The Effect of Various Waste Materials' Contents on the Attenuation Level of Anti-Radiation Shielding Concrete.

Science.gov (United States)

Azeez, Ali Basheer; Mohammed, Kahtan S; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Sandu, Andrei Victor; Razak, Rafiza Abdul

2013-10-23

Samples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137 Cs and ⁶⁰Co radioactive elements with photon energies of 0.662 MeV for 137 Cs and two energy levels of 1.17 and 1.33 MeV for the ⁶⁰Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10 -3 for 137 Cs and 0.92 ± 1.57 × 10 -3 for ⁶⁰Co. Substantial improvement in attenuation performance by 20%-25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%-30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities.

Study on aerosol optical properties and radiative effect in cloudy weather in the Guangzhou region

Energy Technology Data Exchange (ETDEWEB)

Deng, Tao, E-mail: tdeng@grmc.gov.cn [Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, China Meteorological Administration, Guangzhou 510080 (China); Deng, XueJiao; Li, Fei [Institute of Tropical and Marine Meteorology/Guangdong Provincial Key Laboratory of Regional Numerical Weather Prediction, China Meteorological Administration, Guangzhou 510080 (China); Wang, ShiQiang [Zhuhai Meteorological Administration, Zhuhai 519000 (China); Wang, Gang [Haizhu Meteorological Administration, Guangzhou, 510000 (China)

2016-10-15

Currently, Guangzhou region was facing the problem of severe air pollution. Large amount of aerosols in the polluted air dramatically attenuated solar radiation. This study investigated the vertical optical properties of aerosols and inverted the height of boundary layer in the Guangzhou region using the lidar. Simultaneously, evaluated the impact of different types of clouds on aerosol radiation effects using the SBDART. The results showed that the height of the boundary layer and the surface visibility changed consistently, the average height of the boundary layer on the hazy days was only 61% of that on clear days. At the height of 2 km or lower, the aerosol extinction coefficient profile distribution decreased linearly along with height on clear days, but the haze days saw an exponential decrease. When there was haze, the changing of heating rate of atmosphere caused by the aerosol decreased from 3.72 K/d to 0.9 K/d below the height of 2 km, and the attenuation of net radiation flux at the ground surface was 97.7 W/m{sup 2}, and the attenuation amplitude was 11.4%; when there were high clouds, the attenuation was 125.2 W/m{sup 2} and the attenuation amplitude was 14.6%; where there were medium cloud, the attenuation was 286.4 W/m{sup 2} and the attenuation amplitude was 33.4%. Aerosol affected mainly shortwave radiation, and affected long wave radiation very slightly. - Highlights: • Large amount of aerosols dramatically attenuated solar radiation in Guangzhou region. • Investigated the aerosol extinction coefficient profile distribution and inverted the height of boundary layer using the lidar • Evaluated the impact of different types of clouds on aerosol radiation effects.

Effect of Different Concrete Grade on Radiation Linear Attenuation Coefficient (μ)

International Nuclear Information System (INIS)

Noor Azreen Masenwat; Mohammad Shahrizan Samsu; Mohamad Pauzi Ismail; Suhairy Sani; Ismail Mustapha; Nasharuddin Isa; Mohamad Haniza Mahmud

2014-01-01

In calculating the quantity of absorption of radiation and its relationship with the thickness of a material, linear attenuation coefficient (μ) of the material is one of the parameters to be taken into account. For normal concrete, the (μ) varies depending on the type of radiation used, 0.105 cm -1 for Co-60 and 0.123 cm -1 for Cs-137. Value (μ) is used in the calculation of the radiation absorption for concrete material does not take into account factors such concrete grades. In this research, concrete with different grades (Grade 15, Grade 20, Grade 25, Grade 30, Grade 35, Grade 40) are designed and manufactured with reference to the mixing method described in British Standard. Then, the linear attenuation (μ) for each grade are measured using the radiation from the source Co-60 and Cs-137 sources. This paper describes and discusses the impact of differences in concrete grade of linear attenuation (μ) for Co-60 source/ source Cs-137 and its relationship with the compressive strength. (author)

Attenuated UV Radiation Alters Volatile Profile in Cabernet Sauvignon Grapes under Field Conditions.

Science.gov (United States)

Liu, Di; Gao, Yuan; Li, Xiao-Xi; Li, Zheng; Pan, Qiu-Hong

2015-09-17

This study aimed to explore the effect of attenuated UV radiation around grape clusters on the volatile profile of Cabernet Sauvignon grapes (Vitis vinifera L. cv.) under field conditions. Grape bunches were wrapped with two types of polyester films that cut off 89% (film A) and 99% (film B) invisible sunlight of less than 380 nm wavelength, respectively. Solar UV radiation reaching the grape berry surface was largely attenuated, and an increase in the concentrations of amino acid-derived benzenoid volatiles and fatty acid-derived esters was observed in the ripening grapes. Meanwhile, the attenuated UV radiation significantly reduced the concentrations of fatty acid-derived aldehydes and alcohols and isoprenoid-derived norisoprenoids. No significant impact was observed for terpenes. In most case, these positive or negative effects were stage-dependent. Reducing UV radiation from the onset of veraison to grape harvest, compared to the other stages, caused a larger alteration in the grape volatile profile. Partial Least Square Discriminant Analysis (PLS-DA) revealed that (E)-2-hexenal, 4-methyl benzaldehyde, 2-butoxyethyl acetate, (E)-2-heptenal, styrene, α-phenylethanol, and (Z)-3-hexen-1-ol acetate were affected most significantly by the attenuated UV radiation.

Attenuated UV Radiation Alters Volatile Profile in Cabernet Sauvignon Grapes under Field Conditions

Directory of Open Access Journals (Sweden)

Di Liu

2015-09-01

Full Text Available This study aimed to explore the effect of attenuated UV radiation around grape clusters on the volatile profile of Cabernet Sauvignon grapes (Vitis vinifera L. cv. under field conditions. Grape bunches were wrapped with two types of polyester films that cut off 89% (film A and 99% (film B invisible sunlight of less than 380 nm wavelength, respectively. Solar UV radiation reaching the grape berry surface was largely attenuated, and an increase in the concentrations of amino acid-derived benzenoid volatiles and fatty acid-derived esters was observed in the ripening grapes. Meanwhile, the attenuated UV radiation significantly reduced the concentrations of fatty acid-derived aldehydes and alcohols and isoprenoid-derived norisoprenoids. No significant impact was observed for terpenes. In most case, these positive or negative effects were stage-dependent. Reducing UV radiation from the onset of veraison to grape harvest, compared to the other stages, caused a larger alteration in the grape volatile profile. Partial Least Square Discriminant Analysis (PLS-DA revealed that (E-2-hexenal, 4-methyl benzaldehyde, 2-butoxyethyl acetate, (E-2-heptenal, styrene, α-phenylethanol, and (Z-3-hexen-1-ol acetate were affected most significantly by the attenuated UV radiation.

Gamma radiation shielding and optical properties measurements of zinc bismuth borate glasses

International Nuclear Information System (INIS)

Yasaka, P.; Pattanaboonmee, N.; Kim, H.J.; Limkitjaroenporn, P.; Kaewkhao, J.

2014-01-01

Highlights: • 10ZnO:xBi 2 O 3 :(90−x)B 2 O 3 , (ZBB) glasses were prepared. • Radiation shielding and optical properties were investigated. • Higher 25 mol% of Bi 2 O 3 show better shielding property compared with concretes. • ZBB glasses can develop as a Pb-free radiation shielding material. - Abstract: In this work, the zinc bismuth borate (ZBB) glasses of the composition 10ZnO:xBi 2 O 3 :(90−x)B 2 O 3 (where x = 15, 20, 25 and 30 mol%) were prepared by the melt quenching technique. Their radiation shielding and optical properties were investigated and compared with theoretical calculations. The mass attenuation coefficients of ZBB glasses have been measured at different energies obtained from a Compton scattering technique. The results show a decrease of the mass attenuation coefficient, effective atomic number and effective electron density values with increasing of gamma-ray energies; and good agreements between experimental and theoretical values. The glass samples with Bi 2 O 3 concentrations higher than 25 mol% (25 and 30 mol%) were observed with lower mean free path (MFP) values than all the standard shielding concretes studied. These results are indications that the ZBB glasses in the present study may be developed as a lead-free radiation shielding material in the investigated energy range

Attenuation characteristics of materials used in radiation protection as radiation shielding

International Nuclear Information System (INIS)

Almeida Junior, Airton T.; Araujo, F.G.S.; Nogueira, M.S.; Santos, M.A.P.

2013-01-01

Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60 Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness.Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. In this work, ten plates of crystal glass, with dimensions of 20cm x 20cm and range of thicknesses from 0.5 to 2.0 cm, and barite concrete were irradiated with potential constants of 60kV, 80kV, 110kV, 150kV and gamma radiation of 60 Co. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness. (author)

Study of radioactivity and radiation attenuation of a new heavy weight concrete

International Nuclear Information System (INIS)

Ramadan, A.B.; Fouda, S.; EL-Mongy, S.; Hodhod, O.; Yousef, M.

2005-01-01

The present study is concerned with studying the radioactivity levels and efficiency of proposed heavy weight concrete as a shielding material for low and intermediate level radioactive wastes. Effect of elevated temperatures on radiation attenuation characteristics of proposed materials was also studied. Three types of local natural aggregates (iron ores) namely magnetite, limonite and hematite have been prepared, analyzed for their radioactivity and tested to determine their suitability for the manufacture of heavy weight concrete, which can be used for shielding. Hematite was excluded and two types of concrete have been prepared by using magnetite and limonite. The gamma spectrometry and neutron activation have been used to determine both uranium and thorium contents in the investigated materials. The results obtained by the two methods showed that uranium and thorium were within the acceptable low levels. It was observed that the two types of concrete have good attenuation properties

The Effect of Various Waste Materials’ Contents on the Attenuation Level of Anti-Radiation Shielding Concrete

Science.gov (United States)

Azeez, Ali Basheer; Mohammed, Kahtan S.; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Sandu, Andrei Victor; Razak, Rafiza Abdul

2013-01-01

Samples of concrete contain various waste materials, such as iron particulates, steel balls of used ball bearings and slags from steel industry were assessed for their anti-radiation attenuation coefficient properties. The attenuation measurements were performed using gamma spectrometer of NaI (Tl) detector. The utilized radiation sources comprised 137Cs and 60Co radioactive elements with photon energies of 0.662 MeV for 137Cs and two energy levels of 1.17 and 1.33 MeV for the 60Co. Likewise the mean free paths for the tested samples were obtained. The aim of this work is to investigate the effect of the waste loading rates and the particulate dispersive manner within the concrete matrix on the attenuation coefficients. The maximum linear attenuation coefficient (μ) was attained for concrete incorporates iron filling wastes of 30 wt %. They were of 1.12 ± 1.31×10−3 for 137Cs and 0.92 ± 1.57 × 10−3 for 60Co. Substantial improvement in attenuation performance by 20%–25% was achieved for concrete samples incorporate iron fillings as opposed to that of steel ball samples at different (5%–30%) loading rates. The steel balls and the steel slags gave much inferior values. The microstructure, concrete-metal composite density, the homogeneity and particulate dispersion were examined and evaluated using different metallographic, microscopic and measurement facilities. PMID:28788363

Effective radiation attenuation calibration for breast density: compression thickness influences and correction

Directory of Open Access Journals (Sweden)

Thomas Jerry A

2010-11-01

Full Text Available Abstract Background Calibrating mammograms to produce a standardized breast density measurement for breast cancer risk analysis requires an accurate spatial measure of the compressed breast thickness. Thickness inaccuracies due to the nominal system readout value and compression paddle orientation induce unacceptable errors in the calibration. Method A thickness correction was developed and evaluated using a fully specified two-component surrogate breast model. A previously developed calibration approach based on effective radiation attenuation coefficient measurements was used in the analysis. Water and oil were used to construct phantoms to replicate the deformable properties of the breast. Phantoms consisting of measured proportions of water and oil were used to estimate calibration errors without correction, evaluate the thickness correction, and investigate the reproducibility of the various calibration representations under compression thickness variations. Results The average thickness uncertainty due to compression paddle warp was characterized to within 0.5 mm. The relative calibration error was reduced to 7% from 48-68% with the correction. The normalized effective radiation attenuation coefficient (planar representation was reproducible under intra-sample compression thickness variations compared with calibrated volume measures. Conclusion Incorporating this thickness correction into the rigid breast tissue equivalent calibration method should improve the calibration accuracy of mammograms for risk assessments using the reproducible planar calibration measure.

Attenuation of gamma radiation in concrete shields

International Nuclear Information System (INIS)

Azevedo e Souza, A.C. de.

1978-12-01

The attenuation characteristics of γ radiation in concrete layers considering their mechanical resistence and densities were determined. A 137 Cs source was used in a 'good geometry' arrangement to eliminate the effects of the buildup factor. The ordinary and the heavy concrete were irradiated and for the latter it was used as additives iron ore and Fe 2 O 3 pellets in various grain sizes. The detection system consisted of a 2' x 2' NaI (Tl) crystal coupled to a photomultiplier tube and the associated electronic equipment. FORTRAN programs were used for determining the absorption coefficients and the attenuation factors. These programs calculate photopeak areas eliminating all contributions due to Compton effect and background. (Author) [pt

Influence of tube voltage on CT attenuation, radiation dose, and image quality: phantom study

International Nuclear Information System (INIS)

Li Fengtan; Li Dong; Zhang Yunting

2013-01-01

Objective: To assess the influence of tube current and tube voltage on the CT attenuation, radiation dose, and image quality. Methods: A total of 113 saline solutions with decreasing dilution of contrast medium (370 mg I/ml) was produced. MDCT scan was performed with 15 series of different settings of tube current and tube voltage. CT attenuations with 15 series of different settings were all measured, and influence of tube current and tube voltage on CT attenuations was analyzed. CT dose index (CTDIvol) was recorded. The CT attenuations with different tube voltage and current were compared with one-way ANOVA and Kruskal-Wallis rank sum test. The correlation of CT attenuation with different tube voltage and the influence of tube voltage and current on radiation dose and image quality were tested by correlation analysis. Results: Tube current (250, 200, 150, 100, and 50 mA) had no significant effect on CT attenuation (F = 0.001, 0.008, 0.075, P > 0.05), while tube voltage (120, 100, and 80 kV) had significant effect (H = 17.906, 17.906, 13.527, 20.124, 23.563, P < 0.05). The correlation between CT attenuation and tube voltage was determined with equation: CT attenuatio N_1_0_0 _k_V = 1.561 × CT attenuatio N_1_2_0 _k_v + 4.0818, CT attenuatio N_8_0 _k_v = 1.2131 × CT attenuatio N_1_2_0 _k_v + 0.9283. The influence of tube voltage on radiation dose and image quality was also analyzed, and equations were also obtained: N_1_2_0 -k_v = -5.9771 Ln (D_1_2_0 kv) + 25.412, N_1_0_0 _k_v = -10.544 Ln (D_1_0_0 _k_v) + 36.262, N_8_0 _k_v = -25.326 Ln (D_8_0 _k_v) + 62.816. According to the results of relationship among CT attenuation, radiation dose, and image quality, lower tube voltage with higher tube current can reduce the radiation dose. Conclusions: Lower tube voltage can reduce the radiation dose. However, CT attenuation was influenced, and correction should be done with the equations. (authors)

Measurement of radiation shielding properties of polymer composites by using HPGe detector

International Nuclear Information System (INIS)

Gupta, Anil; Pillay, H.C.M.; Kale, P.K.; Datta, D.; Suman, S.K.; Gover, V.

2014-01-01

Lead is the most common radiation shield and its composite with polymers can be used as flexible radiation shields for different applications. However, lead is very hazardous and has been found to be associated with neurological disorders, kidney failure and hematotoxicity. Lead free radiation shield material has been developed by synthesizing radiation cross linked PDMS/Bi 2 O 3 polymer composites. In order to have a lead free radiation shield the relevant shielding properties such as linear attenuation, half value thickness (HVT) and tenth value thickness (TVT) have been measured by using HPGe detector. The present study describes the methodology of measurement of the shielding properties of the lead free shield material. In the measurement gamma energies such as 59.537 keV ( 241 Am), 122.061 keV and 136.474 keV ( 57 Co) are taken into consideration

Lovastatin attenuates ionizing radiation-induced normal tissue damage in vivo

International Nuclear Information System (INIS)

Ostrau, Christian; Huelsenbeck, Johannes; Herzog, Melanie; Schad, Arno; Torzewski, Michael; Lackner, Karl J.; Fritz, Gerhard

2009-01-01

Background and purpose: HMG-CoA-reductase inhibitors (statins) are widely used lipid-lowering drugs. Moreover, they have pleiotropic effects on cellular stress responses, proliferation and apoptosis in vitro. Here, we investigated whether lovastatin attenuates acute and subchronic ionizing radiation-induced normal tissue toxicity in vivo. Materials and methods: Four hours to 24 h after total body irradiation (6 Gy) of Balb/c mice, acute pro-inflammatory and pro-fibrotic responses were analyzed. To comprise subchronic radiation toxicity, mice were irradiated twice with 2.5 Gy and analyses were performed 3 weeks after the first radiation treatment. Molecular markers of inflammation and fibrosis as well as organ toxicities were measured. Results: Lovastatin attenuated IR-induced activation of NF-κB, mRNA expression of cell adhesion molecules and mRNA expression of pro-inflammatory and pro-fibrotic marker genes (i.e. TNFα, IL-6, TGFβ, CTGF, and type I and type III collagen) in a tissue- and time-dependent manner. γH2AX phosphorylation stimulated by IR was not affected by lovastatin, indicating that the statin has no major impact on the induction of DNA damage in vivo. Radiation-induced thrombopenia was significantly alleviated by lovastatin. Conclusions: Lovastatin inhibits both acute and subchronic IR-induced pro-inflammatory and pro-fibrotic responses and cell death in normal tissue in vivo. Therefore, lovastatin might be useful for selectively attenuating acute and subchronic normal tissue damage caused by radiotherapy.

Nano lead oxide and epdm composite for development of polymer based radiation shielding material: Gamma irradiation and attenuation tests

Science.gov (United States)

Özdemir, T.; Güngör, A.; Akbay, I. K.; Uzun, H.; Babucçuoglu, Y.

2018-03-01

It is important to have a shielding material that is not easily breaking in order to have a robust product that guarantee the radiation protection of the patients and radiation workers especially during the medical exposure. In this study, nano sized lead oxide (PbO) particles were used, for the first time, to obtain an elastomeric composite material in which lead oxide nanoparticles, after the surface modification with silane binding agent, was used as functional material for radiation shielding. In addition, the composite material including 1%, 5%, 10%, 15% and 20% weight percent nano sized lead oxide was irradiated with doses of 81, 100 and 120 kGy up to an irradiation period of 248 days in a gamma ray source with an initial dose rate of 21.1 Gy/h. Mechanical, thermal properties of the irradiated materials were investigated using DSC, DMA, TGA and tensile testing and modifications in thermal and mechanical properties of the nano lead oxide containing composite material via gamma irradiation were reported. Moreover, effect of bismuth-III oxide addition on radiation attenuation of the composite material was investigated. Nano lead oxide and bismuth-III oxide particles were mixed with different weight ratios. Attenuation tests have been conducted to determine lead equivalent values for the developed composite material. Lead equivalent thickness values from 0.07 to 0.65 (2-6 mm sample thickness) were obtained.

Transport and attenuation of radiations

CERN Document Server

Nimal, J C

2003-01-01

This article treats of the calculation methods used for the dimensioning of the protections against radiations. The method consists in determining for a given point the flux of particles coming from a source at a given time. A strong attenuation (of about some few mu Sv.h sup - sup 1) is in general expected between the source and the areas accessible to the personnel or the public. The calculation has to take into account a huge number of radiation-matter interactions and to solve the integral-differential transport equation which links the particles flux to the source. Several methods exist from the simplified physical model with numerical developments to the more or less precise resolution of the transport equation. These methods allows also the calculation of the uncertainties of equivalent dose rates, heat sources, structure damages using the data covariances (efficient cross-sections, modeling, etc..): 1 - transport equation; 2 - Monte-Carlo method; 3 - semi-numerical methods S sub N; 4 - methods based o...

Polymer composites with carbon nanotube for application of radiation attenuator in medical procedures

Energy Technology Data Exchange (ETDEWEB)

Fontainha, C.C.P.; Nunes, M.; Rosas, V.A., E-mail: crissia@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Furtado, C.A.; Faria, L.O. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

Medical radiology offers great benefit to patients, however, the radiation contributes for the workers and individuals exposure, significantly increasing dose to population. New attenuators materials have been widely investigated for radiation shielding to apply in medical procedures. Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. In this work, composites were produced for radiation attenuation in radiodiagnostic imaging procedures. Two types of polymer matrices, polyvinylidene fluoride, PVDF, and its copolymer, poly(vinylidene-trifluorylene fluoride), P(VDF-TrFE), were filled bismuth oxide nanoparticles. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. The composites were characterized by differential heat flow scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dispersive energy X-ray spectrometry (EDS) for thermal analysis. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The samples present a good dispersion of the attenuator metal and the nanotube carbon. On the other hand, composites with PVDF matrix lost their plasticity, stiffening their structure, becoming brittle, even using the same methodology of synthesis. The P(VDF-Trfe) matrix showed better maleability than PVDF matrix. The cheaptube dispersion in the P(VDF-Trfe) matrix presented better than the 3100 carbon nanotubes. The attenuation for 8.047 keV monoenergetic photons was about 90% to 100 μm thickness for all composites. (author)

Polymer composites with carbon nanotube for application of radiation attenuator in medical procedures

International Nuclear Information System (INIS)

Fontainha, C.C.P.; Nunes, M.; Rosas, V.A.

2017-01-01

Medical radiology offers great benefit to patients, however, the radiation contributes for the workers and individuals exposure, significantly increasing dose to population. New attenuators materials have been widely investigated for radiation shielding to apply in medical procedures. Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. In this work, composites were produced for radiation attenuation in radiodiagnostic imaging procedures. Two types of polymer matrices, polyvinylidene fluoride, PVDF, and its copolymer, poly(vinylidene-trifluorylene fluoride), P(VDF-TrFE), were filled bismuth oxide nanoparticles. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. The composites were characterized by differential heat flow scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dispersive energy X-ray spectrometry (EDS) for thermal analysis. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The samples present a good dispersion of the attenuator metal and the nanotube carbon. On the other hand, composites with PVDF matrix lost their plasticity, stiffening their structure, becoming brittle, even using the same methodology of synthesis. The P(VDF-Trfe) matrix showed better maleability than PVDF matrix. The cheaptube dispersion in the P(VDF-Trfe) matrix presented better than the 3100 carbon nanotubes. The attenuation for 8.047 keV monoenergetic photons was about 90% to 100 μm thickness for all composites. (author)

Preparation of polymers suitable for radiation shielding and studying its properties (polyester composites with heavy metals salts)

International Nuclear Information System (INIS)

Kharita, M. H.; Al-Ajji, Z.; Yousef, S.

2010-12-01

Four composites were prepared in this work, based on polyester and heavy metals oxides and salts. The attenuation properties, as well as mechanical properties were studied, and the chemical stability was evaluated. It has been shown, that these composites can be used in radiation shielding for X-rays successfully, and the exact composition of these composites can be optimized according to the radiation energy to prepare the lightest possible shield. (author)

Snowpack snow water equivalent measurement using the attenuation of cosmic gamma radiation

International Nuclear Information System (INIS)

Osterhuber, R.; Condreva, K.

1998-01-01

Incoming, background cosmic radiation constantly fluxes through the earth's atmosphere. The high energy gamma portion of this radiation penetrates many terrestrial objects, including the winter snowpack. The attenuation of this radiation is exponentially related to the mass of the medium through which it penetrates. For the past three winters, a device measuring cosmic gamma radiation--and its attenuation through snow--has been installed at the Central Sierra Snow Laboratory, near Donner Pass, California. This gamma sensor, measuring energy levels between 5 and 15 MeV, has proved to be an accurate, reliable, non-invasive, non-mechanical instrument with which to measure the total snow water equivalent of a snowpack. This paper analyzes three winters' worth of data and discusses the physics and practical application of the sensor for the collection of snow water equivalent data from a remote location

Performance of composites made with polymers of silicone rubber and waste of lead on the properties of attenuation

International Nuclear Information System (INIS)

Barros, Frieda S.; Paredes, Ramon S.C.

2009-01-01

All facilities and personnel protection equipment which use ionizing radiation need protection. Based on this statement, several researchers have aimed their projects searching for new materials that present good behavior facing the attenuation properties. This research aims at the development of a composite by using the silicon rubber associated to the residue of lead in powder, obtained via the recycling of components of lead from automobile batteries. In this work , were checked the morphological physical - chemical properties of the materials isolated and associated, the calorimetrical properties of the performance of the composite related to the attenuation for X-Rays and gamma, through experimental rehearsals and computational simulation. For mixtures with 40% of lead residue, referential value in mass, favorable results were obtained about armor. In this way, it was allied the good performance of the composite with a reduction of an environmental passive to the process of recycling lead. (author)

Determination of attenuation properties of massive ceramic bricks cladded with mortars containing barite used as protective barrier for radiodiagnostic rooms

International Nuclear Information System (INIS)

Barros, Frieda S.; Schelin, Hugo R.; Tilly Junior, Joao G.; Costa, Paulo R.; Nersissian, Denise Y.; Pereira, Marco A.G.

2001-01-01

The purpose of this work is to determine the properties of attenuation of the walls built with massive ceramic bricks to be used as protection barriers in environments of Medicine and Dentistry, when submitted to X-ray diagnosis. Massive ceramic bricks are used thoroughly in constructions as a calking element. The properties of attenuation of these materials were obtained starting from the application of the model of Archer to a group of attenuation curves with wide beams generated in the tensions of 70, 80, 100, 120, 140 and 150 kVp. A radiological equipment of constant potential was used in the Laboratory of IEE/USP, two cameras of ionization of 6cm 3 , coupled to two radiation monitors. The results show that for a tension of 100kVp, the thickness of 10cm of wall made with massive ceramic bricks corresponds to 1mm of lead. (author)

Indomethacin attenuation of radiation-induced hyperthermia does not modify radiation-induced motor hypoactivity

Energy Technology Data Exchange (ETDEWEB)

Ferguson, J.L.; Kandasamy, S.B.; Harris, A.H.; Davis, H.D.; Landauer, M.R. [Armed Forces Radiobiology Research Inst., Bethesda, MD (United States)

1996-09-01

Exposure of rats to 5-10 Gy of ionizing radiation produces hyperthermia and reduces motor activity. Previous studies suggested that radiation-induced hyperthermia results from a relatively direct action on the brain and is mediated by prostaglandins. To test the hypothesis that hypoactivity may be, in part, a thermoregulatory response to this elevation in body temperature, adult male rats were given indomethacin (0.0, 0.5, 1.0, and 3.0 mg/kg, intraperitoneally), a blocker of prostaglandin synthesis, and were either irradiated (LINAC 18.6 MeV (nominal) high-energy electrons, 10 Gy at 10 Gy/min, 2.8 {mu}sec pulses at 2 Hz) or sham-irradiated. The locomotor activity of all rats was then measured for 30 min in a photocell monitor for distance traveled and number of vertical movements. Rectal temperatures of irradiated rats administered vehicle only were elevated by 0.9{+-}0.2degC at the beginning and the end of the activity session. Although indomethacin, at the two higher doses tested, attenuated the hyperthermia in irradiated rats by 52-75%, it did not attenuate radiation-induced reductions in motor activity. These results indicate that motor hypoactivity after exposure to 10 Gy of high-energy electrons is not due to elevated body temperature or to the increased synthesis of prostaglandins. (author)

Indomethacin attenuation of radiation-induced hyperthermia does not modify radiation-induced motor hypoactivity

International Nuclear Information System (INIS)

Ferguson, J.L.; Kandasamy, S.B.; Harris, A.H.; Davis, H.D.; Landauer, M.R.

1996-01-01

Exposure of rats to 5-10 Gy of ionizing radiation produces hyperthermia and reduces motor activity. Previous studies suggested that radiation-induced hyperthermia results from a relatively direct action on the brain and is mediated by prostaglandins. To test the hypothesis that hypoactivity may be, in part, a thermoregulatory response to this elevation in body temperature, adult male rats were given indomethacin (0.0, 0.5, 1.0, and 3.0 mg/kg, intraperitoneally), a blocker of prostaglandin synthesis, and were either irradiated (LINAC 18.6 MeV (nominal) high-energy electrons, 10 Gy at 10 Gy/min, 2.8 μsec pulses at 2 Hz) or sham-irradiated. The locomotor activity of all rats was then measured for 30 min in a photocell monitor for distance traveled and number of vertical movements. Rectal temperatures of irradiated rats administered vehicle only were elevated by 0.9±0.2degC at the beginning and the end of the activity session. Although indomethacin, at the two higher doses tested, attenuated the hyperthermia in irradiated rats by 52-75%, it did not attenuate radiation-induced reductions in motor activity. These results indicate that motor hypoactivity after exposure to 10 Gy of high-energy electrons is not due to elevated body temperature or to the increased synthesis of prostaglandins. (author)

Radiation shielding properties of a novel cement–basalt mixture for nuclear energy applications

Energy Technology Data Exchange (ETDEWEB)

Ipbüker, Cagatay; Nulk, Helena; Gulik, Volodymyr [University of Tartu, Institute of Physics (Estonia); Biland, Alex [HHK Technologies, Houston (United States); Tkaczyk, Alan Henry, E-mail: alan@ut.ee [University of Tartu, Institute of Physics (Estonia)

2015-04-01

Highlights: • Basalt fiber is a relatively cheap material that can be used as reinforcement. • Gamma-ray attenuation remains relatively stable with addition of basalt fiber. • Neutron attenuation remains relatively stable with addition of basalt fiber. • Cement–basalt mixture has a good potential for use in nuclear energy applications. - Abstract: The radiation shielding properties of a new proposed building material, a novel cement–basalt fiber mixture (CBM), are investigated. The authors analyze the possibility of this material to be a viable substitute to outgoing materials in nuclear energy applications, which will lead to a further sustained development of nuclear energy in the future. This computational study involves four types of concrete with various amounts of basalt fiber in them. The gamma-ray shielding characteristics of proposed CBM material are investigated with the help of WinXCom program, whereas the neutron shielding characteristics are computed by the Serpent code. For gamma-ray shielding, we find that the attenuation coefficients of concretes with basalt fibers are not notably influenced by the addition of fibers. For neutron shielding, additional basalt fiber in mixture presents negligible effect on neutron radiation shielding. With respect to radiation shielding, it can be concluded that basalt fibers have good potential as an addition to heavyweight concrete for nuclear energy applications.

Radiation shielding properties of a novel cement–basalt mixture for nuclear energy applications

International Nuclear Information System (INIS)

Ipbüker, Cagatay; Nulk, Helena; Gulik, Volodymyr; Biland, Alex; Tkaczyk, Alan Henry

2015-01-01

Highlights: • Basalt fiber is a relatively cheap material that can be used as reinforcement. • Gamma-ray attenuation remains relatively stable with addition of basalt fiber. • Neutron attenuation remains relatively stable with addition of basalt fiber. • Cement–basalt mixture has a good potential for use in nuclear energy applications. - Abstract: The radiation shielding properties of a new proposed building material, a novel cement–basalt fiber mixture (CBM), are investigated. The authors analyze the possibility of this material to be a viable substitute to outgoing materials in nuclear energy applications, which will lead to a further sustained development of nuclear energy in the future. This computational study involves four types of concrete with various amounts of basalt fiber in them. The gamma-ray shielding characteristics of proposed CBM material are investigated with the help of WinXCom program, whereas the neutron shielding characteristics are computed by the Serpent code. For gamma-ray shielding, we find that the attenuation coefficients of concretes with basalt fibers are not notably influenced by the addition of fibers. For neutron shielding, additional basalt fiber in mixture presents negligible effect on neutron radiation shielding. With respect to radiation shielding, it can be concluded that basalt fibers have good potential as an addition to heavyweight concrete for nuclear energy applications

Result of radiation therapy of sino-nasal cancers using partial attenuation filter

Energy Technology Data Exchange (ETDEWEB)

Kim, Jin Hee; Kim, Ok Bae; Choi, Tae Jin [Keimyung University College of Medicine, Daegu (Korea, Republic of)

2007-06-15

This study was to evaluate the survival and pattern of failure after radiation therapy of sino-nasal cancer using partial attenuation filer and wedged beams and to help radiotherapy planning of sino-nasal cancer. Between February 1992 and March 2003, 17 patients with sino-nasal cancers underwent radiation therapy using partial attenuation filter at Dongsan Medical Center, Keimyung university. There were 9 male and 8 female patients. Patients' age ranged from 40 to 75 years (median 59 years). There were 10 patients of maxillary sinus cancer, 7 patients of nasal cancer. The histologic type was squamous cell carcinoma in 11, adenoid cystic carcinoma in 4 and olfactory neuroblastoma in 2. The distribution of clinical stage by the AJCC system was 3 for stage II, 7 for III and 6 for IV. The five patients were treated with radiation alone and 12 patients were treated with surgery and postoperative radiation therapy. The range of total radiation dose delivered to the primary tumor was from 44 to 76 Gy (median 60 Gy). The follow-up period ranged from 3 to 173 months with median of 78 months. The overall 2 year survival rate and disease free survival rate was 76.4%. The 5 year and 10 year survival rate were 76.4% and 45.6% and the 5 year and 10 year disease free survival rate was 70.6%. The 5 year disease free survival rate by treatment modality was 91.6% for postoperative radiation group and 20% for radiation alone group, statistical significance was found by treatment modality ({rho} = 0.006). There were no differences in survival by pathology and stage. There were local failure in 5 patients (29%) but no distant failure and no severe complication required surgical intervention. Radiation therapy of sino-nasal cancer using partial attenuation filter was safe and effective. Combined modality with conservative surgery and radiation therapy was more advisable to achieve loco-regional control in sino-nasal cancer. Also we considered high precision radiation therapy with

Nicaraven attenuates radiation-induced injury in hematopoietic stem/progenitor cells in mice.

Directory of Open Access Journals (Sweden)

Miho Kawakatsu

Full Text Available Nicaraven, a chemically synthesized hydroxyl radical-specific scavenger, has been demonstrated to protect against ischemia-reperfusion injury in various organs. We investigated whether nicaraven can attenuate radiation-induced injury in hematopoietic stem/progenitor cells, which is the conmen complication of radiotherapy and one of the major causes of death in sub-acute phase after accidental exposure to high dose radiation. C57BL/6 mice were exposed to 1 Gy γ-ray radiation daily for 5 days in succession (a total of 5 Gy, and given nicaraven or a placebo after each exposure. The mice were sacrificed 2 days after the last radiation treatment, and the protective effects and relevant mechanisms of nicaraven in hematopoietic stem/progenitor cells with radiation-induced damage were investigated by ex vivo examination. We found that post-radiation administration of nicaraven significantly increased the number, improved the colony-forming capacity, and decreased the DNA damage of hematopoietic stem/progenitor cells. The urinary levels of 8-oxo-2'-deoxyguanosine, a marker of DNA oxidation, were significantly lower in mice that were given nicaraven compared with those that received a placebo treatment, although the levels of intracellular and mitochondrial reactive oxygen species in the bone marrow cells did not differ significantly between the two groups. Interestingly, compared with the placebo treatment, the administration of nicaraven significantly decreased the levels of the inflammatory cytokines IL-6 and TNF-α in the plasma of mice. Our data suggest that nicaraven effectively diminished the effects of radiation-induced injury in hematopoietic stem/progenitor cells, which is likely associated with the anti-oxidative and anti-inflammatory properties of this compound.

Radiation Shielding Properties Comparison of Pb-Based Silicate, Borate, and Phosphate Glass Matrices

Directory of Open Access Journals (Sweden)

Suwimon Ruengsri

2014-01-01

Full Text Available Theoretical calculations of mass attenuation coefficients, partial interactions, atomic cross-section, and effective atomic numbers of PbO-based silicate, borate, and phosphate glass systems have been investigated at 662 keV. PbO-based silicate glass has been found with the highest total mass attenuation coefficient and then phosphate and borate glasses, respectively. Compton scattering has been the dominate interaction contributed to the different total attenuation coefficients in each of the glass matrices. The silicate and phosphate glass systems are more appropriate choices as lead-based radiation shielding glass than the borate glass system. Moreover, comparison of results has shown that the glasses possess better shielding properties than standard shielding concretes, suggesting a smaller size requirement in addition to transparency in the visible region.

Radiation protection clothing in X-ray diagnostics. Comparison of attenuation equivalents in narrow beam and inverse broad-beam geometry

International Nuclear Information System (INIS)

Pichler, Thomas; Schoepf, T.; Ennemoser, O.

2011-01-01

Purpose: Standard DIN EN 61 331-1 for attenuation measurements in the narrow and broad beam as well as DIN 6857-1 for the determination of shielding properties in the inverse broad-beam geometry are available for testing the attenuation of protection clothing. The attenuation measurements in the narrow beam don't consider scattered radiation and fluorescence due to the arrangement. This leads to the fact that the protective effect of lead-free materials will be misestimated when compared to lead. Therefore, the differences in attenuation equivalents, determined by both test methods for topical radiation protection aprons, were examined. Materials and Methods: The attenuations in inverse broad-beam geometry according to DIN 6857-1 and in the narrow beam according to DIN EN 61 331-1 were measured using commercially available aprons. They were made of lead, lead-reduced and lead-free materials. For determination of the attenuation equivalents, certificated lead-foils with high purity and a precise thickness of 0.1 to 1.25 mm were used. Results: The measurements in the narrow beam according to DIN EN 61 331-1 showed that nearly all aprons reach the required lead equivalent at mid-range tube voltages of 100 kV. At higher and lower tube voltages, the requirements of DIN EN 61 331-3 were largely not met. In contrast, the testing of the same aprons in inverse broad-beam geometry according to DIN 6857-1 showed that only a few aprons meet the requirements for being classified in the nominal protection class. Conclusion: The measurements suggest that testing method DIN 6857-1 has yet to prevail and that manufacturers are just beginning to develop the appropriate protective materials. (orig.)

Optimal Background Attenuation for Fielded Radiation Detection Systems

International Nuclear Information System (INIS)

Robinson, Sean M.; Kaye, William R.; Schweppe, John E.; Siciliano, Edward R.

2006-01-01

Radiation detectors are often placed in positions difficult to shield from the effects of terrestrial background. This is particularly true in the case of Radiation Portal Monitor (RPM) systems, as their wide viewing angle and outdoor installations make them susceptible to terrestrial background from the surrounding area. A low background is desired in most cases, especially when the background noise is of comparable strength to the signal of interest. The problem of shielding a generalized RPM from terrestrial background is considered. Various detector and shielding scenarios are modeled with the Monte-Carlo N Particle (MCNP) computer code. Amounts of nominal-density shielding needed to attenuate the terrestrial background to varying degrees are given, along with optimal shielding geometry to be used in areas where natural shielding is limited, and where radiation detection must occur in the presence of natural background. Common shielding solutions such as steel plating are evaluated based on the signal to noise ratio and the benefits are weighed against the incremental cost.

Study of Radiation Shielding Properties of selected Tropical Wood Species for X-rays in the 50-150 keV Range

Directory of Open Access Journals (Sweden)

S. Aggrey-Smith

2016-03-01

Full Text Available This paper compares the attenuation coefficients of 20 tropical hard wood species based on their linear and mass attenuation and half value layer (HVL properties for X-rays of energy 50–150 keV using a narrow collimated beam from a Cs-137 source. The narrow collimated beam method made corrections from multiple and small-angle scatterings of photons unnecessary. The attenuation depended on the chemical composition and densities of the wood species. The linear attenuation coefficients of wood species at 50–150 keV were highest for Pterygota macrocarpa (4.53 m−1 and lowest for Antiaris africana (1.24 m−1; the mass attenuation coefficient was highest for Triplochiton scleroxylon (17.62 m2/kg and lowest for Nesogordonia papaverifera (2.27 m2/kg.The HVL was highest for Antiaris africana (0.27 m and lowest for Pterygota macrocarpa (0.149 m. Pterygota macrocarpa of about 0.36 m thickness could serve as a more affordable radiation shielding material against secondary scatter and leakage radiations in place of lead, copper or concrete for low X-ray radiations up to 150 keV.

Mass attenuation coefficients of X-rays in different barite concrete used in radiation protection as shielding against ionizing radiation

International Nuclear Information System (INIS)

Almeida, A. T. Jr.; Nogueira, M.S.; Santos, M.A.P.; Campos, L.L.; Araújo, F. G. S.

2015-01-01

The attenuation coefficient depends on the incident photon energy and the nature of the materials. In order to minimize exposure to individuals. Barite concrete has been largely used as a shielding material in installations housing gamma radiation sources as well as X-ray generating equipment. This study was conducted to evaluate the efficacy of different mixtures of barite concrete for shielding in diagnostic X-ray rooms. The mass attenuation coefficient (μ/ρ). The mass attenuation coefficients have been measured by employing the CdTe detector model XR-100T. The distance between the source and the exposed surface of all samples was measured by SSD light indicator of machine which was 350 cm. The slope of the linear plot of the intensity transmitted versus specimen thickness would yield the attenuation coefficient. The mass attenuation coefficients (μ/ρ) were compared with the tabulations based upon the results of the XCOM program. The rectangular barite concrete blocks in different thicknesses from were used for the radiation attenuation test. The experimental values were compared with theoretical values WinXcom. The plots of the logarithm of transmitted intensity versus specimen thickness were linear for all the samples and the µ/ρ was obtained from the plots by linear regression over the 25%-2% transmission range, under good geometrical condition. There is a good agreement between theoretical and experimental values, within the 9%. In fact over the entire transmission range of 25-2% the experimental and theoretical values agree well for both the energies. (authors)

Investigation of novel composite material based on extra-heavy concrete and basalt fiber for gamma radiation protection properties

International Nuclear Information System (INIS)

Romanenko, Yi.M.; Nosovs'kij, A.V.; Gulyik, V.Yi.; Golyuk, M.Yi.

2018-01-01

The paper presents a new composite material for radiation protection based on extra-heavy concrete reinforced by basalt fiber. Basalt fiber is a new material for concrete reinforcement, which provides improved mechanical characteristics of concrete, reduces the level of microcracks and increases the durability of concrete. Within the scope of present work, the gamma-ray radiation protection properties of concrete reinforced with basalt fiber was modeled. Two types of extra-heavy concrete were used for this paper. The main gamma-ray attenuation coefficients such as mean atomic number, mean atomic mass, mean electron density, effective atomic number, effective electron density, Murty effective atomic number were analyzed with help of WinXCom software. It has been shown that the addition of basalt fiber to concrete does not impair its gamma-ray radiation shielding properties. With increasing the basalt fiber dosage in concrete, the radiation properties against gamma radiation are improved.

Effect of physical, chemical and electro-kinetic properties of pumice samples on radiation shielding properties of pumice material

International Nuclear Information System (INIS)

Tapan, Mücip; Yalçın, Zeynel; İçelli, Orhan; Kara, Hüsnü; Orak, Salim; Özvan, Ali; Depci, Tolga

2014-01-01

Highlights: • Radiation shielding properties of pumice materials are studied. • The relationship between physical, chemical and electro-kinetic properties pumice samples is identified. • The photon atomic parameters are important for the absorber peculiarity of the pumices. - Abstract: Pumice has been used in cement, concrete, brick, and ceramic industries as an additive and aggregate material. In this study, some gamma-ray photon absorption parameters such as the total mass attenuation coefficients, effective atomic number and electronic density have been investigated for six different pumice samples. Numerous values of energy related parameters from low energy (1 keV) to high energy (100 MeV) were calculated using WinXCom programme. The relationship between radiation shielding properties of the pumice samples and their physical, chemical and electro-kinetic properties was evaluated using simple regression analysis. Simple regression analysis indicated a strong correlation between photon energy absorption parameters and density and SiO 2 , Fe 2 O 3 , CaO, MgO, TiO 2 content of pumice samples in this study. It is found that photon energy absorption parameters are not related to electro-kinetic properties of pumice samples

Attenuation of radiation- and drug-induced conditioned taste aversions following area postrema lesions in the rat

International Nuclear Information System (INIS)

Rabin, B.M.; Hunt, W.A.; Lee, J.

1983-01-01

The effects of lesions of the area postrema on the acquisition of radiation- and drug-induced (histamine and lithium chloride) conditioned taste aversions were investigated. The results indicated that area postrema lesions caused a significant attenuation of the aversion produced by pairing a novel sucrose solution with radiation (100 rad) or drug injection. Further, the area postrema lesions produced a similar level of attenuation of the taste aversion in all three treatment conditions. The results are discussed in terms of the implications of this finding for defining the mechanisms by which exposure to ionizing radiation can lead to the acquisition of a conditioned taste aversion

Interlaboratory comparison of radiation-induced attenuation in optical fibers

International Nuclear Information System (INIS)

Friebele, E.J.; Lyons, P.B.; Blackburn, J.C.

1989-08-01

A comparison of the losses induced in step index multimode, graded index multimode and single mode fibers by pulsed radiation exposure has been made among 12 laboratories over a period of 5 years. The recoveries of the incremental attenuations from 10 -9 to 10 1 s are reported. Although a standard set of measurement parameters was attempted, differences between the laboratories are evident; possible origins for these are discussed. 18 refs., 18 figs., 7 tabs

Photon attenuation properties of some thorium, uranium and plutonium compounds

Energy Technology Data Exchange (ETDEWEB)

Singh, V. P.; Badiger, N. M. [Karnatak University, Department of Physics, Dharwad-580003, Karnataka (India); Vega C, H. R., E-mail: kudphyvps@rediffmail.com [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas, Zac. (Mexico)

2015-10-15

Mass attenuation coefficients, effective atomic numbers, effective electron densities for nuclear materials; thorium, uranium and plutonium compounds have been studied. The photon attenuation properties for the compounds have been investigated for partial photon interaction processes by photoelectric effect, Compton scattering and pair production. The values of these parameters have been found to change with photon energy and interaction process. The variations of mass attenuation coefficients, effective atomic number and electron density with energy are shown graphically. Moreover, results have shown that these compounds are better shielding and suggesting smaller dimensions. The study would be useful for applications of these materials for gamma ray shielding requirement. (Author)

Characteristics of liver tissue for attenuate the gamma radiation; Caracteristicas del tejido hepatico para atenuar la radiacion gamma

Energy Technology Data Exchange (ETDEWEB)

Arcos P, A.; Rodriguez N, S.; Pinedo S, A.; Amador V, P.; Chacon R, A.; Vega C, H.R. [Unidad Academica de Estudios Nucleares, Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico)

2005-07-01

It was determined the lineal attenuation coefficient of hepatic tissue before gamma radiation of a source of {sup 137} Cs. When exposing organic material before X or gamma radiation fields, part of the energy of the photons is absorbed by the material, while another part crosses it without producing any effect. The quantity of energy that is absorbed is a measure of the dose that receives the material. The three main mechanisms by means of which the gamma rays interacting with the matter are: The Photoelectric Effect, the Compton dispersion and the Even production; the sum of these three processes is translated in the attenuation coefficient of the radiation. In this work we have used hepatic tissue of bovine, as substitute of the human hepatic tissue, and we have measured the lineal attenuation coefficient for photons of 0.662 MeV. Through a series of calculations we have determined the lineal attenuation coefficient for photons from 10{sup -3} to 10{sup -5} MeV and the measured coefficient was compared with the one calculated. (Author)

The measurement of attenuation coefficients at low photon energies using fluorescent x-radiation

International Nuclear Information System (INIS)

Peaple, L.H.J.; White, D.R.

1978-03-01

A rapid and accurate method has been developed to measure low energy attenuation coefficients for materials of importance in radiation dosimetry. It employs a collimated beam of fluorescent x-rays from which the required radiation is selected by means of a high resolution germanium detector and multi-channel analyser. The method is described in detail and its accuracy and application outlined with reference to the results from nine different materials. (author)

[Radiometers performance attenuation and data correction in long-term observation of total radiation and photosynthetically active radiation in typical forest ecosystems in China].

Science.gov (United States)

Zhu, Zhi-Lin; Sun, Xiao-Min; Yu, Gui-Rui; Wen, Xue-Fa; Zhang, Yi-Ping; Han, Shi-Jie; Yan, Jun-Hua; Wang, Hui-Min

2011-11-01

Based on the total radiation and photosynthetically active radiation (PAR) observations with net radiometer (CNR1) and quantum sensor (Li-190SB) in 4 ChinaFLUX forest sites (Changbaishan, Qianyanzhou, Dinghushan, and Xishuangbanna) in 2003-2008, this paper analyzed the uncertainties and the radiometers performance changes in long-term and continuous field observation. The results showed that the 98% accuracy of the total radiation measured with CNR1 (Q(cNR1)) could satisfy the technical criterion for the sites except Xishuangbanna where the Q(CNR1) was averagely about 7% lower than Q(CM11), the radiation measured with high accuracy pyranometer CM11. For most sites, though the temperature had definite effects on the performance of CNR1, the effects were still within the allowable range of the accuracy of the instrument. Besides temperature, the seasonal fog often occurred in tropical rain forests in Xishuangbanna also had effects on the performance of CNR1. Based on the long-term variations of PAR, especially its ratio to total radiation in the 4 sites, it was found that quantum sensor (Li-190SB) had obvious performance attenuation, with the mean annual attenuation rate being about 4%. To correct the observation error caused by Li-190SB, an attempt was made to give a post-correction of the PAR observations, which could basically eliminate the quantum sensor's performance attenuation due to long-term field measurement.

Attenuation of Reactor Gamma Radiation and Fast Neutrons Through Large Single-Crystal Materials

International Nuclear Information System (INIS)

Adib, M.

2009-01-01

A generalized formula is given which, for neutron energies in the range 10-4< E< 10 eV and gamma rays with average energy 2 MeV , permits calculation of the transmission properties of several single crystal materials important for neutron scattering instrumentation. A computer program Filter was developed which permits the calculation of attenuation of gamma radiation, nuclear capture, thermal diffuse and Bragg-scattering cross-sections as a function of materials constants, temperature and neutron energy. The applicability of the deduced formula along with the code checked from the obtained agreement between the calculated and experimental neutron transmission through various single-crystals A feasibility study for use of Si, Ge, Pb, Bi and sapphire is detailed in terms of optimum crystal thickness, mosaic spread and cutting plane for efficient transmission of thermal reactor neutrons and for rejection of the accompanying fast neutrons and gamma rays.

Phase Aberration and Attenuation Effects on Acoustic Radiation Force-Based Shear Wave Generation.

Science.gov (United States)

Carrascal, Carolina Amador; Aristizabal, Sara; Greenleaf, James F; Urban, Matthew W

2016-02-01

Elasticity is measured by shear wave elasticity imaging (SWEI) methods using acoustic radiation force to create the shear waves. Phase aberration and tissue attenuation can hamper the generation of shear waves for in vivo applications. In this study, the effects of phase aberration and attenuation in ultrasound focusing for creating shear waves were explored. This includes the effects of phase shifts and amplitude attenuation on shear wave characteristics such as shear wave amplitude, shear wave speed, shear wave center frequency, and bandwidth. Two samples of swine belly tissue were used to create phase aberration and attenuation experimentally. To explore the phase aberration and attenuation effects individually, tissue experiments were complemented with ultrasound beam simulations using fast object-oriented C++ ultrasound simulator (FOCUS) and shear wave simulations using finite-element-model (FEM) analysis. The ultrasound frequency used to generate shear waves was varied from 3.0 to 4.5 MHz. Results: The measured acoustic pressure and resulting shear wave amplitude decreased approximately 40%-90% with the introduction of the tissue samples. Acoustic intensity and shear wave displacement were correlated for both tissue samples, and the resulting Pearson's correlation coefficients were 0.99 and 0.97. Analysis of shear wave generation with tissue samples (phase aberration and attenuation case), measured phase screen, (only phase aberration case), and FOCUS/FEM model (only attenuation case) showed that tissue attenuation affected the shear wave generation more than tissue aberration. Decreasing the ultrasound frequency helped maintain a focused beam for creation of shear waves in the presence of both phase aberration and attenuation.

Multiple-energy tissue-cancellation applications of a digital beam attenuator to chest radiography

International Nuclear Information System (INIS)

Dobbins, J.T. III.

1985-01-01

The digitally-formed primary beam attenuator (DBA) spatially modulates the x-ray fluence incident upon the patient to selectively attenuate regions of interest. The DBA attenuating mask is constructed from CeO 2 powder by a modified printing technique and uses image information from an initial low-dose exposure. Two tissue-cancellation imaging techniques are investigated with the DBA: (1) energy-dependent information is used to form a beam attenuator that attenuates specific tissues in the primary x-ray beam for tissue-cancelled film radiography; (2) the beam attenuator is used to improve image signal-to-noise and scattered radiation properties in traditional energy-subtraction tissue-cancellation imaging with digital detectors. The tissue-cancellation techniques in the primary x-ray beam were capable of adequately removing either soft-tissue or bone from the final compensated film radiograph when using a phantom with well defined soft-tissue and bone sections. However, when tried on an anthropomorphic chest phantom the results were adequate for cancellation of large soft tissue structures, but unsatisfactory for cancellation of bony structures such as the ribs, because of the limited spatial frequency content of the attenuating mask. The second technique (with digital detectors) showed improved uniformity of image signal-to-noise and a two-fold increase in soft-tissue nodule contrast due to improved scattered radiation properties. The tissue-cancelled images contained residual image contributions from the presence of the attenuating mask, but this residual may be correctable by future algorithms

Loss of Matrix Metalloproteinase-13 Attenuates Murine Radiation-Induced Pulmonary Fibrosis

International Nuclear Information System (INIS)

Flechsig, Paul; Hartenstein, Bettina; Teurich, Sybille; Dadrich, Monika; Hauser, Kai; Abdollahi, Amir; Groene, Hermann-Josef; Angel, Peter; Huber, Peter E.

2010-01-01

Purpose: Pulmonary fibrosis is a disorder of the lungs with limited treatment options. Matrix metalloproteinases (MMPs) constitute a family of proteases that degrade extracellular matrix with roles in fibrosis. Here we studied the role of MMP13 in a radiation-induced lung fibrosis model using a MMP13 knockout mouse. Methods and Materials: We investigated the role of MMP13 in lung fibrosis by investigating the effects of MMP13 deficiency in C57Bl/6 mice after 20-Gy thoracic irradiation (6-MV Linac). The morphologic results in histology were correlated with qualitative and quantitative results of volume computed tomography (VCT), magnetic resonance imaging (MRI), and clinical outcome. Results: We found that MMP13 deficient mice developed less pulmonary fibrosis than their wildtype counterparts, showed attenuated acute pulmonary inflammation (days after irradiation), and a reduction of inflammation during the later fibrogenic phase (5-6 months after irradiation). The reduced fibrosis in MMP13 deficient mice was evident in histology with reduced thickening of alveolar septi and reduced remodeling of the lung architecture in good correlation with reduced features of lung fibrosis in qualitative and quantitative VCT and MRI studies. The partial resistance of MMP13-deficient mice to fibrosis was associated with a tendency towards a prolonged mouse survival. Conclusions: Our data indicate that MMP13 has a role in the development of radiation-induced pulmonary fibrosis. Further, our findings suggest that MMP13 constitutes a potential drug target to attenuate radiation-induced lung fibrosis.

Attenuation and cross-attenuation in taste aversion learning in the rat: Studies with ionizing radiation, lithium chloride and ethanol

International Nuclear Information System (INIS)

Rabin, B.M.; Hunt, W.A.; Lee, J.

1988-01-01

The preexposure paradigm was utilized to evaluate the similarity of ionizing radiation, lithium chloride and ethanol as unconditioned stimuli for the acquisition of a conditioned taste aversion. Three unpaired preexposures to lithium chloride (3.0 mEq/kg, IP) blocked the acquisition of a taste aversion when a novel sucrose solution was paired with either the injection of the same dose of lithium chloride or exposure to ionizing radiation (100 rad). Similar pretreatment with radiation blocked the acquisition of a radiation-induced aversion, but had no effect on taste aversions produced by lithium chloride (3.0 or 1.5 mEq/kg). Preexposure to ethanol (4 g/kg, PO) disrupted the acquisition of an ethanol-induced taste aversion, but not radiation- or lithium chloride-induced aversions. In contrast, preexposure to either radiation or lithium chloride attenuated an ethanol-induced taste aversion in intact rats, but not in rats with lesions of the area postrema. The results are discussed in terms of relationships between these three unconditioned stimuli and in terms of implications of these results for understanding the nature of the proximal unconditioned stimulus in taste aversion learning

Mechanical and radiation shielding properties of mortars with additive fine aggregate mine waste

International Nuclear Information System (INIS)

Gallala, Wissem; Hayouni, Yousra; Gaied, Mohamed Essghaier; Fusco, Michael; Alsaied, Jasmin; Bailey, Kathryn; Bourham, Mohamed

2017-01-01

Highlights: • Effectiveness of mine waste as additive fine aggregate has been investigated. • Experimental results are verified by computationally from composition of synthesized samples. • Work focuses on shielding materials for nuclear systems including spent fuel storage and drycasks. - Abstract: Incorporation of barite-fluorspar mine waste (BFMW) as a fine aggregate additive has been investigated for its effect on the mechanical and shielding properties of cement mortar. Several mortar mixtures were prepared with different proportions of BFMW ranging from 0% to 30% as fine aggregate replacement. Cement mortar mixtures were evaluated for density, compressive and tensile strengths, and gamma ray radiation shielding. The results revealed that the mortar mixes containing 25% BFMW reaches the highest compressive strength values, which exceeded 50 MPa. Evaluation of gamma-ray attenuation was both measured by experimental tests and computationally calculated using MicroShield software package, and results have shown that using BFMW aggregates increases attenuation coefficient by about 20%. These findings have demonstrated that the mine waste can be suitably used as partial replacement aggregate to improve radiation shielding as well as to reduce the mortar and concrete costs.

Radiation shielding properties of some natural rocks in upper Egypt

International Nuclear Information System (INIS)

Abbady, A.; Ahmed, N.K.; Saied, M.H.; Uosif, M.A.; El-kamel, A.H.

1999-01-01

To support the use of some natural rocks in Upper Egypt as suitable radiation materials, the attenuation of gamma - ray through destructive and nondestructive samples of alabaster, marble and limestone have been tested in the energy range from 356 keV to 1173 keV. The attenuation coefficients of the nondestructive samples are found higher than the values of the destructive samples. The half - layer values for attenuation, and the concentration of uranium and thorium in the samples were calculated and discussed

Schistosoma mansoni: migration potential of normal and radiation attenuated parasites in naive guinea pigs

International Nuclear Information System (INIS)

Kamiya, H.; McLaren, D.J.

1987-01-01

Compressed tissue autoradiography using [75Se]selenomethionine labelled parasites has been used to investigate the migration potential of normal and radiation attenuated cercariae of Schistosoma mansoni in naive guinea pigs. By Day 14 after infection. 44% of normal parasites were detected as reduced silver foci in the liver; this value corresponded well with the number of liver parasites recovered by retrograde perfusion of the hepatic portal system on Day 42 (42% of the challenge). In contrast, cercariae subjected to 50 krad of gamma irradiation failed to migrate out of the skin. The migration capacity of 20 krad irradiated parasites was less severely affected in that about half of the challenge parasites reached the lungs, but virtually none moved to the liver. These data are discussed in relation to the kinetics of immunity induced in guinea pigs by infection or vaccination with normal or radiation attenuated parasites

Attenuation of a radiation-induced conditioned taste aversion after the development of ethanol tolerance

International Nuclear Information System (INIS)

Hunt, W.A.; Rabin, B.M.

1988-01-01

An attempt to reduce a radiation-induced conditioned taste aversion (CTA) was undertaken by rendering animals tolerant to ethanol. Ethanol tolerance, developed over 5 days, was sufficient to block a radiation-induced taste aversion, as well as an ethanol-induced CTA. Several intermittent doses of ethanol, which did not induce tolerance but removed the novelty of the conditioning stimulus, blocked an ethanol-induced CTA but not the radiation-induced CTA. A CTA induced by doses of radiation up to 500 rads was attenuated. These data suggest that radioprotection developing in association with ethanol tolerance is a result of a physiological response to the chronic presence of ethanol not to the ethanol itself

Study of 60 Co gamma radiation effects on the biochemical, biological and immunological properties of the Bothrops jararaca venom

International Nuclear Information System (INIS)

Guarnieri, M.C.

1992-01-01

Gamma radiation, by including different modifications on the toxic, enzymatic and immunological activities of proteins, could be an useful implement for detoxification of snake venoms. The present work was done to study the mechanism of action and effects of gamma rays on the Bothrops jararaca venom, determining the radiation dose that attenuates the toxic and enzymatic activities maintaining the immunological properties of venom, and also the most important free radicals on this process. The results of immuno diffusion, immunoblotting, immunoprecipitation, immunization of mice and rabbits, and neutralization tests, showed the maintenance of antigenic and immunogenic properties and decrease of neutralizing capacity of antibodies induced by 3,000 and 4,000 Gy irradiated venom. Since the immunological properties were the most radioresistant, it was possible to determine the dose of 2,000 Gy, as the ideal radiation dose in the treatment of venoms aiming the improvement of the immunization schedule to obtain bothropic antisera. (author). 164 refs, 19 tabs, 54 figs

Attenuate Eimeria Tenella parasite by gamma radiation in chicken vaccination

International Nuclear Information System (INIS)

El-atar, M.A.

1998-01-01

Mature occysts of eimeria tenella were attenuated by different doses of gamma radiation. The vitality, pathogenicity and immunogenicity of these occysts were examined by infecting one day old broiler chicks. The study revealed that the irradiated occysts lost pathogenicity by increasing radiation dose. To examine the immunogenicity of irradiated occysts, chickens were challenged 28 days post immunogenic infection. It was shown that the irradiated occycts kept their immunogenicity but this ability decreased when the irradiation dose was increased. Also, the number of vaccination doses as well as the level of irradiation were studied. Occysts irradiated with 15, 18, 20 Krad were used to vaccinate one-day old broiler chicks for one or two times, and seven-day old chicks for three times. High level of protection was observed as shown by disappeaeance of clinical signs or mortality in most vaccinated groups

A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

Energy Technology Data Exchange (ETDEWEB)

Kawaguchi, Hiroshi, E-mail: kwgc@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Hirano, Yoshiyuki, E-mail: yhirano@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yoshida, Eiji, E-mail: rush@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Kershaw, Jeff, E-mail: len@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Shiraishi, Takahiro, E-mail: tshira@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Suga, Mikio, E-mail: mikio.suga@faculty.chiba-u.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Graduate School of Engineering of Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ikoma, Yoko, E-mail: ikoma@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Obata, Takayuki, E-mail: t_obata@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Ito, Hiroshi, E-mail: hito@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Yamaya, Taiga, E-mail: taiga@nirs.go.jp [Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)

2014-01-11

Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

A proposal for PET/MRI attenuation correction with μ-values measured using a fixed-position radiation source and MRI segmentation

International Nuclear Information System (INIS)

Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Yoshida, Eiji; Kershaw, Jeff; Shiraishi, Takahiro; Suga, Mikio; Ikoma, Yoko; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

2014-01-01

Several MRI-based attenuation correction methods have been reported for PET/MRI; these methods are expected to make efficient use of high-quality anatomical MRIs and reduce the radiation dose for PET/MRI scanning. The accuracy of the attenuation map (μ-map) from an MRI depends on the accuracy of tissue segmentation and the attenuation coefficients to be assigned (μ-values). In this study, we proposed an MRI-based μ-value estimation method with a non-rotational radiation source to construct a suitable μ-map for PET/MRI. The proposed method uses an accurately segmented tissue map, the partial path length of each tissue, and detected intensities of attenuated radiation from a fixed-position (rather than a rotating) radiation source to obtain the μ-map. We estimated the partial path length from a virtual blank scan of fixed-point radiation with the same scanner geometry using the known tissue map from MRI. The μ-values of every tissue were estimated by inverting a linear relationship involving the partial path lengths and measured radioactivity intensity. Validation of the proposed method was performed by calculating a fixed- point data set based upon real a real transmission scan. The root-mean-square error between the μ-values derived from a conventional transmission scan and those obtained with our proposed method were 2.4±1.4%, 17.4±9.1% and 6.6±4.3% for brain, bone and soft tissue other than brain, respectively. Although the error estimates for bone and soft tissue are not insignificant, the method we propose is able to estimate the brain μ-value accurately and it is this factor that most strongly affects the quantitative value of PET images because of the large volumetric ratio of the brain. -- Highlights: • An MRI-derived µ-map for the attenuation correction of PET images is proposed. • Method relies on segmentation of MRI and a fixed-point source transmission scan. • Tissue segmentation reduces the number of unknown µ-values. • Method

Investigation of multilayered nanocomposites as low energy X-Rays attenuators

Energy Technology Data Exchange (ETDEWEB)

Silva, Liliane; Batista, Adriana S.M.; Nascimento, Jefferson P.; Furtado, Clascídia A.; Faria, Luiz O., E-mail: asfisica@gmail.com, E-mail: adriananuclear@yahoo.com.br, E-mail: farialo@cdtn.br, E-mail: nascimentopatricio@yahoo.com.br, E-mail: clas@cdtn.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-11-01

The development of radiation attenuating materials has application in radioprotection and conditioning of short-lived waste. Polymeric materials can serve as a matrix for the dispersion of nanomaterials with good attenuation features, resulting in lightweight, conformable, flexible and easy-to-process materials. Thus, some well-known shielding materials could be used in low proportion for the formation of new materials. On the other hand, nanostructured carbon materials, such as graphene oxide (GO) and carbon nanotubes (NTCs), have been reported recently to show enhanced attenuation properties. In this sense, polymeric matrixes provide the necessary flexibility for use in various applications that require molding. For the present work, poly(vinylidene fluoride) [PVDF] homopolymers and its fluorinated copolymers were filled with nanosized metallic and graphene oxides in order to produce nanocomposites with increased low energy X-ray attenuation efficiency. Film samples of PVDF/reduced Graphene Oxide [PVDF/rGO] and Poly(vinylidene fluoride – tryfluorethylene)/Barium Oxide [P(VDF-TrFE)/BaO] were synthesized. In a second step, the samples were then sandwiched between Kapton® layers and exposed to X-rays source (8.5 keV). The samples were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The attenuation coefficient was evaluated and compared with the attenuation of the individual constituents. It was observed an increase in the linear attenuation coefficient of the layered materials, justifying further investigation of these nanostructured composites as X-ray or gamma radiation attenuators. (author)

Investigation of multilayered nanocomposites as low energy X-Rays attenuators

International Nuclear Information System (INIS)

Silva, Liliane; Batista, Adriana S.M.; Nascimento, Jefferson P.; Furtado, Clascídia A.; Faria, Luiz O.

2017-01-01

The development of radiation attenuating materials has application in radioprotection and conditioning of short-lived waste. Polymeric materials can serve as a matrix for the dispersion of nanomaterials with good attenuation features, resulting in lightweight, conformable, flexible and easy-to-process materials. Thus, some well-known shielding materials could be used in low proportion for the formation of new materials. On the other hand, nanostructured carbon materials, such as graphene oxide (GO) and carbon nanotubes (NTCs), have been reported recently to show enhanced attenuation properties. In this sense, polymeric matrixes provide the necessary flexibility for use in various applications that require molding. For the present work, poly(vinylidene fluoride) [PVDF] homopolymers and its fluorinated copolymers were filled with nanosized metallic and graphene oxides in order to produce nanocomposites with increased low energy X-ray attenuation efficiency. Film samples of PVDF/reduced Graphene Oxide [PVDF/rGO] and Poly(vinylidene fluoride – tryfluorethylene)/Barium Oxide [P(VDF-TrFE)/BaO] were synthesized. In a second step, the samples were then sandwiched between Kapton® layers and exposed to X-rays source (8.5 keV). The samples were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The attenuation coefficient was evaluated and compared with the attenuation of the individual constituents. It was observed an increase in the linear attenuation coefficient of the layered materials, justifying further investigation of these nanostructured composites as X-ray or gamma radiation attenuators. (author)

Gamma-ray attenuation studies of PbO-BaO-B2O3 glass system

International Nuclear Information System (INIS)

Singh, Narveer; Singh, Kanwar Jit; Singh, Kulwant; Singh, Harvinder

2006-01-01

PbO-BaO-B 2 O 3 glass system has been investigated in terms of molar mass, mass attenuation coefficient and half value layer parameters by using gamma-ray at 511,662 and 1274keV photon energies. Gamma-ray attenuation coefficients of the prepared glass samples have been compared with tabulations based upon the results of XCOM. Good agreement has been observed between experimental and theoretical tabulations. Our results have uncertainty less than 3%. Radiation shielding properties of the glass system have been compared with some standard radiation shielding concretes

GPR measurements of attenuation in concrete

Science.gov (United States)

Eisenmann, David; Margetan, Frank J.; Pavel, Brittney

2015-03-01

Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups.

GPR measurements of attenuation in concrete

International Nuclear Information System (INIS)

Eisenmann, David; Margetan, Frank J.; Pavel, Brittney

2015-01-01

Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups

GPR measurements of attenuation in concrete

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, David, E-mail: djeisen@cnde.iastate.edu; Margetan, Frank J., E-mail: djeisen@cnde.iastate.edu; Pavel, Brittney, E-mail: djeisen@cnde.iastate.edu [Center for Nondestructive Evaluation, Iowa State University, 1915 Scholl Road, Ames, IA 50011-3042 (United States)

2015-03-31

Ground-penetrating radar (GPR) signals from concrete structures are affected by several phenomenon, including: (1) transmission and reflection coefficients at interfaces; (2) the radiation patterns of the antenna(s) being used; and (3) the material properties of concrete and any embedded objects. In this paper we investigate different schemes for determining the electromagnetic (EM) attenuation of concrete from measured signals obtained using commercially-available GPR equipment. We adapt procedures commonly used in ultrasonic inspections where one compares the relative strengths of two or more signals having different travel paths through the material of interest. After correcting for beam spread (i.e., diffraction), interface phenomena, and equipment amplification settings, any remaining signal differences are assumed to be due to attenuation thus allowing the attenuation coefficient (say, in dB of loss per inch of travel) to be estimated. We begin with a brief overview of our approach, and then discuss how diffraction corrections were determined for our two 1.6 GHz GPR antennas. We then present results of attenuation measurements for two types of concrete using both pulse/echo and pitch/catch measurement setups.

Iron influence in self-attenuation of gamma radiation in sand samples

Energy Technology Data Exchange (ETDEWEB)

Aquino, Reginaldo R.; Cavalcante, Fernanda; Pecequilo, Brigitte R.S, E-mail: raquino@ipen.br, E-mail: fcavalcante@ipen.br, E-mail: brigitte@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil)

2013-07-01

Self-attenuation of gamma rays are usually observed in sand samples, due to the presence of iron particles of natural or anthropogenic causes, which may lead to misleading activities concentrations results. As iron atoms are often present in sand samples, the self-attenuation contribution from this mineral requires special attention when assessing sand samples radioactivity. This contributions in verified in the in the present study, using several silica (sand-like) samples doped with different concentrations of iron. The samples were arranged with pure SiO{sub 4} (98,9%) mineral from the region of Setiba, (Espirito Santo state, Brazil) and Itabirito mineral, from Itabira (Minas Gerais state, Brazil), using standard 100 mL high density polyethylene (HDPE) flat-botton cylindrical flasks, each sealed using a 52.5 mm plan screw cap and bubble spigot. Three samples were arranged in different concentrations - Fe 25% and SiO{sub 4} 75%; Fe 50% and SiO{sub 4} 50%; Fe 75% and SiO{sub 4} 25% and two other samples were assembled in the same geometry, using 100% SiO{sub 4} and 100% Fe. These samples were exposed to a large spectrum of gamma radiation (121 keV to 1408 keV) emitted by sources of {sup 60}Co, {sup 137}Cs and {sup 152}Eu. These gamma radiations were collimated and directed over the doped samples in a high resolution gamma ray spectrometer, whose spectra were analyzed with the Winner Gamma software. The matrix effect intensity is inferred by the percentage differences observed in varying the iron concentration that proved to be more intense for lower energy radiation. (author)

The LCLS Gas Attenuator Revisited

International Nuclear Information System (INIS)

Ryutov, D

2005-01-01

In the report ''X-ray attenuation cell'' [1] a preliminary analysis of the gas attenuator for the Linac Coherent Light Source (LCLS) was presented. This analysis was carried out for extremely stringent set of specifications. In particular, a very large diameter for the unobstructed beam was set (1 cm) to accommodate the spontaneous radiation; the attenuator was supposed to cover the whole range of energies of the coherent radiation, from 800 eV to 8000 eV; the maximum attenuation was set at the level of 10 4 ; the use of solid attenuators was not allowed, as well as the use of rotating shutters. The need to reach a sufficient absorption at the high-energy end of the spectrum predetermined the choice of Xe as the working gas (in order to have a reasonable absorption at a not-too-high pressure). A sophisticated differential pumping system that included a Penning-type ion pump was suggested in order to minimize the gas leak into the undulator/accelerator part of the facility. A high cost of xenon meant also that an efficient (and expensive) gas-recovery system would have to be installed. The main parameter that determined the high cost and the complexity of the system was a large radius of the orifice. The present viewpoint allows for much smaller size of the orifice, r 0 = 1.5 mm. (1) The use of solid attenuators is also allowed (R.M. Bionta, private communication). It is, therefore, worthwhile to reconsider various parameters of the gas attenuator for these much less stringent conditions. This brief study should be considered as a physics input for the engineering design. As a working gas we consider now the argon, which, on the one hand, provides a reasonable absorption lengths and, on the other hand, is inexpensive enough to be exhausted into the atmosphere (no recovery). The absorption properties of argon are illustrated by Fig.1 where the attenuation factor A is shown for various beam energies, based on Ref. [2]. The other relevant parameters for argon are

Partial protection of baboons against Schistosoma mansoni using radiation-attenuated cryopreserved schistosomula

International Nuclear Information System (INIS)

James, E.R.; Dobinson, A.R.; Otieno, M.; Monorei, J.; Else, J.G.

1986-01-01

Three groups of five baboons were vaccinated in Kenya using three doses of 10,000 viable cryopreserved schistosomula attenuated with either 10, 20 or 60 krad 60 co-irradiation. The results from perfusion indicated reductions in worm burdens in the 10, 20 and 60 krad vaccinated groups of 18%, 23% and 20% respectively, none of which was statistically significant. No stunting of adult worms could be demonstrated in any of the groups. Mean tissue egg burdens were higher in all vaccinated groups and consequently egg production per worm pair was also higher than in the challenge controls. The logistics of preparing and delivering a cryopreserved radiation-attenuated vaccine were amply demonstrated; however, in this study the levels of protection achieved were not statistically significant; possible reasons for this are discussed. (author)

Accuracy and Radiation Dose of CT-Based Attenuation Correction for Small Animal PET: A Monte Carlo Simulation Study

International Nuclear Information System (INIS)

Yang, Ching-Ching; Chan, Kai-Chieh

2013-06-01

-Small animal PET allows qualitative assessment and quantitative measurement of biochemical processes in vivo, but the accuracy and reproducibility of imaging results can be affected by several parameters. The first aim of this study was to investigate the performance of different CT-based attenuation correction strategies and assess the resulting impact on PET images. The absorbed dose in different tissues caused by scanning procedures was also discussed to minimize biologic damage generated by radiation exposure due to PET/CT scanning. A small animal PET/CT system was modeled based on Monte Carlo simulation to generate imaging results and dose distribution. Three energy mapping methods, including the bilinear scaling method, the dual-energy method and the hybrid method which combines the kVp conversion and the dual-energy method, were investigated comparatively through assessing the accuracy of estimating linear attenuation coefficient at 511 keV and the bias introduced into PET quantification results due to CT-based attenuation correction. Our results showed that the hybrid method outperformed the bilinear scaling method, while the dual-energy method achieved the highest accuracy among the three energy mapping methods. Overall, the accuracy of PET quantification results have similar trend as that for the estimation of linear attenuation coefficients, whereas the differences between the three methods are more obvious in the estimation of linear attenuation coefficients than in the PET quantification results. With regards to radiation exposure from CT, the absorbed dose ranged between 7.29-45.58 mGy for 50-kVp scan and between 6.61-39.28 mGy for 80-kVp scan. For 18 F radioactivity concentration of 1.86x10 5 Bq/ml, the PET absorbed dose was around 24 cGy for tumor with a target-to-background ratio of 8. The radiation levels for CT scans are not lethal to the animal, but concurrent use of PET in longitudinal study can increase the risk of biological effects. The

Low skeletal muscle radiation attenuation and visceral adiposity are associated with overall survival and surgical site infections in patients with pancreatic cancer.

Science.gov (United States)

van Dijk, David P J; Bakens, Maikel J A M; Coolsen, Mariëlle M E; Rensen, Sander S; van Dam, Ronald M; Bours, Martijn J L; Weijenberg, Matty P; Dejong, Cornelis H C; Olde Damink, Steven W M

2017-04-01

Cancer cachexia and skeletal muscle wasting are related to poor survival. In this study, quantitative body composition measurements using computed tomography (CT) were investigated in relation to survival, post-operative complications, and surgical site infections in surgical patients with cancer of the head of the pancreas. A prospective cohort of 199 patients with cancer of the head of the pancreas was analysed by CT imaging at the L3 level to determine (i) muscle radiation attenuation (average Hounsfield units of total L3 skeletal muscle); (ii) visceral adipose tissue area; (iii) subcutaneous adipose tissue area; (iv) intermuscular adipose tissue area; and (v) skeletal muscle area. Sex-specific cut-offs were determined at the lower tertile for muscle radiation attenuation and skeletal muscle area and the higher tertile for adipose tissues. These variables of body composition were related to overall survival, severe post-operative complications (Dindo-Clavien ≥ 3), and surgical site infections (wounds inspected daily by an independent trial nurse) using Cox-regression analysis and multivariable logistic regression analysis, respectively. Low muscle radiation attenuation was associated with shorter survival in comparison with moderate and high muscle radiation attenuation [median survival 10.8 (95% CI: 8.8-12.8) vs. 17.4 (95% CI: 14.7-20.1), and 18.5 (95% CI: 9.2-27.8) months, respectively; P site infection rate, OR: 2.4 (95% CI: 1.1-5.3; P = 0.027). Low muscle radiation attenuation was associated with reduced survival, and high visceral adiposity was associated with an increase in surgical site infections. The strong correlation between muscle radiation attenuation and intermuscular adipose tissue suggests the presence of ectopic fat in muscle, warranting further investigation. CT image analysis could be implemented in pre-operative risk assessment to assist in treatment decision-making. © 2016 The Authors. Journal of Cachexia, Sarcopenia and Muscle

Evaluation of PVDF/MWCNT - ZRO{sub 2} nanocomposites for X-Rays attenuation

Energy Technology Data Exchange (ETDEWEB)

Pereira, Esther L.M.; Oliveira, Arno H., E-mail: esther_machado@outlook.com.br, E-mail: heeren@nuclear.ufmg.br [Universidade Federal de Minas Gerais (CCTN/UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Batista, Adriana S.M., E-mail: adriananuclear@yahoo.com.br [Departamento de Anatomia e Imagem (IMA), Belo Horizonte, MG (Brazil); Ribeiro, Fabíola A.S.; Santos, Adelina P.; Faria, Luiz O., E-mail: adelina@cdtn.br, E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

Recently, polymer-based nanocomposites filled with zirconium oxide (ZrO{sub 2}) nanoparticles have been suggested to be used in radiology procedures as X-rays attenuators. On the other hand, multi walled carbon nanotubes (MWCNT) has been reported to have enhanced X-rays attenuation features, when compared to other materials. In this work polymer-based nanocomposites made of a poly(vinylidene fluoride) [PVDF] homopolymer co-filled with MWCNT and zirconia (ZrO{sub 2}) were prepared, in order to investigate them for radiation shielding purposes. The PVDF matrix was added to 1.3% ZrO{sub 2} and the MWCNT in three different proportions: 0.33%, 0.66% and 1% of MWCNT.The arrangement between these materials causes new properties to be introduced to the constituents due to morphological modifications or electronic interactions between them, resulting in a nanocomposite of higher properties. The radiation shielding characterization was performed by using the X-ray beam of a XRD equipment. Photons with energies of 6.5 keV, 17.5 keV and 22.1 keV, corresponding to the anodes of cobalt, molybdenum and silver respectively, were used. The results are discussed in terms of the attenuation percentage of the nanocomposites produced in relation to the energy of the exposed radiation beam and varying the thickness of the samples. A comparison with cataloged aluminum data is also performed. (author)

Crystal glass used for X ray and gamma radiation shielding - Part two

International Nuclear Information System (INIS)

Antonio Filho, Joao

2007-01-01

Crystal glass has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass, in order to minimize exposure to individuals. However, properties of the radiation attenuation of crystal glass commercially available in Brazil, for the different types of energy are not known. For this reason, this work was carried out aiming to determine the radiation attenuation, transmission curves and Half Value Layer. In this work, ten plates of crystal glass, with dimensions of 20 cm x 20 cm and range of thicknesses from 0.5 to 2.0 cm, were used. The plates were X-ray irradiated with potential constants of 60, 80, 110, 150 kV and gamma radiation of 60 Co. Analysis in the properties of the 60 Co radiation attenuation of barite plaster and barite concrete commercially available in Brazil were also carried out. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/mA.min) at 1 meter as a function of thickness. The thickness equivalent of a half value layer and deci value layer of crystal glass for all types of radiation and energies studied was also determined. (author)

Inhomogeneity of neutron and gamma-ray attenuation in biological shields

Energy Technology Data Exchange (ETDEWEB)

El-bakkoush, F A; El-Ghobary, A M; Megahid, R M [Reactor and Neutron physics Department, Nuclear Research Center, A.E.A., Cairo (Egypt)

1997-12-31

Measurements have been carried-out to investigate the attenuation properties of some materials which are used as biological shields around nuclear radiation sources. Investigation was performed by measuring the transmitted fast neutron and gamma-spectra through cylindrical samples of magnetite- limonite, steel and cellulose shields. The neutron and gamma spectra were measured by a neutron-gamma spectrometer with stilbene scintillator. Discrimination between neutron and gamma pulses was achieved by a discrimination method. The obtained results are displayed in the form of neutron and gamma spectra and attenuation relations which are used to derive the total macroscopic cross-sections for neutrons and total linear attenuation coefficients for gamma-rays. The values of neutron and gamma relaxation lengths are also derived for the investigated materials. 10 figs., 1 tabs.

The properties of undulator radiation

International Nuclear Information System (INIS)

Howells, M.R.; Kincaid, B.M.

1993-09-01

A new generation of synchrotron radiation light sources covering the VUV, soft x-ray, and hard x-ray spectral regions is under construction in several countries. These sources are designed specifically to use periodic magnetic undulators and low-emittance electron or positron beams to produce high-brightness near-diffraction-limited synchrotron radiation beams. Some of the novel features of the new sources are discussed, along with the characteristics of the radiation produced, with emphasis on the Advanced Light Source, a third-generation 1.5 GeV storage ring optimized for undulator use. A review of the properties of undulator radiation is presented, followed by a discussion of some of the unique challenges being faced by the builders and users of the new undulator sources. These include difficult mechanical and magnetic tolerance limits, a complex interaction with the storage ring, high x-ray beam power, partial coherence, harmonics, optics contamination, and the unusual spectral and angular properties of undulator radiation

Attenuation of radiological consequences from CDA's by radiation. Progress report, October 1, 1976--September 31, 1977

International Nuclear Information System (INIS)

Chan, S.H.

1977-01-01

This technical progress report summarizes the research work accomplished during the first six months of the investigation on the significance of radiation heat transfer in attenuating the radiological consequences from LMFBR core disruptive accidents. Considerable progress has been made in modeling and computing the effects of radiative cooling on a rising HCDA bubble buoyant through a sodium pool. Our results reveal that most of the fuel vapor within the bubble can be effectively condensed out by radiating cooling. The finding has a profound implication as it could lead to a substantial reduction in subsequent aerosal releases

The importance of secondary radiation at radiation protection clothing; Die Bedeutung der Sekundaerstrahlung bei Strahlenschutzkleidung

Energy Technology Data Exchange (ETDEWEB)

Eder, Heinrich

2017-07-01

For a long time, the protective material lead was seen as ''gold standard'' for the shielding of photon radiation (X-ray and γ-rays). At long sight, however, lead should be eliminated from medical products. When irradiated, substitutes of lead can produce much more secondary radiation. Moreover, the radiobiological impact of the low energetic secondary radiation has to be rated higher than that of primary radiation. With the introduction of the new measuring standard IEC 6133-1 secondary radiation now is considered when evaluating attenuation properties of protective clothing.

Impact attenuation properties of jazz shoes alter lower limb joint stiffness during jump landings.

Science.gov (United States)

Fong Yan, Alycia; Smith, Richard M; Hiller, Claire E; Sinclair, Peter J

2017-05-01

To quantify the impact attenuation properties of the jazz shoes, and to investigate the in-vivo effect of four jazz shoe designs on lower limb joint stiffness during a dance-specific jump. Repeated measures. A custom-built mechanical shoe tester similar to that used by athletic shoe companies was used to vertically impact the forefoot and heel region of four different jazz shoe designs. Additionally, dancers performed eight sautés in second position in bare feet and the shoe conditions. Force platforms and 3D-motion capture were used to analyse the joint stiffness of the midfoot, ankle, knee and hip during the jump landings. Mechanical testing of the jazz shoes revealed significant differences in impact attenuation characteristics among each of the jazz shoe designs. Gross knee and midfoot joint stiffness were significantly affected by the jazz shoe designs in the dancers' jump landings. The tested jazz shoe designs altered the impact attenuating capacity of jump landing technique in dancers. The cushioned jazz shoes are recommended particularly for injured dancers to reduce impact on the lower limb. Jazz shoe design should consider the impact attenuation properties of the forefoot region, due to the toe-strike landing technique in dance movement. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Efficiency and attenuation correction factors determination in gamma spectrometric assay of bulk samples using self radiation

International Nuclear Information System (INIS)

Haddad, Kh.

2009-02-01

Gamma spectrometry forms the most important and capable tool for measuring radioactive materials. Determination of the efficiency and attenuation correction factors is the most tedious problem in the gamma spectrometric assay of bulk samples. A new experimental and easy method for these correction factors determination using self radiation was proposed in this work. An experimental study of the correlation between self attenuation correction factor and sample thickness and its practical application was also introduced. The work was performed on NORM and uranyl nitrate bulk sample. The results of proposed methods agreed with those of traditional ones.(author)

Analysis of biological samples by x-ray attenuation measurements

International Nuclear Information System (INIS)

Cesareo, R.

1988-01-01

Over the last few years there has been an increasing interest in X-ray attenuation measurements, mainly due to the enormous development of computer assisted tomography (CAT). With CAT, analytical information concerning the density and the mean atomic number distributions in a sample is deduced from a large number of attenuation measurements. Particular transmission methods developed, based on the differential attenuation method are discussed. The theoretical background for attenuation of radiation and for differential attenuation of radiation is given. Details about the generation of monoenergetic X-rays are discussed. Applications of attenuation measurements in the field of Medicine are presented

Some properties of Cerenkov radiation due to the finite thickness of the radiator

International Nuclear Information System (INIS)

Kobzev, A.P.; Frank, I.M.

1981-01-01

The properties of Cerenkov radiation are analyzed for a small radiator thickness. It is shown that the directionality of the radiation, its threshold properties, and also the dependence on the electron energy and radiator thickness differ substantially from the well known characteristics of Cerenkov radiation corresponding to the case of an unlimited particle trajectory in an extended medium. We have experimentally studied the directionality and energy characteristics of radiation excited by electrons in a mica target of thickness 12 400 A at wavelength 4000 A. The experimental results are in good agreement with the calculations

Radiation-resistant composite for biological shield of personnel

Science.gov (United States)

Barabash, D. E.; Barabash, A. D.; Potapov, Yu B.; Panfilov, D. V.; Perekalskiy, O. E.

2017-10-01

This article presents the results of theoretical and practical justification for the use of polymer concrete based on nonisocyanate polyurethanes in biological shield structures. We have identified the impact of ratio: polymer - radiation-resistant filling compound on the durability and protection properties of polymer concrete. The article expounds regression dependence of the change of basic properties of the aforementioned polymer concrete on the absorbed radiation dose rate. Synergy effect in attenuation of radioactivity release in case of conjoint use of hydrogenous polymer base and radiation-resistant powder is also addressed herein.

Protective properties of radiation-modified polyethylene

Energy Technology Data Exchange (ETDEWEB)

Surnina, N.N.; Saltykova, L.A.; Strochkova, E.M.; Tatarenko, O.F.

1986-09-01

A study was made of the mass transfer of corrosive liquids and gases through polyethylene films modified by radiation surface grafting. Studies were performed on an unstabilized type A film with graft adhesion-active layer based on polymethacrylic acid. The protective properties of the polymer coating in corrosive fluids with low vapor tension were estimated by impedance measurements. Steel specimens with a protective coating of radiation-modified polyethylene film were exposed to 10% sulfuric acid at room temperature. The results indicated that the acid did not penetrate through to the metal surface. The films retain their protective properties and protect the metal from the acid. Radiation modification significantly improves the adhesion of polyethylene to metals without reducing physical and mechanical properties of the polymers. 50 references, 1 figure.

Property of the diamond radiation detector

International Nuclear Information System (INIS)

Sochor, V.; Cechak, T.; Sopko, B.

2008-01-01

The outstanding properties of diamond, such as radiation hardness, high carrier mobility, high band gap and breakdown field, distinguish it as a good candidate for radiation detectors. In the dosimetry for radiotherapy is permanently searched the detector with high sensitivity, high stability, linear dependence of the response, small size, tissue equivalent material and fast response, for the measuring of the temporal and space variations of the dose. The diamond detector properties as high sensitivity, good spatial and temporal resolution, low Leakage currents, low capacitance, possibility to fabricate robust and compact device and high temperature operation make it possible to use these detectors in many fields from high energy physics till radiation monitoring, from Medical therapy dosimetry till synchrotron radiation measurement. (authors)

Spectral radiative property control method based on filling solution

International Nuclear Information System (INIS)

Jiao, Y.; Liu, L.H.; Hsu, P.-F.

2014-01-01

Controlling thermal radiation by tailoring spectral properties of microstructure is a promising method, can be applied in many industrial systems and have been widely researched recently. Among various property tailoring schemes, geometry design of microstructures is a commonly used method. However, the existing radiation property tailoring is limited by adjustability of processed microstructures. In other words, the spectral radiative properties of microscale structures are not possible to change after the gratings are fabricated. In this paper, we propose a method that adjusts the grating spectral properties by means of injecting filling solution, which could modify the thermal radiation in a fabricated microstructure. Therefore, this method overcomes the limitation mentioned above. Both mercury and water are adopted as the filling solution in this study. Aluminum and silver are selected as the grating materials to investigate the generality and limitation of this control method. The rigorous coupled-wave analysis is used to investigate the spectral radiative properties of these filling solution grating structures. A magnetic polaritons mechanism identification method is proposed based on LC circuit model principle. It is found that this control method could be used by different grating materials. Different filling solutions would enable the high absorption peak to move to longer or shorter wavelength band. The results show that the filling solution grating structures are promising for active control of spectral radiative properties. -- Highlights: • A filling solution grating structure is designed to adjust spectral radiative properties. • The mechanism of radiative property control is studied for engineering utilization. • Different grating materials are studied to find multi-functions for grating

Gamma radiation effects on polydimethylsiloxane rubber foams under different radiation conditions

Science.gov (United States)

Sui, H. L.; Liu, X. Y.; Zhong, F. C.; Li, X. Y.; Wang, L.; Ju, X.

2013-07-01

Polydimethylsiloxane rubber foams were irradiated by gamma ray under different radiation conditions designed by orthogonal design method. Compression set measurement, infrared attenuated total reflectance spectroscopy (ATR) and X-ray induced photoelectron spectroscopy (XPS) were used. Three aging factors' influence effects on the mechanical property and chemical structure were studied. It was found that among the three factors and the chosen levels, both properties were affected most by radiation dose, while radiation dose rate had no obvious influence on both properties. The stiffening of the rubber foams was caused by cross-linking reactions in the Si-CH3. At the same radiation dose, the rigidity of the foams irradiated in air was lower than that in nitrogen. When polydimethylsiloxane was irradiated at a high dose in sealed nitrogen atmosphere, carbon element distribution would be changed. Hydrocarbons produced by gamma ray in the sealed tube would make the carbon content in the skin-deep higher than that in the middle, which indicated that polydimethylsiloxane rubber foams storing in a sealed atmosphere filled with enough hydrocarbons should be helpful to extend the service life.

Gamma radiation effects on polydimethylsiloxane rubber foams under different radiation conditions

Energy Technology Data Exchange (ETDEWEB)

Sui, H.L. [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China); Institute of Chemical Materials, CAEP, Mianyang 621900 (China); Liu, X.Y.; Zhong, F.C. [Institute of Chemical Materials, CAEP, Mianyang 621900 (China); Li, X.Y. [Institute of Nuclear Physics and Chemistry, CAEP, Mianyang 621900 (China); Wang, L. [Institute of Chemical Materials, CAEP, Mianyang 621900 (China); Ju, X., E-mail: jux@ustb.edu.cn [Department of Physics, University of Science and Technology Beijing, Beijing 100083 (China)

2013-07-15

Polydimethylsiloxane rubber foams were irradiated by gamma ray under different radiation conditions designed by orthogonal design method. Compression set measurement, infrared attenuated total reflectance spectroscopy (ATR) and X-ray induced photoelectron spectroscopy (XPS) were used. Three aging factors’ influence effects on the mechanical property and chemical structure were studied. It was found that among the three factors and the chosen levels, both properties were affected most by radiation dose, while radiation dose rate had no obvious influence on both properties. The stiffening of the rubber foams was caused by cross-linking reactions in the Si–CH{sub 3}. At the same radiation dose, the rigidity of the foams irradiated in air was lower than that in nitrogen. When polydimethylsiloxane was irradiated at a high dose in sealed nitrogen atmosphere, carbon element distribution would be changed. Hydrocarbons produced by gamma ray in the sealed tube would make the carbon content in the skin-deep higher than that in the middle, which indicated that polydimethylsiloxane rubber foams storing in a sealed atmosphere filled with enough hydrocarbons should be helpful to extend the service life.

Electromagnetic radiation properties of foods and agricultural products

International Nuclear Information System (INIS)

Mohsenin, N.N.

1984-01-01

In this book, the author examines the effects of the various regions of the electromagnetic radiation spectrum on foods and agricultural products. Among the regions of the electromagnetic radiation spectrum covered are high-energy beta and neutron particles, gamma-rays and X-rays, to lower-energy visible, near infrared, infrared, microwave and low-energy radiowaves and electric currents. Dr. Mohsenin applies these electromagnetic phenomena to food products such as fruits, vegetables, seeds, dairy products, meat and processed foods. Contents: Some Basic Concepts of Electromagnetic Radiation. Basic Instruments for Measurement of Optical Properties. Applications of Radiation in the Visible Spectrum. Color and its Measurement. Sorting for Color and Appearance. Near-Infrared and Infrared Radiation Applications. Applications of High-Energy Radiation. Related Concepts of Microwaves, Radiowaves, and Electric Currents. Measurement of Electrical Properties of Foods and Agricultural Products. Applications of Electrical Properties. Appendix, Cited References. Subject Index

Effect of Steel Fiber Addition on Mechanical Properties and gamma-Ray Attenuation for Ordinary Concrete Used in El-Gabal El-Akhdar Area in Libya for Radiation Shielding Purposes

International Nuclear Information System (INIS)

Ikraiam, F.A.; Ali, J.M.; Abd El-Latif, A.; Abd ELazziz, A.

2009-01-01

This work deals with the study of ordinary concrete reinforced with steel fibers where the concrete was prepared from limestone ores as coarse aggregate, and sand as fine aggregate, in El-Gabal El-Akhdar in Libya in order to study some mechanical properties and gamma ray attenuation. For mechanical properties, compressive and tensile strengths have been studied, where tensile strength improved by a factor 1.189 at 3% steel fiber content in comparison with reference sample (0%), whereas the compressive strength improved by a factor of 1.012 at 1% steel fiber content. In relation to the concrete density, it is found that the optimum density was 2.217g/cm3 at 3% where the factor of improvement was 1.1. For gamma ray attenuation, the measurements have been obtained by a collimated beam of gamma ray from sources 60 Co, 22 Na and 137 Cs using a gamma ray spectrometer MCA cassy with inorganic scintillator Na(Tl). The total linear attenuation coefficient (μ cm - 1), mean free path length (λ), HVT (τ1/2) and TVT (τ1/10) are all evaluated in this study. The study reveals that concrete sample with 3% steel fiber content has the optimum values of all these nuclear parameters

Investigation of Radiation Protection Methodologies for Radiation Therapy Shielding Using Monte Carlo Simulation and Measurement

Science.gov (United States)

Tanny, Sean

The advent of high-energy linear accelerators for dedicated medical use in the 1950's by Henry Kaplan and the Stanford University physics department began a revolution in radiation oncology. Today, linear accelerators are the standard of care for modern radiation therapy and can generate high-energy beams that can produce tens of Gy per minute at isocenter. This creates a need for a large amount of shielding material to properly protect members of the public and hospital staff. Standardized vault designs and guidance on shielding properties of various materials are provided by the National Council on Radiation Protection (NCRP) Report 151. However, physicists are seeking ways to minimize the footprint and volume of shielding material needed which leads to the use of non-standard vault configurations and less-studied materials, such as high-density concrete. The University of Toledo Dana Cancer Center has utilized both of these methods to minimize the cost and spatial footprint of the requisite radiation shielding. To ensure a safe work environment, computer simulations were performed to verify the attenuation properties and shielding workloads produced by a variety of situations where standard recommendations and guidance documents were insufficient. This project studies two areas of concern that are not addressed by NCRP 151, the radiation shielding workload for the vault door with a non-standard design, and the attenuation properties of high-density concrete for both photon and neutron radiation. Simulations have been performed using a Monte-Carlo code produced by the Los Alamos National Lab (LANL), Monte Carlo Neutrons, Photons 5 (MCNP5). Measurements have been performed using a shielding test port designed into the maze of the Varian Edge treatment vault.

k-space sampling optimization for ultrashort TE imaging of cortical bone: Applications in radiation therapy planning and MR-based PET attenuation correction

International Nuclear Information System (INIS)

Hu, Lingzhi; Traughber, Melanie; Su, Kuan-Hao; Pereira, Gisele C.; Grover, Anu; Traughber, Bryan; Muzic, Raymond F. Jr.

2014-01-01

Purpose: The ultrashort echo-time (UTE) sequence is a promising MR pulse sequence for imaging cortical bone which is otherwise difficult to image using conventional MR sequences and also poses strong attenuation for photons in radiation therapy and PET imaging. The authors report here a systematic characterization of cortical bone signal decay and a scanning time optimization strategy for the UTE sequence through k-space undersampling, which can result in up to a 75% reduction in acquisition time. Using the undersampled UTE imaging sequence, the authors also attempted to quantitatively investigate the MR properties of cortical bone in healthy volunteers, thus demonstrating the feasibility of using such a technique for generating bone-enhanced images which can be used for radiation therapy planning and attenuation correction with PET/MR. Methods: An angularly undersampled, radially encoded UTE sequence was used for scanning the brains of healthy volunteers. Quantitative MR characterization of tissue properties, including water fraction and R2 ∗ = 1/T2 ∗ , was performed by analyzing the UTE images acquired at multiple echo times. The impact of different sampling rates was evaluated through systematic comparison of the MR image quality, bone-enhanced image quality, image noise, water fraction, and R2 ∗ of cortical bone. Results: A reduced angular sampling rate of the UTE trajectory achieves acquisition durations in proportion to the sampling rate and in as short as 25% of the time required for full sampling using a standard Cartesian acquisition, while preserving unique MR contrast within the skull at the cost of a minimal increase in noise level. The R2 ∗ of human skull was measured as 0.2–0.3 ms −1 depending on the specific region, which is more than ten times greater than the R2 ∗ of soft tissue. The water fraction in human skull was measured to be 60%–80%, which is significantly less than the >90% water fraction in brain. High-quality, bone

Coniferyl aldehyde attenuates radiation enteropathy by inhibiting cell death and promoting endothelial cell function.

Science.gov (United States)

Jeong, Ye-Ji; Jung, Myung Gu; Son, Yeonghoon; Jang, Jun-Ho; Lee, Yoon-Jin; Kim, Sung-Ho; Ko, Young-Gyo; Lee, Yun-Sil; Lee, Hae-June

2015-01-01

Radiation enteropathy is a common complication in cancer patients. The aim of this study was to investigate whether radiation-induced intestinal injury could be alleviated by coniferyl aldehyde (CA), an HSF1-inducing agent that increases cellular HSP70 expression. We systemically administered CA to mice with radiation enteropathy following abdominal irradiation (IR) to demonstrate the protective effects of CA against radiation-induced gastrointestinal injury. CA clearly alleviated acute radiation-induced intestinal damage, as reflected by the histopathological data and it also attenuated sub-acute enteritis. CA prevented intestinal crypt cell death and protected the microvasculature in the lamina propria during the acute and sub-acute phases of damage. CA induced HSF1 and HSP70 expression in both intestinal epithelial cells and endothelial cells in vitro. Additionally, CA protected against not only the apoptotic cell death of both endothelial and epithelial cells but also the loss of endothelial cell function following IR, indicating that CA has beneficial effects on the intestine. Our results provide novel insight into the effects of CA and suggest its role as a therapeutic candidate for radiation-induced enteropathy due to its ability to promote rapid re-proliferation of the intestinal epithelium by the synergic effects of the inhibition of cell death and the promotion of endothelial cell function.

Crystal glass and barite used for x ray and gamma radiation shielding

International Nuclear Information System (INIS)

Antonio Filho, Joao

2008-01-01

Full text: Crystal glass, barite plaster and barite concrete has been widely used as shielding material in gamma radiation sources as well as x-ray generating equipment to replace the plumbiferous glass and in the wall covering, in order to minimize exposure to individuals. However, properties of the radiation attenuation of crystal glass commercially available in Brazil, for the different types of energy are not known. For this reason, this work was carried out aiming to determine the radiation attenuation, transmission curves and Half Value Layer. In this work, ten plates of crystal glass, with dimensions of 20 cm x 20 cm and range of thicknesses from 0.5 to 2.0 cm, and ten plates of barite plaster and five plates of barite concrete, with dimensions of 20 x 20 cm 2 and range of thicknesses from 1,0 to 5,0 cm, were used. The plates were X-ray irradiated with potential constants of 60, 80, 110, 150 kV and gamma radiation of 60 Co. Analysis in the properties of the 60 Co radiation attenuation of barite plaster and barite concrete commercially available in Brazil were also carried out. The curves of attenuation and of transmission were obtained for crystal glass, barite plaster and barite concrete (mGy/m A.min) at 1 meter as a function of thickness. The thickness equivalent of a half value layer and deci value layer of crystal glass for all types of radiation and energies studied was also determined. Although their use permits the dimensioning of the armor covering for external x-radiation whit precision and safety without elevating the cost of protection. (author)

Radiation shielding properties of high performance concrete reinforced with basalt fibers infused with natural and enriched boron

Energy Technology Data Exchange (ETDEWEB)

Zorla, Eyüp; Ipbüker, Cagatay [University of Tartu, Institute of Physics (Estonia); Biland, Alex [US Basalt Corp., Houston (United States); Kiisk, Madis [University of Tartu, Institute of Physics (Estonia); Kovaljov, Sergei [OÜ Basaltest, Tartu (Estonia); Tkaczyk, Alan H. [University of Tartu, Institute of Physics (Estonia); Gulik, Volodymyr, E-mail: volodymyr.gulik@gmail.com [Institute for Safety Problems of Nuclear Power Plants, Lysogirska 12, of. 201, 03028 Kyiv (Ukraine)

2017-03-15

Highlights: • Basalt fiber infused with natural and enriched boron in varying proportions. • Gamma-ray attenuation remains stable with addition of basalt-boron fiber. • Improvement in neutron shielding for nuclear facilities producing fast fission spectrum. • Basalt-boron fiber could decrease the shielding thickness in thermal spectrum reactors. - Abstract: The importance of radiation shielding is increasing in parallel with the expansion of the application areas of nuclear technologies. This study investigates the radiation shielding properties of two types of high strength concrete reinforced with basalt fibers infused with 12–20% boron oxide, containing varying fractions of natural and enriched boron. The gamma-ray shielding characteristics are analyzed with the help of the WinXCom, whereas the neutron shielding characteristics are modeled and computed by Monte Carlo Serpent code. For gamma-ray shielding, the attenuation coefficients of the studied samples do not display any significant variation due to the addition of basalt-boron fibers at any mixing proportion. For neutron shielding, the addition of basalt-boron fiber has negligible effects in the case of very fast neutrons (14 MeV), but it could considerably improve the neutron shielding of concrete for nuclear facilities producing a fast fission spectrum (e.g. with reactors as BN-800, FBTR) and thermal neutron spectrum (Light Water Reactors (LWR)). It was also found that basalt-boron fiber could decrease the thickness of radiation shielding material in thermal spectrum reactors.

Radiation shielding properties of high performance concrete reinforced with basalt fibers infused with natural and enriched boron

International Nuclear Information System (INIS)

Zorla, Eyüp; Ipbüker, Cagatay; Biland, Alex; Kiisk, Madis; Kovaljov, Sergei; Tkaczyk, Alan H.; Gulik, Volodymyr

2017-01-01

Highlights: • Basalt fiber infused with natural and enriched boron in varying proportions. • Gamma-ray attenuation remains stable with addition of basalt-boron fiber. • Improvement in neutron shielding for nuclear facilities producing fast fission spectrum. • Basalt-boron fiber could decrease the shielding thickness in thermal spectrum reactors. - Abstract: The importance of radiation shielding is increasing in parallel with the expansion of the application areas of nuclear technologies. This study investigates the radiation shielding properties of two types of high strength concrete reinforced with basalt fibers infused with 12–20% boron oxide, containing varying fractions of natural and enriched boron. The gamma-ray shielding characteristics are analyzed with the help of the WinXCom, whereas the neutron shielding characteristics are modeled and computed by Monte Carlo Serpent code. For gamma-ray shielding, the attenuation coefficients of the studied samples do not display any significant variation due to the addition of basalt-boron fibers at any mixing proportion. For neutron shielding, the addition of basalt-boron fiber has negligible effects in the case of very fast neutrons (14 MeV), but it could considerably improve the neutron shielding of concrete for nuclear facilities producing a fast fission spectrum (e.g. with reactors as BN-800, FBTR) and thermal neutron spectrum (Light Water Reactors (LWR)). It was also found that basalt-boron fiber could decrease the thickness of radiation shielding material in thermal spectrum reactors.

Thermophysical properties of polyethylene modified under γ radiation

International Nuclear Information System (INIS)

Shut, N.I.; Musaelyan, I.N.; Besklubenko, Yu.D.; Karpovich, N.B.; Kasperskij, A.V.

1986-01-01

Thermophysical properties (thermal conductivity, specific heat) of polyethylene (PE) modified under gamma radiation were studied. Thermophysical parameter dependences on the temperature (-100-+100 deg C) and an absorbed radiation dose are given. Degree of polymere crystallinity using a structural method for determination of the crystallinity degree by density was ascertained. It is shown that the PE thermophysical characteristics correlate to a value of absorbed gamma radiation dose, therefore gamma radiation can be recommended as a modifying factor for the production of polymer materials with the given properties

Assessment of dynamic material properties of intact rocks using seismic wave attenuation: an experimental study.

Science.gov (United States)

Wanniarachchi, W A M; Ranjith, P G; Perera, M S A; Rathnaweera, T D; Lyu, Q; Mahanta, B

2017-10-01

The mechanical properties of any substance are essential facts to understand its behaviour and make the maximum use of the particular substance. Rocks are indeed an important substance, as they are of significant use in the energy industry, specifically for fossil fuels and geothermal energy. Attenuation of seismic waves is a non-destructive technique to investigate mechanical properties of reservoir rocks under different conditions. The attenuation characteristics of five different rock types, siltstone, shale, Australian sandstone, Indian sandstone and granite, were investigated in the laboratory using ultrasonic and acoustic emission instruments in a frequency range of 0.1-1 MHz. The pulse transmission technique and spectral ratios were used to calculate the attenuation coefficient ( α ) and quality factor ( Q ) values for the five selected rock types for both primary ( P ) and secondary ( S ) waves, relative to the reference steel sample. For all the rock types, the attenuation coefficient was linearly proportional to the frequency of both the P and S waves. Interestingly, the attenuation coefficient of granite is more than 22% higher than that of siltstone, sandstone and shale for both P and S waves. The P and S wave velocities were calculated based on their recorded travel time, and these velocities were then used to calculate the dynamic mechanical properties including elastic modulus ( E ), bulk modulus ( K ), shear modulus ( µ ) and Poisson's ratio ( ν ). The P and S wave velocities for the selected rock types varied in the ranges of 2.43-4.61 km s -1 and 1.43-2.41 km h -1 , respectively. Furthermore, it was observed that the P wave velocity was always greater than the S wave velocity, and this confirmed the first arrival of P waves to the sensor. According to the experimental results, the dynamic E value is generally higher than the static E value obtained by unconfined compressive strength tests.

Ambient ultraviolet radiation induces protective responses in soybean but does not attenuate indirect defense

International Nuclear Information System (INIS)

Winter, Thorsten R.; Rostas, Michael

2008-01-01

We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels. - Ambient ultraviolet radiation does not alter induced VOC emission in soybean and thus host location of the parasitoid Cotesia marginiventris remains effective

Apparatus for minimizing radiation exposure and improving resolution in radiation imaging devices

International Nuclear Information System (INIS)

Ashe, J.B.; Williams, G.H.; Sypal, K.L.

1978-01-01

A collimator is disclosed for minimizing radiation exposure and improving resolution in radiation imaging devices. The collimator provides a penetrating beam of radiation from a source thereof, which beam is substantially non-diverging in at least one direction. In the preferred embodiment, the collimator comprises an elongated sandwich assembly of a plurality of layers of material exhibiting relatively high radiation attenuation characteristics, which attenuating layers are spaced apart and separated from one another by interleaved layers of material exhibiting relatively low radiation attenuation characteristics. The sandwich assembly is adapted for lengthwise disposition and orientation between a radiation source and a target or receiver such that the attenuating layers are parallel to the desired direction of the beam with the interleaved spacing layers providing direct paths for the radiation

Radiation shielding properties of barite coated fabric by computer programme

Energy Technology Data Exchange (ETDEWEB)

Akarslan, F.; Molla, T. [Suleyman Demirel University, Engineering Fac. Textile Dep., Isparta (Turkey); Üncü, I. S. [Suleyman Demirel University, Technological Fac. Electrical-Electronic Eng. Dep., Isparta (Turkey); Kılıncarslan, S., E-mail: seref@tef.sdu.edu.tr [Suleyman Demirel University, Engineering Fac. Civil Eng. Dep., Isparta (Turkey); Akkurt, I. [Suleyman Demirel University, Art and Science Fac., Physics Dep., Isparta (Turkey)

2015-03-30

With the development of technology radiation started to be used in variety of different fields. As the radiation is hazardous for human health, it is important to keep radiation dose as low as possible. This is done mainly using shielding materials. Barite is one of the important materials in this purpose. As the barite is not used directly it can be used in some other materials such as fabric. For this purposes barite has been coated on fabric in order to improve radiation shielding properties of fabric. Determination of radiation shielding properties of coated fabric has been done by using computer program written C# language. With this program the images obtained from digital Rontgen films is used to determine radiation shielding properties in terms of image processing numerical values. Those values define radiation shielding and in this way the coated barite effect on radiation shielding properties of fabric has been obtained.

Analysis of the variation of the attenuation curve in function of the radiation field size for k Vp X-ray beams using the MCNP-5C code

Energy Technology Data Exchange (ETDEWEB)

Fernandes, Marco A.R., E-mail: marco@cetea.com.b, E-mail: marfernandes@fmb.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina; Ribeiro, Victor A.B. [Universidade Estadual Paulista Julio de Mesquita Filho (IBB/UNESP), Botucatu, SP (Brazil). Inst. de Biociencias; Viana, Rodrigo S.S.; Coelho, Talita S. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The paper illustrates the use of the Monte Carlo method, MCNP-5C code, to analyze the attenuation curve behavior of the 50 kVp radiation beam from superficial radiotherapy equipment as Dermopan2 model. The simulations seek to verify the MCNP-5C code performance to study the variation of the attenuation curve - percentage depth dose (PDD) curve - in function of the radiation field dimension used at radiotherapy of skin tumors with 50 kVp X-ray beams. The PDD curve was calculated for six different radiation field sizes with circular geometry of 1.0, 2.0, 3.0, 4.0, 5.0 and 6.0 cm in diameter. The radiation source was modeled considering a tungsten target with inclination 30 deg, focal point of 6.5 mm in diameter and energy beam of 50 kVp; the X-ray spectrum was calculated with the MCNP-5C code adopting total filtration (beryllium window of 1 mm and aluminum additional filter of 1 mm). The PDD showed decreasing behavior with the attenuation depth similar what is presented on the literature. There was not significant variation at the PDD values for the radiation field between 1.0 and 4.0 cm in diameter. The differences increased for fields of 5.0 and 6.0 cm and at attenuation depth higher than 1.0 cm. When it is compared the PDD values for fields of 3.0 and 6.0 cm in diameter, it verifies the greater difference (12.6 %) at depth of 5.7 cm, proving the scattered radiation effect. The MCNP-5C code showed as an appropriate procedure to analyze the attenuation curves of the superficial radiotherapy beams. (author)

Antioxidants attenuate atherosclerotic plaque development in a balloon-denuded and -radiated hypercholesterolemic rabbit

International Nuclear Information System (INIS)

Leborgne, Laurent; Fournadjiev, Jana; Pakala, Rajbabu; Dilcher, Christian; Cheneau, Edouard; Wolfram, Roswitha; Hellinga, David; Seaborn, Rufus; O'Tio, Fermin; Waksman, Ron

2003-01-01

Background: Oxidation of lipoproteins is considered to be a key contributor to atherogenesis. Antioxidants are potential antiatherogenic agents because they can inhibit lipoprotein oxidation. Radiation has been shown to increase oxidative stress leading to increased atherogenesis. This study is designed to test the potential of antioxidants to inhibit atherosclerotic plaque progression in balloon-denuded and -radiated rabbits. Methods and Results: Two groups of New Zealand white rabbits (n=36) were fed with 1% cholesterol diet (control diet) or with 1% cholesterol diet containing a mixture of various antioxidants for 1 week. Iliac arteries in all the animals were balloon denuded and continued to fed with 0.15% cholesterol diet or 0.15% cholesterol diet containing antioxidants (antioxidant diet). Four weeks after balloon denudation one iliac artery in 12 animals from each group was radiated and all the animals were continued to be fed with the same diet. Four weeks after radiation animals were sacrificed and morphometric analysis of iliac arteries (n=12) in nonradiated and radiated animals were performed. Plaque area (PA) in the rabbits that were fed with cholesterol diet is 0.2±0.12 mm 2 , and it is increased by 2.75-fold (P<.05) in the radiated arteries of animals fed with cholesterol diet. Plaque area in the animals fed with antioxidant diet is 50% less then the one in the animals fed with cholesterol diet. Similarly, plaque area in radiated arteries of the animals fed with antioxidant diet is 50% less then the animals fed with cholesterol diet. Conclusion: Antioxidants significantly attenuate atherosclerotic plaque progression in balloon-injured and -radiated hypercholesterolemic rabbits

Application of conditional simulation of heterogeneous rock properties to seismic scattering and attenuation analysis in gas hydrate reservoirs

Science.gov (United States)

Huang, Jun-Wei; Bellefleur, Gilles; Milkereit, Bernd

2012-02-01

We present a conditional simulation algorithm to parameterize three-dimensional heterogeneities and construct heterogeneous petrophysical reservoir models. The models match the data at borehole locations, simulate heterogeneities at the same resolution as borehole logging data elsewhere in the model space, and simultaneously honor the correlations among multiple rock properties. The model provides a heterogeneous environment in which a variety of geophysical experiments can be simulated. This includes the estimation of petrophysical properties and the study of geophysical response to the heterogeneities. As an example, we model the elastic properties of a gas hydrate accumulation located at Mallik, Northwest Territories, Canada. The modeled properties include compressional and shear-wave velocities that primarily depend on the saturation of hydrate in the pore space of the subsurface lithologies. We introduce the conditional heterogeneous petrophysical models into a finite difference modeling program to study seismic scattering and attenuation due to multi-scale heterogeneity. Similarities between resonance scattering analysis of synthetic and field Vertical Seismic Profile data reveal heterogeneity with a horizontal-scale of approximately 50 m in the shallow part of the gas hydrate interval. A cross-borehole numerical experiment demonstrates that apparent seismic energy loss can occur in a pure elastic medium without any intrinsic attenuation of hydrate-bearing sediments. This apparent attenuation is largely attributed to attenuative leaky mode propagation of seismic waves through large-scale gas hydrate occurrence as well as scattering from patchy distribution of gas hydrate.

Gamma-ray attenuation coefficients in some heavy metal oxide borate glasses at 662 keV

International Nuclear Information System (INIS)

Khanna, A.; Bhatti, S.S.; Singh, K.J.; Thind, K.S.

1996-01-01

The linear attenuation coefficient (μ) and mass attenuation coefficients (μ/ρ) of glasses in three systems: xPbO(1-x)B 2 O 3 , 0.25PbO.xCdO(0.75-x)B 2 O 3 and xBi 2 O 3 (1-x)B 2 O 3 were measured at 662 keV. Appreciable variations were noted in the attenuation coefficients due to changes in the chemical composition of glasses. In addition to this, absorption cross-sections per atom were also calculated. A comparison of shielding properties of these glasses with standar d shielding materials like lead, lead glass and concrete has proven that these glasses have a potential application as transparent radiation shielding. (orig.)

PET attenuation correction for rigid MR Tx/Rx coils from 176Lu background activity

Science.gov (United States)

Lerche, Christoph W.; Kaltsas, Theodoris; Caldeira, Liliana; Scheins, Jürgen; Rota Kops, Elena; Tellmann, Lutz; Pietrzyk, Uwe; Herzog, Hans; Shah, N. Jon

2018-02-01

One challenge for PET-MR hybrid imaging is the correction for attenuation of the 511 keV annihilation radiation by the required RF transmit and/or RF receive coils. Although there are strategies for building PET transparent Tx/Rx coils, such optimised coils still cause significant attenuation of the annihilation radiation leading to artefacts and biases in the reconstructed activity concentrations. We present a straightforward method to measure the attenuation of Tx/Rx coils in simultaneous MR-PET imaging based on the natural 176Lu background contained in the scintillator of the PET detector without the requirement of an external CT scanner or PET scanner with transmission source. The method was evaluated on a prototype 3T MR-BrainPET produced by Siemens Healthcare GmbH, both with phantom studies and with true emission images from patient/volunteer examinations. Furthermore, the count rate stability of the PET scanner and the x-ray properties of the Tx/Rx head coil were investigated. Even without energy extrapolation from the two dominant γ energies of 176Lu to 511 keV, the presented method for attenuation correction, based on the measurement of 176Lu background attenuation, shows slightly better performance than the coil attenuation correction currently used. The coil attenuation correction currently used is based on an external transmission scan with rotating 68Ge sources acquired on a Siemens ECAT HR  +  PET scanner. However, the main advantage of the presented approach is its straightforwardness and ready availability without the need for additional accessories.

Cytokine production in BALB/c mice immunized with radiation attenuated third stage larvae of the filarial nematode, Brugia pahangi

International Nuclear Information System (INIS)

Bancroft, A.J.; Devaney, E.; Grencis, R.K.; Else, K.J.

1993-01-01

BALB/c mice immunized with radiation-attenuated third stage larvae of the filarial nematode Brugia pahangi are strongly immune to challenge infection. Investigation of the profile of cytokines secreted by spleen cells from immune mice stimulated in vitro with either parasite Ag or with Con A revealed high levels of IL-5 and IL-9 and moderate levels of IL-4. In contrast, secretion of IFN-γ by spleen cells from immune animals was negligible. Spleen cells from control mice secreted low levels of all cytokines assayed. Levels of parasite-specific IgE were significantly elevated in immune animals and a peripheral blood eosinophilia was observed, which exhibited a biphasic distribution. Our results are consistent with the preferential expansion of Th2 cells in immune animals and provide the basis for dissecting the means by which radiation-attenuated larvae of filarial nematodes stimulate immunity. 5l refs., 3 figs., 3 tabs

Thermal radiation properties of PTFE plasma

Science.gov (United States)

Liu, Xiangyang; Wang, Siyu; Zhou, Yang; Wu, Zhiwen; Xie, Kan; Wang, Ningfei

2017-06-01

To illuminate the thermal transfer mechanism of devices adopting polytetrafluoroethylene (PTFE) as ablation materials, the thermal radiation properties of PTFE plasma are calculated and discussed based on local thermodynamic equilibrium (LTE) and optical thin assumptions. It is clarified that line radiation is the dominant mechanism of PTFE plasma. The emission coefficient shows an opposite trend for both wavelength regions divided by 550 nm at a temperature above 15 000 K. The emission coefficient increases with increasing temperature and pressure. Furthermore, it has a good log linear relation with pressure. Equivalent emissivity varies complexly with temperature, and has a critical point between 20 000 K to 25 000 K. The equivalent cross points of the average ionic valence and radiation property are about 10 000 K and 15 000 K for fully single ionization.

Shielding data for hadron-therapy ion accelerators: Attenuation of secondary radiation in concrete

CERN Document Server

Agosteo, S; Sagia, E; Silari, M

2014-01-01

The secondary radiation field produced by seven different ion species (from hydrogen to nitrogen), impinging onto thick targets made of either iron or ICRU tissue, was simulated with the FLUKA Monte Carlo code, and transported through thick concrete shields: the ambient dose equivalent was estimated and shielding parameters evaluated. The energy for each ion beam was set in order to reach a maximum penetration in ICRU tissue of 290 mm (equivalent to the therapeutic range of 430 MeV/amu carbon ions). Source terms and attenuation lengths are given as a function of emission angle and ion species, along with fits to the Monte Carlo data, for shallow depth and deep penetration in the shield. Trends of source terms and attenuation lengths as a function of neutron emission angle and ion species impinging on tar- get are discussed. A comparison of double differential distributions of neutrons with results from similar simulation works reported in the literature is also included. The aim of this work is to provide shi...

Preparation, characterization and X-ray attenuation property of Gd2O3-based nanocomposites

Science.gov (United States)

Jayakumar, Sangeetha; Saravanan, T.; Philip, John

2017-11-01

In an attempt to develop an alternate to lead-based X-ray shielding material, we describe the X-ray attenuation property of nanocomposites containing Gd2O3 as nanofiller and silicone resin as matrix, prepared by a simple solution-casting technique. Gd2O3 nanoparticles of size 30 and 56 nm are used at concentrations of 25 and 2.5 wt%. The nanoparticles and the nanocomposites are characterized using X-ray diffraction (XRD) studies, small angle X-ray spectroscopy (SAXS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and atomic force microscopy (AFM). The X-ray attenuation property of nanocomposites, studied using an industrial X-ray unit, shows that nanocomposites containing nanoparticles of size 56 nm (G2) exhibit better attenuation than nanocomposites containing nanoparticles of size 30 nm (G1), which is attributed to the greater interfacial interaction between the G2 nanofillers and silicone matrix. In the case of nanocomposites containing G1 nanoparticles, the interfacial interaction between the nanofiller and the matrix is so weak that it results in pulling out of nanofillers, causing voids in the matrix, which act as X-ray transparent region, thereby reducing the overall X-ray attenuation property of G1 nanocomposites. This is further corroborated from the AFM images of the nanocomposites. The weight loss and heat flow curves of pure silicone matrix and the nanocomposites containing Gd2O3 nanoparticles of size 30 and 56 nm show the degradation of silicone resin, due to chain scission, between 403 and 622 °C. The same onset temperature (403 °C) of degradation of matrix with and without nanoparticles shows that the addition of nanofillers to the matrix does not deteriorate the thermal stability of the matrix. This confirms the thermal stability of nanocomposites. Therefore, our study shows that nanocomposites containing G2 nanoparticles are potential candidates for the development of X-ray opaque fabric material.

Transient attenuation in optical fibers

International Nuclear Information System (INIS)

Hopkins, A.A.; Kelly, R.E.; Looney, L.D.; Lyons, P.B.

1984-01-01

Low and high energy pulsed electron beams were used to generate radiation-induced transient attenuation in high-OH, Suprasil core, PCS fibers, demonstrating the energy dependence of the radiation damage and recovery mechanisms. A radiation resistant low-OH fiber was studied and its performance contrasted to that of high-OH materials. Several fibers with differing core compositions were also studied

Radiation modification of the properties of polypropylene ...

Indian Academy of Sciences (India)

Research and Technology, Atomic Energy Authority, P.O. Box 29, Nasr City, Egypt. 2Radiation ... tions such as radiation sterilized medical and pharmaceutical ... extensively studied to extend the shelf life of food prod- ucts. ..... ond step is in the range of 210–305 ... effect of radiation on the thermal properties of PP/15wt%.

Method for evaluation of radiative properties of glass samples

Energy Technology Data Exchange (ETDEWEB)

Mohelnikova, Jitka [Faculty of Civil Engineering, Brno University of Technology, Veveri 95, 602 00 Brno (Czech Republic)], E-mail: mohelnikova.j@fce.vutbr.cz

2008-04-15

The paper presents a simple calculation method which serves for an evaluation of radiative properties of window glasses. The method is based on a computer simulation model of the energy balance of a thermally insulated box with selected glass samples. A temperature profile of the air inside of the box with a glass sample exposed to affecting radiation was determined for defined boundary conditions. The spectral range of the radiation was considered in the interval between 280 and 2500 nm. This interval is adequate to the spectral range of solar radiation affecting windows in building facades. The air temperature rise within the box was determined in a response to the affecting radiation in the time between the beginning of the radiation exposition and the time of steady-state thermal conditions. The steady state temperature inside of the insulated box serves for the evaluation of the box energy balance and determination of the glass sample radiative properties. These properties are represented by glass characteristics as mean values of transmittance, reflectance and absorptance calculated for a defined spectral range. The data of the computer simulations were compared to experimental measurements on a real model of the insulated box. Results of both the calculations and measurements are in a good compliance. The method is recommended for preliminary evaluation of window glass radiative properties which serve as data for energy evaluation of buildings.

Ambient ultraviolet radiation induces protective responses in soybean but does not attenuate indirect defense

Energy Technology Data Exchange (ETDEWEB)

Winter, Thorsten R. [Department of Botany II, Julius-von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 3, 97082 Wuerzburg (Germany); Rostas, Michael [Department of Botany II, Julius-von-Sachs Institute for Biosciences, University of Wuerzburg, Julius-von-Sachs-Platz 3, 97082 Wuerzburg (Germany)], E-mail: rostas@botanik.uni-wuerzburg.de

2008-09-15

We investigated the effects of ambient ultraviolet (UV) radiation on (i) the performance and chemistry of soybean plants, (ii) the performance of Spodoptera frugiperda and (iii) the foraging behavior of the herbivore's natural enemy Cotesia marginiventris which exploits herbivore-induced plant volatiles (VOC) for host location. The accumulation of protective phenolics was faster in plants receiving ambient UV than in controls exposed to sun light lacking UV. Accordingly, isorhamnetin- and quercetin-based flavonoids were increased in UV exposed plants. No UV effects were found on the performance and feeding behavior of S. frugiperda. Herbivore-damaged plants emitted the same VOC when grown under ambient or attenuated UV for 5, 10 or 30 days. Consequently, C. marginiventris was attracted but did not discriminate between exposed and unexposed soybeans. In summary, ambient UV radiation affected soybean morphology and physiology but did not destabilize interactions between trophic levels. - Ambient ultraviolet radiation does not alter induced VOC emission in soybean and thus host location of the parasitoid Cotesia marginiventris remains effective.

Radiation-induced attenuation in polarization maintaining fibers: low dose rate response, stress, and materials effects

International Nuclear Information System (INIS)

Gingerich, M.E.; Friebele, E.J.; Hickey, S.J.; Brambani, L.A.; Onstott, J.R.

1989-01-01

The loss induced in polarization-maintaining (PM) fibers by low dose rate <0.01 Gy/h, where 1 Gy = 100 rads(Si) radiation exposure has been found to vary from <0.4 to ∼6 dB/km-10 Gy, depending on the wavelength of measurement and the fiber. Correlations have been established between low dose rate response and the ''permanent'' induced loss determined by fitting the recovery of the induced loss following high dose rate exposure to nth-order kinetics. Using this technique, both 0.85- and 1.3-μm PM fibers have been found which show virtually no permanent incremental loss and would therefore appear to be resistant to low dose rate radiation environments. The asymmetric stress inherent in PM fibers has been shown to reduce the permanent induced loss, while the recovery of the radiation-induced attenuation was found to be enhanced in fibers with Ge-F-doped silica clads

Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

Energy Technology Data Exchange (ETDEWEB)

Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Shiraishi, Takahiro [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Suga, Mikio [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Center for Frontier Medical Engineering, Chiba University (Japan); Obata, Takayuki [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan); Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Chiba (Japan); Ito, Hiroshi; Yamaya, Taiga [Molecular Imaging Center, National Institute of Radiological Sciences, Chiba (Japan)

2014-07-29

In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

Optimization of transmission-scan time for the FixER method: a MR-based PET attenuation correction with a weak fixed-position external radiation source

International Nuclear Information System (INIS)

Kawaguchi, Hiroshi; Hirano, Yoshiyuki; Kershaw, Jeff; Yoshida, Eiji; Shiraishi, Takahiro; Suga, Mikio; Obata, Takayuki; Ito, Hiroshi; Yamaya, Taiga

2014-01-01

In recent work, we proposed an MRI-based attenuation-coefficient (μ-value) estimation method that uses a weak fixed-position external radiation source to construct an attenuation map for PET/MRI. In this presentation we refer to this method as FixER, and perform a series of simulations to investigate the duration of the transmission scan required to accurately estimate μ-values.

Study of material properties using channeling radiation

International Nuclear Information System (INIS)

Pantell, R.H.; Kephart, J.O.; Klein, R.K.; Park, H.; Berman, B.L.; Datz, S.

1986-01-01

A possible application for channeling radiation is for investigating the properties of crystals in which the channeling occurs. In this paper we present some general considerations concerning channeling radiation as a measurement technique, and then we proceed to describe several specific examples

Characterization of barite and crystal glass as attenuators in X-ray and gamma radiation shieldings

International Nuclear Information System (INIS)

Almeida Junior, Airton Tavares de

2005-03-01

Aiming to determine the barium sulphate (BaSO 4 ) ore and crystal glass attenuation features, both utilized as shieldings against ionizing X and gamma radiations in radiographic installations, a study of attenuation using barite plaster and barite concrete was carried out, which are used, respectively, on wall coverings and in block buildings. The crystal glass is utilized in screens and in windows. To do so, ten plates of barite plaster and three of barite concrete with 900 cm 2 and with an average thickness ranging from 1 to 5 cm, and three plates of crystal glass with 323 cm 2 and with thicknesses of 1, 2 and 4 cm were analyzed. The samples were irradiated with X-rays with potentials of 60, 80, 110 and 150 kilovolts, and also with 60 Co gamma rays. Curves of attenuation were obtained for barite plaster and barite concrete (mGy/mA.min) and (mGy/h), both at 1 meter, as a function of thickness and curve of transmission through barite plaster and barite concrete as a function of the thickness. The equivalent thicknesses of half and tenth value layers for barite plaster, barite concrete and crystal glass for all X-Ray energies were also determined. (author)

Computer modelling of statistical properties of SASE FEL radiation

International Nuclear Information System (INIS)

Saldin, E. L.; Schneidmiller, E. A.; Yurkov, M. V.

1997-01-01

The paper describes an approach to computer modelling of statistical properties of the radiation from self amplified spontaneous emission free electron laser (SASE FEL). The present approach allows one to calculate the following statistical properties of the SASE FEL radiation: time and spectral field correlation functions, distribution of the fluctuations of the instantaneous radiation power, distribution of the energy in the electron bunch, distribution of the radiation energy after monochromator installed at the FEL amplifier exit and the radiation spectrum. All numerical results presented in the paper have been calculated for the 70 nm SASE FEL at the TESLA Test Facility being under construction at DESY

Measurement of X-ray mass attenuation coefficient of nickel around the K-edge using synchrotron radiation based X-ray absorption study

International Nuclear Information System (INIS)

Roy, Bunty Rani; Rajput, Parasmani; Jha, S.N.; Nageswara Rao, A.S.

2015-01-01

The work presents the X-ray absorption fine structure (XAFS) technique for measuring the X-ray mass attenuation coefficient of nickel metal foil in the X-ray energy range of 8271.2–8849.4 eV using scanning XAFS beam line (BL-09) at Indus-2 synchrotron radiation source facility, Raja Ramanna Centre for Advanced Technology (RRCAT) at Indore, India. The result represents the X-ray mass attenuation coefficient data for 0.02 mm thick Ni metal foil in the XAFS region of Ni K-edge. However, the results are compared to theoretical values using X-COM. There is a maximum deviation which is found exactly near the K-edge jump and decreases as we move away from the absorption edge. Oscillatory structure appears just above the observed absorption edge i.e., 8348.7 eV and is confined to around 250 eV above the edge. - Highlights: • Mass attenuation coefficient measurements of nickel using synchrotron radiation. • The measurements were taken exactly near the Ni K-edge at an energy step of 1 eV. • A maximum deviation is found near the K-edge

Cryopreservation and distribution of radiation-attenuated helminth larvae and the use of radioisotopes to monitor their survival. Coordinated programme on preparation of irradiated vaccines against some human diseases

International Nuclear Information System (INIS)

James, E.

1982-06-01

Techniques for the cryopreservation of schistosomula are described, from the methanol/two-step cooling technique, through a technique which uses 40% methanol and rapid cooling to the current technique which employs a two-step addition of ethanediol and rapid cooling. Levels of survival with these techniques have improved from 0.3% to 5.9% and now to 47% of control values. The 40% methanol/rapid cooling technique is described in detail as this forms the basis for understanding the role of cryoprotective additives and cooling and warming rates in the cryopreservation of schistosomula. The toxicity of 12 different potentially cryoprotective compounds is described. Cryopreservation of S.japonicum and S.bovis is described. The effect of the age of the schistosomula and their cryopreservability is related to the development of water sensitivity and the permeation and damage produced by glycerol and it is postulated that morphological changes occurring in the tegument during transformation from a cercaria to schistosomulum may account for these observations. Studies with 14 C-ethanediol are described which attempt to provide an understanding of permeability of cryoprtectants to schistosomula of different ages and at different temperatures. Vaccination studies with cryopreserved and radiation-attenuated schistosomula are also reported. Radiation-attenuated schistosomula are also reported. Radiation-attenuated cercariae and schistosomula produced high (64% to 89%) levels of protection in baboons, and cryopreserved schistosomula produced comparable levels of protection in vaccinated mice to normal schistosomula. Cryopreserved radiation-attenuated schistosomula produced a significant level of protection (49% reduction) in sheep although the numbers of normally motile organisms injected was low (1,000 per dose, 2 doses). It is concluded that normally-motile cryopreserved radiation-attenuated schistosomula are as immunogenic as fresh organisms

Experimental immunization of ponies with Strongylus vulgaris radiation-attenuated larvae or crude soluble somatic extracts from larval or adult stages.

Science.gov (United States)

Monahan, C M; Taylor, H W; Chapman, M R; Klei, T R

1994-12-01

Protection from Strongylus vulgaris infection through immunization with radiation-attenuated third-stage larvae (L3) or crude soluble homogenates from larval or adult stages was examined. Yearling ponies raised parasite-free were divided into 3 immunization groups: radiation-attenuated L3; soluble adult somatic extracts; larval somatic extracts with excretory/secretory products (E/S) from in vitro culture; and 1 medium control group. Ponies were immunized twice; attenuated larvae were administered orally and somatic extracts or controls injected intramuscularly with adjuvant. Approximately 6 wk following the second immunization, all ponies were challenged. Necrospy examinations were performed 6 wk following challenge. Irradiated larvae recipients had the fewest postchallenge clinical signs and lesions and were 91% protected from infection determined by larval recoveries from arterial dissections. Soluble antigen recipients and controls had similar larval recoveries and thus equal susceptibility to challenge. Soluble antigen recipients had more severe clinical signs and lesions than controls, suggesting that parenteral immunization exacerbated postchallenge inflammatory responses. Protection by immunization with irradiated larvae was associated with an anamnestic eosinophilia and postimmunization antibody recognition of S. vulgaris L3 surface antigens. Histologic staining of eosinophils within tissues of this group suggested that this immunization induced a cytophilic antibody response that facilitated degranulation.

Thermal, epithermal and thermalized neutron attenuation properties of ilmenite-serpentine heat resistant concrete shield

International Nuclear Information System (INIS)

Kany, A.M.I.; El-Gohary, M.I.; Kamal, S.M.

1994-01-01

Experimental measurements were carried out to study the attenuation properties of low-energy neutrons transmitted through unheated and preheated barriers of heavy-weight, highly hydrated and heat-resistant concrete shields. The concrete shields under investigation have been prepared from naturally occurring ilmenite and serpentine Egyptian ores. A collimated beam obtained from an Am-Be source was used as a source of neutrons, while the measurements of total thermal, epithermal, and thermalized neutron fluxes were performed using a BF-3 detector, multichannel analyzer and Cd filter. Results show that the ilmenite-serpentine concrete proved to be a better thermal, epithermal and thermalized neutron attenuator than the ordinary concrete especially at a high temperature of concrete exposure. (Author)

Asymptotic stability and disturbance attenuation properties for a class of networked control systems

Institute of Scientific and Technical Information of China (English)

无

2006-01-01

In this paper, stability and disturbance attenuation issues for a class of Networked Control Systems (NCSs)under uncertain access delay and packet dropout effects are considered. Our aim is to find conditions on the delay and packet dropout rate, under which the system stability and H∞ disturbance attenuation properties are preserved to a desired level. The basic idea in this paper is to formulate such Networked Control System as a discrete-time switched system. Then the NCSs' stability and performance problems can be reduced to the corresponding problems for switched systems, which have been studied for decades and for which a number of results are available in the literature. The techniques in this paper are based on recent progress in the discrete-time switched systems and piecewise Lyapunov functions.

Millimetre wave attenuation of prototype diagnostic components for the ITER bolometers

Energy Technology Data Exchange (ETDEWEB)

Meister, H., E-mail: meister@ipp.mpg.de [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Kasparek, W. [Universität Stuttgart, Institut für Grenzflächenverfahrenstechnik & Plasmatechnologie, Stuttgart (Germany); Zhang, D.; Hirsch, M. [Max-Planck-Institut für Plasmaphysik, Teilinstitut Greifswald, Greifswald (Germany); Koll, J. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Zeitler, A. [Universität Stuttgart, Institut für Grenzflächenverfahrenstechnik & Plasmatechnologie, Stuttgart (Germany)

2015-10-15

Highlights: • Attenuation of ECRH stray radiation in ITER demonstrated for bolometer prototypes. • Collimator with microwave reflecting grid achieves >70 dB at 170 GHz (ITER frequency). • For frequencies >250 GHz (ECE radiation) ceramic coating showed 40 dB attenuation. • Good shielding at joints of components is prerequisite to prevent microwave leakage. • These methods prevent the impact of ECRH stray radiation on bolometer measurements. - Abstract: Bolometers in current and future fusion devices, in particular those in ITER, are vulnerable to stray radiation from electron cyclotron resonance heating (ECRH) which results in measurement errors for plasma radiation detection. To protect the detectors from this stray radiation in the millimetre wavelength range, dedicated diagnostic components have been designed and tested. One option is to place a top plate which contains a microwave-reflecting grid onto the collimators. Another option investigated is the coating of the collimator channels using a microwave absorbing ceramic. Measurements of the mm-wave attenuation of the collimator in front of the bolometer detectors with and without top plate or coated collimator channels have been performed in the frequency range of 125–420 GHz. The attenuation factor of the collimator channels at 170 GHz (the ECRH frequency for ITER) with neither microwave grid nor coating is typically 10 dB. The coating enhances this to 40 dB and including the microwave grid yields at least an attenuation factor of 70 dB, which is sufficient to reduce the residual ECRH induced signal significantly below the one due to plasma radiation. Placing a bolometer camera (collimator connected to detector housing) inside the isotropic microwave field of the test facility MISTRAL, the attenuation factor of the full diagnostic set-up using a top plate was determined to be in the order of 45 dB. This degraded attenuation implies that particular attention has to be paid to design and quality

Attenuation coefficients of soils

International Nuclear Information System (INIS)

Martini, E.; Naziry, M.J.

1989-01-01

As a prerequisite to the interpretation of gamma-spectrometric in situ measurements of activity concentrations of soil radionuclides the attenuation of 60 to 1332 keV gamma radiation by soil samples varying in water content and density has been investigated. A useful empirical equation could be set up to describe the dependence of the mass attenuation coefficient upon photon energy for soil with a mean water content of 10%, with the results comparing well with data in the literature. The mean density of soil in the GDR was estimated at 1.6 g/cm 3 . This value was used to derive the linear attenuation coefficients, their range of variation being 10%. 7 figs., 5 tabs. (author)

Radiative properties of ice clouds

Energy Technology Data Exchange (ETDEWEB)

Mitchell, D.L.; Koracin, D.; Carter, E. [Desert Research Institute, Reno, NV (United States)

1996-04-01

A new treatment of cirrus cloud radiative properties has been developed, based on anomalous diffraction theory (ADT), which does not parameterize size distributions in terms of an effective radius. Rather, is uses the size distribution parameters directly, and explicitly considers the ice particle shapes. There are three fundamental features which characterize this treatment: (1) the ice path radiation experiences as it travels through an ice crystal is parameterized, (2) only determines the amount of radiation scattered and absorbed, and (3) as in other treatments, the projected area of the size distribution is conserved. The first two features are unique to this treatment, since it does not convert the ice particles into equivalent volume or area spheres in order to apply Mie theory.

Light attenuation in estuarine mangrove lakes

Science.gov (United States)

Frankovich, Thomas A.; Rudnick, David T.; Fourqurean, James W.

2017-01-01

Submerged aquatic vegetation (SAV) cover has declined in brackish lakes in the southern Everglades characterized by low water transparencies, emphasizing the need to evaluate the suitability of the aquatic medium for SAV growth and to identify the light attenuating components that contribute most to light attenuation. Underwater attenuation of downwards irradiance of photosynthetically active radiation (PAR) was determined over a three year period at 42 sites in shallow (freshwater flow into these areas may dilute CDOM concentrations and improve the salinity and light climate for SAV communities.

Altered patterns of gene expression underlying the enhanced immunogenicity of radiation-attenuated schistosomes.

Directory of Open Access Journals (Sweden)

Gary P Dillon

2008-05-01

Full Text Available Schistosome cercariae only elicit high levels of protective immunity against a challenge infection if they are optimally attenuated by exposure to ionising radiation that truncates their migration in the lungs. However, the underlying molecular mechanisms responsible for the altered phenotype of the irradiated parasite that primes for protection have yet to be identified.We have used a custom microarray comprising probes derived from lung-stage parasites to compare patterns of gene expression in schistosomula derived from normal and irradiated cercariae. These were transformed in vitro and cultured for four, seven, and ten days to correspond in development to the priming parasites, before RNA extraction. At these late times after the radiation insult, transcript suppression was the principal feature of the irradiated larvae. Individual gene analysis revealed that only seven were significantly down-regulated in the irradiated versus normal larvae at the three time-points; notably, four of the protein products are present in the tegument or associated with its membranes, perhaps indicating a perturbed function. Grouping of transcripts using Gene Ontology (GO and subsequent Gene Set Enrichment Analysis (GSEA proved more informative in teasing out subtle differences. Deficiencies in signalling pathways involving G-protein-coupled receptors suggest the parasite is less able to sense its environment. Reduction of cytoskeleton transcripts could indicate compromised structure which, coupled with a paucity of neuroreceptor transcripts, may mean the parasite is also unable to respond correctly to external stimuli.The transcriptional differences observed are concordant with the known extended transit of attenuated parasites through skin-draining lymph nodes and the lungs: prolonged priming of the immune system by the parasite, rather than over-expression of novel antigens, could thus explain the efficacy of the irradiated vaccine.

Evaluation of the vibration attenuation properties of an air-inflated cushion with two different heavy machinery seats in multi-axis vibration environments including jolts.

Science.gov (United States)

Ji, Xiaoxu; Eger, Tammy R; Dickey, James P

2017-03-01

Seats and cushions can attenuate whole-body vibration (WBV) exposures and minimize health risks for heavy machine operators. We successfully developed neural network (NN) algorithms to identify the vibration attenuation properties for four different seating conditions (seat/cushion combinations), and implemented each of the NN models to predict the equivalent daily exposure A(8) values for various vehicles in the forestry and mining environments. We also evaluated the performance of the new prototype No-Jolt™ air-inflated cushion and the original cushion of each seat with jolt exposures. We observed that the air cushion significantly improved the vibration attenuation properties of the seat that initially had good performance, but not for the seat that had relatively poor vibration attenuation properties. In addition, operator's anthropometrics and sex influenced the performance of the air-inflated cushion when the vibration environment included jolt exposures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment of vaccination with schistosomules attenuated by using different doses of γ-radiation on experimental schistosomiasis mansoni

International Nuclear Information System (INIS)

Mohamed, E.N.H.

2009-01-01

Current strategies for the control of schistosomiasis are based primarily on chemotherapy but successful vaccination against infection has been also demonstrated in several host parasite models.The present study was designed to asses the immunogenic effects of the vaccination with autogenic targets in the form of schistosomula attenuated by different doses of γ-radiation (15, 20, 25 kilo rad) in mice challenged with S. mansoni cercariae as regard parasitological, histological, biochemical and immunological aspects.

Neutron shielding properties of a borated high-density glass

Directory of Open Access Journals (Sweden)

Saeed Aly Abdallah

2017-01-01

Full Text Available The neutron shielding properties of a borated high density glass system was characterized experimentally. The total removal macroscopic cross-section of fast neutrons, slow neutrons as well as the linear attenuation coefficient of total gamma rays, primary in addition to secondary, were measured experimentally under good geometric condition to characterize the attenuation properties of (75-x B2O3-1Li2O-5MgO-5ZnO-14Na2O-xBaO glassy system. Slabs of different thicknesses from the investigated glass system were exposed to a collimated beam of neutrons emitted from 252Cf and 241Am-Be neutron sources in order to measure the attenuation properties of fast and slow neutrons as well as total gamma rays. Results confirmed that barium borate glass was suitable for practical use in the field of radiation shielding.

Radiation-optical properties of the glasses for the space application

International Nuclear Information System (INIS)

Akishin, A.I.; Tseplyaev, L.I.

2006-01-01

The data are presented and generalized on variations of optical properties of glass and light guides under simulative cosmic ionizing radiation. It is shown that changes in optical properties (coloration, bleaching, opacity, luminescence) under ionizing radiation are associated with color centers formation and annealing [ru

Wheat Germ Oil Attenuates Gamma Radiation- Induced Skeletal Muscles Damage in Rats

International Nuclear Information System (INIS)

Said, U.Z.; Saada, H.N.; Shedid, Sh.M.; Mahdy, E.M.E.; Shousha, W.Gh.

2008-01-01

Muscular strength is important in sport as well as in daily activities. Exposure to ionizing radiation is thought to increase oxidative stress and damage muscle tissue. Wheat germ oil is a natural unrefined vegetable oil. It is an excellent source of vitamin E, octacosanol, linoleic and linolenic essential fatty acids, which may be beneficial in neutralizing the free oxygen radicals. The present study was designed to investigate the efficacy of wheat germ oil, on radiation-induced oxidative damage in rats skeletal muscle. Wheat germ oil was supplemented orally via gavages to rats at a dose of 54 mg/ kg body weight/day for 14 successive days pre- and 7 post-exposure to 5 Gy (one shot dose) of whole body gamma irradiation. Animals were sacrificed 7, 14 and 21 days post radiation exposure. The results revealed that whole body gamma-irradiation of rats induces oxidative stress in skeletal muscles obvious by significant elevation in the level of thiobarbituric acid reactive substances (TBARS) associated with significant decreases in the content of reduced glutathione (GSE1), as well as decreases in superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) activities. Irradiated rats showed, also, significant decreases in creatine phosphokinase (CPK), glutamate dehydrogenase (GDH) and glucose-6-phosphate dehydrogenase (G-6-PD) activities. Furthermore, total iron, total copper and total calcium levels were significantly increased in skeletal muscles of irradiated rats group compared to control group. Wheat germ oil treated-irradiated rats showed significantly less sever damage and remarkable improvement in all the measured parameters, compared to irradiated rats. It could be concluded that wheat germ oil by attenuating radiation induced oxidative stress might play a role in maintaining skeletal muscle integrity

18-year variability of ultraviolet radiation penetration in the mid-latitude coastal waters of the western boundary Pacific

Science.gov (United States)

Kuwahara, Victor S.; Nozaki, Sena; Nakano, Junji; Toda, Tatsuki; Kikuchi, Tomohiko; Taguchi, Satoru

2015-07-01

The 18-year time-series shows in situ ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) diffuse attenuation coefficient Kd(λ) have recurrent seasonal variability of high/low attenuation during summer/winter months, respectively, dependent on variability in water column stratification and concentrations of bio-optical properties. The mid-latitude coastal survey station displayed significant seasonality of the mixed layer depth (MLD) between 12 and 82 m which modified the distribution of chlorophyll a (4.6-24.9 mg m-2) and absorption of colored dissolved organic matter [aCDOM(320 nm) 0.043-1.34 m-1]. The median Kd(320 nm) displayed significant seasonality at 0.19-0.74 m-1 (C.V. = 44.1%) and seasonal variability within the euphotic layer [Z10%(320 nm) = 7-20%]. High attenuation of UVR with relatively moderate attenuation of PAR was consistently observed during the summer months when increased concentrations of terrestrially derived CDOM coupled with a shallow MLD were present. The winter season showed the opposite of low UVR and PAR attenuation due to a relatively deeper MLD coupled with low concentrations of bio-optical properties. Although the long term Kd(λ) did not vary significantly during the time-series, analysis of the interannual variability suggests there are positive and negative phases following the Pacific Decadal Oscillation (PDO) vis-a-vis variability in bio-optical properties (p < 0.001).

Radiation Shielding Properties of Some Marbles in Turkey

International Nuclear Information System (INIS)

Guenoglu, K.; Akkurt, I.

2011-01-01

Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazardous effect of radiation into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined.In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.

Impact of UV radiation on the physical properties of polypropylene ...

African Journals Online (AJOL)

The purpose of this study was to analyse the influence of simulated sun light radiation (xenon lamp) on physical properties of polypropylene (PP) nonwoven material, which is used for the production of agrotextiles. The research showed that the properties of row cover change when radiated with UV light. Tensile, tearing ...

Heat-accelerated radioinactivation of attenuated poliovirus

International Nuclear Information System (INIS)

Dugan, V.L.; Trujillo, R.

1975-01-01

Attenuated poliovirus is inactivated in a synergistic manner when exposed simultaneously to heat and ionizing radiation. The synergistic response is observed in both the thermally labile and stable forms of the virus. A three-term kinetic model may be used to describe the inactivation response of the virus in a thermal and/or ionizing radiation environment. (orig.) [de

The influence of body mass index and gender on the impact attenuation properties of flooring systems.

Science.gov (United States)

Bhan, Shivam; Levine, Iris; Laing, Andrew C

2013-12-01

The biomechanical effectiveness of safety floors has never been assessed during sideways falls with human volunteers. Furthermore, the influence of body mass index (BMI) and gender on the protective capacity of safety floors is unknown. The purpose of this study was to test whether safety floors provide greater impact attenuation compared with traditional flooring, and whether BMI and gender modify their impact attenuation properties. Thirty participants (7 men and 7 women of low BMI; 7 men and 9 women of high BMI) underwent lateral pelvis release trials on 2 common floors and 4 safety floors. As a group, the safety floors reduced peak force (by up to 11.7%), and increased the time to peak force (by up to 25.5%) compared with a traditional institutional grade floor. Force attenuation was significantly higher for the low BMI group, and for males. Force attenuation was greatest for the low BMI males, averaging 26.5% (SD = 3.0) across the safety floors. These findings demonstrate an overall protective effect of safety floors during lateral falls on the pelvis, but also suggest augmented benefits for frail older adults (often with low body mass) who are at an increased risk of hip fracture.

Oesophagostomum columbianum : immunization of young lambs using gamma ray attenuated inefective larvae

International Nuclear Information System (INIS)

Sharma, R.L.; Dhar, D.N.

1987-01-01

Infective Oesophagostomum columbianum larvae were successfully attenuated by exposing them to a gamma radiation dose levels of either 40 or 50 Krad. Lambs receiving a single vaccination dose of 2000 infective larvae attenuated at 40 Krad developed partial protection, whereas those vaccinated with similar dose of infection with 50 Krad irradiated larvae failed to develop any protection. A double vaccination schedule comprising of 500 and 2000 gamma attenuated (40 Krad) infective larvae induced a significantly higher level of protection against the challenge dose. The possible use of radiation attenuated larvae as vaccine for immunoprophylaxis against ovine Oesophagostomiasis has been discussed. (author). 11 refs., 2 tables

Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

Energy Technology Data Exchange (ETDEWEB)

Mahmud, Maznah [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia); Daik, Rusli [School of Chemical Sciences and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia 43600 Bangi, Selangor (Malaysia); Adam, Zainah [Radiation Processing Technology Division, Malaysian Nuclear Agency, 43000 Kajang, Selangor (Malaysia)

2015-09-25

Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

Attenuation in Superconducting Circular Waveguides

Directory of Open Access Journals (Sweden)

K. H. Yeap

2016-09-01

Full Text Available We present an analysis on wave propagation in superconducting circular waveguides. In order to account for the presence of quasiparticles in the intragap states of a superconductor, we employ the characteristic equation derived from the extended Mattis-Bardeen theory to compute the values of the complex conductivity. To calculate the attenuation in a circular waveguide, the tangential fields at the boundary of the wall are first matched with the electrical properties (which includes the complex conductivity of the wall material. The matching of fields with the electrical properties results in a set of transcendental equations which is able to accurately describe the propagation constant of the fields. Our results show that although the attenuation in the superconducting waveguide above cutoff (but below the gap frequency is finite, it is considerably lower than that in a normal waveguide. Above the gap frequency, however, the attenuation in the superconducting waveguide increases sharply. The attenuation eventually surpasses that in a normal waveguide. As frequency increases above the gap frequency, Cooper pairs break into quasiparticles. Hence, we attribute the sharp rise in attenuation to the increase in random collision of the quasiparticles with the lattice structure.

Attenuation-based kV pair selection in dual source dual energy computed tomography angiography of the chest: impact on radiation dose and image quality

Energy Technology Data Exchange (ETDEWEB)

Renapurkar, Rahul D.; Azok, Joseph; Lempel, Jason; Karim, Wadih; Graham, Ruffin [Thoracic Imaging, L10, Imaging Institute, Cleveland Clinic, Cleveland, OH (United States); Primak, Andrew [Siemens Medical Solutions, Malvern, PA (United States); Tandon, Yasmeen [Case Western Reserve University-Metro Health Medical Center, Department of Radiology, Cleveland, OH (United States); Bullen, Jennifer [Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH (United States); Dong, Frank [Section of Medical Physics, Cleveland Clinic, Cleveland, OH (United States)

2017-08-15

The purpose of this study was to evaluate the impact of attenuation-based kilovoltage (kV) pair selection in dual source dual energy (DSDE)-pulmonary embolism (PE) protocol examinations on radiation dose savings and image quality. A prospective study was carried out on 118 patients with suspected PE. In patients in whom attenuation-based kV pair selection selected the 80/140Sn kV pair, the pre-scan 100/140Sn CTDIvol (computed tomography dose index volume) values were compared with the pre-scan 80/140Sn CTDIvol values. Subjective and objective image quality parameters were assessed. Attenuation-based kV pair selection switched to the 80/140Sn kV pair (''switched'' cohort) in 63 out of 118 patients (53%). The mean 100/140Sn pre-scan CTDIvol was 8.8 mGy, while the mean 80/140Sn pre-scan CTDIvol was 7.5 mGy. The average estimated dose reduction for the ''switched'' cohort was 1.3 mGy (95% CI 1.2, 1.4; p < 0.001), representing a 15% reduction in dose. After adjusting for patient weight, mean attenuation was significantly higher in the ''switched'' vs. ''non-switched'' cohorts in all five pulmonary arteries and in all lobes on iodine maps. This study demonstrates that attenuation-based kV pair selection in DSDE examination is feasible and can offer radiation dose reduction without compromising image quality. (orig.)

Radiation Shielding Properties of Some Marbles in Turkey

Science.gov (United States)

Günoǧlu, K.; Akkurt, I.

2011-12-01

Especially after development of technology, radiation started to be used in a large fields such as medicine, industry and energy. Using radiation in those fields bring hazordous effect of radition into humancell. Thus radiation protection becomes important in physics. Although there are three ways for radiation protection, shielding of the radiation is the most commonly used method. Natural Stones such as marble is used as construction material especially in critical building and thus its radiation shielding capability should be determined. In this study, gamma ray shielding properties of some different types of marble mined in Turkey, have been measured using a NaI(Tl) scintillator detector. The measured results were also compared with the theoretical calculations XCOM.

High Density Radiation Shielding Concretes for Hot Cells of 99mTc Project

International Nuclear Information System (INIS)

Sakr, K.

2006-01-01

High density concrete [more than 3.6 ton/m 3 (3.6x10 3 kg/m 3 )] was prepared to be used as a radiation shielding concrete (RSC) for hot-cells in gel technetium project at inshas to attenuate gamma radiation emitted from radioactive sources. different types of concrete were prepared by mixing local mineral aggregates mainly gravel and ilmenite . iron shots were added to the concrete mixture proportion as partial replacement of heavy aggregates to increase its density. the physical properties of prepared concrete in both plastic and hardened phases were investigated. compressive strength and radiation attenuation of gamma rays were determined. Results showed that ilmenite concrete mixed with iron shots had the highest density suitable to be use as RSC according to the chinese hot cell design requirements. Recommendations to avoid some technical problems of manufacturing radiation shielding concrete were maintained

Coherence properties of the radiation from FLASH

International Nuclear Information System (INIS)

Schneidmiller, E.A.; Yurkov, M.V.

2015-02-01

FLASH is the first free electron laser user facility operating in the vacuum ultraviolet and soft x-ray wavelength range. Many user experiments require knowledge of the spatial and temporal coherence properties of the radiation. In this paper we present an analysis of the coherence properties of the radiation for the fundamental and for the higher odd frequency harmonics. We show that temporal and spatial coherence reach maximum close to the FEL saturation but may degrade significantly in the post-saturation regime. We also find that the pointing stability of short FEL pulses is limited due to the fact that non-azimuthal FEL eigenmodes are not sufficiently suppressed. We discuss possible ways for improving the degree of transverse coherence and the pointing stability.

Attenuation properties of radiation shielding materials such as granite and marble against γ-ray energies between 80 and 1350 keV

Energy Technology Data Exchange (ETDEWEB)

Eke, Canel [Akdeniz Univ., Antalya (Turkey). Nuclear Sciences Application and Research Center; Akdeniz Univ., Antalya (Turkey). Div. of Physics Education; Agar, Osman [Akdeniz Univ., Antalya (Turkey). Nuclear Sciences Application and Research Center; Karamanoglu Mehmetbey Univ., Karaman (Turkey). Dept. of Physics; Segebade, Christian [Akdeniz Univ., Antalya (Turkey). Nuclear Sciences Application and Research Center; Boztosun, Ismail [Akdeniz Univ., Antalya (Turkey). Nuclear Sciences Application and Research Center; Akdeniz Univ., Antalya (Turkey). Dept. of Physics

2017-07-01

In this study, the γ-ray energy-dependent mass and linear attenuation coefficients of various granite and Turkish marble species have been experimentally obtained. Radionuclides ({sup 133}Ba, {sup 137}Cs, {sup 60}Co and {sup 22}Na) with point geometry were used as γ-ray sources. The absorption capacity of each sample at nine γ-ray energies was measured using a high resolution γ-ray spectrometer equipped with a high purity germanium (HPGe) detector. To obtain the precision of the results (1σ standard deviation of the single value), this procedure was repeated six times for each species of granite and marble, respectively. The energy-dependent mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), the half (HVL) and the tenth value layer (TVL) were calculated following that the MAC and LAC results were compared to the literature values.

Thermomechanical properties of radiation hardened oligoesteracrylates

International Nuclear Information System (INIS)

Lomonosova, N.V.; Chikin, Yu.A.

1984-01-01

Thermomechanical properties of radiation hardened oligoesteracrylates are studied by the methods of isothermal heating and thermal mechanics. Films of dimethacrylate of ethylene glycol, triethylene glycol (TGM-3), tetraethylene glycol, tridecaethylene glycol and TGM-3 mixture with methyl methacrylate hardened by different doses (5-150 kGy) using Co 60 installation with a dose rate of 2x10 -3 kGy/s served as a subject of the research. During oligoesteracrylate hargening a space network is formed, chain sections between lattice points of which are in a stressed state. Maximum of deformation is observed at 210-220 deg C on thermomechanical curves of samples hardened by doses > 5 kGy, which form and intensity is dependent on an absorbed dose. Presence of a high-temperature maximum on diaqrams of isometric heating of spatially cross-linked oligoesteracrylates is discovered. High thermal stability of three-dimensional network of radiation hardened oligoesteracrylates provides satisfactory tensile properties (40% of initial strength) in sample testing an elevated temperatures (200-250 deg C)

Study of mass attenuation coefficients and effective atomic numbers of bismuth-ground granulated blast furnace slag concretes

International Nuclear Information System (INIS)

Kumar, Sandeep; Singh, Sukhpal

2016-01-01

Five samples of Bismuth-Ground granulated blast furnace slag (Bi-GGBFS) concretes were prepared using composition (0.6 cement + x Bi_2O_3 + (0.4-x) GGBFS, x = 0.05, 0.10, 0.15, 0.20 and 0.25) by keeping constant water (W) cement (C) ratio. Mass attenuation coefficients (μ_m) of these prepared samples were calculated using a computer program winXCOM at different gamma ray energies, whereas effective atomic numbers (Z_e_f_f) is calculated using mathematical formulas. The radiation shielding properties of Bi-GGBFS concrete has been compared with standard radiation shielding concretes.

An experimental study of the shielding characteristics of the dwelling house building materials against gamma radiations in the Central Region of Syria

International Nuclear Information System (INIS)

Albarhoum, M.; Soufan, A.H.; Mustafa, H.

2011-01-01

Highlights: → We measure shielding properties of dwelling houses in the central region of Syria. → The concrete used for ceiling construction is good for shielding from gamma radiations. → Fairly high linear attenuation coefficients are obtained (from 0.173 to 0.198 cm -1 ). → Blocks used for house walls are not effective against gamma radiations. → Blocks efficiency can be improved by filling their holes with a cement paste. - Abstract: The shielding properties of the concrete and blocks used for the construction of dwelling houses in the Central Region of Syria (CRS) were measured and studied. The concrete used for the ceiling construction was found to have optimum shielding properties with 0.182 cm -1 (or equivalently 0.0859 cm 2 g -1 ) for the linear (mass) attenuation coefficient [L(M)AC]. In addition gamma radiation is attenuated by 73.221% on average, while the blocks used for the walls have smaller LACs (0.082 cm -1 for the bare blocks, and 0.118 cm -1 for the coated ones). Although the LACs for the blocks are smaller than those for the concrete their shielding properties are good to protect from the gamma radiations coming from radioactive or nuclear accidents (78.630% attenuation), even Chernobyl - like disasters, because of their big width (10-12 cm). The LACs were measured by an ionization chamber and simple theoretical calculations have been made to predict the concrete LACs. The calculations showed an average LAC for the six samples equal to 0.1664 cm -1 with 8.47% error with respect to the experimental values. The average LAC for the concrete used for ceiling construction in the CRS was found to be comparable or even better than the average of some international values for the reactor shielding concretes, which are about 0.163 cm -1 .

Attenuation of Neutron and Gamma Radiation by a Composite Material Based on Modified Titanium Hydride with a Varied Boron Content

Science.gov (United States)

Yastrebinskii, R. N.

2018-04-01

The investigations on estimating the attenuation of capture gamma radiation by a composite neutron-shielding material based on modified titanium hydride and Portland cement with a varied amount of boron carbide are performed. The results of calculations demonstrate that an introduction of boron into this material enables significantly decreasing the thermal neutron flux density and hence the levels of capture gamma radiation. In particular, after introducing 1- 5 wt.% boron carbide into the material, the thermal neutron flux density on a 10 cm-thick layer is reduced by 11 to 176 factors, and the capture gamma dose rate - from 4 to 9 times, respectively. The difference in the degree of reduction in these functionals is attributed to the presence of capture gamma radiation in the epithermal region of the neutron spectrum.

Measurement of γ-Ray Attenuation Coefficient for Concrete with Different Aggregate

Energy Technology Data Exchange (ETDEWEB)

Oh, Jeong Hwan [Jeju National University, Jeju (Korea, Republic of); Lee, Jea Hyung; Mun, Young Bum; Choi, Hyun Kook [Sungshin Cement Co, Sejong (Korea, Republic of); Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of)

2016-05-15

In this work, we used different aggregates in a concrete to examine their effect on gamma-ray shielding. In addition, attenuation coefficient has been evaluated using a gamma-ray measuring system. The attenuation coefficient represents the amount of attenuated radiation by the thickness of a given sample material. Shielding performance improvement is expected to effect on the increasing high-weight aggregate rather than unit weigh and it is consider that additional research is needed for mixing condition of aggregates. In this study, shielding performance of concrete was confirmed to increase, according to the increasing in unit weight and aggregate. However, Iron ore is the density greater than oxidizing slag gravel, but attenuation coefficient is lower than including oxidizing slag gravel. The demand of radiation shielding material for a safe transport and storage of radioactive materials increases rapidly with the commencement of the medium and low-level radioactive waste disposal facility. It is because radioactive materials from a nuclear reactor, spent nuclear fuels, fission products, and many industrial application of radiation influences on environment over a long period by releasing gamma-ray and neutron continuously. Typical radiation shielding materials are lead, boron, iron, water, heavy-weight concrete, etc. In heavy-weight concrete, oxidizing slag from an electric arc furnace, magnetite and barite are used as an aggregate. The radiation shielding rate of the heavy-weight concrete which used oxidizing slag was studied. Both size of coarse aggregate and experiment sample is a few cm thicknesses. Therefore, location of shielding material including metal component in sample is important, according to direction of radiation.

Unfocused beam patterns in nonattenuating and attenuating fluids

International Nuclear Information System (INIS)

Goldstein, Albert

2004-01-01

The most important aspect of an ultrasound measuring system is knowledge of the transducer beam pattern. At all depths accurate single integral equations have been derived for the full beam pattern of steady state unfocused circular flat piston sources radiating into nonattenuating and attenuating fluids. The axial depth of the beginning of the unattenuated beam pattern far field is found to be at 6.41Y 0 . The unattenuated single integral equations are identical to a Jinc function directivity term at this and deeper depths. For attenuating fluids values of α and z are found that permit the attenuated axial pressure to be represented by a plane wave multiplicative exponential attenuation factor. This knowledge will aid in the experimental design of highly accurate attenuation measurements. Accurate single integral equations for the attenuated full beam pattern are derived using complex Bessel functions

The mechanical properties of radiation-vulcanized NR/BR blending system

Energy Technology Data Exchange (ETDEWEB)

Yan Aoshuang E-mail: yanas@public3.bta.net.cn; Guo Zhengtao; Li Li; Zhai Ying; Zhou Peng

2002-03-01

The effect of radiation dose on the mechanical properties of NR/BR blending system is reported in this paper. A comparison was made between sulphur vulcanization and radiation vulcanization for an optimal nature rubber (NR)/ butyl rubber (BR) blending ratio (60/40) at dose range from 10 to 150 kGy. The result shows that the mechanical properties, especially, tensile strength, elongation at break, and tear strength have been improved significantly by radiation-vulcanization. This finding was also proved by thermal aging experiment on a selected NR/BR blend at 70 deg. C for up to 168 h.

Attenuation of 60Co gamma rays by barium acrylic resin composite shields

International Nuclear Information System (INIS)

Abdulla, Riaz; Fidha, Mariyam; Sripathi Rao, B.H.; Kudkuli, Jagadish; Rekha, P.D.; Sharma, S.D.

2015-01-01

Oral squamous cell carcinoma is the sixth most common cancer reported globally, with an annual incidence of over 300,000 cases, of which 62% arise in developing countries. Radiation therapy is a treatment modality that uses ionizing radiation as a therapeutic agent. It is widely employed in the treatment of head and neck cancer, as a primary therapy coupled with surgical procedure and chemotherapy or as a palliative treatment for advanced tumors. However, radiotherapy can cause a series of complications such as xerostomia, mucositis, osteoradionecrosis, and radiation caries. Composite circular disc containing different ratios of acrylic and barium sulfate (BaSO 4 ) were made in-house. The purpose of this study was to evaluate the percentage attenuation from these composite shields in 60 Co gamma rays. A maximum of 8% radiation attenuation was achieved using 1:4 ratio of acrylic-BaSO 4 composite shields. The study proposes BaSO 4 as one of the compounds in combination with acrylic resin or any other thermoplastic substances for making biocompatible radiation attenuating devices. (author)

Evaluation of attenuating materials: model for the distribution of scattered radiation

International Nuclear Information System (INIS)

Costa, Paulo R.

1996-01-01

A mathematical model for the behaviour of the distribution of photon scattered by attenuating media is presented. Shielding barriers or attenuating materials used in tests of quality control in radiology are proposed. Comparative results for Lucite are reported

A preliminary assessment of the effects of radiation on polymer properties

International Nuclear Information System (INIS)

Dickson, L.W.

1988-01-01

The literature on the effects of radiation on the properties of various polymers and composites has been briefly reviewed for the purpose of identifying polymeric materials that could be irradiated to improve their performance. Radiation treatment of polymers may lead to cross-linking or chain scission reactions, depending on the chemical nature of the polymer. Cross-linking generally leads to an improvement in the mechanical properties of the polymer. Chain scission leads to deterioration in mechanical properties. The properties of irradiated polymers also depend on the degree of polymer crystallinity and the irradiation conditions, including dose rate and the presence of oxygen, cross-linking agents and other additives. A 30% increase in the tensile strength of many polymers may be obtained by radiation cross-linking under appropriate conditions. 40 refs

Immunity to schistosomiasis mansoni in guinea-pigs vaccinated with radiation-attenuated cercariae

International Nuclear Information System (INIS)

Gordon, J.R.; McLaren, D.J.

1987-01-01

The anti-schistosomular humoral responses of guinea-pigs vaccinated with radiation-attenuated cercariae of Schistosoma mansoni have been investigated in vitro. The sera of vaccinated animals contain schistosomulicidal complement-fixing antibodies which peak in titre at week 5 after vaccination and predominantly consist of IgG 2 and IgM antibodies. The ability of the serum to arm macrophages from normal animals to bind to schistosomula, also peaks in titre at week 5 and is associated with IgG 2 antibodies. Basophils from normal animals can be sensitized in vitro by vaccine serum to degranulate in the presence of schistosomular antigens. This anaphylactic antibody activity is associated with IgG 1 but not IgE antibodies, and peaks in titre at week 10. Three antigens (14 kD, 20 kD and 43 kD) are specifically and transiently detected by vaccine serum on Western blots of schistosomular proteins; these antigens are first discernible at week 4, but were virtually undetectable at week 12. (author)

Perturbed effects at radiation physics

International Nuclear Information System (INIS)

Külahcı, Fatih; Şen, Zekâi

2013-01-01

Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed

Study of radiation dose attenuation by skull bone in head during radiotherapy treatment using MCNP

Energy Technology Data Exchange (ETDEWEB)

Menezes, Artur F.; Boia, Leonardo S.; Trombetta, Debora M.; Martins, Maximiano C.; Reis Junior, Juraci P.; Silva, Ademir X., E-mail: ademir@con.ufrj.b [Coordenacao dos Programas de Pos-Graduacao de Engenharia (PEN/COPPE/UFRJ), RJ (Brazil). Programa de Engenharia Nuclear; Batista, Delano V.S., E-mail: delano@inca.gov.b [Instituto Nacional do Cancer (INCa), Rio de Janeiro, RJ (Brazil). Dept. de Fisica Medica

2011-07-01

In this study the MCNPX code was used to investigate possible influences of the attenuation beam by the surface bone during radiotherapy treatments of the skull. The computer simulation was performed on topographic image obtained from the National Cancer Institute, in Rio de Janeiro, database of patients treated with radiotherapy. The image segmentation process were performed using the SAPDI program developed to this purpose. The segmented image conversion for the input file recognized by MCNPX code was performed by SCAN2MCNP Software. The simulation was done using 10MeV Clinac 2300C spectrum considering two opposite parallel beams, with field size 2x2 and 4x4 cm{sup 2}, incident on a slice located above the eyes, containing two row of detectors positioned on the central region with a radius of 0.03 cm and arranged perpendicular to the radiation beams. After analyze the results, the relative error values in the range of 2 at 4% for the high dose region, and 26 at 37% for the low dose area were found, respectively. These differences were attributed to the radiation field attenuation on the bone surface at the entrance of the beam. It was observed that most situations on the high dose region the beam profile, from more realistic scenarios, became smaller than the one obtained when the tomography image was considered consisting of water. However for the low dose area the profile, obtained of the realistic situation, became higher than the one which was obtained when the tomography image was considered consisting of water. The results showed significant differences between both analyzed cases which show the need to use a correction factor by the treatment planning system used in radiotherapy services when the real chemical composition of patient head is unconsidered during the patient treatment planning. (author)

Study of radiation dose attenuation by skull bone in head during radiotherapy treatment using MCNP

International Nuclear Information System (INIS)

Menezes, Artur F.; Boia, Leonardo S.; Trombetta, Debora M.; Martins, Maximiano C.; Reis Junior, Juraci P.; Silva, Ademir X.; Batista, Delano V.S.

2011-01-01

In this study the MCNPX code was used to investigate possible influences of the attenuation beam by the surface bone during radiotherapy treatments of the skull. The computer simulation was performed on topographic image obtained from the National Cancer Institute, in Rio de Janeiro, database of patients treated with radiotherapy. The image segmentation process were performed using the SAPDI program developed to this purpose. The segmented image conversion for the input file recognized by MCNPX code was performed by SCAN2MCNP Software. The simulation was done using 10MeV Clinac 2300C spectrum considering two opposite parallel beams, with field size 2x2 and 4x4 cm 2 , incident on a slice located above the eyes, containing two row of detectors positioned on the central region with a radius of 0.03 cm and arranged perpendicular to the radiation beams. After analyze the results, the relative error values in the range of 2 at 4% for the high dose region, and 26 at 37% for the low dose area were found, respectively. These differences were attributed to the radiation field attenuation on the bone surface at the entrance of the beam. It was observed that most situations on the high dose region the beam profile, from more realistic scenarios, became smaller than the one obtained when the tomography image was considered consisting of water. However for the low dose area the profile, obtained of the realistic situation, became higher than the one which was obtained when the tomography image was considered consisting of water. The results showed significant differences between both analyzed cases which show the need to use a correction factor by the treatment planning system used in radiotherapy services when the real chemical composition of patient head is unconsidered during the patient treatment planning. (author)

Mechanical Loading Attenuates Radiation-Induced Bone Loss in Bone Marrow Transplanted Mice

Science.gov (United States)

Govey, Peter M.; Zhang, Yue; Donahue, Henry J.

2016-01-01

Exposure of bone to ionizing radiation, as occurs during radiotherapy for some localized malignancies and blood or bone marrow cancers, as well as during space travel, incites dose-dependent bone morbidity and increased fracture risk. Rapid trabecular and endosteal bone loss reflects acutely increased osteoclastic resorption as well as decreased bone formation due to depletion of osteoprogenitors. Because of this dysregulation of bone turnover, bone’s capacity to respond to a mechanical loading stimulus in the aftermath of irradiation is unknown. We employed a mouse model of total body irradiation and bone marrow transplantation simulating treatment of hematologic cancers, hypothesizing that compression loading would attenuate bone loss. Furthermore, we hypothesized that loading would upregulate donor cell presence in loaded tibias due to increased engraftment and proliferation. We lethally irradiated 16 female C57Bl/6J mice at age 16 wks with 10.75 Gy, then IV-injected 20 million GFP(+) total bone marrow cells. That same day, we initiated 3 wks compression loading (1200 cycles 5x/wk, 10 N) in the right tibia of 10 of these mice while 6 mice were irradiated, non-mechanically-loaded controls. As anticipated, before-and-after microCT scans demonstrated loss of trabecular bone (-48.2% Tb.BV/TV) and cortical thickness (-8.3%) at 3 wks following irradiation. However, loaded bones lost 31% less Tb.BV/TV and 8% less cortical thickness (both pbones also had significant increases in trabecular thickness and tissue mineral densities from baseline. Mechanical loading did not affect donor cell engraftment. Importantly, these results demonstrate that both cortical and trabecular bone exposed to high-dose therapeutic radiation remain capable of an anabolic response to mechanical loading. These findings inform our management of bone health in cases of radiation exposure. PMID:27936104

Infrared radiation properties of anodized aluminum

Energy Technology Data Exchange (ETDEWEB)

Kohara, S. [Science Univ. of Tokyo, Noda, Chiba (Japan). Dept. of Materials Science and Technology; Niimi, Y. [Science Univ. of Tokyo, Noda, Chiba (Japan). Dept. of Materials Science and Technology

1996-12-31

The infrared radiation heating is an efficient and energy saving heating method. Ceramics have been used as an infrared radiant material, because the emissivity of metals is lower than that of ceramics. However, anodized aluminum could be used as the infrared radiant material since an aluminum oxide film is formed on the surface. In the present study, the infrared radiation properties of anodized aluminum have been investigated by determining the spectral emissivity curve. The spectral emissivity curve of anodized aluminum changed with the anodizing time. The spectral emissivity curve shifted to the higher level after anodizing for 10 min, but little changed afterwards. The infrared radiant material with high level spectral emissivity curve can be achieved by making an oxide film thicker than about 15 {mu}m on the surface of aluminum. Thus, anodized aluminum is applicable for the infrared radiation heating. (orig.)

Degrading radiation effects on properties of bromobutyl rubber compounds

Energy Technology Data Exchange (ETDEWEB)

Scagliusi, Sandra R.; Cardoso, Elisabeth C.L.; Pozenato, Cristina A.; Lugao, Ademar B., E-mail: srscagliusi@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2013-07-01

The understanding of chemistry involved in degradation induced radiation is becoming more and more relevant in the re-use of polymeric materials, as well in beneficial radiation uses. Degrading radiation effects have been considered from viewpoint of controlled degradation for isoprene/isobutene in rubbers for recycling purposes. Bromobutyl rubber (BIIR) is an isobutylene/isoprene copolymer comprising 1.9 to 2.1% bromine and has a lot of applications including in tires air-chambers. In this work there were evaluated gamma-irradiation effects for re-use or recycling objectives in elastomeric bromobutyl compositions irradiated at 5, 15, 25, 50, 100,150 and 200 kGy. Mechanical properties, hardness and swelling were assessed in non-vulcanized and vulcanized rubber, non-irradiated and irradiated at different doses. The major gamma radiation effect in butyl rubber is the generation of free radicals along changes in mechanical properties. Irradiation effects in bromobutyl rubber compounds were comprehensively investigated, demonstrated and discussed. (author)

Degrading radiation effects on properties of bromobutyl rubber compounds

International Nuclear Information System (INIS)

Scagliusi, Sandra R.; Cardoso, Elisabeth C.L.; Pozenato, Cristina A.; Lugao, Ademar B.

2013-01-01

The understanding of chemistry involved in degradation induced radiation is becoming more and more relevant in the re-use of polymeric materials, as well in beneficial radiation uses. Degrading radiation effects have been considered from viewpoint of controlled degradation for isoprene/isobutene in rubbers for recycling purposes. Bromobutyl rubber (BIIR) is an isobutylene/isoprene copolymer comprising 1.9 to 2.1% bromine and has a lot of applications including in tires air-chambers. In this work there were evaluated gamma-irradiation effects for re-use or recycling objectives in elastomeric bromobutyl compositions irradiated at 5, 15, 25, 50, 100,150 and 200 kGy. Mechanical properties, hardness and swelling were assessed in non-vulcanized and vulcanized rubber, non-irradiated and irradiated at different doses. The major gamma radiation effect in butyl rubber is the generation of free radicals along changes in mechanical properties. Irradiation effects in bromobutyl rubber compounds were comprehensively investigated, demonstrated and discussed. (author)

Radiation effect on polyethylene tube operational properties

International Nuclear Information System (INIS)

Kagan, D.F.; Kantor, L.A.; Sokolov, I.A.; Pogrebetskij, G.E.; Perlova, N.A.; Chumakov, V.V.

1975-01-01

The operational properties (stability on prolonged usage and creeping) were determined for pressure pipes made of high-density and low-density polyethylene subjected to γ-radiation. The dependence of the period up to the breaking point on the radiation dosage was extreme in character, with a maximum being near 25 Mrad. With an increase in the irradiation dosage the character of the breaking changes from plastic (at 0-15 Mrad) to brittle (at higher dosages). The plots of creepage, indepent from the amount of radiation, can be described by logarithmic equation epsilon=epsilonsub(0)+K lgt (where, epsilon-deformation of creepage, %; epsilonsub(0)- and K - creepage constants). Therefore creepage can be considered as a criterion determining the carrying capacity of the γ-irradiated polyethylene. It was established that only radiation-grafted high-density polyethylene is suitable for hot water supply pipes

Tailoring Thermal Radiative Properties with Doped-Silicon Nanowires

Energy Technology Data Exchange (ETDEWEB)

Zhang, Zhuomin [Georgia Inst. of Technology, Atlanta, GA (United States)

2017-08-28

Aligned doped-silicon nanowire (D-SiNW) arrays form a hyperbolic metamaterial in the mid-infrared and have unique thermal radiative properties, such as broadband omnidirectional absorption, low-loss negative refraction, etc. A combined theoretical and experimental investigation will be performed to characterize D-SiNW arrays and other metamaterials for tailoring thermal radiative properties. Near-field thermal radiation between anisotropic materials with hyperbolic dispersions will also be predicted for potential application in energy harvesting. A new kind of anisotropic metamaterial with a hyperbolic dispersion in a broad infrared region has been proposed and demonstrated based on aligned doped-silicon nanowire (D-SiNW) arrays. D-SiNW-based metamaterials have unique thermal radiative properties, such as broadband omnidirectional absorption whose width and location can be tuned by varying the filling ratio and/or doping level. Furthermore, high figure of merit (FOM) can be achieved in a wide spectral region, suggesting that D-SiNW arrays may be used as a negative refraction material with much less loss than other structured materials, such as layered semiconductor materials. We have also shown that D-SiNWs and other nanostructures can significantly enhance near-field thermal radiation. The study of near-field radiative heat transfer between closely spaced objects and the electromagnetic wave interactions with micro/nanostructured materials has become an emerging multidisciplinary field due to its importance in advanced energy systems, manufacturing, local thermal management, and high spatial resolution thermal sensing and mapping. We have performed extensive study on the energy streamlines involving anisotropic metamaterials and the applicability of the effective medium theory for near-field thermal radiation. Graphene as a 2D material has attracted great attention in nanoelectronics, plasmonics, and energy harvesting. We have shown that graphene can be used to

Higher plant acclimation to solar ultraviolet-B radiation

International Nuclear Information System (INIS)

Robberecht, R.

1981-01-01

The objectives of this study were to determine: (1) the relationship between plant sensitivity and epidermal uv attenuation, (2) the effect of phenotypic changes in the leaf epidermis, resulting from uv-B exposure, on plant sensitivity to uv radiation, and (3) the platicity of these changes in the epidermis leading to plant acclimation to uv-B radiation. A mechanism of uv-B attenuation, possibly involving the biosynthesis of uv-absorbing flavonoid compounds in the epidermis and mesophyll under the stress of uv-B radiation, and a subsequent increase in the uv-B attenuation capacity of the epidermis, is suggested. The degree of plant sensitivity and acclimation to natural and intensified solar uv-B radiation may involve a dynamic balance between the capacity for uv-B attenuation and uv-radiation-repair mechanisms in the leaf

Evaluation of downwelling diffuse attenuation coefficient algorithms in the Red Sea

KAUST Repository

Tiwari, Surya Prakash; Yellepeddi, Sarma B.; Jones, Burton

2016-01-01

to comprehend the diffuse attenuation coefficient and its relationship with in situ properties. Two apparent optical properties, spectral remote sensing reflectance (Rrs) and the downwelling diffuse attenuation coefficient (Kd), are calculated from vertical

Evaluation of X ray attenuation by means of radiographic images

International Nuclear Information System (INIS)

Barros, Frieda Saicla; Paredes, Ramon S.C.; Godoi, Walmor C.; Souza, Gabriel Pinto de

2011-01-01

This paper's main goal is to adopt a qualitative methodology to evaluate the attenuation of x-radiation through X-ray images in polymeric materials plus residual lead. To determinate the images it was initially used an experimental setup at the Laboratory for Materials Diagnostics LACTEC. These results correspond to a more qualitative analysis, even with quantitative answers. Through analysis of radiographic images we can measure the intensity of radiation that goes through the plate, making possible to establish a relationship between the attenuation coefficient and the thickness of the material. (author)

Pulsed x-ray induced attenuation measurements of single mode optical fibers and coupler materials

International Nuclear Information System (INIS)

Johan, A.; Charre, P.

1994-01-01

Pulsed X-ray induced transient radiation attenuation measurements of single mode optical fibers have been performed versus total dose, light wavelength, optical power and fiber coil diameter in order to determine the behavior of parameters sensitive to ionizing radiation. The results did not show any photobleaching phenomenon and the attenuation was found independent of the spool diameter. As expected, transient attenuation was lower for higher wave-lengths. The recovery took place in the millisecond range and was independent of total dose, light wavelength and optical power. In optical modules and devices a large range of behaviors was observed according to coupler material i.e., Corning coupler showed a small peak attenuation that remained more than one day later; on the other hand LiTaO 3 material experienced an order of magnitude higher peak attenuation and a recovery in the millisecond range. For applications with optical fibers and integrated optics devices the authors showed that in many cases the optical fiber (length above 100 m) is the most sensitive device in a transient ionizing radiation field

On the radiative and thermodynamic properties of the cosmic radiations using COBE FIRAS instrument data: I. Cosmic microwave background radiation

Science.gov (United States)

Fisenko, Anatoliy I.; Lemberg, Vladimir

2014-07-01

Using the explicit form of the functions to describe the monopole and dipole spectra of the Cosmic Microwave Background (CMB) radiation, the exact expressions for the temperature dependences of the radiative and thermodynamic functions, such as the total radiation power per unit area, total energy density, number density of photons, Helmholtz free energy density, entropy density, heat capacity at constant volume, and pressure in the finite range of frequencies v 1≤ v≤ v 2 are obtained. Since the dependence of temperature upon the redshift z is known, the obtained expressions can be simply presented in z representation. Utilizing experimental data for the monopole and dipole spectra measured by the COBE FIRAS instrument in the 60-600 GHz frequency interval at the temperature T=2.72548 K, the values of the radiative and thermodynamic functions, as well as the radiation density constant a and the Stefan-Boltzmann constant σ are calculated. In the case of the dipole spectrum, the constants a and σ, and the radiative and thermodynamic properties of the CMB radiation are obtained using the mean amplitude T amp=3.358 mK. It is shown that the Doppler shift leads to a renormalization of the radiation density constant a, the Stefan-Boltzmann constant σ, and the corresponding constants for the thermodynamic functions. The expressions for new astrophysical parameters, such as the entropy density/Boltzmann constant, and number density of CMB photons are obtained. The radiative and thermodynamic properties of the Cosmic Microwave Background radiation for the monopole and dipole spectra at redshift z≈1089 are calculated.

Omega-3 Polyunsaturated Fatty Acids Attenuate Radiation-induced Oxidative Stress and Organ Dysfunctions in Rats

International Nuclear Information System (INIS)

Abdel Aziz, N.; Yacoub, S.F.

2013-01-01

The Aim of the present study was to determine the possible protective effect of omega-3 polyunsaturated fatty acids (omega-3 PUFA) against radiation-induced oxidative stress associated with organ dysfunctions. Omega-3 PUFA was administered by oral gavages to male albino rats at a dose of 0.4 g/ kg body wt daily for 4 weeks before whole body γ-irradiation with 4Gy. Significant increase of serum lipid peroxidation end product as malondialdehyde (MDA) along with the reduction in blood glutathione (GSH) content, superoxide dismutase (SOD) and glutathione peroxidase (GPX) enzyme activities were recorded on 3rd and 8th days post-irradiation. Oxidative stress was associated with a significant increase in lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) enzyme activities, markers of heart damage, significant increases in uric acid, urea and creatinine levels, markers of kidney damage, significant increases of alkaline phosphatase (ALP) and transaminases (ALT and AST) activities, markers of liver damage. Moreover significant increases in total cholesterol and triglycerides levels were recorded. Omega-3 PUFA administration pre-irradiation significantly attenuated the radiation-induced oxidative stress and organ dysfunctions tested in this study. It could be concluded that oral supplementation of omega-3 PUFA before irradiation may afford protection against radiation-induced oxidative stress and might preserve the integrity of tissue functions of the organs under investigations.

Foundations of radiation physics and radiation protection. 5. ed.

International Nuclear Information System (INIS)

Krieger, Hanno

2017-01-01

The following topics are dealt with: Types of radiation and radiation fields, the atomic structure, radioactive decays, decay law, natural and artificial radioactivity, interactions of ionizing photon radiation, attenuation of neutral-particle beams, interactions of neutron radiation, interactions of charged particles, ionization and energy transfer, radiation doses, radiation protection phantoms, foundations of the radiation biology of cells, effects and risks of ionizing radiation, radiation expositions of men with ionizing radiation, radiation protection law, practical radiation protection against ionizing radiations, radiation eposures in medical radiology. (HSI)

Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate.

Science.gov (United States)

Warren, L M; Mackenzie, A; Dance, D R; Young, K C

2013-04-07

Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

Integration of optical fibers in radiative environments: Advantages and limitations

International Nuclear Information System (INIS)

Girard, S.; Ouerdane, Y.; Boukenter, A.; Marcandella, C.; Bisutti, J.; Baggio, J.; Meunier, J. P.

2011-01-01

We review the advantages and limitations for the integration of optical fibers in radiative environments. Optical fibers present numerous advantages for applications in harsh environments such as their electromagnetic immunity. This explains the increasing interest of the radiation effects community to evaluate their vulnerability for future facilities. However, it is also well-known that optical fibers suffer from a degradation of their macroscopic properties under irradiation. We illustrate the major mechanisms and parameters that govern the degradation mechanism, mainly the radiation-induced attenuation phenomena. We focus on the fiber transient radiation responses when exposed to the pulsed and mixed environment associated with the Megajoule class lasers devoted to the fusion by inertial confinement study. (authors)

Radiative properties of optical board embedded with optical black holes

International Nuclear Information System (INIS)

Qiu, J.; Liu, L.H.; Hsu, P.-F.

2011-01-01

Unique radiative properties, such as wavelength-selective transmission or absorption, have been intensively studied. Historically, geometries for wavelength-selective of light absorption were developed based on metallic periodical structures, which were only applied in the case of TM wave incidence due to the excitation of surface plasmons. In this paper, we develop an alternative approach to selective wavelength of light absorption (both TE and TM waves), based on an optical board periodical embedded with optical black holes. Numerical work was carried out to study such structure's radiative properties within the wavelength range of 1-100 μm. The electromagnetic wave transmission through such a structure is predicted by solving Maxwell's equations using the finite-difference time-domain (FDTD) method. Spectral absorptance varies with the period of optical black holes. When the incidence wavelength is much larger than the inner core radius, most of the light energy will be transmitted through the inner core. Otherwise, the energy will be mainly absorbed. Numerical results of the radiative properties of the optical board with different incidence wavelengths are also obtained. The effect of the oblique incidence wave is investigated. This study helps us gain a better understanding of the radiative properties of an optical board embedded with optical black holes and develop an alternative approach to selective light absorption.

Radiation processing and functional properties of soybean (Glycine max)

International Nuclear Information System (INIS)

Pednekar, Mrinal; Das, Amit K.; Rajalakshmi, V; Sharma, Arun

2010-01-01

Effect of radiation processing (10, 20 and 30 kGy) on soybean for better utilization was studied. Radiation processing reduced the cooking time of soybean and increased the oil absorption capacity of soy flour without affecting its proximate composition. Irradiation improved the functional properties like solubility, emulsification activity and foam stability of soybean protein isolate. The value addition effect of radiation processing has been discussed for the products (soy milk, tofu and tofu fortified patties) prepared from soybean.

Development of a human live attenuated West Nile infectious DNA vaccine: Suitability of attenuating mutations found in SA14-14-2 for WN vaccine design

Energy Technology Data Exchange (ETDEWEB)

Yamshchikov, Vladimir, E-mail: yaximik@gmail.com; Manuvakhova, Marina; Rodriguez, Efrain

2016-01-15

Direct attenuation of West Nile (WN) virus strain NY99 for the purpose of vaccine development is not feasible due to its high virulence and pathogenicity. Instead, we created highly attenuated chimeric virus W1806 with the serological identity of NY99. To further attenuate W1806, we investigated effects of mutations found in Japanese encephalitis virus vaccine SA14-14-2. WN viruses carrying all attenuating mutations lost infectivity in mammalian, but not in mosquito cells. No single reversion restored infectivity in mammalian cells, although increased infectivity in mosquito cells was observed. To identify a subset of mutations suitable for further attenuation of W1806, we analyzed effects of E{sub 138}K and K{sub 279}M changes on virulence, growth properties, and immunogenicity of derivatized W956, from which chimeric W1806 inherited its biological properties and attenuation profile. Despite strong dominant attenuating effect, introduction of only two mutations was not sufficient for attenuating W1806 to the safety level acceptable for human use. - Highlights: • Further attenuation of a WN vaccine precursor is outlined. • Effect of SA14-14-2 attenuating mutations is tested. • Mechanism of attenuation is proposed and illustrated. • The need for additional attenuating mutations is justified.

Physicomechanical properties of PVC radiation-modified by tridecaethyleneglycol methacrylic ester

International Nuclear Information System (INIS)

Lomonosova, N.V.

1988-01-01

A study was made on physicomechanical properties of radiation-modified system on the basis of PVC and TGM-13 oligomer (dimethacrylic ester of tridecaethyleneglycol, 43.2%). Main physical properties of the composition (maximal stresses, softening point, double refraction value, activation energy, temperature positions of the first and the second maximums on isometric heating diagram) were used to determine its isotropic and oriented states, depending on absorbed radiation dose (0-128 kGy). It is shown that radiation PVC modification by TGM-13 oligomer results in formation of linked 'soft' plastic. In terms of strength it is on a par with isotropic linear PVC, but compare favourably with it with respect to t ρ and ε

The Atmospheric Radiation Measurement Program May 2003 Intensive Operations Period Examining Aerosol Properties and Radiative Influences: Preface to Special Section

Science.gov (United States)

Ferrare, Richard; Feingold, Graham; Ghan, Steven; Ogren, John; Schmid, Beat; Schwartz, Stephen E.; Sheridan, Pat

2006-01-01

Atmospheric aerosols influence climate by scattering and absorbing radiation in clear air (direct effects) and by serving as cloud condensation nuclei, modifying the microphysical properties of clouds, influencing radiation and precipitation development (indirect effects). Much of present uncertainty in forcing of climate change is due to uncertainty in the relations between aerosol microphysical and optical properties and their radiative influences (direct effects) and between microphysical properties and their ability to serve as cloud condensation nuclei at given supersaturations (indirect effects). This paper introduces a special section that reports on a field campaign conducted at the Department of Energy Atmospheric Radiation Measurement site in North Central Oklahoma in May, 2003, examining these relations using in situ airborne measurements and surface-, airborne-, and space-based remote sensing.

Lithium-doped hydroxyapatite nano-composites: Synthesis, characterization, gamma attenuation coefficient and dielectric properties

Science.gov (United States)

Badran, H.; Yahia, I. S.; Hamdy, Mohamed S.; Awwad, N. S.

2017-01-01

Lithium-hydroxyapatite (0, 1, 5, 10, 20, 30 and 40 wt% Li-HAp) nano-composites were synthesized by sol-gel technique followed by microwave-hydrothermal treatment. The composites were characterized by X-ray diffraction (XRD), Field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and Raman techniques. Gamma attenuation coefficient and the dielectric properties for all composites were investigated. The crystallinity degree of Li-doped HAp was higher than that of un-doped HAp. Gamma attenuation coefficient values increased from 0.562 cm-1 for 0 wt% Li-HAp to 2.190 cm-1 for 40 wt% Li-HAp. The alternating current conductivity increased with increasing frequency. The concentration of Li affect the values of dielectric constant where Li doped HAp of low dielectric constant can have an advantage for healing in bone fractures. The calcium to phosphorus ratio decreased from 1.43 to 1.37 with the addition of lithium indicating the Ca deficiency in the studied composites. Our findings lead to the conclusion that Li-HAp is a new nano-composite useful for medical applications and could be doped with gamma shield materials.

GSK-3β Inhibition Attenuates LPS-Induced Death but Aggravates Radiation-Induced Death via Down-Regulation of IL-6

Directory of Open Access Journals (Sweden)

Bailong Li

2013-12-01

Full Text Available Background: Exposure of high dose ionizing radiation is lethal. Signal pathways involved in radiation biology reaction still remain illdefined. Lipopolysaccharides (LPS, the ligands of Toll-like receptor 4(TLR4, could elicit strong immune responses. Glycogen synthase kinase-3β(GSK-3β promotes the production of inflammatory molecules and cell migration. Inhibition of GSK-3β provides protection against inflammation in animal models. The aim of the study was to investigate role of GSK-3β in LPS shock and ionizing radiation. Methods: WT or IL-6-/-mice or cells were pretreated with SB216763, a GSK-3β inhibitor, and survival of the mice was determined. Cell viability was assayed by Cell Counting Kit. Apoptosis was assayed by Annexin V-PI double staining. Serum concentrations of IL-6 and TNF-α were determined by ELISA. Results: SB216763 attenuated LPS induced mice or cell death but aggravated radiation induced mice or cell death. SB216763 reduced IL-6, but not TNF-α levels in vivo. IL-6-/- mice were more resistant to LPS-induced death but less resistant to radiation-induced death than wild type mice. Conclusions: Inhibition of GSK-3β conferred resistance to LPS shock but fostered death induced by ionizing radiation. Inhibition of GSK-3β was effective by reducing IL-6.

Properties of solar generators with reflectors and radiators

Science.gov (United States)

Ebeling, W. D.; Rex, D.; Bierfischer, U.

1980-06-01

Radiation cooled concentrator systems using silicon and GaAs cells were studied. The principle of radiation cooling by the reflector surfaces is discussed for cylindrical parabolic reflectors (SARA), truncated hexagonal pyramids, and a small trough configuration. Beam paths, collection properties for imperfect orientation, and thermal optimization parameters were analyzed. The three concentrating systems with radiation cooling offer advantages over the plane panel and over the large trough. With silicon solar cells they exhibit considerably lower solar cell consumption per Kw and also lower mass per kW. With GaAs cells the SARA system reduces the number of solar cells needed per kW to less than 10%. Also in all other cases SARA offers the best values for alpha and F sub sol, as long as narrow angular tolerances of the panel orientation can be met. Analysis of the energy collecting properties for imperfect orientation shows the superiority of the hexagonal concentrator. This device can produce power for even large angles between the sun and the panel normal.

Impact of morphology on the radiative properties of fractal soot aggregates

International Nuclear Information System (INIS)

Doner, Nimeti; Liu, Fengshan

2017-01-01

The impact of morphology on the radiative properties of fractal soot aggregates was investigated using the discrete dipole approximation (DDA). The optical properties of four different types of aggregates of freshly emitted soot with a fractal dimension D f =1.65 and a fractal pre-factor k f =1.76 were calculated. The four types of aggregates investigated are formed by uniform primary particles in point-touch, by uniform but overlapping primary particles, by uniform but enlarged primary particles in point-touch, and formed by point-touch and polydisperse primary particles. The radiative properties of aggregates consisting of N=20, 56 and 103 primary particles were numerically evaluated for a given refractive index at 0.532 and 1.064 μm. The radiative properties of soot aggregates vary strongly with the volume equivalent radius a eff and wavelength. The accuracy of DDA was evaluated in the first and fourth cases against the generalized multi-sphere Mie (GMM) solution in terms of the vertical–vertical differential scattering cross section (C vv ). The model predicted the average relative deviations from the base case to be within 15–25% for C vv , depending on the number of particles for the aggregate. The scattering cross sections are only slightly affected by the overlapping but more significantly influenced by primary particle polydispersity. It was also found that the enlargement of primary particles by 20% has a strong effect on soot aggregate radiative properties. - Highlights: • The radiative properties of aggregates of N=20, 56 and 103 primary particles were investigated. • Four different cases, formed by point-touch, overlapping, aggregate expansion and polydispersion, were studied. • The effects of overlapping and aggregate expansion on morphology are found to be the same.

Self-attenuation factors in gamma-ray spectrometry

International Nuclear Information System (INIS)

Korun, M.

1999-01-01

The relation between the self-attenuation factors and the distribution function describing the number of photons detected in the full-energy peaks, as a function of their path length in the sample is presented. The relations between the self-attenuation factor and the moments of the distribution function, the average path length and the variance are also presented. The use of these relations is illustrated by applying them to self-attenuation factors describing attenuation in cylindrical samples. The results of the calculations are compared with the measured average path lengths and discussed in terms of the properties of the distribution function. (author)

Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes

Science.gov (United States)

Basyigit, Celalettin; Uysal, Volkan; Kilinçarslan, Şemsettin; Mavi, Betül; Günoǧlu, Kadir; Akkurt, Iskender; Akkaş, Ayşe

2011-12-01

The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.

Investigating Radiation Shielding Properties of Different Mineral Origin Heavyweight Concretes

International Nuclear Information System (INIS)

Basyigit, Celalettin; Uysal, Volkan; Kilincarslan, Semsettin; Akkas, Ayse; Mavi, Betuel; Guenoglu, Kadir; Akkurt, Iskender

2011-01-01

The radiation although has hazardous effects for human health, developing technologies bring lots of usage fields to radiation like in medicine and nuclear power station buildings. In this case protecting from undesirable radiation is a necessity for human health. Heavyweight concrete is one of the most important materials used in where radiation should be shielded, like those areas. In this study, used heavyweight aggregates of different mineral origin (Limonite, Siderite), in order to prepare different series in concrete mixtures and investigated radiation shielding properties. The experimental results on measuring the radiation shielding, the heavyweight concrete prepared with heavyweight aggregates of different mineral origin show that, are useful radiation absorbents when they used in concrete mixtures.

Analysis and comparison of immune reactivity in guinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariae of Schistosoma mansoni

International Nuclear Information System (INIS)

Rogers, M.V.; McLaren, D.J.

1987-01-01

Guinea-pigs immunized with equivalent numbers of normal or radiation-attenuated cercariae of Schistosoma mansoni develop close to complete resistance to reinfection at weeks 12 and 4.5 respectively. We here analyse and compare the immune responses induced by the two populations of cercariae. Both radiation-attenuated and normal parasites of S. mansoni elicited an extensive germinal centre response in guinea-pigs by week 4.5 post-immunization. The anti-parasite antibody titre and cytotoxic activity of serum from 4.5-week-vaccinated, or 4.5-week-infected guinea-pigs were approximately equal, but sera from 12-week-infected individuals had high titres of anti-parasite antibody, which promoted significant larvicidal activity in vitro. In all cases, larvicidal activity was mediated by the IgG 2 fraction of the immune serum. Lymphocyte transformation tests conducted on splenic lymphocytes from 4.5-week vaccinated guinea-pigs revealed maximal stimulation against cercarial, 2-week and 3-week worm antigens, whereas spleen cells from 4.5-week-infected guinea-pigs were maximally stimulated by cercarial and 6-week worm antigens. The splenic lymphocyte responses of 12-week infected animals were dramatic against antigens prepared from all life-stages of the parasite. (author)

Gamma radiation effects on the rheological properties of high and low density polyethylenes

International Nuclear Information System (INIS)

Rangel-Nafaile, C.; Garcia-Rejon, A.; Garcia Leon, A.

1986-01-01

High energy radiation of polymeric materials is a topic of considerable interest from commercial and scientific points of view. Within an inert atmosphere, irradiation of polyethylene yields a crosslinking effect with a consequent improvement in its mechanical properties in comparison to the virgin materials. Additionally, if irradiated specimens are melted and recrystallized, the radiation-induced crosslinking hinders their crystalline growth altering dramatically their flow properties such as the elasticity. This work portrays the effects of the gamma radiation on the rheological properties of high and low density polyethylenes manufactured by PEMEX and analyzes the implications of theoretical results derived from the Acierno's model when it is implemented with the rheological properties of high energy irradiated polyethylenes. (author)

Comparative study of silicate glasses containing Bi2O3, PbO and BaO: Radiation shielding and optical properties

International Nuclear Information System (INIS)

Kirdsiri, K.; Kaewkhao, J.; Chanthima, N.; Limsuwan, P.

2011-01-01

Research highlights: → We change Bi 2 O 3 , PbO and BaO concentration in silicate glasses. → The densities of Bi 2 O 3 glasses more than PbO glasses and BaO glasses. → The Um of Bi 2 O 3 glasses and PbO glasses are comparable and more than BaO glasses. → This suggests that Bi 2 O 3 can replace PbO in radiation shielding glasses. - Abstract: The radiation shielding and optical properties of xBi 2 O 3 :(100-x)SiO 2 , xPbO:(100-x)SiO 2 and xBaO:(100-x)SiO 2 glass systems (where 30 ≤ x ≤ 70 is the composition by weight%) have been investigated. Total mass attenuation coefficients (μ m ) of glasses at 662 keV were improved by increasing their Bi 2 O 3 and PbO content, which raised the photoelectric absorption in glass matrices. Raising the BaO content to the same fraction range, however, brought no significant change to μ m . These results indicate that photon is strongly attenuated in Bi 2 O 3 and PbO containing glasses, and but not in BaO containing glass. The results from the optical absorption spectra show an edge that was not sharply defined; clearly indicating the amorphous nature of glass samples. It is observed that the cutoff wavelength for Bi 2 O 3 containing glass was longer than PbO and BaO containing glasses.

Radiation cured polyester compositions containing metal-properties

Science.gov (United States)

Szalińska, H.; Pietrzak, M.; Gonerski, A.

The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them.

Radiation cured polyester compositions containing metal-properties

International Nuclear Information System (INIS)

Szalinska, H.; Pietrzak, M.; Gonerski, A.

1987-01-01

The subject of the studies was unsaturated polyester resin, Polimal-109 and its compositions containing acrylates of: sodium, potassium, calcium, magnesium, barium, manganese, iron, cobalt, copper and acrylic acid. Polyester resin modified with acrylic acid salts was cured with 60 Co gamma radiation. Measurements of Vicat softening temperature, water absorption, creep current resistance, volume and surface resistivity, the tangent of dielectric loss angle and permittivity of radiation cured compositions were carried out. The results of the studies presented testify to the fact that the properties of cross-linked polymers alter after ionogenic compounds have been introduced into them. (author)

Physics of radiation

International Nuclear Information System (INIS)

Abd Nasir Ibrahim; Azali Muhammad; Ab Razak Hamzah; Abd Aziz Mohamed; Mohammad Pauzi Ismail

2004-01-01

This chapter discusses the following topics: concept of atom and elements; molecules and compounds; basic principles of radiation; types of radiations; radioactivity, unit of radioactivity, specific activity, radioactive decay, ionisation and ions, interaction of radiation with matters, modes of interaction: photoelectric absorption: Compton scattering, pair-production; attenuation of x and gamma radiation; build-up factors

Mechanical properties of polyamide 6,6/low density polyethylene blend by ionizing radiation

International Nuclear Information System (INIS)

Pino, Eddy S.; Feitosa, Marcos A.F.

2007-01-01

Polymer blending is a growing scientific and commercial development activity. In most of the cases, polymeric blends are formed by thermodynamically immiscible components. Such blends require the use of compatibilizers that, often, are copolymers, graft copolymers or any mean that improves the dispersion and adhesion of the blend phases. Compatibility of a polymer blend plays an important role in determining the blend properties for its end use. In this work, the improvement of mechanical properties of PA 6,6/LDPE 75/25% wt/wt composition blend, using electron radiation, was studied. Samples for mechanical test were melt-mixed in an extruder and then injection-molded. These samples were electron irradiated to overall doses of 50, 100, 150, 200 and 250 kGy. Tensile measurements have shown that the strength at break increases with an increase of radiation dose. Hardness Shore D measurements show that this property also increases as a function of radiation dose. On the other hand, Impact Izod tests show that the resistance to impact decreases with the increase of radiation dose. The behavior of these bulk and surface properties implies that ionizing radiation produces changes in the mechanical performance of the irradiated blend due to a combined radiation inducing effects, cross-linking and the compatibility of blend components. (author)

Gamma radiation effect study in polycarbonate optical and mechanics properties

International Nuclear Information System (INIS)

Araujo, E.S. de.

1991-02-01

Polycarbonates (PC) are used in different industrial applications due to their excellent dielectric characteristics, impact resistance, and high temperature resistance. In some of these applications, the polycarbonates are exposed to gamma radiation which produces molecular scissions, causing changes in the polycarbonate properties. To estimate the radiation effects in the Durolon polycarbonate, samples were irradiated with 60 Co gamma rays with doses between 0,2 kGy and 300 kGy. The results obtained showed that the PC mechanical properties are not changed due to the gamma radiation. However the results showed an expressive variation in the yellowness index for doses above 1 kGy. The results showed that it is possible to use the gamma sterilization of PC in applications where the coloration of PC is not critical. (author). 21 refs, 25 figs, 3 tabs

The ultraviolet attenuation law in backlit spiral galaxies

International Nuclear Information System (INIS)

Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

2014-01-01

The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

The ultraviolet attenuation law in backlit spiral galaxies

Energy Technology Data Exchange (ETDEWEB)

Keel, William C. [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487 (United States); Manning, Anna M. [Stennis Space Center, MS 39522 (United States); Holwerda, Benne W. [ESA-ESTEC, Keplerlaan 1, 2201-AZ Noordwijk (Netherlands); Lintott, Chris J. [Astrophysics, Oxford University, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Schawinski, Kevin, E-mail: wkeel@ua.edu, E-mail: ammanning@bama.ua.edu, E-mail: bholwerd@rssd.esa.int, E-mail: Twitter@BenneHolwerda, E-mail: cjl@astro.ox.ac.uk, E-mail: Twitter@chrislintott, E-mail: kevin.schawinski@phys.ethz.ch, E-mail: Twitter@kevinschawinski [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland)

2014-02-01

The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly 'gray' law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that

Effect of Flyash Addition on Mechanical and Gamma Radiation Shielding Properties of Concrete

Directory of Open Access Journals (Sweden)

Kanwaldeep Singh

2014-01-01

Full Text Available Six concrete mixtures were prepared with 0%, 20%, 30%, 40%, 50%, and 60% of flyash replacing the cement content and having constant water to cement ratio. The testing specimens were casted and their mechanical parameters were tested experimentally in accordance with the Indian standards. Results of mechanical parameters show their improvement with age of the specimens and results of radiation parameters show no significant effect of flyash substitution on mass attenuation coefficient.

MRI-guided attenuation correction in whole-body PET/MR. Assessment of the effect of bone attenuation

International Nuclear Information System (INIS)

Akbarzadeh, A.; Ay, M.R.; Ahmadian, A.; Riahi Alam, N.; Zaidi, H.

2013-01-01

Hybrid positron emission tomography (PET)/MRI presents many advantages in comparison with its counterpart PET/CT in terms of improved soft-tissue contrast, decrease in radiation exposure, and truly simultaneous and multi-parametric imaging capabilities. However, the lack of well-established methodology for MR-based attenuation correction is hampering further development and wider acceptance of this technology. We assess the impact of ignoring bone attenuation and using different tissue classes for generation of the attenuation map on the accuracy of attenuation correction of PET data. This work was performed using simulation studies based on the XCAT phantom and clinical input data. For the latter, PET and CT images of patients were used as input for the analytic simulation model using realistic activity distributions where CT-based attenuation correction was utilized as reference for comparison. For both phantom and clinical studies, the reference attenuation map was classified into various numbers of tissue classes to produce three (air, soft tissue and lung), four (air, lungs, soft tissue and cortical bones) and five (air, lungs, soft tissue, cortical bones and spongeous bones) class attenuation maps. The phantom studies demonstrated that ignoring bone increases the relative error by up to 6.8% in the body and up to 31.0% for bony regions. Likewise, the simulated clinical studies showed that the mean relative error reached 15% for lesions located in the body and 30.7% for lesions located in bones, when neglecting bones. These results demonstrate an underestimation of about 30% of tracer uptake when neglecting bone, which in turn imposes substantial loss of quantitative accuracy for PET images produced by hybrid PET/MRI systems. Considering bones in the attenuation map will considerably improve the accuracy of MR-guided attenuation correction in hybrid PET/MR to enable quantitative PET imaging on hybrid PET/MR technologies. (author)

Radiation-induced pulmonary gene expression changes are attenuated by the CTGF antibody Pamrevlumab.

Science.gov (United States)

Sternlicht, Mark D; Wirkner, Ute; Bickelhaupt, Sebastian; Lopez Perez, Ramon; Tietz, Alexandra; Lipson, Kenneth E; Seeley, Todd W; Huber, Peter E

2018-01-18

Fibrosis is a delayed side effect of radiation therapy (RT). Connective tissue growth factor (CTGF) promotes the development of fibrosis in multiple settings, including pulmonary radiation injury. To better understand the cellular interactions involved in RT-induced lung injury and the role of CTGF in these responses, microarray expression profiling was performed on lungs of irradiated and non-irradiated mice, including mice treated with the anti-CTGF antibody pamrevlumab (FG-3019). Between group comparisons (Welch's t-tests) and principal components analyses were performed in Genespring. At the mRNA level, the ability of pamrevlumab to prolong survival and ameliorate RT-induced radiologic, histologic and functional lung deficits was correlated with the reversal of a clear enrichment in mast cell, macrophage, dendritic cell and mesenchymal gene signatures. Cytokine, growth factor and matrix remodeling genes that are likely to contribute to RT pneumonitis and fibrosis were elevated by RT and attenuated by pamrevlumab, and likely contribute to the cross-talk between enriched cell-types in injured lung. CTGF inhibition had a normalizing effect on select cell-types, including immune cells not typically regarded as being regulated by CTGF. These results suggest that interactions between RT-recruited cell-types are critical to maintaining the injured state; that CTGF plays a key role in this process; and that pamrevlumab can ameliorate RT-induced lung injury in mice and may provide therapeutic benefit in other immune and fibrotic disorders.

Assessment of Radiation-Attenuated Vaccine or Thyme Oil Treatment on Controlling DNA Damage and Nitric Oxide Synthesis in Brain of Rat Infected with Toxocara canis

International Nuclear Information System (INIS)

Amin, M.M.; Hafez, E.N.; Abd Raboo, M.A.

2016-01-01

Toxocara canis is a worldwide zoonotic roundworm that infects a number of hosts including humans. It exhibits marked affinity to the nervous tissues. This study deals with the changes in the brain of Toxocara canis infected rats regarding parasitological, nitric oxide (NO) level and DNA damage compared to the effect of vaccination with gamma radiation-attenuated embryonated egg or thyme oil treatment. Eighty rats were classified into four groups (twenty each): GI (normal control); GII infected with 2500 T. canis infective eggs/ml/rat (infected control); GIII vaccinated with 800 Gy gamma-attenuated embryonated eggs (vaccinated group) and GIV infected with 2500 T. canis eggs and treated with thyme oil (thyme treated group). At the 14th day post-infection, ten rats from each group were sacrificed and the remaining were re-infected (challenged) with the same number of eggs. At the 14th days post challenge, brain tissues were taken for larval recovery, nitric oxide level evaluation and DNA damage using fragmentation and comet assay. The results exhibited a significant decrease in larval count and nitric oxide level with less damage in brain cells in thyme treated and gamma radiation-attenuated vaccinated groups compared to control infected group. It is also, concluded that vaccination using γ- rays is more effective in protection compared to using thyme oil.

Radiation protection clothes in X-ray-diagnostics. Comparison of test methods

International Nuclear Information System (INIS)

Pichler, T.; Schoepf, T.; Ennemoser, O.

2009-01-01

For testing the attenuation of the protection clothes the standard EN 61331-1 for attenuation measurements in the ''narrow and broad beam'' is available as well as the DIN 6857-1 for determination of shielding properties in the so called ''inverse broad-beam geometry''. The attenuation measurements in the narrow beam don't consider scattered radiation and fluorescence due to the arrangement. This leads to the fact that the protective effect of lead-free-Materials will be miss-estimated when compared to lead. In this work the measurements of shielding properties in inverse broad-beam geometry according to the DIN 6857-1 were compared with attenuation measurements according to the EN 61331-1. Also the dependence of the chamber was studied. Attenuation measurements were performed with lead- and lead-free-materials. Additional certificated lead-foils with high purity and precise thickness of 0.1 to 2 mm were used. For measuring a cylinder chamber of 30 cm 3 and two flat chambers of 75 cm 3 (SFD) and 112 cm 3 (FC) were used. The measurements in inverse broad-beam geometry according to the DIN 6857-1 show adequate results, also in testing lead-free protection materials. The results in attenuation correspond to a large extent to those, which are determined by measurements in the broad beam. When performing measurements in inverse geometry however the characteristic of the used chamber is not negligible. (orig.)

Modeling Optical and Radiative Properties of Clouds Constrained with CARDEX Observations

Science.gov (United States)

Mishra, S. K.; Praveen, P. S.; Ramanathan, V.

2013-12-01

Carbonaceous aerosols (CA) have important effects on climate by directly absorbing solar radiation and indirectly changing cloud properties. These particles tend to be a complex mixture of graphitic carbon and organic compounds. The graphitic component, called as elemental carbon (EC), is characterized by significant absorption of solar radiation. Recent studies showed that organic carbon (OC) aerosols absorb strongly near UV region, and this faction is known as Brown Carbon (BrC). The indirect effect of CA can occur in two ways, first by changing the thermal structure of the atmosphere which further affects dynamical processes governing cloud life cycle; secondly, by acting as cloud condensation nuclei (CCN) that can change cloud radiative properties. In this work, cloud optical properties have been numerically estimated by accounting for CAEDEX (Cloud Aerosol Radiative Forcing Dynamics Experiment) observed cloud parameters and the physico-chemical and optical properties of aerosols. The aerosol inclusions in the cloud drop have been considered as core shell structure with core as EC and shell comprising of ammonium sulfate, ammonium nitrate, sea salt and organic carbon (organic acids, OA and brown carbon, BrC). The EC/OC ratio of the inclusion particles have been constrained based on observations. Moderate and heavy pollution events have been decided based on the aerosol number and BC concentration. Cloud drop's co-albedo at 550nm was found nearly identical for pure EC sphere inclusions and core-shell inclusions with all non-absorbing organics in the shell. However, co-albedo was found to increase for the drop having all BrC in the shell. The co-albedo of a cloud drop was found to be the maximum for all aerosol present as interstitial compare to 50% and 0% inclusions existing as interstitial aerosols. The co-albedo was found to be ~ 9.87e-4 for the drop with 100% inclusions existing as interstitial aerosols externally mixed with micron size mineral dust with 2

Effect of ionizing radiation on the properties of PLA packaging materials

International Nuclear Information System (INIS)

Melski, K.; Kubera, H.; Gluszewski, W.; Zimek, Z.

2011-01-01

Poly(lactic acid) (PLA) is attractive as a substitute for classical polymer packaging material due to its biodegradability and sufficient mechanical and barrier properties. Presented research was focused on the changes of basic mechanical parameters after ionizing irradiation performed with doses in the range of 2.5-25 kGy, commonly used in radiation sterilization and preservation of foods. Two commercial available PLA packaging films were tested. The influence of radiation dose on the mechanical properties - tensile strength and elongation were determined using standardized methods. Radiation resistance of PLA is sufficient for packaging applications. The investigations of gas products of radiolysis of PLA have been made by gas chromatography after electron beam (EB) irradiations. (authors)

Investigation of radiation keeping property of barite coated cloth via image processing method

Science.gov (United States)

Kilinçarslan, Ş.; Akkurt, İ.; Molla, T.; Akarslan, F.

2012-09-01

Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

Investigation of radiation keeping property of barite coated cloth via image processing method

Energy Technology Data Exchange (ETDEWEB)

Kilincarslan, S.; Akkurt, I.; Molla, T.; Akarslan, F. [Department of Construction Education, Suleyman Demirel University, Isparta (Turkey); Department of Physics, Science Faculty, Suleyman Demirel University, Isparta (Turkey); Department of Construction Education, Suleyman Demirel University, Isparta (Turkey); Textil Engineering, Engineering Faculty, Suleyman Demirel University, Isparta (Turkey)

2012-09-06

Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

Investigation of radiation keeping property of barite coated cloth via image processing method

International Nuclear Information System (INIS)

Kilinçarslan, Ş.; Akkurt, İ.; Molla, T.; Akarslan, F.

2012-01-01

Preservative clothes which are able to absorb radiation beam are needed not only for saving people working at radioactive environment but also for saving others from natural and man-made radiation sources we are exposed in daily life. Barite is a mineral which can be used for armour plating because of high atomic numbered element barium constituent of barite. In this study, armour plating property of barite was applied to fabrics. Barite coated fabric having characteristic of keeping radiation was obtained by penetrating barite on cloth via coating method. Radiation keeping property of fabrics obtained was determined via image processing. The results of experiments showed that barite coated fabrics have blocked radiation more than normal fabrics have done.

Effects of γ-radiation on the properties of insulating oil

International Nuclear Information System (INIS)

Abdel Aziz, M.M.; Elshazly-Zaghloul, M.; Zaghloul, A.R.M.; Fikry, L.; Raieh, M.

1986-01-01

Electrical Equipment used in an irradiated environment suffer from ionization and other effects. Insulating oil, e.g. of transformers, in a nuclear power station is subjected to γ-radiation. In this communication we provide a detailed experimental study of insulating oil subjected to γ-radiation. Unused oil samples of the type used in Egypt were subjected to γ-radiation for different time periods. The electrical properties of these samples are measured; dielectric constant and breakdown strength

The influence of gamma radiation on HDPE properties for tibial tray

International Nuclear Information System (INIS)

Sulistioso, G.S.; Dewi, R.K.; Maria, C.P.; Nada, M.

2012-01-01

A research on HDPE as tibial tray in total knee joint replacement surgery has been done. The aims of this research were to characterize the influence of gamma radiation on chemical, and mechanical properties on HDPE is made by using hot press method then irradiated with various doses of gamma rays of 0 kGy, 25 kGy, 50 kGy, 75 kGy, 100 kGy, 125 kGy, and 150 kGy at a dose rate 9 kGy/h. The irradiated HDPE were tested for their chemical, and mechanical properties. The chemical properties test, involve crosslinking and free radicals. The mechanical properties test, involve hardness, tensile strength, and elongation at break. The results showed that gamma radiation from IRKA IV th category can enhance the, chemical properties of HDPE in terms of percentage and number of radical crosslinking and mechanical properties of HDPE in terms of hardness, tensile strength and elongation at break with different changes from the initial state before radiation also the optimum dose to obtain better physical, chemical, and mechanical properties of HDPE, crosslinking percentage at 99.71%; height of radical peroxide curve at 13 cm; hardness (shore A) at 94.33; modulus of elasticity at 1113.03 N/mm 2 ; yield stress at 26.38 N/mm 2 ; tensile strength at 31.11 N/mm 2 ; and elongation at break at 440.37%, so that HDPE can be used as tibial tray. (author)

Gamma-ray mass attenuation coefficient and half value layer factor of some oxide glass shielding materials

International Nuclear Information System (INIS)

Waly, El-Sayed A.; Fusco, Michael A.; Bourham, Mohamed A.

2016-01-01

The variation in dosimetric parameters such as mass attenuation coefficient, half value layer factor, exposure buildup factor, and the photon mean free path for different oxide glasses for the incident gamma energy range 0.015–15 MeV has been studied using MicroShield code. It has been inferred that the addition of PbO and Bi 2 O 3 improves the gamma ray shielding properties. Thus, the effect of chemical composition on these parameters is investigated in the form of six different glass compositions, which are compared with specialty concrete for nuclear radiation shielding. The composition termed ‘Glass 6’ in this paper has the highest mass attenuation and the smallest half value layer and may have potential applications in radiation shielding. An example dry storage cask utilizing an additional layer of Glass 6 as an intermediate shielding layer, simulated in MicroShield, is capable of reducing the exposure rate at the cask surface by over 20 orders of magnitude compared to the case without a glass layer. Based on this study, Glass 6 shows promise as a gamma-ray shielding material, particularly for dry cask storage.

Calculation of the radiative properties of photosynthetic microorganisms

International Nuclear Information System (INIS)

Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard

2015-01-01

A generic methodological chain for the predictive calculation of the light-scattering and absorption properties of photosynthetic microorganisms within the visible spectrum is presented here. This methodology has been developed in order to provide the radiative properties needed for the analysis of radiative transfer within photobioreactor processes, with a view to enable their optimization for large-scale sustainable production of chemicals for energy and chemistry. It gathers an electromagnetic model of light-particle interaction along with detailed and validated protocols for the determination of input parameters: morphological and structural characteristics of the studied microorganisms as well as their photosynthetic-pigment content. The microorganisms are described as homogeneous equivalent-particles whose shape and size distribution is characterized by image analysis. The imaginary part of their refractive index is obtained thanks to a new and quite extended database of the in vivo absorption spectra of photosynthetic pigments (that is made available to the reader). The real part of the refractive index is then calculated by using the singly subtractive Kramers–Krönig approximation, for which the anchor point is determined with the Bruggeman mixing rule, based on the volume fraction of the microorganism internal-structures and their refractive indices (extracted from a database). Afterwards, the radiative properties are estimated using the Schiff approximation for spheroidal or cylindrical particles, as a first step toward the description of the complexity and diversity of the shapes encountered within the microbial world. Finally, these predictive results are confronted to experimental normal-hemispherical transmittance spectra for validation. This entire procedure is implemented for Rhodospirillum rubrum, Arthrospira platensis and Chlamydomonas reinhardtii, each representative of the main three kinds of photosynthetic microorganisms, i.e. respectively

Calculation of the radiative properties of photosynthetic microorganisms

Science.gov (United States)

Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard

2015-08-01

A generic methodological chain for the predictive calculation of the light-scattering and absorption properties of photosynthetic microorganisms within the visible spectrum is presented here. This methodology has been developed in order to provide the radiative properties needed for the analysis of radiative transfer within photobioreactor processes, with a view to enable their optimization for large-scale sustainable production of chemicals for energy and chemistry. It gathers an electromagnetic model of light-particle interaction along with detailed and validated protocols for the determination of input parameters: morphological and structural characteristics of the studied microorganisms as well as their photosynthetic-pigment content. The microorganisms are described as homogeneous equivalent-particles whose shape and size distribution is characterized by image analysis. The imaginary part of their refractive index is obtained thanks to a new and quite extended database of the in vivo absorption spectra of photosynthetic pigments (that is made available to the reader). The real part of the refractive index is then calculated by using the singly subtractive Kramers-Krönig approximation, for which the anchor point is determined with the Bruggeman mixing rule, based on the volume fraction of the microorganism internal-structures and their refractive indices (extracted from a database). Afterwards, the radiative properties are estimated using the Schiff approximation for spheroidal or cylindrical particles, as a first step toward the description of the complexity and diversity of the shapes encountered within the microbial world. Finally, these predictive results are confronted to experimental normal-hemispherical transmittance spectra for validation. This entire procedure is implemented for Rhodospirillum rubrum, Arthrospira platensis and Chlamydomonas reinhardtii, each representative of the main three kinds of photosynthetic microorganisms, i.e. respectively

Variability in dynamic properties of tantalum : spall, attenuation and load/unload.

Energy Technology Data Exchange (ETDEWEB)

Furnish, Michael David; Reinhart, William Dodd; Trott, Wayne Merle; Vogler, Tracy John; Chhabildas, Lalit Chandra

2005-07-01

A suite of impact experiments was conducted to assess spatial and shot-to-shot variability in dynamic properties of tantalum. Samples had a uniform refined {approx}20 micron grain structure with a strong axisymmetric [111] crystallographic texture. Two experiments performed with sapphire windows (stresses of approximately 7 and 12 GPa) clearly showed elastic-plastic loading and slightly hysteretic unloading behavior. An HEL amplitude of 2.8 GPa (corresponding to Y 1.5 GPa) was observed. Free-surface spall experiments showed clear wave attenuation and spallation phenomena. Here, loading stresses were {approx} 12.5 GPa and various ratios of impactor to target thicknesses were used. Spatial and shot-to-shot variability of the spall strength was {+-} 20%, and of the HEL, {+-} 10%. Experiments conducted with smaller diameter flyer plates clearly showed edge effects in the line and point VISAR records, indicating lateral release speeds of roughly 5 km/s.

Cosmic radiation shielding properties of COLUMBUS and REMSIM multi-layer external shells

Science.gov (United States)

Durante, Marco; Manti, Lorenzo; Rusek, Adam; Belluco, Maurizio; Lobascio, Cesare

The European module COLUMBUS has been recently installed on the International Space Station. Future plans for exploration involve the use of inflatable modules, such as the REMSIM concept proposed in a previous ESA funded study. We studied the radiation shielding properties of COLUMBUS and REMSIM external shell using 1 GeV/n Feor H-ions accelerated at the NASA Space Radiation Laboratory at the Brookhaven National Laboratory (Long Island, NY, USA). COLUMBUS has a 22 mm rigid multi-layer shell with Al, Nextel and Kevlar, as materials of the double bumper for meteoroids and debris protection, MLI for thermal reasons and again Al as pressure shell. Inside the module, astronauts are further protected by secondary structures, including racks, a number of electronic devices and payload equipment. This internal equipment has been simulated using Al and Kevlar, bringing the total thickness to about 15 g/cm2. REMSIM consists of a thermal multi-layer (MLI), four Nextel layers used to provide shock of the impacting micro-meteoroids, a ballistic restraint multi-layer of Kevlar used to absorb debris cloud's kinetic energy, a Kevlar structural restraint to support pressure loads incurred from inflating the module. To contain air inside the module, REMSIM adopts three layers of airtight material separated by two layers of Kevlar (air bladder). A final layer of Nomex provide protection against punctures and fire. In the flight configuration there are also spacer elements (foam) needed to guarantee correct spacing between consecutive bumper layers. These spacers were not included in the tests, making the total thickness about 1.1 cm. The internal equipment in REMSIM was not been defined, but due to its application for exploration missions it was decided to exploit water, valuable resource used for drinking, washing and technical usage, as a radiation shielding. In this test, we have included about 8 cm of water. Measured dose attenuation shows that the Columbus module reduces the

Radiation damage in optical fibers

International Nuclear Information System (INIS)

Lyons, P.B.; Looney, L.D.; Ogle, J.W.

1983-01-01

Optical fibers provide important advantages over coaxial cables for many data transmission applications. Some of these applications require that the fibers transmit data during a radiation pulse. Other applications utilize the fiber as a radiation-to-light transducer. In either case, radiation-induced luminescence and absorption must be understood. Most studies of radiation effects in fibers have emphasized time scales of interest in telecommunication systems, from the msec to hour range. Few studies have concentrated on response at times below 1 + s. At Los Alamos, both laboratory electron accelerators and nuclear tests have been used as radiation sources to probe this early time region. The use of a fiber (or any optical medium) as a Cerenkov radiation-to-light transducer is discussed. Since the radiation induces attenuation in the medium, the light output is not proportional to the radiation input. The nonlinearity introduced by this attenuation is calculated

γ-ray radiation effect on properties of straw powder/PBS composite

International Nuclear Information System (INIS)

Yang Mingcheng; Luo Yongquan; Liu Wentao; Zhu Jun; Guo Dongquan; Li Zhaopeng; Gen Feng; Qu Lingbo

2013-01-01

Background: In recent years, with decreasing global fossil resources and increasing 'white pollution', renewable and biodegradable materials attract more and more attentions. Poly (butylene succinate) (PBS) has good mechanical property, biodegradability and processing performance, which is the focus of hot topics in the study of biodegradable plastic materials, however, being soft and of high cost, it is still limited in application range. Purpose: In order to improve the mechanical and thermal properties, a series of wheat straw powder/PBS composites were prepared by melt extrusion, and then the 60 Co-y ray was directly utilized to irradiate the straw powder/PBS composite. Methods: The influence of TAIC (triallyl isocyanurate) radiation absorbed dose and radiation sensitizer on the mechanical property and thermal performance of straw powder/PBS composite was investigated, and the impact fracture surface morphology of the composite was observed by SEM (scanning electron microscope). Results: The tensile strength and flexural strength were enhanced with increasing radiation dosage, and then tend to be stable, the heat distortion temperature also increased but not significantly with increasing radiation dosage. The results show that when TAIC content is 2%, with straw powder/PBS composite irradiated by 30-kGy dose, the tensile strength and flexural strength are increased by 26% and 39.8%, respectively. Conclusion: The radiation modification of composite material has no effect on thermal stability, but do improve the tensile strength and flexural strength when up to 2% of TAIC is integrated and irradiated by certain dose. The interface cohesiveness between straw powder and PBS is strengthened after radiation. (authors)

Protection from radiation injury through oral administration of PF4 gene carried by attenuated salmonella

International Nuclear Information System (INIS)

Zhao Lihua; Liu Bin; Yu Xiaofei; Zhang Lei; Han Zhongchao

2005-01-01

Objective: To investigate the in vivo radiation protection effect of PF4 by oral administration of attenuated salmonella as the carrier in mice. Methods: The eukaryotic vector pIRES2-EGFP-carried PF4 gene was transferred into an aroA-autotrophic mutant of salmonella typhimurium (SL3261), which was administered orally to BALBPc mice at 1x10 8 PFu once every interval three days. At 12 hours after the third oral administration the mice were subjected to a total body irradiation (TBI) of 700 cGy by a 60 Co source. The protective effect of SL3261/PF4 was determined by detection GFP ( green fluorescence protein) expression in tissues, peripheral blood count, culture of bone marrow colony-forming cells and survival time of mice. Results: Expression of GFP could be detected in the liver, spleen, intestine, kidney, peripheral blood and bone marrow. On days 7 and 14 after irradiation, Compared to controls, there were obvious differences in number of bone marrow mononuclear cells, CFU-GM (granulocyte-macrophage colony-forming unit ) and HPP-CFC (high proliferating potential-colony-forming cells) of mice treated with SL3261/PF4 (P<0.05) as well as prolongation of the survival time. Conclusion: These data demonstrate for the first time that PF4 protects mice from TBI injury and accelerates recovery of hematopoiesis by oral administration of attenuated salmonella carrying PF4 gene. (authors)

Cloud Scavenging Effects on Aerosol Radiative and Cloud-nucleating Properties - Final Technical Report

Energy Technology Data Exchange (ETDEWEB)

Ogren, John A.; Sheridan, Patrick S.; Andrews, Elisabeth

2009-03-05

The optical properties of aerosol particles are the controlling factors in determining direct aerosol radiative forcing. These optical properties depend on the chemical composition and size distribution of the aerosol particles, which can change due to various processes during the particles’ lifetime in the atmosphere. Over the course of this project we have studied how cloud processing of atmospheric aerosol changes the aerosol optical properties. A counterflow virtual impactor was used to separate cloud drops from interstitial aerosol and parallel aerosol systems were used to measure the optical properties of the interstitial and cloud-scavenged aerosol. Specifically, aerosol light scattering, back-scattering and absorption were measured and used to derive radiatively significant parameters such as aerosol single scattering albedo and backscatter fraction for cloud-scavenged and interstitial aerosol. This data allows us to demonstrate that the radiative properties of cloud-processed aerosol can be quite different than pre-cloud aerosol. These differences can be used to improve the parameterization of aerosol forcing in climate models.

Effect of radiation-induced modification in fluoroelastomer

International Nuclear Information System (INIS)

Zen, Heloisa Augusto; Lugao, Ademar Benevolo

2013-01-01

Polymers exposed to ionizing irradiation, even at low doses, often undergo structural changes accompanied by molecular crosslinking and chain scission (degradation) reactions. The general effect of the radiation on polymers is determined by the ratio of crosslinking to chain scission events. This ratio depends on parameters such as chemical structure, physical state, radicals stability and mobility, irradiation rate and irradiation atmosphere. The radiation process is a large used technique to promote modification in their structures to apply them in different areas and is well known for its merits and potential in modifying the chemical and the physical properties of polymeric materials without cause drastic changes in their inherent properties, depend on the dose irradiated. In this study was used fluoroelastomer with 70% - fluor that having excellent thermal, chemical and mechanical properties. Vulcanized and non-vulcanized samples of this material were submitted to gamma radiation under air atmosphere in order to observe the effect of atmosphere in the polymer matrix. The irradiated doses were 5, 10 and 20kGy, at room temperature. The characterization was made by scanning electron microscope (SEM), infrared spectroscopy using attenuate reflectance (ATR-IR) and X-ray diffraction. The results demonstrated which was expected, the degradation reactions were observed. (author)

Radiation mitigating properties of the lignan component in flaxseed

International Nuclear Information System (INIS)

Pietrofesa, Ralph; Christofidou-Solomidou, Melpo; Turowski, Jason; Tyagi, Sonia; Dukes, Floyd; Arguiri, Evguenia; Busch, Theresa M; Gallagher-Colombo, Shannon M; Solomides, Charalambos C; Cengel, Keith A

2013-01-01

Wholegrain flaxseed (FS), and its lignan component (FLC) consisting mainly of secoisolariciresinol diglucoside (SDG), have potent lung radioprotective properties while not abrogating the efficacy of radiotherapy. However, while the whole grain was recently shown to also have potent mitigating properties in a thoracic radiation pneumonopathy model, the bioactive component in the grain responsible for the mitigation of lung damage was never identified. Lungs may be exposed to radiation therapeutically for thoracic malignancies or incidentally following detonation of a radiological dispersion device. This could potentially lead to pulmonary inflammation, oxidative tissue injury, and fibrosis. This study aimed to evaluate the radiation mitigating effects of FLC in a mouse model of radiation pneumonopathy. We evaluated FLC-supplemented diets containing SDG lignan levels comparable to those in 10% and 20% whole grain diets. 10% or 20% FLC diets as compared to an isocaloric control diet (0% FLC) were given to mice (C57/BL6) (n=15-30 mice/group) at 24, 48, or 72-hours after single-dose (13.5 Gy) thoracic x-ray treatment (XRT). Mice were evaluated 4 months post-XRT for blood oxygenation, lung inflammation, fibrosis, cytokine and oxidative damage levels, and survival. FLC significantly mitigated radiation-related animal death. Specifically, mice fed 0% FLC demonstrated 36.7% survival 4 months post-XRT compared to 60–73.3% survival in mice fed 10%-20% FLC initiated 24–72 hours post-XRT. FLC also mitigated radiation-induced lung fibrosis whereby 10% FLC initiated 24-hours post-XRT significantly decreased fibrosis as compared to mice fed control diet while the corresponding TGF-beta1 levels detected immunohistochemically were also decreased. Additionally, 10-20% FLC initiated at any time point post radiation exposure, mitigated radiation-induced lung injury evidenced by decreased bronchoalveolar lavage (BAL) protein and inflammatory cytokine/chemokine release at 16 weeks

Developing light nano-composites with improved mechanical properties for neutron shielding

Energy Technology Data Exchange (ETDEWEB)

Jamali, F. [Shiraz Univ. of Medical Sciences (Iran, Islamic Republic of). School of Medicine; Mortazavi, S.M.J. [Shiraz Univ. of Medical Sciences (Iran, Islamic Republic of). Dept. of Medical Physics and Medical Engineering; Shiraz Univ. of Medical Sciences (Iran, Islamic Republic of). The Center for Radiological Research; Kardan, M. [Nuclear Science and Technology Institute, Tehran (Iran, Islamic Republic of). Radiation Application School; Mosleh-Shirazi, M.A. [Shiraz Univ. of Medical Sciences (Iran, Islamic Republic of). Radiotherapy Dept.; Sina, S. [Shiraz Univ. of Medical Sciences (Iran, Islamic Republic of). Radiation Research Center; Rahpeyma, J.

2017-12-15

Although radiation exposures in manned space missions are normally below the limits recommended to NASA by NCRP, in long-duration deep space exploratory missions astronauts may receive relatively high doses of ionizing radiation. Novel light polyethylene-based composites can be considered as effective radiation shields in space explorations. However, normally these composites cannot provide desired mechanical properties. Over the past several years our laboratories have focused on developing efficient methods for both physical and biological protection of the crew in long term space missions. In this study carbon nanotubes and either nano-sized or micro-sized boron carbide (B{sub 4}C) fillers were incorporated into the continuous phase of low density polyethylene (LDPE). In the next phase, the mechanical characteristics of the composites as well as their neutron attenuation properties were studied. Findings of this study indicated enhanced mechanical properties accompanied by an enhanced shielding efficiency for neutrons at some specific weight fraction of the fillers.

Statistical and coherence properties of radiation from X-ray free electron lasers

International Nuclear Information System (INIS)

Saldin, E.L.; Schneidmiller, E.A.; Yurkov, M.V.

2009-12-01

We describe statistical and coherence properties of the radiation from X-ray free electron lasers (XFEL). It is shown that the X-ray FEL radiation before saturation is described with gaussian statistics. Particularly important is the case of the optimized X-ray FEL, studied in detail. Applying similarity techniques to the results of numerical simulations allowed us to find universal scaling relations for the main characteristics of an X-ray FEL operating in the saturation regime: efficiency, coherence time and degree of transverse coherence. We find that with an appropriate normalization of these quantities, they are functions of only the ratio of the geometrical emittance of the electron beam to the radiation wavelength. Statistical and coherence properties of the higher harmonics of the radiation are highlighted as well. (orig.)

Statistical and coherence properties of radiation from X-ray free electron lasers

Energy Technology Data Exchange (ETDEWEB)

Saldin, E L; Schneidmiller, E A; Yurkov, M V

2009-12-15

We describe statistical and coherence properties of the radiation from X-ray free electron lasers (XFEL). It is shown that the X-ray FEL radiation before saturation is described with gaussian statistics. Particularly important is the case of the optimized X-ray FEL, studied in detail. Applying similarity techniques to the results of numerical simulations allowed us to find universal scaling relations for the main characteristics of an X-ray FEL operating in the saturation regime: efficiency, coherence time and degree of transverse coherence. We find that with an appropriate normalization of these quantities, they are functions of only the ratio of the geometrical emittance of the electron beam to the radiation wavelength. Statistical and coherence properties of the higher harmonics of the radiation are highlighted as well. (orig.)

Action of an ionizing radiation and hydrodynamic effect on matrix properties of DNA during extracellular synthesis of RNA, and thiophosphate protection of matrix properties of T2-DNA against. gamma. -radiation. [gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Shekhtman, Ya L; Domashenko, A D; Kamzolova, S G; Medvedkov, A A [AN SSSR, Pushchino-na-Oke. Inst. Biologicheskoj Fiziki

1976-05-01

Action of an ionizing radiation and the hydrodynamic effect of the matrix activity of thymus DNA and T2 phase DNA have been studied in vitro in the RNA: polymerase system of E.coli B. Also studied have been the thiophosphate protection of matrix properties of T2-DNA against ..gamma..-radiation.

Use of two monoenergetic gamma-ray attenuation method in wood samples

International Nuclear Information System (INIS)

Mortatti, J.; Nascimento Filho, V.F. do; Barros Ferraz, E.S. de

1983-01-01

The mass attenuation coefficients for 10 wood species were determined employing the gamma attenuation technique with a single beam comprising two monoenergetics gamma energies from 137 Cs/sup(137m) Ba and 141 Am (662 and 59,6 KeV, respectively). The absorbed radiation was simultaneously measured by means of a 3'' x 3'' Nal (T1) planar solid scintillator crystal connected to a two channel gamma spectrometer. The effect of the 137 Cs/ sup(137m) Ba compton radiation on the not 241 Am counting rates were corrected. Dead time effects were desregarded, as the counting rates were always below 10 5 cpm. (Author) [pt

Assembly of gamma radiation detection with directivity properties

International Nuclear Information System (INIS)

Stoica, M.; Talpalariu, C.

2016-01-01

An assembly of gamma radiation detection with directivity properties and small size enables the development of portable equipment or robots specialized in finding and signaling radioactively contaminated areas in case of nuclear incidents or decommissioning of nuclear installations. Directivity characteristic of the assembly of gamma radiation detection is very important when aiming to build an equipment for searching radioactively contaminated areas. In order to obtain a suitable directivity characteristics in terms of detection of gamma rays, it was necessary to construct a lead collimator with a cylindrical shape. The detector, preamplifier and amplifier pulse were placed inside the collimator and pulse discriminator circuit and power source were placed beside the collimator, all being disposed within the housing cylindrical experimental. A PIN photodiode type was used as a detector of gamma radiation. (authors)

Versatile radiation gaging system

International Nuclear Information System (INIS)

Long, P.J.

1978-01-01

The attributes of computerized versatile radiation gaging systems are described. The gages are used to measure plating thicknesses and material characteristics that can be determined from radiation attenuation and/or x-ray fluorescence measurements

Attenuation-based automatic kilovolt (kV)-selection in computed tomography of the chest: effects on radiation exposure and image quality.

Science.gov (United States)

Eller, Achim; Wuest, Wolfgang; Scharf, Michael; Brand, Michael; Achenbach, Stephan; Uder, Michael; Lell, Michael M

2013-12-01

To evaluate an automated attenuation-based kV-selection in computed tomography of the chest in respect to radiation dose and image quality, compared to a standard 120 kV protocol. 104 patients were examined using a 128-slice scanner. Fifty examinations (58 ± 15 years, study group) were performed using the automated adaption of tube potential (100-140 kV), based on the attenuation profile of the scout scan, 54 examinations (62 ± 14 years, control group) with fixed 120 kV. Estimated CT dose index (CTDI) of the software-proposed setting was compared with a 120 kV protocol. After the scan CTDI volume (CTDIvol) and dose length product (DLP) were recorded. Image quality was assessed by region of interest (ROI) measurements, subjective image quality by two observers with a 4-point scale (3--excellent, 0--not diagnostic). The algorithm selected 100 kV in 78% and 120 kV in 22%. Overall CTDIvol reduction was 26.6% (34% in 100 kV) overall DLP reduction was 22.8% (32.1% in 100 kV) (all pimage quality was excellent in both groups. The attenuation based kV-selection algorithm enables relevant dose reduction (~27%) in chest-CT while keeping image quality parameters at high levels. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Attenuation-based automatic kilovolt (kV)-selection in computed tomography of the chest: Effects on radiation exposure and image quality

Energy Technology Data Exchange (ETDEWEB)

Eller, Achim; Wuest, Wolfgang; Scharf, Michael; Brand, Michael [Department of Radiology, University Erlangen (Germany); Achenbach, Stephan [Department of Cardiology, University Erlangen (Germany); Uder, Michael [Department of Radiology, University Erlangen (Germany); Imaging Science Institute, Erlangen (Germany); Lell, Michael M., E-mail: Michael.lell@uk-erlangen.de [Department of Radiology, University Erlangen (Germany); Imaging Science Institute, Erlangen (Germany)

2013-12-01

Objectives: To evaluate an automated attenuation-based kV-selection in computed tomography of the chest in respect to radiation dose and image quality, compared to a standard 120 kV protocol. Materials and methods: 104 patients were examined using a 128-slice scanner. Fifty examinations (58 ± 15 years, study group) were performed using the automated adaption of tube potential (100–140 kV), based on the attenuation profile of the scout scan, 54 examinations (62 ± 14 years, control group) with fixed 120 kV. Estimated CT dose index (CTDI) of the software-proposed setting was compared with a 120 kV protocol. After the scan CTDI volume (CTDIvol) and dose length product (DLP) were recorded. Image quality was assessed by region of interest (ROI) measurements, subjective image quality by two observers with a 4-point scale (3 – excellent, 0 – not diagnostic). Results: The algorithm selected 100 kV in 78% and 120 kV in 22%. Overall CTDIvol reduction was 26.6% (34% in 100 kV) overall DLP reduction was 22.8% (32.1% in 100 kV) (all p < 0.001). Subjective image quality was excellent in both groups. Conclusion: The attenuation based kV-selection algorithm enables relevant dose reduction (∼27%) in chest-CT while keeping image quality parameters at high levels.

Attenuation-based automatic kilovolt (kV)-selection in computed tomography of the chest: Effects on radiation exposure and image quality

International Nuclear Information System (INIS)

Eller, Achim; Wuest, Wolfgang; Scharf, Michael; Brand, Michael; Achenbach, Stephan; Uder, Michael; Lell, Michael M.

2013-01-01

Objectives: To evaluate an automated attenuation-based kV-selection in computed tomography of the chest in respect to radiation dose and image quality, compared to a standard 120 kV protocol. Materials and methods: 104 patients were examined using a 128-slice scanner. Fifty examinations (58 ± 15 years, study group) were performed using the automated adaption of tube potential (100–140 kV), based on the attenuation profile of the scout scan, 54 examinations (62 ± 14 years, control group) with fixed 120 kV. Estimated CT dose index (CTDI) of the software-proposed setting was compared with a 120 kV protocol. After the scan CTDI volume (CTDIvol) and dose length product (DLP) were recorded. Image quality was assessed by region of interest (ROI) measurements, subjective image quality by two observers with a 4-point scale (3 – excellent, 0 – not diagnostic). Results: The algorithm selected 100 kV in 78% and 120 kV in 22%. Overall CTDIvol reduction was 26.6% (34% in 100 kV) overall DLP reduction was 22.8% (32.1% in 100 kV) (all p < 0.001). Subjective image quality was excellent in both groups. Conclusion: The attenuation based kV-selection algorithm enables relevant dose reduction (∼27%) in chest-CT while keeping image quality parameters at high levels

Measurement of Thermal Radiation Properties of Solids

Science.gov (United States)

Richmond, J. C. (Editor)

1963-01-01

The overall objectives of the Symposium were to afford (1) an opportunity for workers in the field to describe the equipment and procedures currently in use for measuring thermal radiation properties of solids, (2) an opportunity for constructive criticism of the material presented, and (3) an open forum for discussion of mutual problems. It was also the hope of the sponsors that the published proceedings of the Symposium would serve as a valuable reference on measurement techniques for evaluating thermal radiation properties of solids, partic.ularly for those with limited experience in the field. Because of the strong dependence of emitted flux upon temperature, the program committee thought it advisable to devote the first session to a discussion of the problems of temperature measurement. All of the papers in Session I were presented at the request of and upon topics suggested by the Committee. Because of time and space limitations, it, was impossible to consider all temperature measurement problems that might arise--the objective was rather to call to the attention of the reader some of the problems that might be encountered, and to provide references that might provide solutions.

Measurement and evaluation of the radiative properties of a thin solid fuel

Science.gov (United States)

Pettegrew, Richard; Street, Kenneth; Pitch, Nancy; Tien, James; Morrison, Phillip

2003-01-01

Accurate modeling of combustion systems requires knowledge of the radiative properties of the system. Gas phase properties are well known, but detailed knowledge of surface properties is limited. Recent work has provided spectrally resolved data for some solid fuels, but only for the unburned material at room temperature, and for limited sets of previously burned and quenched samples. Due to lack of knowledge of the spectrally resolved properties at elevated temperatures, as well as processing limitations in the modeling effort, graybody values are typically used for the fuels surface radiative properties. However, the spectrally resolved properties for the fuels at room temperature can be used to give a first-order correction for temperature effects on the graybody values. Figure 1 shows a sample of the spectrally resolved emittance/absorptance for a thin solid fuel of the type commonly used in combustion studies, from approximately 2 to 20 microns. This plot clearly shows a strong spectral dependence across the entire range. By definition, the emittance is the ratio of the emitted energy to that of a blackbody at the same temperature. Therefore, to determine a graybody emittance for this material, the spectrally resolved data must be applied to a blackbody curve. The total area under the resulting curve is ratioed to the total area under the blackbody curve to yield the answer. Due to the asymmetry of the spectrally resolved emittance and the changing shape of the blackbody curve as the temperature increases, the relative importance of the emittance value at any given wavelength will change as a function of temperature. Therefore, the graybody emittance value for a given material will change as a function of temperature even if the spectral dependence of the radiative properties remains unchanged. This is demonstrated in Figures 2 and 3, which are plots of the spectrally resolved emittance for KimWipes (shown in Figure 1) multiplied by the blackbody curves for

Attenuated radon transform: theory and application in medicine and biology

Energy Technology Data Exchange (ETDEWEB)

Gullberg, G.T.

1979-06-01

A detailed analysis is given of the properties of the attenuated Radon transform and of how increases in photon attenuation influence the numerical accuracy and computation efficiency of iterative and convolution algorithms used to determine its inversion. The practical applications for this work involve quantitative assessment of the distribution of injected radiopharmaceuticals and radionuclides in man and animals for basic physiological and biochemical studies as well as clinical studies in nuclear medicine. A mathematical structure is developed using function theory and the theory of linear operators on Hilbert spaces which lends itself to better understanding the spectral properties of the attenuated Radon transform. The continuous attenuated Radon transform reduces to a matrix operator for discrete angular and lateral sampling, and the reconstruction problem reduces to a system of linear equations. For the situation of variable attenuation coefficient frequently found in nuclear medicine applications of imaging the heart and chest, the procedure developed in this thesis involves iterative techniques of performing the generalized inverse. For constant attenuation coefficient less than 0.15 cm/sup -1/, convolution methods can reliably reconstruct a 30 cm object with 0.5 cm resolution. However, for high attenuation coefficients or for the situation where there is variable attenuation such as reconstruction of distribution of isotopes in the heart, iterative techniques developed in this thesis give the best results. (ERB)

Experimental study on radiation resistant properties of seismic isolation elements

International Nuclear Information System (INIS)

Yoneda, G.; Nojima, O.; Aizawa, S.; Uchiyama, Y.; Ikenaga, M.; Yoshizawa, T.

1991-01-01

Recently, studies on the application of a seismic isolation system to a reactor building and or the equipment of a nuclear power plant has been carried out. This study aims at investigating the influence which is exerted upon the mechanical properties of the seismic isolation elements by radiation. The authors conducted irradiation tests, using γ rays, on natural rubber bearings (NRB), lead rubber bearings (LRB), high damping rubber bearings (HRB), and the viscous fluid used in viscous dampers. The maximum radiation intensity was 5 x 10 7 R (Roentgen). The comparison between the mechanical properties of each seismic isolation element before and after the irradiation test are reported in the following. (author)

Correlation of gamma ray shielding and structural properties of PbO–BaO–P{sub 2}O{sub 5} glass system

Energy Technology Data Exchange (ETDEWEB)

Kaur, Kulwinder; Singh, K.J., E-mail: kanwarjitsingh@yahoo.com; Anand, Vikas

2015-04-15

Highlights: • Transparent glass samples of the system 55PbO{sub x}BaO(45 − x)P{sub 2}O{sub 5} (x = 1 up to 5) have been prepared in the laboratory. • Gamma ray shielding properties improve with the addition of BaO. • Number of non-bridging oxygens decrease with the increase in the content of BaO. • Investigated glass system can be potential candidate as an alternate to conventional radiation shielding ‘concrete’. - Abstract: The presented work has been undertaken to evaluate the applicability of BaO doped PbO-P{sub 2}O{sub 5} glass system as gamma ray shielding material in terms of mass attenuation coefficient and half value layer at photon energies 662, 1173 and1332 keV. A meaningful comparison of their radiation shielding properties has been made in terms of their mass attenuation coefficient and HVL parameters with standard radiation shielding concrete ‘barite’. The density, molar volume, XRD, FTIR, Raman and UV–visible techniques and mechanical properties (by Yamane and Mackenzie's procedure) have been used to study the structural properties of the prepared glass system in order to check the possibility of their commercial utility as alternate to conventional concrete for gamma ray shielding applications.

The Ultraviolet Attenuation Law in Backlit Spiral Galaxies

Science.gov (United States)

Keel, William C.; Manning, Anna M.; Holwerda, Benne W.; Lintott, Chris J.; Schawinski, Kevin

2014-02-01

The effective extinction law (attenuation behavior) in galaxies in the emitted ultraviolet (UV) regime is well known only for actively star-forming objects and combines effects of the grain properties, fine structure in the dust distribution, and relative distributions of stars and dust. We use Galaxy Evolution Explorer, XMM Optical Monitor, and Hubble Space Telescope (HST) data to explore the UV attenuation in the outer parts of spiral disks which are backlit by other UV-bright galaxies, starting with the candidate list of pairs provided by Galaxy Zoo participants. New optical images help to constrain the geometry and structure of the target galaxies. Our analysis incorporates galaxy symmetry, using non-overlapping regions of each galaxy to derive error estimates on the attenuation measurements. The entire sample has an attenuation law across the optical and UV that is close to the Calzetti et al. form; the UV slope for the overall sample is substantially shallower than found by Wild et al., which is a reasonable match to the more distant galaxies in our sample but not to the weighted combination including NGC 2207. The nearby, bright spiral NGC 2207 alone gives an accuracy almost equal to the rest of our sample, and its outer arms have a very low level of foreground starlight. Thus, this widespread, fairly "gray" law can be produced from the distribution of dust alone, without a necessary contribution from differential escape of stars from dense clouds. Our results indicate that the extrapolation needed to compare attenuation between backlit galaxies at moderate redshifts from HST data, and local systems from Sloan Digital Sky Survey and similar data, is mild enough to allow the use of galaxy overlaps to trace the cosmic history of dust in galaxies. For NGC 2207, HST data in the near-UV F336W band show that the covering factor of clouds with small optical attenuation becomes a dominant factor farther into the UV, which opens the possibility that widespread

Analytical properties of the radiance in atmospheric radiative transfer theory

International Nuclear Information System (INIS)

Otto, Sebastian

2014-01-01

It is demonstrated mathematically strictly that state density functions, as the radiance (specific intensity), exist to describe certain state properties of transported photons on microscopic and the state of the radiation field on macroscopic scale, which have independent physical meanings. Analytical properties as boundedness, continuity, differentiability and integrability of these functions to describe the photon transport are discussed. It is shown that the density functions may be derived based on the assumption of photons as real particles of non-zero and finite size, independently of usual electrodynamics, and certain historically postulated functional relationships between them were proved, that is, these functions can be derived mathematically strictly and consistently within the framework of the theory of the phenomenological radiative transfer if one takes the theory seriously by really assuming photons as particles. In this sense these functions may be treated as fundamental physical quantities within the scope of this theory, if one considers the possibility of the existence of photons. -- Highlights: • Proof of existence of the radiance within the scope of the theory of atmospheric radiative transfer. • Proof of relations between the photon number and photon energy density function and the radiance. • Strictly mathematical derivation of the analytical properties of these state density functions

Compensation for nonuniform attenuation in SPECT brain imaging

International Nuclear Information System (INIS)

Glick, S.J.; King, M.A.; Pan, T.S.; Soares, E.J.

1996-01-01

Accurate compensation for photon attenuation is needed to perform quantitative brain single-photon-emission computed tomographic (SPECT) imaging. Bellini's attenuation-compensation method has been used with a nonuniform attenuation map to account for the nonuniform attenuation properties of the head. Simulation studies using a three-dimensional (3-D) digitized anthropomorphic brain phantom were conducted to compare quantitative accuracy of reconstructions obtained with the nonuniform Bellini method to that obtained with the Chang method and to iterative reconstruction using maximum-likelihood expectation maximization (ML-EM). Using the Chang method and assuming the head to be a uniform attenuator gave reconstructions with an average bias of approximately 6-8%, whereas using the Bellini or the iterative ML-EM method with a nonuniform attenuation map gave an average bias of approximately 1%. The computation time required to implement nonuniform attenuation compensation with the Bellini algorithm is approximately equivalent to the time required to perform one iteration of ML-EM. Thus, using the Bellini method with a nonuniform attenuation map provides accurate compensation for photon attenuation within the head, and the method can be implemented in computation times suitable for routine clinical use

Evaluation of the attenuating properties of selected Greek clays for toxic inorganic elements in landfill sites.

Science.gov (United States)

Mimides, T; Perraki, T

2000-05-15

Heavy metal attenuation properties of selected clay material collected from miscellaneous Greek sites is investigated and tested in the laboratory for their suitability, either as liners in hydrologically unsafe sites or as earth covers for sanitary landfill sites. Eleven potentially hazardous elements (As, Be, Cd, Cr, Cu, Hg, Ni, Pb, Se, V, and Zn) generated by a co-disposal landfill leachate have been considered. Experimental column and static equilibrium methods for the determination of dispersion and adsorption are described. Molecular diffusion dominates the migration phenomena with a velocity range between 1.3 x 10(-5) and 3.5 x 10(-4) cm/s throughout the experiments. A simple way to evaluate dispersion coefficients from breakthrough curves gave values of between 3.90 x 10(-6) and 3.5 x 10(-4) cm2/s, with a mean value of 1.5 x 10(-5). Static adsorption equilibrium studies supported by column runs showed that Freundlich (F = kCn) isotherms express in a better way the assimilative capacities of the tested clays, with k and n values ranging from 0.06 to 1.99 and 0.55 to 1.48 correspondingly. Mathematical models involving non-linear parabolic equations are involved. The experimental data, together with finite difference techniques and some physical clay characteristics, produced trilinear textural diagrams and predictive flow transport convection-dispersion breakthrough curves for a quick estimation of the attenuating properties of clays for heavy metals.

Composites with carbon nanotube for radiation shielding application

International Nuclear Information System (INIS)

Fontainha, Críssia C.P.; Nunes, Modesto; Rosas, Víctor A.

2017-01-01

Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. New attenuators materials have been widely investigated for radiation shielding to apply in procedures as interventional radiology, Computed Tomography (CT) and nuclear medicine. In this work composites for radiation attenuation in radiodiagnostic imaging procedures made of inorganic material as filler, by a sol-gel method, in poly(vinylidene fluoride-tryfluorethylene) [P(VDF-TrFE] copolymers that are used as the polymeric matrix. Two different metal attenuators were used as fillers: zirconia stabilized by yttria (8% wt.) and bismuth oxide. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. Characterization of composites by FTIR, UV-Vis, DSC and SEM-EDS were carried out. In a previous analysis of radiation attenuation, was used an incident monochromatic X-ray beam from the RIGAKU diffractometer. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The functionalization of the carbon nanotube of multiple walls (MWNCT) in the in the P(VDF-TrFE) was evaluated. The samples present a good dispersion of the attenuator metal into presence at methacrylic acid. The cheap tube presented better dispersion in the polymer matrix than the 3100 nanotubes. Bismuth oxidation composites showed a better attenuation factor compared to Zirconia stabilized by yttria composites. (author)

Composites with carbon nanotube for radiation shielding application

Energy Technology Data Exchange (ETDEWEB)

Fontainha, Críssia C.P.; Nunes, Modesto; Rosas, Víctor A., E-mail: crissia@gmail.com [Universidade Federal de Minas Gerais (IMA/UFMG), Belo Horizonte, MG (Brazil). Dept. de Anatomia e Imagem; Santos, Adelina P.; Furtado, Clascídia A.; Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

Polymeric composites filled with attenuating metals and functionalized with carbon nanotubes (NTC) are being largely developed. New attenuators materials have been widely investigated for radiation shielding to apply in procedures as interventional radiology, Computed Tomography (CT) and nuclear medicine. In this work composites for radiation attenuation in radiodiagnostic imaging procedures made of inorganic material as filler, by a sol-gel method, in poly(vinylidene fluoride-tryfluorethylene) [P(VDF-TrFE] copolymers that are used as the polymeric matrix. Two different metal attenuators were used as fillers: zirconia stabilized by yttria (8% wt.) and bismuth oxide. Carbon nanotubes were added with different concentrations at the solution of attenuator metal under controlled magnetic stirring. Characterization of composites by FTIR, UV-Vis, DSC and SEM-EDS were carried out. In a previous analysis of radiation attenuation, was used an incident monochromatic X-ray beam from the RIGAKU diffractometer. In this setup, one reference measure is directly exposed to the x-rays being diffracted by single crystal of Si (111). Another measure the attenuated beam is performed with the composite sample under detector. The functionalization of the carbon nanotube of multiple walls (MWNCT) in the in the P(VDF-TrFE) was evaluated. The samples present a good dispersion of the attenuator metal into presence at methacrylic acid. The cheap tube presented better dispersion in the polymer matrix than the 3100 nanotubes. Bismuth oxidation composites showed a better attenuation factor compared to Zirconia stabilized by yttria composites. (author)

Rosiglitazone attenuates pulmonary fibrosis and radiation-induced intestinal damage

International Nuclear Information System (INIS)

Mangoni, M.; Gerini, C.; Sottili, M.; Cassani, S.; Stefania, G.; Biti, G.; Castiglione, F.; Vanzi, E.; Bottoncetti, A.; Pupi, A.

2011-01-01

Full text of publication follows: Purpose.-The aim of the study was to evaluate radioprotective effect of rosiglitazone (RGZ) on a murine model of late pulmonary damage and of acute intestinal damage. Methods.- Lung fibrosis: C57 mice were treated with the radiomimetic agent bleomycin, with or without rosiglitazone (5 mg/kg/day). To obtain an independent qualitative and quantitative measure for lung fibrosis we used high resolution CT, performed twice a week during the entire observation period. Hounsfield Units (HU) of section slides from the upper and lower lung region were determined. On day 31 lungs were collected for histological analysis. Acute intestinal damage: mice underwent 12 Gy total body irradiation with or without rosiglitazone. Mice were sacrificed 24 or 72 h after total body irradiation and ileum and colon were collected. Results.- Lung fibrosis: after bleomycin treatment, mice showed typical CT features of lung fibrosis, including irregular septal thickening and patchy peripheral reticular abnormalities. Accordingly, HU lung density was dramatically increased. Rosiglitazone markedly attenuated the radiological signs of fibrosis and strongly inhibited HU lung density increase (60% inhibition at the end of the observation period). Histological analysis revealed that in bleomycin-treated mice, fibrosis involved 50-55% of pulmonary parenchyma and caused an alteration of the alveolar structures in 10% of parenchyma, while in rosiglitazone-treated mice, fibrosis involved only 20-25% of pulmonary parenchyma, without alterations of the alveolar structures. Acute intestinal damage: 24 h after 12 Gy of total body irradiation intestinal mucosa showed villi shortening, mucosal thickness and crypt necrotic changes. Rosiglitazone showed a histological improvement of tissue structure, with villi and crypts normalization and oedema reduction. Conclusion.- These results demonstrate that rosiglitazone displays a protective effect on pulmonary fibrosis and radiation

Rosiglitazone attenuates pulmonary fibrosis and radiation-induced intestinal damage

Energy Technology Data Exchange (ETDEWEB)

Mangoni, M.; Gerini, C.; Sottili, M.; Cassani, S.; Stefania, G.; Biti, G. [Radiotherapy Unit, Clinical Physiopathology Department, University of Florence, Firenze (Italy); Castiglione, F. [Department of Human Pathology and Oncology, University of Florence, Firenze (Italy); Vanzi, E.; Bottoncetti, A.; Pupi, A. [Nuclear Medicine Unit, Clinical Physiopathology Department, University of Florence, Firenze (Italy)

2011-10-15

Full text of publication follows: Purpose.-The aim of the study was to evaluate radioprotective effect of rosiglitazone (RGZ) on a murine model of late pulmonary damage and of acute intestinal damage. Methods.- Lung fibrosis: C57 mice were treated with the radiomimetic agent bleomycin, with or without rosiglitazone (5 mg/kg/day). To obtain an independent qualitative and quantitative measure for lung fibrosis we used high resolution CT, performed twice a week during the entire observation period. Hounsfield Units (HU) of section slides from the upper and lower lung region were determined. On day 31 lungs were collected for histological analysis. Acute intestinal damage: mice underwent 12 Gy total body irradiation with or without rosiglitazone. Mice were sacrificed 24 or 72 h after total body irradiation and ileum and colon were collected. Results.- Lung fibrosis: after bleomycin treatment, mice showed typical CT features of lung fibrosis, including irregular septal thickening and patchy peripheral reticular abnormalities. Accordingly, HU lung density was dramatically increased. Rosiglitazone markedly attenuated the radiological signs of fibrosis and strongly inhibited HU lung density increase (60% inhibition at the end of the observation period). Histological analysis revealed that in bleomycin-treated mice, fibrosis involved 50-55% of pulmonary parenchyma and caused an alteration of the alveolar structures in 10% of parenchyma, while in rosiglitazone-treated mice, fibrosis involved only 20-25% of pulmonary parenchyma, without alterations of the alveolar structures. Acute intestinal damage: 24 h after 12 Gy of total body irradiation intestinal mucosa showed villi shortening, mucosal thickness and crypt necrotic changes. Rosiglitazone showed a histological improvement of tissue structure, with villi and crypts normalization and oedema reduction. Conclusion.- These results demonstrate that rosiglitazone displays a protective effect on pulmonary fibrosis and radiation

The optical properties of equatorial cirrus in the pilot radiation observation experiment

Energy Technology Data Exchange (ETDEWEB)

Platt, C.M.R.; Young, S.A.; Manson, P.; Patterson, G.R. [CSIRO, Victoria (Australia)] [and others

1996-04-01

The development of a sensitive filter radiometer for the Atmospheric Radiation Measurement (ARM) Program has been reported. The aim was to develop a reliable and fast instrument that could be used alongside a lidar to obtain near realtime optical properties of clouds, particularly high ice clouds, as they drifted over an ARM Cloud and Radiation Testbed (CART) site allowing calculation of the radiation divergence in the atmosphere over the site. Obtaining cloud optical properties by the lidar/radiometer, or LIRAD, method was described by Platt et al.; the latter paper also describes a year`s data on mid-latitude cirrus. The optical properties of equatorial cirrus (i.e., cirrus within a few degrees of the equator) have hardly been studied at all. The same is true of tropical cirrus, although a few observations have been reported by Davis and Platt et al.This paper describes obersvations performed on cirrus clouds, analysis methods used, and results.

Investigation of ionizing radiation shielding effectiveness of decorative building materials used in Bangladeshi dwellings

International Nuclear Information System (INIS)

Yesmin, Sabina; Sonker Barua, Bijoy; Uddin Khandaker, Mayeen; Tareque Chowdhury, Mohammed; Kamal, Masud; Rashid, M.A.; Miah, M.M.H.; Bradley, D.A.

2017-01-01

Following the rapid growing per capita income, a major portion of Bangladeshi dwellers is upgrading their non-brick houses by rod-cement-concrete materials and simultaneously curious to decorate the houses using luxurious marble stones. Present study was undertaken to investigate the gamma-ray attenuation co-efficient of decorative marble materials leading to their suitability as shielding of ionizing radiation. A number of commercial grades decorative marble stones were collected from home and abroad following their large-scale uses. A well-shielded HPGe γ-ray spectrometer combined with associated electronics was used to evaluate the mass attenuation coefficients of the studied materials for high energy photons. Some allied parameters such as half-value layer and radiation protection efficacy of the investigated marbles were calculated. The results showed that among the studied samples, the marble ‘Carrara’ imported from Italy is suitable to be used as radiation shielding material. - Highlights: • Studies of decorative building materials for shielding of ionizing radiation. • High energy photon beam were used to obtain various interaction properties. • Marble stone ‘Carrara’ from Italy shows suitability to be used as shielding material.

Photon mass attenuation coefficients of a silicon resin loaded with WO3, PbO, and Bi2O3 Micro and Nano-particles for radiation shielding

Science.gov (United States)

Verdipoor, Khatibeh; Alemi, Abdolali; Mesbahi, Asghar

2018-06-01

Novel shielding materials for photons based on silicon resin and WO3, PbO, and Bi2O3 Micro and Nano-particles were designed and their mass attenuation coefficients were calculated using Monte Carlo (MC) method. Using lattice cards in MCNPX code, micro and nanoparticles with sizes of 100 nm and 1 μm was designed inside a silicon resin matrix. Narrow beam geometry was simulated to calculate the attenuation coefficients of samples against mono-energetic beams of Co60 (1.17 and 1.33 MeV), Cs137 (663.8 KeV), and Ba133 (355.9 KeV). The shielding samples made of nanoparticles had higher mass attenuation coefficients, up to 17% relative to those made of microparticles. The superiority of nano-shields relative to micro-shields was dependent on the filler concentration and the energy of photons. PbO, and Bi2O3 nanoparticles showed higher attenuation compared to WO3 nanoparticles in studied energies. Fabrication of novel shielding materials using PbO, and Bi2O3 nanoparticles is recommended for application in radiation protection against photon beams.

Improvement of BaO:B2O3:Fly ash glasses: Radiation shielding, physical and optical properties

International Nuclear Information System (INIS)

Tuscharoen, S.; Kaewkhao, J.; Limkitjaroenporn, P.; Limsuwan, P.; Chewpraditkul, W.

2012-01-01

Highlights: ► BaO:B 2 O 3 :Fly ash glasses have been improved in radiation Shielding, physical and optical properties. ► The visible light transmission of RHA glass was better than SiO 2 . ► At all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete. -- Abstract: Rice husk ash glass (RHA-glass) of composition xBaO:(80 − x)B 2 O 3 :20RHA where x = 45, 50, 55, 60, 65 and 70 wt.% have been prepared using melt-quenching method and investigated on their optical, physical and gamma-rays shielding properties. The densities of these glass samples were increased with increasing of BaO content, due to higher molecular weight of BaO comparing with B 2 O 3 . The molar volume of these glasses was increased with increasing content of BaO; BaO acts as modifier to increase the loose packing. The visible light transmission of RHA glass was better than SiO 2 glass prepared in same formula and preparing condition. The experimental values of gamma ray shielding properties such as; mass attenuation coefficients, atomic cross sections and effective atomic numbers, were found in good agreement with the theoretical values as calculated from WinXCom. Moreover the glass system at all BaO concentrations, exhibited the better half values layer in comparison window and ordinary concrete.

Radiation protective agents possessing anti-oxidative properties

Energy Technology Data Exchange (ETDEWEB)

Anzai, Kazunori; Ueno, Emi; Yoshida, Akira; Furuse, Masako; Ikota, Nobuo [National Inst. of Radiological Sciences, Research Center for Radiation Safety, Chiba, Chiba (Japan)

2005-11-15

The purpose of studies is to see mechanisms of radiation protection of agents possessing anti-oxidative properties because the initial step resulting in radiation hazard is the formation of radicals by water radiolysis. Agents were commercially available or synthesized proxyl derivatives (spin prove agents), commercially available spin-trapping agents, edaravone and TMG (a tocopherol glycoside). Mice and cultured cells were X-irradiated by Shimadzu Pantak HF-320 or 320S. Survivals of cells were determined by colony assay and of mice, to which the agents were given intraperitoneally before or after X-irradiation, within 30 days post irradiation. Plasma and marrow concentrations of proxyls were estimated by electron spin resonance (ESR) spectrometry. Mechanisms of their radiation protective effects were shown different from agent to agent. TMG was found effective even post irradiation, which suggests a possibility for a new drug development. Some (spin trapping agents and TMG), virtually ineffective at the cell level, were found effective in the whole body, suggesting the necessity of studies on their disposition and metabolism. (S.I.)

Radiation protective agents possessing anti-oxidative properties

International Nuclear Information System (INIS)

Anzai, Kazunori; Ueno, Emi; Yoshida, Akira; Furuse, Masako; Ikota, Nobuo

2005-01-01

The purpose of studies is to see mechanisms of radiation protection of agents possessing anti-oxidative properties because the initial step resulting in radiation hazard is the formation of radicals by water radiolysis. Agents were commercially available or synthesized proxyl derivatives (spin prove agents), commercially available spin-trapping agents, edaravone and TMG (a tocopherol glycoside). Mice and cultured cells were X-irradiated by Shimadzu Pantak HF-320 or 320S. Survivals of cells were determined by colony assay and of mice, to which the agents were given intraperitoneally before or after X-irradiation, within 30 days post irradiation. Plasma and marrow concentrations of proxyls were estimated by electron spin resonance (ESR) spectrometry. Mechanisms of their radiation protective effects were shown different from agent to agent. TMG was found effective even post irradiation, which suggests a possibility for a new drug development. Some (spin trapping agents and TMG), virtually ineffective at the cell level, were found effective in the whole body, suggesting the necessity of studies on their disposition and metabolism. (S.I.)

Impacts and implementation of fuel moisture release and radiation properties in modelling of pulverized fuel combustion processes

DEFF Research Database (Denmark)

Yin, Chungen

2015-01-01

. Therefore, cares must be taken in particle radiation, especially particle radiative properties. The refined weighted-sum-of-gray-gases model (WSGGM) and conversion-dependent particle radiative property models presented in the paper are recommended for use in generic CFD modelling of PF combustion....

Radiation degradation in the mechanical properties of Polyetheretherketone–alumina composites

International Nuclear Information System (INIS)

Lawrence, Falix; Mallika, C.; Kamachi Mudali, U.; Natarajan, R.; Ponraju, D.; Seshadri, S.K.; Sampath Kumar, T.S.

2012-01-01

Polyetheretherketone (PEEK) is extensively employed in corrosive and radiation environments. To improve the radiation tolerance of PEEK in the presence of high energetic radiation, PEEK was reinforced with micron sized alumina powder (5–25% by weight) and PEEK–alumina composite sheets fabricated were irradiated to 10 MGy. Mechanical properties of the irradiated composites revealed significant reduction in the degradation of PEEK with addition of alumina as the polymer reinforced with ceramic additives is expected to increase the interface area of the constituents in the system resulting in an improvement in the performance of the reinforced material.

Interaction of ionising radiations with matter

International Nuclear Information System (INIS)

Caudrelier, Olivier

2010-01-01

In a first part, this academic course addresses the interaction of non-charged particles with matter. The author more particularly addresses the interaction of a photon plasma with matter (attenuation of electromagnetic radiations, law of exponential attenuation, attenuation half value layer), the elementary phenomena of the interaction of a photon with matter (photoelectric effect, Compton effect, Thomson-Rayleigh scattering, materialisation, photo-nuclear reaction, prevalence domains, application in medical imagery), and the interaction of fast and slow neutrons with matter (elastic and inelastic scattering, radiative and non-radiative capture). The second part addresses the interaction of charged particles with matter. The author more particularly addresses the interaction with electrons present in the medium (ionization, excitation, stop efficiency, linear energy transfer, ionization linear density), the interaction with the nucleus (Bremsstrahlung), and the case of light particles (electrons) and of heavy particles (protons, alpha, fission products)

The effects of high energy radiation on the pulping properties of Pinus radiation and Eucalyptus regnans

International Nuclear Information System (INIS)

McLaren, K.G.; Garland, C.P.; Higgins, H.G.

1976-01-01

Studies have been made of the effects of high energy radiation on the pulping behaviour of Eucalyptus regnans and Pinus radiata. Pre-irradiation of wood chips with small doses of 60 Co gamma radiation (up to about 0.2 Mrad) caused little degradation of the cellulose, and had only minor effects on the kraft pulping properties of both wood species. Pulp yield, Kappa number and strength properties of the pulps showed little change. There was also little effect on the bisulphite cooking of Pinus radiata. As the dose was increased to 1 Mrad, degradation of cellulose (as indicated by degree of polymerisation measurements) became significant, and Kraft pulp yields from both woods showed small reductions. The Kappa number and physical properties of these pulps were little affected at this dose level. A gamma radiation dose of 10 Mrad produced marked depolymerisation of the cellulose, and big reductions in kraft and neutral sulphite semi-chemical pulp yields. The kraft pulps showed a much higher lignin content. Some low dose (0.15 Mrad) irradiations on thin chips were carried out with a 1 MeV electron accelerator. In contrast to comparable gamma irradiations, this treatment produced discernible changes in kraft pulping behaviour. The pulp yield, under the same cooking conditions, appears to be slightly higher, but the Lignin content of the pulp was increased. (Author)

Radiation Improved Mechanical and Thermal Property of PP/HDPE

International Nuclear Information System (INIS)

Chaisupaditsin, M.; Thammit, C.; Techakiatkul, C.

1998-01-01

The mechanical properties, thermal properties and gel contents of PP-irradiated HDPE blends were studied. HDPE was gamma irradiated in the dose range of 10-30 kGy. The ratios of polymer blends of 30PP:70HDPE was mixed by a twin screw extruder at speed of 50 rpm. Irradiated HDPE with 30 kGy showed the highest gel contents. The blends ratio of 30PP:70HDPE (30 kGy) shows better heat resistance than the blends with non-irradiated HDPE. With increasing the radiation doses, the mechanical properties of the blends were improved

Influence of surface oxidation on the radiative properties of ZrB{sub 2}-SiC composites

Energy Technology Data Exchange (ETDEWEB)

Li, Ning, E-mail: lncaep@163.com [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (China); Xing, Pifeng; Li, Cui [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, 621900 (China); Wang, Peng [School of Material Science and Engineering, Shandong University of Technology, Zibo 255049 (China); Jin, Xinxin [College of Materials Science and Engineering, Harbin University of Science and Technology, Harbin 150040 (China); Zhang, Xinghong [Science and Technology on Advanced Composites in Special Environments Laboratory, Harbin Institute of Technology, Harbin 150001 (China)

2017-07-01

Highlights: • Surface component affected radiative properties of ZrB{sub 2}-SiC composites significantly. • Emissivity in long-wave range gradually increased with the thickness of oxide scale. • The surface temperature had a little effect on radiative properties of composites. • Influence of surface roughness on emissivity could be negligible. • Covering the surface with glass is a method for improving radiative properties. - Abstract: The spectral emissivities of ZrB{sub 2}-20 vol.% SiC composites with various surface components of ZrB{sub 2}/SiC (ZS1), silica-rich glass (ZS2) and porous zirconia (ZS3) were measured using infrared spectrometer in the wavelength range from 2.5 to 25.0 μm. The relationship between surface oxidation (associated with surface component, thickness of oxide scale, testing temperature as well as roughness) and the radiative properties of ZrB{sub 2}-SiC composites were investigated systematically. Surface component affected the radiative properties of composites significantly. The total emissivity of ZS1 varied from 0.22 to 0.81 accompanied with surface oxidation in the temperature range 300–900 °C. The emissivity of ZS2 was about 1.5 times as that of ZS3 under the same testing conditions. The oxide scale on specimen surface enhanced the radiative properties especially in terms of short-wave range, and the emissivity in the long-wave range gradually increased with the thickness of oxide scale within a certain range. The influence of testing temperature and surface roughness was also investigated. The testing temperature had a little effect on radiative properties, whereas effect of surface roughness could be negligible.

UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Directory of Open Access Journals (Sweden)

J. Para

2013-04-01

Full Text Available Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC, and optical characteristics including UV (ultraviolet radiation and PAR (photosynthetically active radiation diffuse attenuation (Kd, and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM as part of the MALINA field campaign (30 July to 27 August. Spectral absorption coefficients (aCDOM (350 nm (m−1 were significantly correlated to both diffuse attenuation coefficients (Kd in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1–C3 were identified by fluorescence excitation/emission matrix spectroscopy (EEMS and parallel factor (PARAFAC analysis. Our results showed an aquatic dissolved organic matter (DOM component (C1, probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2 in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

UV/PAR radiation and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Science.gov (United States)

Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

2013-04-01

Surface waters from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV (ultraviolet) radiation and PAR (photosynthetically active radiation) diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of both UV and PAR solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. While the Mackenzie input is the main driver of CDOM dynamics in low salinity waters, locally, primary production can create significant increases in CDOM. Extrapolating CDOM to DOC relationships, we estimate that ∼16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. The discharges of DOC and its chromophoric subset (CDOM) by the Mackenzie River during the MALINA cruise are estimated as ∼0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence excitation/emission matrix spectroscopy (EEMS) and parallel factor (PARAFAC) analysis. Our results showed an aquatic dissolved organic matter (DOM) component (C1), probably produced in the numerous lakes of the watershed, that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta Sector. This aquatic DOM could partially explain the high CDOM spectral slopes observed in the Beaufort Sea.

Toxic properties of specific radiation determinant molecules, derived from radiated species

Science.gov (United States)

Popov, Dmitri; Maliev, Vecheslav; Kedar, Prasad; Casey, Rachael; Jones, Jeffrey

Introduction: High doses of radiation induce the formation of radiation toxins in the organs of irradiated mammals. After whole body irradiation, cellular macromolecules and cell walls are damaged as a result of long-lived radiation-induced free radicals, reactive oxygen species, and fast, charged particles of radiation. High doses of radiation induce breaks in the chemical bonds of macromolecules and cross-linking reactions via chemically active processes. These processes result in the creation of novel modified macromolecules that possess specific toxic and antigenic properties defined by the type and dose of irradiation by which they are generated. Radiation toxins isolated from the lymph of irradiated animals are classified as hematotoxic, neurotoxic, and enteric non-bacterial (GI) radiation toxins, and they play an important role in the development of hematopoietic, cerebrovascular, and gastrointestinal acute radiation syndromes (ARS). Seven distinct toxins derived from post-irradiated animals have been designated as Specific Radiation Determinants (SRD): SRD-1 (neurotoxic radiation toxin generated by the cerebrovascular form of ARS), SRD-3 (enteric non-bacterial radiation toxins generated by the gastrointestinal form of ARS), and SRD-4 (hematotoxic radiation toxins generated by the hematological, bone marrow form of ARS). SRD-4 is further subdivided into four groups depending on the severity of the ARS induced: SRD-4/1, mild ARS; SRD-4/2, moderate ARS; SRD-4/3, severe ARS; and SRD-4/4, extremely severe ARS. The seventh SRD, SRD-2 is a toxic extract derived from animals suffering from a fourth form of ARS, as described in European literature and produces toxicity primarily in the autonimic nervous system. These radiation toxins have been shown to be responsible for the induction of important pathophysiological, immunological, and biochemical reactions in ARS. Materials and Methods: These studies incorporated the use of statistically significant numbers of a

Infuence of gamma radiation on the rheological and functional properties of bread wheats

International Nuclear Information System (INIS)

Paredes-Lopez, O.; Covarrubias-Alvarez, M.M.

1984-01-01

The effects of gamma irradiation on some biochemical, rheological and functional properties of bread wheats were studied. Two wheat cultivars were selected to represent medium-strong and weak dough mixing strengths. Falling number values were severely depressed at doses of 500 and 1000 krad. Rheological dough properties, as assessed with the mixograph and farinograph, were also investigated. Radiation at medium doses produced an increase in the farinograph water absorption for both wheats. Radiation decreased the amount of bound water as compared to the control sample. For the medium-strong wheat low levels of radiation produced bread with volumes and overall bread quality equal to or slightly better than those of the control flour, whereas for the weak wheat an improvement of the baking performance was obtained at all the low doses of radiation. However, the overall bread quality of both wheats was highly reduced at medium doses of radiation. (author)

Role of neurotensin in radiation-induced hypothermia in rats

International Nuclear Information System (INIS)

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

1991-01-01

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

Properties of sound attenuation around a two-dimensional underwater vehicle with a large cavitation number

International Nuclear Information System (INIS)

Ye Peng-Cheng; Pan Guang

2015-01-01

Due to the high speed of underwater vehicles, cavitation is generated inevitably along with the sound attenuation when the sound signal traverses through the cavity region around the underwater vehicle. The linear wave propagation is studied to obtain the influence of bubbly liquid on the acoustic wave propagation in the cavity region. The sound attenuation coefficient and the sound speed formula of the bubbly liquid are presented. Based on the sound attenuation coefficients with various vapor volume fractions, the attenuation of sound intensity is calculated under large cavitation number conditions. The result shows that the sound intensity attenuation is fairly small in a certain condition. Consequently, the intensity attenuation can be neglected in engineering. (paper)

Note: Attenuation motion of acoustically levitated spherical rotor

Science.gov (United States)

Lü, P.; Hong, Z. Y.; Yin, J. F.; Yan, N.; Zhai, W.; Wang, H. P.

2016-11-01

Here we observe the attenuation motion of spherical rotors levitated by near-field acoustic radiation force and analyze the factors that affect the duration time of free rotation. It is found that the rotating speed of freely rotating rotor decreases exponentially with respect to time. The time constant of exponential attenuation motion depends mainly on the levitation height, the mass of rotor, and the depth of concave ultrasound emitter. Large levitation height, large mass of rotor, and small depth of concave emitter are beneficial to increase the time constant and hence extend the duration time of free rotation.

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

International Nuclear Information System (INIS)

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

2001-01-01

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

Study of sugar cooking degree to sugar obtention using gamma attenuation

International Nuclear Information System (INIS)

Holanda Cavalcanti, J. de.

1984-01-01

The application of gamma radiation attenuation methodology in the determination of sugar cooking degree is studied. Several experiments with samples of vacuum equipment during the cooking were made, based on beam intensity variations of a radioactive source of Americium 241. One sensible difference between the sirup emergent radiation and the cooked mass was observed. (M.A.C.) [pt

Foundations of radiation physics and radiation protection. 5. ed.; Grundlagen der Strahlungsphysik und des Strahlenschutzes

Energy Technology Data Exchange (ETDEWEB)

Krieger, Hanno

2017-07-01

The following topics are dealt with: Types of radiation and radiation fields, the atomic structure, radioactive decays, decay law, natural and artificial radioactivity, interactions of ionizing photon radiation, attenuation of neutral-particle beams, interactions of neutron radiation, interactions of charged particles, ionization and energy transfer, radiation doses, radiation protection phantoms, foundations of the radiation biology of cells, effects and risks of ionizing radiation, radiation expositions of men with ionizing radiation, radiation protection law, practical radiation protection against ionizing radiations, radiation eposures in medical radiology. (HSI)

Properties of cellulose derivatives produced from radiation-Modified cellulose pulps

International Nuclear Information System (INIS)

Iller, Edward; Stupinska, Halina; Starostka, Pawel

2007-01-01

The aim of project was elaboration of radiation methods for properties modification of cellulose pulps using for derivatives production. The selected cellulose pulps were exposed to an electron beam with energy 10 MeV in a linear accelerator. After irradiation pulps underwent the structural and physico-chemical investigations. The laboratory test for manufacturing carboxymethylocellulose (CMC), cellulose carbamate (CC) and cellulose acetate (CA) with cellulose pulps irradiated dose 10 and 15 kGy have been performed. Irradiation of the pulp influenced its depolimerisation degree and resulted in the drop of viscosity of CMC. However, the expected level of cellulose activation expressed as a rise of the substitution degree or increase of the active substance content in the CMC sodium salt was not observed. In the case of cellulose esters (CC, CA) formation, the action of ionising radiation on cellulose pulps with the dose 10 and 15 kGy enables obtaiment of the average values of polimerisation degree as required for CC soluble in aqueous sodium hydroxide solution. The properties of derivatives prepared by means of radiation and classic methods were compared

Influence of gamma radiation on the immunological and immunochemical properties of cholera

International Nuclear Information System (INIS)

Nedugova, G.I.; Rubtsov, I.V.; Samojlenko, I.I.

1984-01-01

Results of studying the effect of gamma-radiation on immunochemical properties and serologic activity of unpurified cholera exotoxin are presented. It is found that in irradiated toxin preparations physico-chemical alterations take place as the dose of ionizing radiation increases, which brings about the increase in electrophoretic mobility, aggregation of protein components. It is shown that serologic activity contained in antigene toxin preparations retains within the limits of radiation doses studied

Effect of Ionizing Beta Radiation on the Mechanical Properties of Poly(ethylene under Thermal Stress

Directory of Open Access Journals (Sweden)

Bednarik Martin

2016-01-01

Full Text Available It was found in this study, that ionizing beta radiation has a positive effect on the mechanical properties of poly(ethylene. In recent years, there have been increasing requirements for quality and cost effectiveness of manufactured products in all areas of industrial production. These requirements are best met with the polymeric materials, which have many advantages in comparison to traditional materials. The main advantages of polymer materials are especially in their ease of processability, availability, and price of the raw materials. Radiation crosslinking is one of the ways to give the conventional plastics mechanical, thermal, and chemical properties of expensive and highly resistant construction polymers. Several types of ionizing radiation are used for crosslinking of polymers. Each of them has special characteristics. Electron beta and photon gamma radiation are used the most frequently. The great advantage is that the crosslinking occurs after the manufacturing process at normal temperature and pressure. The main purpose of this paper has been to determine the effect of ionizing beta radiation on the tensile modulus, strength and elongation of low and high density polyethylene (LDPE and HDPE. These properties were examined in dependence on the dosage of the ionizing beta radiation (non-irradiated samples and those irradiated by dosage 99 kGy were compared and on the test temperature. Radiation cross-linking of LDPE and HDPE results in increased tensile strength and modulus, and decreased of elongation. The measured results indicate that ionizing beta radiation treatment is effective tool for improvement of mechanical properties of LDPE and HDPE under thermal stress.

Effect of gamma radiation on properties of a composite rocket propellant

International Nuclear Information System (INIS)

Dedgaonkar, V.G.; Pol, V.G.; Navle, P.B.; Ghorpade, V.G.; Wani, V.S.

2000-01-01

Gamma radiation was employed for modifying the properties of a composite rocket propellant prepared in a standard way. It was observed that when the same gamma dose was imparted to hydroxy terminated polybutadiene (HTPB) then converted into propellant, the enhancement in the properties was much larger than the irradiated propellant samples. (author)

Effects of radiation on the structure of bothropstoxin-1

Energy Technology Data Exchange (ETDEWEB)

Spencer, P.J. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: pspencer@net.ipen.br

2000-07-01

Ionizing radiation has been widely employed to attenuate venoms and toxins, preserving and even enhancing their immunogenic properties. However, little is known about molecular changes in irradiated proteins. In this work, we compared native and irradiated bothropstoxin-1, with the aim of characterizing the structural modifications induced by radiation. Our results indicate that radiation promotes a transition from the multimeric to the monomeric state in a dose-dependent manner. Spectral and calorimetric analysis suggest that the irradiated molecules undergo oxidation and partially unfold the remaining elements being stabilized by the seven disulphide bonds. The binding pattern of monoclonal antibodies raised against irradiated bothropstoxin indicated that most of the recognized epitopes are linear present on the surface of both native and irradiated toxin. Also, irradiated toxin appears to be more immunogenic, inducing the formation of native toxin-binding antibodies. (author)

Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

Energy Technology Data Exchange (ETDEWEB)

Lee, Kyun Ho [Sejong University, Sejong (Korea, Republic of); Kim, Ki Wan [Agency for Defense Development, Daejeon (Korea, Republic of)

2014-09-15

The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem.

Inverse Estimation of Surface Radiation Properties Using Repulsive Particle Swarm Optimization Algorithm

International Nuclear Information System (INIS)

Lee, Kyun Ho; Kim, Ki Wan

2014-01-01

The heat transfer mechanism for radiation is directly related to the emission of photons and electromagnetic waves. Depending on the participation of the medium, the radiation can be classified into two forms: surface and gas radiation. In the present study, unknown radiation properties were estimated using an inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure. For efficiency, a repulsive particle swarm optimization (RPSO) algorithm, which is a relatively recent heuristic search method, was used as inverse solver. By comparing the convergence rates and accuracies with the results of a genetic algorithm (GA), the performances of the proposed RPSO algorithm as an inverse solver was verified when applied to the inverse analysis of the surface radiation problem

Experimental comparison of gamma attenuations by glasses, lead, iron and concretes

International Nuclear Information System (INIS)

Charamathieu, Andre; Papot, Lucien

1964-08-01

The authors report the experimental determination, for lead glasses of density 3.3, 4.2, 5.2 and 6.2, of thicknesses equivalent to thicknesses given for lead, iron, ordinary concrete and barite concrete for Cobalt 60 and Caesium 137 radiations. Results are presented under the form of curves. Attenuation measurements made on this opportunity and those made on various hot cells have been compared with theoretical attenuation curves produced in another CEA document [fr

High energy radiation effects on mechanical properties of butyl rubber compounds

International Nuclear Information System (INIS)

Pozenato, Cristina A.; Scagliusi, Sandra R.; Cardoso, Elisabeth C.L.; Lugao, Ademar B.

2013-01-01

The high energy radiation on butyl rubber compounds causes a number of chemical reactions that occur after initial ionization and excitation events. These reactions lead to changes in molecular mass of the polymer through scission and crosslinking of the molecules, being able to affect the physical and mechanical properties. Butyl rubber has excellent mechanical properties and oxidation resistance as well as low gas and water vapor permeability. Due to all these properties butyl rubber is widely used industrially and particularly in tires manufacturing. In accordance with various authors, the major effect of high energy, such as gamma rays in butyl rubber, is the yielding of free-radicals along with changes in mechanical properties. There were evaluated effects imparted from high energy radiation on mechanical properties of butyl rubber compounds, non-irradiated and irradiated with 25 kGy, 50 kGy, 150 kGy and 200 kGy. It was also observed a sharp reducing in stress rupture and elongation at break for doses higher than 50 kGy, pointing toward changes in polymeric chain along build-up of free radicals and consequent degradation. (author)

Application of methods of mathematical modeling for determining of radiation-protective characteristics of polystyrene-metal composite materials

International Nuclear Information System (INIS)

Klepikov, V.F.; Prokhorenko, E.M.; Lytvynenko, V.V.; Zakharchenko, A.A.; Nazhmuradov, M.A.

2016-01-01

Radiation safety features of polystyrene steel composite materials were found by means of mathematical modeling techniques. We determined the attenuation of the gamma quantum flux passing through a solid protective layer compared with those attenuation for the bulk protective layer. Change of fractional attenuation of the dose absorbed by 10 and 50 mm thick composites is calculated. Dependence between protective properties of composite and its blend composition was studied. Modifications of technical process of composite materials production were performed. Rotation speed of agitator system was found. It was defined that heating time of polystyrene steel mix is longer than heating time of polystyrene tungstic one. Degree of mix heating and integrity of thermic field on its surface was controlled with the help of IR radiometry methods.

Radiation beans characterization and implantation for study of lead equivalent individual protection device used in radiodiagnostic practices

International Nuclear Information System (INIS)

Pereira, Leslie Silva

2004-01-01

The protective shielding (IPC) must be used by occupationally exposed professionals, patients and volunteers, in order to optimize the doses who receive due to radiological practices. International and national norms establish the methodology to be adopted for determination of the IPC attenuation. In this work, the IPC had been submitted to X-rays beams with known characteristics, standardized for determination of their attenuation equivalent thickness by comparison to an experimental lead attenuation slope. This comparison technique allowed insurance estimative of the IPC attenuation equivalent thickness in mm of lead. Thus, it was possible to verify the conformity of the attenuation equivalent thickness determined experimentally and the value of the thickness indicated by the manufacturer. To carry out this work, it was necessary the implementation of experimental setups stated in the specifics norms, the study of the X-rays beams original features and the determination of combined additional filters, in order to allow the X-ray equipment used operates in compliance with Norm IEC 61331-1 IEC. The radiation quality selected is characterized by a 100 kV voltage and a 0.25 mm of copper overall filtration. The implementation of this radiation quality it was carried through of its first and second HVL (Half Value Layer). Thus, a methodology according to the international Norms has been implemented in the laboratory. The results of the present work provide suitable and useful information about radiation beams features related to the determination techniques of the attenuation properties. Once implemented the procedures for conformity evaluation of the protection devices, it will be possible to carry out specific quality control tests, which will be helpful to manufacturers, customers, as well as authorities in the radiological protection and health areas. (author)

Mechanical reliability assessment of optical fibres in Radiation environments

International Nuclear Information System (INIS)

Van Uffelen, M.

2006-01-01

After more than two decades of intensive research and even some pioneering applications in space, optical fibres are now finding their way in various radiation environments, including both fission and future fusion nuclear-power plants, and high-energy physics experiments. For example, next to distributed monitoring applications of large nuclear infrastructures, fibre-optics can also be used for data communications during maintenance operations in the reactor vessel of the future ITER (International Thermonuclear Experimental Reactor), or for plasma diagnostics applications during operation of the reactor. These maintenance and diagnostics tasks require the optical fibres to withstand extremely high doses of radiation, up to MGy dose levels and temperatures above 150 degrees Celsius. The reliability assessment of fibre-optic systems for their qualification in nuclear environments often requires to meet stringent radiation tolerance levels. The majority of (usually accelerated) radiation assessments have so far focused on optical properties, such as wavelength-dependent radiation induced attenuation and radio-luminescence. The relation of these radiation effects with the fabrication methods and other environmental parameters has been the subject of years of research. Only a few results are available on the long-term evolution of mechanical properties of irradiated optical fibres. As a first step towards understanding the long-term reliability of fibre-optic composite cables in hostile radiation environments, we therefore performed dynamic fatigue tests with different commercial-grade optical fibres, both multi-mode and single-mode types

Evaluation of rubber composites as shielding materials against ionizing radiation

International Nuclear Information System (INIS)

Atia, M.K.

2010-01-01

Styrene-butadiene rubber/lead oxide composites were prepared as γ-radiation shields.The composites were prepared with different concentration of red lead oxide (Pb 3 O 4 ) .The assessment of the linear attenuation coefficient of the SBR/lead oxide composites for γ -rays from 137 Cs 137 γ-radiation point source was studied . The factors affecting the mechanical properties and shielding capacity of the composites were also studied. These factors include the lead oxide concentration, the type of monomers added and the irradiation dose. The styrene-butadiene rubber/lead oxide composites can attain up to about 43% of the shielding capacity of pure lead. The incorporation of high concentrations of lead oxide and the effect of accumulative irradiation doses up to 3000 kGy on the physico-mechanical properties of the composites were studied . These led to hardening of the SBR rubber/lead oxide composites.

Parameterization of cirrus microphysical and radiative properties in larger-scale models

International Nuclear Information System (INIS)

Heymsfield, A.J.; Coen, J.L.

1994-01-01

This study exploits measurements in clouds sampled during several field programs to develop and validate parameterizations that represent the physical and radiative properties of convectively generated cirrus clouds in intermediate and large-scale models. The focus is on cirrus anvils because they occur frequently, cover large areas, and play a large role in the radiation budget. Preliminary work focuses on understanding the microphysical, radiative, and dynamical processes that occur in these clouds. A detailed microphysical package has been constructed that considers the growth of the following hydrometer types: water drops, needles, plates, dendrites, columns, bullet rosettes, aggregates, graupel, and hail. Particle growth processes include diffusional and accretional growth, aggregation, sedimentation, and melting. This package is being implemented in a simple dynamical model that tracks the evolution and dispersion of hydrometers in a stratiform anvil cloud. Given the momentum, vapor, and ice fluxes into the stratiform region and the temperature and humidity structure in the anvil's environment, this model will suggest anvil properties and structure

Radiation shield for nuclear reactors

International Nuclear Information System (INIS)

Weissenfluh, J.A.

1978-01-01

A shield for use with nuclear reactor systems to attenuate radiation resulting from reactor operation is described. The shield comprises a container preferably of a thin, flexible or elastic material, which may be in the form of a bag, a mattress, a toroidal segment or toroid or the like filled with radiation attenuating liuid. Means are provided in the container for filling and draining the container in place. Due to its flexibility, the shield readily conforms to irregularities in surfaces with which it may be in contact in a shielding position

The role of cloud-scale resolution on radiative properties of oceanic cumulus clouds

International Nuclear Information System (INIS)

Kassianov, Evgueni; Ackerman, Thomas; Kollias, Pavlos

2005-01-01

Both individual and combined effects of the horizontal and vertical variability of cumulus clouds on solar radiative transfer are investigated using a two-dimensional (x- and z-directions) cloud radar dataset. This high-resolution dataset of typical fair-weather marine cumulus is derived from ground-based 94GHz cloud radar observations. The domain-averaged (along x-direction) radiative properties are computed by a Monte Carlo method. It is shown that (i) different cloud-scale resolutions can be used for accurate calculations of the mean absorption, upward and downward fluxes; (ii) the resolution effects can depend strongly on the solar zenith angle; and (iii) a few cloud statistics can be successfully applied for calculating the averaged radiative properties

Physical properties and thermoluminescence of glasses designed for radiation dosimetry measurements

International Nuclear Information System (INIS)

Laopaiboon, R.; Bootjomchai, C.

2015-01-01

Highlights: • TL stability of soda-lime glass was corrected by dopants. • D LDL values indicated that the glass samples have good radiation sensitivity. • Bond compression model theory was used to confirm the results from experimental. • High elastic moduli of glass samples indicated that high stability of structure. - Abstract: Soda lime glasses doped with CeO 2 , Nd 2 O 3 and MnO 2 were prepared. Thermoluminescence (TL) properties, such as glow curves and linearity of TL response on irradiation dose were investigated. Results showed that the TL properties depended on the type and concentration of the dopants. Samples were selected to calculate energy trap depth parameters. To design materials for radiation dosimetry, physical properties, ion concentration, elastic properties and effective atomic numbers are important. Theoretical bond compression models were used to determine the elastic moduli for comparison with experimental values. Results show fair agreement between theoretical and experimental measurements. The high elastic moduli of the glass samples indicated high rigidity and stability of the glass matrix structure

UV/PAR radiations and DOM properties in surface coastal waters of the Canadian shelf of the Beaufort Sea during summer 2009

Science.gov (United States)

Para, J.; Charrière, B.; Matsuoka, A.; Miller, W. L.; Rontani, J. F.; Sempéré, R.

2012-11-01

Water masses from the Beaufort Sea in the Arctic Ocean were evaluated for dissolved organic carbon (DOC), and optical characteristics including UV and PAR diffuse attenuation (Kd), and chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) as part of the MALINA field campaign (30 July to 27 August). Even with relatively low mean daily solar radiation incident on the sea surface (0.12 ± 0.03, 8.46 ± 1.64 and 18.09 ± 4.20 kJ m-2 for UV-B (305 nm), UV-A (380 nm) and PAR, respectively), we report significant light penetration with 10% irradiance depths (Z10% (λ)) reaching 9.5 m for 340 nm (UV-A) radiation in the Eastern sector and 4.5 m in the Mackenzie River influenced area (Western sector). Spectral absorption coefficients (aCDOM (350 nm) (m-1)) were significantly correlated to both diffuse attenuation coefficients (Kd) in the UV-A and UV-B and to DOC concentrations. This indicates CDOM as the dominant attenuator of UV solar radiation and suggests its use as an optical proxy for DOC concentrations in this region. Extrapolating CDOM to DOC relationships, we estimate that ~ 16% of the DOC in the Mackenzie River does not absorb radiation at 350 nm. DOC and CDOM discharges by the Mackenzie River during the MALINA Cruise are estimated as ~ 0.22 TgC and 0.18 TgC, respectively. Three dissolved fluorescent components (C1-C3) were identified by fluorescence Excitation/Emission Matrix Spectroscopy (EEMS) and PARAFAC analysis. Our results showed an in-situ biological component (C1) that co-dominated with a terrestrial humic-like component (C2) in the Mackenzie Delta sector, whereas the protein-like (C3) component dominated in the saltiest waters of the North East sector.

Polarization Property Measurement of the Long Undulator Radiation Using Cr/C Multilayer Polarization Elements

International Nuclear Information System (INIS)

Niibe, Masahito; Mukai, Mikihito; Shoji, Yoshihiko; Kimura, Hiroaki

2004-01-01

A rotating analyzer ellipsometry (RAE) system was developed with Cr/C multilayers that function as polarization elements for photon energy range of 110 - 280 eV. Polarization properties of a planar undulator change axisymmetrically in off-axial manner, and the second harmonic is more remarkable for the change. By using the RAE system, the polarization property of the second harmonic radiation from the NewSUBARU long undulator at the energy of 180 eV was examined. The degree of linear polarization of the on-axis radiation was over 0.996. The spatial distribution of the polarization azimuth was measured and was in fair agreement with the theoretical calculation. A peculiar behavior of the polarization property near the radiation peak of the second harmonic was observed by changing the height of the undulator gap

Effect of nuclear radiation on the electrical properties of chemical double layer capacitors

International Nuclear Information System (INIS)

Laghari, J.R.; Hammoud, A.N.

1990-01-01

The effects of nuclear radiation on the electrical properties of chemical double layer capacitors are determined. The capacitors were irradiated in a 2-MW nuclear reactor to different fluence levels. The exposure rate was 2.2 x 10 10 n/cm 2 · s of thermal neutrons, 9.52 x 10 8 n/cm 2 · s of fast neutrons (> 2 MeV), and 1.47 x 10 6 rad/h of gamma radiation. The properties measured during and after irradiation included the capacitance, equivalent series resistance, and open-circuit voltage. The post-irradiation effect on the leakage current was also determined. It was found that while the capacitance increased during irradiation, the equivalent series resistance and the open-circuit voltage decreased slightly during irradiation. Changes in these properties were not permanent s was evident from post-irradiation measurements. The leakage current did not show any significant change with radiation. The results indicate that chemical double layer capacitors can be suitably used as backup power source in electronic equipment operating in a radiation environment with total fluences up to 4.05 x 10 14 n/cm 2

Quantum Radiation Properties of Dirac Particles in General Nonstationary Black Holes

Directory of Open Access Journals (Sweden)

Jia-Chen Hua

2014-01-01

Full Text Available Quantum radiation properties of Dirac particles in general nonstationary black holes in the general case are investigated by both using the method of generalized tortoise coordinate transformation and considering simultaneously the asymptotic behaviors of the first-order and second-order forms of Dirac equation near the event horizon. It is generally shown that the temperature and the shape of the event horizon of this kind of black holes depend on both the time and different angles. Further, we give a general expression of the new extra coupling effect in thermal radiation spectrum of Dirac particles which is absent from the thermal radiation spectrum of scalar particles. Also, we reveal a relationship that is ignored before between thermal radiation and nonthermal radiation in the case of scalar particles, which is that the chemical potential in thermal radiation spectrum is equal to the highest energy of the negative energy state of scalar particles in nonthermal radiation for general nonstationary black holes.

The utilize of gamma radiation on the examination of mechanical properties of polymeric materials

Directory of Open Access Journals (Sweden)

F. Greškovič

2012-04-01

Full Text Available The article deals about the application area of radiation crosslinking of plastics, which follows after the injection moulding. The main objective of the presented article is the research of influence irradiation dosage on mechanical properties of materials: PP filled by 15 % of mineral filler – talc. Mechanical properties - tensile strength and impact strength by Charpy were examined in dependence on absorbed dose of the gamma rays on various conditions and were compared with non-irradiated samples. Radiation processing involves mainly the use of either electron beams from electron accelerators or gamma radiation from Cobalt-60 sources.

Attenuation and velocity dispersion in the exploration seismic frequency band

Science.gov (United States)

Sun, Langqiu

In an anelastic medium, seismic waves are distorted by attenuation and velocity dispersion, which depend on petrophysical properties of reservoir rocks. The effective attenuation and velocity dispersion is a combination of intrinsic attenuation and apparent attenuation due to scattering, transmission response, and data acquisition system. Velocity dispersion is usually neglected in seismic data processing partly because of insufficient observations in the exploration seismic frequency band. This thesis investigates the methods of measuring velocity dispersion in the exploration seismic frequency band and interprets the velocity dispersion data in terms of petrophysical properties. Broadband, uncorrelated vibrator data are suitable for measuring velocity dispersion in the exploration seismic frequency band, and a broad bandwidth optimizes the observability of velocity dispersion. Four methods of measuring velocity dispersion in uncorrelated vibrator VSP data are investigated, which are the sliding window crosscorrelation (SWCC) method, the instantaneous phase method, the spectral decomposition method, and the cross spectrum method. Among them, the SWCC method is a new method and has satisfactory robustness, accuracy, and efficiency. Using the SWCC method, velocity dispersion is measured in the uncorrelated vibrator VSP data from three areas with different geological settings, i.e., Mallik gas hydrate zone, McArthur River uranium mines, and Outokumpu crystalline rocks. The observed velocity dispersion is fitted to a straight line with respect to log frequency for a constant (frequency-independent) Q value. This provides an alternative method for calculating Q. A constant Q value does not directly link to petrophysical properties. A modeling study is implemented for the Mallik and McArthur River data to interpret the velocity dispersion observations in terms of petrophysical properties. The detailed multi-parameter petrophysical reservoir models are built according to

Radiation protection in hospitals

International Nuclear Information System (INIS)

MOuld, R.F.

1985-01-01

A book on radiation protection in hospitals has been written to cater for readers with different backgrounds, training and needs by providing an elementary radiation physics text in Part I and an advanced, comprehensive Part II relating to specific medical applications of X-rays and of radioactivity. Part I includes information on basic radiation physics, radiation risk, radiation absorption and attenuation, radiation measurement, radiation shielding and classification of radiation workers. Part II includes information on radiation protection in external beam radiotherapy, interstitial source radiotherapy, intracavitary radiotherapy, radioactive iodine-131 radiotherapy, nuclear medicine diagnostics and diagnostic radiology. (U.K.)

Study of gamma radiation shielding properties of ZnO-TeO_2 glasses

International Nuclear Information System (INIS)

Issa, Shama A.M.; Sayyed, M.I.; Kurudirek, Murat

2017-01-01

Mass attenuation coefficient (μm), half value layer (HVL) and mean free path (MFP) for xZnO-(100-x)TeO_2, where x=10, 15, 20, 25, 30, 35 and 40 mol%, have been measured for 0.662, 1.173 and 1.33 MeV photons emitted from "1"3"7Cs and "6"0Co using a 3 x 3 inch NaI (Tl) detector. Some relevant parameters such as effective atomic numbers (Z_e_f_f) and electron densities (Nel) of glass samples have been also calculated in the photon energy range of 0.015-15 MeV. Moreover, gamma-ray energy absorption buildup factor (EABF) and exposure buildup factor (EBF) were estimated using a five-parameter Geometric Progression (GP) fitting approximation, for penetration depths up to 40 MFP and in the energy range 0.015-15 MeV. The measured mass attenuation coefficients were found to agree satisfactorily with the theoretical values obtained through WinXcom. Effective atomic numbers (Z_e_f_f) and electron densities (N_e_l) were found to be the highest for 40ZnO-60TeO_2 glass in the energy range 0.04-0.2 MeV. The 10ZnO-90TeO_2 glass sample has lower values of gamma-ray EBFs in the intermediate energy region. The reported new data on radiation shielding characteristics of zinc tellurite glasses should be beneficial from the point of proper gamma shield designs when intended to be used as radiation shields. (author)

Reflecting and Polarizing Properties of Conductive Fabrics in Ultra-High Frequency Range

Directory of Open Access Journals (Sweden)

Oleg Kiprijanovič

2015-09-01

Full Text Available The system based on ultra-wide band (UWB signals was employed for qualitative estimation of attenuating, reflecting and polarizing properties of conductive fabrics, capable to prevent local static charge accumulation. Pulsed excitation of triangle monopole antenna of 6.5 cm height by rectangular electric pulses induced radiation of UWB signals with spectral density of power having maximum in ultra-high frequency (UHF range. The same antenna was used for the radiated signal receiving. Filters and amplifiers of different passband were employed to divide UHF range into subranges of 0.3-0.55 GHz, 0.55-1 GHz, 1-2 GHz and 2-4 GHz bands. The free space method, when conductive fabric samples of 50x50 cm2 were placed between transmitting and receiving antennas, was used to imitate a practical application. Received wideband signals corresponding to the defined range were detected by unbiased detectors. The fabrics made of two types of warps, containing different threads with conductive yarns, were investigated. It was estimated attenuation and reflective properties of the fabrics when electric field is collinear or perpendicular to thread direction. In the UHF range it was revealed good reflecting properties of the fabrics containing metallic component in the threads. The system has advantages but not without a certain shortcoming. Adapting it for specific tasks should lead to more effective usage, including yet unused properties of the UWB signals.

Synchrotron radiation sources: their properties and applications for VUV and X-ray spectroscopy

International Nuclear Information System (INIS)

Koch, E.E.

1976-09-01

Synchrotron radiation from accelerators and storage rings offers far reaching possibilities for many fields of basic and applied physics. The properties of synchrotron radiation, existing and planned synchrotron radiation facilities, as well as instrumental aspects are discussed. In order to illustrate the usefulness of the synchrotron radiation sources a few highlights from atomic, molelucar, and solid state spectroscopy are presented and examples from x-ray experiments and from the field of applied physics are given. (orig.) [de

Critical analysis of soil hydraulic conductivity determination using monoenergetic gamma radiation attenuation

International Nuclear Information System (INIS)

Portezan Filho, Otavio

1997-01-01

Three soil samples of different textures: LVA (red yellow latosol), LVE (dark red latosol) and LRd (dystrophic dark red latosol) were utilized for unsaturated hydraulic conductivity K(θ) measurements. Soil bulk densities and water contents during internal water drainage were measured by monoenergetic gamma radiation attenuation, using homogeneous soil columns assembled in the laboratory. The measurements were made with a collimated gamma beam of 0.003 m in diameter using a Nal(Tl) (3'' x 3 '') detector and a 137 Cs gamma source of 74 X 10 8 Bq and 661.6 KeV. Soil columns were scanned with the gamma beam from 0.01 to 0.20 m depth, in 0.01m steps, for several soil water redistribution times. The results show a great variability of the unsaturated hydraulic conductivity relation K(θ), even though homogeneous soils were used. The variability among methods is significantly smaller in relation to variability in space. The assumption of unit hydraulic gradient during redistribution of soil water utilized in the methods of Hillel, Libardi and Sisson leads to hydraulic conductivity values that increase in depth. The exponential character of the K(θ) relationship, is responsible for the difficulty of estimating soil hydraulic conductivity, which is a consequence of small variations in the porous arrangement, even in samples supposed to be homogeneous. (author)

Enhanced replication of attenuated HSV-1 in irradiated human glioma xenografts

International Nuclear Information System (INIS)

Advani, Sunil J.; Kataoka, Yasushi; Sibley, Greg S.; Song, Paul Y.; Hallahan, Dennis E.; Roizman, Bernard; Weichselbaum, Ralph R.

1997-01-01

Purpose: Previously we had shown that combining ionizing radiation (IR) with attenuated replication competent HSV-1 (R3616) significantly increased glioma xenograft eradication compared to IR or virus alone. One hypothesis is that IR induces cell factors that contribute to augment viral replication thereby increasing the efficacy of attenuated HSV-1. The purpose of this study was to examine if IR altered viral replication of attenuated HSV-1 in glioma xenografts Material and Methods: Human U-87MG glioma cells were grown in the hindlimb of athymic mice and grown to >200 mm 3 . Tumors were infected with 2x10 7 plaque forming units (pfu) of R3616 ( γ1 34.5 - ) or R7020 (multimutated, γ1 34.5 + ) on day 0 and irradiated with 20 Gy on day 1 and 25 Gy on day 2. Tumors were harvested 3, 5, 7, and 14 days after viral injection. Tumors were homogenized and sonnicated. Serial dilutions of tumor extract were overlaid on Vero cells to determine the number of pfu. In addition, in-situ hybridization to HSV-1 DNA was performed on tumors harvested at day 7. Results: In-situ hybridization revealed larger numbers of glial cells infected with HSV along with a greater distribution in the irradiated tumors compared to non-irradiated tumors. We next quantified viral particles in infected tumors +/- IR: Conclusion: Herein we demonstrate radiation enhanced viral replication as one of the interactive effects of combining IR and attenuated HSV in treating glioma xenografts and a potential therapeutic motif in the treatment of gliomas. To reduce normal tissue toxicity of HSV in glioma therapy, viruses must be attenuated. However, attenuating the virus compromises its replication and thus its potential efficacy. Our results indicate that IR augments the amount of virus recovered from human glioma xenografts for up to 3 days post IR. The results do not appear to be related to a specific mutation in the herpes genome but rather to herpes viruses in general. Yields of R7020 were greater than R

Genetically attenuated P36p-deficient Plasmodium berghei sporozoites confer long-lasting and partial cross-species protection

NARCIS (Netherlands)

Douradinha, Bruno; van Dijk, Melissa R.; Ataide, Ricardo; van Gemert, Geert-Jan; Thompson, Joanne; Franetich, Jean-Francois; Mazier, Dominique; Luty, Adrian J. F.; Sauerwein, Robert; Janse, Chris J.; Waters, Andrew P.; Mota, Maria M.

2007-01-01

Immunisation with live, radiation-attenuated sporozoites (RAS) or genetically attenuated sporozoites (GAS) of rodent plasmodial parasites protects against subsequent challenge infections. We recently showed that immunisation with Plasinodium berghei GAS that lack the microneme protein P36p protects

Radiation damage studies on the optical and mechanical properties of plastic scintillators

International Nuclear Information System (INIS)

Mizue Hamada, Margarida; Roberto Rela, Paulo; Eduardo da Costa, Fabio; Henrique de Mesquita, Carlos

1999-01-01

This paper describes the radiation damage studies on a large volume plastic scintillator based in polystyrene doped with PPO and POPOP. The consequences on their mechanical and scintillation properties were evaluated before and after irradiation with different dose rates of 60 Co gamma radiation, in several doses. The optical results show a significant difference in the radiation susceptibility, when the plastic scintillator is irradiated at low rate (0.1 kGy/h) with that irradiated at high dose rate (85 kGy/h). The losses in the optical and mechanical properties increase as the irradiation dose is increased. The damage evaluated by the transmittance, emission intensity, pulse height and tensile strength was normalized as a damage fraction and fitted by a bi-exponential function. It was observed that the damage for irradiation is not permanent and it obeys a bi-exponential function

Effect of electromagnetic radiation on the physico-chemical properties of minerals

International Nuclear Information System (INIS)

Lopez M, A.; Delgadillo G, J. A.; Vega C, H. R.

2014-08-01

The electromagnetic radiation effect represented by gamma rays was investigated through; chemical analysis, X-ray diffraction (XRD), scanning electron microscopy (Sem) and magnetization when applied at a dose of 0.5704 Gy (0.5704 J/ kg) at a feed relation of 18.40 ± 1.13 mGy/ h., in different minerals; in order to characterize the impact of the same from 137 Cs in the physicochemical properties of these minerals. All the irradiated samples showed chemical stability at this stage undetectable other both in the XRD study and in the images analysis obtained by Sem; and at present almost the same chemical composition as the non-irradiated samples. So the same patterns of X-ray diffraction thereof, show a tendency to slightly lower the intensity of the most representative peaks of each mineral phase, which may be due to a decrease in crystallinity or preferential crystallographic orientation in crystals. In the micrographs analysis obtained by Sem on the irradiated samples, some holes (open pores) present in the particles were observed, mainly chalcopyrite and sphalerite lesser extent, seen this fact may be due to Compton Effect, in the radiation process. In relation to the magnetization property, a variation is obtained in the saturation magnetization (Ms) for the irradiated samples containing iron and more significantly in the chalcopyrite case. Therefore, with the radiation level used; slight changes occurring in the physical properties of minerals, whereas they remained stable chemically. These small changes may represent a signal that electromagnetic radiation applied at higher doses, is a viable option for improving the mineral processing. (author)

Influence of the electromagnetic parameters on the surface wave attenuation in thin absorbing layers

Science.gov (United States)

Li, Yinrui; Li, Dongmeng; Wang, Xian; Nie, Yan; Gong, Rongzhou

2018-05-01

This paper describes the relationships between the surface wave attenuation properties and the electromagnetic parameters of radar absorbing materials (RAMs). In order to conveniently obtain the attenuation constant of TM surface waves over a wide frequency range, the simplified dispersion equations in thin absorbing materials were firstly deduced. The validity of the proposed method was proved by comparing with the classical dispersion equations. Subsequently, the attenuation constants were calculated separately for the absorbing layers with hypothetical relative permittivity and permeability. It is found that the surface wave attenuation properties can be strongly tuned by the permeability of RAM. Meanwhile, the permittivity should be appropriate so as to maintain high cutoff frequency. The present work provides specific methods and designs to improve the attenuation performances of radar absorbing materials.

Attenuation of a non-parallel beam of gamma radiation by thick shielding-application to the determination of the 235U enrichment with NaI detectors

International Nuclear Information System (INIS)

Mortreau, Patricia; Berndt, Reinhard

2005-01-01

The traditional method used to determine the Uranium enrichment by nondestructive analysis is based on the 'enrichment meter principle' [1]. It involves measuring the intensity of the 186 keV net peak area of 235 U in 'quasi-infinite' samples. A prominent factor, which affects the peak intensity, is the presence of gamma absorbing material (e.g., container wall, detector cover) between the sample and the detector. Its effect is taken into consideration in a commonly called 'wall thickness' correction factor. Often calculated on the basis of approximations, its performance is adequate for small attenuation factors applicable to the case of narrow beams. However these approximations do not lead to precise results when wide non-parallel beams are attenuated through thick container walls. This paper is dedicated to the calculation by numerical integration of the geometrical correction factor (K wtc ) which describes the effective mean path length of the radiation through the absorbing layer. This factor was calculated as a function of various measurement parameters (types and dimensions of the detector, of the collimator and of the shielding) for the most commonly used collimator shapes and detectors. Both coherent scattering (Rayleigh) and incoherent scattering (Compton) are taken into account for the calculation of the radiation interaction within the detector

Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

Energy Technology Data Exchange (ETDEWEB)

Mortley, Aba [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)], E-mail: aba.mortley@rmc.ca; Bonin, H.W.; Bui, V.T. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, P.O. Box 17000, Stn Forces, Kingston, ON, K7K 7B4 (Canada)

2007-12-15

Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging {sup 13}C solid state NMR spectra imply limited sample degradation with increasing radiation.

Synthesis and properties of radiation modified thermally cured castor oil based polyurethanes

International Nuclear Information System (INIS)

Mortley, Aba; Bonin, H.W.; Bui, V.T.

2007-01-01

Thermally cured polyurethanes were prepared from castor oil and hexamethylene diisocyanate (HMDI). Due to the long aliphatic chain of the castor oil component of polyurethane, thermal curing of castor oil based polyurethane (COPU) is limited by increasing polymer viscosity. To enhance further crosslinking, COPUs were exposed to doses up to 3.0 MGy produced by the mixed ionizing radiation field of a SLOWPOKE-2 research nuclear reactor. The physico-mechanical properties of castor oil based polyurethanes (COPU), unirradiated and irradiated, were characterized by mechanical tensile tests. A four-fold increase in modulus and tensile strength values from 0.930 to 4.365 MPa and 0.149 to 0.747 MPa, respectively, suggests improved physico-mechanical properties resulting from radiation. The changing areas of the carbonyl and the NH absorbance peaks and the disappearance of the isocyanate peak in the FTIR spectra as radiation progressed, indicates increased hydrogen bonding and intermolecular crosslinking, which is in agreement with the mechanical tests. Unchanging 13 C solid state NMR spectra imply limited sample degradation with increasing radiation

APD Properties and Recovery from Radiation Damage

CERN Document Server

Baccaro, Stefania; Caruso, S; Cavallari, Francesca; Dafinei, Ioan; Diemoz, Marcella; Emeliantchik, Igor; Festinesi, Armando; Longo, Egidio; Montecchi, Marco; Organtini, Giovanni; Rosi, G

1997-01-01

Avalanche photodiodes will be used to detect scintillation light from PWO crystals in the CMS electromagnetic calorimeter. Properties of Hamamatsu APD are reported special attention has been devoted to the study of radiation hardness and room temperature annealing. We found a fast recovery with a time constant of 1.3 days a medium fast recovery with a lifetime of the order of 10 days and indication of a third component with very long time constant of the order of 300 days.

Gamma radiation effects on physical properties of parchment documents: Assessment of Dmax

International Nuclear Information System (INIS)

Nunes, Inês; Mesquita, Nuno; Cabo Verde, Sandra; João Trigo, Maria; Ferreira, Armando; Manuela Carolino, Maria; Portugal, António; Luísa Botelho, Maria

2012-01-01

Parchments are important documents that give testimony for History; therefore these materials should be respected and preserved. Considering incremental biodeterioration problems that have to be faced daily, the Archive of the University of Coimbra (AUC) is involved in different scientific projects in order to evaluate and determine new methods for document decontamination and preservation. The aim of this study was to evaluate gamma radiation effects on the colour and texture of the AUC parchment documents. The assessment of these effects was used to estimate the maximum gamma radiation dose (D max ) that could guarantee parchment documents′ decontamination treatment, without significant alteration of their physical properties. Parchment samples were exposed to gamma radiation doses ranging from 10 to 30 kGy. The texture and colour of samples were assessed before and after the irradiation procedure, using a texture analyser and an electronic colorimeter. Hardness and springiness were determined based on texture spectra. Lightness (L⁎), Chroma (C), greenness vs. redness (a*) and yellowness vs. blueness (b*) values were obtained from colorimetric measures. Results indicate no significant effects of gamma radiation on the texture and colour of parchment for the studied doses. - Highlights: ► Study on the effects of gamma radiation in parchment physical properties. ► Evaluation of the uniformity of parchment samples′ physical parameters. ► Proposal of a maximum gamma radiation dose for parchment decontamination treatment.

Segmented attenuation correction using artificial neural networks in positron tomography

International Nuclear Information System (INIS)

Yu, S.K.; Nahmias, C.

1996-01-01

The measured attenuation correction technique is widely used in cardiac positron tomographic studies. However, the success of this technique is limited because of insufficient counting statistics achievable in practical transmission scan times, and of the scattered radiation in transmission measurement which leads to an underestimation of the attenuation coefficients. In this work, a segmented attenuation correction technique has been developed that uses artificial neural networks. The technique has been validated in phantoms and verified in human studies. The results indicate that attenuation coefficients measured in the segmented transmission image are accurate and reproducible. Activity concentrations measured in the reconstructed emission image can also be recovered accurately using this new technique. The accuracy of the technique is subject independent and insensitive to scatter contamination in the transmission data. This technique has the potential of reducing the transmission scan time, and satisfactory results are obtained if the transmission data contain about 400 000 true counts per plane. It can predict accurately the value of any attenuation coefficient in the range from air to water in a transmission image with or without scatter correction. (author)

Optical radiative properties of ablating polymers exposed to high-power arc plasmas

Science.gov (United States)

Becerra, Marley; Pettersson, Jonas

2018-03-01

The radiative properties of polymers exposed to high-intensity radiation are of importance for the numerical simulation of arc-induced ablation. The paper investigates the optical properties of polymethylmethacrylate PMMA and polyamide PA6 films exposed to high-power arc plasmas, which can cause ablation of the material. A four-flux radiative approximation is first used to estimate absorption and scattering coefficients of the tested materials in the ultraviolet (UV) and in the visible (VIS) ranges from spectrophotometric measurements. The temperature-induced variation of the collimated transmissivity of the polymers is also measured from room temperature to the glass temperature of PMMA and the melting temperature of PA6. Furthermore, band-averaged absorption and scattering coefficients of non-ablating and ablating polymers are estimated from the UV to the short-wavelength infrared (SWIR), covering the range of interest for the simulation of arc-induced ablation. These estimates are obtained from collimated transmissivities measured with an additional in situ photometric system that uses a high-power, transient arc plasma to both illuminate the samples and to induce ablation. It is shown that the increase in the bulk temperature of PA6 leads to a strong reversible increase in collimated transmissivity, significantly reducing the absorption and scattering coefficients of the material. A weaker but opposite effect of temperature on the optical properties is found in PMMA. As a consequence, it is suggested that the absorption coefficient of polymers used for arc-induced ablation estimates should not be taken directly from direct collimated transmissivity measurements at room temperature. The band-averaged radiation measurements also show that the layer of products released by ablation of PMMA produces scattering radiation losses mainly in the VIS-SWIR ranges, which are only a small fraction of the total incident arc radiation. In a similar manner, the ablation layer

Attenuation of Gamma Rays by Concrete . Lead Slag Composites

International Nuclear Information System (INIS)

Ismail, I.M.; Sweelam, M.H.; Zaghloul, Y.R.; Aly, H.F.

2008-01-01

Using of wastes and industrial by-products as concrete aggregate to be used as structural and radiation shielded material has increased in the recent years. Concrete was mixed with different amounts of lead slag extracted from recycling of the spent automotive batteries as fine aggregates. The lead slag was used as partial replacement of sand in the studied composites. The concrete composites obtained were characterized in terms of density, water absorption, porosity, compressive strength and attenuation of γ- rays with different energies. The attenuation coefficient and the half value thickness of the different matrices were calculated and discussed

Influence of ionizing radiation and use of plasticizers on the mechanical properties and barrier properties of biodegradable films

International Nuclear Information System (INIS)

Ponce, Patricia; Parra, Duclerc F.; Carr, Laura G.; Sato, Juliana S.; Lugao, Ademar B.

2005-01-01

This work reports the influence of radiation and plasticizers on the barrier properties [water vapour permeability (WVP)] and mechanical properties (tensile strength and elongation) of edible films made of starch. These films were prepared with 4 g of starch/100 mL of water; 2-10 g polyethylene glycol (PEG)/100 g starch; and at natural pH. Tensile strength and percentage elongation were measured using a Mechanical Universal Testing Machine Instron 4400R and the water vapour permeability was determined according to ASTM E96-80 (ASTM, 1989). The mechanical properties of starch films are influenced by the plasticizer concentration. An increase in PEG content showed a considerable increase in elongation percentage and a decrease in the tensile strength of the films, also increase the permeability of the films in water. After irradiation, the barrier properties [water vapour permeability (WVP)] and mechanical properties (tensile strength and elongation) of the films were improved due to chemical reactions among polymer molecules. The films were irradiated at room temperature with gamma radiation. Irradiated starch cassava films with polyethylene glycol (PEG) as plasticizer have good flexibility and low water permeability, which indicate potential application as edible films (author)

The influence of radiation on bacterial cells and their proteolytic properties

International Nuclear Information System (INIS)

Szulc, M.; Stefaniakowa, A.; Stanczak, B.; Peconek, J.

1980-01-01

The suspension of bacterial cells and their spores were exposed to X rays in the environment with and without protein. The doses of radiation ranged from 1 to 100 Gy and in case of spores of B. subtilis from 50 to 1000 Gy. It was found that irradiation to Proteus vulgaris, Pseudomonas fluorescens and Ps. aeruginosa caused an inconsiderable decrease of proteolytic properties of the generation originated from irradiated bacteria. Irradiation of B. subtilis spores did not influence the proteolytic activity of bacterial cells derived from the exposed spores. The degree of wasting away of bacteria exposed to the same radiation was higher than the rate of proteolytic properties decrease. The presence of protein in the surroundings had no influence on proteolytic characteristics of new generations. (author)

Light scattering reviews 7 radiative transfer and optical properties of atmosphere and underlying surface

CERN Document Server

Kokhanovsky, Alexander A

2014-01-01

This book describes modern advances in radiative transfer and light scattering. Coverage includes fast radiative transfer techniques, use of polarization in remote sensing and recent developments in remote sensing of snow properties from space observations.

Attenuation coefficient determination of printed ABS and PLA samples in diagnostic radiology standard beams

International Nuclear Information System (INIS)

Veneziani, G.R.; Correa, E.L.; Potiens, M.P.A.; Campos, L.L.

2015-01-01

IAEA code of practice TRS-457 states that standard phantoms should offer the same primary attenuation and scatter production as relevant body section of a representative patient. Material cost, availability and dimensional stability must also be considered. The goal of this study is to determine the attenuation coefficient of printed ABS and PLA in standard X-ray beams, verifying if phantoms printed with these materials could be an easier-handle substitute for PMMA, enabling the creation of different designs in an easier and cheaper way. Results show that PMMA presents higher attenuation coefficient, followed by PLA and ABS, which means that thinner PMMA layer creates higher radiation attenuation. (author)

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

Science.gov (United States)

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

2018-01-01

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

Tylvalosin exhibits anti-inflammatory property and attenuates acute lung injury in different models possibly through suppression of NF-κB activation.

Science.gov (United States)

Zhao, Zhanzhong; Tang, Xiangfang; Zhao, Xinghui; Zhang, Minhong; Zhang, Weijian; Hou, Shaohua; Yuan, Weifeng; Zhang, Hongfu; Shi, Lijun; Jia, Hong; Liang, Lin; Lai, Zhi; Gao, Junfeng; Zhang, Keyu; Fu, Ling; Chen, Wei

2014-07-01

Tylvalosin, a new broad-spectrum, third-generation macrolides, may exert a variety of pharmacological activities. Here, we report on its anti-oxidative and anti-inflammatory activity in RAW 264.7 macrophages and mouse treated with lipopolysaccharide (LPS) as well as piglet challenged with porcine reproductive and respiratory syndrome virus (PRRSV). Tylvalosin treatment markedly decreased IL-8, IL-6, IL-1β, PGE2, TNF-α and NO levels in vitro and in vivo. LPS and PRRSV-induced reactive oxygen species (ROS) production, and the lipid peroxidation in mice lung tissues reduced after tylvalosin treatments. In mouse acute lung injury model induced by LPS, tylvalosin administration significantly attenuated tissues injury, and reduced the inflammatory cells recruitment and activation. The evaluated phospholipase A2 (PLA2) activity and the increased expressions of cPLA2-IVA, p-cPLA2-IVA and sPLA2-IVE were lowered by tylvalosin. Consistent with the mouse results, tylvalosin pretreatment attenuated piglet lung scores with improved growth performance and normal rectal temperature in piglet model induced by PRRSV. Furthermore, tylvalosin attenuated the IκBα phosphorylation and degradation, and blocked the NF-κB p65 translocation. These results indicate that in addition to its direct antimicrobial effect, tylvalosin exhibits anti-inflammatory property and attenuates acute lung injury through suppression of NF-κB activation. Copyright © 2014 Elsevier Inc. All rights reserved.

Radiation grafting processes and properties of leathers modified with butyl acrylate

International Nuclear Information System (INIS)

Pietrucha, K.

1982-01-01

Conditions for radiation induced grafting with butyl acrylate dispersed in water emulsion onto chrome-tanned pig skins have been worked out for γ-rays and electron beam irradiations. The highest yield of grafting was observed at monomer concentration approximately 25% (w/w), dose equal to 25 kGy and dose rate not exceeding 10 MGy/h. At these conditions the yield of grafting attained a value approximately 25% and content of homopolymer in the leather amounted to 6%. The efficiency of monomer to polymer conversion decreases when the concentration of monomer in emulsion and dose rate increases. Yield of homopolymer is independent of the dose rate. An explanation of the observed relations has been proposed. The physical and used properties of grafted leathers were tested. Radiation processed leathers were found superior to samples finished by traditional methods. One has to point to better tolerance against chemical cleaning and reduced water take-up without loss of high permeability of water vapour, responsible for good hygienic properties of leather products. Recommendations for industrial scale radiation grafting are given. (author)

UV ATTENUATION NEAR CORAL REEFS IN THE FLORIDA KEYS: LIGHT ABSORPTION BY CDOM AND PARTICLES

Science.gov (United States)

We have investigated the roles of chromophoric dissolved organic matter (CDOM) and suspended particles in the attenuation of UV radiation in the middle and lower regions of the Florida Keys. Extended exposure to UV radiation, along with elevated sea surface temperatures, impairs...

Infrared radiative properties of anodized aluminium

Energy Technology Data Exchange (ETDEWEB)

Sharma, V.C.; Sharma, A.

1983-10-01

Measurements of anodic film thicknesses and their total hemispherical thermal emittance for various current densities (0.55-3.85 ampere/dm/sup 2/), anodizing times (1-20 min), and oxalic acid concentrations (1-6 wt.%) show a linear relationship between the film thickness and the total hemispherical thermal emittance (epsilon). Changes in oxalic acid concentration (2-4 wt.%) have no significant effect on the film growth-rate and the rate at which epsilon increases with increasing anodizing time. Measurements of epsilon for wavelengths from 3 to 30 ..mu..m show that the film growth-rate has a marked effect on the I.R. radiative properties of aluminum.

Simultaneous bulk density and soil moisture determination by attenuation of 137 Cs and 241 Am

International Nuclear Information System (INIS)

Barros Ferraz, E.S. de.

1974-01-01

The method of simultaneous bulk density and soil moisture determination by attenuation of 241 Am and 137 Cs gamma-radiation is introduced and studied with detail. Theoretical considerations are made about the attenuation process in the absorbers, the form of solving the problem of two unknowns, the sensitivity of the method the influences of the resolution time of the electronic counting equipment, and of the Compton scattering in the sample. From the methodological point of view studies are made about the influence of the geometry, adjustment of counting system, choice of radiation sources, attenuation coefficient and the manner of obtaining reliable measurements. Data obtained are analysed, discussed and compared with those found in the literature. Finally the author presents some applications of the method, its use in soil-water movement studies, in soil profile compaction studies, and specially in swelling soils. (author)

Effect of radiation processing on nutritional, functional, sensory and antioxidant properties of red kidney beans

International Nuclear Information System (INIS)

Marathe, S.A.; Deshpande, R.; Khamesra, Arohi; Ibrahim, Geeta; Jamdar, Sahayog N.

2016-01-01

In the present study dry red kidney beans (Phaseolus vulgaris), irradiated in the dose range of 0.25–10.0 kGy were evaluated for proximate composition, functional, sensory and antioxidant properties. Radiation processing up to 10 kGy did not affect proximate composition, hydration capacity and free fatty acid value. All the sensory attributes were unaffected at 1.0 kGy dose. The dose of 10 kGy, showed lower values for odor and taste, however, they were in acceptable range. Significant improvement in textural quality and reduction in cooking time was observed at dose of 10 kGy. Antioxidant activity of radiation processed samples was also assessed after normal processing such as soaking and pressure cooking. Both phenolic content and antioxidant activity evaluated in terms of DPPH free radical scavenging assay and inhibition in lipid peroxidation using rabbit erythrocyte ghost system, were marginally improved (5–10%) at the dose of 10 kGy in dry and cooked samples. During storage of samples for six months, no significant change was observed in sensory, cooking and antioxidant properties. Thus, radiation treatment of 1 kGy can be applied to get extended shelf life of kidney beans with improved functional properties without impairing bioactivity; nutritional quality and sensory property. - Highlights: • Nutritional and sensory aspects of kidney beans are not altered up to 10 kGy dose of gamma radiation. • Radiation processing at 10 kGy improves cooking quality of kidney bean seeds. • Radiation processing at 10 kGy increases antioxidant activity of kidney bean seeds.

Concrete for γ radiation shielding

International Nuclear Information System (INIS)

Azevedo e Souza, A.C. de; Rogers, John Douglas

1980-01-01

The attenuation characteristics of γ radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe 2 O 3 pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors. (Author) [pt

Concrete for. gamma. radiation shielding

Energy Technology Data Exchange (ETDEWEB)

de Azevedo e Souza, A.C. (Rio de Janeiro Univ. (Brazil). Inst. de Quimica); Rogers, J D [Rio de Janeiro Univ. (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

1980-06-01

The attenuation characteristics of ..gamma.. radiation in concrete slabs, considering their mechanical resistence and densities were determined. One heavy concrete which was used, was prepared using as additives iron ore and Fe/sub 2/ O/sub 3/ pellets in various grain sizes. Fortran programs were used for analysing data and determining the absorption coefficients and attenuation factors.

Introduction to radiological physics and radiation dosimetry

CERN Document Server

Attix, Frank Herbert

2004-01-01

A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that have not been thoroughly analyzed in other texts, such as broad-beam attenuation and geometrics, and the reciprocity theorem

Research on radiative heat transfer in sodium combustion. Modeling, verification and development a radiative properties measuring method. Report of the JNC cooperative research scheme on the nuclear fuel cycle

International Nuclear Information System (INIS)

Li Bingxi; Kudo, Kazuhiko

2001-05-01

A quantitative evaluation of a radiative heat transfer is important in sodium combustion because a large amount of aerosol particles, which are produced as a result of the combustion, exists in a combustion region. In this study, a development of radiation model with aerosols and optical property measurement has been carried out for the purpose of evaluating radiative heat transfer based on a optical property, diameter, number density and statistical and spatial distribution of aerosol particles. In 2000 research, one dimensional analysis program of the Monte Carlo method has been developed. This program evaluates a radiative transmission intensity based on an optical property and a statistic and spatial diameter distribution of airborne particles. Using this program, an optical property can be estimated from experimental conditions (e.g. diameter distribution) and results (radiative transmission intensity). As a result of numerical analyses which evaluate an influence of a size parameter (relation between a particle diameter [D] and wavelength [λ] :=πD/λ) on the accuracy evaluation, an optical property can be estimated within 3% accuracy though an angle distribution measurement of radiative transmission intensity is necessary when the size parameter becomes large. (author)

Study of material properties important for an optical property modulation-based radiation detection method for positron emission tomography

OpenAIRE

Tao, Li; Daghighian, Henry M.; Levin, Craig S.

2017-01-01

We compare the performance of two detector materials, cadmium telluride (CdTe) and bismuth silicon oxide (BSO), for optical property modulation-based radiation detection method for positron emission tomography (PET), which is a potential new direction to dramatically improve the annihilation photon pair coincidence time resolution. We have shown that the induced current flow in the detector crystal resulting from ionizing radiation determines the strength of optical modulation signal. A large...

Properties and use of construction plastics modified by ioni-- zing radiation

International Nuclear Information System (INIS)

Pandur, Ya.

1983-01-01

The change of material structure both during irradiation of ready details and preliminary irradiation of granulate before heat treatment has been studied. The change of mechanical and thermal chracteristics of polyamides of the brand ultramide AZK and ultramide BZK, as well as of propylene of the brand pro-fax 6523 (PP) and polyethylene of the brand liten 7006 (PE), irradiated with γ-rays and electrons, depending on radiation dose absorbed, has been considered. The polymer materials considered possess the optimum physicomechanical properties at the following radiation doses absorbed (in MGy): PE and PP 0.70 and 0.15 during γ-radiation and 0.20 and 0.10 during electron radiation. As a result of irradiation mechanical characteristics of the polymers except impact strength and ultimate stress during bending are increased

The measurement of longwave radiation properties upon plastic films used in greenhouses

International Nuclear Information System (INIS)

Horiguchi, I.; Tani, H.; Sugaya, H.

1982-01-01

Due to the rising cost of heating oils in recent years, the subject of heat conservation on a greenhouse has become more important. In this aspect, the plastic films used for reducing heat losses must have low transmittance property for longwave radiation, also need to have low emissivity. The properties of plastic films which affect on the transfer of energy are important. The paper discusses the measurements of reflectance, transmittance, and emissivity of longwave radiation (thermal radiation) upon various plastic films used for crop protection in agriculture, particularly in a greenhouse. New measuring methods for reflectance and emissivity were presented, and the previous transmittance calculations (Hagiwara and Horiguchi, 1972) were improved by using newly obtained reflectance values. The transmittance values obtained from the present study are about 2-5 percent larger than the values obtained from the previous study. The reason for the discrepancy may be due to the negligence of the reflectance term in the previous calculation. (author)

Physical, chemical, and biological properties of radiocerium relevant to radiation protection guidelines

International Nuclear Information System (INIS)

Anon.

1978-01-01

Present knowledge of the relevant physical, chemical, and biological properties of radiocerium as a basis for establishing radiation protection guidelines is summarized. The first section of the report reviews the chemical and physical properties of radiocerium relative to the biological behavior of internally-deposited cerium and other lanthanides. The second section of the report gives the sources of radiocerium in the environment and the pathways to man. The third section of the report describes the metabolic fate of cerium in several mammalian species as a basis for predicting its metabolic fate in man. The fourth section of the report considers the biomedical effects of radiocerium in light of extensive animal experimentation. The last two sections of the report describe the history of radiation protection guidelines for radiocerium and summarize data required for evaluating the adequacy of current radiation protection guidelines. Each section begins with a summary of the most important findings that follow

Radiative properties of strongly magnetized plasmas

International Nuclear Information System (INIS)

Weisheit, J.C.

1993-11-01

The influence of strong magnetic fields on quantum phenomena continues to be a topic of much interest to physicists and astronomers investigating a wide array of problems - the formation of high energy-density plasmas in pulsed power experiments, the crustal structure and radiative properties of neutron stars, transport coefficients of matter irradiated by subpicosecond lasers, the spectroscopy of magnetic white dwarf stars, the quantum Hall effect, etc. The passage of time finds more questions being asked than being answered in this subject, where even the hydrogen atom open-quotes paradigmclose quotes remains a major challenge. This theoretical program consists of two distinct parts: (1) investigation into the structure and transport properties of many-electron atoms in fields B > 10 8 Gauss; and (2) extension of spectral lineshape methods for diagnosing fields in strongly magnetized plasmas. Research during the past year continued to be focused on the first topic, primarily because of the interest and skills of Dr. E.P. Lief, the postdoctoral research associate who was hired to work on the proposal

Radiation protection housing

Energy Technology Data Exchange (ETDEWEB)

Maier, A

1975-04-10

The radiation protection housing consists of a foot rim with castor swivel wheels, a tubular frame tapering off at the top, and a crown. In the upper part of the tubular frame a lead glass window is permanently installed. The sides are covered with radiation attenuating curtains of leaded rubber. The housing has the shape of a truncated pyramid which can be dismantled into its constituent parts. It is used for protection from radiation encountered in X-ray facilities in dental radiology.

Determining the radiative properties of pulverized-coal particles from experiments. Final report

Energy Technology Data Exchange (ETDEWEB)

Menguec, M.P.

1992-02-01

A comprehensive coupled experimental-theoretical study has been performed to determine the effective radiative properties of pulverized-coal/char particles. The results obtained show that the ``effective`` scattering phase function of coal particles are highly forward scattering and show less sensitivity to the size than predicted from the Lorenz-Mie theory. The main reason for this is the presence of smaller size particles associated with each larger particle. Also, the coal/char particle clouds display more side scattering than predicted for the same size range spheres, indicating the irregular shape of the particles and fragmentation. In addition to these, it was observed that in the visible wavelength range the coal absorption is not gray, and slightly vary with the wavelength. These two experimental approaches followed in this study are unique in a sense that the physics of the problem are not approximated. The properties determined include all uncertainties related to the particle shape, size distribution, inhomogeneity and spectral complex index of refraction data. In order to obtain radiative property data over a wider wavelength spectrum, additional ex-situ experiments have been carried out using a Fourier Transform Infrared (FT-IR) Spectrometer. The spectral measurements were performed over the wavelength range of 2 to 22 {mu}m. These results were interpreted to obtain the ``effective`` efficiency factors of coal particles and the corresponding refractive index values. The results clearly show that the coal/char radiative properties display significant wavelength dependency in the infrared spectrum.

Effect of ionizing radiation on properties of acrylic pressure sensitive adhesives

International Nuclear Information System (INIS)

Panta, P.P.; Zimek, Z.A.; Giuszewski, W.; Kowalewski, R.; Wojtynska, E.; Wnuk, A.

1998-01-01

Pressure-sensitive adhesives for technical application are widely produced. The biological properties of adhesives depend on the type of monomers used. The available literature data as experience of the authors of this study in the area of pressure-sensitive acrylic adhesive, polymers used in medicine, polymerisation in aqueous media, radiation sterilization, permit to make an assumption that it is possible to elaborate the technology of production of pressure-sensitive adhesives in aqueous emulsion for medical applications. Identification of phenomena influencing the adhesive properties, especially its adhesion, cohesion, tack and durability is of great importance. The control of polymer structure is performed by means of adequate selection of conditions of synthesis and parameters of radiation processing. The authors investigate the influence on the final products of such factors as the type and amount of monomers used, their mutual ratio, as well as the ratio monomers and the dose of ionising radiation. There is no available literature information concerning the investigation of resistance of acrylic emulsion adhesive to sterilisation by electron beam. It is known from unpublished research that some adhesives are resistant to radiation, while others undergo destruction. It probably depends on the composition of emulsion, specifically on the additives which modify adhesives. Simultaneous achievement of good cohesion and adhesion in the case of such types of pressure sensitive adhesives is very difficult pressure sensitive adhesives is very difficult

Ionizing radiation detector using multimode optical fibers

International Nuclear Information System (INIS)

Suter, J.J.; Poret, J.C.; Rosen, M.; Rifkind, J.M.

1993-01-01

An optical ionizing radiation detector, based on the attenuation of 850-nm light in 50/125-μm multimode fibers, is described. The detector is especially well suited for application on spacecraft because of its small design. The detection element consists of a section of coiled fibers that has been designed to strip higher-order optical modes. Cylindrical radiation shields with atomic numbers ranging from Z = 13 (aluminum too) Z = 82 (lead) were placed around the ionizing radiation detector so that the effectiveness of the detector could be measured. By exposing the shields and the detector to 1.25-MeV cobalt 60 radiation, the mass attenuation coefficients of the shields were measured. The detector is based on the phenomenon that radiation creates optical color centers in glass fibers. Electron spin resonance spectroscopy performed on the 50/125-μm fibers showed the presence of germanium oxide and phosphorus-based color centers. The intensity of these centers is directly related to the accumulated gamma radiation

Evaluation of surgical gloves for radiation protection

International Nuclear Information System (INIS)

Antolin, E.; Rot, M.J.; Ordonez, J.; Arranz, L.; Sastre, J.M.; Ferrer, N.; Andres, J.C. de

2006-01-01

Full text of publication follows: Accumulated doses in hands during interventionist cardiology and radiological procedures can reach high values, and even go beyond legal limits for exposed professionals after years of work, unless they use specific radiation protection methods. An important protection mean for hands is the use of surgical gloves that attenuate the radiation while maintaining the tactile sensitivity demanded by physicians.There is a wide variety of commercialized gloves for radiation protection, with different advantages and disadvantages for various uses. In this paper nine different models of gloves have been evaluated for testing its attenuation capacity for several voltages, the maintenance of tactile sensitivity, its resistance to elongation, and the apparition of pores after successive sterilizing processes. It is very important that they do not lose its initial characteristics after processes of sterilization in order to optimize the product effective cost. The attenuation values have been measured under the voltages of 60, 70, 80 and 90 KVp obtaining very different values at each voltage with different gloves. The values measured range between 34 % before any supplementary sterilization with one model of glove (for 90 KVp), and 57 % after four sterilization processes with another glove (for 60 KVp). Some gloves lose its attenuation capacity after successive sterilizations, having not been found an y significant relation with their composition. The tactile sensitivity, a decisive factor for its users, decreases as its attenuation capacity increases, and remains mostly constant after being sterilized. The tests performed allow to conclude a set of fi nal results that can facilitate the choice of the most suitable gloves according to the practical applications (the priorities being the radiation protection and the tactile sensitivity)

Properties of an extrapolation chamber for beta radiation dosimetry

International Nuclear Information System (INIS)

Caldas, L.V.E.

The properties of a commercial extrapolation chamber were studied, and the possibility is shown of its use in beta radiation dosimetry. The chamber calibration factors were determined for several sources ( 90 Sr, 90 Y- 204 Tl and 147 Pm) making known the dependence of its response on the energy of the incident radiation. Extrapolation curves allow to obtain independence on energy for each source. One of such curves, shown for the 90 Sr- 90 Y source at 50 cm from the detector, is obtained through the variation of the chamber window thickness and the extrapolation to the null distance (determined graphically). Different curves shown also: 1) the dependence of the calibration factor on the average energy of beta radiation; 2) the variation of ionization current with the distance between the chamber and the sources; 3) the effect of the collecting electrode area on the value of calibration factors for the different sources. (I.C.R.) [pt

Development of a human live attenuated West Nile infectious DNA vaccine: Identification of a minimal mutation set conferring the attenuation level acceptable for a human vaccine

Energy Technology Data Exchange (ETDEWEB)

Yamshchikov, Vladimir, E-mail: yaximik@gmail.com; Manuvakhova, Marina; Rodriguez, Efrain; Hébert, Charles

2017-01-15

ABSTRACT: For the development of a human West Nile (WN) infectious DNA (iDNA) vaccine, we created highly attenuated chimeric virus W1806 with the serological identity of highly virulent WN-NY99. Earlier, we attempted to utilize mutations found in the E protein of the SA14-14-2 vaccine to bring safety of W1806 to the level acceptable for human use (). Here, we analyzed effects of the SA14-14-2 changes on growth properties and neurovirulence of W1806. A set including the E138K, K279M, K439R and G447D changes was identified as the perspective subset for satisfying the target safety profile without compromising immunogenicity of the vaccine candidate. The genetic stability of the attenuated phenotype was found to be unsatisfactory being dependent on a subset of attenuating changes incorporated in W1806. Elucidation of underlying mechanisms influencing selection of pathways for restoration of the envelope protein functionality will facilitate resolution of the emerged genetic stability issue. - Highlights: •Effect of mutations in E on properties of WN1806 is determined. •A subset of attenuating mutations suitable for a human vaccine is defined. •Mechanism of attenuation is proposed and illustrated. •Underlying mechanisms of neurovirulence reversion are suggested.

Radiation hardness of WLS fibres for the ATLAS Tile Calorimeter

CERN Document Server

David, M; Maio, A

2007-01-01

In this document we present the data obtained in the irradiation in a Co-60 source of WLS fibers for the TileCal calorimeter. The optical, mechanical and radiation hardness properties of these fibers were developed in close contact with three producers: Bicron, Kuraray and Pol.Hi.Tech. The results on the degradation of the light output and attenuation length from five irradiations are presented. The fibers were irradiated with a total dose at least 3 times higher than the dose predicted for 10 years of operation of LHC at nominal luminosity.

Tailoring the structure and properties of amorphous starch blending and EB-radiation processing

International Nuclear Information System (INIS)

Khandal, D.; Bliard, C.; Coqueret, X.; Mikus, P.Y.; Dole, P.; Baumberger, S.

2011-01-01

Complete text of publication follows. Starch can be used alone and in combination with other compounds to make biodegradable articles from renewable resources. Lignins and their derivatives are good candidates for limiting the water sensitivity of starch-based materials, but they exhibit poor compatibility in blends with polysaccharides. Electron beam (EB) processing is proposed as an efficient method for inducing covalent linkages between the two constituents. Compared to unirradiated starting materials, the surface and bulk properties of EB-irradiated starch - lignin blends submitted to EB irradiation showed an interesting reduction in hydrophilicity. Radiation induced grafting of lignin models onto starch was shown to impede long-term retrogradation, with limited loss of mechanical properties. The reactivity under radiation of model blends was examined by several analytical methods. Maldi-T of mass spectrometry allowed us to propose reasonable free radical mechanisms that account for the grafting of various benzyl and cinnamyl alcohols onto maltodextrins. The presence of cinnamyl derivatives was found not only to limit degradation, but also modify the properties of the formulations (improved hydrophobicity, mechanical properties). Size exclusion chromatography and gel fraction measurements confirmed unambiguously the attachment of UV-absorbing chromophores onto the maltodextrin main chain. The combination of the obtained results demonstrates the possibility of altering in a favourable way the tensile properties of plasticized starch by applying high energy radiation to properly formulated blends including aromatic compounds like cinnamyl alcohol.

Effect of radiation on disinfection and mechanical properties of Korean traditional paper, Hanji

International Nuclear Information System (INIS)

Choi, Jong-il; Chung, Yong Jae; Kang, Dai Ill; Lee, Kyu Shik; Lee, Ju-Woon

2012-01-01

Fumigants, including methyl bromide and ethylene oxide, are generally used for the preservation of the Korean cultural heritage, especially paper products like letters and books. However, the use of fumigants is banned because of their harmful effects on humans and the environment. Gamma irradiation is being considered as an alternative for the sterilization of insects and fungi in organic products. Therefore, the purpose of this study was to investigate the sterilization effects of radiation and its effect on the mechanical properties of the Korean traditional paper—Hanji. Treatment doses of 9 kGy and 8 kGy of gamma irradiation inactivated 5 log units of Aspergillus niger and Bacillus cereus spores inoculated on Hanji, respectively. The gamma irradiations up to an absorbed dose of 50 kGy resulted in no significant changes in the tensile strength, bursting strength, and appearance of Hanji. These results confirmed that radiation treatment disinfects the Korean traditional paper efficiently without changing its properties and that this treatment could be used to prevent the damage of Korean ancient archives by molds and fungi. - Highlights: ► Radiation sensitivity of mold was tested on Korean traditional paper, Hanji. ► Mechanical properties of Hanji were measured to investigate the effect of irradiation. ► This result is useful to conserve the Korean cultural heritages made by Hanji with the radiation technology.

Influence of gamma radiation on the immunobiological and immunochemical properties of cholera exotoxin

International Nuclear Information System (INIS)

Nedugova, G.I.; Rubtsov, I.V.; Samojlenko, I.I.

1984-01-01

Native cholera exotoxin (abacterial centrifugalized deposit) has been irradiated using gamma-installations with a 60 Co source. A high inactivating effect of gamma-radiation on native cholera exotoxin is established: with the increase of radiation dose cholerogenity decreased for certain (at the dose 50 kGy) a complete inactivation of all studied series of liquid filtrate-toxin took place), activity of permeability factor and toxicity for mice decreased. A higher radiostability of dry toxin preparations as compared with the liquid ones is detected. Sterilization effect of radiation is achieved at the dose 20 kGy for liquid preparations and at the dose of 30 kGy for dry ones. When preserving the irradiated preparations of raw toxin in different temperature regimes for 6 months to 1.5 year (observation time) toxic properties are not restored, immunogenous properties do not change

Effects of methods of attenuation correction on source parameter determination

Science.gov (United States)

Sonley, Eleanor; Abercrombie, Rachel E.

We quantify the effects of using different approaches to model individual earthquake spectra. Applying different approaches can introduce significant variability in the calculated source parameters, even when applied to the same data. To compare large and small earthquake source parameters, the results of multiple studies need to be combined to extend the magnitude range, but the variability introduced by the different approaches hampers the outcome. When studies are combined, there is large uncertainty and large scatter and some systematic differences have been neglected. We model individual earthquake spectra from repeating earthquakes (M˜2) at Parkfield, CA, recorded by a borehole network. We focus on the effects of trade-offs between attenuation (Q) and corner frequency in spectral fitting and the effect of the model shape at the corner frequency on radiated energy. The trade-off between attenuation and corner frequency can increase radiated energy by up to 400% and seismic moment by up to 100%.

Neutrino and dark radiation properties in light of recent CMB observations

Science.gov (United States)

Archidiacono, Maria; Giusarma, Elena; Melchiorri, Alessandro; Mena, Olga

2013-05-01

Recent cosmic microwave background measurements at high multipoles from the South Pole Telescope and from the Atacama Cosmology Telescope seem to disagree in their conclusions for the neutrino and dark radiation properties. In this paper we set new bounds on the dark radiation and neutrino properties in different cosmological scenarios combining the ACT and SPT data with the nine-year data release of the Wilkinson Microwave Anisotropy Probe (WMAP-9), baryon acoustic oscillation data, Hubble Telescope measurements of the Hubble constant, and supernovae Ia luminosity distance data. In the standard three massive neutrino case, the two high multipole probes give similar results if baryon acoustic oscillation data are removed from the analyses and Hubble Telescope measurements are also exploited. A similar result is obtained within a standard cosmology with Neff massless neutrinos, although in this case the agreement between these two measurements is also improved when considering simultaneously baryon acoustic oscillation data and Hubble Space Telescope measurements. In the Neff massive neutrino case the two high multipole probes give very different results regardless of the external data sets used in the combined analyses. When considering extended cosmological scenarios with a dark energy equation of state or with a running of the scalar spectral index, the evidence for neutrino masses found for the South Pole Telescope in the three neutrino scenario disappears for all the data combinations explored here. Again, adding Hubble Telescope data seems to improve the agreement between the two high multipole cosmic microwave background measurements considered here. In the case in which a dark radiation background with unknown clustering properties is also considered, SPT data seem to exclude the standard value for the dark radiation viscosity cvis2=1/3 at the 2σ C.L., finding evidence for massive neutrinos only when combining SPT data with baryon acoustic oscillation

Attenuation Drift in the Micro-Computed Tomography System at LLNL

Energy Technology Data Exchange (ETDEWEB)

Dooraghi, Alex A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, William [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Seetho, Isaac [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Kallman, Jeff [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lennox, Kristin [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Glascoe, Lee [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-01-12

The maximum allowable level of drift in the linear attenuation coefficients (μ) for a Lawrence Livermore National Laboratory (LLNL) micro-computed tomography (MCT) system was determined to be 0.1%. After ~100 scans were acquired during the period of November 2014 to March 2015, the drift in μ for a set of six reference materials reached or exceeded 0.1%. Two strategies have been identified to account for or correct the drift. First, normalizing the 160 kV and 100 kV μ data by the μ of water at the corresponding energy, in contrast to conducting normalization at the 160 kV energy only, significantly compensates for measurement drift. Even after the modified normalization, μ of polytetrafluoroethylene (PTFE) increases linearly with scan number at an average rate of 0.00147% per scan. This is consistent with PTFE radiation damage documented in the literature. The second strategy suggested is the replacement of the PTFE reference with fluorinated ethylene propylene (FEP), which has the same effective atomic number (Ze) and electron density (ρe) as PTFE, but is 10 times more radiation resistant. This is important as effective atomic number and electron density are key parameters in analysis. The presence of a material with properties such as PTFE, when taken together with the remaining references, allows for a broad range of the (Ze, ρe) feature space to be used in analysis. While FEP is documented as 10 times more radiation resistant, testing will be necessary to assess how often, if necessary, FEP will need to be replaced. As radiation damage to references has been observed, it will be necessary to monitor all reference materials for radiation damage to ensure consistent x-ray characteristics of the references.

Calculation of radiation attenuation coefficients, effective atomic numbers and electron densities for some building materials

International Nuclear Information System (INIS)

Damla, N.; Baltas, H.; Celik, A.; Kiris, E.; Cevik, U.

2008-01-01

Some building materials, regularly used in Turkey, such as sand, cement, gas concrete (lightweight, aerated concrete), tile and brick, have been investigated in terms of mass attenuation coefficient, effective atomic, numbers (Z eff ), effective electron densities (N e ) and photon interaction cross section (σ a ) at 14 different energies from 81- to 1332-keV gamma-ray energies. The gamma rays were detected by using gamma-ray spectroscopy, a High Purity Germanium (HPGe) detector. The elemental compositions of samples were analysed using an energy dispersive X-ray fluorescence spectrometer. Mass attenuation coefficients of these samples have been compared with tabulations based upon the results of WinXcom. The theoretical mass attenuation coefficients were estimated using the mixture rule and the experimental values of investigated parameters were compared with the calculated values. The agreement of measured values of mass attenuation coefficient, effective atomic numbers, effective electron densities and photon interaction cross section with the theory has been found to be quite satisfactory. (authors)

Formation and properties of radiation-induced defects and radiolysis products in lithium orthosilicate

Energy Technology Data Exchange (ETDEWEB)

Tiliks, J.E.; Kizane, G.K.; Supe, A.A.; Abramenkovs, A.A.; Tiliks, J.J. (Latvian Univ., Riga (Latvia)); Vasiljev, V.G. (Acad. A.A. Bochvar Inst. of Inorganic Materials, Moscow (USSR))

1991-12-01

Formation and properties of radiation-induced defects and radiolysis products in polycrystalline powders and ceramic pellets of Li{sub 4}SiO{sub 4} were studied under the effect of various types of ionizing irradiation ({gamma} quants, accelerated electrons, reactor irradiation), humidity, temperature, impurities in the samples, etc. The content of radiation defects and radiolysis products poorly depends on irradiation type, dose rate, admixture elements. The concentration of defects highly depends on the temperature of irradiation, humidity, granural size. Empirical dependence of radiolysis degree {alpha} on the dose was found: {alpha}=5x10{sup -2}xD{sup 0.5} for {gamma} and electron irradiation (T{sub rad}=300-350 K) and {alpha}=5x10{sup -3}xD{sup 0.5} for reactor radiation (T{sub rad}=700-800 K); {alpha} - matrix dissociation degree (in %); D - dose (in MGy). Colloidal lithium and silicon, lithium and silicon oxides, and O{sub 2} are the final products of radiolysis. Radiation-induced defects change tritium thermo-extraction parameters, deteriorate mechanical, thermo-physical and electric properties of ceramics. (orig.).

SEISMIC ATTENUATION FOR RESERVOIR CHARACTERIZATION

Energy Technology Data Exchange (ETDEWEB)

Joel Walls; M.T. Taner; Naum Derzhi; Gary Mavko; Jack Dvorkin

2003-12-01

We have developed and tested technology for a new type of direct hydrocarbon detection. The method uses inelastic rock properties to greatly enhance the sensitivity of surface seismic methods to the presence of oil and gas saturation. These methods include use of energy absorption, dispersion, and attenuation (Q) along with traditional seismic attributes like velocity, impedance, and AVO. Our approach is to combine three elements: (1) a synthesis of the latest rock physics understanding of how rock inelasticity is related to rock type, pore fluid types, and pore microstructure, (2) synthetic seismic modeling that will help identify the relative contributions of scattering and intrinsic inelasticity to apparent Q attributes, and (3) robust algorithms that extract relative wave attenuation attributes from seismic data. This project provides: (1) Additional petrophysical insight from acquired data; (2) Increased understanding of rock and fluid properties; (3) New techniques to measure reservoir properties that are not currently available; and (4) Provide tools to more accurately describe the reservoir and predict oil location and volumes. These methodologies will improve the industry's ability to predict and quantify oil and gas saturation distribution, and to apply this information through geologic models to enhance reservoir simulation. We have applied for two separate patents relating to work that was completed as part of this project.

Effect of forming temperature conditions on the properties of radiation laced polyethylene films

Energy Technology Data Exchange (ETDEWEB)

Trizno, M S; Gasparyan, K A; Arutyunyan, G V; Borovko, V N

1978-11-01

The effect of radiation lace on the thermomechanical properties of polyethylene films depending on the radiation dose and temperature conditions of their formation was studied. The samples were produced at 160 deg under the pressure of 150 kN/m/sup 2/ with the following cooling in two temperature conditions: 1) cooling of the sample just after pressing in the icy water, and 2) slow cooling of the sample in a press. Films obtained using above conditions were subjected to the radiation lace in the argon medium using ..gamma..-radiation of /sup 60/Co at the exposure dose of 0.8x10/sup 6/ rad/hr. The total radiation dose was from 30 to 200 Mrad. It is shown that the films, obtained under the first cooling conditions have a lower degree of crystallinity. Investigations of gel-fraction content, density, elastic modulus, deformability, modulus of high elasticity, breaking stress, and relative elongation for rupture depending on radiation doze and the degree of crystallinity have shown that minimum degree of crystallinity of initial films provided most uniform adn compact net structure in the laced polyethylene(LP). In this case the material working capacity increases at high temperatures. In order to improve the mechanical properties of LP when exploiting it in the amorphous crystalline state it is recommended to irradiate material with maximum degree of crystallinity.

Study of effect of gamma radiation on molecular weight and mechanical properties of PHB and PHNV

International Nuclear Information System (INIS)

Fechine, Guilhermino J.M.; Terence, Mauro C.; Rabello, M.S.; Willen, Renate M.R.

2011-01-01

The effect of gamma radiation on molecular weight and mechanical properties (tensile and flexural) of PHB and PHBV samples was investigated. The values of stress and strain at the break point for both mechanical properties indicated that scission molecular reactions were predominant in PHB and PHBV samples submitted to gamma radiation. These results were confirmed by Size Exclusion Chromatography (SEC) analysis. (author)

Simultaneous determination of soil density and moisture by gamma ray attenuation from Cs137 and Am241

International Nuclear Information System (INIS)

Barros Ferraz, E.S. de.

1974-09-01

The method of simultaneous bulk density and soil moisture determination by attenuation of 241 Am and 137 Cs gamma-radiation is introduced and studied with details. Theoretical considerations are made about the attenuation process in the absorbers, the form of solving the problem of two unknowns; the sensitivity of the method; the influences of the resolution time of the electronic counting equipment, and of the compton scattering in the sample. From the methodological point of view studies are made about the influence of the geometry, adjustment of counting system, choice of radiation sources, attenuation coeficients and the manner of obtaining reliable measurements. It is also presented some applications of the method, its use in soil-water movement studies, in soil profile compaction studies, and specially in swelling soils

Radiative properties of clouds

International Nuclear Information System (INIS)

Twomey, S.

1993-01-01

The climatic effects of condensation nuclei in the formation of cloud droplets and the subsequent role of the cloud droplets as contributors to the planetary short-wave albedo is emphasized. Microphysical properties of clouds, which can be greatly modified by the degree of mixing with cloud-free air from outside, are discussed. The effect of clouds on visible radiation is assessed through multiple scattering of the radiation. Cloudwater or ice absorbs more with increasing wavelength in the near-infrared region, with water vapor providing the stronger absorption over narrower wavelength bands. Cloud thermal infrared absorption can be solely related to liquid water content at least for shallow clouds and clouds in the early development state. Three-dimensional general circulation models have been used to study the climatic effect of clouds. It was found for such studies (which did not consider variations in cloud albedo) that the cooling effects due to the increase in planetary short-wave albedo from clouds were offset by heating effects due to thermal infrared absorption by the cloud. Two permanent direct effects of increased pollution are discussed in this chapter: (a) an increase of absorption in the visible and near infrared because of increased amounts of elemental carbon, which gives rise to a warming effect climatically, and (b) an increased optical thickness of clouds due to increasing cloud droplet number concentration caused by increasing cloud condensation nuclei number concentration, which gives rise to a cooling effect climatically. An increase in cloud albedo from 0.7 to 0.87 produces an appreciable climatic perturbation of cooling up to 2.5 K at the ground, using a hemispheric general circulation model. Effects of pollution on cloud thermal infrared absorption are negligible

Radiative properties tailoring of grating by comb-drive microactuator

International Nuclear Information System (INIS)

Jiao, Y.; Liu, L.H.; Liu, L.J.; Hsu, P.-F.

2014-01-01

Micro-scale grating structures are widely researched in recent years. Although micro-scale fabrication technology is highly advanced today, with grating aspect ratio greater than 25:1 being achievable some fabrication requirements, such as fine groove processing, are still challenging. Comb-drive microactuator is proposed in this paper to be utilized on simple binary grating structures for tailoring or modulating spectral radiation properties by active adjustment. The rigorous coupled-wave analysis (RCWA) is used to calculate the absorptance of proposed structures and to investigate the impacts brought by the geometry and displacement of comb-drive microactuator. The results show that the utilization of comb-drive microactuator on grating improves the absorptance of simple binary grating while avoiding the difficulty fine groove processing. Spectral radiation property tailoring after gratings are fabricated becomes possible with the comb-drive microactuator structure. - Highlights: • A microscale grating structure with comb-driven microactuator is proposed. • The movement of microactuator changes peak absorptance resonance wavelength. • Geometric and displacement effects of comb finger on absorptance are investigated. • Both RCWA and LC circuit models are developed to predict the resonance wavelength. • Resonance frequency equations of LC circuits allow quick design analysis

Ionizing radiation changes the electronic properties of melanin and enhances the growth of melanized fungi.

Science.gov (United States)

Dadachova, Ekaterina; Bryan, Ruth A; Huang, Xianchun; Moadel, Tiffany; Schweitzer, Andrew D; Aisen, Philip; Nosanchuk, Joshua D; Casadevall, Arturo

2007-05-23

Melanin pigments are ubiquitous in nature. Melanized microorganisms are often the dominating species in certain extreme environments, such as soils contaminated with radionuclides, suggesting that the presence of melanin is beneficial in their life cycle. We hypothesized that ionizing radiation could change the electronic properties of melanin and might enhance the growth of melanized microorganisms. Ionizing irradiation changed the electron spin resonance (ESR) signal of melanin, consistent with changes in electronic structure. Irradiated melanin manifested a 4-fold increase in its capacity to reduce NADH relative to non-irradiated melanin. HPLC analysis of melanin from fungi grown on different substrates revealed chemical complexity, dependence of melanin composition on the growth substrate and possible influence of melanin composition on its interaction with ionizing radiation. XTT/MTT assays showed increased metabolic activity of melanized C. neoformans cells relative to non-melanized cells, and exposure to ionizing radiation enhanced the electron-transfer properties of melanin in melanized cells. Melanized Wangiella dermatitidis and Cryptococcus neoformans cells exposed to ionizing radiation approximately 500 times higher than background grew significantly faster as indicated by higher CFUs, more dry weight biomass and 3-fold greater incorporation of (14)C-acetate than non-irradiated melanized cells or irradiated albino mutants. In addition, radiation enhanced the growth of melanized Cladosporium sphaerospermum cells under limited nutrients conditions. Exposure of melanin to ionizing radiation, and possibly other forms of electromagnetic radiation, changes its electronic properties. Melanized fungal cells manifested increased growth relative to non-melanized cells after exposure to ionizing radiation, raising intriguing questions about a potential role for melanin in energy capture and utilization.

Reduction of the scattered radiation during X-ray examination with screen-film systems

Energy Technology Data Exchange (ETDEWEB)

Vasiliev, V N; Stavitsky, R V [Moscow Research Inst. for Roentgenology and Radiology, Moscow (Russian Federation); Oshomkov, Yu V [Mosroentgen, Moscow Region (Russian Federation)

1993-01-01

In diagnostic radiography, during X-ray examination, photons scattered in the patient's body are detected by the intensifying screen and decrease the image contrast. A conventional way to avoid this image degradation is to attenuate the scattered radiation by an antiscatter grid placed between the patient's body and the screen. A grid selectivity effect originates from the greater attenuation of scattered as opposed to primary radiation. Previous authors calculated the primary and scattered radiation transmission factor of photons with initial energy 30-120 keV for a number of typical grids. The primary radiation transmission factor varied from 0.34 to 0.67 and the secondary radiation factor was equal from 0.03 to 0.13. This effect results in a contrast improvement from 2 to 6, but the patient exposure increases up to a factor of 10. In this work we studied the possibility of improving the image contrast by attenuating the scattered radiation by a secondary filter placed between the patient's body and the screen and made of an appropriate material. A selectivity effect due to the secondary filter arises from two circumstances. First, tilting incidence of the scattered radiation results in the path inside the filter being greater than the primary one. Second, the average energy of the scattered radiation is less than the primary and, hence, the attenuation coefficient is greater. (author).

Effect of 60Co-gamma radiation on the binding properties in furs

International Nuclear Information System (INIS)

Raina, R.K.

1992-01-01

New Zealand white rabbit pelts were pickled by the usual procedure and were tanned with basic aluminium sulphate, basic chromium sulphate and their combinations. Tanned furs were irradiated with 60 Co-gamma radiations in the dose range of 5.0-114.0 kGy. The effect of radiation on the binding properties of various added substances like mineral tannins, fats, moisture and shrinkage temperature has been assessed by their comparison with the control samples. The results of these investigations show that radiation on furs causes detannage, increases the moisture and bound fat content and decreases the shrinkage temperature of the furs. (author)

Effect of active-region “volume” on the radiative properties of laser heterostructures with radiation output through the substrate

Energy Technology Data Exchange (ETDEWEB)

Nekorkin, S. M.; Zvonkov, B. N.; Baidus, N. V.; Dikareva, N. V., E-mail: dnat@ro.ru; Vikhrova, O. V. [Nizhny Novgorod State University, Physicotechnical Research Institute (Russian Federation); Afonenko, A. A.; Ushakov, D. V. [Belarussian State University (Belarus)

2017-01-15

The radiative properties of InGaAs/GaAs/InGaP laser structures with radiation output through the substrate depending on the number of quantum wells in the active region and laser diodes on their basis are investigated. It is established that the presence of six–eight quantum wells in the active region is optimum from the viewpoint of observable values of the threshold current and the output optical power of lasers.

WE-D-210-04: Radiation-Induced Polymerization of Ultrasound Contrast Agents in View of Non-Invasive Dosimetry in External Beam Radiation Therapy

Energy Technology Data Exchange (ETDEWEB)

Callens, M; Verboven, E; Van Den Abeele, K [Department of Physics, Wave Propagation and Signal Processing, KU Leuven KULAK, Kortrijk (Belgium); D’Agostino, E [DoseVue NV, Hasselt (Belgium); Pfeiffer, H [Department of Materials Engineering, KU Leuven, Leuven (Belgium); D’hooge, J [Department of Cardiovascular Sciences, Bio-Medical Science Group, KU Leuven, Leuven (Belgium)

2015-06-15

Purpose: Ultrasound contrast agents (UCA’s) based on gas-filled microbubbles encapsulated by an amphiphilic shell are well established as safe and effective echo-enhancers in diagnostic imaging. In view of an alternative application of UCA’s, we investigated the use of targeted microbubbles as radiation sensors for external beam radiation therapy. As radiation induces permanent changes in the microbubble’s physico-chemical properties, a robust measure of these changes can provide a direct or indirect estimate of the applied radiation dose. For instance, by analyzing the ultrasonic dispersion characteristics of microbubble distributions before and after radiation treatment, an estimate of the radiation dose at the location of the irradiated volume can be made. To increase the radiation sensitivity of microbubbles, polymerizable diacetylene molecules can be incorporated into the shell. This study focuses on characterizing the acoustic response and quantifying the chemical modifications as a function of radiation dose. Methods: Lipid/diacetylene microbubbles were irradiated with a 6 MV photon beam using dose levels in the range of 0–150 Gy. The acoustic response of the microbubbles was monitored by ultrasonic through-transmission measurements in the range of 500 kHz to 20 MHz, thereby providing the dispersion relations of the phase velocity, attenuation and nonlinear coefficient. In addition, the radiation-induced chemical modifications were quantified using UV-VIS spectroscopy. Results: UV-VIS spectroscopy measurements indicate that ionizing radiation induces the polymerization of diacetylenes incorporated in the microbubble shell. The polymer yield strongly depends on the shell composition and the radiation-dose. The acoustic response is inherently related to the visco-elastic properties of the shell and is strongly influenced by the shell composition and the physico-chemical changes in the environment. Conclusion: Diacetylene-containing microbubbles are

Glasses impregnated with lead for radiation shielding

International Nuclear Information System (INIS)

Abd El Monem, A.M.; Kansouh, W.A.; Megahid, R.M.; Ismail, A.L.; Awad, E.M.

2005-01-01

The attenuation properties of glasses with different concentration of lead have been investigated for the attenuation of gamma-rays from cesium-137 and for total gamma rays using a beam of neutrons and gamma rays emitted from californium-252 source. Measurements have been performed using a gamma-ray spectrometer with Nal(T1) detector for gamma-rays emitted from 137 Cs and a neutron/gamma spectrometer with stilbene scintillator for measurement of total gamma-rays from 252 Cf neutron source. The latter applied the pulse shape discrimination technique to distinguish between recoil proton and recoil electron pulses. The obtained results given the form displayed pulse height spectra and attenuation relations which were used to derive the linear attenuation coefficient (μ), and the mass attenuation coefficient (mu/p) of the investigated glasses. In addition, calculations were performed to determine the attenuation properties of glass shields under investigation using XCOM code given by the others. A comparison of the shielding properties of these glasses with some standard shielding materials indicated that, the investigated glasses process the shielding advantages required for different nuclear technology applications

Beam Attenuators and the Risk of Unrecognized Large-Fraction Irradiation of Critical Tissues

International Nuclear Information System (INIS)

Luka, S.; Marks, J.E.

2015-01-01

The use of radiation beam attenuators led to radiation injury of the spinal cord in one patient and of the peripheral nerve in another due to unsuspected large-fraction irradiation. The anatomic distribution of radiation dose was reconstructed in the sagittal plane for the patient who developed radiation myelopathy and in the axial plane for the patient who developed peripheral neuropathy. The actual dose delivered to the injured structure in each patient was taken from the dose distribution and recorded along with the time, number of fractions, and dose per fraction. The patient who developed radiation myelopathy received a total of 46.5 Gy in twenty-three 2.1 Gy fractions in 31 days to the upper cervical spinal cord where the thickness of the neck was less than the central axis thickness due to cervical lordosis and absence of a posterior compensating filter. The patient who developed peripheral neuropathy received 55 Gy in twenty-five 2.2 Gy fractions in 50 days to the femoral nerve using bolus over the groins and an anterior one-half value layer Cerrobend pelvic block to bias the dose anteriorly. Compensating filters and other beam attenuators should be used with caution because they may result in unsuspected large-fraction irradiation and total doses of radiation that exceed the tolerance of critical structures.

Beam Attenuators and the Risk of Unrecognized Large-Fraction Irradiation of Critical Tissues

Energy Technology Data Exchange (ETDEWEB)

Luka, S.; Marks, J.E.

2015-01-15

The use of radiation beam attenuators led to radiation injury of the spinal cord in one patient and of the peripheral nerve in another due to unsuspected large-fraction irradiation. The anatomic distribution of radiation dose was reconstructed in the sagittal plane for the patient who developed radiation myelopathy and in the axial plane for the patient who developed peripheral neuropathy. The actual dose delivered to the injured structure in each patient was taken from the dose distribution and recorded along with the time, number of fractions, and dose per fraction. The patient who developed radiation myelopathy received a total of 46.5 Gy in twenty-three 2.1 Gy fractions in 31 days to the upper cervical spinal cord where the thickness of the neck was less than the central axis thickness due to cervical lordosis and absence of a posterior compensating filter. The patient who developed peripheral neuropathy received 55 Gy in twenty-five 2.2 Gy fractions in 50 days to the femoral nerve using bolus over the groins and an anterior one-half value layer Cerrobend pelvic block to bias the dose anteriorly. Compensating filters and other beam attenuators should be used with caution because they may result in unsuspected large-fraction irradiation and total doses of radiation that exceed the tolerance of critical structures.

Evaluation of the gamma radiation shielding parameters of bismuth modified quaternary glass system

Science.gov (United States)

Kaur, Parminder; Singh, K. J.; Thakur, Sonika

2018-05-01

Glasses modified with heavy metal oxides (HMO) are an interesting area of research in the field of gamma-ray shielding. Bismuth modified lithium-zinc-borate glasses have been studied whereby bismuth oxide is added from 0 to 50 mol%. The gamma ray shielding properties of the glasses were evaluated at photon energy 662 keV with the help of XMuDat computer program by using the Hubbell and Seltzer database. Various gamma ray shielding parameters such as attenuation coefficient, shield thickness in terms of half and tenth value layer, effective atomic number have been studied in this work. A useful comparison of this glass system has been made with standard radiation shielding concretes viz. ordinary, barite and iron concrete. The glass samples containing 20 to 50 mol% bismuth oxide have shown better gamma ray shielding properties and hence have the potential to become good radiation absorbers.

Co-localization of a CD1d-binding glycolipid with a radiation-attenuated sporozoite vaccine in LN-resident DCs for a robust adjuvant effect

OpenAIRE

Li, Xiangming; Kawamura, Akira; Andrews, Chasity D.; Miller, Jessica L.; Wu, Douglass; Tsao, Tiffany; Zhang, Min; Oren, Deena; Padte, Neal N.; Porcelli, Steven A.; Wong, Chi-Huey; Kappe, Stefan H. I.; Ho, David D.; Tsuji, Moriya

2015-01-01

A CD1d-binding glycolipid, α-Galactosylceramide (αGalCer), activates invariant natural killer T (iNKT) cells and acts as an adjuvant. We previously identified a fluorinated phenyl ring-modified αGalCer analog, 7DW8-5, displaying nearly 100-fold stronger CD1d binding affinity. In the present study, 7DW8-5 was found to exert a more potent adjuvant effect than αGalCer for a vaccine based on radiation-attenuated sporozoites (RAS) of a rodent malaria parasite, Plasmodium yoelii, also referred to a...

SU-F-J-39: Dose Reduction Strategy Using Attenuation-Based Tube Current Modulation Method in CBCT for IGRT

Energy Technology Data Exchange (ETDEWEB)

Son, K; Lee, H; Kim, C; Cho, S [KAIST, Daejeon (Korea, Republic of); Kim, J [Yonsei Cancer Center, Seoul (Korea, Republic of)

2016-06-15

Purpose: To reduce radiation dose to the patients, tube current modulation (TCM) method has been actively used in diagnostic CT systems. However, TCM method has not yet been applied to a kV-CBCT system on a LINAC machine. The purpose of this study is to investigate whether the use of TCM method is desirable in kV-CBCT system for IGRT. We have developed an attenuation-based tube current modulation (a-TCM) method using the prior knowledge of treatment CT image of a patient. Methods: Patients go through a diagnostic CT scan for RT planning; therefore, using this prior information of CT images, one can estimate the total attenuation of an x-ray through the patient body in a CBCT setting for radiation therapy. We performed a numerical study incorporating major factors into account such as polychromatic x-ray, scatter, noise, and bow-tie filter to demonstrate that a-TCM method can produce equivalent quality of images at reduced imaging radiation doses. Using the CT projector program, 680 projection images of the pediatric XCAT phantom were obtained both in conventional scanning condition, i.e., without modulating the tube current, and in the proposed a-TCM scanning condition. FDK reconstruction algorithm was used for image reconstruction, and the organ dose due to imaging radiation has been calculated in both cases and compared using GATE/Geant4 simulation toolkit. Results: Reconstructed CT images in the a-TCM method showed similar SSIM values and noise properties to the reference images acquired by the conventional CBCT. In addition, reduction of organ doses ranged from 12% to 27%. Conclusion: We have successfully demonstrated the feasibility and dosimetric merit of the a-TCM method for kV-CBCT, and envision that it can be a useful option of CBCT scanning that provides patient dose reduction without degrading image quality.

Radiation exposure reduction by use of Kevlar cassettes in the neonatal nursery

International Nuclear Information System (INIS)

Herman, M.W.; Mak, H.K.; Lachman, R.S.

1987-01-01

A study was performed to determine whether the use of Kevlar cassettes in the neonatal intensive care nursery would reduce radiation exposure to patients. The radiation dose to the neonates was measured by using thermoluminescent dosimeters. In addition, the attenuation of the Kevlar cassettes and the sensitivity of the film-screen combination were compared with the previously used system. The greatest radiation reduction using a mobile X-ray unit was 27%; based on sensitivity measurements, the theoretical reduction averaged 38%. The reduction in radiation exposure resulted from reduced attenuation by the Kevlar cassette

Fuzzy clustering-based segmented attenuation correction in whole-body PET

CERN Document Server

Zaidi, H; Boudraa, A; Slosman, DO

2001-01-01

Segmented-based attenuation correction is now a widely accepted technique to reduce noise contribution of measured attenuation correction. In this paper, we present a new method for segmenting transmission images in positron emission tomography. This reduces the noise on the correction maps while still correcting for differing attenuation coefficients of specific tissues. Based on the Fuzzy C-Means (FCM) algorithm, the method segments the PET transmission images into a given number of clusters to extract specific areas of differing attenuation such as air, the lungs and soft tissue, preceded by a median filtering procedure. The reconstructed transmission image voxels are therefore segmented into populations of uniform attenuation based on the human anatomy. The clustering procedure starts with an over-specified number of clusters followed by a merging process to group clusters with similar properties and remove some undesired substructures using anatomical knowledge. The method is unsupervised, adaptive and a...

Spectral properties of plant leaves pertaining to urban landscape design of broad-spectrum solar ultraviolet radiation reduction

Science.gov (United States)

Yoshimura, Haruka; Zhu, Hui; Wu, Yunying; Ma, Ruijun

2010-03-01

Human exposure to harmful ultraviolet (UV) radiation has important public health implications. Actual human exposure to solar UV radiation depends on ambient UV irradiance, and the latter is influenced by ground reflection. In urban areas with higher reflectivity, UV exposure occurs routinely. To discover the solar UV radiation regulation mechanism of vegetation, the spectral reflectance and transmittance of plant leaves were measured with a spectrophotometer. Typically, higher plants have low leaf reflectance (around 5%) and essentially zero transmittance throughout the UV region regardless of plant species and seasonal change. Accordingly, incident UV radiation decreases to 5% by being reflected and is reduced to zero by passing through a leaf. Therefore, stratified structures of vegetation are working as another terminator of UV rays, protecting whole terrestrial ecosystems, while vegetation at waterfronts contributes to protect aquatic ecosystems. It is possible to protect the human population from harmful UV radiation by urban landscape design of tree shade and the botanical environment. Even thin but uniformly distributed canopy is effective in attenuating UV radiation. To intercept diffuse radiation, UV screening by vertical structures such as hedges should be considered. Reflectivity of vegetation is around 2%, as foliage surfaces reduce incident UV radiation via reflection, while also eliminating it by transmittance. Accordingly, vegetation reduces incident UV radiation to around 2% by reflection. Vegetation influence on ambient UV radiation is broad-spectrum throughout the UV region. Only trees provide cool UV protective shade. Urban landscapes aimed at abating urban heat islands integrated with a reduction of human UV over-exposure would contribute to mitigation of climate change.

Semiconductor high-energy radiation scintillation detector

International Nuclear Information System (INIS)

Kastalsky, A.; Luryi, S.; Spivak, B.

2006-01-01

We propose a new scintillation-type detector in which high-energy radiation generates electron-hole pairs in a direct-gap semiconductor material that subsequently recombine producing infrared light to be registered by a photo-detector. The key issue is how to make the semiconductor essentially transparent to its own infrared light, so that photons generated deep inside the semiconductor could reach its surface without tangible attenuation. We discuss two ways to accomplish this, one based on doping the semiconductor with shallow impurities of one polarity type, preferably donors, the other by heterostructure bandgap engineering. The proposed semiconductor scintillator combines the best properties of currently existing radiation detectors and can be used for both simple radiation monitoring, like a Geiger counter, and for high-resolution spectrography of the high-energy radiation. An important advantage of the proposed detector is its fast response time, about 1 ns, essentially limited only by the recombination time of minority carriers. Notably, the fast response comes without any degradation in brightness. When the scintillator is implemented in a qualified semiconductor material (such as InP or GaAs), the photo-detector and associated circuits can be epitaxially integrated on the scintillator slab and the structure can be stacked-up to achieve virtually any desired absorption capability

Evaluation of the sealing properties and TMA study of multilayer PA/PE film treated with e-beam radiation

International Nuclear Information System (INIS)

Ortiz, Angel V.; Gargalaka Junior, Joao; Wiebeck, Helio

2007-01-01

Multilayer films are widely used in the food industry as thermoforming as well as non thermoforming vacuum packaging. In this study a PA6/LDPE multilayer film underwent E-beam radiation and its sealing properties were evaluated over 3 years after the film was irradiated. Packaging materials have been widely processed by ionizing radiation in order to improve their chemical and physical properties and also for sterilization purposes. Basically, flexible packaging manufacturers apply specific radiation doses to promote cross-linking and scission of the polymeric chains and thus obtain alterations in certain properties. While enhancing a specific property, significant losses may result in others. We examined the effects of E-beam radiation on the sealing properties of the multilayer film irradiated with doses up to 127 kGy. Results showed that as doses go up, the sealing strength goes down. The TMA study shows that the softening/melting temperatures of the LDPE layer (sealing layer) varies according to the irradiation doses and helps explain the results of the sealing strength tests. (author)

Assessment of satellite derived diffuse attenuation coefficients ...

Science.gov (United States)

Optical data collected in coastal waters off South Florida and in the Caribbean Sea between January 2009 and December 2010 were used to evaluate products derived with three bio-optical inversion algorithms applied to MOIDS/Aqua, MODIS/Terra, and SeaWiFS satellite observations. The products included the diffuse attenuation coefficient at 490 nm (Kd_490) and for the visible range (Kd_PAR), and euphotic depth (Zeu, corresponding to 1% of the surface incident photosynthetically available radiation or PAR). Above-water hyperspectral reflectance data collected over optically shallow waters of the Florida Keys between June 1997 and August 2011 were used to help understand algorithm performance over optically shallow waters. The in situ data covered a variety of water types in South Florida and the Caribbean Sea, ranging from deep clear waters, turbid coastal waters, and optically shallow waters (Kd_490 range of ~0.03 – 1.29m-1). An algorithm based on Inherent Optical Properties (IOPs) showed the best performance (RMSD turbidity or shallow bottom contamination. Similar results were obtained when only in situ data were used to evaluate algorithm performance. The excellent agreement between satellite-derived remote sensing reflectance (Rrs) and in situ Rrs suggested that

Starch Digestibility and Functional Properties of Rice Starch Subjected to Gamma Radiation

Directory of Open Access Journals (Sweden)

Luís Fernando Polesi

2018-01-01

Full Text Available This study investigated the effect of gamma radiation on the digestibility and functional properties of rice starch. Rice cultivars IRGA417 and IAC202 were used for isolation of starch by the alkaline method. Starch samples were irradiated with 1, 2 and 5 kGy doses of 60Co at a rate of 0.4 kGy/h. A control sample, which was not irradiated, was used for comparison. Irradiated and control starches were characterized by in vitro starch digestibility, total dietary fiber, color, water absorption index, water solubility index, syneresis, swelling factor, amylose leaching, pasting properties and gel firmness. Irradiations changed starch digestibility differently in either cultivar. Increasing radiation doses promoted increase in the color parameter b* (yellow, elevation in the capacity to absorb water, and solubility in water as well as the amylose leached from granules for both cultivars. Pasting properties showed a decrease that was proportional to the dose applied, caused by the depolymerization of starch molecules. Gel firmness of the starch from IAC202 was inversely proportional to the radiation dose applied, whereas for IRGA417, there was a reduction at 5 kGy dose. Rice starches can be modified by irradiation to exhibit different functional characteristics and they can be used by the food industries in products such as soups, desserts, flans, puddings and others.

Radiation Background and Attenuation Model Validation and Development

Energy Technology Data Exchange (ETDEWEB)

Peplow, Douglas E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Santiago, Claudio P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2015-08-05

This report describes the initial results of a study being conducted as part of the Urban Search Planning Tool project. The study is comparing the Urban Scene Simulator (USS), a one-dimensional (1D) radiation transport model developed at LLNL, with the three-dimensional (3D) radiation transport model from ORNL using the MCNP, SCALE/ORIGEN and SCALE/MAVRIC simulation codes. In this study, we have analyzed the differences between the two approaches at every step, from source term representation, to estimating flux and detector count rates at a fixed distance from a simple surface (slab), and at points throughout more complex 3D scenes.

Attenuation of a non-parallel beam of gamma radiation by thick shielding-application to the determination of the {sup 235}U enrichment with NaI detectors

Energy Technology Data Exchange (ETDEWEB)

Mortreau, Patricia [European Commission, Joint Research Centre, Institute for the Protection and Security of the Citizen, TP 800 Via Fermi, Ispra (Vatican City State, Holy See,) (Italy)]. E-mail: patricia.mortreau@jrc.it; Berndt, Reinhard [European Commission, Joint Research Centre, Institute for the Protection and Security of the Citizen, TP 800 Via Fermi, Ispra (VA) (Italy)

2005-09-21

The traditional method used to determine the Uranium enrichment by nondestructive analysis is based on the 'enrichment meter principle' [1]. It involves measuring the intensity of the 186 keV net peak area of {sup 235}U in 'quasi-infinite' samples. A prominent factor, which affects the peak intensity, is the presence of gamma absorbing material (e.g., container wall, detector cover) between the sample and the detector. Its effect is taken into consideration in a commonly called 'wall thickness' correction factor. Often calculated on the basis of approximations, its performance is adequate for small attenuation factors applicable to the case of narrow beams. However these approximations do not lead to precise results when wide non-parallel beams are attenuated through thick container walls. This paper is dedicated to the calculation by numerical integration of the geometrical correction factor (K {sub wtc}) which describes the effective mean path length of the radiation through the absorbing layer. This factor was calculated as a function of various measurement parameters (types and dimensions of the detector, of the collimator and of the shielding) for the most commonly used collimator shapes and detectors. Both coherent scattering (Rayleigh) and incoherent scattering (Compton) are taken into account for the calculation of the radiation interaction within the detector.

Shielding properties of the ordinary concrete loaded with micro- and nano-particles against neutron and gamma radiations.

Science.gov (United States)

Mesbahi, Asghar; Ghiasi, Hosein

2018-06-01

The shielding properties of ordinary concrete doped with some micro and nano scaled materials were studied in the current study. Narrow beam geometry was simulated using MCNPX Monte Carlo code and the mass attenuation coefficient of ordinary concrete doped with PbO 2 , Fe 2 O 3 , WO 3 and H 4 B (Boronium) in both nano and micro scales was calculated for photon and neutron beams. Mono-energetic beams of neutrons (100-3000 keV) and photons (142-1250 keV) were used for calculations. The concrete doped with nano-sized particles showed higher neutron removal cross section (7%) and photon attenuation coefficient (8%) relative to micro-particles. Application of nano-sized material in the composition of new concretes for dual protection against neutrons and photons are recommended. For further studies, the calculation of attenuation coefficients of these nano-concretes against higher energies of neutrons and photons and different particles are suggested. Copyright © 2018 Elsevier Ltd. All rights reserved.

Factors Influencing Virulence and Plaque Properties of Attenuated Venezuelan Equine Encephalomyelitis Virus Populations

Science.gov (United States)

Hearn, Henry J.; Seliokas, Zenonas V.; Andersen, Arthur A.

1969-01-01

A minority of stable large-plaque virus increased proportionally in stored unstable attenuated (9t) Venezuelan equine encephalomyelitis virus populations. L-cell-grown progeny (9t2) of stored 9t showed large amounts of large-plaque virus and increased virulence. Small-plaque virus inhibited large-plaque virus but not the reverse. Serial passage of small-plaque virus from 9t2 yielded a strain (20t) that was more attenuated than 9t. PMID:5823235

Reduction of Radiation-Induced Changes in Biophysical Properties of Erythrocytes

International Nuclear Information System (INIS)

El-Marakby, S.M.A.

2014-01-01

group received continuous administration for two weeks before and two other weeks after irradiation (total time of administration 28 days). While the mitigation effect of poly-MVA was evaluated by its daily administration immediately after irradiation for two weeks. Measurements had been carried out include determination of cellular antioxidant enzymes (Glutathione (GSH), catalase and superoxide dismutase) and lipid peroxidation in liver homogenate. The rheological properties of blood, electrical properties, osmotic fragility and scanning electron microscope photography of erythrocytes were also performed. The electrical properties of erythrocytes suspension were measured in the frequency range 40 kHz to 5 MHz using LCR meter HIOKI 3531. The erythrocyte normal hemolysis, mean corpuscular hemoglobin concentration, mean corpuscular volume, hemoglobin concentration and hematocrit were also measured. The results showed that exposure to radiation resulted in a significant decrease in cellular antioxidant enzymes (GSH, Catalase and SOD) and decrease in the AC conductivity, relative permittivity, area under the loss curve, membrane effective capacitance, blood Bingham viscosity, yield stress and aggregation index. Furthermore it induced slightly increase in average osmotic fragility of erythrocytes accompanied by decrease in osmotic dispersion and remarkable modification of erythrocytes morphology. It also caused significant increase (75%) in the lipid peroxidation 1 day after exposure to radiation. The later change persisted until the 14th day recorded after irradiation. Oral uptake of poly-MVA showed markedly elevation in the concentration of antioxidant enzymes (GSH, Catalase and SOD), while it produced a significant decrease in blood Bingham viscosity and yield stress with a non significant change in aggregation index, accompanied by a significant increase in average osmotic hemolysis and osmotic dispersion which continued increasing with time of poly-MVA administration

Symphony orchestra musicians′ use of hearing protection and attenuation of custom-made hearing protectors as measured with two different real-ear attenuation at threshold methods

Directory of Open Access Journals (Sweden)

K H Huttunen

2011-01-01

Full Text Available Despite a high level of sound exposure and a fairly large selection of earplugs available, musicians have often been reported to use personal hearing protectors only seldom. For better hearing conservation, it is important to identify and eliminate the causes for the low motivation to use hearing protection. We explored the usage rate of custom-molded musician′s earplugs (ER-15 among 15 symphony orchestra musicians with a questionnaire, and measured the attenuation properties of their earplugs with a Real-Ear Attenuation at Threshold (REAT procedure in a sound field. Earplug use was found to be low, and the musicians reported that earplugs hampered listening to their own and their colleagues′ playing; earplugs affected either timbre or dynamics, or both. Additionally, several reasons related to discomfort of use were itemized, but the musicians who consistently used their earplugs did so in spite of problems with use. The REAT values obtained in sound field were relatively close to the manufacturer′s nominal specifications, being 13.7 dB, on average. In the frequency range studied (0.125-8 kHz, individual variation in REAT was, however, up to 15 dB across the measured frequencies. Fluctuation in attenuation might be related to low use of hearing protectors, and REAT measured at fixed center frequencies may be too robust a method to uncover it. We therefore tested 10 additional subjects to find out whether a sweeping signal used in Bιkιsy audiometry would bring more detailed information on earplug attenuation. Mean attenuation was found to be somewhat closer to the nominal attenuation of the ER-9 and ER-15 earplugs up to about 1 kHz, whereas REAT measurements in sound field revealed more even attenuation at frequencies between 1 and 6 kHz. No significant association was found between earplug attenuation properties and earplug use. It was concluded that support and determination to get accustomed to hearing protector use are important

Program description of FIBRAM (Fiber Optic Radiation Attenuation Model): a radiation attenuation model for optical fibers

International Nuclear Information System (INIS)

Ingram, W.J.

1987-06-01

The report describes a fiber-optics system model and its computer implementation. This implementation can calculate the bit error ratio (BER) versus time for optical fibers that have been exposed to gamma radiation. The program is designed so that the user may arbitrarily change any or all of the system input variables and produce separate outputs. The primary output of the program is a table of the BER as a function of time. This table may be stored on magnetic media and later incorporated into computer graphic programs. The program was written in FORTRAN 77 for the IBM PC/AT/XT computers. Flow charts and program listings are included in the report

Mapping Pn amplitude spreading and attenuation in Asia

Energy Technology Data Exchange (ETDEWEB)

Yang, Xiaoning [Los Alamos National Laboratory; Phillips, William S [Los Alamos National Laboratory; Stead, Richard J [Los Alamos National Laboratory

2010-12-06

Pn travels most of its path in the mantle lid. Mapping the lateral variation of Pn amplitude attenuation sheds light on material properties and dynamics of the uppermost region of the mantle. Pn amplitude variation depends on the wavefront geometric spreading as well as material attenuation. We investigated Pn geometric spreading, which is much more complex than a traditionally assumed power-law spreading model, using both synthetic and observed amplitude data collected in Asia. We derived a new Pn spreading model based on the formulation that was proposed previously to account for the spherical shape of the Earth (Yang et. al., BSSA, 2007). New parameters derived for the spreading model provide much better correction for Pn amplitudes in terms of residual behavior. Because we used observed Pn amplitudes to construct the model, the model incorporates not only the effect of the Earth's spherical shape, but also the effect of potential upper-mantle velocity gradients in the region. Using the new spreading model, we corrected Pn amplitudes measured at 1, 2, 4 and 6 Hz and conducted attenuation tomography. The resulting Pn attenuation model correlates well with the regional geology. We see high attenuation in regions such as northern Tibetan Plateau and the western Pacific subduction zone, and low attenuation for stable blocks such as Sichuan and Tarim basins.

Effects of 60Co gamma radiation on crotamine

Directory of Open Access Journals (Sweden)

Boni-Mitake M.

2001-01-01

Full Text Available Ionizing radiation can change the molecular structure and affect the biological properties of biomolecules. This has been employed to attenuate animal toxins. Crotamine is a strongly basic polypeptide (pI 10.3 from Crotalus durissus terrificus venom composed of 42 amino acid residues. It induces skeletal muscle spasms leading to a spastic paralysis of hind limbs in mice. The objective of the present study was to carry out a biochemical study and a toxic activity assay on native and irradiated crotamine. Crotamine was purified from C.d. terrificus venom by Sephadex G-100 gel filtration followed by ion-exchange chromatography, and irradiated at 2 mg/ml in 0.15 M NaCl with 2.0 kGy gamma radiation emitted by a 60Co source. The native and irradiated toxins were evaluated in terms of structure and toxic activity (LD50. Irradiation did not change the protein concentration, the electrophoretic profile or the primary structure of the protein although differences were shown by spectroscopic techniques. Gamma radiation reduced crotamine toxicity by 48.3%, but did not eliminate it.

Mechanical properties in polypropylene-polyethylene blends modified by gamma radiation

International Nuclear Information System (INIS)

Ruiz, F.C.; Terence, M.C.

2008-01-01

One of the way to obtain a better mechanical property of polypropylene and polyethylene is related to increase the number polymer chains cross-linked by gamma radiation. After irradiation a network is formed which is the result of various chemical reactions occurred during this process, where the radicals formed are concentrated in the amorphous phase. With the objective to increase the mechanical properties of PP, blends with PE were prepared and irradiated in doses up to 100kGy, in atmospheric ambient. The tests showed increase in rigidity and a particular behaviour in Izod impact resistance. (author)

Basic radiation sterilization properties of packaging materials

International Nuclear Information System (INIS)

Zouharova, A.; Kolarova, J.; Olbrichova, D.

1984-01-01

The foils of various materials were irradiated with 60 Co with an activity of 11,538 TBq. The minimum radiation dose was 25 kGy. Changes in chemico-physical properties were evaluated by infrared spectroscopy and were not detected after irradiation with 25 kGy. Packing foils were subjected to the following tests: mechanical tests, tests of weld strength, tests of impact resistance, free fall tests, permeability tests for water vapour and microbiological tests. The results of all tests were tabulated. The tests showed that the foils are impermeable for microorganisms and provided the welds are airtight the packed products remain sterile. (J.P.)

Gamma radiation effects on the structure and properties of polystyrene

International Nuclear Information System (INIS)

Lima, Ivania Soares de

1996-01-01

Polystyrene is a linear thermoplastic with a molecular weight ranging from 130,000 to 300,000 g/mole. This polymer has wide industrial applications. In medicine it is used to manufacture medical supplies which can be sterilized by ionizing radiation. The sterilization of medical instruments by ionizing radiation was introduced in the 60's as an alternative method to the conventional treatment with ethylene oxide gas. Radiosterilization is now worldwide standard procedure, as it is cheaper and cleaner. Some polymers, however, may show some changes in their physical properties following irradiation. These changes are due to the prevailing crosslinking and main chain scission induced by the irradiation of the polymeric system. In the present work, Brazilian-made polystyrene Lustrex was irrigated with γ rays in the presence of air at room temperature. Under these conditions, the analysis of viscosimetric essays showed the prevalence of crosslinking effects at doses up to 25 kGy and of main scission effects at does from 25 to 200 kGy. Observed G values (number of events per 100 eV of absorbed energy) pointed to low degrees of both crosslinking (Gx ∼ 0.15) and main chain scission (Gs ∼ 0.09). Therefore, the minor changes in Lustrex's molecular structure induced by irradiation have not influenced significantly its mechanical, thermal, and optical properties. As a result, Lustrex can be used in applications involving radiation without the need to introduce radioprotective to the polymeric system. (author)

Effect of low-intensity electromagnetic radiation on structurization properties of bacterial lipopolysaccharide

Directory of Open Access Journals (Sweden)

Grigory E. Brill

2014-09-01

Full Text Available Purpose — to investigate the effects of low-intensity electromagnetic radiation on the process of dehydration selforganization of bacterial lipopolysaccharide (LPS. Material and Methods — The method of wedge dehydration has been used to study the structure formation of bacterial LPS. Image-phases analysis included their qualitative characteristics, as well as the calculation of quantitative indicators, followed by statistical analysis. Results — Low-intensity ultra high frequency (UHF radiation (1 GHz, 0.1 μW/cm2, 10 min has led to the changes in the suspension system of the LPS-saline reflected in the kinetics of structure formation. Conclusion — 1 GHz corresponds to the natural frequency of oscillation of water clusters and, presumably, the effect of UHF on structure of LPS mediates through the changes in water-salt environment. Under these conditions, properties of water molecules of hydration and possibly the properties of hydrophobic and hydrophilic regions in the molecule of LPS, which can affect the ability of toxin molecules to form aggregates change. Therefore the LPS structure modification may result in the change of its toxic properties.

MONITORED NATURAL ATTENUATION AND RISK MANAGEMENT OF MTBE AND TBA IN GROUND WATER

Science.gov (United States)

Monitored natural attenuation (as U.S. EPA defines the term) is a remedy, where natural processes bring the concentration of MTBE or TBA to an acceptable level in a reasonable period of time. The longevity of the plume is its critical property. The rate of attenuation is typica...

Waste Tire Particles and Gamma Radiation as Modifiers of the Mechanical Properties of Concrete

Directory of Open Access Journals (Sweden)

Eduardo Sadot Herrera-Sosa

2014-01-01

Full Text Available In polymer reinforced concrete, the Young’s modulus of both polymers and cement matrix is responsible for the detrimental properties of the concrete, including compressive and tensile strength, as well as stiffness. A novel methodology for solving such problems is based on use of ionizing radiation, which has proven to be a good tool for improvement on physical and chemical properties of several materials including polymers, ceramics, and composites. In this work, particles of 0.85 mm and 2.80 mm obtained from waste tire were submitted at 250 kGy of gamma radiation in order to modify their physicochemical properties and then used as reinforcement in Portland cement concrete for improving mechanical properties. The results show diminution on mechanical properties in both kinds of concrete without (or with irradiated tire particles with respect to plain concrete. Nevertheless such diminutions (from 2 to 16% are compensated with the use of high concentration of waste tire particles (30%, which ensures that the concrete will not significantly increase the cost.

Quantitative contrast-enhanced CT attenuation evaluation of osseous metastases following chemotherapy

Energy Technology Data Exchange (ETDEWEB)

Chang, Connie Y.; Simeone, F.J.; Torriani, Martin; Bredella, Miriam A. [Massachusetts General Hospital, Division of Musculoskeletal Imaging and Intervention, Department of Radiology, Boston, MA (United States)

2017-10-15

Osseous metastases often undergo an osteoblastic healing response following chemotherapy. The purpose of our study was to demonstrate the quantitative CT changes in attenuation of osseous metastases before and after chemotherapy. Our study was IRB approved and HIPAA compliant. Our cohort consisted of 86 consecutive cancer patients with contrast-enhanced CTs before and 14 ± 2 (12-25) months after initiation of chemotherapy (60 ± 11 years, 36 males, 50 females). The average and maximum metastasis attenuations were measured in Hounsfield units (HU) by two readers. Treatment effects were assessed using paired t-tests and Fisher exact tests. Intraclass correlation coefficients (ICCs) were calculated. Patient records were reviewed to determine the patient's clinical status (worse, unchanged, or improved) at the time of follow-up CT. The distribution of lesion types was as follows: lytic (30/86, 35%), blastic (43/86, 50%), and mixed lytic-blastic (13/86, 15%). There was a significant increase in average and maximum CT attenuation of metastases following chemotherapy for all patients, which remained statistically significant when stratified by lesion type, clinical status (worsening or improving/stable), cancer type (breast, lung), and radiation therapy (P < 0.05). In a subgroup of patients whose osseous metastases decreased in average attenuation (14/86, 16%), more patients had a worse clinical status (11/14, 79%) (P = 0.02). ICC was almost perfect for average attenuation and substantial for maximum attenuation. Quantitative assessment of osseous metastatic disease using CT attenuation measurements demonstrated a statistically significant increase in attenuation more than 12 months after initiation of chemotherapy. (orig.)

The shielding against radiation produced by powder metallurgy with tungsten copper alloy applied on transport equipment for radio-pharmaceutical products

International Nuclear Information System (INIS)

Cione, Francisco C.; Sene, Frank F.; Souza, Armando C. de; Betini, Evandro G.; Rossi, Jesualdo L.; Rizzuto, Marcia A.

2015-01-01

Safety is mandatory on medicine radiopharmaceutical transportation and dependent on radiation shielding material. The focus of the present work is to minimize the use of harmful materials as lead and depleted uranium usually used in packages transportation. The tungsten-copper composite obtained by powder metallurgy (PM) is non-toxic. In powder metallurgy the density and the porosity of the compacted parts depends basically upon particle size distribution of each component, mixture, compacting pressure and sintering temperature cycle. The tungsten-copper composite, when used for shielding charged particles, X-rays, gamma photons or other photons of lower energy require proper interpretation of the radiation transport phenomena. The radioactive energy reduction varies according to the porosity and density of the materials used as shielding. The main factor for radiation attenuation is the cross section value for tungsten. The motivation research factor is an optimization of the tungsten and cooper composition in order to achieve the best linear absorption coefficient given by equation I (x) = I 0 e (-ux) . Experiments were conducted to quantify the effective radiation shielding properties of tungsten-copper composite produced by PM, varying the cooper amount in the composite. The studied compositions were 15%, 20% and 25% copper in mass. The Compaction pressure was 270 MPa and the sintering atmosphere was in 1.1 atm in N 2 +H 2 . The sintering temperature was 980 deg C for 2 h. The linear absorption coefficient factor was similar either for the green and the sintered compacts, due the amount of porosity did not affect the radiation attenuation. Thus the sintered was meant for size reduction and mechanical properties enhancement. (author)

The shielding against radiation produced by powder metallurgy with tungsten copper alloy applied on transport equipment for radio-pharmaceutical products

Energy Technology Data Exchange (ETDEWEB)

Cione, Francisco C.; Sene, Frank F.; Souza, Armando C. de; Betini, Evandro G.; Rossi, Jesualdo L., E-mail: fceoni@hotmail.com, E-mail: ffsene@hotmail.com, E-mail: armandocirilo@yahoo.com, E-mail: evandrobetini@gmail.com, E-mail: jelrossi@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Rizzuto, Marcia A., E-mail: marizzutto@if.usp.br [Universidade de Sao Paulo (IF/USP), SP (Brazil). Instituto de Fisica

2015-07-01

Safety is mandatory on medicine radiopharmaceutical transportation and dependent on radiation shielding material. The focus of the present work is to minimize the use of harmful materials as lead and depleted uranium usually used in packages transportation. The tungsten-copper composite obtained by powder metallurgy (PM) is non-toxic. In powder metallurgy the density and the porosity of the compacted parts depends basically upon particle size distribution of each component, mixture, compacting pressure and sintering temperature cycle. The tungsten-copper composite, when used for shielding charged particles, X-rays, gamma photons or other photons of lower energy require proper interpretation of the radiation transport phenomena. The radioactive energy reduction varies according to the porosity and density of the materials used as shielding. The main factor for radiation attenuation is the cross section value for tungsten. The motivation research factor is an optimization of the tungsten and cooper composition in order to achieve the best linear absorption coefficient given by equation I{sub (x)} = I{sub 0}e{sup (-ux)}. Experiments were conducted to quantify the effective radiation shielding properties of tungsten-copper composite produced by PM, varying the cooper amount in the composite. The studied compositions were 15%, 20% and 25% copper in mass. The Compaction pressure was 270 MPa and the sintering atmosphere was in 1.1 atm in N{sub 2}+H{sub 2}. The sintering temperature was 980 deg C for 2 h. The linear absorption coefficient factor was similar either for the green and the sintered compacts, due the amount of porosity did not affect the radiation attenuation. Thus the sintered was meant for size reduction and mechanical properties enhancement. (author)

The selection and properties of epoxide resins used for the insulation of magnet systems in radiation environments

International Nuclear Information System (INIS)

Phillips, D.C.; Scott, J.M.; Goebel, K.; Schoenbacher, H.

1981-01-01

Laboratory tests have been carried out on five types of epoxy resins - four based on bisphenol A, one on hydantoin-bisphenol A - applicable in the construction of large magnet coils. Two of the resin compositions have already been used in large quantities as insulating material for magnets at the European Organization for Nuclear Research (CERN); the others were selected for comparison according to their good radiation resistance, good initial mechanical properties, and optimal properties for vacuum impregnation. Three types of tests are discussed in detail: creep, crack propagation (as a measure of toughness), and radiation resistance. The results show that the resin composition with hydantoin exhibits the best resistance to crack propagation but, on the other hand, the lowest resistance to ionizing radiation, and can therefore not be recommended for use in a radiation environment. Among the other materials based on biosphenol A, better toughness values were obtained with lower-cross-linked resin systems, whereas the radiation resistance is better for highly-cross-linked materials. It is concluded that a reasonable compromise combining good processing and operational properties with sufficiently high radiation resistance is obtained with a standard epoxy-resin-type bisphenol A with a specially formulated anhydride hardener and an amine-substituted phenol-type accelerator. (orig.)

Assessment of precipitates of isothermal aged austenitic stainless steel using measurement techniques of ultrasonic attenuation

International Nuclear Information System (INIS)

Kim, Hun Hee; Kim, Hak Joon; Song, Sung Jin; Lim, Byeong Soo; Kim, Kyung Cho

2014-01-01

AISI 316L stainless steel is widely used as a structural material of high temperature thermoelectric power plants, since austenitic stainless steel has excellent mechanical properties. However, creep damage is generated in these components, which are operated under a high temperature and high pressure environment. Several researches have been done on how microstructural changes of precipitates affect to the macroscopic mechanical properties. And they investigate the relation between ultrasonic parameters and metallurgical results. But, these studies are limited by experiment results only. In this paper, attenuations of ultrasonic with isothermal damaged AISI 316L stainless steel were measured. Also, simulation of ultrasonic attenuation with variation of area fraction and size of precipitates were performed. And, from the measured attenuations, metallographic data and simulation results, we investigate the relations between the ultrasonic attenuations and the material properties which is area fraction of precipitates for the isothermal damaged austenitic stainless steel specimens. And, we studied parametric study for investigation of the relation between ultrasonic parameters and metallurgical results of the isothermal damaged AISI 316L stainless steel specimens using numerical methods.

Effect of electron beam radiation processing on mechanical and thermal properties of fully biodegradable crops straw/poly (vinyl alcohol) biocomposites

Science.gov (United States)

Guo, Dan

2017-01-01

Fully biodegradable biocomposites based on crops straw and poly(vinyl alcohol) was prepared through thermal processing, and the effect of electron beam radiation processing with N,N-methylene double acrylamide as radiation sensitizer on mechanical and thermal properties of the biocomposites were investigated. The results showed that, when the radiation dose were in the range of 0-50 kGy, the mechanical and thermal properties of the biocomposites could be improved significantly through the electron beam radiation processing, and the interface compatibility was also improved because of the formation of stable cross-linked network structure, when the radiation dose were above the optimal value (50 kGy), the comprehensive properties of the biocomposites were gradually destroyed. EB radiation processing could be used as an effective technology to improve the comprehensive performance of the biocomposites, and as a green and efficient processing technology, radiation processing takes place at room temperature, and no contamination and by-product are possible.

Influence of ionizing radiation on the mechanical properties of BisGMA/TEGDMA based experimental resin

International Nuclear Information System (INIS)

LMP, Campos; Boaro, LC; LKG, Santos; Parra, DF; Lugão, AB

2015-01-01

Dental restorative composites are activated by visible light and the polymerization process, known as direct technique, is initiated by absorbing light in a specific wavelength range (450–500 nm). However this technique presented some disadvantages. If light is not inserted correctly, layers uncured can cause countless damage to restoration, especially with regard to mechanical properties. A clinical alternative used to reduce the shortcomings of direct application is the use of composite resins for indirect application. These composites are adaptations of resins prepared for direct use, with differences mainly in the healing process. Besides the traditional photoactivation, indirect application composites may be submitted to particular curing conditions, such as a slow curing rate, heating, vacuum, and inert-gas pressure leading to an oxygen-free environment. However few studies have been conducted on the process of post-curing by ionizing radiation at low doses. On this sense the purpose of this study was to evaluate possible interactions of ionizing radiation in the post-curing process of the experimental composites based on BisGMA/TEGDMA filled with silica Aerosil OX-50 silanized. Characterization of the experimental composites was performed by thermogravimetry analysis, infrared spectroscopy, elastic modulus and flexural strength. Statistical analysis of results was calculated by one-way ANOVA/Tukey's test. Cross-linking of the polymeric matrix caused by ionizing radiation, influenced the thermal stability of irradiated specimens. FTIR analysis showed that the ionizing radiation induced a post-cure reaction in the specimens. The irradiation dose influenced directly the mechanical properties that showed a strong positive correlation between flexural strength and irradiation and between modulus strength and irradiation. - Highlights: • Interactions of ionizing radiation in BisGMA/TEGDMA experimental dental composites filled with sylanized silica. �

Preparation and properties of hydrogels of PVA/PVP/chitosan by radiation

International Nuclear Information System (INIS)

Nho, Y. C.; Park, K. R.

2001-01-01

The radiation can induce chemical reaction to modify polymer under even the solid condition or in the low temperature. The radiation crosslinking can be easily adjusted and is easily reproducible by controlling the radiation dose. The finished product contains no residuals of substances required to initiate the chemical crosslinking which can restrict the application possibilities. In these studies, hydrogels from a mixture of chitosan and polyvinyl alcohol(PVA)/Poly-N-vinylpyrrolidone(PVP) were made by 'freezing and thawing', or gamma-ray irradiation or two steps of 'freezing and thawing', and gamma-ray irradiation or two steps of 'freezing and thawing' and gamma-ray irradiation for wound dressing. The mechanical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the hydrogels for wound dressing. The composition of PVA:PVP was 60:40, PVA/PVP: chitosan ratio was in the range of 9:1 -7:3, and the solid concentration of PVA/PVP/chitosan solution was 15wt%. Gamma irradiation doses of 25, 35, 50, 60 and 70kGy, respectively were exposed to a mixture of PVA/PVP/chitosan to evaluate the effect of irradiation dose on the mechanical properties of hydrogels. Water-soluble chitosan was used to in this experiment. The mechanical properties of hydrogels such as gelation and gel strength was higher when two steps of 'freezing and thawing' and irradiation were used than only 'freezing and thawing' was utilized. Gel content was influenced slightly by PVA/PVP:chitosan composition and irradiation dose, but swelling was done greatly by them. Swelling percent was much increased as the composition of chitosan in PVA/PVP/chitosan increased

Control of external radiation exposure

International Nuclear Information System (INIS)

Abd Nasir Ibrahim; Azali Muhammad; Ab Razak Hamzah; Abd Aziz Mohamed; Mohammad Pauzi Ismail

2004-01-01

The following subjects are discussed - Control of external radiation exposure: working time, working distance, shielding: Total Linear Attenuation Coefficient, Half-Value Layer (HVL), Tenth-Value Layer (TVL); Build-up Factor

Effect of [sup 60]Co-gamma radiation on the binding properties in furs

Energy Technology Data Exchange (ETDEWEB)

Raina, R K [Regional Research Lab., Srinagar (India)

1992-09-01

New Zealand white rabbit pelts were pickled by the usual procedure and were tanned with basic aluminium sulphate, basic chromium sulphate and their combinations. Tanned furs were irradiated with [sup 60]Co-gamma radiations in the dose range of 5.0-114.0 kGy. The effect of radiation on the binding properties of various added substances like mineral tannins, fats, moisture and shrinkage temperature has been assessed by their comparison with the control samples. The results of these investigations show that radiation on furs causes detannage, increases the moisture and bound fat content and decreases the shrinkage temperature of the furs. (author).

Measurement of fractional x-ray absorption for radiation attenuating surgical gloves

International Nuclear Information System (INIS)

Nagalakshmi, B.; Sawant, S.G.; Nair, C.P.R.; Joshi, V.D.

2000-01-01

It is essential to make use of lead gloves having 0.25 mm lead equivalence only for routine x-ray screening as stipulated by International Commission on Radiological Protection. Such surgical gloves which provide attenuation to the extent of one half value thickness for low energy are very useful for the present trend of special x-ray examinations which are on the increase

Effect of particle size of mineral fillers on polymer-matrix composite shielding materials against ionizing electromagnetic radiation

International Nuclear Information System (INIS)

Belgin, E.E.; Aycik, G.A.

2017-01-01

Filler particle size is an important particle that effects radiation attenuation performance of a composite shielding material but the effects of it have not been exploited so far. In this study, two mineral (hematite-ilmenite) with different particle sizes were used as fillers in a polymer-matrix composite and effects of particle size on shielding performance was investigated within a widerange of radiation energy (0-2000 keV). The thermal and structural properties of the composites were also examined. The results showed that as the filler particle size decreased the shielding performance increased. The highest shielding performance reached was 23% with particle sizes being between <7 and <74 µm. (author)

Investigation of efficient termination structure for improved breakdown properties of semiconductor radiation detectors

International Nuclear Information System (INIS)

Krizaj, D.; Resnik, D.; Vrtacnik, D.; Amon, S.

1998-01-01

Efficiency of a new junction termination structure for improvement of breakdown properties of semiconductor radiation detectors is investigated. The structure consists of a diffused resistor winding around the active junction in a spiral fashion. The current flow through the spiral enables controlled potential distribution along the spiral turns and thus controlled depletion spreading from the main junction, efficiently preventing premature avalanche breakdown. Both multiple guard-ring structures and spiral junction termination structures have shown good breakdown properties typically three to five times higher than breakdown voltages of diodes without junction termination. The breakdown voltages of spiral junction termination structures are only weakly influenced by changes in substrate doping concentration caused by neutron irradiation. They can thus be considered for termination of future semiconductor radiation detectors

Effects of attenuation map accuracy on attenuation-corrected micro-SPECT images

NARCIS (Netherlands)

Wu, C.; Gratama van Andel, H.A.; Laverman, P.; Boerman, O.C.; Beekman, F.J.

2013-01-01

Background In single-photon emission computed tomography (SPECT), attenuation of photon flux in tissue affects quantitative accuracy of reconstructed images. Attenuation maps derived from X-ray computed tomography (CT) can be employed for attenuation correction. The attenuation coefficients as well

A study on the electric properties of single-junction GaAs solar cells under the combined radiation of low-energy protons and electrons

International Nuclear Information System (INIS)

Zhao Huijie; Wu Yiyong; Xiao Jingdong; He Shiyu; Yang Dezhuang; Sun Yanzheng; Sun Qiang; Lv Wei; Xiao Zhibin; Huang Caiyong

2008-01-01

Displacement damage induced by charged particle radiation is the main cause of degradation of orbital-service solar cells, while the radiation-induced ionization shows no permanent damage effect on their electrical properties. It is reported that in single crystal silicon solar cells, low-energy electron radiation does not exert permanent degradation of their properties, but the fluence of electron radiation exerts an influence on the damage magnitude under the combined radiation of protons and electrons. The electrical properties of the single-junction GaAs/Ge solar cells were investigated after irradiation by sequential and synchronous electron and proton beams. Low-energy electron radiation showed no effects on the change of the solar cell properties during sequential or synchronous irradiation, implying ionization during particle radiation could not exert influence on the displacement damage process to the solar cells under the experimental conditions

Handbook of radiation shielding data

International Nuclear Information System (INIS)

Courtney, J.C.

1976-07-01

This handbook is a compilation of data on units, conversion factors, geometric considerations, sources of radiation, and the attenuation of photons, neutrons, and charged particles. It also includes related topics in health physics. Data are presented in tabular and graphical form with sufficient narrative for a least first-approximation solutions to a variety of problems in nuclear radiation protection. Members of the radiation shielding community contributed the information in this document from unclassified and uncopyrighted sources, as referenced

Short vegetal-fiber reinforced HDPE—A study of electron-beam radiation treatment effects on mechanical and morphological properties

International Nuclear Information System (INIS)

Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R.; Guven, Olgun; Moura, Esperidiana A.B.

2014-01-01

Graphical abstract: - Highlights: • HDPE reinforced with short piassava fiber composites were prepared by melt-mixing processing. • Glycidyl methacrylate (GMA) was tested as a radiation cross-linking agent. • The materials were irradiated with 100 and 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. • The better interfacial adhesion between fiber and HDPE matrix was observed for composites with GMA addition irradiated with radiation dose of 200 kGy. - Abstract: The effects of electron-beam radiation treatment on fiber-matrix adhesion and mechanical properties of short piassava fibers reinforced high density polyethylene (HDPE) matrix were studied. Glycidyl methacrylate (GMA) was added at 2.5% and 5.0% (on piassava fiber wt) as a cross-linking agent and the effects upon the properties of the resulting composites treated by electron-beam radiation were also examined. HDPE reinforced with short piassava fiber composites was prepared by melt-mixing processing, using a twin screw extruder machine. The materials were irradiated with 100 and 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. Material samples were submitted to mechanical and thermo-mechanical tests and SEM analyses. Correlation between properties was discussed. The comparison of mechanical and thermo-mechanical properties of the composites showed that electron-beam radiation treatment produced a significant improvement in mechanical properties, when compared with the non-irradiated composite sample and neat HDPE. Scanning electron microscopy (SEM) studies of the composite failure surfaces indicated that there was an improved adhesion between fiber and matrix. Examination of the failure surfaces indicated dependence of the interfacial adhesion upon the radiation dose and GMA content. Better interfacial adhesion between fiber and HDPE matrix was observed for composites with 5.0% GMA addition and treated with electron

Short vegetal-fiber reinforced HDPE—A study of electron-beam radiation treatment effects on mechanical and morphological properties

Energy Technology Data Exchange (ETDEWEB)

Ferreira, Maiara S.; Sartori, Mariana N.; Oliveira, Rene R. [Nuclear and Energy Research Institute, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, zip code 05508-000 São Paulo, SP (Brazil); Guven, Olgun [Hacettepe University, Department of Chemistry, Polymer Chemistry Division, Beytepe, zip code 06800 Ankara (Turkey); Moura, Esperidiana A.B., E-mail: eabmoura@ipen.br [Nuclear and Energy Research Institute, IPEN-CNEN/SP, Av. Prof. Lineu Prestes 2242, zip code 05508-000 São Paulo, SP (Brazil)

2014-08-15

Graphical abstract: - Highlights: • HDPE reinforced with short piassava fiber composites were prepared by melt-mixing processing. • Glycidyl methacrylate (GMA) was tested as a radiation cross-linking agent. • The materials were irradiated with 100 and 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. • The better interfacial adhesion between fiber and HDPE matrix was observed for composites with GMA addition irradiated with radiation dose of 200 kGy. - Abstract: The effects of electron-beam radiation treatment on fiber-matrix adhesion and mechanical properties of short piassava fibers reinforced high density polyethylene (HDPE) matrix were studied. Glycidyl methacrylate (GMA) was added at 2.5% and 5.0% (on piassava fiber wt) as a cross-linking agent and the effects upon the properties of the resulting composites treated by electron-beam radiation were also examined. HDPE reinforced with short piassava fiber composites was prepared by melt-mixing processing, using a twin screw extruder machine. The materials were irradiated with 100 and 200 kGy using a 1.5 MeV electron beam accelerator, at room temperature in presence of air. Material samples were submitted to mechanical and thermo-mechanical tests and SEM analyses. Correlation between properties was discussed. The comparison of mechanical and thermo-mechanical properties of the composites showed that electron-beam radiation treatment produced a significant improvement in mechanical properties, when compared with the non-irradiated composite sample and neat HDPE. Scanning electron microscopy (SEM) studies of the composite failure surfaces indicated that there was an improved adhesion between fiber and matrix. Examination of the failure surfaces indicated dependence of the interfacial adhesion upon the radiation dose and GMA content. Better interfacial adhesion between fiber and HDPE matrix was observed for composites with 5.0% GMA addition and treated with electron

Low-dose radiation attenuates chemical mutagenesis in vivo. Cross adaptation

International Nuclear Information System (INIS)

Kakinuma, Shizuko; Yamauchi, Kazumi; Amasaki, Yoshiko; Nishimura, Mayumi; Shimada, Yoshiya

2009-01-01

The biological effects of low-dose radiation are not only of social concern but also of scientific interest. The radioadaptive response, which is defined as an increased radioresistance by prior exposure to low-dose radiation, has been extensively studied both in vitro and in vivo. Here we briefly review the radioadaptive response with respect to mutagenesis, survival rate, and carcinogenesis in vivo, and introduce our recent findings of cross adaptation in mouse thymic cells, that is, the suppressive effect of repeated low-dose radiation on mutation induction by the alkylating agent N-ethyl-N-nitrosourea. (author)

Physical Properties of P.V.C. Attenuated Network Copolymers Produced by Ionizing Radiation; Proprietes physiques des copolymeres obtenus sous l'action de rayonnements ionisants et dont le reseau est attenue par l'effet du chlorure de polyvinyle; Fizicheskie svojstva polivinilkhloridnykh obednennykh tsepej sopolimerov, poluchennykh v rezul'tate vozdejstviya ioniziruyushchej radiatsii; Propiedades fisicas de los copolimeros de redes atenuadas por cloruro de polivinilo obtenidos por irradiacion

Energy Technology Data Exchange (ETDEWEB)

Pinner, S H [Tube Investments Research Laboratories, Hinxton Hall, Cambridge (United Kingdom)

1960-07-15

The cross-linking of polyvinyl chloride with ionizing radiation poses special problems. Due to rather unfavourable cross-linking and dislinking parameters for this polymer, the radiation doses necessary for high cross-link densities are uneconomicall y large and discolouration and dehydrohalogenatio n are simultaneously produced. These difficulties have been overcome by the incorporation into the P. V. C., prior to irradiation, of diallyl and triallyl esters. Heavily cross-linked products are thereby obtained with relatively low doses of ionizing radiation. Examination of the physical properties of the products suggests that these are not simply graft copolymers, which term normally implies the presence of long branch chains, but are polymer attenuated allyl networks. In these materials, the desirable properties of the parent polymer and of the allyl network are combined. The tensile strength, modulus and elongation of the attenuated network copolymers are presented and discussed as a function of temperature and of the concentration and functionality of the allyl ester. Reference is also made to the swelling and chemical resistance of the products. (author) [French] La reticulation du chlorure de polyvinyle sous l'action des rayonnements ionisants pose des problemes particuliers. Les parametres de reticulation et de degradation etant plutot defavorables pour ce polymere, les doses d'irradiation necessaires a l'obtention de fortes densites de pontage sont trop elevees pour donner des resultats economiquement interessants; elles provoquent simultanement la decoloration et la deshalogenhydratation. Il a ete possible de surmonter ces difficultes par introduction d'esters diallyliques et triallyliques dans le chlorure de polyvinyle, avant irradiation. Ce procede permet d'obtenir au moyen de doses d'irradiation relativement faibles des produits fortement reticules. L'etude des proprietes physiques de ces produits montre qu'il s'agit non pas de simples copolymeres greffes

Effects of {sup 60} Co gamma radiation on crotamine

Energy Technology Data Exchange (ETDEWEB)

Boni-Mitake, M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Dept. de Radioprotecao Ocupacional; Costa, H.; Spencer, P.J. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Dept. de Bioengenharia; Rogero, J.R [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil). Diretoria de Materiais; Vassilieff, V.S. [UNESP, Botucatu, SP (Brazil). Instituto de Biociencias. Ceatox - Centro de Assistencia Toxicologica]. E-mail: mbmitake@net.ipen.br

2001-12-01

Ionizing radiation can change the molecular structure and affect the biological properties of biomolecules. This has been employed to attenuate animal toxins. Crotamine is a strongly basic polypeptide (p I 10.3) from Crotalus durissus terrificus venom composed of 42 amino acid residues. It induces skeletal muscle spasms leading to a spastic paralysis of hind limbs in mice. The objective of the present study was to carry out a biochemical study and a toxic activity assay on native and irradiated crotamine. Crotamine was purified from C.d. terrificus venom by Sephadex G-100 gel filtration followed by ion-exchange chromatography, and irradiated at 2 mg/ml in 0.15 M NaCl with 2.0 kGy gamma radiation emitted by a 60 Co source. The native and irradiated toxins were evaluated in terms of structure and toxic activity (Ld50). Irradiation did not change the protein concentration, the electrophoretic profile or the primary structure of the protein although differences were shown by spectroscopic techniques. Gamma radiation reduced crotamine toxicity by 48.3%, but did not eliminate it. (author)

Calculation extinction cross sections and molar attenuation coefficient of small gold nanoparticles and experimental observation of their UV-vis spectral properties

Science.gov (United States)

Tang, Junqi; Gao, Kunpeng; Ou, Quanhong; Fu, Xuewen; Man, Shi-Qing; Guo, Jie; Liu, Yingkai

2018-02-01

Gold nanoparticles (AuNPs) have been researched extensively, such as applied in various biosensors, biomedical imaging and diagnosis, catalysis and physico-chemical analysis. These applications usually required to know the nanoparticle size or concentration. Researchers have been studying a simply and quick way to estimate the concentration or size of nanoparticles from their optical spectra and SPR feature for several years. The extinction cross-sections and the molar attenuation coefficient were one of the key parameters. In this study, we calculated the extinction cross-sections and molar attenuation coefficient (decadic molar extinction coefficient) of small gold nanoparticles by dipole approximation method and modified Beer-Lambert law. The theoretical result showed that the surface plasmon resonance peak of small gold nanoparticles was blueshift with an increase size. Moreover, small AuNPs (sub-10 nm) were prepared by using of dextran or trisodium citrate as reducing agent and capping agent. The experimental synthesized AuNPs was also shows a blueshift as increasing particle size in a certain range. And the concentration of AuNPs was calculated based on the obtained molar attenuation coefficient. For small nanoparticles, the size of nanoparticles and surface plasmon resonance property was not showed a positive correlation compared to larger nanoparticles. These results suggested that SPR peak depended not only on the nanoparticle size and shape but also on the nanoparticles environment.

Gamma ray attenuation studies on concrete reinforced with coconut shells

International Nuclear Information System (INIS)

Vishnu, C.V.; Antony, Joseph

2017-01-01

The fact that radiation could be harmful has led to the development of wide variety of shields to protect against it. For nuclear radiation shielding, a larger quantity of shielding material is required and therefore, the study of propagation of radiation flux in shielding materials is an essential requirement for shield design. Concrete has proven to be an excellent and versatile shielding material with well-established linear attenuation for neutrons and gamma rays. Coconut being naturally available, it can be used readily in concrete, still maintaining almost all the qualities of the original form of concrete. Concrete obtained using coconut shell as a coarse aggregate satisfies the requirements of concrete. Coconut shell aggregate possess acceptable strength which is required for structural concrete

Occurrence and in-stream attenuation of wastewater-derived pharmaceuticals in Iberian rivers.

Science.gov (United States)

Acuña, Vicenç; von Schiller, Daniel; García-Galán, Maria Jesús; Rodríguez-Mozaz, Sara; Corominas, Lluís; Petrovic, Mira; Poch, Manel; Barceló, Damià; Sabater, Sergi

2015-01-15

A multitude of pharmaceuticals enter surface waters via discharges of wastewater treatment plants (WWTPs), and many raise environmental and health concerns. Chemical fate models predict their concentrations using estimates of mass loading, dilution and in-stream attenuation. However, current comprehension of the attenuation rates remains a limiting factor for predictive models. We assessed in-stream attenuation of 75 pharmaceuticals in 4 river segments, aiming to characterize in-stream attenuation variability among different pharmaceutical compounds, as well as among river segments differing in environmental conditions. Our study revealed that in-stream attenuation was highly variable among pharmaceuticals and river segments and that none of the considered pharmaceutical physicochemical and molecular properties proved to be relevant in determining the mean attenuation rates. Instead, the octanol-water partition coefficient (Kow) influenced the variability of rates among river segments, likely due to its effect on sorption to sediments and suspended particles, and therefore influencing the balance between the different attenuation mechanisms (biotransformation, photolysis, sorption, and volatilization). The magnitude of the measured attenuation rates urges scientists to consider them as important as dilution when aiming to predict concentrations in freshwater ecosystems. Copyright © 2014 Elsevier B.V. All rights reserved.