37 °C) in antibiotic-amended tryptic soy broth (TSB). Native resistance to Gm was observed with each of the 24 isolates (100%). Eight isolates (33%) were shown to be resistant to Amp, while seven isolates (29%) were shown to be resistant to Chl. In separate experiments, Salmonella cultures were grown overnight (37 °C) in TSB, centrifuged, and the cell pellets were re-suspended in phosphate buffer. The samples were then gamma irradiated at doses up to 1.0 kGy. The D10 values (the ionizing radiation dose required to reduce the viable number of microorganisms by 90%) were determined for the 24 isolates and they ranged from 0.181 to 0.359 kGy. No correlation was found between the D10 value of the isolate and its sensitivity or resistance to each of the three antibiotics. Resistance to Amp or Chl is suggested as appropriate resistance marker for Salmonella test strains to be used in studies of irradiation.

Radiation sensitivity of Salmonella isolates relative to resistance to ampicillin, chloramphenicol or gentamicin

International Nuclear Information System (INIS)

Niemira, Brendan A.; Lonczynski, Kelly A.; Sommers, Christopher H.

2006-01-01

Antibiotic resistance of inoculated bacteria is a commonly used selective marker. Bacteria resistant to the antibiotic nalidixic acid have been shown to have an increased sensitivity to irradiation. The purpose of this research was to screen a collection of Salmonella isolates for antibiotic resistance and determine the association, if any, of antibiotic resistance with radiation sensitivity. Twenty-four clinical isolates of Salmonella were screened for native resistance to multiple concentrations of ampicillin (Amp), chloramphenicol (Chl), or gentamicin (Gm). Test concentrations were chosen based on established clinical minimum inhibitory concentration (MIC) levels, and isolates were classified as either sensitive or resistant based on their ability to grow at or above the MIC. Salmonella cultures were grown overnight at (37 o C) in antibiotic-amended tryptic soy broth (TSB). Native resistance to Gm was observed with each of the 24 isolates (100%). Eight isolates (33%) were shown to be resistant to Amp, while seven isolates (29%) were shown to be resistant to Chl. In separate experiments, Salmonella cultures were grown overnight (37 o C) in TSB, centrifuged, and the cell pellets were re-suspended in phosphate buffer. The samples were then gamma irradiated at doses up to 1.0 kGy. The D 10 values (the ionizing radiation dose required to reduce the viable number of microorganisms by 90%) were determined for the 24 isolates and they ranged from 0.181 to 0.359 kGy. No correlation was found between the D 10 value of the isolate and its sensitivity or resistance to each of the three antibiotics. Resistance to Amp or Chl is suggested as appropriate resistance marker for Salmonella test strains to be used in studies of irradiation

Scintillation detectors based on poly-2,4-dimethylstyrene: Structure peculiarities and radiation damage

International Nuclear Information System (INIS)

Gunder, O.A.; Voronkina, N.I.; Kopina, I.V.

1995-01-01

Scintillation detectors based on poly-2,4-dimethyl styrene (P-2,4-DMS) are studied. Investigated is the influence of two methyl groups present in the benzene ring on the energy, spectral and structural characteristics of the polymer. The said factors are assumed to result in the detectors high light output and radiation resistance. It is shown that under radiolysis (77 K) the radiation yield of the paramagnetic centers of P-2,4-DMS exceeds that of polystyrene (PST) by ∼ 1.5. Unlike PST film, the luminescence spectra of P-2,4-DMS are characterized by the presence of both excimer (320-340 nm) and monomer (292 nm) bands. Revealed are the distinction in the nature of the optical characteristics of macroradicals and the efficiency of energy transfer in gamma-irradiated PST and P-2,4-DMS scintillators. The relation between the super-molecular structure of the polymers and the interaction of their macroradicals with molecular O 2 is stated

Structural Biology Meets Drug Resistance: An Overview on Multidrug Resistance Transporters

DEFF Research Database (Denmark)

Shaheen, Aqsa; Iqbal, Mazhar; Mirza, Osman

2017-01-01

. Research on the underlying causes of multidrug resistance in cancerous cells and later on in infectious bacteria revealed the involvement of integral membrane transporters, capable of recognizing a broad range of structurally different molecules as substrates and exporting them from the cell using cellular...... superfamilies, viz., ATP-binding cassette superfamily, major facilitator superfamily and resistance nodulation division superfamily are presented. Further, the future role of structural biology in improving our understanding of drug-transporter interactions and in designing novel inhibitors against MDR pump...... century, mankind has become aware and confronted with the emergence of antibiotic-resistant pathogens. In parallel to the failure of antibiotic therapy against infectious pathogens, there had been continuous reports of cancerous cells not responding to chemotherapy with increase in the duration of therapy...

Isolation of radiation resistant fungal strains from highly radioactive field

International Nuclear Information System (INIS)

Adam, Y.M.; Aziz, N.H.; Attaby, H.S.H.

1995-01-01

This study examined the radiation resistance of fungal flora isolated from the hot-lab around the radiation sources, cobalt 137 and radium 226 . The predominant mould species were: Aspergillus flavus, A. Niger, penicillium chrysogenum, cladosporium herbarum, fusarium oxysporum and alternaria citri. The D 10 values of F. Oxysporum; 2.00 KGy, A. Flavus; 1.40 KGy, P. chrysogenum; 1.15 KGy, and A. citri; 0.95 KGy, are about 1.67, 3.10, 1.92 and 1.36 folds as the D 1 0 values of the same isolates recovered from soil

Synchrotron radiation and structural proteomics

CERN Document Server

Pechkova, Eugenia

2011-01-01

This book presents an overview of the current state of research in both synchrotron radiation and structural proteomics from different laboratories worldwide. The book presents recent research results in the most advanced methods of synchrotron radiation analysis, protein micro- and nano crystallography, X-ray scattering and X-ray optics, coherent X-Ray diffraction, and laser cutting and contactless sample manipulation are described in details. The book focuses on biological applications and highlights important aspects such as radiation damage and molecular modeling.

Development of new materials by utilizing radiation crosslinking

International Nuclear Information System (INIS)

Ueno, Keiji; Uda, Yujiro; Suzuki, Shizuo

1989-01-01

About 30 years have elapsed since the cables by electron beam crosslinking were developed as the first industrial utilization of radiation in Japan. At present about 200 electron beam accelerators are used industrially in Japan, and cable industry ranks at the top, followed by foaming polyethylene and curing, and the preliminary vulcanization of tires. The effect of these irradiations is the reforming of polymers by radiation crosslinking. In cables, the heat resistance and chemical resistance of insulators are improved by radiation crosslinking. By applying radiation crosslinking to polyurethane elastomer, its weakest point, waterproof property, was improved. Moreover, by using this crosslinked polyurethane elastomer for cable coating, the reliability of the sensor cables for brake system was able to be remarkably improved. As another new application of radiation crosslinking process, the improvement of the heat resistance of engineering plasties was examined. The structure of radiation crosslinked urethane elastomer cables, their endurance in hot water and oil, and the life, and the characteristics of sensor cables are reported. Multi-functional monomers, the molecular structure, and the various characteristics of engineering plastics are described. (K.I.)

Evaluation of Radiation Response and Gold Nanoparticle Enhancement in Drug-Resistant Pancreatic Cancer Cells

Science.gov (United States)

Abourabia, Assya

Pancreatic cancer is a major cause of cancer-related death worldwide after lung cancer and colorectal cancer Pancreatic treatment modalities consist of surgery, chemotherapy, and radiation therapy or combination of these therapies. These modalities are good to some extents but they do have some limitations. For example, during the chemotherapy, tumor cells can develop some escape mechanisms and become chemoresistant to protect themselves against the chemo drugs and pass on theses escape mechanisms to their offspring, despite the treatment given. Cancer Cells can become chemoresistant by many mechanisms, for example, decreased drug influx mechanisms, decreased of drug transport molecules, decreased drug activation, altered drug metabolism that diminishes the capacity of cytotoxic drugs, and enhanced repair of DNA damage. Given that some of these chemoresistance mechanisms may impact sensitivity to radiation. Therefore, there is a strong need for a new alternative treatment option to amplify the therapeutic efficacy of radiotherapy and eventually increase the overall efficacy of cancer treatment. Nano-radiation therapy is an emerging and promising modality aims to enhance the therapeutic efficacy of radiotherapy through the use of radiosensitizing nanoparticles. The primary goal of using GNP-enhanced radiation is that GNPs are potent radiosensitizer agents that sensitize the tumor cells to radiation, and these agents promote generation of the free radicals produced by Photo- and Auger- electrons emission at the molecular level which can enhance the effectiveness of radiation-induced cancer cell death. The main aim of this research is to analyze and compare the response to radiation of pancreatic cancer cells, PANC-1, and PANC-1 cells that are resistant to oxaliplatin, PANC-1/OR, and investigate the radiation dose enhancement effect attributable to GNP when irradiating the cells with low-energy (220 kVp) beam at various doses. Based on evidence from the existing

Radiation resistance of lactobacilli isolated from radurized meat relative to growth and environment

International Nuclear Information System (INIS)

Hastings, J.W.; Holzapfel, W.H.; Niemand, J.G.

1986-01-01

Of 113 lactobacilli isolated from radurized (5 kGy) minced meat, 7 Lactobacillus sake strains, 1 L. curvatus strain, and 1 L. farciminis strain were used for radiation resistance studies in a semisynthetic substrate (i.e., modified MRS broth). Five reference Lactobacillus spp. one Staphylococcus aureus strain, and one Salmonella typhimurium strain were used for comparative purposes. All L. sake isolates exhibited the phenomenon of being more resistant to gamma-irradiation in the exponential (log) phase than in the stationary phase of their growth cycles by a factor of 28%. Four reference strains also exhibited this phenomenon, with L. sake (DSM 20017) showing a 68% increase in resistance in the log phase over the stationary phase. This phenomenon was not common to all bacteria tested and is not common to all strains with high radiation resistance. Four L. sake isolates and three reference strains were used in radiation sensitivity testing in a natural food system (i.e., meat). The bacteria were irradiated in minced meat and packaged under four different conditions (air, vacuum, CO 2 , and N 2 ). Organisms exhibited the highest death rate (lowest D 10 values [doses required to reduce the logarithm of the bacterial population by 1] under CO 2 packaging conditions, but resistance to irradiation was increased under N 2 . The D 10 values of the isolates were generally greater than those of the reference strains. The D 10 values were also higher (approximately two times) in meat than in a semisynthetic growth medium

Theory of the high base resistivity n(+)pp(+) silicon solar cell and its application to radiation damage effects

Science.gov (United States)

Goradia, C.; Weinberg, I.

1985-01-01

Particulate radiation in space is a principal source of silicon solar cell degradation, and an investigation of cell radiation damage at higher base resistivities appears to have implication toward increasing solar cell and, therefore, useful satellite lifetimes in the space environment. However, contrary to expectations, it has been found that for cells with resistivities of 84 and 1250 ohm cm, the radiation resistance decreases as cell base resistivity increases. An analytical solar-cell computer model was developed with the objective to determine the reasons for this unexpected behavior. The present paper has the aim to describe the analytical model and its use in interpreting the behavior, under irradiation, of high-resistivity solar cells. Attention is given to boundary conditions at the space-charge region edges, cell currents, cell voltages, the generation of the theoretical I-V characteristic, experimental results, and computer calculations.

Phenotypical and biochemical characterisation of resistance for parasitic weed (Orobanche foetida Poir.) in radiation-mutagenised mutants of chickpea.

Science.gov (United States)

Brahmi, Ines; Mabrouk, Yassine; Brun, Guillaume; Delavault, Philippe; Belhadj, Omrane; Simier, Philippe

2016-12-01

Some radiation-mutagenised chickpea mutants potentially resistant to the broomrape, Orobanche foetida Poir., were selected through field trials. The objectives of this work were to confirm resistance under artificial infestation, in pots and mini-rhizotron systems, and to determine the developmental stages of broomrape affected by resistance and the relevant resistance mechanisms induced by radiation mutagenesis. Among 30 mutants tested for resistance to O. foetida, five shared strong resistance in both pot experiments and mini-rhizotron systems. Resistance was not complete, but the few individuals that escaped resistance displayed high disorders of shoot development. Results demonstrated a 2-3-fold decrease in stimulatory activity of root exudates towards broomrape seed germination in resistant mutants in comparison with non-irradiated control plants and susceptible mutants. Resistance was associated with an induction of broomrape necrosis early during infection. When infested, most of the resistant mutants shared enhanced levels of soluble phenolic contents, phenylalanine ammonia lyase activity, guaiacol peroxidase activity and polyphenol oxidase activity, in addition to glutathione and notably ascorbate peroxidase gene expression in roots. Results confirmed enhanced resistance in chickpea radiation-mutagenised mutants, and demonstrated that resistance is based on alteration of root exudation, presumed cell-wall reinforcement and change in root oxidative status in response to infection. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Radiation Effects of n-type, Low Resistivity, Spiral Silicon Drift Detector Hybrid Systems

International Nuclear Information System (INIS)

Chen, W.; De Geronimo, G.; Carini, G.A.; Gaskin, J.A.; Keister, J.W.; Li, S.; Li, Z.; Ramsey, B.D.; Siddons, D.P.; Smith, G.C.; Verbitskaya, E.

2011-01-01

We have developed a new thin-window, n-type, low-resistivity, spiral silicon drift detector (SDD) array - to be used as an extraterrestrial X-ray spectrometer (in varying environments) for NASA. To achieve low-energy response, a thin SDD entrance window was produced using a previously developed method. These thin-window devices were also produced on lower resistivity, thinner, n-type, silicon material, effectively ensuring their radiation hardness in anticipation of operation in potentially harsh radiation environments (such as found around the Jupiter system). Using the Indiana University Cyclotron Facility beam line RERS1, we irradiated a set of suitable diodes up to 5 Mrad and the latest iteration of our ASICs up to 12 Mrad. Then we irradiated two hybrid detectors consisting of newly, such-produced in-house (BNL) SDD chips bonded with ASICs with doses of 0.25 Mrad and 1 Mrad. Also we irradiated another hybrid detector consisting of previously produced (by KETEK) on n-type, high-resistivity SDD chip bonded with BNL's ASICs with a dose of 1 Mrad. The measurement results of radiated diodes (up to 5 Mrad), ASICs (up to 12 Mrad) and hybrid detectors (up to 1 Mrad) are presented here.

Susceptibility to radiation-induced mammary carcinoma in genetically resistant Copenhagen rats

International Nuclear Information System (INIS)

Kamiya, Kenji; Nitta, Yumiko; Gould, M.N.

2000-01-01

The objective of this experiment was to compare the cellular basis of mammary cancer induction by a chemical carcinogen with induction by ionizing radiation in three strains of rats (inbred that have different genetic susceptibilities: COP rats, F344 rats, and WF rats). Rats were given a single intraperitoneal injection of 50 mg MNU/kg body weight as a mammary-tumor-inducing chemical carcinogen and were irradiated with a 3.0 Gy dose of 60 Co gamma rays at a dose rate of 26.58±1.19 cGy/min. The rats were inspected weekly, and they were killed and necropsied whenever palpable tumors were detected or they became moribund. The histopathological and immunohistochemical characteristics of the mammary tumors were investigated. A transplantation experiment using selected primary mammary tumors that developed in COP rats exposed to gamma rays was also performed to investigate the transplantability of mammary tumors induced by ionizing radiation. The sensitivity of the WF and F344 rats and the resistance of the COP rats to mammary carcinoma induction by the chemical carcinogen MNU was confirmed. In contrast to the chemical carcinogens, no difference in susceptibility to radiation induction of mammary carcinomas was detected among the three strains of rats, and immunohistochemical examination indicated that the radiation-induced carcinomas consisted of more highly differentiated cells than the MNU-induced cancers. The results of the experiment appear to support the hypothesis that differentiated mammary gland tissue is more resistant to chemical carcinogens than to cancer induction by radiation. The authors conclude that radiation-induced cancers in rats may develop via different pathways or from different cell populations than chemically induced cancers. (K.H.)

Susceptibility to radiation-induced mammary carcinoma in genetically resistant Copenhagen rats

Energy Technology Data Exchange (ETDEWEB)

Kamiya, Kenji; Nitta, Yumiko [Hiroshima Univ. (Japan). Research Inst. for Radiation Biology and Medicine; Gould, M.N.

2000-07-01

The objective of this experiment was to compare the cellular basis of mammary cancer induction by a chemical carcinogen with induction by ionizing radiation in three strains of rats (inbred that have different genetic susceptibilities: COP rats, F344 rats, and WF rats). Rats were given a single intraperitoneal injection of 50 mg MNU/kg body weight as a mammary-tumor-inducing chemical carcinogen and were irradiated with a 3.0 Gy dose of {sup 60} Co gamma rays at a dose rate of 26.58{+-}1.19 cGy/min. The rats were inspected weekly, and they were killed and necropsied whenever palpable tumors were detected or they became moribund. The histopathological and immunohistochemical characteristics of the mammary tumors were investigated. A transplantation experiment using selected primary mammary tumors that developed in COP rats exposed to gamma rays was also performed to investigate the transplantability of mammary tumors induced by ionizing radiation. The sensitivity of the WF and F344 rats and the resistance of the COP rats to mammary carcinoma induction by the chemical carcinogen MNU was confirmed. In contrast to the chemical carcinogens, no difference in susceptibility to radiation induction of mammary carcinomas was detected among the three strains of rats, and immunohistochemical examination indicated that the radiation-induced carcinomas consisted of more highly differentiated cells than the MNU-induced cancers. The results of the experiment appear to support the hypothesis that differentiated mammary gland tissue is more resistant to chemical carcinogens than to cancer induction by radiation. The authors conclude that radiation-induced cancers in rats may develop via different pathways or from different cell populations than chemically induced cancers. (K.H.)

Mutants of Escherichia coli K-12 with enhanced resistance to ionizing radiation

International Nuclear Information System (INIS)

Verbenko, V.N.; Akhmedov, A.T.; Kalinin, V.L.

1986-01-01

By means of one-dimensional electrophoresis, it is shown that in radiation-resistant Gam 444 ad Gam 445 mutants of Escherichia coli K-12 high-molecular weight heat shock proteins are hyperproduced at 32-37 deg C and are induced more intensively during heat shock (in comparison to the parental) wild-tupe strain AB parallel 57). When the missense htp R15 mutation of the positive regulatory htpR gene for heat shock proteins was introduced by transduction into genome of the Gam 444 mutant, its enhanced radiation-resistance disappeared but could not be restored upon introduction of pKV3 plasmid bearing the htpR, gene. These data show that heat shock Protens are participating in the enhanced radioresistance of Gam mutants

Development of EPDM based thermoplastic elastomers for oil resistant applications: optimization of radiation grafting parameters

International Nuclear Information System (INIS)

Chaudhari, C.V.; Dubey, K.A.; Bhardwaj, Y.K.; Sabharwal, S.

2008-01-01

Full text: Ethylene-propylene diene terpolymer (EPDM) is currently among the most industrially useful elastomers because of its certain unique properties like excellent heat resistance, resistance towards ozone deterioration, high impact strength. However EPDM has a serious drawback of weak adhesion properties and tendency to swell in contact with paraffin oil and aromatic hydrocarbons. Blending EPDM with suitable polar elastomers or grafting polar polymer chains onto EPDM is an easy method to overcome this drawback. Radiation grafting of Acrylonitrile (ACN) on EPDM provides an easy and effective method of incorporating ACN uniformly on the EPDM backbone. Grafting of ACN on EPDM is expected to result grafted copolymer with better oil resistance, hardness and better compatibility with polar polymer matrices. In the present study radiation induced grafting of ACN onto EPDM rubber film was investigated by mutual radiation grafting technique. Effect of experimental variables viz. radiation dose, dose rate, types of solvents and monomer content on extent of grafting was studied. The solvent composition of Acetone:CCl 4 (20:80) was found to be the optimum mixture which resulted in highest degree of grafting. It was found that the degree of grafting increases with radiation dose, monomer content and decreases with dose rate

Design and characterization of radiation resistant integrated circuits for the LHC particle detectors using deep sub-micron CMOS technologies

International Nuclear Information System (INIS)

Anelli, Giovanni Maria

2000-01-01

The electronic circuits associated with the particle detectors of the CERN Large Hadron Collider (LHC) have to work in a highly radioactive environment. This work proposes a methodology allowing the design of radiation resistant integrated circuits using the commercial sub-micron CMOS technology. This method uses the intrinsic radiation resistance of ultra-thin grid oxides, the technology of enclosed layout transistors (ELT), and the protection rings to avoid the radio-induced creation of leakage currents. In order to check the radiation tolerance level, several test structures have been designed and tested with different radiation sources. These tests have permitted to study the physical phenomena responsible for the damages induced by the radiations and the possible remedies. Then, the particular characteristics of ELT transistors and their influence on the design of complex integrated circuits has been explored. The modeling of the W/L ratio, the asymmetries (for instance in the output conductance) and the performance of ELT couplings have never been studied yet. The noise performance of the 0.25 μ CMOS technology, used in the design of several integrated circuits of the LHC detectors, has been characterized before and after irradiation. Finally, two integrated circuits designed using the proposed method are presented. The first one is an analogic memory and the other is a circuit used for the reading of the signals of one of the LHC detectors. Both circuits were irradiated and have endured very high doses practically without any sign of performance degradation. (J.S.)

Destruction of radiation-resistant cell populations by hyperthermia

International Nuclear Information System (INIS)

Roettinger, E.M.; Gerweck, L.E.

1979-01-01

Animal experiments with local hyperthermia have shown that the radiauion dose necessary for the local control of 50% of the tumours examined was essentially reduced by heating to 42,5 0 C. In-vitro experients indicated selective destruction of relatively radiation-resistent cell populations by the combination of hyperthermie and reduced hydrogen ion concentration. Experiments with glioblastoma cells confirmed these results qualitatively, but showed quantitatively considerably lower sensitivity towards hyperthermia. (orig.) 891 MG/orig. 892 RDG [de

Highly radiation-resistant vacuum impregnation resin systems for fusion magnet insulation

International Nuclear Information System (INIS)

Fabian, P.E.; Munshi, N.A.; Denis, R.J.

2002-01-01

Magnets built for fusion devices such as the newly proposed Fusion Ignition Research Experiment (FIRE) need to be highly reliable, especially in a high radiation environment. Insulation materials are often the weak link in the design of superconducting magnets due to their sensitivity to high radiation doses, embrittlement at cryogenic temperatures, and the limitations on their fabricability. An insulation system capable of being vacuum impregnated with desirable properties such as a long pot-life, high strength, and excellent electrical integrity and which also provides high resistance to radiation would greatly improve magnet performance and reduce the manufacturing costs. A new class of insulation materials has been developed utilizing cyanate ester chemistries combined with other known radiation-resistant resins, such as bismaleimides and polyimides. These materials have been shown to meet the demanding requirements of the next generation of devices, such as FIRE. Post-irradiation testing to levels that exceed those required for FIRE showed no degradation in mechanical properties. In addition, the cyanate ester-based systems showed excellent performance at cryogenic temperatures and possess a wide range of processing variables, which will enable cost-effective fabrication of new magnets. This paper details the processing parameters, mechanical properties at 76 K and 4 K, as well as post-irradiation testing to dose levels surpassing 10 8 Gy

Radiation resistance of solar cells for space application, 1

International Nuclear Information System (INIS)

Mitsui, Hiroshi; Tanaka, Ryuichi; Sunaga, Hiromi

1989-07-01

A 50-μm thick ultrathin silicon solar cell and a 280-μm thick high performance AlGaAs/GaAs solar cell with high radiation resistance have been recently developed by National Space Development Agency of Japan (NASDA). In order to study the radiation resistance of these cells, a joint research was carried out between Japan Atomic Energy Research Institute (JAERI) and NASDA from 1984 through 1987. In this research, the irradiation method of electron beams, the effects of the irradiation conditions on the deterioration of solar cells by electron beams, and the annealing effects of the radiation damage in solar cells were investigated. This paper is the first one of a series of reports of the joint research. In this paper, the space radiation environment which artificial satellites will encounter, the solar cells used, and the experimental methods are described. In addition to these, the results of the study on the irradiation procedure of electron beams are reported. In the study of the irradiation method of electron beams, three methods, that is, the fixed irradiation method, the moving irradiation method, and the spot irradiation method were examined. In the fixed irradiation method and moving one, stationary solar cells and solar cells moving by conveyer were irradiated by scanning electron beams, respectively. On the other hand, in the spot irradiation method, stationary solar cells were irradiated by non-scanning steady electron beams. It was concluded that the fixed irradiation method was the most proper method. In addition to this, in this study, some pieces of information were obtained with respect to the changes in the electrical characteristics of solar cells caused by the irradiation of electron beams. (author) 52 refs

Radiation induced structural changes in alpha-copper-zinc alloys

International Nuclear Information System (INIS)

Schuele, W.; Gieb, M.

1991-01-01

During irradiation of alpha-copper-zinc alloys with high energy electrons and protons a decrease of the electrical resistivity due to an increase of the degree of short range order is observed through radiation enhanced diffusion followed by an increase of the electrical resistivity through the formation of radiation induced interstitial clusters. The initial formation rate of interstitial clusters increases about linearly with the displacement rate for electron and proton irradiation. The largest initial formation rate is found between 60 and 130 0 C becoming negligibly small above 158 0 C and decreases drastically below 60 0 C. The dynamic steady state interstitial cluster concentration increases with decreasing irradiation temperature in the investigated temperature range between 158 and 40 0 C. Above 158 0 C the formation rate of interstitial clusters is negligibly small. Thus the transition temperature for radiation induced interstitial cluster formation is 158 0 C, depending mainly on the migration activation energy of vacancies. The radiation induced interstitial clusters are precipitates in those alloys in which the diffusion rate of the undersized component atoms via an interstitialcy diffusion mechanism is larger than that of the other atoms

Radiation resistance of quartz core fibers, (6)

International Nuclear Information System (INIS)

Suzuki, Toshiya; Morisawa, Masaaki; Gozen, Toshikazu; Tanaka, Yukihiro; Shintani, Takeshi; Okamoto, Shin-ichi.

1988-01-01

Quatz optical fibers have been used for the communication channels for long distance and large capacity, in addition, their application to the communication system in radiation environment such as nuclear power plants and artificial statellites has been positively examined. In the case of the application to aircrafts and communication satellites, optical fibers are exposed to the temperature variation of wider range than the system on the ground. Particularly, the radiation resistance of optical fibers depends largely on temperature, and at low temperature, the increase of loss is remarkable, therefore, it is important to know the characteristics in low temperature radiation environment. This time, five kinds of the core materials were prepared, and gamma-ray was irradiated at -80degC to evaluate the characteristics of increasing loss and restoration. In this report, based on the results of these evaluation, the wavelength dependence, the effect of impurities in the cores and so on are described. The absorption loss increased remarkably in short wavelength. The increase of loss in high OH fibers became high particularly in the case of low optical power. The effect of Cl was especially conspicuous in the restoration characteristics. Chlorine-free core fibers have the excellent restoration characteristics independent of wavelength and optical power. (K.I.)

Irradiation tests of radiation resistance optical fibers for fusion diagnostic application

Science.gov (United States)

Kakuta, Tsunemi; Shikama, Tatsuo; Nishitani, Takeo; Yamamoto, Shin; Nagata, Shinji; Tsuchiya, Bun; Toh, Kentaro; Hori, Junichi

2002-11-01

To promote development of radiation-resistant core optical fibers, the ITER-EDA (International Thermonuclear Experimental Reactor-Engineering Design Activity) recommended carrying out international round-robin irradiation tests of optical fibers to establish a reliable database for their applications in the ITER plasma diagnostics. Ten developed optical fibers were irradiation-tested in a Co-60 gamma cell, a Japan Materials Testing Reactor (JMTR). Also, some of them were irradiation tested in a fast neutron irradiation facility of FNS (Fast Neutron Source), especially to study temperature dependence of neutron-associated irradiation effects. Included were several Japanese fluorine doped fibers and one Japanese standard fiber (purified and undoped silica core), as well as seven Russian fibers. Some of Russian fibers were drawn by Japanese manufactures from Russian made pre-form rods to study effects of manufacturing processes to radiation resistant properties. The present paper will describe behaviors of growth of radiation-induced optical transmission loss in the wavelength range of 350-1750nm. Results indicate that role of displacement damages by fast neutrons are very important in introducing permanent optical transmission loss. Spectra of optical transmission loss in visible range will depend on irradiation temperatures and material parameters of optical fibers.

Assessment of Gamma Radiation Resistance of Spores Isolated from the Spacecraft Assembly Facility During MSL Assembly

Science.gov (United States)

Chopra, Arsh; Ramirez, Gustavo A.; Vaishampayan, Parag A.; Venkateswaran, Kasthuri J.

2011-01-01

Spore forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate extreme environmental conditions such as radiation, desiccation, and high temperatures. Since the Viking era (early 1970's), spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. There is a growing concern that desiccation and extreme radiation resistant spore forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequently proliferate on another solar body. Such forward contamination would certainly jeopardize future life detection or sample return technologies. It is important to recognize that different classes of organisms are critical while calculating the probability of contamination, and methods must be devised to estimate their abundances. Microorganisms can be categorized based on radiation sensitivity as Type A, B, C, and D. Type C represents spores resistant to radiation (10% or greater survival above 0.8 Mrad gamma radiation). To address these questions we have purified 96 spore formers, isolated during planetary protection efforts of Mars Science Laboratory assembly for gamma radiation resistance. The spores purified and stored will be used to generate data that can be used further to model and predict the probability of forward contamination.

Characteristic of resistant ionization-radiation and its relationship with polysaccharide contents in spirulina

International Nuclear Information System (INIS)

Wang Zhiping; Xu Bujin

2001-01-01

The anti-radiation capacities of intact filaments, no-sheath filaments and cells of 4 kinds of Spiralina strains (Ss-V, Sp-F, Sp-Z and Sp-D) treated by "6"0Co γ-rays were studied. The relationship between polysaccharide contents and anti-radiation capacity of 4 strains were also detected. The results showed that Spirulina is highly resistant toγ-radiation, however there were significant differences with various strains. The order of anti-radiation capacity is Ss-V > Sp-F > Sp-Z > Sp-D. Moreover, the anti-radiation capacity were remarkably related with polysaccharide contents in the 4 strains. This showed that polysaccharide is very important for raising and maintain-ing super anti-radiation capacity in Spiralina. (authors)

Radiation resistivity of quartz core fiber, 3

International Nuclear Information System (INIS)

Gozen, Toshikazu; Suzuki, Toshiya; Hayashi, Tokuji; Tanaka, Hiroyuki; Okamoto, Shinichi.

1985-01-01

Radiation resistance characteristics were evaluated for a multi-mode quartz core fiber in low temperature region together with photobleaching effect depending on the incident light power and dependency on the wavelength of measuring rays. This report describes the results of the abovementioned items and the next step study of trial manufacturing of a pure-quartz single-mode fiber for the employment of longer wavelength rays and greater capacity in light transmission communication system. Quartz core fiber specimens were irradiated by 60 Co γ-ray source at -55 deg C to 80 deg C in a constant temperature bath and light transmission loss was determined under irradiation conditions. Low temperature characteristics were superior in an MRT (modified rod-in tube) pure quartz fiber prepared by the plasma method as compared to VAD quartz and Ge-GI fibers. The MRT fiber showed better quality than the Ge-GI fiber also in the photobleaching effect examination. As for the wavelength dependency, light transmission loss of the MRT fiber was less than that of the Ge-GI fiber. The MRT fiber also showed a superior quality in the wide range of irradiation temperatures. Based on the above-mentioned understandings, a pure-quartz single-mode fiber of both BF 3 -doped and F-doped cladding types were developed for longer wavelengths uses. The fibers could attain low light transmission loss of less than 1.0 dB/km at 1.30 μm of wavelength. At the standpoint of radiation resistivity, the BF 3 -doped fiber was found superior. (Takagi, S.)

On the honeybee resistance to gamma radiation; Sur la resistance au rayonnement gamma de l'abeille ouvriere

Energy Technology Data Exchange (ETDEWEB)

Courtois, G.; Lecomte, J. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Section des Applications des Radioelements, Centre d' Etudes Nucleaires, Saclay, Station de Recherches Apicoles, Bures-sur-Yvette (France)

1960-07-01

The honeybee, when irradiated by gamma radiations from a cobalt-60 source can stand a 18000 r dose without any apparent harm. Noticeable harm is observed for 90000 r. while immediate death of 100% of the individuals is obtained with a 200000 r dose. The physiological condition of the honeybee plays an important role in its resistance to gamma radiation. Reprint of a paper published in Annales de l'abeille, IV, 1959, p. 285-290 [French] L'Abeille butineuse irradiee par le rayonnement gamma issu d'une source de Cobalt 60 supporte sans dommages apparents une dose de 18000 r. Des dommages tres appreciables sont observes pour 90000 r. Une dose de 200000 r entraine la mort immediate de 100% des individus. L'etat physiologique de l'Abeille joue un role important dans la resistance au rayonnement gamma. Reproduction d'un article publie dans Annales de l'abeille, IV, 1959, p. 285-290.

Online Simulation of Radiation Track Structure Project

Science.gov (United States)

Plante, Ianik

2015-01-01

Space radiation comprises protons, helium and high charged and energy (HZE) particles. High-energy particles are a concern for human space flight, because they are no known options for shielding astronauts from them. When these ions interact with matter, they damage molecules and create radiolytic species. The pattern of energy deposition and positions of the radiolytic species, called radiation track structure, is highly dependent on the charge and energy of the ion. The radiolytic species damage biological molecules, which may lead to several long-term health effects such as cancer. Because of the importance of heavy ions, the radiation community is very interested in the interaction of HZE particles with DNA, notably with regards to the track structure. A desktop program named RITRACKS was developed to simulate radiation track structure. The goal of this project is to create a web interface to allow registered internal users to use RITRACKS remotely.

Direction selective structural-acoustic coupled radiator

Science.gov (United States)

Seo, Hee-Seon; Kim, Yang-Hann

2005-04-01

This paper presents a method of designing a structural-acoustic coupled radiator that can emit sound in the desired direction. The structural-acoustic coupled system is consisted of acoustic spaces and wall. The wall composes two plates and an opening, and the wall separates one space that is highly reverberant and the other that is unbounded without any reflection. An equation is developed that predicts energy distribution and energy flow in the two spaces separated by the wall, and its computational examples are presented including near field acoustic characteristics. To design the directional coupled radiator, Pareto optimization method is adapted. An objective is selected to maximize radiation power on a main axis and minimize a side lobe level and a subjective is selected direction of the main axis and dimensions of the walls geometry. Pressure and intensity distribution of the designed radiator is also presented.

Radiation Resistant Hybrid Lotus Effect Photoelectrocatalytic Self-Cleaning Anti-Contamination Coatings, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — This project will develop radiation resistant hybrid Lotus Effect photoelectrocatalytic self-cleaning anti-contamination coatings for application to Lunar...

Estimation of interface resistivity in bonded Si for the development of high performance radiation detectors

International Nuclear Information System (INIS)

Kanno, Ikuo; Yamashita, Makoto; Nomiya, Seiichiro; Onabe, Hideaki

2007-01-01

For the development of high performance radiation detectors, direct bonding of Si wafers would be an useful method. Previously, p-n bonded Si were fabricated and they showed diode characteristics. The interface resistivity was, however, not investigated in detail. For the study of interface resistivity, n-type Si wafers with different resistivities were bonded. The resistivity of bonded Si wafers were measured and the interface resistivity was estimated by comparing with the results of model calculations. (author)

Radiation resistant polypropylene blended with mobilizer,. antioxidants and nucleating agent

Science.gov (United States)

Shamshad, A.; Basfar, A. A.

2000-03-01

Post-irradiation storage of medical disposables prepared from isotactic polypropylene renders them brittle due to degradation. To avoid this, isotactic polypropylene [(is)PP] was blended with a mobilizer, dioctyl pthallate (DOP), three antioxidants (hindered amines and a secondary antioxidant) and benzoic acid to obtain radiation-resistant, thermally-stable and transparent material. Different formulations prepared were subjected to gamma radiation to doses of 25 and 50 kGy. Tests of breakage on bending after ageing in an oven at 70°C up to 12 months have shown that the addition of DOP and the antioxidants imparts improved radiation and thermal stability as compared to (is)PP alone or its blend with DOP. All the formulations irradiated or otherwise demonstrated excellent colour stability even after accelerated ageing at 70°C for prolonged periods.

Radiation resistance characteristics of optical communication system for single mode

International Nuclear Information System (INIS)

Ohe, Masamoto; Chigusa, Yoshiki; Kyodo, Tomohisa; Tanaka, Gohtaro; Watanabe, Hajime; Okamoto, Shin-ichi; Yamamoto, Takao.

1988-01-01

Optical communication has been utilized also for nuclear power stations and fuel reporocessing plants. As the sufficient safety countermeasures are required there, the amount of information becomes enormous, therefore, optical communication, by which the required space is expected to be reduced, becomes more important. Also in the application to submarine cables, attention must be paid to the radiation resistance as there are the effects of potassium contained in large amount in seawater and uranium deposits in sea bottom. Therefore, the reliability of the components of optical communication systems against radiation becomes a problem. In this study, single mode optical fibers and transmission and receipt modules were selected, and high dose rate irradiation supposing the case of using in a cell and low dose rate, long time irradiation supposing the case of submarine cables were carried out to evaluate the radiation resistance characteristics. The fibers tested were SiO 2 core/F-SiO 2 clad type and GeO 2 -SiO 2 core/SiO 2 clad type. The characteristics of increasing loss in irradiation and restoration after irradiation of the former type were superior to those of the latter type. The output of a receipt module was normal during irradiation, and the output power of a transmission module decreases, but other problems did not arise. (K.I.)

Studies of the effects of ultraviolet radiation on the structural integrities of ribosomal RNA components of the Escherichia coli 50S ribosomal subunit

International Nuclear Information System (INIS)

Gorelic, L.; Parker, D.

1978-01-01

The effects of 254-nm radiation on the structural integrities of free and 50S ribosome-bound 5S and 23S ribosomal ribonucleic acids (rRNA) have been elucidated. Irradiation of aqueous solutions of Escherichia coli 50S ribosomes with 253.7-nm radiation results in the formation of single-strand breaks in double-stranded regions of the 23S rRNA component, but not in rRNA chain scission, and destabilization of the secondary structure of the 23S rRNA toward denaturation. The minimum doses of 253.7-nm radiation required for the first detection of the two effects are 7 x 10 19 quanta for the production of single-strand breaks in double-stranded regions of the 23S rRNA, and 19 quanta for destabilization of the 23S rRNA secondary structure. Free 23S rRNA is resistant toward photoinduced chain breakage at doses of 253.7-nm radiation up to at least 2.3 x 10 20 and is much less sensitive toward destabilization of secondary structure than ribosome-bound 23S rRNA. In contrast to the photosensitivity of 50S ribosome-bound 23S rRNA toward chain breakage, 50S ribosome-bound 5S rRNA is resistant toward chain breakage at doses of 253.7-nm radiation up to at least 2.3 x 10 20 quanta. Ribosome-bound 5S and 23S rRNA are also not photosensitive toward intermolecular 5S/23S rRNA cross-linkage

Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance, EMI shielding, and high impact resistance are...

Ultra-Lightweight Nanocomposite Foams and Sandwich Structures for Space Structures Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Space structures that are ultra-lightweight, and have gas barrier property, space durability, radiation resistance and high impact resistance are desirable to...

Fiber structural analysis by synchrotron radiation

CERN Document Server

Kojima, J I; Kikutani, T

2003-01-01

Topics of fiber structural analysis by synchrotron radiation are explained. There are only three synchrotron radiation facilities in the world, SPring-8 (Super Photon ring-8) in Japan, APS (Advanced Photon Source) in U.S.A. and ESRF (European Synchrotron Radiation Facility) in France. Online measurement of melt spinning process of PET and Nylon6 is explained in detail. Polypropylene and PBO (poly-p-phenylenebenzobisoxazole) was measured by WAXD (Wide Angle X-ray Diffraction)/SAXS (Small Angle X-ray Scattering) at the same time. Some examples of measure of drawing process of fiber are described. The structure formation process of spider's thread was measured. Micro beam of X-ray of synchrotron facility was improved and it attained to 65nm small angle resolving power by 10 mu m beamsize. (S.Y.)

Radiation effects in fine metal media

International Nuclear Information System (INIS)

Zaikin, Yu. A.; Aliev, A.B.

1999-01-01

The report discusses condition and perspectives of theoretical and experimental research of metal powder material radiation processing influence on their caking, recrystallization and formation of metal and alloy structure obtained by powder metallurgy methods. Radiation processing of metal powders under determined modes causes forming of homogeneous fine metal structure and helps to considerably improve their running abilities (strength, endurance, corrosion resistance) and caking technological conditions

Radiation damage resistance in mercuric iodide X-ray detectors

Energy Technology Data Exchange (ETDEWEB)

Patt, B E; Dolin, R C; Devore, T M; Markakis, J M [EG and G Energy Measurements, Inc., Goleta, CA (USA); Iwanczyk, J S; Dorri, N [Xsirius, Inc., Marina del Rey, CA (USA); Trombka, J [National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center

1990-12-20

Mercuric iodide (HgI{sub 2}) radiation detectors show great potential as ambient-temperature solid-state detectors for X-rays, gamma rays and visible light, with parameters that are competitive with existing technologies. In a previous experiment, HgI{sub 2} detectors irradiated with 10 MeV protons/cm{sup 2} exhibited no damage. The 10 MeV protons represent only the low range of the spectrum of energies that are important. An experiment has been conducted at the Saturne accelerator facility at Saclay, France, to determine the susceptibility of these detectors to radiation damage by high-energy (1.5 GeV) protons. The detectors were irradiated to a fluence of 10{sup 8} protons/cm{sup 2}. This fluence is equivalent to the cosmic radiation expected in a one-year period in space. The resolution of the detectors was measured as a function of the integral dose. No degradation in the response of any of the detectors or spectrometers was seen. It is clear from this data that HgI{sub 2} has extremely high radiation-damage resistance, exceeding that of most other semiconductor materials used for radiation detectors. Based on the results shown to date, HgI{sub 2} detectors are suitable for applications in which they may be exposed to high integral dose levels. (orig.).

Atomistic simulations of the radiation resistance of oxides

International Nuclear Information System (INIS)

Chartier, A.; Van Brutzel, L.; Crocombette, J.-P.

2012-01-01

Fluorite compounds such as urania and ceria, or related compounds such as pyrochlores and also spinels show different behaviors under irradiations, which ranges from perfect radiation resistance to crystalline phase change or even complete amorphization depending on their structure and/or their composition. Displacement cascades – dedicated to the understanding of the ballistic regime and performed by empirical potentials molecular dynamics simulations – have revealed that the remaining damages of the above mentioned oxides are reduced to point defects unlike what is observed in zircon and zirconolite, which directly amorphize during the cascade. The variable behavior of these point defects is the key of the various responses of these materials to irradiations. This behavior can be investigated by two specific molecular dynamics methodologies that will be reviewed here: (i) the method of point defects accumulation as a function of temperature that gives access to the dose effects and to the critical doses for amorphization; (ii) the study Frenkel pairs life-time – i.e. their time of recombination as function of temperature – that may be used as a tool to understand the results obtained in displacements cascades or to identify the microscopic mechanisms responsible for the amorphization/re-crystallization during the point defects accumulations.

Radiation resistance in mice increased following chronic application of Li/sub 2/CO/sub 3/

Energy Technology Data Exchange (ETDEWEB)

Vacek, A.; Sikulova, J.; Bartonickova, A. (Ceskoslovenska Akademie Ved, Brno. Biofysikalni Ustav)

1982-01-01

In experiments on strain H mice the increased radiation resistance of mice was analysed after three weeks' feeding with a diet including Li given as lithium carbonicum. The concentration of Li in the serum during the first three days of feeding was increased to 0.5 mmol/l and remained at that level to the end of feeding. The application of Li increased the overall number of stem cells in the spleen by 80 per cent compared with the control group. D/sub 0/ of the line of dependence of the number of endogenous colonies on radiation dose increased following Li application by 1.2 Gy compared with controls. The proliferation activity of haemopoietic stem cells observed 90 min after injection of hydroxyurea was, after 21 days feeding with a mixture containing Li, increased by 200 per cent. The results support the idea that the increased radiation resistance of mice following feeding with Li salts before irradiation may be due to the increased content and resistance of the haemopoietic stem cells, as well as activation of granulopoiesis.

Mechanisms of UVB-resistance in rice: Cultivar differences in the sensitivity to UVB radiation in rice

International Nuclear Information System (INIS)

Hidema, J.

2001-01-01

In a study on the sensitivity to UVB radiation of rice cultivars of 5 Asian rice ecotypes, results showed that the rice cultivars widely varied in UVB sensitivity; among the Japanese rice cultivars, Sasanishiki was more resistant to UVB, while Norin 1 was less resistant; UV-sensitive Norin 1 was deficient in photorepair of cyclobutane pyrimidine dimers (UV-induced DNA damage), and the sensitivity to UVB radiation significantly correlated with deficient CPD photorepair; and that this deficiency in Norin 1 resulted from a functionally altered photolyase. The results suggest that photorepair capacity is a principal factor in determining UVB sensitivity in rice. The effects of supplemental UVB radiation on the growth and yield of Japanese rice cultivars under field conditions were also studied in Japan since 1993. The results indicate that supplemental UVB radiation had inhibitory effects on the growth and yield of rice. Furthermore, grain size was smaller with supplemental UVB radiation

Induction of radiation resistance and radio-protective mechanism. On the reactive oxygen and free radical

International Nuclear Information System (INIS)

Yukawa, Osami

2003-01-01

Radical scavenging system for reactive oxygen species (ROS) leading to radio-protection is reviewed on findings in animals, tissues and cells. Protection against oxygen toxicity in evolution can be seen in anaerobes' superoxide dismutase (SOD) over 3500 million years ago. ROS is generated endogenously and also by radiation. However, the intracellular sites of the generated ROS are different depending on its cause. The protection is done through enzymes like SOD, peroxidase, catalase, glutathione-related enzymes and through substances like GSH, α-tocopherol, ascorbic acid etc. Induction of ROS scavenging substances related with radio-resistance includes the responses to the low dose radiation (5-50 cGy) in those enzymes described above; to middle to high dose radiation (1-30 Gy) in a similar and in other unknown mechanisms; to exposure of ROS like H 2 O 2 at low concentration; and to antioxidant treatment. The cross-resistance between radiation and drugs suggests necessity of this induction. (N.I.)

Acquired Tumor Cell Radiation Resistance at the Treatment Site Is Mediated Through Radiation-Orchestrated Intercellular Communication

Energy Technology Data Exchange (ETDEWEB)

Aravindan, Natarajan, E-mail: naravind@ouhsc.edu [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Aravindan, Sheeja; Pandian, Vijayabaskar; Khan, Faizan H.; Ramraj, Satish Kumar; Natt, Praveen [Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma (United States); Natarajan, Mohan [Department of Pathology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas (United States)

2014-03-01

Purpose: Radiation resistance induced in cancer cells that survive after radiation therapy (RT) could be associated with increased radiation protection, limiting the therapeutic benefit of radiation. Herein we investigated the sequential mechanistic molecular orchestration involved in radiation-induced radiation protection in tumor cells. Results: Radiation, both in the low-dose irradiation (LDIR) range (10, 50, or 100 cGy) or at a higher, challenge dose IR (CDIR), 4 Gy, induced dose-dependent and sustained NFκB-DNA binding activity. However, a robust and consistent increase was seen in CDIR-induced NFκB activity, decreased DNA fragmentation, apoptosis, and cytotoxicity and attenuation of CDIR-inhibited clonal expansion when the cells were primed with LDIR prior to challenge dose. Furthermore, NFκB manipulation studies with small interfering RNA (siRNA) silencing or p50/p65 overexpression unveiled the influence of LDIR-activated NFκB in regulating CDIR-induced DNA fragmentation and apoptosis. LDIR significantly increased the transactivation/translation of the radiation-responsive factors tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), cMYC, and SOD2. Coculture experiments exhibit LDIR-influenced radiation protection and increases in cellular expression, secretion, and activation of radiation-responsive molecules in bystander cells. Individual gene-silencing approach with siRNAs coupled with coculture studies showed the influence of LDIR-modulated TNF-α, IL-1α, cMYC, and SOD2 in induced radiation protection in bystander cells. NFκB inhibition/overexpression studies coupled with coculture experiments demonstrated that TNF-α, IL-1α, cMYC, and SOD2 are selectively regulated by LDIR-induced NFκB. Conclusions: Together, these data strongly suggest that scattered LDIR-induced NFκB-dependent TNF-α, IL-1α, cMYC, and SOD2 mediate radiation protection to the subsequent challenge dose in tumor cells.

Assessment of the role of oxygen and mitochondria in heat shock induction of radiation and thermal resistance in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Mitchel, R.E.J.; Morrison, D.P.

1983-01-01

In response to a heat shock, the yeast Saccharomyces cerevisiae undergoes a large increase in its resistance to heat and, by the induction of its recombinational DNA repair capacity, a corresponding increase in resistance to radiation. Yeast which lack mitochondrial DNA, mitochondria-controlled protein synthetic apparatus, aerobic respiration, and electron transport (rho 0 strain) were used to assess the role of O 2 , mitochondria, and oxidative processes controlled by mitochondria in the induction of these resistances. We have found that rho 0 yeast grown and heat shocked in either the presence or absence of O 2 are capable of developing both radiation and heat resistance. We conclude that neither the stress signal nor its cellular consequences of induced heat and radiation resistance are directly dependent on O 2 , mitochondrial DNA, or mitochondria-controlled protein synthetic or oxidative processes

Molecular exploration of the highly radiation resistant cyanobacterium Arthrospira sp. PCC 8005

Science.gov (United States)

Badri, Hanène; Leys, Natalie; Wattiez, Ruddy

Arthrospira (Spirulina) is a photosynthetic cyanobacterium able to use sunlight to release oxygen from water and remove carbon dioxide and nitrate from water. In addition, it is suited for human consumption (edible). For these traits, the cyanobacterium Arthrospira sp. PCC 8005 was selected by the European Space Agency (ESA) as part of the life support system MELiSSA for recycling oxygen, water, and food during future long-haul space missions. However, during such extended missions, Arthrospira sp. PCC 8005 will be exposed to continuous artificial illumination and harmful cosmic radiation. The aim of this study was to investigate how Arthrospira will react and behave when exposed to such stress environment. The cyanobacterium Arthrospira sp. PCC 8005 was exposed to high gamma rays doses in order to unravel in details the response of this bacterium following such stress. Test results showed that after acute exposure to high doses of 60Co gamma radiation upto 3200 Gy, Arthrospira filaments were still able to restart photosynthesis and proliferate normally. Doses above 3200 Gy, did have a detrimental effect on the cells, and delayed post-irradiation proliferation. The photosystem activity, measured as the PSII quantum yield immediately after irradiation, decreased significantly at radiation doses above 3200 Gy. Likewise through pigment content analysis a significant decrease in phycocyanin was observed following exposure to 3200 Gy. The high tolerance of this bacterium to 60Co gamma rays (i.e. ca. 1000x more resistant than human cells for example) raised our interest to investigate in details the cellular and molecular mechanisms behind this amazing resistance. Optimised DNA, RNA and protein extraction methods and a new microarray chip specific for Arthrospira sp. PCC 8005 were developed to identify the global cellular and molecular response following exposure to 3200 Gy and 5000 Gy A total of 15,29 % and 30,18 % genes were found differentially expressed in RNA

How the nature of the chemical bond governs resistance to amorphization by radiation damage

International Nuclear Information System (INIS)

Trachenko, Kostya; Artacho, Emilio; Dove, Martin T.; Pruneda, J.M.

2005-01-01

We discuss what defines a material's resistance to amorphization by radiation damage. We propose that resistance is generally governed by the competition between the short-range covalent and long-range ionic forces, and we quantify this picture using quantum-mechanical calculations. We calculate the Voronoi deformation density charges and Mulliken overlap populations of 36 materials, representative of different families, including complex oxides. We find that the computed numbers generally follow the trends of experimental resistance in several distinct families of materials: the increase (decrease) of the short-range covalent component in material's total force field decreases (increases) its resistance

Comparison Study On Sunlight Or Gamma Radiation Aging Resistance Of Poly (Vinyl Pyrrolidone) Aqueous Solution With PVP Nanogel

International Nuclear Information System (INIS)

Doan Binh; Pham Thu Hong; Nguyen Nguyet Dieu; Nguyen Thanh Duoc

2011-01-01

Comparison study on sunlight or gamma-radiation aging resistance of poly (vinyl pyrrolidone) (PVP) aqueous solution with PVP nanogel at 0.5% was carried out. Sunlight or gamma- radiation aging resistance of PVP aqueous solution and nanogel was evaluated on the basis of their intrinsic viscosity, UV-VIS absorbance, weight averaged molecular weight (M w ). The PVP aqueous solution and nanogel exposed to sunlight in the storage duration of 3 months and to gamma radiation at absorbed doses of 0, 15, 30, 50 kGy were used for this study. Furthermore, the stability of PVP nanogel and of PVP aqueous solution was also studied on the change of their intrinsic viscosity, UV-VIS absorbance, weight averaged molecular weight, particle size distribution and coil size. The experimental results were shown that the aging resistance of PVP nanogel was higher than that of PVP aqueous solution when exposed to gamma radiation or sunlight. (author)

Effect of nano-oxide particle size on radiation resistance of iron–chromium alloys

Energy Technology Data Exchange (ETDEWEB)

Xu, Weizong; Li, Lulu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Valdez, James A. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Saber, Mostafa [Department of Mechanical and Materials Engineering, Portland State University, Portland, OR 97201 (United States); Zhu, Yuntian, E-mail: ytzhu@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Koch, Carl C.; Scattergood, Ronald O. [Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695 (United States)

2016-02-15

Radiation resistance of Fe–14Cr alloys under 200 keV He irradiation at 500 °C was systematically investigated with varying sizes of nano oxide Zr, Hf and Cr particles. It is found that these nano oxide particles acted as effective sites for He bubble formation. By statistically analyzing 700–1500 He bubbles at the depth of about 150–700 nm from a series of HRTEM images for each sample, we established the variation of average He bubble size, He bubble density, and swelling percentage along the depth, and found them to be consistent with the He concentration profile calculated from the SIRM program. Oxide particles with sizes less than 3.5–4 nm are found most effective for enhancing radiation resistance in the studied alloy systems.

Concomitant changes in radiation resistance and trehalose levels during life stages of Drosophila melanogaster suggest radio-protective function of trehalose.

Science.gov (United States)

Paithankar, Jagdish Gopal; Raghu, Shamprasad Varija; Patil, Rajashekhar K

2018-04-20

During development, various life stages of Drosophila melanogaster (D. melanogaster) show different levels of resistance to gamma irradiation, with the early pupal stage being the most radiation sensitive. This provides us an opportunity to explore the biochemical basis of such variations. The present study was carried out to understand the mechanisms underlying radiation resistance during life stages of D. melanogaster. Homogenates from all the life stages of D. melanogaster were prepared at stipulated age. These homogenates were used for the determination of (1) enzymatic antioxidants: superoxide dismutase (SOD), catalase, D. melanogaster glutathione peroxidase (DmGPx), and glutathione S-transferase (GST); (2) reducing non-enzymatic antioxidants: total antioxidant capacity (TAC), reduced glutathione (GSH) and non-reducing non-enzymatic antioxidant trehalose; and (3) levels of protein carbonyl (PC) content. Age-dependent changes in radiation resistance and associated biochemical changes were also studied in young (2 d) and old (20 and 30 d) flies. TAC and GSH were found high in the early pupal stage, whereas catalase and DmGPx were found to increase in the early pupal stage. The non-feeding third instar (NFTI) larvae were found to have high levels of SOD and GST, besides NFTI larvae showed high levels of trehalose. A remarkable decrease was observed in radiation resistance and trehalose levels during the early pupal stage. The PC level was the highest during early pupal stage and was the lowest in NFTI larvae. Older flies showed high level of PC compared with young flies. In vitro increments in trehalose concentration correspond to reduced formation of PCs, suggesting a protective role of trehalose against free radicals. A strong correlation between levels of trehalose and PC formation suggests amelioration of proteome damage due to ionizing radiation (IR). Stages with high trehalose levels showed protected proteome and high radiation resistance, suggesting a

Propagation of synchrotron radiation through nanocapillary structures

International Nuclear Information System (INIS)

Bjeoumikhov, A.; Bjeoumikhova, S.; Riesemeier, H.; Radtke, M.; Wedell, R.

2007-01-01

The propagation of synchrotron radiation through nanocapillary structures with channel sizes of 200 nm and periods in the micrometer size has been studied experimentally. It was shown that the propagation through individual capillary channels has a mode formation character. Furthermore it was shown that during the propagation through capillary channels the coherence of synchrotron radiation is partially conserved. Interference of beams propagating through different capillary channels is observed which leads to a periodically modulated distribution of the radiation intensity in a plane far from the exit of the structure. These investigations are of high relevance for the understanding of X-ray transmission through nanocapillaries and the appearance of wave properties at this size scale

Analysis of interface states and series resistance at MIS structure irradiated under {sup 60}Co {gamma}-rays

Energy Technology Data Exchange (ETDEWEB)

Tataroglu, A. [Department of Physics, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey)], E-mail: ademt@gazi.edu.tr; Altindal, S. [Department of Physics, Faculty of Arts and Sciences, Gazi University, 06500 Ankara (Turkey)

2007-10-11

In this research, we investigated the effect of {sup 60}Co {gamma}-ray exposure on the electrical properties of Au/SnO{sub 2}/n-Si (MIS) structures using current-voltage (I-V) measurements. The fabricated devices were exposed to {gamma}-ray doses ranging from 0 to 300 kGy at a dose rate of 2.12 kGy h{sup -1} in water at room temperature. The density of interface states N{sub ss} as a function of E{sub c}-E{sub ss} is deduced from the forward bias I-V data for each dose by taking into account the bias dependence effective barrier height and series resistance of device at room temperature. Experimental results show that the {gamma}-irradiation gives rise to an increase in the zero bias barrier height {phi}{sub BO}, as the ideality factor n and N{sub ss} decrease with increasing radiation dose. In addition, the values of series resistance were determined using Cheung's method. The R{sub s} increases with increasing radiation dose. The results show that the main effect of the radiation is the generation of interface states with energy level within the forbidden band gap at the insulator/semiconductor interface.

Radiation induction of drug resistance in RIF-1 tumors and tumor cells

International Nuclear Information System (INIS)

Hopwood, L.E.; Moulder, J.E.

1989-01-01

The RIF-1 tumor cell line contains a small number of cells (1-20 per 10(6) cells) that are resistant to various single antineoplastic drugs, including 5-fluorouracil (5FU), methotrexate (MTX), and adriamycin (ADR). For 5FU the frequency of drug resistance is lower for tumor-derived cells than for cells from cell culture; for MTX the reverse is true, and for ADR there is no difference. In vitro irradiation at 5 Gy significantly increased the frequency of drug-resistant cells for 5FU, MTX, and ADR. In vivo irradiation at 3 Gy significantly increased the frequency of drug-resistant cells for 5FU and MTX, but not for ADR. The absolute risk for in vitro induction of MTX, 5FU, and ADR resistance, and for in vivo induction of 5FU resistance, was 1-3 per 10(6) cells per Gy; but the absolute risk for in vivo induction of MTX resistance was 54 per 10(6) cells per Gy. The frequency of drug-resistant cells among individual untreated tumors was highly variable; among individual irradiated tumors the frequency of drug-resistant cells was significantly less variable. These studies provide supporting data for models of the development of tumor drug resistance, and imply that some of the drug resistance seen when chemotherapy follows radiotherapy may be due to radiation-induced drug resistance

Sensitivity to ionizing radiation and chemotherapeutic agents in gemcitabine-resistant human tumor cell lines

International Nuclear Information System (INIS)

Bree, Chris van; Kreder, Natasja Castro; Loves, Willem J.P.; Franken, Nicolaas A.P.; Peters, Godefridus J.; Haveman, Jaap

2002-01-01

Purpose: To determine cross-resistance to anti-tumor treatments in 2',2'difluorodeoxycytidine (dFdC, gemcitabine)-resistant human tumor cells. Methods and Materials: Human lung carcinoma cells SW-1573 (SWp) were made resistant to dFdC (SWg). Sensitivity to cisplatin (cDDP), paclitaxel, 5-fluorouracil (5-FU), methotrexate (MTX), cytarabine (ara-C), and dFdC was measured by a proliferation assay. Radiosensitivity and radioenhancement by dFdC of this cell panel and the human ovarian carcinoma cell line A2780 and its dFdC-resistant variant AG6000 were determined by clonogenic assay. Bivariate flowcytometry was performed to study cell cycle changes. Results: In the SWg, a complete deoxycytidine kinase (dCK) deficiency was found on mRNA and protein level. This was accompanied by a 10-fold decrease in dCK activity which resulted in the >1000-fold resistance to dFdC. Sensitivity to other anti-tumor drugs was not altered, except for ara-C (>100-fold resistance). Radiosensitivity was not altered in the dFdC-resistant cell lines SWg and AG6000. High concentrations (50-100 μM dFdC) induced radioenhancement in the dFdC-resistant cell lines similar to the radioenhancement obtained at lower concentrations (10 nM dFdC) in the parental lines. An early S-phase arrest was found in all cell lines after dFdC treatment where radioenhancement was achieved. Conclusions: In the dFdC-resistant lung tumor cell line SWg, the deficiency in dCK is related to the resistance to dFdC and ara-C. No cross-resistance was observed to other anti-tumor drugs used for the treatment in lung cancer. Sensitivity to ionizing radiation was not altered in two different dFdC-resistant cell lines. Resistance to dFdC does not eliminate the ability of dFdC to sensitize cells to radiation

Radiation-hard ceramic Resistive Plate Chambers for forward TOF and T0 systems

Energy Technology Data Exchange (ETDEWEB)

Akindinov, A., E-mail: Alexander.Akindinov@cern.ch [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Dreyer, J.; Fan, X.; Kämpfer, B. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Kiselev, S. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Kotte, R.; Garcia, A. Laso [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Malkevich, D. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Naumann, L. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Nedosekin, A.; Plotnikov, V. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation); Stach, D. [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Sultanov, R.; Voloshin, K. [Institute for Theoretical and Experimental Physics, Moscow (Russian Federation)

2017-02-11

Resistive Plate Chambers with ceramic electrodes are the main candidates for a use in precise multi-channel timing systems operating in high-radiation conditions. We report the latest R&D results on these detectors aimed to meet the requirements of the forward T0 counter at the CBM experiment. RPC design, gas mixture, limits on the bulk resistivity of ceramic electrodes, efficiency, time resolution, counting rate capabilities and ageing test results are presented.

Toward advanced gamma rays radiation resistance and shielding efficiency with phthalonitrile resins and composites

Science.gov (United States)

Derradji, Mehdi; Zegaoui, Abdeldjalil; Xu, Yi-Le; Wang, An-ran; Dayo, Abdul Qadeer; Wang, Jun; Liu, Wen-bin; Liu, Yu-Guang; Khiari, Karim

2018-04-01

The phthalonitrile resins have claimed the leading place in the field of high performance polymers thanks to their combination of outstanding properties. The present work explores for the first time the gamma rays radiation resistance and shielding efficiency of the phthalonitrile resins and its related tungsten-reinforced nanocomposites. The primary goal of this research is to define the basic behavior of the phthalonitrile resins under highly ionizing gamma rays. The obtained results confirmed that the neat phthalonitrile resins can resist absorbed doses as high as 200 kGy. Meanwhile, the remarkable shielding efficiency of the phthalonitrile polymers was confirmed to be easily improved by preparing lead-free nanocomposites. In fact, the gamma rays screening ratio reached the exceptional value of 42% for the nanocomposites of 50 wt% of nano-tungsten loading. Thus, this study confirms that the remarkable performances of the phthalonitrile resins are not limited to the thermal and mechanical properties and can be extended to the gamma rays radiation and shielding resistances.

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

International Nuclear Information System (INIS)

Shimizu, Takashi; Ichikawa, Tsuneki

2005-01-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon γ-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M n R 1 COOCH(C 6 H 5 )R 2 M n +e - ->M n R 1 COO - + · CH(C 6 H 5 )R 2 M n . The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching

Radiation damage studies of nuclear structural materials

International Nuclear Information System (INIS)

Barat, P.

2012-01-01

Maximum utilization of fuel in nuclear reactors is one of the important aspects for operating them economically. The main hindrance to achieve this higher burnups of nuclear fuel for the nuclear reactors is the possibility of the failure of the metallic core components during their operation. Thus, the study of the cause of the possibility of failure of these metallic structural materials of nuclear reactors during full power operation due to radiation damage, suffered inside the reactor core, is an important field of studies bearing the basic to industrial scientific views.The variation of the microstructure of the metallic core components of the nuclear reactors due to radiation damage causes enormous variation in the structure and mechanical properties. A firm understanding of this variation of the mechanical properties with the variation of microstructure will serve as a guide for creating new, more radiation-tolerant materials. In our centre we have irradiated structural materials of Indian nuclear reactors by charged particles from accelerator to generate radiation damage and studied the some aspects of the variation of microstructure by X-ray diffraction studies. Results achieved in this regards, will be presented. (author)

Up-regulation of DNA-dependent protein kinase correlates with radiation resistance in oral squamous cell carcinoma

International Nuclear Information System (INIS)

Shintani, Satoru; Mihara, Mariko; Li, Chunnan; Nakahara Yuuji; Hino, Satoshi; Nakashiro, Koh-ichi; Hamakawa, Hiroyuki

2003-01-01

DNA-PK is a nuclear protein with serine/threonine kinase activity and forms a complex consisting of the DNA-PKcs and a heterodimer of Ku70 and Ku80 proteins. Recent laboratory experiments have demonstrated that the DNA-PK complex formation is one of the major pathways by which mammalian cells respond to DNA double-strand breaks induced by ionizing radiation. In this study, we evaluated the relationship between expression levels of DNA-PKcs, Ku70 and Ku80 proteins and radiation sensitivity in oral squamous cell carcinoma (OSCC) cell lines and in OSCC patients treated with preoperative radiation therapy. The OSCC cell lines greatly differed in their response to irradiation, as assessed by a standard colony formation assay. However, the expression levels of the DNA-PK complex proteins were all similar, and there was no association between the magnitude of their expression and the tumor radiation sensitivity. Expression of DNA-PK complex proteins increased after radiation treatment, and the increased values correlated with the tumor radiation resistance. Expression of DNA-PKcs and Ku70 after irradiation was increased in the surviving cells of OSCC tissues irradiated preoperatively. These results suggest that up-regulation of DNA-PK complex protein, especially DNA-PKcs, after radiation treatment correlates to radiation resistance. DNA-PKcs might be a molecular target for a novel radiation sensitization therapy of OSCC. (author)

Synchrotron radiation: a new perspectives for structure examinations

International Nuclear Information System (INIS)

Kadyrzhanov, K.K.; Kozhakhmetov, S.K.; Turkebaev, T.Eh.

2001-01-01

An important task of radiation material testing is manufacture of multifunctional, stable and cheap materials with designed properties. A materials successful operation in an extemal conditions (high temperatures and pressures, high radiation fluences and charged particles, and etc.) imply an joint decision of physical, chemical, mechanical and other problems. The decision of these problems includes at least examination for structural, phase content, oxidation stability, thermal stability, mechanical strength, thin-film-coverings controlled synthesis (both the passivating and the catalytic) compatible with main matrix, and etc. Synchrotron radiation sources application for these problems are highly perspective. Solution of a set of problems on structural examinations for a materials exposed to high radiation fluences and operating in extemal condition is planning with use of the DELSY third generation synchrotron radiation source constructing at the Joint Institute for Nuclear Research (Dubna). In the paper the principal parameters of the DELSY synchrotron radiation source are given

Radiation Resistance and Gain of Homogeneous Ring Quasi-Array

DEFF Research Database (Denmark)

Knudsen, H. L.

1954-01-01

In a previous paper homogeneous ring quasi-arrays of tangential or radial dipoles were introduced, i.e. systems of dipoles arranged equidistantly along a circle, the dipoles being oriented in tangential or radial directions and carrying currents with the same amplitude, but with a phase that incr......In a previous paper homogeneous ring quasi-arrays of tangential or radial dipoles were introduced, i.e. systems of dipoles arranged equidistantly along a circle, the dipoles being oriented in tangential or radial directions and carrying currents with the same amplitude, but with a phase...... that increases uniformly along the circle. Such quasi-arrays are azimuthally omnidirectional, and the radiated field will be mainly horizontally polarized and concentrated around the plane of the circle. In this paper expressions are obtained for the radiation resistance and the gain of homogeneous ring quasi...

Radiation resistance of electro-optic polymer-based modulators

International Nuclear Information System (INIS)

Taylor, Edward W.; Nichter, James E.; Nash, Fazio D.; Haas, Franz; Szep, Attila A.; Michalak, Richard J.; Flusche, Brian M.; Cook, Paul R.; McEwen, Tom A.; McKeon, Brian F.; Payson, Paul M.; Brost, George A.; Pirich, Andrew R.; Castaneda, Carlos; Tsap, Boris; Fetterman, Harold R.

2005-01-01

Mach-Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation

Radiation induced nano structures

International Nuclear Information System (INIS)

Ibragimova, E.M.; Kalanov, M.U.; Khakimov, Z.

2006-01-01

Full text: Nanometer-size silicon clusters have been attracting much attention due to their technological importance, in particular, as promising building blocks for nano electronic and nano photonic systems. Particularly, silicon wires are of great of interest since they have potential for use in one-dimensional quantum wire high-speed field effect transistors and light-emitting devices with extremely low power consumption. Carbon and metal nano structures are studied very intensely due to wide possible applications. Radiation material sciences have been dealing with sub-micron objects for a long time. Under interaction of high energy particles and ionizing radiation with solids by elastic and inelastic mechanisms, at first point defects are created, then they form clusters, column defects, disordered regions (amorphous colloids) and finally precipitates of another crystal phase in the matrix. Such irradiation induced evolution of structure defects and phase transformations was observed by X-diffraction techniques in dielectric crystals of quartz and corundum, which exist in and crystal modifications. If there is no polymorphism, like in alkali halide crystals, then due to radiolysis halogen atoms are evaporated from the surface that results in non-stoichiometry or accumulated in the pores formed by metal vacancies in the sub-surface layer. Nano-pores are created by intensive high energy particles irradiation at first chaotically and then they are ordered and in part filled by inert gas. It is well-known mechanism of radiation induced swelling and embrittlement of metals and alloys, which is undesirable for construction materials for nuclear reactors. Possible solution of this problem may come from nano-structured materials, where there is neither swelling nor embrittlement at gas absorption due to very low density of the structure, while strength keeps high. This review considers experimental observations of radiation induced nano-inclusions in insulating

Dichromatic and monochromatic laser radiation effects on antibiotic resistance, biofilm formation, and division rate of Pantoea agglomerans

Science.gov (United States)

Thomé, A. M. C.; Souza, B. P.; Mendes, J. P. M.; Cardoso, A. F. R.; Soares, L. C.; Trajano, E. T. L.; Fonseca, A. S.

2018-06-01

Since infection is a common cause of delayed wound healing, it is important to understand the effect of low-level laser therapy (LLLT) in bacterial mechanisms. In this study we evaluated the effects of LLLT on antibiotic resistance, division rate, and biofilm formation of Pantoea agglomerans. P. agglomerans samples were isolated from human pressure injuries in humans and cultures were exposed to low-level monochromatic and simultaneous dichromatic laser radiation to study the susceptibility of an antimicrobial to ampicillin and piperacillin  +  tazobactam, quantification of areas of bacterial colonies, and biofilm formation of bacterial cells. Fluence, wavelength, and emission mode were used in the therapeutic protocols for wound healing. The data showed no changes in the areas of the colonies, but dichromatic laser radiation decreased biofilm formation, while a monochromatic red laser at low dose increased biofilm formation and infrared at high dose decreased antibiotic resistance to ampicillin. LLLT modulates antibiotic resistance and biofilm formation of P. agglomerans, but these depend on the laser irradiation parameters, since dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation. Thus, simultaneous dichromatic low-level red and infrared lasers could be a new option for the treatment of infected wounds, reducing biofilm formation, without altering antibiotic resistance and the division rate of P. agglomerans cultures.

Resistance to fracture of carbon weldable structural steel with ferrite-pearlite and widmanstaetten structure

International Nuclear Information System (INIS)

Gulyaev, A.P.; Guzovskaya, M.A.

1977-01-01

Consideration is given to mechanical properties of St3 steel with varying ferritic-peartilic and widmanstaetten structures typical of a weld seam and adjacent zones. It has been found that mechanical properties determined at static tension are sensitive to structure variation in the limits under study. A considerable difference has been detected during impact tests CT 50 , asub(p)). The highest resistance to breakage is observed for the steel with a fine-grain ferritic-pearlitic structure (T 50 =-10 deg C, asub(p)=4.3 kgxm/cm 2 ). The enlargement of such a structure enhances transition temperature (T 50 =+20 deg C) and reduces resistance to crack development (asub(p)2.4 kgxm/cm 2 ). The appearance of widmanstaetten zones in the fine-grain structure leads also to a higher T 50 , up to +10 deg C, and at a completely widmanstaetten structure T 50 =+25 deg C. An especially unfavorable effect on the resistance of steel to breakage is produced by structure nonuniformity, i.e. accumulation of loop-like pearlitic and ferritic zones

Functional genetic research for radiation and drug resistant adenocarcinoma and its application

Energy Technology Data Exchange (ETDEWEB)

Kim, In Gyu; Kim, Kug Chan; Jung, Il Lae; Chul, Shin Byung; Kook, Park Hyo; Lee, Hee Min

2012-01-15

The work scope of 'Functional genetic research for radiation and drug resistant adenocarcinoma and its application' had contained the research about effect of transgelin(SM22a), neurotensin, metallothionein-1G transgelin-2 genes on the cell death triggered ionizing radiation, cisplatin, MMS, luteolin and H{sub 2}O{sub 2}(toxic agents), which are highly expressed in radiation-induced mutant cells. In this study, to elucidate the role of these proteins in the ionizing radiation (toxic chemicals)-induced cell death, we utilized sensed (or antisense, small interference RNA) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation, H{sub 2}O{sub 2} and toxic chemicals. We also investigated the functions of downstream target genes of transgelin such as IGF-1Rβ/PI3K/AKT pathway and transgelin/metallothioneine in A-549 and HepG2 cells because such target genes are able to potentiate the cell-killing or cell protecting effects against radiation.

Functional genetic research for radiation and drug resistant adenocarcinoma and its application

International Nuclear Information System (INIS)

Kim, In Gyu; Kim, Kug Chan; Jung, Il Lae; Chul, Shin Byung; Kook, Park Hyo; Lee, Hee Min

2012-01-01

The work scope of 'Functional genetic research for radiation and drug resistant adenocarcinoma and its application' had contained the research about effect of transgelin(SM22a), neurotensin, metallothionein-1G transgelin-2 genes on the cell death triggered ionizing radiation, cisplatin, MMS, luteolin and H 2 O 2 (toxic agents), which are highly expressed in radiation-induced mutant cells. In this study, to elucidate the role of these proteins in the ionizing radiation (toxic chemicals)-induced cell death, we utilized sensed (or antisense, small interference RNA) cells, which overexpress (or down-regulate) RNAs associated with these proteins biosynthesis, and investigated the effects of these genes on the cytotoxicity caused by ionizing radiation, H 2 O 2 and toxic chemicals. We also investigated the functions of downstream target genes of transgelin such as IGF-1Rβ/PI3K/AKT pathway and transgelin/metallothioneine in A-549 and HepG2 cells because such target genes are able to potentiate the cell-killing or cell protecting effects against radiation

Genetic resistance in experimental autoimmune encephalomyelitis. I. Analysis of the mechanism of LeR resistance using radiation chimeras

International Nuclear Information System (INIS)

Pelfrey, C.M.; Waxman, F.J.; Whitacre, C.C.

1989-01-01

Experimental autoimmune encephalomyelitis (EAE) is a cell-mediated autoimmune disease of the central nervous system that has been extensively studied in the rat. The Lewis rat is highly susceptible to the induction of EAE, while the Lewis resistant (LeR) rat is known to be resistant. In this paper, we demonstrate that the LeR rat, which was derived from the Lewis strain by inbreeding of fully resistant animals, is histocompatible with the Lewis strain. Radiation chimeras, a tool for distinguishing between immunologic and nonimmunologic resistance mechanisms, were utilized to analyze the cellular mechanisms involved in genetic resistance to EAE. By transplanting bone marrow cells from LeR rats into irradiated Lewis recipients, Lewis rats were rendered resistant to EAE induction. Likewise, transplanting Lewis bone marrow cells into irradiated LeR recipients rendered LeR rats susceptible. Mixed lymphoid cell chimeras using bone marrow, spleen, and thymus cells in Lewis recipient rats revealed individual lymphoid cell types and cell interactions that significantly affected the incidence and severity of EAE. Our results suggest that LeR resistance is mediated by hematopoietic/immune cells, and that cells located in the spleen appear to play a critical role in the resistance/susceptibility to EAE induction. Depletion of splenic adherent cells did not change the patterns of EAE resistance. In vivo cell mixing studies suggested the presence of a suppressor cell population in the LeR spleen preparations which exerted an inhibitory effect on Lewis autoimmune responses. Thus, the mechanism of LeR resistance appears to be different from that in other EAE-resistant animals

INVESTIGATION OF THERMAL BEHAVIOR OF MULTILAYERED FIRE RESISTANT STRUCTURE

Directory of Open Access Journals (Sweden)

R. GUOBYS

2016-09-01

Full Text Available This paper presents experimental and numerical investigations of thermal behavior under real fire conditions of new generation multilayered fire resistant structure (fire door, dimensions H × W × D: 2090 × 980 × 52 mm combining high strength and fire safety. This fire door consists of two steel sheets (thickness 1.5 and 0.7 mm with stone wool ( = 33 kg/m3, k = 0.037 W/mK, E = 5000 N/m2,  = 0.2 insulating layer in between. One surface of the structure was heated in fire furnace for specified period of time of 60 min. Temperature and deformation of opposite surface were measured from outside at selected measuring points during fire resistance test. Results are presented as temperature-time and thermal deformation-time graphs. Experimental results were compared with numerical temperature field simulation results obtained from SolidWorks®Simulation software. Numerical results were found to be in good agreement with experimental data. The percent differences between door temperatures from simulation and fire resistance test don’t exceed 8%. This shows that thermal behaviour of such multilayered structures can be investigated numerically, thus avoiding costly and time-consuming fire resistance tests. It is established that investigated structure should be installed in a way that places thicker steel sheet closer to the potential heat source than thinner one. It is also obtained that stone wool layer of higher density should be used to improve fire resistance of the structure.

Isolation and characterization of a radiation resistant thermophilic bacterium from radon hot spring

International Nuclear Information System (INIS)

Liang Xinle; Yang Long; Zhang Hong; Zhang Lei

2011-01-01

A radiation resistant and thermophilic bacterium strain R4-33 was isolated from radon hot spring water samples, pretreated with 60 Co γ-rays and UV irradiation. Tests on morphological, physiological and biochemical characters, fatty acid compositions, (G + C) mol% contents, and 16S rDNA sequencing were conducted. The results showed that strain R4-33 was of rod-shape, Gram-negative, atrichous, and endospore-forming. The optimum growth temperature and pH were 60 ℃ and 7.5, respectively. The strain utilized glucose, maltose and trehalose as carbon sources, and hydrolyzed casein and starch. Its catalase positive. The strain was sensitive to penicillin, neomycin, erythromycin, vancomycin, streptomycin, gentamycin, amikacin and ampicillin. The major cellular fatty acids were C 14:1 (48.8%) and C 15:1 (15.2%). The (G + C) mol% content of DNA was 58.2%. Phylogenetic tree based on 16S rDNA sequence showed R4-33 shared highly similarity to those of species in genus Anoxybacillus, especially to that of Anoxybacillus gonensis (99.5%). Based on the above, the strain R4-33 was proposed to the evolution branch of Anoxybacillus and designated as Anoxybacillu sp. R4-33. The UV and γ-radiation tests showed that the strain R4-33 had an ability of resistance to UV of 396 J/m 2 and 60 Co γ-rays irradiation of 14.0 kGy, indicating that the strain was a radiation resistant and thermophilic bacterium. (authors)

Reverse resistance to radiation in KYSE-150R esophageal carcinoma cell after epidermal growth factor receptor signal pathway inhibition by cetuximab

International Nuclear Information System (INIS)

Jing Zhao; Gong Ling; Xie Congying; Zhang Li; Su Huafang; Deng Xia; Wu Shixiu

2009-01-01

Background and purpose: The purpose of our study is to examine the capacity of cetuximab to reverse radiation resistance and investigate molecular mechanisms in human radiation-resistant esophageal carcinoma cell line KYSE-150R. Materials and methods: The radioresistant cell line KYSE-150R was established by using fractionated irradiation (FIR). The KYSE-150R cell line was exposed to radiation, treatment with cetuximab, and combined treatment. Cell cycle distribution and apoptosis were analyzed using flow cytometry. Radiation survival was analyzed using clonogenic assays. RT 2 profiler TM PCR array was performed to analyze EGF/PDGF signaling pathway genes. Results: The established esophageal carcinoma cell line KYSE-150R showed higher radioresistance than parental cell line. Cetuximab could reverse the radiation resistance of KYSE-150R cells. Cell cycle analysis showed that combination with radiation and cetuximab resulted in the accumulation of cells in G1 and G2/M phases, with the reduction of cells within the S phase. Cetuximab enhanced the apoptosis induced by radiation. RT 2 profiler TM array showed that some intracellular signaling genes deriving from EGF/PDGF signaling pathway regulated by cetuximab. Conclusions: Irradiation combined with EGFR blocked by cetuximab may reverse the resistance to radiation in radioresistant esophageal carcinoma cell. The mechanisms may include cell cycle perturbation and enhancement of radiation-induced apoptosis. Further studies are needed to evaluate the role of cetuximab in combination with radiotherapy in the management of esophageal carcinoma.

Some aspects of radiation resistance of wide-gap metal oxides

International Nuclear Information System (INIS)

Lushchik, Aleksandr; Feldbach, Eduard; Galajev, Semjon; Kaerner, Tiit; Liblik, Peeter; Lushchik, Cheslav; Maaroos, Aarne; Nagirnyi, Vitali; Vasil'chenko, Evgeni

2007-01-01

Wide-gap oxides drastically differ in radiation resistance against nonimpact mechanisms of defect creation depending on the ratio between the values of the energy gap E g and the formation energy of a pair of Frenkel defects (FD) E FD . Materials with E g >E FD are radiation-sensitive even at a low excitation density, while the efficiency of FD creation in the materials with E g FD is noticeable only under a high excitation density or in the presence of impurity centers serving as the promoters of radiation damage due to the nonimpact mechanisms. Novel experimental results on the FD creation in the bulk of MgO single crystals (E g FD ) irradiated by swift uranium ions at 300 K and 5 keV electrons at 6 K are presented. The prospects of luminescent protection against radiation damage as well as of the decrease of the luminescence efficiency due to the suppression of nonradiative recombination of electrons and holes (both relaxed and nonrelaxed) by doping the material with a sufficient amount of luminescent impurity ions are considered on the example of spectral transformers for plasma display panels

Effect of solar radiation on multidrug resistant E. coli strains and antibiotic mixture photodegradation in wastewater polluted stream.

Science.gov (United States)

Rizzo, L; Fiorentino, A; Anselmo, A

2012-06-15

The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC>256 μg/mL) and SMZ (MIC>1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t(1/2)=24 min)risk of the development of resistance to SMZ in surface water is significantly higher compared to CPX and AMX. Copyright © 2012 Elsevier B.V. All rights reserved.

X- and gamma-ray N+PP+ silicon detectors with high radiation resistance

International Nuclear Information System (INIS)

Petris, M.; Ruscu, R.; Moraru, R.; Cimpoca, V.

1998-01-01

We have investigated the use of p-type silicon detectors as starting material for X-and gamma-ray detectors because of several potential benefits it would bring: 1. high purity p-type silicon grown by the float-zone process exhibits better radial dopant uniformity than n-type float-zone silicon; 2. it is free of radiation damage due to the neutron transmutation doping process and behaves better in a radiation field because mainly acceptor like centers are created through the exposure and the bulk material type inversion does not occur as in the n-type silicon. But the p-type silicon, in combination with a passivating layer of silicon dioxide, leads to a more complex detector layout since the positive charge in the oxide causes an inversion in the surface layer under the silicon dioxide. Consequently, it would be expected that N + P diodes have a higher leakage current than P + N ones. All these facts have been demonstrated experimentally. These features set stringent requirements for the technology of p-type silicon detectors. Our work presents two new geometries and an improved technology for p-type high resistivity material to obtain low noise radiation detectors. Test structures were characterized before and after the gamma exposure with a cumulative dose in the range 10 4 - 5 x 10 6 rad ( 60 Co). Results indicate that proposed structures and their technology enable the development of reliable N + PP + silicon detectors. For some samples (0.8 - 12 mm 2 ), extremely low reverse currents were obtained and, in combination with a low noise charge preamplifier, the splitting of 241 Am X-ray lines was possible and also the Mn Kα line (5.9 keV) was extracted from the noise with a 1.9 keV FWHM at the room temperature. An experimental model of a nuclear probe based on these diodes was designed for X-ray detection applications. (authors)

Resistance of Feather-Associated Bacteria to Intermediate Levels of Ionizing Radiation near Chernobyl.

Science.gov (United States)

Ruiz-González, Mario Xavier; Czirják, Gábor Árpád; Genevaux, Pierre; Møller, Anders Pape; Mousseau, Timothy Alexander; Heeb, Philipp

2016-03-15

Ionizing radiation has been shown to produce negative effects on organisms, although little is known about its ecological and evolutionary effects. As a study model, we isolated bacteria associated with feathers from barn swallows Hirundo rustica from three study areas around Chernobyl differing in background ionizing radiation levels and one control study site in Denmark. Each bacterial community was exposed to four different γ radiation doses ranging from 0.46 to 3.96 kGy to test whether chronic exposure to radiation had selected for resistant bacterial strains. Experimental radiation duration had an increasingly overall negative effect on the survival of all bacterial communities. After exposure to γ radiation, bacteria isolated from the site with intermediate background radiation levels survived better and produced more colonies than the bacterial communities from other study sites with higher or lower background radiation levels. Long-term effects of radiation in natural populations might be an important selective pressure on traits of bacteria that facilitate survival in certain environments. Our findings indicate the importance of further studies to understand the proximate mechanisms acting to buffer the negative effects of ionizing radiation in natural populations.

Irradiation tests of a small-sized motor with radiation resistance

International Nuclear Information System (INIS)

Nakamichi, M.; Ishitsuka, E.; Shimakawa, S.; Kan, S.

2007-01-01

In the Test Blanket Module (TBM) of the International Thermonuclear Experimental Reactor (ITER), tritium production and release behavior will be studied using neutrons from fusion reactions, as the blanket development for a demonstration (DEMO) reactor. For development of the TBM, in-pile functional tests are planned, including an integrated irradiation experiment of a fusion blanket mock-up for pulsed operation simulating the ITER operation mode, using the Japan Materials Testing Reactor (JMTR) of Japan Atomic Energy Agency (JAEA).Due to be installed in an irradiation rig, a small-sized motor has to be developed for rotating a neutron absorber with a window to realize the simulated pulse operation. Since degradation of materials of the motor may be caused by radiation damage due to neutron and gamma-ray irradiation, it is important to examine the soundness of the motor materials under the neutron and gamma irradiation.In the present study, a small-sized motor with increased radiation resistance was developed as follows. A design of a commercial alternate current (AC) servomotor was adopted in the base structure, and some components of the motor were replaced by those made of radiation-proof materials, through elimination of organic materials. Polyester-coated wire for field coil and epoxy for fixed resin were replaced by polyimide-coated wire and polysiloxane filled with MgO and Al 2 O 3 , respectively. Furthermore, inorganic lubricant (Mo-based coating of 4 micro meter in thickness) was treated on the surface of a gear, instead of organic (polyphenylether) oil.Radiation-induced degradation of the components of the developed small-sized motor was examined using JMTR and the Japan Research Reactor No.4 (JRR-4) of JAEA. The motor was operating normally up to a gamma-ray dose of 7 x 10 8 Gy, a fast neutron (E>1 MeV) fluence of 2 x 10 21 m -2 and a thermal neutron (E 22 m -2 . The irradiated gamma-ray dose for this motor is about 700 times as high as the operation

The effect of morphology and surface composition on radiation resistance of heterogeneous material CdS-PbS

Energy Technology Data Exchange (ETDEWEB)

Malyar, I. V., E-mail: imalyar@yandex.ru; Stetsyura, S. V., E-mail: stetsyurasv@info.sgu.ru [Chernyshevsky Saratov State University (Russian Federation)

2011-07-15

As a result of a complex study of the heterophase photosensitive material CdS-PbS by the methods of scanning electron microscopy and Auger spectrometry, it has been found that the radiation resistance of this material depends on the morphology and phase composition at its surface. It is shown that, as the temperature of annealing is increased, aggregations with predominant content of PbS grow; simultaneously, the composition of these aggregations varies as a consequence of the reaction of substitution of sulfur atoms with oxygen atoms. The latter of the aforementioned processes brings about a decrease in the radiation resistance of the heterophase photosensitive material CdS-PbS, which is accounted for by a decrease in the gettering due to appearance of an intermediate oxidized layer between PbS and CdS. An increase in the sizes and number of spherical aggregations at the surface, which consist of crystallites with predominant content of PbS, brings about an increase in the radiation resistance.

Composite plasma electrolytic oxidation to improve the thermal radiation performance and corrosion resistance on an Al substrate

Energy Technology Data Exchange (ETDEWEB)

Kim, Donghyun [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Sung, Dahye [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of); Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Lee, Junghoon [Department of Mechanical Engineering, Stevens Institute of Technology, Hoboken, NJ 07030 (United States); Kim, Yonghwan [Korea Institute of Industrial Technology (KITECH), Busan 46742 (Korea, Republic of); Chung, Wonsub, E-mail: wschung1@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 46241 (Korea, Republic of)

2015-12-01

Highlights: • Composite plasma electrolytic oxidation was performed using dispersed CuO particles in convectional PEO electrolyte. • Thermal radiation performance and corrosion resistance were examined by FT-IR spectroscopy and electrochemical methods, respectively. • Deposited copper oxide on the surface of the Al substrate was enhanced the corrosion resistance and the emissivity compared with the conventional PEO. - Abstract: A composite plasma electrolytic oxidation (PEO) was performed for enhancing the thermal radiation performance and corrosion resistance on an Al alloy by dispersing cupric oxide (CuO) particles in a conventional PEO electrolyte. Cu-based oxides (CuO and Cu{sub 2}O) formed by composite PEO increased the emissivity of the substrate to 0.892, and made the surface being dark color, similar to a black body, i.e., an ideal radiator. In addition, the corrosion resistance was analyzed using potentio-dynamic polarization and electrochemical impedance spectroscopy tests in 3.5 wt.% NaCl aqueous solution. An optimum condition of 10 ampere per square decimeter (ASD) current density and 30 min processing time produced appropriate surface morphologies and coating thicknesses, as well as dense Cu- and Al-based oxides that constituted the coating layers.

Probability based high temperature engineering creep and structural fire resistance

CERN Document Server

Razdolsky, Leo

2017-01-01

This volume on structural fire resistance is for aerospace, structural, and fire prevention engineers; architects, and educators. It bridges the gap between prescriptive- and performance-based methods and simplifies very complex and comprehensive computer analyses to the point that the structural fire resistance and high temperature creep deformations will have a simple, approximate analytical expression that can be used in structural analysis and design. The book emphasizes methods of the theory of engineering creep (stress-strain diagrams) and mathematical operations quite distinct from those of solid mechanics absent high-temperature creep deformations, in particular the classical theory of elasticity and structural engineering. Dr. Razdolsky’s previous books focused on methods of computing the ultimate structural design load to the different fire scenarios. The current work is devoted to the computing of the estimated ultimate resistance of the structure taking into account the effect of high temperatur...

Labeling for Big Data in radiation oncology: The Radiation Oncology Structures ontology.

Science.gov (United States)

Bibault, Jean-Emmanuel; Zapletal, Eric; Rance, Bastien; Giraud, Philippe; Burgun, Anita

2018-01-01

Leveraging Electronic Health Records (EHR) and Oncology Information Systems (OIS) has great potential to generate hypotheses for cancer treatment, since they directly provide medical data on a large scale. In order to gather a significant amount of patients with a high level of clinical details, multicenter studies are necessary. A challenge in creating high quality Big Data studies involving several treatment centers is the lack of semantic interoperability between data sources. We present the ontology we developed to address this issue. Radiation Oncology anatomical and target volumes were categorized in anatomical and treatment planning classes. International delineation guidelines specific to radiation oncology were used for lymph nodes areas and target volumes. Hierarchical classes were created to generate The Radiation Oncology Structures (ROS) Ontology. The ROS was then applied to the data from our institution. Four hundred and seventeen classes were created with a maximum of 14 children classes (average = 5). The ontology was then converted into a Web Ontology Language (.owl) format and made available online on Bioportal and GitHub under an Apache 2.0 License. We extracted all structures delineated in our department since the opening in 2001. 20,758 structures were exported from our "record-and-verify" system, demonstrating a significant heterogeneity within a single center. All structures were matched to the ROS ontology before integration into our clinical data warehouse (CDW). In this study we describe a new ontology, specific to radiation oncology, that reports all anatomical and treatment planning structures that can be delineated. This ontology will be used to integrate dosimetric data in the Assistance Publique-Hôpitaux de Paris CDW that stores data from 6.5 million patients (as of February 2017).

Carbon glass-ceramics and their radiation resistance

International Nuclear Information System (INIS)

Virgil'ev, Yu. S.

1995-01-01

Structural carbon materials (SCMs) hold great promise for use in numerous plasma-facing components of fusion reactors. One possible candidate for this use is carbon glass-ceramic. Therefore, it is not surprising that there is considerable interest in studying its properties and their variations upon exposure to different radiations, such as neutrons, high-energy electrons, and light ions (H + , D + , and He + ). Here, the authors summarize data accumulated to date on the structure and properties of commercial carbon glass-ceramics and their behavior under irradiation with neutrons, electrons, and some ions

Radiation effects on structural ceramics in fusion

International Nuclear Information System (INIS)

Hopkins, G.R.; Price, R.J.; Trester, P.W.

1986-01-01

Ceramics are required to serve in a conventional role as electrical and thermal insulators and dielectrics in fusion power reactors. In addition, certain ceramic materials can play a unique structural role in fusion power reactors by virtue of their very low induced radioactivity from fusion neutron capture. The aspects of safety, long-term radioactive waste management, and personnel access for maintenance and repair can all be significantly improved by applying the low-activation ceramics to the structural materials of the first-wall and blanket regions of a fusion reactor. Achievement of long service life at high structural loads and thermal stresses on the materials exposed to high-radiation doses presents a critical challenge for fusion. In this paper, we discuss radiation effects on structural ceramics for fusion application

Resistance and Security Index of Networks: Structural Information Perspective of Network Security.

Science.gov (United States)

Li, Angsheng; Hu, Qifu; Liu, Jun; Pan, Yicheng

2016-06-03

Recently, Li and Pan defined the metric of the K-dimensional structure entropy of a structured noisy dataset G to be the information that controls the formation of the K-dimensional structure of G that is evolved by the rules, order and laws of G, excluding the random variations that occur in G. Here, we propose the notion of resistance of networks based on the one- and two-dimensional structural information of graphs. Given a graph G, we define the resistance of G, written , as the greatest overall number of bits required to determine the code of the module that is accessible via random walks with stationary distribution in G, from which the random walks cannot escape. We show that the resistance of networks follows the resistance law of networks, that is, for a network G, the resistance of G is , where and are the one- and two-dimensional structure entropies of G, respectively. Based on the resistance law, we define the security index of a network G to be the normalised resistance of G, that is, . We show that the resistance and security index are both well-defined measures for the security of the networks.

Resistance and Security Index of Networks: Structural Information Perspective of Network Security

Science.gov (United States)

Li, Angsheng; Hu, Qifu; Liu, Jun; Pan, Yicheng

2016-01-01

Recently, Li and Pan defined the metric of the K-dimensional structure entropy of a structured noisy dataset G to be the information that controls the formation of the K-dimensional structure of G that is evolved by the rules, order and laws of G, excluding the random variations that occur in G. Here, we propose the notion of resistance of networks based on the one- and two-dimensional structural information of graphs. Given a graph G, we define the resistance of G, written , as the greatest overall number of bits required to determine the code of the module that is accessible via random walks with stationary distribution in G, from which the random walks cannot escape. We show that the resistance of networks follows the resistance law of networks, that is, for a network G, the resistance of G is , where and are the one- and two-dimensional structure entropies of G, respectively. Based on the resistance law, we define the security index of a network G to be the normalised resistance of G, that is, . We show that the resistance and security index are both well-defined measures for the security of the networks. PMID:27255783

Resistance and Security Index of Networks: Structural Information Perspective of Network Security

Science.gov (United States)

Li, Angsheng; Hu, Qifu; Liu, Jun; Pan, Yicheng

2016-06-01

Recently, Li and Pan defined the metric of the K-dimensional structure entropy of a structured noisy dataset G to be the information that controls the formation of the K-dimensional structure of G that is evolved by the rules, order and laws of G, excluding the random variations that occur in G. Here, we propose the notion of resistance of networks based on the one- and two-dimensional structural information of graphs. Given a graph G, we define the resistance of G, written , as the greatest overall number of bits required to determine the code of the module that is accessible via random walks with stationary distribution in G, from which the random walks cannot escape. We show that the resistance of networks follows the resistance law of networks, that is, for a network G, the resistance of G is , where and are the one- and two-dimensional structure entropies of G, respectively. Based on the resistance law, we define the security index of a network G to be the normalised resistance of G, that is, . We show that the resistance and security index are both well-defined measures for the security of the networks.

Radiation induced crosslinking of polytetrafluoroethylene

International Nuclear Information System (INIS)

Oshima, Akihiro; Tabata, Yoneho; Ikeda, Shigetoshi; Otsuhata, Kazushige; Kudoh, Hisaaki; Seguchi, Tadao.

1995-01-01

The Irradiation temperature effect on polytetrafluoroethylene (PTFE) from room temperature to 380degC was investigated by tensile test and thermal analysis. The behavior of tensile properties and changes of crystallinity on irradiation indicated the formation of a network structure in PTFE by radiation induced crosslinking in inert gas in the molten state just above the melting temperature of PTFE (327degC). The crosslinked PTFE showed a much improved radiation resistance in an atmospheric radiation field. (author)

The effects of low-level ionizing radiation and copper exposure on the incidence of antibiotic resistance in lentic biofilm bacteria.

Science.gov (United States)

McArthur, J Vaun; Dicks, Christian A; Bryan, A Lawrence; Tuckfield, R Cary

2017-09-01

Environmental reservoirs of antibiotic resistant bacteria are poorly understood. Understanding how the environment selects for resistance traits in the absence of antibiotics is critical in developing strategies to mitigate this growing menace. Indirect or co-selection of resistance by environmental pollution has been shown to increase antibiotic resistance. However no attention has been given to the effects of low-level ionizing radiation or the interactions between radiation and heavy metals on the maintenance or selection for antibiotic resistance (AR) traits. Here we explore the effect of radiation and copper on antibiotic resistance. Bacteria were collected from biofilms in two ponds - one impacted by low-level radiocesium and the other an abandoned farm pond. Through laboratory controlled experiments we examined the effects of increasing concentrations of copper on the incidence of antibiotic resistance. Differences were detected in the resistance profiles of the controls from each pond. Low levels (0.01 mM) of copper sulfate increased resistance but 0.5 mM concentrations of copper sulfate depressed the AR response in both ponds. A similar pattern was observed for levels of multiple antibiotic resistance per isolate. The first principal component response of isolate exposure to multiple antibiotics showed significant differences among the six isolate treatment combinations. These differences were clearly visualized through a discriminant function analysis, which showed distinct antibiotic resistance response patterns based on the six treatment groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of electron beam radiation on mechanical properties and on the resistance to punctures caused by Plodia interpunctella in cereal bar packaging

International Nuclear Information System (INIS)

Alves, Juliana N.; Moura, Esperidiana A.B.; Oliveira, Vitor M.; Potenza, Marcos R.; Arthur, Valter

2009-01-01

Plodia interpunctella is an important pest in stored products in the tropical and subtropical regions, infesting grains and flours. The adult of P. interpunctella is a small butterfly with about 15 - 20mm of spread and the female places separately of 100 the 400 eggs in groups on the grains whose hard incubation some days. This insect infesting diverse types of food packaging, depreciating the products and causing economic losses. It is therefore critical for these products a packaging that presents, in addition to good mechanical, barrier and machinability properties, a good resistance to puncture by insects, in order to prevent the contact and spread of pests in the packaged food. This study evaluates the changes on mechanical properties and puncture resistance by P. interpunctella in BOPPmet/BOPP structure, used commercially as cereal bar packaging, after electron beam irradiation. The material samples were irradiated up to 120 kGy using a 1.5 MeV electrostatic accelerator, at room temperature, in air, dose rate 11.22 kGy/s. Irradiation doses were measured using cellulose triacetate film dosimeters 'CTA-FTR-125' from Fuji Photo Film Co. Ltd. After irradiation the BOPPmet/BOPP samples were subjected to tests of puncture resistance by P. interpunctella, tensile tests and penetration resistance. The results showed significant decreases (p<0.05) in the original mechanical properties of the structures according to the radiation doses applied and effective resistance against punctures by P. interpunctella for irradiated and nonirradiated BOPPmet/BOPP samples. These results indicate that non-irradiated and irradiated BOPPmet/BOPP structure presents puncture resistance against P. interpunctella and that electron-beam irradiation, in conditions studied in this work, may turn the structure inappropriate for cereal bar packaging, due to high reduction its mechanical properties after irradiation. (author)

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Directory of Open Access Journals (Sweden)

Marie Ragon

Full Text Available BACKGROUND: The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. METHODOLOGY/PRINCIPAL FINDINGS: To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta and ascomycete fungi (Ascomycota dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. CONCLUSIONS/SIGNIFICANCE: Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in

Sunlight-exposed biofilm microbial communities are naturally resistant to chernobyl ionizing-radiation levels.

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general diversity patterns, despite increased mutation levels at the single

Sunlight-Exposed Biofilm Microbial Communities Are Naturally Resistant to Chernobyl Ionizing-Radiation Levels

Science.gov (United States)

Ragon, Marie; Restoux, Gwendal; Moreira, David; Møller, Anders Pape; López-García, Purificación

2011-01-01

Background The Chernobyl accident represents a long-term experiment on the effects of exposure to ionizing radiation at the ecosystem level. Though studies of these effects on plants and animals are abundant, the study of how Chernobyl radiation levels affect prokaryotic and eukaryotic microbial communities is practically non-existent, except for a few reports on human pathogens or soil microorganisms. Environments enduring extreme desiccation and UV radiation, such as sunlight exposed biofilms could in principle select for organisms highly resistant to ionizing radiation as well. Methodology/Principal Findings To test this hypothesis, we explored the diversity of microorganisms belonging to the three domains of life by cultivation-independent approaches in biofilms developing on concrete walls or pillars in the Chernobyl area exposed to different levels of radiation, and we compared them with a similar biofilm from a non-irradiated site in Northern Ireland. Actinobacteria, Alphaproteobacteria, Bacteroidetes, Acidobacteria and Deinococcales were the most consistently detected bacterial groups, whereas green algae (Chlorophyta) and ascomycete fungi (Ascomycota) dominated within the eukaryotes. Close relatives to the most radio-resistant organisms known, including Rubrobacter species, Deinococcales and melanized ascomycete fungi were always detected. The diversity of bacteria and eukaryotes found in the most highly irradiated samples was comparable to that of less irradiated Chernobyl sites and Northern Ireland. However, the study of mutation frequencies in non-coding ITS regions versus SSU rRNA genes in members of a same actinobacterial operational taxonomic unit (OTU) present in Chernobyl samples and Northern Ireland showed a positive correlation between increased radiation and mutation rates. Conclusions/Significance Our results show that biofilm microbial communities in the most irradiated samples are comparable to non-irradiated samples in terms of general

Radiation-hardened gate-around n-MOSFET structure for radiation-tolerant application-specific integrated circuits

International Nuclear Information System (INIS)

Lee, Min Su; Lee, Hee Chul

2012-01-01

To overcome the total ionizing dose effect on an n-type metal-oxide-semiconductor field-effect transistor (n-MOSFET), we designed a radiation-hardened gate-around n-MOSFET structure and evaluated it through a radiation-exposure experiment. Each test device was fabricated in a commercial 0.35-micron complementary metal-oxide-semiconductor (CMOS) process. The fabricated devices were evaluated under a total dose of 1 Mrad (Si) at a dose rate of 250 krad/h to obtain very high reliability for space electronics. The experimental results showed that the gate-around n-MOSFET structure had very good performance against 1 Mrad (Si) of gamma radiation, while the conventional n-MOSFET experienced a considerable amount of radiation-induced leakage current. Furthermore, a source follower designed with the gate-around transistor worked properly at 1 Mrad (Si) of gamma radiation while a source follower designed with the conventional n-MOSFET lost its functionality.

Collection of radiation resistant characteristics reports for instruments and materials in high dose rate environment

International Nuclear Information System (INIS)

Kusano, Joichi

2008-03-01

This document presents the collected official reports of radiation irradiation study for the candidate materials to be used in high dose rate environment as J-PARC facility. The effect of radiation damage by loss-beam or secondary particle beam of the accelerators influences the performance and the reliability of various instruments. The knowledge on the radiation resistivity of the materials is important to estimate the life of the equipments, the maintenance interval and dose evaluation for the personnel at the maintenance period. The radiation damage consists with mechanical property, electrical property and gas-evolution property. (author)

Application of living radical polymerization to the synthesis of resist polymers for radiation lithography

Energy Technology Data Exchange (ETDEWEB)

Shimizu, Takashi [Nitto Denko Co. LTD., Shimohozumi 1-1-2, Ibaraki, Osaka 567-8680 (Japan); Ichikawa, Tsuneki [Division of Materials Chemistry, Graduate school of Engineering, Hokkaido University, Sapporo 060-8628 (Japan)]. E-mail: ichikawa@eng.hokudai.ac.jp

2005-07-01

Poly(styrene) and poly(methyl acrylate) with benzyl ester of carboxylic acid at the center of the polymer skeletons were synthesized by living radical polymerization for developing a new type of radiation resist with high resistivity to plasma etching and high sensitivity and spatial resolution to ionizing radiations. The initiators were benzyl esters with two functional groups for living radical polymerization on the benzyl and the carboxylic sides. Introduction of benzyl ester to the polymer skeletons changed the polymers from cross-link type to scission type upon {gamma}-irradiation. Irradiation of the polymers resulted in the binary change of the molecular weight, due to dissociative capture of secondary electrons by the benzyl ester, as M{sub n}R{sub 1}COOCH(C{sub 6}H{sub 5})R{sub 2}M{sub n}+e{sup -}->M{sub n}R{sub 1}COO{sup -}+{sup {center_dot}}CH(C{sub 6}H{sub 5})R{sub 2}M{sub n}. The generated polymer fragments were not decomposed by further irradiation, which suggests that the synthesized polymers have high resistivity to plasma etching.

Structure and radiation induced swelling of steels and alloys

International Nuclear Information System (INIS)

Parshin, A.M.

1983-01-01

Regularities of vacancy void formation and radiation induced swelling of austenitic chromium-nickel steels and alloyse ferritic steels as well as titanium α-alloys under radiation by light and heavy ions and neutrons are considered. Possible methods for preparation of alloys with increased resistance to radiation swelling are described. Accounting for investigations into ferritic steels and α-alloys of titanium the basic way of weakening vacancy smelling is development of continuous homogeneous decomposition of solid solution using alloying with vividly expressed incubation period at a certain volumetric dilatation as well as decompositions of the type of ordering, K-state, lamination of solid solutions, etc. Additional alloying of solid solutions is also shown to be necessary for increasing recrystallization temperature of cold-deformed steel

Radiation response of human lung cancer cells with inherent and acquired resistance to cisplatin

International Nuclear Information System (INIS)

Twentyman, P.R.; Wright, K.A.; Rhodes, T.

1991-01-01

We have derived sublines of three human lung cancer cell lines with acquired resistance to cisplatin. The cisplatin resistant sublines of NCI-H69 (small cell), COR-L23 (large cell), and MOR (adenocarcinoma) show 5.3 fold, 3.1 fold, and 3.8 fold resistance, respectively, determined in a 6-day MTT assay. Although the parent lines show a wide range of glutathione content per cell, the sublines each show similar values to their corresponding parent line. Radiation response curves have been obtained using a soft agar clonogenic assay. Values obtained for the parent lines (95% CL in parentheses) were: NCI-H69: Do = 0.99 Gy (0.87-1.16), n = 2.9 (1.6-5.2), GSH = 14 ng/10(4) cells; COR-L23: Do = 1.23 Gy (1.05-1.49), n = 1.3 (0.7-2.2), GSH = 47 ng/10(4) cells; MOR: Do = 1.66 Gy (1.48-1.88), n = 3.0 (1.9-4.8), GSH = 86 ng/10(4) cells. The cisplatin resistant variants of NCI-H69 and COR-L23 showed 31% and 63% increases, respectively, in Do compared to their parent lines, whereas no change in radiation response was seen in MOR. In this panel of lines, therefore, although there is a correlation between glutathione content and radiosensitivity of the parent cell lines, acquired resistance to cisplatin is not accompanied by increased glutathione content. However, two of the three cisplatin resistant lines do show a significantly reduced radiosensitivity

Resistance to ionizing radiations of materials installed at the CERN accelerators

International Nuclear Information System (INIS)

Schoenbacher, H.

1982-01-01

All materials installed in high energy accelerators along the lines of primary and secondary beams are exposed to ionizing radiation. This can in certain cases cause a degradation of the properties of these materials and consequently affect the good function of the installation. The author has taken at CERN large number of samples of materials in order to determine their radioresistance. Generally the organic materials and the electronic components are more sensitive to ionizing radiation. The author presents the results of these studies which concern the isolations of the cables (polyethylene, polyvinyl chloride, caoutchouc ethylene propylene, etc.), the isolations for the magnets on the base of epoxy resins, as well as other thermoresistant and thermoplastic products. The author equally presents a choice of materials and components which are used at CERN and which are resistant to radiations above an integral dose of 10 7 -10 8 Gy. (orig.)

Materials science created by synchrotron radiation

International Nuclear Information System (INIS)

Oshima, Masaharu

2015-01-01

We survey the use of synchrotron radiation for studies on oxides. High luminosity enables the spectroscopy with high energy-resolution in soft X-ray and vacuum ultraviolet region. Element analysis is possible by examining absorption edge in the X-ray absorption spectra. Time-resolved measurements are possible due to the pulsed nature of the radiation. The radiation can bear linear or circular polarization. The feature of molecules adhered on a surface can be clarified by using linearly polarized radiation. The circularly polarized radiation, on the other hand, clarifies the magnetic structure. The structure information so far unknown can be obtained by using space- or time-coherent radiation. We show studies using synchrotron radiation on LSI gate oxide foils, variable resistance RAM, strongly correlated oxide foils, and the oxide as positive electrode of Li ion battery. (J.P.N.)

Structured thermal surface for radiative camouflage.

Science.gov (United States)

Li, Ying; Bai, Xue; Yang, Tianzhi; Luo, Hailu; Qiu, Cheng-Wei

2018-01-18

Thermal camouflage has been successful in the conductive regime, where thermal metamaterials embedded in a conductive system can manipulate heat conduction inside the bulk. Most reported approaches are background-dependent and not applicable to radiative heat emitted from the surface of the system. A coating with engineered emissivity is one option for radiative camouflage, but only when the background has uniform temperature. Here, we propose a strategy for radiative camouflage of external objects on a given background using a structured thermal surface. The device is non-invasive and restores arbitrary background temperature distributions on its top. For many practical candidates of the background material with similar emissivity as the device, the object can thereby be radiatively concealed without a priori knowledge of the host conductivity and temperature. We expect this strategy to meet the demands of anti-detection and thermal radiation manipulation in complex unknown environments and to inspire developments in phononic and photonic thermotronics.

Irradiation of: MOS field effect structures effect of the radiation dose

International Nuclear Information System (INIS)

Leray, J.L.

1989-01-01

The radiation effects on the structure and the operation of a metal-oxide semiconductor (MOS) are studied. The phenomenology of the radiation damage is analyzed as a function of the accumulated radiation dose and the time. The chronology of the phenomena which takes place in the oxide and the radiation transient phases in MOS structures are discussed. The equivalence of different radiations on SiO2 and other semiconductors is analyzed. The models applied to the study of the radiation permanent effects are reviewed [fr

Use of radiation for improving vines regarding their resistance to mildew

International Nuclear Information System (INIS)

Coutinho, M.P.

1977-01-01

Vines (Vitis vinifera) resistant to mildew (Plasmopara viticola) offer real advantages in Europe, and the problems of producing such vines were studied for a long time. At first conventional techniques were used, obtaining plants with high yield and with resistance persisting under widely differing ecological conditions; moreover, pathogenically different biotypes of Plasmopara have never been found. However, various factors - such as the quantitative nature of this resistance, which is controlled by a polygenic system, certain genetic correlations between resistance and poor quality of the grapes and the lack of resistance sources in V. vinifera - suggested that mutagenesis should be included among the methods used for the improvement of vines. Hence shoots and, more particularly, seeds have been undergoing irradiation with X-rays and neutrons since 1966. The exposure of seeds to low radiation doses (about 1000rad), particularly of X-rays, has in most varieties produced a very welcome increase in the germination percentage. Seedlings from irradiated seeds are selected mainly on the basis of the characteristics of the infection spots which develop on the leaves. In V. vinifera, resistance to mildew is reflected not in necroses but in small and usually not very sporulated spots. Using these criteria, the author has already selected - after natural infections and inoculations - plants representing approximately 0.001-0.0025% of the total number of plants screened. Tables illustrate the selection procedure up to 1976

Radiation damage of structural materials

International Nuclear Information System (INIS)

Koutsky, J.; Kocik, J.

1994-01-01

Maintaining the integrity of nuclear power plants (NPP) is critical in the prevention or control of severe accidents. This monograph deals with both basic groups of structural materials used in the design of light-water nuclear reactors, making the primary safety barriers of NPPs. Emphasis is placed on materials used in VVER-type nuclear reactors: Cr-Mo-V and Cr-Ni-Mo-V steel for reactor pressure vessels (RPV) and Zr-Nb alloys for fuel element cladding. The book is divided into seven main chapters, with the exception of the opening one and the chapter providing phenomenological background for the subject of radiation damage. Chapters 3-6 are devoted to RPV steels and chapters 7-9 to zirconium alloys, analyzing their radiation damage structure, changes of mechanical properties due to neutron irradiation as well as factors influencing the degree of their performance degradation. The recovery of damaged materials is also discussed. Considerable attention is paid to a comparison of VVER-type and western-type light-water materials

Fracture resistance enhancement of layered structures by multiple cracks

DEFF Research Database (Denmark)

Goutianos, Stergios; Sørensen, Bent F.

2016-01-01

A theoretical model is developed to test if the fracture resistance of a layered structure can be increased by introducing weak layers changing the cracking mechanism. An analytical model, based on the J integral, predicts a linear dependency between the number of cracks and the steady state...... fracture resistance. A finite element cohesive zone model, containing two cracking planes for simplicity, is used to check the theoretical model and its predictions. It is shown that for a wide range of cohesive law parameters, the numerical predictions agree well quantitatively with the theoretical model....... Thus, it is possible to enhance considerably the fracture resistance of a structure by adding weak layers....

On possibility to make a new type of calorimeter: radiation resistant and fast

International Nuclear Information System (INIS)

Derevshchikov, A.A.; Khodyrev, V.Yu.; Kryshkin, V.I.; Rakhmatov, V.E.; Ronzhin, A.I.

1990-01-01

It is proposed to use electron multipliers, which directly detect low energy shower particles as an active element in sandwich calorimeters. The approach pffers fast and radiation resistant calorimetry. Test of the method is presented with the use of a microchannel plate. 4 refs.; 4 figs

Irradiation behavior of developed radiation resistance optical-fibers and observed optical radiation from their SiO2 cores under reactor irradiation

International Nuclear Information System (INIS)

Shikama, Tatsuo; Narui, Minoru; Kayano, Hideo; Kakuta, Tsunemi; Sagawa, Tsutomu; Sanada, Kazuo; Shamoto, Naoki; Uramoto, Toshimasa.

1994-01-01

Two kinds of optical fibers were irradiated in a fission reactor, JMTR(Japan Materials Testing Reactor), up to a 1.55x10 19 n/cm 2 fast neutron fluence and a 3.3x10 9 Gy ionizing dose at 370K. Optical transmission spectra were measured in the wavelength range of 450-1750nm, in-situ. Growth of strong optical absorption bands were observed in the range of wavelength shorter than 750nm. In the meantime, the fibers showed good radiation-resistance in the range of wavelength longer than 750nm. Optical radiations were observed from SiO 2 optical fibers under irradiation. A major part of the observed optical radiations is thought to be composed of broad optical radiation in the whole wavelength range studied in the present experiment. This broad optical radiation will be generated by the process of so-called Cerenkov radiation. Also, a sharp optical radiation peak was found at 1270nm on a F-doped fiber. This peak is thought to relate with doped Fluorine ions and ionizing gamma-ray irradiation. (author)

Effects of gamma ray irradiation on the radiation resistance, dielectric and mechanical properties of polyvinylchloride containing plasticizer and stabilizer

International Nuclear Information System (INIS)

Kim, B.H.; Lee, J.I.; Kang, D.Y.

1977-01-01

To investigate the properties of radiation resistance together with dielectric and mechanical relaxation behaviors of polyvinylchloride exposed to several different doses under the gamma ray of cobalt-60 source, experiments were carried out using the specimens prepared by mixing dibutyl-tin-dilaurate and dibutyl-tin-dimaleate as stabilizers with or without adding dioctylphthalate as a plasticizer. The origin of the absorption band at 1540-1640 cm -1 on infrared spectrum seemed to be RCOO - ion obtained from the ionization of the stabilizer, and this peak could be useful as a measure of radiation resistance on polyvinylchloride. Addition of increasing plasticizer to polyvinylchloride exhibited increasing radiation resistance and the reason for the result might be attributable to aromatic resonance adsorption of radiation energy by the dioctylphthalate. On dose dependent dielectric characteristics, nonplastized specimen showed peak at about 10 Mrad and that the peak disappeared on the plastification of specimens. Such phenomena might be explainable in considering the statistical distribution of scissored chain molecular segments as well as the plastification process of the plasticizer to polyvinylchloride chain molecules. (author)

Computational methods for structural load and resistance modeling

Science.gov (United States)

Thacker, B. H.; Millwater, H. R.; Harren, S. V.

1991-01-01

An automated capability for computing structural reliability considering uncertainties in both load and resistance variables is presented. The computations are carried out using an automated Advanced Mean Value iteration algorithm (AMV +) with performance functions involving load and resistance variables obtained by both explicit and implicit methods. A complete description of the procedures used is given as well as several illustrative examples, verified by Monte Carlo Analysis. In particular, the computational methods described in the paper are shown to be quite accurate and efficient for a material nonlinear structure considering material damage as a function of several primitive random variables. The results show clearly the effectiveness of the algorithms for computing the reliability of large-scale structural systems with a maximum number of resolutions.

Radiation Resistance of the U(Al, Si)3 Alloy: Ion-Induced Disordering

Science.gov (United States)

Yaniv, Gili; Horak, Pavel; Vacik, Jiri; Mykytenko, Natalia; Rafailov, Gennady; Dahan, Itzchak; Fuks, David; Kiv, Arik

2018-01-01

During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current research, U(Al, Si)3 composition was studied as a potential constituent of an interaction layer. Phase content of the alloy of an interest was ordered U(Al, Si)3, structure of which was reported earlier, and pure Al (constituting less than 20 vol % of the alloy). This alloy was investigated prior and after the irradiation performed by Ar ions at 30 keV. The irradiation was performed on the transmission electron microscopy (TEM, JEOL, Japan) samples, characterized before and after the irradiation process. Irradiation induced disorder accompanied by stress relief. Furthermore, it was found that there is a dose threshold for disordering of the crystalline matter in the irradiated region. Irradiation at doses equal or higher than this threshold resulted in almost solely disordered phase. Using the program “Stopping and Range of Ions in Matter” (SRIM), the parameters of penetration of Ar ions into the irradiated samples were estimated. Based on these estimations, the dose threshold for ion-induced disordering of the studied material was assessed. PMID:29393870

Effect of neutron radiation on mechanical properties of permanent near core structures

International Nuclear Information System (INIS)

Tavassoli, A.A.

1988-01-01

Several hundred specimens have been tested in order to assess the effects of low dose neutron radiation ( 0 C and ductility and toughness are primary design concerns, the changes provoked, by doses up to 1.3 dpa, in overall mechanical properties of welded joints are small. For upper core structure, where the operating temperature is about 550 0 C and fatigue and creep resistance are major design needs, the changes induced, through formation of up to about 2 appm helium, in conventional fatigue properties or fatigue with short hold times are negligible. With increasing hold time, intergranular rupture in irradiated specimens is enhanced but the limited number of tests does not allow definite conclusions to be drawn. 53 refs, 3 tabs, 9 figs

Patterning characteristics of a chemically-amplified negative resist in synchrotron radiation lithography

International Nuclear Information System (INIS)

Deguchi, Kimiyoshi; Miyoshi, Kazunori; Ishii, Tetsuyoshi; Matsuda, Tadahito

1992-01-01

To explore the applicability of synchrotron radiation X-ray lithography for fabricating sub-quartermicron devices, we investigate the patterning characteristics of the chemically-amplified negative resist SAL601-ER7. Since these characteristics depend strongly on the conditions of the chemical amplification process, the effects of post-exposure baking and developing conditions on sensitivity and resolution are examined. The resolution-limiting factors are investigated, revealing that pattern collapse during the development process and fog caused by Fresnel diffraction, photo-electron scattering, and acid diffusion in the resist determine the resolution and the maximum aspect ratio of the lines and spaces pattern. Using the model of a swaying beam supported at one end, it is shown that pattern collapse depends on the resist pattern's flexural stiffness. Patterning stability, which depends on the delay time between exposure and baking, is also discussed. (author)

The radiation resistance of thermoset plastics: Pt. 1

International Nuclear Information System (INIS)

Gilfrich, H.-P.; Roesinger, S.; Wilski, H.

1991-01-01

Not much is known about the influence of ionising radiation on thermoset plastics. In particular the influence of the dose rate on the radiation resistance has not yet been investigated. To get more information about this subject we have irradiated a number of thermoset plastics of different chemical compositions in two ways: irradiation with electrons at a high dose rate and under exclusion of oxygen and irradiation at an extremely low dose rate in air with the γ-rays of a cobalt-60 source. The latter experiment lasting over a period of 10 years (and in some cases even 16 years). In this first part of our report we describe the experimental conditions as well as the results obtained using two phenolic plastics with different inorganic fillers. In no case did we find any improvement in the properties tested. The mechanical properties deteriorated at high doses, the effects being particularly noticeable in long term experiments. Both materials became more sensitive to the influence of heat and humidity. A relatively reliable extrapolation of the results to a working period of 50 years seems to be possible. (author)

The radiation chemistry of polymer composites

International Nuclear Information System (INIS)

Dole, M.

1991-01-01

With the use of plastics in the construction of space satellites which may be exposed in geosynchronous orbit to 100 MGy (10,000 Mrad) of high-energy radiation in 30 years of use, the effect of these radiations on the polymer becomes of practical importance. To understand the effects we consider first various radiation-resistant groups that are incorporated into the polymer and their relative effectiveness in reducing molecular scissions due to the radiation. The location of such groups in the polymer is also discussed. Next the chemical structures of a number of resins such as epoxies, polyimides, etc. are described followed by a detailed account of methods of improving the radiation resistance of plastics by the incorporation of carbon or glass fibers. Finally, the role of oxygen in causing chain scissions and other effects during irradiation which reduce the mechanical strength of the plastics and the fiber resin composites are also considered. (author)

Radiation enhanced copper clustering processes in Fe-Cu alloys during electron and ion irradiations as measured by electrical resistivity

International Nuclear Information System (INIS)

Ishino, S.; Chimi, Y.; Bagiyono; Tobita, T.; Ishikawa, N.; Suzuki, M.; Iwase, A.

2003-01-01

To study the mechanism of radiation-enhanced clustering of copper atoms in Fe-Cu alloys, in situ electrical resistivity measurements are performed during irradiation with 100 MeV carbon ions and with 2 MeV electrons at 300 K. Two kinds of highly pure Fe-Cu alloys with Cu content of 0.02 and 0.6 wt% are used. The results are summarized as follows: - Although there is a steep initial resistivity increase below about 10 μdpa, the resistivity steadily decreases after this initial transient in Fe-0.6wt%Cu alloy, while in Fe-0.02wt%Cu alloy, the resistivity either decreases slowly or stays almost constant. The rate of change in resistivity depends on copper concentration. - The rate of change in resistivity per dpa is larger for electron irradiation than for ion irradiation. - Change in dose rate from 10 -8 to 10 -9 dpa/s slightly enhances the rate of resistivity change per dpa. The decrease in resistivity with dose is considered to be due to clustering or precipitation of copper atoms. The initial abrupt increase in resistivity is too large to be accounted for by initial introduction of point defects before copper clustering. Tentatively the phenomenon is explained as due to the formation of embryos of copper precipitates with a large strain field around them. Quantitative evaluation of the results using resistivity contribution of a unit concentration of Frenkel pairs and that of copper atoms gives an important conclusion that more than one copper atom are removed from solid solution by one Frenkel pair. The clustering efficiency is surprisingly high in the present case compared with the ordinary radiation-induced or radiation-enhanced precipitation processes

Evaluation of resistance of diamond-like carbon coating to the corpuscular radiation in outer space conditions

Science.gov (United States)

Tomilova, Elizaveta; Bashkov, Valeriy; Mikhalev, Pavel; Fedorchenko, Alexander; Volkova, Yana

2015-02-01

The purpose of this work was to research the resistance of thin coatings to the effects of corpuscular radiation, as well as evaluation speed etching of diamond-like films with different content of diamond phase. There were two samples of monocrystalline silicon with DLC coating. To evaluate the resistance, two groups of grooves were etched on each sample. The depth was then measured to calculate a relative etching ratio of DLC coating. The resistance was determined to be four times that of silicon.

Component nuclear containment structure

International Nuclear Information System (INIS)

Harstead, G.A.

1979-01-01

The invention described is intended for use primarily as a nuclear containment structure. Such structures are required to surround the nuclear steam supply system and to contain the effects of breaks in the nuclear steam supply system, or i.e. loss of coolant accidents. Nuclear containment structures are required to withstand internal pressure and temperatures which result from loss of coolant accidents, and to provide for radiation shielding during operation and during the loss of coolant accident, as well as to resist all other applied loads, such as earthquakes. The nuclear containment structure described herein is a composite nuclear containment structure, and is one which structurally combines two previous systems; namely, a steel vessel, and a lined concrete structure. The steel vessel provides strength to resist internal pressure and accommodate temperature increases, the lined concrete structure provides resistance to internal pressure by having a liner which will prevent leakage, and which is in contact with the concrete structure which provides the strength to resist the pressure

A bioinspired study on the compressive resistance of helicoidal fibre structures.

Science.gov (United States)

Tan, Ting; Ribbans, Brian

2017-10-01

Helicoidal fibre structures are widely observed in natural materials. In this paper, an integrated experimental and analytical approach was used to investigate the compressive resistance of helicoidal fibre structures. First, helicoidal fibre-reinforced composites were created using three-dimensionally printed helicoids and polymeric matrices, including plain, ring-reinforced and helix-reinforced helicoids. Then, load-displacement curves under monotonic compression tests were collected to measure the compressive strengths of helicoidal fibre composites. Fractographic characterization was performed using an X-ray microtomographer and scanning electron microscope, through which crack propagations in helicoidal structures were illustrated. Finally, mathematical modelling was performed to reveal the essential fibre architectures in the compressive resistance of helicoidal fibre structures. This work reveals that fibre-matrix ratios, helix pitch angles and interlayer rotary angles are critical to the compressive resistance of helicoidal structures.

LIFE Materials: Topical Assessment Report for LIFE Volume 1 TOPIC: Solid First Wall and Structural Components TASK: Radiation Effects on First Wall

Energy Technology Data Exchange (ETDEWEB)

Caro, A

2008-11-26

This report consists of the following chapters: CHAPTER A: LIFE Requirements for Materials. Part 1: The structure of the First Wall--Basic requirements; A qualitative view of the challenge; The candidate materials; and Base-line material's properties. CHAPTER B: Summary of Existing Knowledge--Brief historical introduction; Design window; The temperature window; Evolution of the design window with damage; Damage calculations; He and H production; Swelling resistance; Incubation dose for swelling; Design criterion No. 1, Strength; Design criterion No. 2, Corrosion resistance; Design criterion No. 3, Creep resistance; Design criterion No. 4, Radiation induced embrittlement; and Conclusions. CHAPTER C: Identification of Gaps in Knowledge & Vulnerabilities. CHAPTER D: Strategy and Future Work.

Microbial cells can cooperate to resist high-level chronic ionizing radiation

OpenAIRE

Shuryak, Igor; Matrosova, Vera Y.; Gaidamakova, Elena K.; Tkavc, Rok; Grichenko, Olga; Klimenkova, Polina; Volpe, Robert P.; Daly, Michael J.

2017-01-01

Understanding chronic ionizing radiation (CIR) effects is of utmost importance to protecting human health and the environment. Diverse bacteria and fungi inhabiting extremely radioactive waste and disaster sites (e.g. Hanford, Chernobyl, Fukushima) represent new targets of CIR research. We show that many microorganisms can grow under intense gamma-CIR dose rates of 13–126 Gy/h, with fungi identified as a particularly CIR-resistant group of eukaryotes: among 145 phylogenetically diverse strain...

Radiation damage to DNA: The importance of track structure

International Nuclear Information System (INIS)

Hill, M.A.

1999-01-01

A wide variety of biological effects are induced by ionizing radiation, from cell death to mutations and carcinogenesis. The biological effectiveness is found to vary not only with the absorbed dose but also with the type of radiation and its energy, i.e., with the nature of radiation tracks. An overview is presented of some of the biological experiments using different qualities of radiation, which when compared with Monte Carlo track structure studies, have highlighted the importance of the localized spatial properties of stochastic energy deposition on the nanometer scale at or near DNA. The track structure leads to clustering of damage which may include DNA breaks, base damage etc., the complexity of the cluster and therefore its biological repairability varying with radiation type. The ability of individual tracks to produce clustered damage, and the subsequent biological response are important in the assessment of the risk associated with low-level human exposure. Recent experiments have also shown that biological response to radiation is not always restricted to the 'hit' cell but can sometimes be induced in 'un-hit' cells near by

Development of high radiation-resistant glass fiber reinforced plastics with cyanate-based resin for superconducting magnet systems

Energy Technology Data Exchange (ETDEWEB)

Idesaki, Akira, E-mail: idesaki.akira@qst.go.jp [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Nakamoto, Tatsushi [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Yoshida, Makoto [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Shimada, Akihiko [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Watanuki 1233, Takasaki, Gunma 370-1292 (Japan); Iio, Masami; Sasaki, Kenichi; Sugano, Michinaka [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Makida, Yasuhiro [Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Ogitsu, Toru [Cryogenic Science Center, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2016-11-15

Highlights: • GFRPs for superconducting magnet systems were developed. • Cyanate-based resins were used for GFRPs as matrices. • Radiation resistance was evaluated based on gas evolution and mechanical properties. • GFRP with bismaleimide-triazine resin exhibited excellent radiation resistance. - Abstract: Glass fiber reinforced plastics (GFRPs) with cyanate ester resin/epoxy resin, bismaleimide resin/epoxy resin, and bismaleimide-triazine resin as matrices were developed for the superconducting magnet systems used in high intensity accelerators. The radiation resistance of these GFRPs was evaluated based on their gas evolution and changes in their mechanical properties after gamma-ray irradiation with dose of 100 MGy in vacuum at ambient temperature. After irradiation, a small amount of gas was evolved from all of the GFRPs, and a slight decrease in mechanical properties was observed compared with the conventional epoxy resin-GFRP, G10. Among the GFRPs, the smallest amount of gas (6 × 10{sup −5} mol/g) was evolved from the GFRP with the bismaleimide-triazine resin, which also retained more than 88% of its flexural strength after 100 MGy irradiation; this GFRP is thus considered the most promising material for superconducting magnet systems.

Protein function prediction involved on radio-resistant bacteria

International Nuclear Information System (INIS)

Mezhoud, Karim; Mankai, Houda; Sghaier, Haitham; Barkallah, Insaf

2009-01-01

Previously, we identified 58 proteins under positive selection in ionizing-radiation-resistant bacteria (IRRB) but absent in all ionizing-radiation-sensitive bacteria (IRSB). These are good reasons to believe these 58 proteins with their interactions with other proteins (interactomes) are a part of the answer to the question as to how IRRB resist to radiation, because our knowledge of interactomes of positively selected orphan proteins in IRRB might allow us to define cellular pathways important to ionizing-radiation resistance. Using the Database of Interacting Proteins and the PSIbase, we have predicted interactions of orthologs of the 58 proteins under positive selection in IRRB but absent in all IRSB. We used integrate experimental data sets with molecular interaction networks and protein structure prediction from databases. Among these, 18 proteins with their interactomes were identified in Deinococcus radiodurans R1. DNA checkpoint and repair, kinases pathways, energetic and nucleotide metabolisms were the important biological process that found. We predicted the interactomes of 58 proteins under positive selection in IRRB. It is hoped our data will provide new clues as to the cellular pathways that are important for ionizing-radiation resistance. We have identified news proteins involved on DNA management which were not previously mentioned. It is an important input in addition to protein that studied. It does still work to deepen our study on these new proteins

Study of multidrug resistance and radioresistance

International Nuclear Information System (INIS)

Kang, Yoon Koo; Yoo, Young Do

1999-04-01

We investigated the mechanism of 5-FU, adriamycin, radiation resistance in Korean gastric cancer cells. First we investigated the relation between Rb and multidrug resistance. Rb stable transfectants exhibited 5- to 10- fold more resistance to adriamycin than the control cells. These Rb transfectants showed increased MDR1 expression. We also investigated up-regulation in radiation-resistant tumor tissues. HSP27, MRP-8, GST, and NKEF-B were up-regulated in radiation resistant tumor. Expression of NKEF-B was also increased by radiation exposure in Head and Neck cells. These results demonstrated that NKEF-B is a stress response protein and it may have an important role in radiation resistance

Radiation damage to DNA: The importance of track structure

CERN Document Server

Hill, M A

1999-01-01

A wide variety of biological effects are induced by ionizing radiation, from cell death to mutations and carcinogenesis. The biological effectiveness is found to vary not only with the absorbed dose but also with the type of radiation and its energy, i.e., with the nature of radiation tracks. An overview is presented of some of the biological experiments using different qualities of radiation, which when compared with Monte Carlo track structure studies, have highlighted the importance of the localized spatial properties of stochastic energy deposition on the nanometer scale at or near DNA. The track structure leads to clustering of damage which may include DNA breaks, base damage etc., the complexity of the cluster and therefore its biological repairability varying with radiation type. The ability of individual tracks to produce clustered damage, and the subsequent biological response are important in the assessment of the risk associated with low-level human exposure. Recent experiments have also shown that...

Identifying the Proteins that Mediate the Ionizing Radiation Resistance of Deinococcus Radiodurans R1

Energy Technology Data Exchange (ETDEWEB)

Battista, John R

2010-02-22

The primary objectives of this proposal was to define the subset of proteins required for the ionizing radiation (IR) resistance of Deinococcus radiodurans R1, characterize the activities of those proteins, and apply what was learned to problems of interest to the Department of Energy.

RAD18 mediates resistance to ionizing radiation in human glioma cells

International Nuclear Information System (INIS)

Xie, Chen; Wang, Hongwei; Cheng, Hongbin; Li, Jianhua; Wang, Zhi; Yue, Wu

2014-01-01

Highlights: • RAD18 is an important mediator of the IR-induced resistance in glioma cell lines. • RAD18 overexpression confers resistance to IR-mediated apoptosis. • The elevated expression of RAD18 is associated with recurrent GBM who underwent IR therapy. - Abstract: Radioresistance remains a major challenge in the treatment of glioblastoma multiforme (GBM). RAD18 a central regulator of translesion DNA synthesis (TLS), has been shown to play an important role in regulating genomic stability and DNA damage response. In the present study, we investigate the relationship between RAD18 and resistance to ionizing radiation (IR) and examined the expression levels of RAD18 in primary and recurrent GBM specimens. Our results showed that RAD18 is an important mediator of the IR-induced resistance in GBM. The expression level of RAD18 in glioma cells correlates with their resistance to IR. Ectopic expression of RAD18 in RAD18-low A172 glioma cells confers significant resistance to IR treatment. Conversely, depletion of endogenous RAD18 in RAD18-high glioma cells sensitized these cells to IR treatment. Moreover, RAD18 overexpression confers resistance to IR-mediated apoptosis in RAD18-low A172 glioma cells, whereas cells deficient in RAD18 exhibit increased apoptosis induced by IR. Furthermore, knockdown of RAD18 in RAD18-high glioma cells disrupts HR-mediated repair, resulting in increased accumulation of DSB. In addition, clinical data indicated that RAD18 was significantly higher in recurrent GBM samples that were exposed to IR compared with the corresponding primary GBM samples. Collectively, our findings reveal that RAD18 may serve as a key mediator of the IR response and may function as a potential target for circumventing IR resistance in human GBM

Structure-borne sound structural vibrations and sound radiation at audio frequencies

CERN Document Server

Cremer, L; Petersson, Björn AT

2005-01-01

Structure-Borne Sound"" is a thorough introduction to structural vibrations with emphasis on audio frequencies and the associated radiation of sound. The book presents in-depth discussions of fundamental principles and basic problems, in order to enable the reader to understand and solve his own problems. It includes chapters dealing with measurement and generation of vibrations and sound, various types of structural wave motion, structural damping and its effects, impedances and vibration responses of the important types of structures, as well as with attenuation of vibrations, and sound radi

Improvement of radiation resistance of polypropylene by blending with polyethylene and polystyrene

International Nuclear Information System (INIS)

Al Aji, Z.

2001-01-01

The use of polypropylene in production of medical component and packaging materials makes it an interesting material for applied research. Since the use of ethylene oxide for sterilization of medical components will be forbidden in the next future because of its carcinogens effect. Therefore, another alternative sterilization methods are required. The use of Gamma radiation is already established for sterilization of some medical components, this technique causes change in the physical mechanical properties of polypropylene, which makes the addition of stabilizers necessary. In this work, blends of domestically used polymers, polypropylene, linear low-density polyethylene, and polystyrene/butadiene were prepared in order to improve the radiation resistance of polypropylene; naphthalene was also used as an additive

Some resistance mechanisms to ultraviolet radiation; Algunos mecanismos de resistencia a radiacion ultravioleta

Energy Technology Data Exchange (ETDEWEB)

Alcantara D, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

2002-12-15

The cyclical exposure of bacterial cells to the ultraviolet light (UV) it has as consequence an increment in the resistance to the lethal effects of this type of radiation, increment that happens as a result of a selection process of favorable genetic mutations induced by the same UV light. With object to study the reproducibility of the genetic changes and the associate mechanisms to the resistance to UV in the bacteria Escherichia coli, was irradiated cyclically with UV light five different derived cultures of a single clone, being obtained five stumps with different resistance grades. The genetic mapping Hfr revealed that so much the mutation events like of selection that took place during the adaptation to the UV irradiation, happened of random manner, that is to say, each one of the resistant stumps it is the result of the unspecified selection of mutations arisen at random in different genes related with the repair and duplication of the DNA. (Author)

Theoretical optimization of base doping concentration for radiation resistance of InGaP subcells of InGaP/GaAs/Ge based on minority-carrier lifetime

International Nuclear Information System (INIS)

Elfiky, Dalia; Yamaguchi, Masafumi; Sasaki, Takuo

2010-01-01

One of the fundamental objectives for research and development of space solar cells is to improve their radiation resistance. InGaP solar cells with low base carrier concentrations under low-energy proton irradiations have shown high radiation resistances. In this study, an analytical model for low-energy proton radiation damage to InGaP subcells based on a fundamental approach for radiative and nonradiative recombinations has been proposed. The radiation resistance of InGaP subcells as a function of base carrier concentration has been analyzed by using the radiative recombination lifetime and damage coefficient K for the minority-carrier lifetime of InGaP. Numerical analysis shows that an InGaP solar cell with a lower base carrier concentration is more radiation-resistant. Satisfactory agreements between analytical and experimental results have been obtained, and these results show the validity of the analytical procedure. The damage coefficients for minority-carrier diffusion length and carrier removal rate with low-energy proton irradiations have been observed to be dependent on carrier concentration through this study. As physical mechanisms behind the difference observed between the radiation-resistant properties of various base doping concentrations, two mechanisms, namely, the effect of a depletion layer as a carrier collection layer and generation of the impurity-related complex defects due to low-energy protons stopping within the active region, have been proposed. (author)

Recent progress and tests of radiation resistant impregnation materials for Nb3Sn coils

International Nuclear Information System (INIS)

Bossert, R.; Krave, S.; Ambrosio, G.; Andreev, N.; Chlachidze, G.; Nobrega, A.; Novitski, I.; Yu, M.; Zlobin, A. V.

2014-01-01

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb 3 Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of “ten stacks” of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy

Recent progress and tests of radiation resistant impregnation materials for Nb3Sn coils

Science.gov (United States)

Bossert, R.; Krave, S.; Ambrosio, G.; Andreev, N.; Chlachidze, G.; Nobrega, A.; Novitski, I.; Yu, M.; Zlobin, A. V.

2014-01-01

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of "ten stacks" of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy.

Clinical and histological study of radiation-resistant cancer of the larynx

Energy Technology Data Exchange (ETDEWEB)

Maeda, K [Osaka Univ. (Japan). Faculty of Medicine

1979-02-01

In its early stage, cancer of the larynx is treated mainly by irradiation. A clinical and histological study of the radiation-resistant cancer of the larynx is reported. From 1958 to 1976, 1190 patients with squamous cell carcinoma of the larynx were treated at the Department of Otolaryngology, Osaka University Hospital. Among them, 597 patients (50.2%) were treated by radiation therapy. In 180 patients who had developed local recurrence after initial irradiation, partial or total laryngectomies were performed and 5-year crude survival rates were 71.3%. Gross examination of the specimens and histological studies were performed on these cases, as well as microangiography. The majority of recurrent glottic cancers were located at the anterior commissure and had some subglottic extention. In the supraglottic cancers, marked invasion to the pre-epiglottic space, perichondritis, and edema of the arytenoids were observed. These findings suggested that the unsuccessful radiation therapy was due to the diagnostic failure of the tumor extention. Fixation of the affected vocal cords and ulcer formation were also observed. Histologically, cancer cells invaded deeply the surrounding tissues as scattered cancer nests with marked hypoxic stromal reaction. This study suggests that radiation therapy should be the initial but non-repetitive treatment of choice for earlystage laryngeal cancers.

Effects of radiation on MOS structures and silicon devices

International Nuclear Information System (INIS)

Braeunig, D.; Fahrner, W.

1983-02-01

A comprehensive view of radiation effects on MOS structures and silicon devices is given. In the introduction, the interaction of radiation with semiconductor material is presented. In the next section, the electrical degradation of semiconductor devices due to this interaction is discussed. The commonly used hardening techniques are shown. The last section deals with testing of radiation hardness of devices. (orig.) [de

Radiation defect formation in two-barrier structures based on silicon

International Nuclear Information System (INIS)

Madatov, R.S.; Abbasov, F.P.; Mustafayev, Yu.M.

2013-01-01

It was developed a silicon-based photodetector with high integral sensitivity in low-wave spectrum. It was investigated the effect of gamma radiation on the mechanism of current transport in the structure of Schottky barrier type and in transitions. It is shown that the double-barrier structures can improve the photovoltaic parameters of conventional detectors. For the first time it was obtained and studied the characteristics of two-barrier structures created on the same plane. The advantages over conventional structures are shown. The annealing point is changing the structure of radiation defects and leads to their disappearance

Simulation of Radiation Heat Transfer in a VAR Furnace Using an Electrical Resistance Network

Science.gov (United States)

Ballantyne, A. Stewart

The use of electrical resistance networks to simulate heat transfer is a well known analytical technique that greatly simplifies the solution of radiation heat transfer problems. In a VAR furnace, radiative heat transfer occurs between the ingot, electrode, and crucible wall; and the arc when the latter is present during melting. To explore the relative heat exchange between these elements, a resistive network model was developed to simulate the heat exchange between the electrode, ingot, and crucible with and without the presence of an arc. This model was then combined with an ingot model to simulate the VAR process and permit a comparison between calculated and observed results during steady state melting. Results from simulations of a variety of alloys of different sizes have demonstrated the validity of the model. Subsequent simulations demonstrate the application of the model to the optimization of both steady state and hot top melt practices, and raises questions concerning heat flux assumptions at the ingot top surface.

Directional radiation pattern in structural-acoustic coupled system

Science.gov (United States)

Seo, Hee-Seon; Kim, Yang-Hann

2005-07-01

In this paper we demonstrate the possibility of designing a radiator using structural-acoustic interaction by predicting the pressure distribution and radiation pattern of a structural-acoustic coupling system that is composed by a wall and two spaces. If a wall separates spaces, then the wall's role in transporting the acoustic characteristics of the spaces is important. The spaces can be categorized as bounded finite space and unbounded infinite space. The wall considered in this study composes two plates and an opening, and the wall separates one space that is highly reverberant and the other that is unbounded without any reflection. This rather hypothetical circumstance is selected to study the general coupling problem between the finite and infinite acoustic domains. We developed an equation that predicts the energy distribution and energy flow in the two spaces separated by a wall, and its computational examples are presented. Three typical radiation patterns that include steered, focused, and omnidirected are presented. A designed radiation pattern is also presented by using the optimal design algorithm.

Gamma radiation shielding materials improved with burning resistance

International Nuclear Information System (INIS)

Nakamura, Michio; Nakamura, Ken-ichi; Yukawa, Katsunori.

1985-01-01

Purpose: To obtain gamma irradiation shielding materials excellent in workability and resistant to burning by using a two component type room temperature vulcanizing silicon rubber composition as the base material. Method: Silicon rubber comprising a diorganopolysiloxane polymer, an alkyl silicate as a crosslinker and a suitable sulfurdizing catalyst, for example, a carboxylate is mixed with iron powder and silicon oxide powder as reinforcing and flame retardant material and applied with molding. The iron powder and the silica rocks powder have grain size of 50 - 150 μm and 1 - 70 μm and charged by the amount of from 55 to 60 % by weight and from 20 to 25 % by weight respectively. The fluidizing property is impaired if the particle size of the silica rocks powder is less than 1 μm and, while on the other hand, no desired specific gravity of a predetermined value can be obtained for the molding product if the filled amount of the iron powder is less than 55 %. The oxygen index of the molding product is 45 to improve the burning resistance. The materials are excellent in the air-tightness, gamma radiation shielding performance, elasticity and workability required for the cable penetrations in a nuclear power plant and they generate noxious gases neither. (Kawakami, Y.)

Active control of noise radiation from vibrating structures

DEFF Research Database (Denmark)

Mørkholt, Jakob

developed, based on the theory of radiation filters for estimating the sound radiation from multimodal vibrations. This model has then been used in simulations of optimal feedback control, with special emphasis of the stability margins of the optimal control scheme. Two different methods of designing...... optimal and robust discrete-time feedback controllers for active vibration control of multimodal structures have been compared. They have been showed to yield controllers with identical frequency response characteristics, even though they employ completely different methods of numerical solutions...... and result in different representations of the controllers. The Internal Model Control structure combined with optimal filtering is suggested as an alternative to state space optimal control techniques for designing robust optimal controllers for audio frequency vibration control of resonant structures....

Nicotinamide and other benzamide analogs as agents for overcoming hypoxic cell radiation resistance in tumours

International Nuclear Information System (INIS)

Horsman, M.

1996-01-01

Oxygen deficient hypoxic cells, which are resistant to sparsely ionising radiation, have now been identified in most animal and some human solid tumours and will influence the response of those tumours to radiation treatment. This hypoxia can be either chronic, arising from an oxygen diffusion limitation, or acute, resulting from transient stoppages in microregional blood flow. Extensive experimental studies, especially in the last decade, have shown that nicotinamide and structurally related analogs can effectively sensitize murine tumours to both single and fractionated radiation treatments and that they do so in preference to the effects seen in mouse normal tissues. The earliest studies suggested that this enhancement of radiation damage was the result of an inhibition of the repair mechanisms. However, recent studies in mouse tumours have shown that these drugs prevent transient cessations in blood flow, thus inhibiting the development of acute hypoxia. This novel discovery led to the suggestion that the potential role of these agents as radiosensitizers would be when combined with treatments that overcame chronic hypoxia. The combined nicotinamide with hyperthermia proved that the enhancement of radiation damage by both agents together was greater than that seen with each agent alone. Similar results were later seen for nicotinamide combined with a perfluorochemical emulsion, carbogen breathing, and pentoxifylline, and in all these studies the effects in tumours were always greater than those seen in appropriate normal tissues. Of all the analogs, it is nicotinamide itself which has been the most extensively studied as a radiosensitizer in vivo and the one that shows the greatest effect in animal tumours. It is also an agent that has been well established clinically, with daily doses of up to 6 g, associated with a low incidence of side effects. This human dose is equivalent to 100-200 mg/kg in mice and such doses will maximally sensitize murine tumours to

Resistance of human erythrocytes containing elevated levels of vitamin E to radiation-induced hemolysis

International Nuclear Information System (INIS)

Brown, M.A.

1983-01-01

Human erythrocytes were isolated from the blood of healthy donors and then incubated in the presence of suspensions of alpha-tocopherol for 30 min at 37 degrees C. Unabsorbed tocopherol was removed by centrifugation using several washes of isotonic phosphate-buffered saline. Washed erythrocytes were resuspended to 0.05%. Hct and exposed to hemolyzing doses of 60 Co gamma radiation, and hemolysis was monitored continuously by light scattering at 700 nm in a recording spectrophotometer. The extent of hemolysis with time was sigmoid and data analysis was carried out on the time taken for 50% hemolysis to occur (t50%). The vitamin E content of erythrocytes was significantly elevated by the incubation procedure and resulted in the cells exhibiting a significantly increased resistance to hemolysis as reflected by the extended t50% values. Oral supplementation of 500 IU of vitamin E per day to eight normal human subjects for a period of 16 days also resulted in their washed erythrocytes exhibiting a significant increase in resistance to radiation-induced hemolysis. When comparing vitamin E incubated cells with control cells, both the dose-reducing factor (DRF) and the time for 50% hemolysis quotient (Qt50%) were observed to increase with increasing radiation dose

Track structure theory in radiobiology and in radiation detection

International Nuclear Information System (INIS)

Katz, R.

1978-01-01

The response of biological cells, and many physical radiation and track detectors to ionizing radiations and to energetic heavily ionizing particles, results from the secondary and higher generation electrons ejected from the atoms and molecules of the detector by the incident primary radiation. The theory uses a calculation of the radial distribution of local dose deposited by secondary electrons (delta-rays) from an energetic heavy ion as a transfer function, relating the dose-response relation measured (or postulated) for a particular detector in a uniform radiation field (gamma-rays) to obtain the radial distribution in response about the ion's path, and thus the structure of the track of a particle. Subsequent calculations yield the response of the detector to radiation fields of arbitrary quality. The models which have been used for detector response arise from target theory, and are of the form of statistical models called multi-hit or multi-target detectors, in which it is assumed that there are sensitive elements (emulsion grains, or biological cell nuclei) which may require many hits (emulsion grains) or single hits in different targets (say, cellular chromosomes) in order to produce the observed end-point. Recent work has demonstrated that many-hit physical detectors do exist. From both emulsion sensitometry and from the structure of tracks of heavy ions, it can be shown that emulsion-developer combinations exist which yield many-hit response. There is also some evidence that the supralinearity in thermoluminescent dosimeters arises from a mixture of 1-hit and 2-hit response, perhaps of different trap structures within the same TLD crystal. These detectors can be expected to mimic the response of biological cells to radiations of different quality. Their patterns of response may help us to understand better the structure of particle tracks in SSNTD's. (author)

High dose radiation damage in nuclear energy structural materials investigated by heavy ion irradiation simulation

International Nuclear Information System (INIS)

Zheng Yongnan; Xu Yongjun; Yuan Daqing

2014-01-01

Structural materials in ITER, ADS and fast reactor suffer high dose irradiations of neutrons and/or protons, that leads to severe displacement damage up to lOO dpa per year. Investigation of radiation damage induced by such a high dose irradiation has attracted great attention along with the development of nuclear energy facilities of new generation. However, it is deeply hampered for the lacking of high dose neutron and proton sources. Irradiation simulation of heavy ions produced by accelerators opens up an effective way for laboratory investigation of high dose irradiation induced radiation damage encountered in the ITER, ADS, etc. Radiation damage is caused mainly by atomic displacement in materials. The displacement rate of heavy ions is about lO 3 ∼10 7 orders higher than those of neutrons and protons. High displacement rate of heavy ions significantly reduces the irradiation time. The heavy ion irradiation simulation technique (HIIS) technique has been developed at China Institute of Atomic Energy and a series of the HIIS experiments have been performed to investigate radiation damage in stainless steels, tungsten and tantalum at irradiation temperatures from room temperature to 800 ℃ and in the irradiation dose region up to 100 dpa. The experimental results show that he radiation swelling peak for the modified stainless steel appears in the temperature region around 580 ℃ and the radiation damage is more sensitive to the temperature, the size of the radiation induced vacancy cluster or void increase with the increasing of the irradiation dose, and among the three materials the home-made modified stainless steel has the best radiation resistant property. (authors)

Fractionated irradiation of H69 small-cell lung cancer cells causes stable radiation and drug resistance with increased MRP1, MRP2, and topoisomerase IIα expression

International Nuclear Information System (INIS)

Henness, Sheridan; Davey, Mary W.; Harvie, Rozelle M.; Davey, Ross A.

2002-01-01

Purpose: After standard treatment with chemotherapy and radiotherapy, small-cell lung cancer (SCLC) often develops resistance to both treatments. Our aims were to establish if fractionated radiation treatment alone would induce radiation and drug resistance in the H69 SCLC cell line, and to determine the mechanisms of resistance. Methods and Materials: H69 SCLC cells were treated with fractionated X-rays to an accumulated dose of 37.5 Gy over 8 months to produce the H69/R38 subline. Drug and radiation resistance was determined using the MTT (3,-4,5 dimethylthiazol-2,5 diphenyltetrazolium bromide) cell viability assay. Protein expression was analyzed by Western blot. Results: The H69/R38 subline was resistant to radiation (2.0 ± 0.2-fold, p<0.0001), cisplatin (14 ± 7-fold, p < 0.001), daunorubicin (6 ± 3-fold, p<0.05), and navelbine (1.7 ± 0.15-fold, p<0.02). This was associated with increased expression of the multidrug resistance-associated proteins, MRP1 and MRP2, and topoisomerase IIα and decreased expression of glutathione-S-transferase π (GSTπ) and bcl-2 and decreased cisplatin accumulation. Treatment with 4 Gy of X-rays produced a 66% decrease in MRP2 in the H69 cells with no change in the H69/R38 cells. This treatment also caused a 5-fold increase in topoisomerase IIα in the H69/R38 cells compared with a 1.5-fold increase in the H69 cells. Conclusions: Fractionated radiation alone can lead to the development of stable radiation and drug resistance and an altered response to radiation in SCLC cells

Radiation shielding structure for concrete structure

International Nuclear Information System (INIS)

Oya, Hiroshi

1998-01-01

Crack inducing members for inducing cracks in a predetermined manner are buried in a concrete structure. Namely, a crack-inducing member comprises integrally a shielding plate and extended plates situated at the center of a wall and inducing plates vertically disposed to the boundary portion between them with the inducing plates being disposed each in a direction perforating the wall. There are disposed integrally a pair of the inducing plate spaced at a predetermined horizontal distance on both sides of the shielding plate so as to form a substantially crank-shaped cross section and extended plates formed in the extending direction of the shielding plate, and the inducing plates are disposed each in a direction perforating the wall. Then, cracks generated when stresses are exerted can be controlled, and generation of cracks passing through the concrete structure can be prevented reliably. The reliability of a radiation shielding effect can be enhanced remarkably. (N.H.)

Indirect radiation effects related to the environmental structure of targets

International Nuclear Information System (INIS)

Frankenberg, D.

1976-01-01

It is supposed, that in biological systems there are direct as well as indirect radiation effects. Their contributions to lethal effects depend mainly on two different kinds of structures within irradiated systems: the microscopic energy deposition patterns of radiation and the environmental structures of targets. The approach to determine these contributions of the lethal action of ionizing radiation in yeast cells was, to use chemical compounds, which specifically change the radical spectrum of water radiolysis. The efficiency of such chemical compounds in scavenging specifically water radicals was tested in aqueous solutions of thymine molecules, in which indirect radiation effects occur exclusively. The main result is, that the OH'-radical is by far the most effective radical to destroy thymine molecules. The relative contributions of direct and indirect radiation effects to lethal actions of ionizing radiation was investigated in yeast cells. The radical spectrum of water radiolysis was changed by bubbling the cell suspensions with different gases. The main result is, that there are no lethal radiation effects du to the action of water radicals

Radiation effects evaluation for electrons sheaf in packages resistance in a Lasioderma serricorne, Plodia interpunctella and Sitophilus zeamais; Avaliacao dos efeitos da radiacao por feixe de eletrons na resistencia de embalagens a Lasioderma serricorne, Plodia interpunctella e Sitophilus zeamais

Energy Technology Data Exchange (ETDEWEB)

Alves, Juliana Nazare

2011-07-01

The plagues of stored products consist of a man problem, depreciating products and causing economical damages. Among these curses we have Lasioderma serricorne (F. 1792), Sitophilus zeamais (M. 1855) and Plodia interpunctella (H. 1813) known by infesting stored products as: grains, brans, flours, coffee, tobacco, dried fruits and spices. These curses perforate and penetrate the packages, ovipositing over the substratum. In this context the package plays a fundamental part, preventing the contact and curses' proliferation in the packed product. So, to protect the packed product and to prolong its shelf life, the package should have good mechanical resistance to tension and perforation, good sealing, good barrier properties and should not transfer odors nor strange flavors to the packed product. The ionizing radiation can cause structural changes in polymer packages, these changes are caused by the scission processes and reticulation of the polymers chains. These are concurrent processes and the predominance of one over the other depends on the chemical structure of the polymer, the irradiation conditions and specific factors of the material that will absorb the energy. This work had the objective to evaluate the changes in mechanical properties of package structures used to store granola, cereal bar and pasta, as well as its resistance to perforation by L. serricorne, P. interpunctella and S. zeamais, when submitted to electrons sheaf radiation. In this methodology were used five structures of commercially utilized packages to store granola, cereal bar and pasta composed by (Polypropylene bi-oriented metallic/Polypropylene bi-oriented coextruded - BOPPmet/BOPP 50 {mu}m), (Polypropylene bi-oriented/Polypropylene - BOPP/PP 50 {mu}m), Poli (ethylene terephthalate) metallic/Polypropylene bi-oriented coextruded - PETmet/BOPP 32 {mu}m), Poli (ethylene terephthalate) /Polypropylene - PET/PP1 72 {mu}m), Poli (ethylene terephthalate)/Polypropylene - PET/PP2 32 {mu

Studies of antibiotic resistant mutants of Bacteroides fragilis obtained by Cs-137 ionizing radiation

International Nuclear Information System (INIS)

Azghani, A.O.

1986-01-01

The genus Bacteroides is an obligate anaerobic bacillus normally found in the upper respiratory tract, the colon, and the genitourinary system. The project reported here was undertaken because of the high frequency of hospital infections attributed to B. fragilis, and the increased resistance of the bacteria to commonly used antibiotics. Cs-137 gamma irradiation was used to induce antibiotic resistant mutants in B. fragilis in the presence of Escherichia coli B/r membrane fragments, employed as reducing agent. Based on a dose-survival curve, an effective radiation dose of 1.54 x 10 4 R (3.99 C/Kg) was used to induce mutations to rifampicin and tetracycline resistance in the test organism. The antibiotic resistant mutants of B. fragilis were utilized to reveal the mechanism by which this group of organisms becomes resistant to select chemotherapeutic agents. Studies on tetracycline resistant mutants of B. fragilis isolated after irradiation, suggest that the resistance to this antibiotic is associated with the outer membrane permeability. The difference in inhibitory action of rifampicin on RNA polymerase activity, from rifampicin sensitive and resistant strains of B. fragilis, reveals that this enzyme is a possible suitable target for inhibition of bacterial growth in anaerobes by rifampicin

Electrical Characterization of Defects Created by γ-Radiation in HfO2-Based MIS Structures for RRAM Applications

Science.gov (United States)

García, H.; González, M. B.; Mallol, M. M.; Castán, H.; Dueñas, S.; Campabadal, F.; Acero, M. C.; Sambuco Salomone, L.; Faigón, A.

2018-04-01

The γ-radiation effects on the electrical characteristics of metal-insulator-semiconductor capacitors based on HfO2, and on the resistive switching characteristics of the structures have been studied. The HfO2 was grown directly on silicon substrates by atomic layer deposition. Some of the capacitors were submitted to a γ ray irradiation using three different doses (16 kGy, 96 kGy and 386 kGy). We studied the electrical characteristics in the pristine state of the capacitors. The radiation increased the interfacial state densities at the insulator/semiconductor interface, and the slow traps inside the insulator near the interface. However, the leakage current is not increased by the irradiation, and the conduction mechanism is Poole-Frenkel for all the samples. The switching characteristics were also studied, and no significant differences were obtained in the performance of the devices after having been irradiated, indicating that the fabricated capacitors present good radiation hardness for its use as a RS element.

Radiation-thermal transformation of degraded oils

International Nuclear Information System (INIS)

Guliyeva, N.G.; Aliyeva, S.F.

2010-01-01

Full text :In order to elucidate the role of radiation in the process of oil degradation in the environment, and to identify opportunities for application of radiation-chemical technology to clean oil-contaminated soil were studied some regularities of radiation-chemical transformations of oil samples taken from wells, as well as after long-term presence on the surface of the water and soil. The most high radiation resistances of oil are samples taken from surface water. This is due to structural changes in the process of oil degradation, namely an increase in their part of the radiation-resistant resins and aspartames. This is due to evaporation of light hydrocarbons and heavy destructive transformations under the influence of oxygen, microorganisms, as well as components of the surface layer of soil. This phenomenon is explained by the specificity of action of the beam of accelerated electrons, namely the possible heating of the reaction zone due to inhibition of the electron. In this case the acceleration of diffusion processes results in an increase in the yield of gases.

Heavy irradiation effects in radiation-resistant optical fibers

Energy Technology Data Exchange (ETDEWEB)

Shikama, Tatsuo [Tohoku Univ., Oarai, Ibaraki (Japan). Oarai Branch, Inst. for Materials Research

1998-07-01

Development of a system for optical measurements in a nuclear reactor has been progressing to investigate dynamic changes in a material caused by heavy irradiation. In such system, transfer of optical signals to out-pile measuring systems is being attempted by the use of optical fibers. In this report, the characteristics of optical fibers in the heavy irradiation field were summarized. It has been known that amorphous silica might produce radiolysis and structural defects by the exposure to ionizing radiation. The effects of heavy irradiation on molten silica were extremely complicated. A large intensity of visible light absorption occurred from an early time during start-up of the reactor. The absorption range was limited below 700 nm for the radiation associating fast neutron and the absorption was mostly attributed to non-bridging oxygen hole center. The depletion of optical transferring capacity under the radiation might be related to the internal stress. Therefore, it seems desirable to use optical fibers in the conditions without leading too much stress. (M.N.)

The Survival and Resistance of Halobacterium salinarum NRC-1, Halococcus hamelinensis, and Halococcus morrhuae to Simulated Outer Space Solar Radiation.

Science.gov (United States)

Leuko, S; Domingos, C; Parpart, A; Reitz, G; Rettberg, P

2015-11-01

Solar radiation is among the most prominent stress factors organisms face during space travel and possibly on other planets. Our analysis of three different halophilic archaea, namely Halobacterium salinarum NRC-1, Halococcus morrhuae, and Halococcus hamelinensis, which were exposed to simulated solar radiation in either dried or liquid state, showed tremendous differences in tolerance and survivability. We found that Hcc. hamelinensis is not able to withstand high fluences of simulated solar radiation compared to the other tested organisms. These results can be correlated to significant differences in genomic integrity following exposure, as visualized by random amplified polymorphic DNA (RAPD)-PCR. In contrast to the other two tested strains, Hcc. hamelinensis accumulates compatible solutes such as trehalose for osmoprotection. The addition of 100 mM trehalose to the growth medium of Hcc. hamelinensis improved its survivability following exposure. Exposure of cells in liquid at different temperatures suggests that Hbt. salinarum NRC-1 is actively repairing cellular and DNA damage during exposure, whereas Hcc. morrhuae exhibits no difference in survival. For Hcc. morrhuae, the high resistance against simulated solar radiation may be explained with the formation of cell clusters. Our experiments showed that these clusters shield cells on the inside against simulated solar radiation, which results in better survival rates at higher fluences when compared to Hbt. salinarum NRC-1 and Hcc. hamelinensis. Overall, this study shows that some halophilic archaea are highly resistant to simulated solar radiation and that they are of high astrobiological significance. Halophiles-Solar radiation-Stress resistance-Survival.

A possible radiation-resistant solar cell geometry using superlattices

Science.gov (United States)

Goradia, C.; Clark, R.; Brinker, D.

1985-01-01

A solar cell structure is proposed which uses a GaAs nipi doping superlattice. An important feature of this structure is that photogenerated minority carriers are very quickly collected in a time shorter than bulk lifetime in the fairly heavily doped n and p layers and these carriers are then transported parallel to the superlattice layers to selective ohmic contacts. Assuming that these already-separated carriers have very long recombination lifetimes, due to their across an indirect bandgap in real space, it is argued that the proposed structure may exhibit superior radiation tolerance along with reasonably high beginning-of-life efficiency.

The origin of polarized blackbody radiation from resistively heated multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Aliev, Ali E.; Kuznetsov, Alexander A.

2008-01-01

We observed very pronounced polarization of light emitted by highly aligned free-standing multiwall carbon nanotube (MWNT) sheet in axial direction which is turned to the perpendicular polarization when a number of layers are increased. The radiation spectrum of resistively heated MWNT sheet closely follows to the Plank's blackbody radiation distribution. The obtained polarization features can be described by a classical dielectric cylindrical shell model, taking into consideration the contribution of delocalized π-electrons (π surface plasmons). In absorption (emission) the optical transverse polarizability, which is much smaller than longitudinal one, is substantially suppressed by depolarization effect due to screening by induced charges. This phenomenon suggests very simple and precise method to estimate the alignment of nanotubes in bundles or large assemblies

Discussion on the fracutre microscopic resistance by cleavage in structural steels

International Nuclear Information System (INIS)

Darwish, F.A.I.; Teixeira, J.C.G.; Ouro, C.R.

1982-01-01

An analysis on the physical significance of the microscopic resistance of a structural steel is presented. The theorethical and experimental aspects involved in the determination of this resistance are still presented. The results obtained with low, medium and high mechanical resistance are showed and discussed. (E.G.) [pt

Radiation swelling of steels with lath martensite-austenic structure

International Nuclear Information System (INIS)

Sagaradze, V.V.; Pavlov, V.A.; Alyab'ev, V.M.; Lapin, S.S.; Ermishkin, V.A.; Antonova, O.V.

1987-01-01

Influence of electron radiation in the column of the JEM-1000 electron microscope on radiation swelling of austenite as austenitic fields and thin plates surrounded by α-martensite crystals is investigated. Formation of lath structure of alternating dispersive plates of martensite and invert austenite formed as a result of partial inverse martensite transformation α→γ is shown to restrain radiation swelling and formation of vacancy voids in stainless steels

Defect kinetics and resistance to amorphization in zirconium carbide

International Nuclear Information System (INIS)

Zheng, Ming-Jie; Szlufarska, Izabela; Morgan, Dane

2015-01-01

To better understand the radiation response of zirconium carbide (ZrC), and in particular its excellent resistance to amorphization, we have used density functional theory methods to study the kinetics of point defects in ZrC. The migration barriers and recombination barriers of the simple point defects are calculated using the ab initio molecular dynamics simulation and the nudged elastic band method. These barriers are used to estimate C and Zr interstitial and vacancy diffusion and Frenkel pair recombination rates. A significant barrier for C Frenkel pair recombination is found but it is shown that a large concentration of C vacancies reduces this barrier dramatically, allowing facile healing of radiation damage. The mechanisms underlying high resistance to amorphization of ZrC were analyzed from the perspectives of structural, thermodynamic, chemical and kinetic properties. This study provides insights into the amorphization resistance of ZrC as well as a foundation for understanding general radiation damage in this material

Structural dynamic and resistance to nuclear air blast

International Nuclear Information System (INIS)

Qureshi, S.M.

2003-01-01

A need exists to design protective shelters attached to specialized facilities against nuclear airbursts, explosive shocks and impacting projectiles. Designing such structures against nuclear and missile impact is a challenging task that needs to be looked into for design methodology formulation and practicability. Structures can be designed for overpressure pulsed generated by a nuclear explosion as well as the scabbing and perforation/punching of an impacting projectile. This paper discuses and formulates the methods of dynamic analysis and design required to undertake such a task. Structural resistance to peak overpressure pulse for a 20 KT weapons and smaller tactical nuclear weapons of 1 KT (16 psi, overpressure) size as a direct air blast overpressure has been considered in design of walls, beams and slabs of a special structure under review. The design of shear reinforcement as lacing is also carried out. Adopting the philosophy of strengthening and hardening can minimize the effect of air blast overpressure and projectile impact. The objective is to avoid a major structural failure. The structure then needs to be checked against ballistic penetration by a range of weapons or be required to resist explosive penetration from the charge detonated in contact with the structure. There is also a dire need to formulate protective guidelines for all existing and future critical facilities. (author)

Ionizing-radiation resistance in the desiccation-tolerant cyanobacterium Chroococcidiopsis

Science.gov (United States)

Billi, D.; Friedmann, E. I.; Hofer, K. G.; Caiola, M. G.; Ocampo-Friedmann, R.

2000-01-01

The effect of X-ray irradiation on cell survival, induction, and repair of DNA damage was studied by using 10 Chroococcidiopsis strains isolated from desert and hypersaline environments. After exposure to 2.5 kGy, the percentages of survival for the strains ranged from 80 to 35%. In the four most resistant strains, the levels of survival were reduced by 1 or 2 orders of magnitude after irradiation with 5 kGy; viable cells were recovered after exposure to 15 kGy but not after exposure to 20 kGy. The severe DNA damage evident after exposure to 2.5 kGy was repaired within 3 h, and the severe DNA damage evident after exposure to 5 kGy was repaired within 24 h. The increase in trichloroacetic acid-precipitable radioactivity in the culture supernatant after irradiation with 2.5 kGy might have been due to cell lysis and/or an excision process involved in DNA repair. The radiation resistance of Chroococcidiopsis strains may reflect the ability of these cyanobacteria to survive prolonged desiccation through efficient repair of the DNA damage that accumulates during dehydration.

Effect of fractionated radiation on multidrug resistance in human ovarian cancer

International Nuclear Information System (INIS)

Kong Dejuan; Liu Xiaodong; Liang Bing; Jia Lili; Ma Shumei

2012-01-01

Objective: To investigate the effect of different subtypes of fractionated doses on multidrug resistance in ovarian cancer cells. Methods: The human ovarian cancer cell lines SKOV3 and its drug-resistant subtype SKVCR were divided into four groups i.e., sham-irradiated, single dose (10 Gy), fractionated dose (2 Gy × 5) and multi-fractionated dose (1 Gy × 2 × 5). Cell sensitivity to vincristine (VCR), etoposide (VP-16), pirarubicin (THP) and cisplatin (DDP) was measured by MTT assay. Western blot was applied to detect the expression of P-gp after irradiation. Results: The doubling time of SKVCR was about 1.8-fold of that of SKOV3 cells. P-gp was expressed in SKVCR but not in SKOV3. IC 50 values of SKVCR were higher than those of SKOV3. To SKOV3 cells, single dose irradiation decreased cell sensitivity to THP and DDP and fractionated irradiation decreased cell sensitivity to VCR, THP and VP-16. Multi-fractionated irradiation decreased cell sensitivity to VP-16. In SKVCR cells, all these irradiation treatments increased cell sensitivity to VCR and VP-16 but not to DDP. In addition, single and fractionated irradiation decreased P-gp expression in SKVCR cells. Conclusions: Single, fractionated and multi-fractionated radiation induced chemotherapy resistance in SKOV3 cells, while reversed drug resistance to VCR and VP-16 in SKVCR cells. (authors)

Radiation-resistant requirements analysis of device and control component for advanced spent fuel management process

Energy Technology Data Exchange (ETDEWEB)

Song, Tai Gil; Park, G. Y.; Kim, S. Y.; Lee, J. Y.; Kim, S. H.; Yoon, J. S. [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-02-01

It is known that high levels of radiation can cause significant damage by altering the properties of materials. A practical understanding of the effects of radiation - how radiation affects various types of materials and components - is required to design equipment to operate reliably in a gamma radiation environment. When designing equipment to operate in a high gamma radiation environment, such as will be present in a nuclear spent fuel handling facility, several important steps should be followed. In order to active test of the advanced spent fuel management process, the radiation-resistant analysis of the device and control component for active test which is concerned about the radiation environment is conducted. Also the system design process is analysis and reviewed. In the foreign literature, 'threshold' values are generally reported. the threshold values are normally the dose required to begin degradation in a particular material property. The radiation effect analysis for the device of vol-oxidation and metalization, which are main device for the advanced spent fuel management process, is performed by the SCALE 4.4 code. 5 refs., 4 figs., 13 tabs. (Author)

Theoretical and experimental investigation of atomic radiative lifetimes and hyperfine structures

International Nuclear Information System (INIS)

Joensson, Per.

1992-01-01

Atomic radiative lifetimes and hyperfine structures as well as other properties, such as total energy and specific mass shift, have been studied theoretically and experimentally. Computer programs to calculate hyperfine structure constants from non-relativistic multiconfiguration Hartree-Fock (MCHF) and relativistic multi-configuration Dirac-Fock (MCDF) wavefunctions have been written. Using these programs large-scale calculations of hyperfine structures in lithium and sodium have been performed. It is shown, that the MCHF method is able to predict hyperfine structures to an accuracy of a few per mille in lithium, whereas for the more complex hyperfine structures to an accuracy of a few per mille in lithium, whereas for the more complex sodium atom an accuracy of a few per cent is obtainable. For lithium convergence of the total energy, ionization energy, specific mass shift and hyperfine parameters has been studied with the MCHF method. Radiative lifetimes and hyperfine structures of excited states in sodium and silver have been experimentally determined using time-resolved laser spectroscopy. By recording the fluorescence light decay curves following VUV excitation, the radiative lifetimes and hyperfine structures of the 7p 2 P states in silver were measured. The delayed-coincidence technique has been used to make very accurate measurements of the radiative lifetimes and hyperfine structures of the lowest P states in sodium and silver

Multi-functional layered structure having structural and radiation shielding attributes

Science.gov (United States)

Kaul, Raj K. (Inventor); Barghouty, Abdulnasser Fakhri (Inventor); Penn, Benjamin G. (Inventor); Hulcher, Anthony Bruce (Inventor)

2010-01-01

A cosmic and solar radiation shielding structure that also has structural attributes is comprised of three layers. The first layer is 30-42 percent by volume of ultra-high molecular weight (UHMW) polyethylene fibers, 18-30 percent by volume of graphite fibers, and a remaining percent by volume of an epoxy resin matrix. The second layer is approximately 68 percent by volume of UHMW polyethylene fibers and a remaining percent by volume of a polyethylene matrix. The third layer is a ceramic material.

Ferrites based infrared radiation coatings with high emissivity and high thermal shock resistance and their application on energy-saving kettle

International Nuclear Information System (INIS)

Zhang, Jianyi; Fan, Xi’an; Lu, Lei; Hu, Xiaoming; Li, Guangqiang

2015-01-01

Highlights: • The ferrites based infrared radiation coating was prepared by HVOF for the first time. • The infrared radiation coatings were applied firstly on the household kettle. • The bonding strength between the coating and substrate could reach 30.7 MPa. • The coating kept intact when cycle reached 27 by quenching from 1000 °C using water. • The energy-saving efficiency of the kettle with coating could reach 30.5%. - Abstract: Starting from Fe 2 O 3 , MnO 2 , Co 2 O 3 and NiO powders, the ferrites based infrared radiation coatings with high emissivity and high thermal shock resistance were successfully prepared on the surface of carbon steel by high velocity oxy-fuel spraying (HVOF). The coating thickness was about 120–150 μm and presented a typical flat lamellar structure. The coating surface was rough and some submicron grade grains distributed on it. The infrared emissivity of the ferrites based coating by HVOF was over 0.74 in 3–20 μm waveband at 800 °C, which was obviously higher than that of the coating by brushing process in the short waveband. The bonding strength was 30.7 MPa between the coating and substrate, which was five times more than that of conventional coatings by brushing process. The combined effect of the superior bonding strength, typical lamellar structure, pre-existing microcracks and newly generated pores made the cycle times reach 27 when the coating samples were quenched from 1000 °C using water. Lastly, the infrared radiation coatings were applied on the underside of household kettle, and the energy-saving efficiency could reach 30.5%. The ferrites based infrared radiation coatings obtained in this work are good candidates for saving energy in the field of cookware and industrial high temperature furnace

Radiation resistant PIDECα cell using photon intermediate direct energy conversion and a 210Po source.

Science.gov (United States)

Weaver, Charles L; Schott, Robert J; Prelas, Mark A; Wisniewski, Denis A; Rothenberger, Jason B; Lukosi, Eric D; Oh, Kyuhak

2018-02-01

Radiation damage is a significant concern with both alphavoltaic and betavoltaic cells because their performance degrades, especially with high-energy - (>200keV) beta and alpha particles. Indirect excitation methods, such as the Photon Intermediate Direct Energy Conversion (PIDEC) framework, can protect the transducer from radiation. A nuclear battery using a 90 Sr beta source was constructed by the author's research group, which demonstrated the radiation resistance of a PIDEC cell driven by beta particles (PIDECβ cell). Use of alpha sources to drive nuclear batteries would appear to be much more attractive than beta sources due to higher potential power density. However, they are also subject to higher rates of radiation damage. This paper describes the successful incorporation of alpha particles into the PIDEC framework using the alpha emitter 210 Po to form a PIDECα cell. The PIDECα cell transducer was exposed to alpha particles for over one year without experiencing adverse effects from radiation damage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Oxidation resistance coating for niobium base structural composites

International Nuclear Information System (INIS)

Tabaru, T.; Shobu, K.; Kim, J.H.; Hirai, H.; Hanada, S.

2003-01-01

Oxidation behavior of Al-rich Mo(Si,Al) 2 base alloys, which is a candidate material for the oxidation resistance coating on Nb base structural composites, were investigated by thermogravimetry. The Mo(Si,Al) 2 base alloys containing Mo 5 (Si,Al) 3 up to about 10 vol% exhibits excellent oxidation resistance at temperatures ranging from 780 to 1580 K, particularly at 1580 K due to continuous Al 2 O 3 layer development. To evaluate the applicability of the Mo(Si,Al) 2 base coating, plasma spraying on Nb base composites were undertaken. However, interface reaction layer was found to form during the following heat treatment. Preparation of Mo(Si,Al) 2 /Al 2 O 3 /Nb layered structures via powder metallurgical process was attempted to preclude diffusion reaction between coating and substrate. (orig.)

Inferring the interaction structure of resistance to antimicrobials.

Science.gov (United States)

Zawack, Kelson; Love, Will; Lanzas, Cristina; Booth, James G; Gröhn, Yrjö T

2018-04-01

The growth of antimicrobial resistance presents a significant threat to human and animal health. Of particular concern is multi-drug resistance, as this increases the chances an infection will be untreatable by any antibiotic. In order to understand multi-drug resistance, it is essential to understand the association between drug resistances. Pairwise associations characterize the connectivity between resistances and are useful in making decisions about courses of treatment, or the design of drug cocktails. Higher-order associations, interactions, which tie together groups of drugs can suggest commonalities in resistance mechanism and lead to their identification. To capture interactions, we apply log-linear models of contingency tables to analyze publically available data on the resistance of Escheresia coli isolated from chicken and turkey meat by the National Antimicrobial Resistance Monitoring System. Standard large sample and conditional exact testing approaches for assessing significance of parameters in these models breakdown due to structured patterns inherent to antimicrobial resistance. To address this, we adopt a Bayesian approach which reveals that E. coli resistance associations can be broken into two subnetworks. The first subnetwork is characterized by a hierarchy of β-lactams which is consistent across the chicken and turkey datasets. Tier one in this hierarchy is a near equivalency between amoxicillin-clavulanic acid, ceftriaxone and cefoxitin. Susceptibility to tier one then implies susceptibility to ceftiofur. The second subnetwork is characterized by more complex interactions between a variety of drug classes that vary between the chicken and turkey datasets. Copyright © 2018 Elsevier B.V. All rights reserved.

Radiation-induced structural changes, (2)

International Nuclear Information System (INIS)

Ogasawara, M.; Matsuyama, T.

1992-11-01

This seminar is aimed at understanding both the physical and chemical aspects of the structural changes of materials induced by photons or ionizing radiation. The seminar was held on December 19th, 1991 and from February 13 to 14th, 1992 in this institute. The most active areas of the material science, in addition to the previous subjects, such as organic superconductors, silicon-based polymers, and fullerenes were included in this seminar. (J.P.N.)

Tamper and radiation resistant instrumentation for safeguarding special nuclear materials

International Nuclear Information System (INIS)

Parsons, B.B.; Wells, J.L.

1977-01-01

A tamper-resistant liquid level/accountability instrumentation system for safeguards use has been developed and tested. The tests demonstrate the accuracy of liquid level measurement using TDR (Time Domain Reflectometry) techniques and the accuracy of differential pressure and temperature measurements utilizing a custom designed liquid level sensor probe. The calibrated liquid level, differential pressure, and temperature data provide sufficient information to accurately determine volume, density, and specific gravity. Test solutions used include ordinary tap water, diluted nitric acid in varying concentrations, and diluted uranium trioxide also in varying concentrations. System operations and preliminary test results conducted at the General Electric Midwest Fuel Recovery Plant and the National Bureau of Standards, respectively, suggest that the system will provide the safeguards inspector with an additional tool for real-time independent verification of normal operations and special nuclear materials accountancy data for chemical reprocessing plants. This paper discusses the system design concepts, including a brief description of the tamper and radiation resistant features, the preliminary test results, and the significance of the work

Resistive foil edge grading for accelerator and other high voltage structures

Science.gov (United States)

Caporaso, George J.; Sampayan, Stephen F.; Sanders, David M.

2014-06-10

In a structure or device having a pair of electrical conductors separated by an insulator across which a voltage is placed, resistive layers are formed around the conductors to force the electric potential within the insulator to distribute more uniformly so as to decrease or eliminate electric field enhancement at the conductor edges. This is done by utilizing the properties of resistive layers to allow the voltage on the electrode to diffuse outwards, reducing the field stress at the conductor edge. Preferably, the resistive layer has a tapered resistivity, with a lower resistivity adjacent to the conductor and a higher resistivity away from the conductor. Generally, a resistive path across the insulator is provided, preferably by providing a resistive region in the bulk of the insulator, with the resistive layer extending over the resistive region.

Radiation polymerizable compositions

International Nuclear Information System (INIS)

Goff, D.L.; Yuan, E.L.; Proskow, S.

1982-01-01

A polyamide ester resin containing photopolymerizable groups is made more rapidly photopolymerizable and therefore more suitable for forming relief structures on electrical devices (such as capacitors, integrated circuits and semiconductors) by including therein a solvent, a radiation-sensitive polymerizable polyfunctional acrylate compound and an aromatic biimidazole photopolymerization initiator. On exposure through a pattern of a dried film obtained using a solution of such composition, photopolymerization takes place rapidly and efficiently following which developing can be effected and the photopolymerized material baked to leave a heat-resistant polyimide structure. (author)

Galactic structure and gamma radiation

International Nuclear Information System (INIS)

Casse, Michel; Cesarsky, Catherine; Paul Jacques

1977-01-01

A model of spiral structure of the Galaxy is outlined from radiosynchrotron and gamma observations. The most interesting observations in the galactic context, obtained by the SAS II American satellite are concerned with the distribution of the γ photoemission at energies higher than 10 8 eV, along the galactic equator. The model proposed is in quantitative agreement with the present ideas on the spiral structure of the Galaxy, the galactic magnetic field, and the confinement of cosmic rays by the magnetic field and of the magnetic field by matter. Following the American era, the European COS-B satellite opens the European phase towards an identification of the discrete gamma radiation sources [fr

Dual responsive promoters to target therapeutic gene expression to radiation-resistant hypoxic tumor cells

International Nuclear Information System (INIS)

Chadderton, Naomi; Cowen, Rachel L.; Sheppard, Freda C.D.; Robinson, Suzanne; Greco, Olga; Scott, Simon D.; Stratford, Ian J.; Patterson, Adam V.; Williams, Kaye J.

2005-01-01

Purpose: Tumor hypoxia is unequivocally linked to poor radiotherapy outcome. This study aimed to identify enhancer sequences that respond maximally to a combination of radiation and hypoxia for use in genetic radiotherapy approaches. Methods and materials: The influence of radiation (5 Gy) and hypoxia (1% O 2 ) on reporter-gene expression driven by hypoxia (HRE) and radiation (Egr-1) responsive elements was evaluated in tumor cells grown as monolayers or multicellular spheroids. Hypoxia-inducible factor-1α (HIF-1α) and HIF-2α protein expression was monitored in parallel. Results: Of the sequences tested, an HRE from the phosphoglycerate kinase-1 gene (PGK-18[5+]) was maximally induced in response to hypoxia plus radiation in all 5 cell lines tested. The additional radiation treatment afforded a significant increase in the induction of PGK-18[5+] compared with hypoxia alone in 3 cell lines. HIF-1α/2α were induced by radiation but combined hypoxia/radiation treatment did not yield a further increase. The dual responsive nature of HREs was maintained when spheroids were irradiated after delivery of HRE constructs in a replication-deficient adenovirus. Conclusions: Hypoxia-responsive enhancer element sequences are dually responsive to combined radiation and hypoxic treatment. Their use in genetic radiotherapy in vivo could maximize expression in the most radio-resistant population at the time of radiation and also exploit microenvironmental changes after radiotherapy to yield additional switch-on

Effect of structure state on the microplastic resistance of thermobimetals

International Nuclear Information System (INIS)

Bashnin, Yu.A.; Ulanovskij, F.B.; Shiryaeva, A.N.

1983-01-01

The effect of structural state on microplastic resistance of nickel alloy thermobimetals with butt oint of layers has been studied. It has been shown that a stable polygonal structure with minimum level of residual stresses is achieved in thermobimetals by a three-fold thermocyclic treatment with heating up to 400 deg C, holding during 1 hour and slow cooling up to room temperature after each cycle with a speed of 2-4 deg C per min. The stable polygonal structure of alloys-components of thermobimetals provides growth of microplastic resistance and drop of residual deflection. The maximum thermobimetal thermosensitivity is provided at 50% preliminary plastic deformation degree on thermocouples cut out along the direction of rolli

Effect of structure state on the microplastic resistance of thermobimetals

Energy Technology Data Exchange (ETDEWEB)

Bashnin, Yu.A.; Ulanovskij, F.B.; Shiryaeva, A.N. (Moskovskij Vechernij Metallurgicheskij Inst. (USSR))

1983-01-01

The effect of structural state on microplastic resistance of nickel alloy thermobimetals with butt joint of layers has been studied. It has been shown that a stable polygonal structure with minimum level of residual stresses is achieved in thermobimetals by a three-fold thermocyclic treatment with heating up to 400 deg C, holding during 1 hour and slow cooling up to room temperature after each cycle with a speed of 2-4 deg C per min. The stable polygonal structure of alloys-components of thermobimetals provides growth of microplastic resistance and drop of residual deflection. The maximum thermobimetal thermosensitivity is provided at 50% preliminary plastic deformation degree on thermocouples cut out along the direction of rolli.

Preparation and characteristics of a flexible neutron and γ-ray shielding and radiation-resistant material reinforced by benzophenone

Directory of Open Access Journals (Sweden)

Pin Gong

2018-04-01

Full Text Available With a highly functional methyl vinyl silicone rubber (VMQ matrix and filler materials of B4C, PbO, and benzophenone (BP and through powder surface modification, silicone rubber mixing, and vulcanized molding, a flexible radiation shielding and resistant composite was prepared in the study. The dispersion property of the powder in the matrix filler was improved by powder surface modification. BP was added into the matrix to enhance the radiation resistance performance of the composites. After irradiation, the tensile strength, elongation, and tear strength of the composites decreased, while the Shore hardness of the composites and the crosslinking density of the VMQ matrix increased. Moreover, the composites with BP showed better mechanical properties and smaller crosslinking density than those without BP after irradiation. The initial degradation temperatures of the composites containing BP before and after irradiation were 323.6°C and 335.3°C, respectively. The transmission of neutrons for a 2-mm thick sample was only 0.12 for an Am–Be neutron source. The transmission of γ-rays with energies of 0.662, 1.173, and 1.332 MeV for 2-cm thick samples were 0.7, 0.782, and 0.795, respectively. Keywords: Flexible Composite, Neutron Shielding, Radiation Resistance, γ-ray Shielding

Thermal/structural analysis of radiators for heavy-duty trucks

International Nuclear Information System (INIS)

Mao Shaolin; Cheng, Changrui; Li Xianchang; Michaelides, Efstathios E.

2010-01-01

A thermal/structural coupling approach is applied to analyze thermal performance and predict the thermal stress of a radiator for heavy-duty transportation cooling systems. Bench test and field test data show that non-uniform temperature gradient and dynamic pressure loads may induce large thermal stress on the radiator. A finite element analysis (FEA) tool is used to predict the strains and displacement of radiator based on the solid wall temperature, wall-based fluid film heat transfer coefficient and pressure drop. These are obtained from a computational fluid dynamics (CFD) simulation. A 3D simulation of turbulent flow and coupled heat transfer between the working fluids poses a major difficulty because the range of length scales involved in heavy-duty radiators varies from few millimeters of the fin pitch and/or tube cross-section to several meters for the overall size of the radiator. It is very computational expensive, if not impossible, to directly simulate the turbulent heat transfer between fins and the thermal boundary layer in each tube. In order to overcome the computational difficulties, a dual porous zone (DPZ) method is applied, in which fins in the air side and turbulators in the water side are treated as porous region. The parameters involved in the DPZ method are tuned based on experimental data in prior. A distinguished advantage of the porous medium method is its effectiveness of modeling wide-range characteristic scale problems. A parametric study of the impact of flow rate on the heat transfer coefficient is presented. The FEA results predict the maximum value of stress/strain and target locations for possible structural failure and the results obtained are consistent with experimental observations. The results demonstrate that the coupling thermal/structural analysis is a powerful tool applied to heavy-duty cooling product design to improve the radiator thermal performance, durability and reliability under rigid working environment.

Assessment of the radiation resistance of some aromatic polyesters

International Nuclear Information System (INIS)

Choi, E.J.; Hill, D.J.T.; Kim, K.Y.

1998-01-01

Full text: For many applications, polyesters have more useful properties than vinyl polymers, and they can be degraded to their monomer components and recycled. In addition, aromatic polyesters are known to display a resistance to high temperatures and high-energy ionizing radiation. Recently, we have reported the γ-radiolysis for some aromatic polyesters at low radiation dose; The G-values of radical formation at 77 K were determined to be in the range 0.38∼0.46 for the polyesters of bisphenol A with fluorine substitution at isopropylidene units and in the range 0.71∼1.18 for the polyesters of halogenated bisphenol A with decamethylene segments. While the radiation sensitivities of the latter polymers were dependent on the position and content of halogen substitution, those of the former polymers were slightly dependent on these factors as assessed by the G-values at 77 K. We also have studied the radiolysis of the commercial aromatic polyesters (UP) and polycarbonate (PC). UP has been found to be more radiation stable than PC with respect to the total yield of radicals formed. The G-values for radical formation at 77K was determined to be 0.31 and 0.5 for UP and PC, respectively. In this work, we have prepared poly(ethylene-, butylene- or decalene-terephthalate)s (PET, PBT or PDT) and poly(ethylene-, buthylene- or decalene-2,6-naphthalenedicarboxylate)s (PEN, PBN or PDN) by standard melt polymerization methods, and have examined their γ-radiolysis at 77 K or room temperature, and in vacuum or air, through the applications of ESR spectroscopy and thermal analysis. Inherent viscosities of the polyesters used for the radiation studies were in the range of 0.16∼0.69 dL/g. The values of G(R) indicates that PEN-related polymers have more radiation stable than PET-related polymers and the E, B and D order is one of decreasing stability as one might expect. The significant decrease in the G(R)-values of the polyester being in the range of 0.1∼0.41 at 77 K by

Compact synchrotron radiation depth lithography facility

Science.gov (United States)

Knüppel, O.; Kadereit, D.; Neff, B.; Hormes, J.

1992-01-01

X-ray depth lithography allows the fabrication of plastic microstructures with heights of up to 1 mm but with the smallest possible lateral dimensions of about 1 μm. A resist is irradiated with ``white'' synchrotron radiation through a mask that is partially covered with x-ray absorbing microstructures. The plastic microstructure is then obtained by a subsequent chemical development of the irradiated resist. In order to irradiate a reasonably large resist area, the mask and the resist have to be ``scanned'' across the vertically thin beam of the synchrotron radiation. A flexible, nonexpensive and compact scanner apparatus has been built for x-ray depth lithography at the beamline BN1 at ELSA (the 3.5 GeV Electron Stretcher and Accelerator at the Physikalisches Institut of Bonn University). Measurements with an electronic water level showed that the apparatus limits the scanner-induced structure precision to not more than 0.02 μm. The whole apparatus is installed in a vacuum chamber thus allowing lithography under different process gases and pressures.

Ionizing radiations in Italian health care structures

International Nuclear Information System (INIS)

Fizzano, M.R.; Frusteri, L.

2006-01-01

The Council of the European Union has completely renewed the framework regarding radiation protection by adopting some directives: Directive 97/43 EURATOM lays down the general principles of the radiation protection of individuals undergoing exposure to ionising radiations related to medical exposures, as a supplement of Directive 96/29 EURATOM laying down the basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiations.The incorporation into Italian legislation of the European Community directives on the improvement of health and safety at work has promoted a vast effort in order to revise the surveillance approach in many facilities, including hospitals. In Italy, safety law is referred to every workplace; anyway the use of ionising radiations is ruled by specific laws. So in the health care structures it is necessary integrating both the laws and this process is often difficult to carry on. The Italian Legislative Decree 230/95, one the main laws that aim to protect workers against ionising radiations, introduced Directive 96/29/EURATOM. This Decree asks that a doctor and a technical expert analyse the workplace and classify area and workers in according to dose of ionising radiation established by law. The Italian Legislative Decree 626/94 asks that risk analysis in general is made by doctor and specialist in risk. So, in case of risk from ionising radiation, all these figures have to cooperate in order to make an evaluation risk document. (N.C.)

Ionizing radiations in Italian health care structures

Energy Technology Data Exchange (ETDEWEB)

Fizzano, M.R.; Frusteri, L. [Technical Advisory Dept. for Risk Assessment and Prevention, Italian Workers Compensation Authority, Rome (Italy)

2006-07-01

The Council of the European Union has completely renewed the framework regarding radiation protection by adopting some directives: Directive 97/43 EURATOM lays down the general principles of the radiation protection of individuals undergoing exposure to ionising radiations related to medical exposures, as a supplement of Directive 96/29 EURATOM laying down the basic safety standards for the protection of the health of workers and the general public against the dangers arising from ionising radiations.The incorporation into Italian legislation of the European Community directives on the improvement of health and safety at work has promoted a vast effort in order to revise the surveillance approach in many facilities, including hospitals. In Italy, safety law is referred to every workplace; anyway the use of ionising radiations is ruled by specific laws. So in the health care structures it is necessary integrating both the laws and this process is often difficult to carry on. The Italian Legislative Decree 230/95, one the main laws that aim to protect workers against ionising radiations, introduced Directive 96/29/EURATOM. This Decree asks that a doctor and a technical expert analyse the workplace and classify area and workers in according to dose of ionising radiation established by law. The Italian Legislative Decree 626/94 asks that risk analysis in general is made by doctor and specialist in risk. So, in case of risk from ionising radiation, all these figures have to cooperate in order to make an evaluation risk document. (N.C.)

Active structural acoustic control for reduction of radiated sound from structure

International Nuclear Information System (INIS)

Hong, Jin Seok; Oh, Jae Eung

2001-01-01

Active control of sound radiation from a vibrating rectangular plate by a steady-state harmonic point force disturbance is experimentally studied. Structural excitation is achieved by two piezoceramic actuators mounted on the panel. Two accelerometers are implemented as error sensors. Estimated radiated sound signals using vibro-acoustic path transfer function are used as error signals. The vibro-acoustic path transfer function represents system between accelerometers and microphones. The approach is based on a multi-channel filtered-x LMS algorithm. The results shows that attenuation of sound levels of 11dB, 10dB is achieved

PROSPECTIVE EVALUATION OF AN IN VITRO RADIATION RESISTANCE ASSAY IN LOCALLY ADVANCED CANCER OF THE UTERINE CERVIX: A SOUTHWEST ONCOLOGY GROUP STUDY

Science.gov (United States)

Randall, Leslie M; Monk, Bradley J; Moon, James; Parker, Ricardo; Al-Ghazi, Muthana; Wilczynski, Sharon; Fruehauf, John P; Markman, Maurie; Burger, Robert A

2010-01-01

Objectives To investigate the feasibility of performing a fresh-tissue, in vitro radiation resistance assay (IVRRA) in a cooperative group setting and to assess the association of IVRRA results with clinical outcomes. Methods Women with Stages IIB-IVA carcinoma of the uterine cervix without obvious para-aortic lymphadenopathy on imaging were eligible. Primary tumor biopsies were shipped to a central testing facility where agar-based cell suspensions were exposed to 300 cGy of RT ± cisplatin and cultured for 5 days. 3H-thymidine incorporation was used to determine percent cell inhibition (PCI) of test specimen compared to that of the untreated control. Tumors were considered to exhibit extreme radiation resistance (ERR), intermediate radiation resistance (IRR) or low radiation resistance (LRR) based on a standard data set from 39 previously studied specimens. Standardized doses of external beam radiation and intracavitary brachytherapy, when feasible, in addition to platinum-based chemotherapy were mandated. Progression-free survival (PFS) was the primary endpoint. Clinical response and overall survival (OS) were secondary endpoints. Clinical investigators were blinded to assay data and vice versa. Results Thirty-six patients were enrolled, but analysis was limited to 17 patients whose specimens were adequate for IVRRA. The median follow-up time was 40 months. There was no association between IVRRA and response. In the Cox model, IRR/ERR tumors showed worse PFS [HR=11.2 (95% CI 1.3–96, p=0.03)] and worse OS [HR=11.7 (95% CI 1.4–99.6, p=0.03)] compared to LRR tumors when IVRRA was performed with RT alone, but there were no associations between IVRRA and PFS or OS when cisplatin was added to the IVRRA. Conclusions IVRRA (RT alone) results correlated with PFS and OS in this prospective trial, but follow-up trials are indicated to address feasibility and to confirm results in an expanded cohort. If confirmed, IVRRA could potentially direct molecular identification