UK PubMed Central (United Kingdom)

The issue of beam-induced damage on diffractive hard X-ray optics is addressed. For this purpose a systematic study on the radiation damage induced by a high-power X-ray beam is carried out in both...Full Text Available

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International Nuclear Information System (INIS)

EXAFS measurements are useful in determining the local atomic environment of a particular element in a solid. Since there has been some controversy about the nature of the defects produced in A-15 materials by radiation damage, such studies were carried out on some A-15 compounds, V_3Ga which was damaged by neutrons, as well as Nb_3Ge damaged by 2.5 MeV a particles. In the V_3Ga sample, site exchange disorder seems to be the most important result of the neutron damage with less than 20% of the vanadium atoms on wrong sites. However, in the Nb_3Ge samples in addition to site exchange disorder, an unusual splitting of the first near-neighbor distance between the Ge and Nb is found. This splitting, approximately 0.2 A, may explain the large Debye Waller factors observed by Burbank et al.

International Nuclear Information System (INIS)

Results on defect structure study and degree of molybdenum radiation hardening irradiated by fission neutrons and medium energy alpha-particles are presented. It is shown that molybdenum irradiation by alpha-particles and neutrons leads to different degree of material hardening for the same damage level. It is established that molybdenum radiation hardening is mainly defined by radiation defect clusters visible in electron microscope whose coefficient of rigidity depends on their size. 5 refs.; 6 figs.; 2 tabs. (author).

International Nuclear Information System (INIS)

We have performed molecular dynamics simulations of radiation damage in fused silica. In this study, we discuss the role of successive cascade overlap on the saturation and self-healing of oxygen vacancy defects in the amorphous fused silica network. Furthermore, we present findings on the topological changes in fused silica due to repeated energetic recoil atoms. These topological network modifications consistent with experimental Raman spectroscopic observation on neutron and ion irradiated fused silica are indicators of permanent densification that has also been observed experimentally.

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Short communication. 5 refs., 2 figs.

International Nuclear Information System (INIS)

Shadow effect was used for investigating damage of uranium dioxide monocrystal. The dependence of shadow minimum parameters on fluence of "2"2Ne ions with 172 MeV energy was followed when detecting fission fragments. Ion dose responsible for sufficient microdamage of lattice structure, included into the classification of heavy ion damage effect on monocrystals was determined. The problem of radiation intensity effect on the character of occurred damages was studied. It was established that macroscopic sample failure, caused by generation of considerable mechanical stresses in monocrystal under beam effect could be observed along with microdamages of lattice structure at ion flux density >10"1"2 cm"-"2Xs"-"1.

International Nuclear Information System (INIS)

Channeling effect measurements have been employed to investigate radiation damage produced by 100-keV Ar ions in preferred oriented polycrystalline metal-silicide layers, such as Pd_2Si and NiSi_2 layers formed on single-crystalline Si. For room-temperature implantation, an amount of the damage in Pd_2Si layers was found to saturate at doses between 3 x 10"1"4 and 1 x 10"1"7 ions/cm"2, where the minimum aligned yield of 1.5-MeV He ions was nearly 40% of the random one. On the contrary, it was observed that the NiSi_2 layers became amorphous at doses higher than 3 x 10"1"5 ions/cm"2. These results were confirmed by the reflection electron diffraction analyses.

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The overall objective of this project has been to develop immunochemical methods to quantitate unique DNA base damages in order to facilitate studies on radiation-induced damage production and repair. Specifically, we have been using antibodies raised to damaged bases to quantitate unique lesions in model systems in order to evaluate their potential biological consequences. Our approach has been to synthesize modified nucleotides or nucleosides, conjugate them to protein carriers, and use the conjugates as immunogens in rabbits or to prepare monoclonal antibodies. We have been studying damages that are stable radiolysis products found in X-irradiated DNA and thus of potential biological consequence. Our aim is to build an in vitro and in vivo data base on the interactions between model DNA lesions and such cellular enzymes as DNA polymerases ...

International Nuclear Information System (INIS)

This text-book (electronic book - multi-media CD-ROM) constitutes a course-book - author's collection of lectures. It consists of 13 lectures in which the reader acquaints with the basis of radiobiology: Introduction to radiobiology; Physical fundamentals of radiobiology; Radiation of cells; Modification of radiation damage of cells; Reparation of radiation damage of cells; Radiation syndromes and their modification; Radiation injury; Radiation damage of tissues; Effect of radiation on embryo and fetus; Biological effects of incorporated radionuclides; Therapy of acute irradiation sickness; Delayed consequences of irradiation; Radiation oncology and radiotherapy. This course-book may be interesting for students, post-graduate students of chemistry, biology, ...

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The objectives of the research in the field of epidemiology , performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality and morbidity in nuclear workers in Belgium; (2) to document the feasibility of retrospective cohort studies in Belgium; (3) to participate in the IARC study. For radiobiology, the main objectives are: (1) to elucidate the mechanisms of the effects of ionizing radiation on the mammalian embryo during the early phase of its development, (2) to assess the genetic risks of maternal exposure to ionizing radiation, (3) to elucidate the mechanisms by which damage to the brain and mental retardation are caused in man after prenatal irradiation. The main achievements in these domains for 1997 are presented.

International Nuclear Information System (INIS)

This report briefly describes the studies on the mechanism of in vivo DNA repairing by the author in Research Reactor Institute, Kyoto Univ. for the past 30 years. First, the ability of UV radiation to induce transformation was investigated with viral DNA. The formation of thymine-thymine dimer was found harmful to organisms and such dimers were removable by UV-radiation at a low frequency. The mutability was determined in three different E.coli strains with mutator gene, mutT, mutS or mutL. The ability to excise 8-oxoguanin developed in primer DNA was deficient in mutT and miss-pairing left after DNA replication could not be recovered in mutL and mutS strains. Further, DNA repairing mechanism was investigated in other microorganisms; single-strand cleavage caused by exposure to BNCB radiation (boron-neutron-captured beam) could not be repaired in E. coli. Whereas for Deinococcus radiodurans, of which ...

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Thermoluminescence (TL) properties of sphene and epidote are of interest in studies related to their radiation damage. Natural and artificially induced TL of these minerals has, therefore, been investigated. Both minerals exhibit complex glow curves with several overlapping peaks. The Tsub(m) -Tsub(STOP) thermal cleaning procedure has revealed three peaks in the ..gamma.. ray induced glow curve of each mineral. That these peaks obey second order kinetics was indicated by the continuously slanting structure of the Tsub(m)-Tsub(STOP) curve. The TL parameters E and s have been calculated using (i) the initial rise method, and (ii) the glow-peak shape method. In general, the values of E calculated by the first method are found to be higher than those from the second. The TL curve-fitting method is also applied in order to calculate these parameters and to serve as a cross-check on the results.

UK PubMed Central (United Kingdom)

A compensatory response, viz. in vivo recovery from radiation damage to mitochondria, occurs in preclimacteric pear fruits (Pyrus communis L.) treated with ionizing...Full Text Available

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The fully depleted pn-junction charge coupled device (pn-CCD) has been developed as a detector for X-ray imaging and high-resolution spectroscopy for the X-ray satellite missions XMM and ABRIXAS. If the detector is exposed to a particle radiation environment, the energy resolution is degraded due to charge transfer losses and a dark current increase. In a first experiment, prototype devices were irradiated with 10 MeV protons. After completion of the detector development, the proton irradiation was repeated for a quantitative study of the radiation damage, relevant for the satellite missions. The irradiation test was extended by a 5.5 MeV {alpha}-particle and a 6 keV X-ray exposure of the pn-CCD, including the CAMEX preamplifier chip.

International Nuclear Information System (INIS)

Full text: It is known that the ion implantation of germanium single crystals at room temperature results in drastic alteration of the germanium surface and the formation of cellular relief. Voids were found into the near-surface damage layer. The intersection of these voids with the germanium surface, as result of sputter etching, forms cellular relief. However, exact mechanism responsible for formation of the voids is not known. A 10 and 30 keV Ga"+ irradiation of Ge #left brace#100#right brace# crystal at room temperature was carried out using a focused ion beam (FIB) system with a dose in the range 0.5x10"1"2 to 1.5x10"1"4 ion/cm"2. The topology of the modified germanium surface and the structure of the radiation damage was studied using imaging facilities of the FIB systems and transmission electron microscopy. The strong cellular structure of Ge was observed after an ion dose of 3x10"1"3 ion/cm"2. ...

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We irradiated proton beams on the ears of rabbits and the Harding-Passey mouse melanoma and observed their morphological change. We used 52 MeV proton beams from the INS-FM cyclotron. We adjusted the energy of the proton beams to be at the plateau part of the Bragg curve, at the half-way point of the Bragg peak, and at the Bragg peak. The amount of radiation was 5000rad in each case. The Harding-Passey mouse melanoma was transplanted into the subcutan of a three week old mouse. In this experiment, we used tumors, the diameter of which grew up to 1.5-2cm in 2-3 weeks after the transplantation. Using the jroscope, we observed both lightly and severely damaged cells. Using proton irradiation with the Bragg peak located at depth of 1mm in the rabbit's ears, we studied the change in the tissue. Irradiated epidermis fell off and was eroded because of radiation damage, but the ...

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Recent research findings of epidemiologist Alice Stewart suggest that nuclear workers may be at risk of contracting cancer even though their measured occupational doses fall within current safety standards. It is argued that these standards are inappropriate as they are based on extrapolations of studies on survivors of the Hiroshima and Nagasaki explosions. These individuals received single doses of radiation, whereas today's nuclear industry personnel are exposed to low-level ionizing radiation over the length of their working lives. Stewart's team linked low dose occupational exposure to ionizing radiation with an increased risk of cancer in respiratory, digestive and blood-forming tissues. The nuclear industry and United States government agencies hotly contest these assertion with their potentially damaging political and economic consequences. (UK).

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Austenitic 316LN alloy was ion-irradiated using the unique Triple Ion Beam Facility (TIF) at ORNL to investigate radiation damage effects relevant to spallation neutron sources. The TIF was used to simulate significant features of GeV proton irradiation effects in spallation neutron source target materials by producing displacement damage while simultaneously injecting helium and hydrogen at appropriately high gas/dpa ratios. Irradiations were carried out at 80, 200, and 350 C using 3.5 MeV Fe{sup ++}, 360 keV He{sup +}, and 180 keV H{sup +} to accumulate 50 dpa by Fe, 10,000 appm of He, and 50,000 appm of H. Irradiations were also carried out at 200 C in single and dual ion beam modes. The specific ion energies were chosen to maximize the damage and the gas accumulation at a depth of {approximately} 1 {micro}m. Variations in microstructure and hardness of irradiated specimens were ...

International Nuclear Information System (INIS)

In future collider experiments, where a background radiation level is estimated to be very high, e.g. around 10"2 #approx# 10"5 Gy/yr and 10"1"1 #approx# 10"1"4 n/cm"2/yr at SSC, the detectors operating around the collision point in the experiments will encounter a considerable amount of radiation. Therefore, the detectors, especially the calorimeter, are required to be resistive against high radiation levels. From this point of view, it is of great importance to study the effects of radiation damage on the performance of the detectors. The authors report preliminary results of measurements of radiation hardness of the plastic scintillating fiber Kuraray SCSF-81 against irradiation with fast neutrons and "6"0Co #gamma#-rays in the region of the neutron fluence from 1 x 10"1"1 to 5 x 10"1"3 n/cm"2 and the integrated #gamma#-ray dose from 890 ...

International Nuclear Information System (INIS)

The transmutation of minor actinides in-reactor is one solution currently being studied for the long time management of nuclear waste. In the heterogeneous concept the radionuclides are incorporating in an inert ceramic matrix. The support material must be insensitive to radiation damage. Fission product damage is the main radiation damage source during the transmutation process and therefore it is of the utmost importance to study their effects. We irradiated spinels MgAl_2O_4 (matrix of reference) and ZnAl_2O_4 by fast ions (by example: (86)Kr of approximately 400 MeV) simulating the fission products. Under these conditions, the damage is primarily due to the electronic energy losses (Se). One of the structural features of spinel AB_2O_4 is that the two cations (A(2+) and B(3+)) can exchange their site. This phenomenon ...

International Nuclear Information System (INIS)

Radiation damage studies have been carried out on undoped and CrO_4"2"- doped potassium and ammonium alums. The optical absorption bands observed around 27100 and 36500 cm"-"1 before irradiation have been attributed to the transitions t_1 #-># e and t_1 #-># t_2, on the basis of Ball-hausen and Liehr scheme. On prolonged X-irradiation, these bands disappear in both the alums and three new bands seem to grow in ammonium alum while only two new bands could be seen in potassium alum. EPR studies at RT reveal that there are two lines at g = 2.004 and g = 2.010 in ammonium alum and only one line at g = 2.004 in potassium alum. Besides these two nearly isotropic lines, there is a set of lines around g = 1.95 in both the alums. Correlating the optical and EPR studies it is concluded that SO_3"- and O_3"- centres have formed on X-irradiation in ammonium alum while only SO_3"- seems to ...

International Nuclear Information System (INIS)

Studies have linked cell phone radiation to health problems such as headaches, high blood pressure, cancer and more. There is a latency period for most diseases and it may take years and more studies before the required weight of evidence is established. But the effects are cumulative and precautions should be taken now before it is too late. The aim of the present study was to investigate if supplementation with antioxidants would protect heart and liver tissues from harmful radiation emitted by cell phone. Thirty two male albino rats were randomly divided into four equal groups: I- Control, II- Antioxidants treated group, III- 950 MHz EMR, IV- 950 MHz EMR + antioxidants. A 950 MHz EMR radiation (217-Hz pulse rate, 2-W maximum peak power, SAR Specific Absorption Rate"1.6 W/Kg) was applied to groups III and IV 60 min/day, for 30 days using an experimental ...

KoreaScience (Korea)

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International Nuclear Information System (INIS)

A study was made into microstructure and hardening in austenitic stainless steel 0Kh18N10T irradiated with neon ions (230 MeV) and neutrons (E_n > 0.1 MeV). The experiments were accomplished using an external beam of U-400 cyclotron (Dubna) and EWA reactor (Poland). The dependences of tensile properties, hardening index, microstructure, dislocation density on damaging dose were determined. An attempt is made to reveal the correlation between an yield strength increment and defect cluster accumulation. The interpretation of variations of mechanical properties and microstructure under irradiation is given.

International Nuclear Information System (INIS)

Leachability of neutron irradiated fly ash is investigated as a method for studying element leaching properties of this material with various leaching media. Quantitative aspects of radiation damage are shown to be minor. Therefore, the technique should be applicable for this purpose. It is further shown that this technique affords significant advantages over the conventional post-leaching analysis with respect to utilization of natural solutions for the investigation of fly ash leachability. However, for a few elements such as Pb, Bi, V, and Al, the various nuclear parameters involved invalidate applicability of the present technique.

International Nuclear Information System (INIS)

It has recently been found that many buildings in Taiwan were constructed with radioactively contaminated rebar, which raised great concern among the residents as well as governmental officials. In order to investigate the possible cytogenetic damage to the residents of contaminated buildings, a G-banding method was carried out on the lymphocytes of 30 radiation-exposed individuals from four families and one office building, as well as 15 control individuals from laboratory personnel. The estimated cumulative radiation doses for the exposed people range from 19.63 to 280.50 mSv. Altogether, 13 females and 17 males belonging to the radiation-exposed group, and 7 females and 8 males in the control group, were included in this study. With the exception of one sample, at least 500 metaphase spreads were scored and analyzed for each individual. All the recognizable structural aberrations ...

International Nuclear Information System (INIS)

Full text: An adaptive response is a decreased biological effect induced by a priming radiation dose given prior to a challenge dose. Adaptive responses contradict the linear-nothreshold model of risk estimation. The pKZ1 mouse chromosomal inversion assay is an extremely sensitive assay for studying the mutagenic effect of low dose radiation. A non-linear dose response for chromosomal inversion has been observed in pKZ1 spleen and prostate after a single whole body irradiation with doses between 1?Gy and 10mGy. Doses between 5-10?Gy resulted in an induction in inversions and doses between 1-10mGy resulted in a reduction below endogenous inversion frequency. These results suggest that doses in the 1-10 mGy range cause host responses which overcompensate by not only preventing inversions that would normally occur as a result of the low doses of radiation but also by preventing some of the endogenous ...

International Nuclear Information System (INIS)

A brief description of the physical process of dose enhancement effects produced by X-ray radiation on materials is given, with emphasis on the influence on electronic devices. The damages caused by X-ray radiation dose enhancement is more serious than that of #gamma#-ray with higher energy.

International Nuclear Information System (INIS)

From the frequency of diagnostic radiologic examinations and their radiation dose delivered to the population the risk of cancer induction and genetic damage is calculated on the basis of the risk factors given by the ICRP. Thus 0.38 % and 3 % of the total mortality for cancer and leukemia, resp., can be attributed to X-ray diagnostics. Chest examinations alone result in 0.07-0.7 damages per 100,000 persons depending on the imaging technique applied. (author).

International Nuclear Information System (INIS)

Electron beams as a source of directed energy are under study at the Lawrence Livermore National Laboratory (LLNL). An intense 10-kA, 50-MeV, 50-ns full-width half-maximum, pulsed electron beam is generated by the prototype Advanced Test Accelerator (ATA) at the Laboratory's Site 300. Whenever the electron beam is stopped in materials, intense radiation is generated. Estimates based on available data in the literature show that for materials such as lead, photon radiation (x ray, gamma, bremsstrahlung) levels can be as large as 10"4 roentgens per pulse at 1 m in the zero-degree direction (i.e., the electron-beam direction). Neutrons, which are emitted isotropically, are produced at a level of 10"1"3 n/m"2 per pulse. Depending upon the number of pulses and the shielding geometry, the accumulated dose is potentially lethal to personnel and potentially damaging to instrumentation that may be used for ...

International Nuclear Information System (INIS)

In view of the anticipated increased use of atomic energy in industry, the possible long-term effects of chronic radiation exposure were studied in five generations of rats. Female rats (F_0) were given tritiated drinking water ("3HOH;3#mu#Ci/ml) from adolescence (60 days) until and throughout pregnancy. A separate study showed that the maximum radioactivity in the urine is reached in 30 days, and in the blood in 42 days. In the newborns, the highest specific activity was in the nucleic acid fraction, but total radioactivity was mainly due to the water (body fluids) compartment. No signs of radiation illness or increase in cataract formation in the mothers were observed. The food and water intake and body weight changes before pregnancy were normal. The course and the outcome of pregnancy were also normal. However, 60% of the newborns (F_1) exhibited hematomas, edemas, and subdural hemorrhages, which ...

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Full text of publication follows: Li{sub 2}TiO{sub 3} is regarded as one of the most suitable candidates for the solid tritium breeder material of D-T fusion reactors. It is known that, in an operating fusion reactor, the radiation damage in Li{sub 2}TiO{sub 3} will be caused by fast neutrons, energetic tritons and helium ions generated in {sup 6}Li(n,{alpha}){sup 3}H reaction. The irradiation damage caused by such radiation may result in the microstructural changes, and the changes may affect the characteristics of Li{sub 2}TiO{sub 3} such as tritium release behavior. Thus the study of irradiation defects and microstructural changes caused by irradiation in Li{sub 2}TiO{sub 3} is essential to evaluate its irradiation performance. Simulation of the fusion reactor environment and hence the study of a synergistic effect of atomic displacement ...

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The research carried out in Canada in the design of containers for the disposal of radioactive waste has focussed on spent nuclear fuel, even though the quantities of other currently stored radioactive wastes are substantially greater. Research carried out at the Royal Military College of Canada on the effects of mixed fields of radiation on high polymer adhesives and composite materials has shown that some polymers are quite resistant to radiation and could well serve in the fabrication of radioactive waste disposal containers. The purpose of this research was to determine if thermoplastic polymers could be used as superior materials to replace metals in the application of low and intermediate level radioactive waste disposal containers. Polymers have the advantage that they do not corrode like metals. The experimental methods, used in this research, focused on the effects of radiation on the properties of the materials. ...

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The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the only major protection to astronauts from harmful exposure. Unlike low-linear energy transfer (LET) {gamma} or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure, since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak. The Bragg curve does not necessarily represent the biological damage along the particle traversal, and the 'biological Bragg curve' is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Here we used a unique irradiation geometry to measure the biological response across the Bragg curve in human fibroblasts exposed to ...

Science.gov (United States)

Cancer and Tobacco Abuse

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The literature of radiation damage measurements on cadmium zinc telluride (CZT), cadmium telluride (CT), and mercuric iodide (HgI{sub 2}) is reviewed and in the case of CZT supplemented by new alpha particle data. CZT strip detectors exposed to intermediate energy (1.3 MeV) proton fluences exhibit increased interstrip leakage after 10{sup 10} p/cm{sup 2} and significant bulk leakage after 10{sup 12} p/cm{sup 2}. CZT exposed to 200 MeV protons shows a two-fold loss in energy resolution after a fluence of 5 {times} 10{sup 9} p/cm{sup 2} in thick (3 mm) planar devices but little effect in 2 mm devices. No energy resolution effects were noted from moderated fission spectrum of neutrons after fluences up to 10{sup 10} n/cm{sup 2}, although activation was evident. Exposures of CZT to 5 MeV alpha particle at fluences up to 1.5 {times} 10{sup 10} {alpha}/cm{sup 2} produced a near linear decrease in peak position with fluence and increases in FWHM ...

International Nuclear Information System (INIS)

In radiation risk assessment it must be differentiated between somatic and genetic effect on the one hand as well as between stochastic and non-stochastic effect on the other. According to definitions of the ICRP report 26 the limit for the dose equivalent of all tissues prevents non-stochastic radiation effects. With stochastic radiation effects probably exist no threshold doses; therefore the ALARA principle must be applied concerning radiation protection. The individual risk by stochastic radiation effects in its linear, linear-quadratic and quadratic extrapolations, respectively, is discussed in detail. The effective stochastic dose equivalent (H/sub eff/) as well as collective dose and collective damage are outlined.

International Nuclear Information System (INIS)

The authors summarize the significant dose-related effects on brain development which have emerged largely within the last six years of study of prenatally exposed A-bomb survivors. The results are described primarily in terms of the DS86 estimates and differences between these and the older T65DR dose estimates are discussed. The severe mental retardation sample was based on 1598 individuals taken from the PE-86 sample, and the intelligence test scores considered from the same sample involved 1673 children. The authors also discuss some of the recent neurobiological developments that appear relevant to an understanding of the biological bases of dose-related events observed, and suggest future research that may contribute either to further delineation of exposure consequences or to the explanation of the cellular and molecular origins of observed effects. (UK).

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The results of nine years of study of the 237 patients who suffered from acute radiation syndrome (ARS) as a consequence of the Chernobyl accident are reported. Thirty-eight of these patients have died, 28 in the acute period in 1986, 5 in 1987-90 and 5 in 1992-93. The reasons for death show no clear tendencies. They include: gangrene of the lung, organic disease of the brain and spinal chord, hypoplasia of haematopoeisis, coronary heart disease, sarcoma and an automobile accident. Investigations have been carried out on an annual obligatory basis of the patients` haemopoietic, immune, nervous and endocrine systems. An analysis of the data is presented. Histograms are included showing the incidence of digestive tract, nervous system, respiratory and cardiovascular disorders, the frequency and degree of disablement and serum prolactin concentration. The types of skin damage sustained by 39 of the patients are listed. (6 ...

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This book contains over 20 selections. Some of the titles are: Continuum damage mechanics studies on the dynamic fracture of concrete; Dynamic compressive strength of cementitious materials; Rate-sensitivity of mode I and mode II fracture concrete; and An impact damage model of concrete.

Science.gov (United States)

Thin film solar cells and solar cell testing - photovoltaic cells, radiation damage to cadmium sulfide solar cells, and airplane testing of solar cells

UK PubMed Central (United Kingdom)

BackgroundDNA repair is the general term for the collection of critical mechanisms which repair many forms of DNA damage such as methylation or ionizing radiation. DNA repair has...Full Text Available

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Systematics of neutron capture radiative width were studied in the target element range from Th to Cm. Reduced radiative widths were analyzed with a simple radiative width formula based on E1 transition. Average radiative width is presented with the standard deviation of 15%. (author)

International Nuclear Information System (INIS)

The case of spontaneous radiation of channeled ultrarelativistic particles is considered when the dipolarity condition is not satisfied. The change of the particle longitudinal velocity affecting the maximum radiation frequency is included. The angular and frequency characteristics of the radiation for superhigh energies are studied for the first time. It is shown that there is an optimum energy at which the radiation density is maximum. The influence of the angle at which electrons enter a crystal and of the beam divergence on the radiation is investigated. The problem of quasichanneled particle radiation and also the radiation in axis-plane transitions are considered. (author).

International Nuclear Information System (INIS)

Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials ...

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Cell death in general can be a physiological process of cell number regulation in tissue, or it can be the result of exo or endogenous injuries, such a low-dose of radiation. Chicken B cell population in the bursa of Fabricius are very susceptible to PCD. Our present studies concern the development of radiation damage of chicken defence mechanisms. In 6 experiments pathogen free chicken were irradiated by gamma rays with the total doses of 0.25, 0.5, 1.0, 2.0 and 4.0 Gy. The induction of apoptosis was checked by Flow-cyto-meter 12 h after irradiation in bursa cell suspension. There is some increase in the number of induced apoptotic cells 12 h after irradiation at the dose 0.5-.4.0 Gy. There were no significant changes in the proportion of proliferating lymphocytes (G2 M), but cellularity decreased significantly at dose 2.0 and 4.0 Gy/12 h after irradiation. (author)

International Nuclear Information System (INIS)

Perforated thermoplastic masks are used to provide patients immobilization. This procedure inserts a material in the path of the radiation beam, that attenuates and modifies the beam fluence and flatness. The present study evaluates the increase in skin dose as a result of using thermoplastic masks. Relative doses were measured on the surface of a solid water phantom, in the presence and absence of masks. These masks were stretched according to deformation patterns observed in clinical routine. The measurements were obtained with a plane-parallel chamber (Markus type 23343) and radiochromic film (EBT Gafchromic) for 6MV X-rays from a linear accelerator, and for a radiation beam from a cobalt therapy unit. The results showed that thermoplastic masks, whose thickness varied between 2 and 3 mm, increased the dose on the surface by a factor of 3. Due to the variations in the skin dose distribution, clinical procedures were ...

International Nuclear Information System (INIS)

An attempt was made to quantify the radiation risk of diagnostic radiology. After a general introduction of terms as radiation damage, radiation risk and effective dose equivalent, based on publications of the ICRP, somatic dose indexes were computed for several radiologic investigations, that comprise organ doses committed to red bone marrow, lung, female breast and thyroid with and without considering the rest of the body. The dose for the rest of the body was assumed to be equal to the dose received by the red bone marrow, that is also distributed over the whole body. Neglecting the exposure of the rest of the body resulted in an insignificant increase in the estimated somatic risk, with its experimental determination not being necessary. (author).

International Nuclear Information System (INIS)

... chemical radiation effects decomposition extraction columns gamma radiation

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The topics of these short lectures on the subject of cyclic stress were: Microstructural mechanisms of damage accumulation under a multistage cyclic stress until incipient cracking; influence of surface decarbonizing phenomena on the failure behaviour of steel construction parts subjected to cyclic stress; thermocyclic fatigue of pipe samples of austenitic steel 1.4436; studies on surface structuring, microstructure and fatigue in LCF area. The short lectures on effects of quasi-static and creep stress were: Shear fracture in AlMg alloys as a result of local plastic instability; study of formation and growth of pores for an early recognition of damage and the course of damage in heat-resistant steels under creep test; experimental and numeric studies of the infuence of the microstructure on the course of damage during shear fractures of ...

International Nuclear Information System (INIS)

Displacements per atom (DPA) is a widely used damage unit for displacement damage in nuclear materials. Calculating the DPA for SiC irradiated in a particular facility requires a knowledge of the neutron spectrum as well as specific information about displacement damage in that material. In recent years significant improvements in displacement damage information for SiC have been generated, especially the energy required to displace an atom in an irradiation event and the models used to describe electronic and nuclear stopping. Using this information, numerical solutions for the displacement functions in SiC have been determined from coupled integro-differential equations for displacements in polyatomic materials and applied in calculations of spectral-averaged displacement cross sections for SiC. This procedure has been used to generate spectrally averaged displacement cross sections for SiC in a ...

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Numerical simulation of dynamic fracture of concrete slabs, impacted by steel projectiles, was carried out in this study. The concrete response was described by a continuum damage model. This continuum damage model was originally developed to study rock fragmentation and was modified in the present study with an emphasis on the post-limit structural response. The model was implemented into a transient dynamic explicit finite element code LS-DYNA2D and the code was then used for the numerical simulations. The specific impact configuration of this study follows the experiment series conducted by Hanchak et al. Comparisons between calculated results and measured data were made. Good agreements were found.

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The phenomena and effects of airblast, ground shock, thermal radiation, cratering and ejecta, and debris cloud and deposition from the eruption of Mt. St. Helens were compared to those that would result from a nuclear explosion to determine if phenomena or effects were analogous and thus might provide useful data for military nuclear weapon effects studies. It is concluded that the phenomena are not analogous. In particular, airblast destruction was caused by clouds of ash driven by subsonic winds, rather than by a supersonic shock wave that would be the damage mechanism of a nuclear explosion. Because of the lack of analogy between the eruption and nuclear explosion phenomena, it appears questionable that any of the effects are analogous; therefore, it is unlikely that anything more of military interest can be gained from studying the effects of the eruption. However, key contacts for further ...

Energy Technology Data Exchange (ETDEWEB)

The structural variations of amorphous metals, such as Pd/sub 80/Si/sub 20/, with irradiation of helium ion, neutron, and gamma ray have been mainly pursued by the method of X-ray diffraction and thermal analysis. It should be noticed that the amorphous metals show a radiation resistance, that is, no remarkable structural changes under helium ion, neutron, and gamma ray irradiation.

International Nuclear Information System (INIS)

Post-irradiation annealing was used to help identify the role of radiation-induced segregation (RIS) in irradiation-assisted stress corrosion cracking (IASCC) by preferentially removing dislocation loop damage from proton-irradiated austenitic stainless steels while leaving the RIS of major and minor alloying elements largely unchanged. The goal of this study is to better understand the underlying mechanisms of IASCC. Simulations of post-irradiation annealing of RIS and dislocation loop microstructure predicted that dislocation loops would be removed preferentially over RIS due to both thermodynamic and kinetic considerations. To verify the simulation predictions, a series of post-irradiation annealing experiments were performed. Both a high purity 304L (HP-304L) and a commercial purity 304 (CP-304) stainless steel alloy were irradiated with 3.2 MeV protons at 360 deg. C to doses of 1.0 and 2.5 dpa. Following irradiation, ...

International Nuclear Information System (INIS)

Initial rates of resistivity-measured low-temperature damage production by fission-spectrum fast neutrons have been determined for 14 metals in the same very well characterized irradiation facility. Six of these metals were fcc, 5 bcc, and 3 hcp. Most were of quite high purity. Observed damage rates, after correction for all known extraneous resistivity-producing effects, were compared with rates predicted by the damage calculation code RECOIL, using parameters chosen from the literature. These parameters, effective displacement threshold energy, E/sub d/, and Frenkel-pair resistivity, rho/sub F/, were in many cases only best estimates, the further refinement of which may be aided by the present results. Damage efficiencies (measured/predicted rates) follow the same trends by crystal classes as seen in other fast-neutron studies.

Energy Technology Data Exchange (ETDEWEB)

This short survey focuses on the main radiation-induced base lesions that have been identified within cellular DNA. For this purpose, sensitive assays that are aimed at measuring a few modifications per 10{sup 7} normal bases were set-up. In that respect high performance liquid chromatography - tandem mass spectrometry (CLHP-MS/MS) was found to be able to single out the formation of 9 oxidized nucleosides and two modified nucleo-bases out of the 70 oxidative base lesions that have been identified in model systems. As a striking result, it was found that in the DNA of {gamma}-irradiated human monocytes, the formamide-pyrimidine derivative of guanine is produced in a higher yield than the ubiquitous 8-oxo-7,8-dihydro-guanine damage, both arising from the same radical precursor. However, relatively high doses of ionizing radiation (> 20 Gy) have to be applied in order to detect an increase in the level of the ...

International Nuclear Information System (INIS)

Titanium base 'alpha'-alloys (Pt-7M, RK-20 and Ti-5Al-2Zr-1.5V) are considered for their behaviour under neutron irradiation. The role of alloying elements in radiation hardening is discussed depending of neutron fluence and irradiation temperature. For PK-20 alloy three stages of change in mechanical properties are revealed which are following: incubation period and weak hardening, intense radiation hardening, radiation hardening attenuation. Irradiation temperature rise results in an increase of incubation period and threshold neutron fluence. A special attention is paid to hydrogen absorption in #alpha#-titanium alloys under irradiation. It is concluded that titanium base 'alpha'-alloys are serviceable as structural materials in nuclear plants with allowance made for peculiar features of their radiation behaviour. 4 refs.; 7 figs.; 1 tab.

DEFF Research Database (Denmark)

Functional magnetic resonance imaging (fMRI) in young children may provide information about the development of the visual cortex, and may have predictive value for later visual performance. The purpose of this study was to evaluate the usefulness of fMRI for examining cerebral processing of vision in very young infants and in infants with brain damage. We examined 15 preterm infants, 12 children suspected of having a cerebral visual impairment and 10 children with a normal visual system, all of whom were either spontaneously asleep or sedated with chloral hydrate. Cortical response to stroboscopic light stimulation could be demonstrated in all technically acceptable data sets from children with a post-menstrual age (PMA) of > 41 weeks, but not in younger infants. Children < 60 weeks PMA showed either a blood oxygenation level-dependent (BOLD) signal increase or decrease, while all older children showed a signal decrease. The activated ...

Science.gov (United States)

A new type of radiation which occurs when particles are accelerated in the field of a longitudinal wave and in a transverse magnetic field is studied. The characteristics of such spontaneous radiation are obtained, and the influence of collective effects on the radiation is analyzed. The application of the findings to the theory of free electron lasers is discussed. 8 references.

International Nuclear Information System (INIS)

Kinetic Monte Carlo (KMC) computer simulations are performed to determine the kinetics of SIA cluster 'clouds' in the vicinity of edge dislocations. The simulations include elastic interactions amongst SIA clusters, and between clusters and dislocations. Results of KMC simulations that describe the formation of 'SIA clouds' during neutron irradiation of bcc Fe and the corresponding evolution kinetics are presented, and the size and spatial distribution of SIA clusters in the cloud region are studied for a variety of neutron displacement damage dose levels. We then investigate the collective spatio-temporal dynamics of SIA clusters in the presence of internal elastic fields generated by static and mobile dislocations. The main features of the investigations are: (1) determination of the kinetics and spatial extent of defect clouds near static dislocations; (2) assessment of the influence of localized patches of SIA clouds on the ...

International Nuclear Information System (INIS)

Studies were made on different types of packaging materials used for packing dried fish in the Philippines with a view to finding a suitable packaging material for irradiated dried fish. Among these packaging materials (polyethylene, cello/polyethylene, polyester/polyethylene, Kraft paper, polypropylene and interwoven polypropylene sacks), polyester/polyethylene laminate was the most resistant material against penetration by Dermestes carnivorous. No insect damage occurred on the dried fish packed in interwoven polypropylene lined with polyester/polyethylene laminate. The cost per sack of such packaging material having a capacity of 50-80 kg is US$ 0.50. The sack lined with polyester/polyethylene proved to be durable for surface transportation from Bacolod City to Manila (approx. 360 miles). Radiation treatment at 225 krad was effective against bacterial contamination but not effective in inhibiting mould growth. Raw fish ...

Energy Technology Data Exchange (ETDEWEB)

Data are presented to support the hypothesis that the initial step in the morphologic transformation of irradiated rodent (BALB/3T3) cells is a frequent cellular event involving a large fraction of the irradiated population. This process appears to involve DNA damage, but not to represent a targeted mutation in specific structural gene(s). Morphologic transformation and immortalization appear to be distinct steps in the overall process of transformation. In contradistinction to rodent cells, immortalization is a very rare event in human diploid cells which is induced at extremely low frequencies. The hypothesis is presented that immortality develops among clones of cells bearing stable chromosomal rearrangements which emerge during the proliferation of a population of radiation damaged cells.

Energy Technology Data Exchange (ETDEWEB)

In acute intoxication, uranium (U) not only inhibits bone formation but its excretion in urine also causes renal damage. The former effect is ameliorated by tetracycline (TC), probably due to its chelation property, which might also prevent U deposition in bone. Chemical determination of U incorporated in bone and a histological study of the kidneys were performed on animals injected with U and then treated with TC. The results showed that TC was unable to prevent the binding of U to bone while it exacerbated U-induced renal damage.

International Nuclear Information System (INIS)

This paper describes examples of the damage resulting from the impact of a whipping pipe on a nearby pressurised pipe. The work is a by-product of a study of the motion of a whipping pipe. The tests were conducted with small-diameter pipes mounted in rigid supports and hence the results are not directly applicable to large-scale plant applications where flexible support mountings are employed. The results illustrate the influence of whipping pipe energy, impact position and support type on the damage sustained by the target pipe. (author).

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

The radiation-induced microstructural changes have been studied by cross-sectional transmission electron microscopy for single-crystal {alpha}-Al{sub 2}O{sub 3} samples irradiated with triple ion beams (0.25 MeV H{sup +}, 0.6 MeV He{sup +} and 2.4 MeV O{sup 2+}; `Triple (A)`), (0.33 MeV H{sup +}, 0.45 MeV He{sup +} and 1.3 MeV O{sup +}; `Triple (B)`) and three consecutive single ion beams (0.3 MeV H{sup +} ion followed by 0.6 MeV He{sup +} and then 0.8 MeV O{sup +} ions) at 650 C to doses in the range 0.1-8.4 dpa at the damage peak. In the specimen irradiated with Triple (A), having the same average projected range to a total peak dose of 3.7 dpa, cavities with an average diameter of 13 nm were formed between 1.2 and 1.75 {mu}m in depth causing a swelling of 0.1% at the peak, which is larger than those of the specimens irradiated with other conditions. The extent of the cavity-introduced region is some 40% smaller than ...

International Nuclear Information System (INIS)

The point at which the common final pathway for induction of cancer by chemical carcinogens and ionizing radiation has not been identified. Although common molecular targets are suggested by recent findings about the role of oncogenes, the mechanism by which the deposition of radiation energy and the formation of adducts or other DNA lesions induced by chemicals affects the changes in the relevant targets may be quite different. The damage to DNA that plays no part in the transformation events, but that influences the stability of the genome, and therefore, the probability of subsequent changes that influence tumorigenesis may be more readily induced by some agents than others. Similarly, the degree of cytotoxic effects that disrupt tissue integrity and increase the probability of expression of initiated cells may be dependent on the type of carcinogen. Also, evidence was presented that repair of the initial lesions could ...

Energy Technology Data Exchange (ETDEWEB)

The information given in the present report about the Chernobyl accident and its radiological consequences indicates a serious crisis of the international radiation community. The following signs of this crises can be discerned: The international radiation community did not recognize the real reasons of the accident for a long time. It could not make a correct assessment of the damage to the thyroid of the affected populations of Belarus, Russia and the Ukraine. Up to present time it rejects the reliable data on hereditary malformations. It is not able to accept reliable data on the increase in the incidence in all categories of people affected by the Chernobyl accident. The international radiation community supported the Soviet authorities in their attempts to play down the radiological consequences of the Chernobyl accident for a long time. (author)

Energy Technology Data Exchange (ETDEWEB)

The fundamental product of tetracycline hydrochlorine gamma radiolysis was separated in its solid state. From the results of spectroscopic studies it has been established that it is des-N,N-dimethylaminotetracycline.

Energy Technology Data Exchange (ETDEWEB)

To determine if barbiturates would protect brain at high doses of radiation, survival rates in rats that received whole-brain x-irradiation during pentobarbital- or lidocaine-induced anesthesia were compared with those of control animals that received no medication and of animals anesthetized with ketamine. The animals were shielded so that respiratory and digestive tissues would not be damaged by the radiation. Survival rates in rats that received whole-brain irradiation as a single 7500-rad dose under pentobarbital- or lidocaine-induced anesthesia was increased from between from 0% and 20% to between 45% and 69% over the 40 days of observation compared with the other two groups (p less than 0.007). Ketamine anesthesia provided no protection. There were no notable differential effects upon non-neural tissues, suggesting that pentobarbital afforded protection through modulation of ambient neural activity during ...

International Nuclear Information System (INIS)

Total-dose irradiation seriously damages MOS devices and their circuit performance. Threshold voltage shifts, transconductance degradation and increase in off-state leakage current are generally observed for irradiated devices. These instabilities are essentially due to positive and/or negative charge trapping in SiO_2 and interface trap generation at the SiO_2/Si interface. Radiation hardening of CMOS VLSIs is to eliminate these trapping effects, and for this purpose, special considerations for fabrication processes and layout design are necessary. In this paper, basic mechanisms for radiation-induced charge trapping and related effects on MOS devices are reviewed. Also discussed are radiation-hardening technologies from both fabrication-process and layout-design viewpoints. Using these technologies, 1 #mu#m radiation-hard CMOS gate arrays have been successfully developed. ...

International Nuclear Information System (INIS)

Nitroaromatic radiosensitizers become metabolically bound preferentially to hypoxic cells and at least 10/sup 9/ adducts/cell can be tolerated as non-toxic. EMT-6 tumor cells have been incubated in hypoxia in the presence of /sup 3/H-Misonidazole and /sup 125/I-Azomycin Riboside for various times and the amount of /sup 3/H or /sup 125/I bound/cell was determined. Cells were stored as monolayers at 25"0C for up to 96 hr to accumulate radioactive decays and transferred at various times to 37"0C for colony-forming assays. No radiation inactivation was measured in cells which had incorporated at least 10/sup 6/ /sup 3/H or 10/sup 5/ /sup 125/I atoms. Previous studies had shown that -- 1% of MISO adducts to EMT-6 cells was associated with cellular DNA. These data indicate that the radiation-induced damage produced by these quantities of bound /sup 3/H or /sup 125/I causes little or not cell inactivation. The ...

DEFF Research Database (Denmark)

The universe is full of exotic particles and waves. Some, such as neutrinos, pass through our neighbourhood unnoticed; others, such as extreme uv radiation, are absorbed by the upper atmosphere before they are able to do too much damage. For a long time, any systematic attempt to understand how our weather can be affected by extra-terrestrial sources other than solar visible and infrared radiation has been a lively and often controversial diversion from mainstream research. But recent scientific and technological breakthroughs and concern over long-term climate change have brought this subject into the spotlight.

Energy Technology Data Exchange (ETDEWEB)

Accurate calculations of atomic displacement damage in materials exposed to neutrons require detailed spectra for primary recoil nuclei. Such data are not available from direct experimental measurements. Moreover, they cannot always be computed accurately starting from evaluated nuclear data libraries such as ENDF/B-V that were developed primarily for neutron transport applications, because these libraries lack detailed energy-and-angle distributions for outgoing charged particles. Fortunately, a new generation of nuclear model codes is now available that can be used to fill in the missing spectra. One example is the preequilibrium statistical-model code GNASH. For heating and damage applications, a supplementary code called RECOIL has been developed. RECOIL uses detailed reaction data from GNASH, together with angular distributions based on Kalbach-Mann systematics to compute the energy and angle distributions of recoil nuclei. The ...

Energy Technology Data Exchange (ETDEWEB)

The overall objective of this project is to produce antibodies to unique modified DNA bases and develop immunochemical assays to quantitate these lesions in damaged DNA. During this past year we have developed an antibody and chemical test to quantitate a basic sites in DNA and produced antibodies to the 8-oxopurines. This report discusses the detection of a basic sites in DNA and the preparation of antibodies to 8-hydroxyadenine and 8-hydroxyguanine.

UK PubMed Central (United Kingdom)

Objectives To provide direct estimates of risk of cancer after protracted low doses of ionising radiation and to strengthen the scientific basis of radiation protection standards for environmental,...Full Text Available

International Nuclear Information System (INIS)

The effect of ionizing radiation (2, 5, and 10 KGy of gamma rays) on muscle ultrastructure of grass shrimps (Penaeus monodon Fabricius) tails at ambient or frozen (-18"0C) temperature was investigated by transmission electron microscopy (TEM). No significant change was found in muscle ultrastructure of shrimp meat irradiated at doses of 2 or 5 KGy and then stored at 4"0C for 0 and 8 days. However, in shrimps which were irradiated at ambient temperature at a dose of 10 KGy, the margin of A-band of the myofibrils in longitudinal sections exhibited an irregular zig-zag pattern. In cross section some myosin filaments in the A-band regions were missing. A possible interpretation of these results would be that 10 KGy gamma irradiation dose at ambient temperature depolymerized myosin in the A-band from the tail of thick filament. Actin damage was also observed in some cross sections. Irradiation damage of sarcoplasmic membranes ...

International Nuclear Information System (INIS)

In radiation processing of food, the product often has to be prepackaged to prevent microbial recontamination during and after irradiation. The packaging material is exposed to radiation during radiation processing and radiation stability is a key consideration in the selection of packaging materials. The effects of ionizing radiation on many food packaging materials at the dose levels recommended for food precessing can be minimized by selecting appropriate radiation resistant materials. It is important to select materials in which chemicals formed as a result of the radiation treatment do not migrate and interact with the food, affecting its organoleptic and toxicological aspects. It is also important to select materials in which the physical properties are not altered to the extent they cannot resist damage during ...

International Nuclear Information System (INIS)

It is shown that low-frequency elastic vibrations of near-surface planar defects cause high-frequency ultrasonic radiation in surrounding air. The frequency conversion mechanism is concerned with contact nonlinearity of the defect vibrations and provides efficient generation of air-coupled higher-order ultraharmonics, ultrasubharmonics, and combination frequencies. The nonlinear air-coupled ultrasonic emission is applied for location and high-resolution imaging of damage-induced defects in a variety of solid materials.

International Nuclear Information System (INIS)

1. It is not possible to give a threshold value for the dose - nor for genetic neither for somatic late effects. 2. The linear dose-effect exprapolation is not conservative in the sense of 'fying on the safe side'. 3. There has been found no relative reduction of the effects at chronic radiation exposure in man. 4 The numbers given by authorities and utilities for damage rates per rem received, that are called upper limits, are by far too low. (orig./HP).

International Nuclear Information System (INIS)

Correlation characteristics of quantum noise on the shadow radiation image (RI) of the object under nondestructive testing are studied. Mathematical model of RI occasional distortions is derived. The model takes into account the parameters of object under testing and of radiation beam by radiation quanta flux density. The results obtained can be used as a component in the process of investigation of various radiation testing systems

Energy Technology Data Exchange (ETDEWEB)

Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities ...

International Nuclear Information System (INIS)

A study is made of the mechanical properties of vanadium irradiated with fast neutrons up to dose 8.6.10"-"4 dpa, as a function of the temperature of post-radiation annealing. The radiation-annealing hardening (RAH) effect is observed at 300"oC, in agreement with previous studies. It is established for the first time that RAH is accompanied by fall in ductility. A phenomenological model is described which explains the dependence of RAH on radiation dose and temperature, as well as on the content of chemically active alloying impurities. (author).

International Nuclear Information System (INIS)

The two main aspects of the concept proposed by the ICRP in recommendation 26 for the radiation risk, the differentiation of stochastic and non stochastic damages and the qualification of the stochastic risk, are discussed in its consequences for radiation protection in X-ray diagnostics. Quantitative results from the literature serve to demonstrate the risk factors for the various organs and their sum concerning the position of the layer. As special points of somatic risk appeared the mamma and the pelvic region. The particular risk of CT examination is determined by number and position of the layers and the scan parameters of the system. For typical CT examination the resulting risk factors are estimated in comparison with conventional X-ray diagnostics. The somatic risk of CT examination is relatively high and comparable to conventional examination with the highest risk, while the genetic risk - as in conventional ...

CERN Document Server

Radiation damage is considered to be the major problem that still prevents imaging an individual biological molecule for structural analysis. So far, all known mapping techniques using sufficient short wave-length radiation, be it X-rays or high energy electrons, circumvent this problem by averaging over many molecules. Averaging, however, leaves conformational details uncovered. Even the anticipated use of ultra-short but extremely bright X-ray bursts of a Free Electron Laser shall afford averaging over 10^6 molecules to arrive at atomic resolution. Here we present direct experimental evidence for non-destructive imaging of individual DNA molecules. In fact, we show that DNA withstands coherent low energy electron radiation with deBroglie wavelength in the Angstrom regime despite a vast dose of 10^8 electrons/nm^2 accumulated over more than one hour.

Energy Technology Data Exchange (ETDEWEB)

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

International Nuclear Information System (INIS)

Ultra-shallow junction formation in deep submicron Si devices is limited by anomalous diffusion of the dopant, which is related to the release of interstitials from defect clusters formed during the implantation of energetic ions or the subsequent annealing. The work described in this dissertation is concerned with the effects of low energy B ion implantation, especially damage formation, clustering and its annealing. After a review of the stopping and ranges of energetic ions in Si, the formation of implant damage, in particular of point defects, their migration, agglomeration and annihilation, including the involvement of dopant ions, is considered. A description of the Salford ultra low energy implanter is given and the main analysis technique, medium ion energy scattering (MEIS) reviewed. Additional analytical techniques used, such as secondary ion mass spectrometry (SIMS), 4-point probe and cross section transmission microscopy (XTEM) as ...

Energy Technology Data Exchange (ETDEWEB)

Specimen damage and element loss induced by 3 MeV proton and 2 MeV alpha particle bombardment of thin sections of freeze-dried kidney tissue and embedding medium have been studied. Yields of ions scattered from H and C, and characteristic X-rays were measured versus accumulated charge, for curent densities in the range from 8x10{sup -15} to 1.1x10{sup -11} A/{mu}m{sup 2}. Structural damage, dissolouration and loss of S, Cl, C and H have been observed. Implications of this study for ion beam microanalysis of biological tissues are discussed with particular reference to the results for H loss. (orig.).

International Nuclear Information System (INIS)

The indium implant damage and diffusion behavior in thin silicon-on-insulator (SOI) with a 200 nm top silicon layer were studied for different implantation energies and doses. Rutherford backscattering spectrometry in the channeling mode (RBS/C) was used to characterize the implant damage before and after annealing. Secondary ion mass spectrometry (SIMS) was used to study the indium transient enhanced diffusion (TED) behavior in the top Si layer of the SOI structure. An anomalous redistribution of indium after relatively high energy (200 keV) and dose (1 x 10"1"4 cm"-"2) implantation was observed in both bulk Si and SOI substrates. However, there exist differences in these two substrates that are attributable to the more predominant out-diffusion of indium as well as the influence of the buried oxide layer in the SOI structure.

Science.gov (United States)

In order to maintain a safe operation and availability of generating facilities, qualitative and quantitative assessment of piping vibration was performed vibration sources and damages of piping support was identified on the second piping system of Wolsun...

UK PubMed Central (United Kingdom)

Chemical reactions in living cells are under strict enzyme control and conform to a tightly regulated metabolic program. However, uncontrolled and potentially deleterious endogenous reactions occur,...Full Text Available

UK PubMed Central (United Kingdom)

PurposeCataract is the leading cause of blindness and is associated with oxidative damage and protein modification in the lens. In the present study, we have employed proteomic and...Full Text Available

CERN Document Server

Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.

UK PubMed Central (United Kingdom)

The United Kingdom Atomic Energy Authority mortality study was designed to investigate the relation between exposure to ionising radiation and mortality among the authority's employees. The present...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Up to this time the sigmoid colostomy has been widely accepted and conventional treatment for radiation-injured rectum, but patients without residual malignancy strongly desire to live without colostomy. We have tried to remove the involved rectal segments by sphincter-saving procedures. Four patients underwent these procedures, pull-through procedure in three and low anterior resection in one. Among sphincter-saving procedures, pull-through procedure was most adequate. Provided the following five conditions are fulfilled, pull-through procedure should be considered for severe radiation-injured rectum. (1) No recurrence of initial malignancy in the pelvis. (2) More than 2 cm intact rectal segment above dentate line may be preserved. (3) No radiation-injured segment in upper sigmoid. (4) No severe radiation damage in small intestine. (5) Patients under 70 year-old, with normal tonus ...

International Nuclear Information System (INIS)

... radioisotopes coincidence methods energy-level transitions gamma radiation

Science.gov (United States)

... laser structure. However, still the greater part (60%) of emitted photons is a result of a spontaneous radiation process. In ...

British Library Electronic Table of Contents (United Kingdom)

A formula is obtained which describes the kinetics of low-temperature radiation hardening caused by creation of dislocation loops of interstitial type during irradiation. The radiation hardening of aluminum and vanadium is estimated using this formula and results of experiments on studying processes of nucleation and growth of interstitial dislocation loops in these materials by transparent electron microscopy. It is shown that the proposed formula is valid for description of the kinetics of low-temperature radiation hardening.

International Nuclear Information System (INIS)

The first essential before embarking on the radiation-hardening of electrical insulation - mostly magnet coils - in any beam line application is to obtain a reliable estimate of the dose to the components. These are examples ( switchyards at SLAC and LAMPF) where the degree of hardness specified was much higher than was required. Although experience shows that the cost premium for substantial radiation - hardening is of the order of 10%, it has also become clear that well - designed beam line have negligible losses: hardening is required only in the vicinity of targets, collimators or other beam - intercepting devices. Where the beam is deliberately scraped, local shielding will minimize the associated radiation in the surroundings. Electron machines have their own special problems due to synchrotron radiation, so certainly coils and other electrical equipment should be kept away from the beam bend - ...

British Library Electronic Table of Contents (United Kingdom)

Eugenol, the principal chemical component of clove oil from Eugenia aromatica has been long known for its analgesic, local anesthetic, anti-inflammatory, and antibacterial effects. The interaction of the eugenol with ten different hydrophobic and hydrophilic antibiotics was studied against five different Gram negative bacteria. The MIC of the combination was found to decrease by a factor of 5-1000 with respect to their individual MIC. This synergy is because of the membrane damaging nature of eugenol, where 1mM of its concentration is able to damage nearly 50% of the bacterial membrane. Eugenol was also able to enhance the activities of lysozyme, Triton X-100 and SDS in damaging the bacterial cell membrane. The hydrophilic antibiotics such as vancomycin and b-lactam antibiotics which have ...

International Nuclear Information System (INIS)

Scanning spreading resistance microscopy (SSRM) has been applied to study focused ion beam (FIB) induced damage in silicon in dependence on ion irradiation doses from 10"1"2 cm"-"2 to 2#centre dot#10"1"6 cm"-"2. Starting from the lowest dose, SSRM detects increasing spreading resistance (SR) with increasing dose. For doses from 2#centre dot#10"1"3 cm"-"2 to 4#centre dot#10"1"4 cm"-"2, a slight decrease of SR is measured whereas for higher doses SR again slightly increases. The results are explained by physical effects like decreased carrier mobility due to increased scattering, amorphisation of silicon and precipitation of implanted Ga ions. The results clearly prove that SSRM is well suited for the fast detection of ion beam induced damage with high lateral resolution.

Energy Technology Data Exchange (ETDEWEB)

Microstructural observations of damage around indentations in Ti{sub 3}SiC{sub 2} are presented. The Vickers hardness decreased with increasing load and asymptotically approached 4 GPa at the highest loads. No indentation cracks were observed even at loads as high as 300 N. Preliminary strength versus indentation plots indicate that, at least for the large-grained material ({approx}100 {micro}m) studied here, Ti{sub 3}SiC{sub 2} is a damage-tolerant material able to contain the extent of microdamage to a small area around the indent. The following multiple energy-absorbing mechanisms have been identified from scanning electron micrographs of areas in the vicinity of the indentation: diffuse microcracking, delamination, crack deflection, grain push-out, grain pull-out, and the buckling of individual grains.

International Nuclear Information System (INIS)

High quality "3"1P MR spectra (signal to noise ratio (S/N) approximately 18, 15 min acquisition for each spectrum) were consistently obtained with surface coils over a period of 6-week RT. Both transient and steady state alterations in metabolites in response to RT were found in this case. The transient changes occurred during the first 3 hr immediately after the 3rd fractionated RT, these changes include the transient elevation of the PCr resonance, a decrease in PDE and an increase in intracellular pH. The monitoring showed that the metabolites approached steady state approximately 2 hr after the fractionated radiation intervention, suggesting that in vivo MRS can be useful for studying the dynamics of tumor response to RT such as repair of potential lethal damage, growth delay, and reoxygenation etc. The steady-state MR spectra showed the net response to each intervention and can clinically be useful for predicting and ...

International Nuclear Information System (INIS)

Thermal diffusivity was measured with a laser flash method up to 2000 K for UO_2 pellets irradiated in a commercial reactor. Measurements were done on micro samples of disks (2 mm diameter) or regular prisms (1.5 or 2 mm square cross sections). Thermal diffusivity degraded on extending burnup in agreement with reported values for UO_2 irradiated in test reactors, and it showed hysteresis during the laser flash experiments. Thermal diffusivity began to recover above 750 K and almost completely recovered above 1400 K, which corresponded with the reported radiation damage recovery. The obtained data were in agreement with predictions applying the thermal conductivity expression for irradiated UO_2 proposed by Amaya and Hirai. The sample experiencing power ramp showed higher thermal diffusivity than that of the base irradiated sample and had no obvious hysteresis. This suggested that the radiation damage ...

International Nuclear Information System (INIS)

This paper provides a physically-based engineering model to estimate radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades but incorporating a number of assumptions and simplifications [Trinkaus, J. Nucl. Mater. 318 (2003) 234-340]. As a result, the kinetics of the damage accumulation kept fixed, its amplitude is fitted on one experimental condition. The model was rationalized on an experimental database that mainly consists of ?9%Cr-steels irradiated in the range of 50-600 deg. C up to 50 dpa and with a He-content up to 5000 appm. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Despite the large experimental scatter, ...

International Nuclear Information System (INIS)

There are very different views on the health hazards of DU munitions. Most of the concerns of veterans and their advisors focus on the radiological effects of DU and consequently these are the focus of this editorial. Effects on the kidney and environmental consequences are, however, considered in the second of the Royal Society reports and the main conclusions of both of the reports are outlined in the summary document published in this issue of the journal. The main radiological concerns focus on the irradiation of lung tissues from inhaled DU particles and irradiation resulting from the translocation of inhaled particles to the thoracic lymph nodes.The overwhelming scientific view, presented in the two Royal Society reports and in other independent reviews, is that the main risks of exposure to DU aerosols are an increase in lung cancer and (from chemical toxicity) damage to the kidney, although these are likely to be evident only following substantial intakes. ...

Energy Technology Data Exchange (ETDEWEB)

Two patients are described in whom sunburn and electron beam radiodermatitis, respectively, were critical determinants in localizing the initial presentation of drug eruptions. In the first instance, a severe sunburn of the back and thighs was followed 7 months later by the appearance of a toxic epidermal necrolysis drug reaction to trimethoprim-sulfamethoxazole in the exact sites of the previous bullous sunburn reaction. In the second patient, a radiodermatitis of the left upper arm due to electron beam therapy for metastatic breast cancer was followed 7 weeks later by a codeine drug reaction confined to the area of the radiodermatitis. In both instances, oral rechallenge with the offending drug reproduced the eruption.

International Nuclear Information System (INIS)

The emission of Cerenkov radiation by tachyons has been examined by using the reduced expansions of superluminal electromagnetic fields in terms of standard helicity representation of Poincare group. It has been shown that the tachyons emit Cerenkov radiation through their coupling only with subluminal electromagnetic fields and that a charged tachyon can emit Cerenkov radiation only in the media in which it travels with a velocity lower than that of light while in the usual medium in which its velocity is more than that of light, it will never emit Cerenkov radiation. (author).

British Library Electronic Table of Contents (United Kingdom)

In Korea, the Proton Engineering Frontier Project (PEFP) is building a proton linear accelerator facility with energy up to 100MeV and a beam current of 20mA. In this study, a radiation field after shutdown in the accelerator facility of the PEFP was evaluated for the purpose of the radiation shielding by using MCNPX code. A facility modeling was performed for the accelerator tunnel building, accelerator chain, target rooms and beam experiment hall. And radiation source terms were evaluated in the facility. With this facility, model and radiation source terms, the concentration of 41Ar was evaluated and the cooling time satisfying regulation in Korea was calculated.

CERN Document Server

We formulate a complete theory of Edge Radiation based on a novel method relying on Fourier Optics techniques. Similar types of radiation like Transition Undulator Radiation are addressed in the framework of the same formalism. Special attention is payed in discussing the validity of approximations upon which the theory is built. Our study makes consistent use of both similarity techniques and comparisons with numerical results from simulation. We discuss both near and far zone. Physical understanding of many asymptotes is discussed. Based on the solution of the field equation with a tensor Green's function technique, we also discuss an analytical model to describe the presence of a vacuum chamber. In particular, explicit calculations for a circular vacuum chamber are reported. Finally, we consider the use of Edge Radiation as a tool for electron beam diagnostics. We discuss ...

International Nuclear Information System (INIS)

The optically stimulated luminescent (OSL) radiation dosimeter technically surveys a wide dynamic measurement range and a high sensitivity. Optical fiber dosimeters provide capability for remote monitoring of the radiation in the locations which are difficult-to-access and hazardous. In addition, optical fiber dosimeters are immune to electrical and radio-frequency interference. In this paper, a novel remote optical fiber radiation dosimeter is described. The optical fiber dosimeter takes advantage of the charge trapping materials CaS:Ce, Sm that exhibit OSL. The measuring range of the dosimeter is from 0.1 to 100 Gy. The equipment is relatively simple and small in size, and has low power consumption. This device is suitable for measuring the space radiation dose and also can be used in high radiation dose condition and other dangerous radiation occasions. ...

International Nuclear Information System (INIS)

The world fusion program has advanced to the stage where it is appropriate to construct a number of devices for the purpose of burning DT fuel. In these next-generation experiments, the expected flux and fluence of 14 MeV neutrons and associated gamma rays will pose a significant challenge to the operation and diagnostics of the fusion device. Radiation effects include structural damage to materials such as vacuum windows and seals, modifications to electrical properties such as electrical conductivity and dielectric strength and impaired optical properties such as reduced transparency and luminescence of windows and fiber optics during irradiation. In preparation for construction and operation of these new facilities, the fusion diagnostics community needs to work with materials scientists to develop a better understanding of radiation effects, and to undertake a testing program aimed at developing workable solutions for ...

Energy Technology Data Exchange (ETDEWEB)

Gonadal function was studied in two groups of children previously treated for medulloblastoma with surgery followed by postoperative craniospinal irradiation. In group 1 but not in group 2, the children also received adjuvant chemotherapy for one to two years. All children in group 1 received a nitrosourea (BCNU or CCNU), plus vincristine in four and procarbazine in three patients. The nine children in group 1 showed clinical and biochemical evidence of gonadal damage with elevated serum FSH concentrations and, in the boys, small testes for their stage of pubertal development. In group 2 (n . 8), each child had completed pubertal development normally, the boys had adult sized testes and the girls regular menses. Gonadotropin values were normal in all eight children. We conclude that nitrosoureas were responsible for the gonadal damage in the children in group 1, with procarbazine also contributing to the ...

International Nuclear Information System (INIS)

Terminal-differential algorithm for identification of local nonhomogeneities in items under control is developed on the basis of measurements of X-ray or gamma-radiation weakening. The algorithm may be applied by developing radiation schemes of nondestructive control, identifying inadmissible inclusions in the object under study

UK PubMed Central (United Kingdom)

BackgroundThe aim of this study was to compare and to validate different dose calculation algorithms for the use in radiation therapy of small lung lesions and to optimize the treatment...Full Text Available

International Nuclear Information System (INIS)

In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the #beta# chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.

International Nuclear Information System (INIS)

The present study was designed to assess the radioprotective effects of amifostine on ovarian follicles. Three week-old female mice with or without pretreatment of amifostine were irradiated with 6.42 Gy of #gamma# -ray. Ovaries were collected 0 and 6h after irradiation. DNA fragmentation pattern and expression of genes and activity of proteins related with apoptosis were investigated by means of RT-PCR and Western blot. Proliferation of granulosa cells was reduced and incidence rate of follicular atresia was increased in ovarian follicles in #gamma# -ray irradiated mice compared to those in control or amifostine-treated group. DNA fragmentation was increased in time-dependent manner in granulosa cells of all irradiated groups. However, no difference between amifostine pre-treated group and irradiated groups was found and the expression of p53 as tumor suppressor gene and Bax as one of pro-apoptotic Bcl-2 family was increased in irradiated mice ovaries. PARP as DNA ...

International Nuclear Information System (INIS)

The incidence of hilar cholangiocarcinoma is very rare worldwide. Radical resection is the only prognostic factor for long survival in patients with hilar cholangiocarcinoma. Postoperative radiation therapy can improve local control and survival rates for patients with palliative resection, but it remains controversial in patients with radical resection. Biliary drainage can effectively release bile duct obstruction for the majority of patients with locally advanced disease, and may even prolong survival when combined with radiation therapy. Radiation therapy includes extrernal beam therapy alone, external beam therapy with intraluminal brachytheapy and new radiation technique, such as three dimentional conformal therapy and intensity modulated radiation therapy. The propective randomized clinical study is needed for further investigation in the role of combined ...

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe{sup 2+} ions at RT produced amorphization in the implanted ion region after damage levels of {similar_to}1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He{sup +} ions at ...

Energy Technology Data Exchange (ETDEWEB)

The effect of adriamycin in combination with radiation on the skin reactions of mouse feet has been examined under a variety of experimental conditions including: (a) hyperthermic treatment of the foot immediately following adriamycin administration, with the former given either just before or just after x irradiation, and (b) fractionated treatments of drug and radiation in a variety of sequences over an 18-day period. In the case of the most severe hyperthermic treatment, no increased radiation reactions were observed in the presence of adriamycin. However, in the case of the less severe hyperthermic treatment a small but significant increase in skin reactions was observed. In the study of fractionated drug and radiation treatments, an enhancement of reaction in those animals receiving combined modality treatment over those receiving radiation alone was seen ...

Energy Technology Data Exchange (ETDEWEB)

In searching modulators of immunity and hematopoiesis among natural products, being used as foods, six herbs exhibited lymphocyte proliferation in vitro, and six exhibited augmentation of hematopoietic cell growth. The combined treatments showed synergistic effects of lymphocyte proliferation and of hematopoietic cell growth. On the other hand, we found four effective oriental medicinal prescriptions, used as energy tonic or blood-building decoctions, for survival and regeneration of hematopoietic cells and for protection of stem cells of intestinal crypt in irradiated mice. On the basis of these results, extracts from combinations of herbs were made in expectation of higher effects in the three respects. In immuno modulation activity by the two combinations of herbs was confirmed in mice. In culture of bone narrow cells, growth improvement of non-adherent precursor and induction of cytokine expression by herb mixture extracts were observed. In evaluation of fractions, polysaccharide ...

International Nuclear Information System (INIS)

The radiation hardening studies started in the mid decade 1960-1970. To survive the different military or space radiative environment, a new engineering science was born, to understand the degradation of electronics components. The different solutions to improve the electronic behavior in such environments have been named 'radiation hardening' of the technologies. Improvement of existing technologies, and qualification methods have been widely studied. However, on the other hand, specific technologies were developed: the Silicon On Insulator technologies for CMOS or Bipolar. The HSOI3HD technology offers today the highest hardening level for the integration density of hundreds of thousand transistors on the same silicon. Full complex systems could be produced on a single die with a technological radiation hardening and no more system hardening.

Science.gov (United States)

... mass of gray gas by thermal radiation; An experimental study of the turbulent wake behind a cone at M = 5; Heat transfer augmentation by steady ...

Energy Technology Data Exchange (ETDEWEB)

A necessary condition for crevice corrosion is that a crevice former create a sufficiently tight, restricted geometry on the metal surface to support the development of critical crevice chemistry. Crevice corrosion is affected by the crevice geometry (tightness) and the properties of the crevice former. The objective of this study is to determine the effect of the crevice former material on the evolution of localized corrosion-damage. A standard crevice corrosion test method is modified by (a) the use of ceramic, metal or polymer materials as the crevice former and (b) the variation of size and shape of the crevice. This study focuses on the post initiation stage of crevice corrosion and addresses factors that may limit the initiation of localized corrosion and also slow or stop the continued propagation of corrosion. Controlled crevice corrosion tests are performed under aggressive, accelerated conditions on Ni-Cr-Mo alloy ...

International Nuclear Information System (INIS)

A previous study described the basic theoretical expectations of the magnetic dipole radiation and unipolar induction of pulsars and presented observational results. This paper further discusses the difference between the two braking mechanisms and analyses the results of a statistical study through observed data of apparent beamwidth's distributions and a geometrical method. The theory of magnetic dipole radiation of pulsars agrees with the observations. Unipolar induction as a braking mechanism is not consistent with the observations.

International Nuclear Information System (INIS)

Technique, allowing to investigate straggling zone (full braking) from high-energy charged particles in detail, is described. Experimental results on investigation of efective structure, created in polycrystalline molybdenum (99.97%) within 29 MeV alpha-particles straggling zone for fluences from 3.8x10"1"9 up to 3.7x10"2"1 #alpha#/m"2 by methods of microhardness (H_#mu#, X-ray structural analysis (#DELTA#a/a) and transparent electron microscopy (TEM), are presented. It is determined, that for doses from 3.8x10"2"0 #alpha#/m"2 and higher, at #approx#6 MeV energy, molybdenum ''softening'' is observed, H_#mu# curve within straggling zone is well described by alloyage calculated profile. #DELTA#a/a measurements within straggling zone are well described by damage profile. TEM-investigations have shown the developed defective structure even within molybdenum ''softening'' range.

International Nuclear Information System (INIS)

In support of Stockpile Stewardship activities, accelerated aging tests on a plutonium alloy enriched with 7.3 at.% of "2"3"8Pu is underway using dilatometry at 35, 50, and 65 deg. C and immersion density measurements of materials stored at 50 deg. C. Changes in density are expected from radiation damage in the lattice and helium in-growth. After 25 equivalent years of aging, the dilatometry data shows that the alloys at 35 deg. C have expanded in volume by 0.11-0.12% and have started to exhibit a near linear expansion behavior primarily caused by the helium accumulation. The average He-to-vacancy ratio from tested specimens was determined to be around 2.55. The model for the lattice damage and helium in-growth accurately represents the volume swelling at 35 deg. C. The density converted from the dilatometry corresponds well to the decreasing density trend of reference plutonium alloys as a function of time.

Science.gov (United States)

Laser devices are currently in widespread use in particular by armed forces for different tasks. Electro-optical sensors as well as unprotected human eyes are extremely sensitive to laser radiation and can be permanently damaged from direct or reflected beams. Laser damage depends on the interaction between the laser beam and the atmosphere in which it traverses. The atmospheric conditions, including the range, terrain features, turbulence, and atmospheric particulates, may alter the laser's effect on different electro-optical devices and systems. When a laser beam passes through the atmosphere the optical turbulence affects the beam. As a result, temporal intensity fluctuations (scintillations) or spatial variations in intensity within a beam cross-section occur. Atmospheric scintillations pose a safety problem because an observer or sensor can be subjected to the risk of a localized irradiance (local focusing effect) much ...

Energy Technology Data Exchange (ETDEWEB)

Correlation between mechanical stress and hydrogen effects on radiation damage in polycide-gate MOS capacitors was investigated as a function of gate-oxide thickness. The compressive stress magnitude was altered by varying the silicide (TiSi/sub 2/ or WSi/sub 2/) thickness in the polycide-gate electrode, and hydrogen introduction into gate-SiO/sub 2/ film was carried out by diffusion from plasma-deposited silicon-nitride passivation film (SiN-Cap). In a MOS capacitor without passivation film (No-Cap sample), it was found that compressive stress on gate-SiO/sub 2/ reduces both positive charge build-up (..delta..Qot) and interface-trap generation (..delta..Dit). Radiation induced shift, ..delta..Qot exhibits a smaller stress effect as compared with ..delta..Dit. As gate-SiO/sub 2/ thickness decreases, the stress effect on ..delta..Qot increases, while this effect on ..delta..Dit remains nearly constant. This compressive ...

Energy Technology Data Exchange (ETDEWEB)

Population residing in the northern part of the Chelyabinsk oblast and the south eastern part of the Sverdlovsk oblast of Russia affected to accidental exposure since 1957. The territory (East Ural Radioactive Trace - EURT) was contaminated after explosion of container with highly radioactive wastes at the Mayak Production Association. Studies of health effects of exposure in the southern, head part of EURT are conducted in the Ural Research and Practical Center of Radiation Medicine (U.R.P.R.M.). In the 1990's U.R.P.C.R.M. formed a cohort of EURT within Chelyabinsk oblast (14,500 cases and 19,400 external controls). The cohort was followed in 1957-1987 and the results of the study are discussed by Crestinina et al. First results of study on exposure late health effects among rural population in the northern part of the EURT are presented in this paper. Firstly, or the period 1958-2000 a ...

International Nuclear Information System (INIS)

Some studies suggest that giving radiation therapy after surgery for hilar cholangiocarcinoma improves the survival rate; however, many of these studies did not specify numbers of subjects or provide an impartial analysis. Thus, we evaluated the effectiveness of radiation therapy as adjuvant treatment after surgery and attempted to establish appropriate adaptation standards. We reviewed the records of 69 patients who underwent surgery for hilar cholangiocarcinoma between June 1980 and April 1998. Thirty-nine patients were treated with surgery followed by radiation therapy and 30 were treated with surgery alone. The clinicopathologic features that might have influenced prognosis were similar in the patients who received radiation therapy and those who did not. Radiation as adjuvant therapy did not have a beneficial effect on overall survival ...

Energy Technology Data Exchange (ETDEWEB)

In attempting to detect and map out underground facilities, whether they be large-scale hardened deeply-buried targets (HDBT's) or small-scale tunnels for clandestine border or perimeter crossing, seismic imaging using reflections from the tunnel interface has been seen as one of the better ways to both detect and delineate tunnels from the surface. The large seismic impedance contrast at the tunnel/rock boundary should provide a strong, distinguishable seismic response, but in practice, such strong indicators are often lacking. One explanation for the lack of a good seismic reflection at such a strong contrast boundary is that the damage caused by the tunneling itself creates a zone of altered seismic properties that significantly changes the nature of this boundary. This report examines existing geomechanical data that define the extent of an excavation damage zone around underground tunnels, and the potential impact on rock ...

Energy Technology Data Exchange (ETDEWEB)

Slow, unexpected displacements have been experienced in most pressurized water reactor (PWR) surge lines. Sometimes, these displacement lead to gap closure at the pipe whip restraints. These movements occur because of thermal stratification. This movement has the potential to increase stresses to valves, which may exceed the material yield stress. To understand this phenomenon, Framatome, Commissariat a l'Energie Atomique, and Electricite de France have undertaken large programs for the study of (1) thermal-hydraulic tests with a half-scale Plexiglas surge line, (2) thermal-hydraulic computations of permanent states and transients with a two-dimensional model, and (3) mechanical analysis of displacements and computation of fatigue damage due to stratification. This paper deals with the last subject. Avoiding stratification in piping by process modifications is difficult because of the high flow rate needed. Alternative solutions for ...

Energy Technology Data Exchange (ETDEWEB)

The performance of advanced ceramics under cavitation loading in distilled water was studied by using a laboratory test with vibration-induced cavitation following the pattern of the ASTM standard G32-92. The hardened and tempered martensitic steel 100Cr6 was used as a reference. The aim was to identify mechanisms and the effects of important microstructural parameters on damage of polished Al{sub 2}O{sub 3}, Al{sub 2}O{sub 3}-ZrO{sub 2}, ZrO{sub 2} and SiC ceramics. Results showed that surface damage of brittle ceramics was mainly dominated by intergranular fracture, followed by detachment of single grains or fragments of them. Both incubation time and erosion rate were affected by the amount of initial surface cavities, grain sizes and secondary phases at grain boundaries. (orig.)

International Nuclear Information System (INIS)

The study required by the West German Ministry of Research and Technology (RS 605) for the Committee on 'Future Nuclear Energy Policy' of the 9th German Parliament is concerned with the following main points: 1) Assessment of technical risks from the social aspect; 2) Discussion of terms and quantification of risks; 3) 'Engineering judgment' and 'questionable' methods in the Fast Breeder analysis of the Society for Reactor Safety (GRS); 4) Assessment criteria of potential damage. (HP).

International Nuclear Information System (INIS)

In spite of extensive cooling water studies premature damage due to corrosion occurred on the CuZn20Al condenser tubes. It was then decided to incorporate new titanium-tubed condensers during the annual overhauls of 1983 and 1985 and also take ameliorating measures up to the exchange of individual condensers. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Steam generators (SG) are the weak link of nuclear power plants, their service life is shorter than the service life of other NPP components. This paper is dedicated to a statistical analysis of SG damages and failures. Heat exchanging tubes (HET) are the most damaged elements in SG, there are on average 286 plugged or repaired tubes in each operating SG. The usually mechanisms of tube failure are the following: denting, corrosion at tube outside, pitting, fretting, and circular crack propagation. Most of damages are located in the transition zone above a tube plate. This study shows that the factors that are involved in the SG HET fault probability are: - design features of SG and secondary equipment elements (high pressure feed heaters (HPFH), low pressure feed heater (LPFH)), - water chemistry at different points of condensate feed pipe, composition and density of deposits on HET surface, efficiency ...

Energy Technology Data Exchange (ETDEWEB)

Langmuir-Blodgett (LB) preparations containing stacked monolayers of phospholipids or stearic acid were irradiated with UV light and the electric conductance perpendicular to the planes of the monolayers was measured. There was no observable change of conductance when LB preparations of stearic acid were irradiated. For LB preparations of phospholipids, a rise of conductance, dependent on dose rate, was observed, reaching an equilibrium level after a few hours. After irradiation the conductance fell with a temperature-dependent time constant, and eventually reached a final level a little above the initial value. A three-state model is proposed for the LB phospholipid preparations. This suggests that the absorption of one photon raises a molecule from the ground to an excited state; and the absorption of a second photon carries it into a damaged but repairable or metastable state. (author).

British Library Electronic Table of Contents (United Kingdom)

An energy transfer and conversion model for high-temperature solar cavity receivers has been developed using the transport behaviour of solar radiation as described by the spectral radiative exchange factors. A Monte-Carlo ray-tracing method coupled with optical properties was adopted, to predict radiation characteristics of the solar collector system by calculating radiative exchange factors. A cavity receiver with a plano-convexo quartz window was proposed, based upon the directional characteristics of the focal flux and the redistribution effect of the quartz window. Parametric studies on the windowed receiver provided a more uniform flux distribution, higher efficiency and lower loss than the windowless receivers. The predicted results serve as a design reference for the solar receiver...

Energy Technology Data Exchange (ETDEWEB)

Regularities in the radiation cross-linking of low-density polyethylene under various conditions of ..gamma..-irradiation were studied. It is shown that at the 0.5 GPa pressure and 450 K the gel formation is initiated at doses of about 1 kGy, i.e. at doses 10 times as low as compared to normal conditions. Abnormally high rate of radiation cross-linking at high temperature and high pressure is an evidence of changes in the mechanism of polyethylene, radiation cross-linking, i.e. of the process transition from nonchain to chain conditions. Decrease in the potential barriers of macroradical reactions with macromolecules is the most probable reason of change in the polymer cross-linking nature.

International Nuclear Information System (INIS)

Experimental investigation data are systematized of free radical states and processes in irradiated proteins. The investigation is performed by the radiospectral methods. Results are discussed in detail of the study of free radicals electronic structure of amino acids, peptides and proteins formed by the action of ionizing radiation. The specificity is stressed of the study of monocrystalls of these compounds by the method of electronic paramagnetic resonance. The nature is also studied of primary centres formed under the effect of radiation on biologically important compounds and their subsequent reactions in solid and liquid solutions. Ion-radical states of different functional groups of the protein molecule are studied. Prospects of the study and the role of anion-radicals in biological processes are discusses.

Energy Technology Data Exchange (ETDEWEB)

Dose-dependent behavior of the infrared stimulated luminescence (IRSL) decay from NaCl has been studied experimentally using only one aliquot irradiated with a range of 2-200 Gy {beta}-radiation doses. It was observed that the maximum IRSL intensity has not changed by an increase in dose though the total intensity increased as expected. Considering the possible implications of our findings for dosimeter, the results were compared with the other studies and discussed.

Energy Technology Data Exchange (ETDEWEB)

This paper reports the study results on the standard weather data necessary for simulation of PV power generation systems in fiscal 1994. In the study on the selection criterion of the standard weather data from the viewpoint of PV power generation systems, three typical years are used; a year with average solar radiation, and two years with extremely less and more solar radiation for safe simulation. The standard weather data are arranged for output calculation of PV power generation systems by selecting the most typical year based on long-term observation data. The data to be arranged are as follows; total, direct and scattered solar radiations incident upon a horizontal surface, solar radiation upon a slope surface, sunshine duration, air temperature, wind direction, wind velocity, amount of precipitation, and snow depth. For arrangement of the nationwide ...

UK PubMed Central (United Kingdom)

Thus far there are relatively few data on the risk of leukemia among those who were exposed to external radiation during cleanup operations following the Chornobyl nuclear accident, and results...Full Text Available

International Nuclear Information System (INIS)

The scattering of atoms by a resonance standing light wave is considered under conditions when the lower of two resonance levels is metastable, while the upper level rapidly decays due to mainly spontaneous radiative transitions to the nonresonance levels of an atom. The diffraction scattering regime is studied, when the Rabi frequency is sufficiently high and many diffraction maxima are formed due to scattering. The dynamics of spontaneous radiation of an atom is investigated. It is shown that scattering slows down substantially the radiative decay of the atom. The regions and characteristics of the power and exponential decay are determined. The adiabatic and nonadiabatic scattering regimes are studied. It is shown that the wave packets of atoms in the metastable and resonance excited states narrow down during scattering. A limiting (minimal) size of the wave packets is found, ...

International Nuclear Information System (INIS)

The authors have measured the magnetization of single-phase 90-K superconductors, GdBa_2Cu_3O/sub 6+#delta#/, EuBa_2Cu_3O/sub 6+#delta#/, and SmBa_2Cu_3O/sub 6+#delta#/ with a SQUID magnetometer. They have shown that, in the superconducting state, each magnetization-field curve exhibits a maximum at #approx# 100 G, followed by a linear increase of the magnetization with a slope only approximately one-fifth of the slope for a field smaller than 50 G. They have also investigated the effect of #gamma#-irradiation on YBa_2Cu_3O/sub 6+#delta#/, SmBa_2Cu_3O/sub 6+#delta#/, and have found that the radiation damage results in the appearance of a tail in the superconducting transition. They have also shown that the normal resistance decreases with increasing radiation exposure up to a dose of 10 Mrad.

International Nuclear Information System (INIS)

The Sp-100 reactor is a lithium-cooled high-temperature fast-spectrum reactor. The fuel is UN. The cladding is fabricated from PWC-11, a Nb alloy, as are all the primary structural components. A reactor lifetime of up to ten years with an operating temperature of 1370 K is required. The accumulated fluence is expected to be 6 x10"2"2 n/cm"2. The damage, which could result in swelling or embrittlement, anneals out as fast as it occurs for the majority of the structure. This has been confirmed by earlier radiation testing. A number of components, however, are exposed to lower temperatures and the reactor design and materials selection for these components must take this into consideration. Radiation effects must also be considered for the UN fuel, bearing materials, etc. To data an instrumented experiment, MOTO 1000A, has been conducted in the FFTF reactor and as uninstrumented experiment SPM-1 in the EBR-II reactor. In this ...

International Nuclear Information System (INIS)

The results of studies of radiation-thermocatalytic water decomposition in the 673-773 K temperature range in the presence of BeO and titanium Y-type zeolite are presented. It is found that radiation-thermocatalytic processes of hydrogen production from water are characterized by a lower activation energy (55.4 kJ/mole) as compared with thermocatalytic processes (88.4 kJ/mole). The radiation-thermocatalytic process rate in the presence of oxide systems is not an additive sum of rates of radiation-catalytic (at 296-300 K) and thermocatalytic processes of water decomposition. On the basis of obtained results the conclusion is made that during radiation-catalytic decomposition of water in a heterogeneous system BeO + H_2O the main contribution into this process is made by excitons, radiation-chemical yields of excitons and non-equilibrium ...

International Nuclear Information System (INIS)

Exposures from most natural and artificial sources, with the exception of those from medical radiology, are received at average dose rates of only a few microsieverts a day. Such risks as may be caused by these exposures are most unlikely to be determined with precision directly by epidemiological studies of populations exposed at these low rates. They may, however, be reliably inferred from the observed risks of exposure to rather larger doses delivered at higher dose rates in the light of the increasing knowledge of the phenomena involved in the initial cellular damage, the extent to which such damage is incorrectly repaired, and the processes which intervene between the genetic or other harm to cells and the likelihood of its final expression in inherited abnormality, in cancer development, or in defective foetal or embryonic growth. Current studies are of great importance, therefore, in examining ...

International Nuclear Information System (INIS)

One of the main problems related to optical thin film materials used in high power laser environments is the catastrophic damage caused to them due to laser irradiation. While the influence of ion bombardment on the optical properties of oxide thin films is now a well understood subject, the morphology and crystalline behaviour of these films under ion incidence is not so well studied. Hence, it is of great importance to investigate the effects of ion bombardment during growth on the microstructure and crystalline behaviour of oxide materials.

Science.gov (United States)

Endothelial dysfunction and increased platelet aggregation may be involved in the pathogenesis of normal tissue radiation toxicity. This study assessed clopidogrel, an inhibitor of ADP-induced platelet aggregation, as a modulator of intestinal radiation injury (radiation enteropathy). Rat small intestine was exposed to 21 Gy X-radiation. Clopidogrel (20 mg/kg/day) or vehicle was administered from 2 days before to 10 days after irradiation. Structural radiation injury, neutrophil infiltration, smooth muscle cell proliferation, collagen content, and TGF-beta1 expression were assessed 2 weeks (early phase) and 26 weeks (delayed phase) after irradiation, using quantitative histology and immunohistochemistry, morphometry, and real-time fluorogenic probe RT-PCR. Irradiated intestine exhibited significant histopathologic injury, reduced mucosal surface area, vascular ...

British Library Electronic Table of Contents (United Kingdom)

Resonant scattering of atoms with formation of the Feshbach resonance in the presence of a laser radiation coupling the levels of two bound atoms (a molecule) is considered. The laser field leads to a second resonance in scattering and broadening of resonances, which facilitates the possibility of experimental observation of asymmetry of the total scattering cross-section arising because of interference between resonant and potential scatterings. The effects associated with interference of the two channels of decay of a bound system of two atoms (a molecule) in the laser field are studied. An expression is obtained for the scattering length in collision of two cold atoms in the field of laser radiation.

International Nuclear Information System (INIS)

Feasibility of using sterile females for population suppression of Earias vittella (Fabricius) was evaluated by conducting studies on mating competitiveness of radiation sterilized females, both in individual pairs and in simulated large population conditions. Results showed that sterility induced by using a 10:1:1 ratio (sterile female: normal female: normal male) in single pair experiments and also in simulated large population conditions was more than 99.0 per cent. Release of radiation- sterilized females of E. vittella in natural populations has thus an excellent potential for population suppression. (author)

International Nuclear Information System (INIS)

Spectra of e.p.r. radicals in cellulose and timber gamma-irradiated at 77 and 300 K have been measured. Radiation yields and the kinetics of radicals accumulation have been studied. The effect of ionizing radiation on cellulose is the appearance of radicals resulting from rupture of C-H bonds in positions 1 and 4. Timber, additionally, forms ''lignin'' radicals. A mechanism of cellulose and timber radiolysis is suggested. ''Lignin''-type compounds present in timber protect polysaccharides from radiation-induced destruction.

Science.gov (United States)

The waterjet technique enables precise tissue dissection without thermal damage and with preservation of vessels in general surgery. In neurosurgery, these qualities could help to avoid damage of intact brain parenchyma in tumour resections. The present study reports our first results with this technique in brain metastases. Ten patients with intracranial metastases underwent surgery with the aid of the waterjet. Resection was performed in combination with conventional neurosurgical methods. The follow-up consisted of neurological examination and MRI studies. Intraoperatively, the device was easy to handle. No complications due to the device were observed. Vessels were preserved at pressures below 20 bars. Six of the tumours consisted of soft tissue which was poorly demarcated from the surrounding brain. In these tumours, the waterjet was very helpful. It enabled tumour debulking by aspiration and - ...

Energy Technology Data Exchange (ETDEWEB)

Large-scale field tracer experiments have been conducted on Ulchin, Wolsung and Daeduk sites for the purpose of validating FADAS and of analyzing the environmental characteristics around the nuclear sites. The most influential factor in atmospheric dispersion is the meteorological condition. During the experiment, meteorological data were measured on the release point and the selected positions among sampling points. Once radioactive materials are released to the atmosphere, members of public may be exposed through the environmental media such as air, soil and foods. Therefore, to protect the public, adequate countermeasures should be taken at due time for those exposure pathways. both processes, of justification and optimization are applied to a countermeasure simultaneously for decision-making. The work scope of Biological research for the radiation protection had contained the search of biological microanalytic methods for assessing the health effect by ...

Energy Technology Data Exchange (ETDEWEB)

Having simple and highly symmetric structure, solid hydrogen is a useful matrix on the study of radiation-chemical processes in solid phase which have been less understood in previous studies. We have found three outstanding findings: resonance effects on the tunneling reaction H+H{sub 2} {yields} H{sub 2} + H, effects of pressure on the dissociation and recombination of H{sub 2} molecules in solid hydrogen, and high-resolution ESR spectroscopy using a solid parahydrogen matrix. (author)

International Nuclear Information System (INIS)

Practical procedures were developed for large-scale microbial decontamination of dry egg powder and gelatine with gamma radiation ("6"0Co). The formation and lifes of free organic radicals in these materials were examined by ESR measurements of powder samples. The concentration of these radicals was studied in dependence on the time of storage. Secondary oxidation of egg fats by air oxygen was investigated. Sensoric tests of irradiated gelatine, both in powder and hydrogel form, were performed. (author). 4 figs., 2 tabs., 2 refs.

Energy Technology Data Exchange (ETDEWEB)

Energy spectra of the Bragg reflection of the Moessbauer ..gamma..-radiation from the /sup 57/Fe/sub 3/BO/sub 6/ weakly ferromagnetic monocrystal are studied. A strong effect of the interference transitions in iron nuclei, being in non-equivalent positions, on the spectra form is revealed. The measurement results are compared with theoretical calculations.

Energy Technology Data Exchange (ETDEWEB)

Collisional-Radiative numerical models are commonly used to design or interpret experiments in atomic physics of laser-created plasmas, including X-ray laser studies. We describe our new code containing several options: average ion, more or less detailed configurations. It consists of an atomic data base coupled to subroutines evaluating ionic populations and emission and absorption coefficients. Numerical results are given to illustrate the capabilities of the code and to compare different models and types of approximation.

Energy Technology Data Exchange (ETDEWEB)

High energy physics facilities must monitor the radiation doses received by their personnel. This monitoring can only be effective if the radiation detection devices can be calibrated with a good degree of accuracy. Radiation fields are usually composed of several types of radiation, including gamma rays, beta radiation, neutrons, etc. The neutron detection instruments respond not only to the neutrons coming directly from the source but also those scattered from the floor, walls, and ceiling. The amount of neutron scattering varies from site to site depending on the construction materials and layout of the building. The purpose of this study was to determine the scattered neutron fraction in the central volume of the calibration mezzanine of the Radiation Physics Calibration Facility (RPCF) at the Fermi National Accelerator Laboratory ...

International Nuclear Information System (INIS)

A study of the influence of the concentration of secondary addition, high concentrations of primary dopant, diffusion enhancer and stabilizer on radiation hardness is presented. It is concluded that the diffusion enhancing technique is the most powerful method for improving radiation hardness. A new polystyrene scintillator which contains 2% pT, 0.02% POPOP, 20% diffusion enhancer and 0.02% stabilizer gave 91% of initial light output immediately after 3 Mrad irradiation in air. Data are presented that show that scintillator prepared from commercial polymer is more radiation-hard and has greater light output than scintillator prepared from monomer. It is assumed that this difference is due to different molecular weight distributions. Some protocols for acceleration of aging (yellowing and crazing) are presented. It is shown that one of the main reasons for aging of plastic scintillators is residual ...

British Library Electronic Table of Contents (United Kingdom)

Plants require solar radiation for photosynthesis and their growth is directly related to the amount received, assuming that other environmental parameters are not limiting. Therefore, precise estimation of photosynthetically active radiation (PAR) is necessary to enhance overall accuracies of plant growth models. This study aimed to explore the PAR radiant flux in the San Francisco Bay Area of northern California. During the growing season (March through August) for 2?years 2007?2008, the on-site magnitudes of photosynthetic photon flux densities (PPFD) were investigated and then processed at both the hourly and daily time scales. Combined with global solar radiation (R S) and simulated extraterrestrial solar radiation, five PAR-related values were developed, i.e., flux density-based PAR ...

International Nuclear Information System (INIS)

Radiation technology offers a very wide scope for utilisation and commercial exploitation in various field. All over the world, this technology is being favourably considered for different applications like radiation sterilisation of medical products, preservation of food by controlling the physiological processes for extending shelf-life and eradication of microbial and insect pests, radiation processing of polymeric materials and treatment of sewage sludge. Bangladesh Atomic Energy Commission has taken radiation processing programmes in a big way right from its inception. This paper describes the studies carried out by various research groups in Bangladesh Atomic Energy Commission mainly using Cobalt-60 gamma radiation. The investigation covers medical sterilisation, food preservation and development and modification of polymeric materials by gamma ...

Energy Technology Data Exchange (ETDEWEB)

This report concerns investigations in the title conducted by 8 groups of National Institute of Radiological Sciences (NIRS) during the period of 1998-2000. The groups are for investigation of: Effects of p53 tumor suppressor gene in radiation-induced leukemia, Role of atm-gene in dose rate effect of ionizing radiation, Function of DNA-dependent protein kinase catalytic subunit (DNA-PK{sub cs}), Functional complementation of radiation-sensitive mutant M10 cell line by human XRCC4 cDNA expression, Role of radiation-induced apoptosis in digital defects in embryonic mice, Functional analysis of S-phase specific novel nuclear protein NP95 by gene targeting, Role of chemokine in T cell development and lymphomagenesis, and establishment of production techniques of gene-modified mice using embryonic stem cells for genetic analysis of radiation-sensitive genes. The groups describe summaries ...

International Nuclear Information System (INIS)

... organizations irradiation radiation doses radiation effects RADIATIONS.

International Nuclear Information System (INIS)

... halogenation ionizing radiations kinetics radiations reaction kinetics

Energy Technology Data Exchange (ETDEWEB)

Swift heavy ion-solid interaction leads in volume to track creation and on the surface to the ejection of particles into the vacuum. To learn more about initial mechanisms of track formation, we are focused on the sputtering of uranium dioxide by fast heavy ions. This present study is exclusively devoted to the influence of the electronic stopping power on the emission of neutral particles and especially on their angular distribution. These measurements are completed by those of the ions emitted from UO{sub 2} targets bombarded with swift heavy ions. The whole experimental results give access to: i) the nature of the sputtered particles; ii) the charge state of the emitted particles; iii) the direction of ejection of the sputtered particles ; iv) the sputtering yields deduced from the angular distributions. These results are compared to the prediction of the sputtering models proposed in the literature and it seems that the supersonic gas flow model is well suited ...

UK PubMed Central (United Kingdom)

Candida albicans frequently causes superficial infections by invading and damaging epithelial cells, but may also cause systemic infections by...Full Text Available

International Nuclear Information System (INIS)

Point defect injection studies are performed to investigate how fluorine implantation influences the diffusion of boron marker layers in both the vacancy-rich and interstitial-rich regions of the fluorine damage profile. A 185 keV, 2.3x10"1"5 cm"-"2 F"+ implant is made into silicon samples containing multiple boron marker layers and rapid thermal annealing is performed at 1000 deg. C for times of 15-120 s. The boron and fluorine profiles are characterized by secondary ion mass spectroscopy and the defect structures by transmission electron microscopy (TEM). Fluorine implanted samples surprisingly show less boron diffusion under interstitial injection than those under inert anneal. This effect is particularly noticeable for boron marker layers located in the interstitial-rich region of the fluorine damage profile and for short anneal times (15 s). TEM images show a band of dislocation loops around the range of the fluorine ...

Science.gov (United States)

Ionizing radiation is a standard treatment for various human solid tumors. However, several clinical studies showed that a significant proportion of patients undergoing radiotherapy for hepatocellular carcinoma (HCC) develop intrahepatic and extrahepatic metastasis. Understanding of radiation-induced cancer cell invasiveness and behavior is essential and of great important for developing suitable treatment strategies to contain cancer spread. Therefore, in this study we evaluated the effectiveness of using swept source optical coherence tomography (SS-OCT) to monitor the enhancement of HCC cell invasiveness by radiation. SS-OCT images were acquired and recorded to obtain three-dimensional data sets per four hours in 48 hours after irradiating HepG2 cells with 7.5 Gy. The cell migration behavior in three-dimensional tissue models was quantified from images of ...