Loss of inducible photorepair in a frog cell line hypersensitive to solar UV light

International Nuclear Information System (INIS)

Chao, C.C.-K.

1987-01-01

The induction of enzymatic photorepair (EPR) in ICR 2A frog cells and a derived mutant cell line DRP36 hypersensitive to solar UV was studied. Using clonogenic assays, when induced wild-type cells demonstrated an 8-fold increase of EPR the mutant cells displayed a near-background level of inducible EPR. The constitutive EPR in mutant cells, however, was the same as in wild-type cells. A mixed culture of ICR 2A and DRP36 cells showed an intermediate inducible EPR depending upon the cell ratio. Inducible EPR was also detected at the DNA level in wild-type cells, but not in mutant cells. 29 refs.; 2 figs.; 2 tabs

Electron paramagnetic resonance (EPR) biodosimetry

International Nuclear Information System (INIS)

Desrosiers, Marc; Schauer, David A.

2001-01-01

Radiation-induced electron paramagnetic resonance (EPR) signals were first reported by Gordy et al. [Proc. Natl. Acad. Sci. USA 41 (1955) 983]. The application of EPR spectroscopy to ionizing radiation dosimetry was later proposed by Brady et al. [Health Phys. 15 (1968) 43]. Since that time EPR dosimetry has been applied to accident and epidemiologic dose reconstruction, radiation therapy, food irradiation, quality assurance programs and archaeological dating. Materials that have been studied include bone, tooth enamel, alanine and quartz. This review paper presents the fundamentals and applications of EPR biodosimetry. Detailed information regarding sample collection and preparation, EPR measurements, dose reconstruction, and data analysis and interpretation will be reviewed for tooth enamel. Examples of EPR biodosimetry application in accidental overexposures, radiopharmaceutical dose assessment and retrospective epidemiologic studies will also be presented

Determination of the Average Native Background and the Light-Induced EPR Signals and their Variation in the Teeth Enamel Based on Large-Scale Survey of the Population.

Science.gov (United States)

Ivannikov, Alexander I; Khailov, Artem M; Orlenko, Sergey P; Skvortsov, Valeri G; Stepanenko, Valeri F; Zhumadilov, Kassym Sh; Williams, Benjamin B; Flood, Ann B; Swartz, Harold M

2016-12-01

The aim of the study is to determine the average intensity and variation of the native background signal amplitude (NSA) and of the solar light-induced signal amplitude (LSA) in electron paramagnetic resonance (EPR) spectra of tooth enamel for different kinds of teeth and different groups of people. These values are necessary for determination of the intensity of the radiation-induced signal amplitude (RSA) by subtraction of the expected NSA and LSA from the total signal amplitude measured in L-band for in vivo EPR dosimetry. Variation of these signals should be taken into account when estimating the uncertainty of the estimated RSA. A new analysis of several hundred EPR spectra that were measured earlier at X-band in a large-scale examination of the population of the Central Russia was performed. Based on this analysis, the average values and the variation (standard deviation, SD) of the amplitude of the NSA for the teeth from different positions, as well as LSA in outer enamel of the front teeth for different population groups, were determined. To convert data acquired at X-band to values corresponding to the conditions of measurement at L-band, the experimental dependencies of the intensities of the RSA, LSA and NSA on the m.w. power, measured at both X and L-band, were analysed. For the two central upper incisors, which are mainly used in in vivo dosimetry, the mean LSA annual rate induced only in the outer side enamel and its variation were obtained as 10 ± 2 (SD = 8) mGy y -1 , the same for X- and L-bands (results are presented as the mean ± error of mean). Mean NSA in enamel and its variation for the upper incisors was calculated at 2.0 ± 0.2 (SD = 0.5) Gy, relative to the calibrated RSA dose-response to gamma radiation measured under non-power saturation conditions at X-band. Assuming the same value for L-band under non-power saturating conditions, then for in vivo measurements at L-band at 25 mW (power saturation conditions), a mean NSA and its

Understanding the dosimetric powder EPR spectrum of sucrose by identification of the stable radiation-induced radicals

International Nuclear Information System (INIS)

Vrielinck, H.; Vanhaelewyn, G.; Matthys, P.; Callens, F.; Kusakovskij, J.

2014-01-01

Sucrose, the main component of table sugar, present in nearly every household and quite radiation sensitive, is considered as an interesting emergency dosemeter. Another application of radiation-induced radicals in sugars is the detection of irradiation in sugar-containing foodstuffs. The complexity of electron paramagnetic resonance (EPR) spectra of radicals in these materials, as a result of many hyperfine interactions and the multi-compositeness of the spectra of individual sugars, complicate dose assessment and the improvement of protocols for control and identification of irradiated sugar-containing foodstuffs using EPR. A thorough understanding of the EPR spectrum of individual irradiated sugars is desirable when one wants to reliably use them in a wide variety of dosimetric applications. Recently, the dominant room temperature stable radicals in irradiated sucrose have been thoroughly characterised using EPR, electron nuclear double resonance (ENDOR) and ENDOR-induced EPR. These radicals were structurally identified by comparing their proton hyperfine and g-tensors with the results of Density Functional Theory calculations for test radical structures. In this paper, the authors use the spin Hamiltonian parameters determined in these studies to simulate powder EPR spectra at the standard X-band (9.5 GHz), commonly used in applications, and at higher frequencies, up to J-band (285 GHz), rendering spectra with higher resolution. A few pitfalls in the simulation process are highlighted. The results indicate that the major part of the dosimetric spectrum can be understood in terms of three dominant radicals, but as-yet unidentified radicals also contribute in a non-negligible way. (authors)

Modern light-water reactors - EPR and SWR 1000. Present status and possibilities of development and application

International Nuclear Information System (INIS)

Brettschuh, W.; Schneider, D.

2001-01-01

A number of reactor concepts are being advanced worldwide also in the light of long-term perspectives in the power economy. Activities in this respect are concentrated on the proven technologies of light-water and heavy-water reactors and on gas or liquid-metal cooled designs. Also smaller units are being considered for various applications. Framatome ANP focus on further development of the EPR and SWR 1000 light-water reactor lines. These plant concepts, which were developed in cooperation with, and with the support of, power utilities together with a number of European partners, are characterized by an even higher level of safety, especially as far as potential accidental releases are concerned, and by their competitiveness in the electricity generating market compared to other sources of energy. Given the cost structure of these plants, with approx. 60% capital costs, approx. 24% operating costs, and approx. 16% fuel cycle costs, efforts are made in particular to reduce the dominating capital cost share. For the EPR, this is to be achieved by high plant capacities, i.e. lower specific capital outlays per kilowatt installed; for the SWR 1000, mainly by means of an optimized, streamlined plant design. Moreover, installed nuclear generating capacities provide long-term assurance in calculating electricity generating costs, as they are less sensitive to the variable costs of the fuel cycle and of operation than fossil-fired plants. Commercial maturity of the SWR 1000 will be achieved after the completion of basic development in late 1999 and the ongoing detailed design steps in 2001. Also for the EPR, commercial maturity has been achieved with the completion of the basic design phase. (orig.) [de

Detection of Redox Imbalance in Normal Lymphocytes with Induced Mitochondrial Dysfunction - EPR Study.

Science.gov (United States)

Georgieva, Ekaterina; Zhelev, Zhivko; Aoki, Ichio; Bakalova, Rumiana; Higashi, Tatsuya

2016-10-01

The present study describes a new approach for direct imaging of redox status in live cells using paramagnetic spin-probes, which allows evaluation of the level of oxidative stress due to overproduction of superoxide. The method is based on redox cycling of cell/mitochondria-penetrating nitroxide radicals (e.g. mito-TEMPO) and their electron-paramagnetic resonance (EPR) contrast, which makes them useful molecular sensors for analysis of redox status and oxidative stress in cells and tissues. Oxidative stress was induced in normal human lymphocytes by treatment with 2-methoxyestradiol and rotenone (ME/Rot) at different concentrations. This combination provokes mitochondrial dysfunction, which is accompanied by overproduction of superoxide. The EPR measurements were performed in dynamics on X-Band spectrometer after addition of mito-TEMPO to cell suspensions. The intensity of the EPR signal in untreated cells decreased significantly, which indicates a conversion of paramagnetic mito-TEMPO to its non-contrast diamagnetic form (hydroxylamine - mito-TEMPOH) due to reduction. In ME/Rot-treated cells, the signal decreased more slowly and to a lower level with increasing the concentration of ME/Rot. These data indicate an induction of oxidative stress in the cells in a concentration-dependent manner. A very good positive correlation between the intensity of EPR signal of mito-TEMPO and the intracellular level of superoxide was found, analyzed by conventional dihydroethidium test (R=0.9143, pEPR imaging of the superoxide level in live cells, as well as for EPR imaging of mitochondrial dysfunction and metabolic activity, accompanied by superoxide imbalance. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

Visible light-induced OH radicals in Ga2O3: an EPR study.

Science.gov (United States)

Tzitrinovich, Zeev; Lipovsky, Anat; Gedanken, Aharon; Lubart, Rachel

2013-08-21

Reactive oxygen species (ROS) were found to exist in water suspensions of several metal oxide nanoparticles (NPs), such as CuO, TiO2 and ZnO. Visible light irradiation enhanced the capability of TiO2 and ZnO NPs to generate ROS, thus increasing their antibacterial effects. Because of the possible toxic effects on the host tissue it is desired to find nano-metal oxides which do not produce ROS under room light, but only upon a strong external stimulus. Using the technique of electron-spin resonance (ESR) coupled with spin trapping, we examined the ability of Ga2O3 submicron-particle suspensions in water to produce reactive oxygen species with and without visible light irradiation. We found that in contrast to ZnO and TiO2 NPs, no ROS are produced by Ga2O3 under room light. Nevertheless blue light induced hydroxyl radical formation in Ga2O3. This finding might suggest that NPs of Ga2O3 could be used safely for infected skin sterilization.

EPR dosimetry with tooth enamel: A review

International Nuclear Information System (INIS)

Fattibene, Paola; Callens, Freddy

2010-01-01

When tooth enamel is exposed to ionizing radiation, radicals are formed, which can be detected using electron paramagnetic resonance (EPR) techniques. EPR dosimetry using tooth enamel is based on the (presumed) correlation between the intensity or amplitude of some of the radiation-induced signals with the dose absorbed in the enamel. In the present paper a critical review is given of this widely applied dosimetric method. The first part of the paper is fairly fundamental and deals with the main properties of tooth enamel and some of its model systems (e.g., synthetic apatites). Considerable attention is also paid to the numerous radiation-induced and native EPR signals and the radicals responsible for them. The relevant methods for EPR detection, identification and spectrum analyzing are reviewed from a general point of view. Finally, the needs for solid-state modelling and studies of the linearity of the dose response are investigated. The second part is devoted to the practical implementation of EPR dosimetry using enamel. It concerns specific problems of preparation of samples, their irradiation and spectrum acquisition. It also describes how the dosimetric signal intensity and dose can be retrieved from the EPR spectra. Special attention is paid to the energy dependence of the EPR response and to sources of uncertainties. Results of and problems encountered in international intercomparisons and epidemiological studies are also dealt with. In the final section the future of EPR dosimetry with tooth enamel is analyzed.

EPR compared to international requirements (Mainly EUR)

International Nuclear Information System (INIS)

Broecker, B.

1996-01-01

A number of European Utilities have entered an agreement to write common requirements dedicated to future light water nuclear power plants to be built in Europe. The activities are known under the sign EUR (European Utilities Requirements). EPR, the future European Pressurized water Reactor, is the first installation of this type which will be operational from the year 2000 onwards, must fulfill the European requirements. EPR will serve as a test whether these requirements are realistic and well balanced. At the basic design stage of EPR, this paper concentrates on four main topics: the requirements which are new compared with existing reactors and which put a major challenge to the designer; the requirements today still open and the way they can be met by the EPR or not; the points for which already today the EPR special requirements exceed the EUR; the examples where the design of the EPR has given feedback which has led to a change of the EUR. EPR and EUR are different approaches to the reactor of the future. EUR is a set of requirements which leaves a flexibility to the designer while EPR is a real project which defines the technical solutions. EPR will fulfill the EUR and will at the same time serve as a test whether these requirements are realistic. EPR will also fulfill international requirements with minor changes. (J.S.). 7 figs

EPR meeting international safety standards with margin

International Nuclear Information System (INIS)

Mazurkiewicz, S.M.; Brauns, J.; Blombach, J.

2005-01-01

The EPR provides technology that offers a solution to the market's need for safe, economic power. The EPR was originally developed through a joint effort between Framatome ANP and Siemens by incorporating the best technological features from the French and German nuclear reactor fleets into a cost-competitive product capable of international licensing. As such, the EPR is a global product with commercial units currently being built in Finland at the Olkiluoto site, and planned for France, at the Flamanville site. Framatome ANP has recently proposed four EPR units to China in response to a request for vendor bids. In addition, Framatome ANP has announced their intent to pursue design certification with the United States Nuclear Regulatory Commission (NRC). This paper discusses how EPR's innovative safety philosophy ensures compliance with international safety standards for advanced light-water reactors (ALWRs). (author)

EPR meeting international safety standards with margin

International Nuclear Information System (INIS)

Mazurkiewicz, S.M.; Brauns, J.; Blombach, J.

2005-01-01

The EPR provides technology that offers a solution to the market's need for safe, economic power. The EPR was originally developed through a joint effort between Framatome ANP and Siemens by incorporating the best technological features from the French and German nuclear reactor fleets into a cost-competitive product capable of international licensing. As such, the EPR is a global product with commercial units currently being built in Finland at the Olkiluoto site, and planned for France, at the Flamanville site. Framatome ANP has recently proposed four EPR units to China in response to a request for vendor bids. In addition, Framatome ANP has announced their intent to pursue design certification in with the United States Nuclear Regulatory Commission (NRC). This paper discusses how EPR's innovative safety philosophy ensures compliance with international safety standards for advanced light-water reactors (ALWRs). (author)

EPR study of N+-ion-induced free radical formation in antibiotic-producers

International Nuclear Information System (INIS)

Xie Liqing; Zhang Yinfen; Chen Ruyi; Gao Juncheng; Zhang Peiling; Ying Hengfeng.

1995-01-01

Under the room temperature, electron paramagnetic resonance (EPR) spectrometer was used to study free radical formation in antibiotic-producers in order to investigate antibiotic-producer mutagenic breeding, which were induced by N + ion implanting into antibiotic-producers (e.g., Streptomyces ribosidificus, Streptomyces kanamyceticus and the phage-resistant culture of Streptomyces kanamyceticus). The results show that a lot of free radicals can be induced by N + ion implanting into antibiotic-producers, and the yields of the free radicals increase with implanting dose. The death rate of antibiotic-producers rises due to the increase of N + -ion-induced free radical yields. (author)

Identification of gamma-irradiated fruit juices by EPR spectroscopy

International Nuclear Information System (INIS)

Aleksieva, K.I.; Dimov, K.G.; Yordanov, N.D.

2014-01-01

The results of electron paramagnetic resonance (EPR) study on commercially available juices from various fruits and different fruit contents: 25%, 40%, 50%, and 100%, homemade juices, nectars and concentrated fruit syrups, before and after gamma-irradiation are reported. In order to remove water from non- and irradiated samples all juices and nectars were filtered; the solid residue was washed with alcohol and dried at room temperature. Only concentrated fruit syrups were dried for 60 min at 40 °C in a standard laboratory oven. All samples under study show a singlet EPR line with g=2.0025 before irradiation with exception of concentrated fruit syrups, which are EPR silent. Irradiation of juice samples gives rise to complex EPR spectra which gradually transferred to “cellulose-like” EPR spectrum from 25% to 100% fruit content. Concentrated fruit syrups show typical “sugar-like“ spectra due to added saccharides. All EPR spectra are characteristic and can prove radiation treatment. The fading kinetics of radiation-induced EPR signals were studied for a period of 60 days after irradiation. - Highlights: • The EPR analysis of juices, nectars and syrups proves that the sample has been irradiated. • Two sample preparation procedures were used. • The stability of the radiation induced EPR signals was studied over 2 months. • Application of European standards can be extended for irradiated juices and syrups

EPR study on non- and gamma-irradiated herbal pills

Energy Technology Data Exchange (ETDEWEB)

Aleksieva, K., E-mail: katerina_bas@abv.b [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Lagunov, O. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Dimov, K. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria); Yordanov, N.D. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

2011-06-15

The results of EPR studies on herbal pills of marigold, hawthorn, yarrow, common balm, tutsan, nettle and thyme before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line with a g-factor of 2.0048{+-}0.0005. After irradiation herbal pills could be separated in two groups according to their EPR spectra. Radiation-induced free radicals in pills of marigold, yarrow, nettle, tutsan and thyme could be attributed mainly to saccharide excipients. Tablets of hawthorn and common balm show 'cellulose-like' EPR spectrum, superimposed on partly resolved carbohydrate spectrum, due to the active part (herb) and inulin, which is present in the pills as an excipient. Fading study of the radiation-induced EPR signals confirms that sugar radicals are more stable than cellulose species. The reported results show that the presence of characteristic EPR spectra of herbal pills due to excipients or active part can be used as unambiguous proof of radiation processing within 35 or more days after irradiation.

EPR study on non- and gamma-irradiated herbal pills

International Nuclear Information System (INIS)

Aleksieva, K.; Lagunov, O.; Dimov, K.; Yordanov, N.D.

2011-01-01

The results of EPR studies on herbal pills of marigold, hawthorn, yarrow, common balm, tutsan, nettle and thyme before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line with a g-factor of 2.0048±0.0005. After irradiation herbal pills could be separated in two groups according to their EPR spectra. Radiation-induced free radicals in pills of marigold, yarrow, nettle, tutsan and thyme could be attributed mainly to saccharide excipients. Tablets of hawthorn and common balm show 'cellulose-like' EPR spectrum, superimposed on partly resolved carbohydrate spectrum, due to the active part (herb) and inulin, which is present in the pills as an excipient. Fading study of the radiation-induced EPR signals confirms that sugar radicals are more stable than cellulose species. The reported results show that the presence of characteristic EPR spectra of herbal pills due to excipients or active part can be used as unambiguous proof of radiation processing within 35 or more days after irradiation.

EPR study on non- and gamma-irradiated herbal pills

Science.gov (United States)

Aleksieva, K.; Lagunov, O.; Dimov, K.; Yordanov, N. D.

2011-06-01

The results of EPR studies on herbal pills of marigold, hawthorn, yarrow, common balm, tutsan, nettle and thyme before and after gamma-irradiation are reported. Before irradiation all samples exhibit one weak singlet EPR line with a g-factor of 2.0048±0.0005. After irradiation herbal pills could be separated in two groups according to their EPR spectra. Radiation-induced free radicals in pills of marigold, yarrow, nettle, tutsan and thyme could be attributed mainly to saccharide excipients. Tablets of hawthorn and common balm show "cellulose-like" EPR spectrum, superimposed on partly resolved carbohydrate spectrum, due to the active part (herb) and inulin, which is present in the pills as an excipient. Fading study of the radiation-induced EPR signals confirms that sugar radicals are more stable than cellulose species. The reported results show that the presence of characteristic EPR spectra of herbal pills due to excipients or active part can be used as unambiguous proof of radiation processing within 35 or more days after irradiation.

EPR investigation of some gamma-irradiated medicines

International Nuclear Information System (INIS)

Aleksieva, Katerina; Yordanov, Nicola

2016-01-01

The results of EPR studies on three medical tablets – Galanthamine, Cytisine and Tribulus terrestris before and after gamma-irradiation are reported. Before irradiation Galanthamine and Cytisine tablets are EPR silent, whereas Tribulus terrestris show a broad singlet line with g factor 2.2084±0.002. The same spectrum is recorded after irradiation. After gamma-sterilization, however, Galanthamine and Cytisine tablets exhibit a typical EPR spectrum due to gamma induced free radicals in lactose used as an excipient. These stable free radicals can be used for identification of radiation processing for a long time after it. Key words: medical tablets, gamma-irradiation, EPR

Chemistry of artemisinin: an EPR study and nucleobases interaction

International Nuclear Information System (INIS)

Mustafa, Damra Elhaj

2000-10-01

In the present, the radical transformations of artemisinin, a potent antimalarial drug have been examined using EPR and EPR spin trapping techniques. The effect of light on artemisinin has been investigated at 77 K as well as with the use of phenyl butyl nitrone (PBN) spin trapping agent. While no EPR signal was observed at 77 K, intense light irradiation of artemisinin/PBN gave EPR signal characteristic of radical transformation of the PBN. The reactions of artemisinin with iron (II), manganese (II), hemin and ferrocyanide ion have been investigated by spin trapping techniques. Artemisinin/iron (II) formed spin adducts with nitrosobenzene, nitroso-t-butane and PBN. The hypertine splittings of the spin adducts were a N =1.08 mT/a N =1.25 mT/a N =0.09 mT and a N =1.56 mT/a N =0.29 mT respectively. PBN trapping of artemether/iron (II) gave similar result to artemisinin/iron (II). These results are indicative of secondary carbon-centered radical formation. While artemisinin/hemin/PBN gave very weak EPR signal, ferrocyanide under the same condition gave no signal. Incubation of artemisinin with RNA at different reaction conditions, including irradiation with light, heat and mild acidic media, revealed no RNA damage when examined by agarose electrophoresis. However, artemisinin/iron (II) caused RNA damage in pH-dependant manner. In contrast, hemin did not show the same effect when it was used instead of iron (II). (Author)

The EPR reactor

International Nuclear Information System (INIS)

Lacoste, A.C.; Dupuy, Ph.; Gupta, O.; Perez, J.R.; Emond, D.; Cererino, G.; Rousseau, J.M.; Jeffroy, F.; Evrard, J.M.; Seiler, J.M.; Azarian, G.; Chaumont, B.; Dubail, A.; Fischer, M.; Tiippana, P.; Hyvarinen, J.; Zaleski, C.P.; Meritet, S.; Iglesias, F.; Vincent, C.; Massart, S.; Graillat, G.; Esteve, B.; Mansillon, Y.; Gatinol, C.; Carre, F.

2005-01-01

This document reviews economical and environmental aspects of the EPR project. The following topics are discussed: role and point of view of the French Nuclear Safety Authority on EPR, control of design and manufacturing of EPR by the French Nuclear Safety Authority, assessment by IRSN of EPR safety, research and development in support of EPR, STUK safety review of EPR design, standpoint on EPR, the place of EPR in the French energy policy, the place of EPR in EDF strategy, EPR spearhead of nuclear rebirth, the public debate, the local stakes concerning the building of EPR in France at Flamanville (Manche) and the research on fourth generation reactors. (A.L.B.)

EPR of radiation defects in lithium-oxyfluoride glass ceramics

Energy Technology Data Exchange (ETDEWEB)

Fedotovs, A; Rogulis, U; Sarakovskis, A; Dimitrocenko, L, E-mail: andris-f@navigator.l [Institute of Solid State Physics, University of Latvia, Kengaraga st. 8, LV-1063, Riga (Latvia)

2010-11-01

We studied oxyfluoride composites based on lithium silicate glasses with yttrium fluorides and rare-earth dopants. The electron paramagnetic resonance (EPR) has been used to obtain information about radiation induced defects in these materials. Spectra have been measured before and after X-ray irradiation at room temperature and at liquid nitrogen temperature. Fluoride crystallites within samples were created by means of thermal treatment at specific temperatures. EPR spectra of radiation induced defects in oxyfluoride glass ceramics, in which crystallites have not been yet created, show no explicit hfs interaction of fluorine nuclei. However, in glass ceramics, which already contains fluoride crystallites, the hfs characteristic to fluorine nuclei appears in the EPR spectra. EPR hyperfine structure could be explained within a model of an F-type centre in YF{sub 3} crystalline phase.

EPR of radiation defects in lithium-oxyfluoride glass ceramics

Science.gov (United States)

Fedotovs, A.; Rogulis, U.; Sarakovskis, A.; Dimitrocenko, L.

2010-11-01

We studied oxyfluoride composites based on lithium silicate glasses with yttrium fluorides and rare-earth dopants. The electron paramagnetic resonance (EPR) has been used to obtain information about radiation induced defects in these materials. Spectra have been measured before and after X-ray irradiation at room temperature and at liquid nitrogen temperature. Fluoride crystallites within samples were created by means of thermal treatment at specific temperatures. EPR spectra of radiation induced defects in oxyfluoride glass ceramics, in which crystallites have not been yet created, show no explicit hfs interaction of fluorine nuclei. However, in glass ceramics, which already contains fluoride crystallites, the hfs characteristic to fluorine nuclei appears in the EPR spectra. EPR hyperfine structure could be explained within a model of an F-type centre in YF3 crystalline phase.

Chemistry of artemisinin: an EPR study and nucleobases interaction

Energy Technology Data Exchange (ETDEWEB)

Mustafa, Damra Elhaj [Department of Chemistry, Faculty of Education, University of Khartoum, Khartoum (Sudan)

2000-10-01

In the present, the radical transformations of artemisinin, a potent antimalarial drug have been examined using EPR and EPR spin trapping techniques. The effect of light on artemisinin has been investigated at 77 K as well as with the use of phenyl butyl nitrone (PBN) spin trapping agent. While no EPR signal was observed at 77 K, intense light irradiation of artemisinin/PBN gave EPR signal characteristic of radical transformation of the PBN. The reactions of artemisinin with iron (II), manganese (II), hemin and ferrocyanide ion have been investigated by spin trapping techniques. Artemisinin/iron (II) formed spin adducts with nitrosobenzene, nitroso-t-butane and PBN. The hypertine splittings of the spin adducts were a{sub N}=1.08 mT/a{sub N}=1.25 mT/a{sub N}=0.09 mT and a{sub N}=1.56 mT/a{sub N}=0.29 mT respectively. PBN trapping of artemether/iron (II) gave similar result to artemisinin/iron (II). These results are indicative of secondary carbon-centered radical formation. While artemisinin/hemin/PBN gave very weak EPR signal, ferrocyanide under the same condition gave no signal. Incubation of artemisinin with RNA at different reaction conditions, including irradiation with light, heat and mild acidic media, revealed no RNA damage when examined by agarose electrophoresis. However, artemisinin/iron (II) caused RNA damage in pH-dependant manner. In contrast, hemin did not show the same effect when it was used instead of iron (II). (Author)

X- and Q-band EPR studies on fine powders of irradiated plants. New approach for detection of their radiation history by using Q-band EPR spectrometry

International Nuclear Information System (INIS)

Yordanov, Nicola D.; Aleksieva, Katerina

2004-01-01

X- and Q-band EPR studies after γ-irradiation of some dry spices and aromatic herbs are reported. Before irradiation all samples show only one singlet line in X-band EPR, whereas the Q-band EPR spectrum of the same samples is a superposition of two individual spectra--one corresponding to the above EPR signal, with an anisotropic spectrum, and a second one consisting of six lines due to the Mn 2+ naturally present in plants. The radiation induced EPR signal due to cellulose free radicals was not detected after γ-irradiation, but only the increase of the natural signal present before the irradiation. The fading kinetic of this EPR signal was monitored in three cases--when samples were kept in plastic bags without any special conditioning after irradiation, when samples were covered with paraffin before irradiation and when samples were dried at 60 deg. C for 1 h before irradiation. The studies show that stability of radiation induced EPR signals decreases in the order of: paraffin covered > heated before irradiation > kept at room conditions. The two EPR spectra in the Q-band--one with radiation dependent intensity and a second due to Mn 2+ , which is radiation independent allow identification of previous radiation treatment based on the fact that Mn 2+ quantity in the sample is constant whereas the quantity of radiation-induced free radicals is temperature dependent. It was found that for irradiated samples the ratio between EPR intensity of the free radicals and that of Mn 2+ before and after heating decreases with 50-60% whereas for non-irradiated samples it is ca. 10-15%

EPR of gamma irradiated solid sucrose and UV spectra of its solution. An attempt for calibration of solid state/EPR dosimetry

International Nuclear Information System (INIS)

Yordanov, N.D.; Karakirova, Y.

2007-01-01

A simple new approach for independent calibration of solid state/EPR (SS/EPR) dosimetry system is reported. It is based on the fact that: (i) gamma-irradiation of solid sucrose (sugar) induces stable EPR detectable free radicals accompanied by UV detectable brown colour stable in the solid state and in solution; (ii) both the EPR intensity of gamma-irradiated solid sucrose and its solution UV absorbance linearly depend on the absorbed dose high energy radiation and may be independently used for dosimetric purpose; (iii) UV spectrometers are calibrated. The correlation between EPR response and absorbed dose radiation of solid sucrose and UV absorption of its solutions is used in the present communication for calibration purpose. The procedure of sucrose extraction from sucrose-paraffin dosimeters is described. The calibration procedure may be applied to any other (alanine, self-calibrated, etc.) SS/EPR dosimeters, simultaneously irradiated with sucrose

One-way EPR steering and genuine multipartite EPR steering

Science.gov (United States)

He, Qiongyi; Reid, Margaret D.

2012-11-01

We propose criteria and experimental strategies to realise the Einstein-Podolsky-Rosen (EPR) steering nonlocality. One-way steering can be obtained where there is asymmetry of thermal noise on each system. We also present EPR steering inequalities that act as signatures and suggest how to optimise EPR correlations in specific schemes so that the genuine multipartite EPR steering nonlocality (EPR paradox) can also possibly be realised. The results presented here also apply to the spatially separated macroscopic atomic ensembles.

Properties of the ammonium tartrate/EPR dosimeter

International Nuclear Information System (INIS)

Yordanov, N.D.; Gancheva, V.

2004-01-01

The EPR response of γ-irradiated ammonium tartrate on the absorbed dose of γ-rays up to 22 kGy as well as the changes in the shape of the EPR spectrum upon applied modulation amplitude and microwave power are reported. Also the possibility to use ammonium tartrate together with Mn 2+ magnetically diluted in MgO as an internal reference material is evaluated. The influence of the microwave power and the modulation amplitude on their dose response is investigated. The results show that the radiation-induced EPR spectrum of ammonium tartrate, obtained at a low microwave power is complex consisting several patterns and is more easily saturated than the Mn 2+ EPR spectrum. In this case the following settings of the EPR parameters are recommended: H mod ≤0.05 mT and 10≤P MW ≤13 mW. Using these parameters the dosimeters can be considered for use in intercomparisons

EPR detection of foods preserved with ionizing radiation

Science.gov (United States)

Stachowicz, W.; Burlinska, G.; Michalik, J.

1998-06-01

The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ( 60Co) and 10 MeV electrons were observed

EPR detection of foods preserved with ionizing radiation

International Nuclear Information System (INIS)

Stachowicz, W.; Burlinska, G.; Michalik, J.

1998-01-01

The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to the beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ( 60 Co) and 10 MeV electrons were observed

EPR detection of foods preserved with ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Stachowicz, W.; Burlinska, G.; Michalik, J

1998-06-01

The applicability of the epr technique for the detection of dried vegetables, mushrooms, some spices, flavour additives and some condiments preserved with ionizing radiation is discussed. The epr signals recorded after exposure to gamma rays and to the beams of 10 MeV electrons from linac are stable, intense and specific enough as compared with those observed with nonirradiated samples and could be used for the detection of irradiation. However, stability of radiation induced epr signals produced in these foods depends on storage condition. No differences in shapes (spectral parameters) and intensities of the epr spectra recorded with samples exposed to the same doses of gamma rays ({sup 60}Co) and 10 MeV electrons were observed.

Applications of EPR in radiation research

CERN Document Server

Lund, Anders

2014-01-01

Applications of EPR in Radiation Research is a multi-author contributed volume presented in eight themes: I. Elementary radiation processes (in situ and low temperature radiolysis, quantum solids); II: Solid state radiation chemistry (crystalline, amorphous and heterogeneous systems); III: Biochemistry, biophysics and biology applications (radicals in biomaterials, spin trapping, free-radical-induced DNA damage); IV: Materials science (polymeric and electronic materials, materials for treatment of nuclear waste, irradiated food); V: Radiation metrology (EPR-dosimetry, retrospective and medical

Echo detected EPR as a tool for detecting radiation-induced defect signals in pottery

International Nuclear Information System (INIS)

Zoleo, Alfonso; Bortolussi, Claudia; Brustolon, Marina

2011-01-01

Archaeological fragments of pottery have been investigated by using CW-EPR and Echo Detected EPR (EDEPR). EDEPR allows to remove the CW-EPR dominant Fe(III) background spectrum, hiding much weaker signals potentially useful for dating purpose. EDEPR spectra attributed to a methyl radical and to feldspar defects have been recorded at room and low temperature for an Iron Age cooking ware (700 B.C.). A study on the dependence of EDEPR intensity over absorbed dose on a series of γ-irradiated brick samples (estimated age of 562 ± 140 B.C.) has confirmed the potential efficacy of the proposed method for spotting defect signals out of the strong iron background. - Highlights: → Fe(III) CW-EPR signals cover CW-EPR-detectable defects in ceramics. → Echo detected EPR gets rid of Fe(III) signals, disclosing defect signals. → Echo detected EPR detects defect signals even at relatively low doses.

Selective saturation method for EPR dosimetry with tooth enamel

International Nuclear Information System (INIS)

Ignatiev, E.A.; Romanyukha, A.A.; Koshta, A.A.; Wieser, A.

1996-01-01

The method of selective saturation is based on the difference in the microwave (mw) power dependence of the background and radiation induced EPR components of the tooth enamel spectrum. The subtraction of the EPR spectrum recorded at low mw power from that recorded at higher mw power provides a considerable reduction of the background component in the spectrum. The resolution of the EPR spectrum could be improved 10-fold, however simultaneously the signal-to-noise ratio was found to be reduced twice. A detailed comparative study of reference samples with known absorbed doses was performed to demonstrate the advantage of the method. The application of the selective saturation method for EPR dosimetry with tooth enamel reduced the lower limit of EPR dosimetry to about 100 mGy. (author)

Comparative study of some new EPR dosimeters

International Nuclear Information System (INIS)

Alzimami, K.S.; Maghraby, Ahmed M.; Bradley, D.A.

2014-01-01

Investigations have been made of four new radiation dosimetry EPR candidates from the same family of materials: sulfamic acid, sulfanillic acid, homotaurine, and taurine. Mass energy attenuation coefficients, mass stopping power values and the time dependence of the radiation induced radicals are compared. Also investigated are the microwave saturation behavior and the effect of applied modulation amplitude on both peak-to-peak line width (W PP ) and peak-to-peak signal height (H PP ). The dosimeters are characterized by simple spectra and stable radiation-induced radicals over reasonable durations, especially in taurine dosimeters. Sulfamic acid dosimeters possessed the highest sensitivity followed by taurine and homotaurine and sulfanillic. - Highlights: ► Several EPR dosimeters were suggested based on SO 3 − radical. ► Taurine, homotaurine, sulfanilic, and sulfamic acid all possess simple EPR spectra. ► Dosimeters were compared to each other in terms of the dosimetric point of view. ► Energy dependence curves of the selected dosimeters were compared to eachother

Identification of gamma-irradiated fruit juices by EPR spectroscopy

Science.gov (United States)

Aleksieva, K. I.; Dimov, K. G.; Yordanov, N. D.

2014-10-01

The results of electron paramagnetic resonance (EPR) study on commercially available juices from various fruits and different fruit contents: 25%, 40%, 50%, and 100%, homemade juices, nectars and concentrated fruit syrups, before and after gamma-irradiation are reported. In order to remove water from non- and irradiated samples all juices and nectars were filtered; the solid residue was washed with alcohol and dried at room temperature. Only concentrated fruit syrups were dried for 60 min at 40 °C in a standard laboratory oven. All samples under study show a singlet EPR line with g=2.0025 before irradiation with exception of concentrated fruit syrups, which are EPR silent. Irradiation of juice samples gives rise to complex EPR spectra which gradually transferred to "cellulose-like" EPR spectrum from 25% to 100% fruit content. Concentrated fruit syrups show typical "sugar-like" spectra due to added saccharides. All EPR spectra are characteristic and can prove radiation treatment. The fading kinetics of radiation-induced EPR signals were studied for a period of 60 days after irradiation.

EPR study on tomatoes before and after gamma-irradiation

International Nuclear Information System (INIS)

Aleksieva, K.; Georgieva, L.; Tzvetkova, E.; Yordanov, N.D.

2009-01-01

The results from the EPR studies on fresh, air-dried and lyophilized tomato samples before and after gamma-irradiation are reported. Before irradiation fresh and air-dried tomatoes exhibit one singlet EPR line characterized with common g-factor of 2.0048±0.0005, whereas freeze-dried tomato does not show any EPR spectrum. After irradiation, a typical 'cellulose-like' triplet EPR spectrum appears in all samples, attributed to cellulose free radicals, generated by gamma-irradiation. It consists of intense central line with g=2.0048±0.0005 and two weak satellite lines separated ca. 3 mT left and right of it. In air-dried and lyophilized tomatoes the 'cellulose-like' EPR spectrum is superimposed by an additional partly resolved carbohydrate spectrum. Fading measurements of the radiation-induced EPR signals indicate that the intensity of the EPR spectra of air-dried and freeze-dried tomato are reduced to about 50% after 50 days, whereas those of fresh irradiated tomatoes kept at 4 o C fade completely in 15 days. The reported results unambiguously show that the presence of two satellite lines in the EPR 'cellulose-like' spectra of tomato samples can be used for identification of radiation processing.

Factors influencing EPR dosimetry in fingernails

International Nuclear Information System (INIS)

Dubner, D.L.; Spinella, M.R.; Bof, E.

2010-01-01

The technique based on the detection of ionizing radiation induced radicals by EPR in tooth enamel is an established method for the dosimetry of exposed persons in radiological emergencies. Dosimetry based on EPR spectral analysis of fingernail clippings, currently under development, has the practical advantage of the easier sample collection. A limiting factor is that overlapping the radiation induced signal (RIS), fingernails have shown the presence of two mechanically induced signals, called MIS1 and MIS2, due to elastic and plastic deformation respectively, at the time of fingernails cutting. With a water treatment, MIS1 is eliminated while MIS2 is considerably reduced. The calibration curves needed for radiation accident dosimetry should have 'universal' characteristics, ie. Represent the variability that can be found in different individuals. Early studies were directed to the analysis of factors affecting the development of such universal calibration curves. The peak to peak amplitude of the signal before and after the water treatment as well as the effect of size and number of clippings were studied. Furthermore, the interpersonal and intrapersonal variability were analyzed. Taking into account these previous studies, the optimal conditions for measurement were determined and EPR spectra of samples irradiated at different doses were used for the developing of dose-response curves. This paper presents the analysis of the results.(authors) [es

Software for evaluation of EPR-dosimetry performance

International Nuclear Information System (INIS)

Shishkina, E.A.; Timofeev, Yu.S.; Ivanov, D.V.

2014-01-01

Electron paramagnetic resonance (EPR) with tooth enamel is a method extensively used for retrospective external dosimetry. Different research groups apply different equipment, sample preparation procedures and spectrum processing algorithms for EPR dosimetry. A uniform algorithm for description and comparison of performances was designed and implemented in a new computer code. The aim of the paper is to introduce the new software 'EPR-dosimetry performance'. The computer code is a user-friendly tool for providing a full description of method-specific capabilities of EPR tooth dosimetry, from metrological characteristics to practical limitations in applications. The software designed for scientists and engineers has several applications, including support of method calibration by evaluation of calibration parameters, evaluation of critical value and detection limit for registration of radiation-induced signal amplitude, estimation of critical value and detection limit for dose evaluation, estimation of minimal detectable value for anthropogenic dose assessment and description of method uncertainty. (authors)

Kinetics of the radicals induced in gamma irradiated sulfafurazole: an EPR study

International Nuclear Information System (INIS)

Colak, S.; Korkmaz, M.

2004-01-01

The spectroscopic and kinetic features of the radiolytic intermediates produced in gamma irradiated sulfafurazole (SFZ) were investigated at different temperatures in the dose range 5-50 kGy using EPR and IR techniques. The imodiation produced two species (A, B) in SFZ. The heights of the peaks were used to monitor the temperature, time dependent and kinetic features of the radical species contributing to the EPR spectrum. The applicability of EPR technique for monitoring radiosterilization of SFZ is discussed. The radiation yield of solid SFZ was found to be very low (G=0.16), and basing on this it was concluded that SFZ and SFZ containing drugs can be safely sterilized by radiation. The EPR data were used to characterize the contributing radicals produced in gamma irradiated SFZ. No definite difference was observed between unirradiated and irradiated IR spectra of SFZ. (orig.)

Limits in EPR dosimetry for irradiated dried fruits discrimination

International Nuclear Information System (INIS)

Brasoveanu, Mirela M. E-mirela@alpha.infim.ro; Nemtanu, R.; Minea, R.; Grecu, V.V.

2003-01-01

Irradiation of food induces free radical species. EPR dosimetry in irradiated goods puts in evidence if these radicals are stable in environmental condition. Irradiation of dried fruits has been carried out. Their behaviour under irradiation was investigated and correlation between EPR signal and irradiation dose was determined. Electrons of 6 MeV (mean energy) and doses up to 10 kGy were used. EPR spectra were recorded with a Jeol spectrometer, JES-ME-3X tip, with a 100 kHz modulation. The dried fruits can be separated into categories depending on the EPR signal intensity. Strong signals are observed in those fruits in which possible crystalline-like phases exist. As the amount of crystallized sugar decreases, the EPR signals become weaker. Dependencies on irradiation dose give a linear correlation below 10 kGy. The spectra are compared to irradiated sugar and differences and similarities are discussed. (authors)

Alcoholic extraction enables EPR analysis to characterize radiation-induced cellulosic signals in spices.

Science.gov (United States)

Ahn, Jae-Jun; Sanyal, Bhaskar; Akram, Kashif; Kwon, Joong-Ho

2014-11-19

Different spices such as turmeric, oregano, and cinnamon were γ-irradiated at 1 and 10 kGy. The electron paramagnetic resonance (EPR) spectra of the nonirradiated samples were characterized by a single central signal (g = 2.006), the intensity of which was significantly enhanced upon irradiation. The EPR spectra of the irradiated spice samples were characterized by an additional triplet signal at g = 2.006 with a hyperfine coupling constant of 3 mT, associated with the cellulose radical. EPR analysis on various sample pretreatments in the irradiated spice samples demonstrated that the spectral features of the cellulose radical varied on the basis of the pretreatment protocol. Alcoholic extraction pretreatment produced considerable improvements of the EPR signals of the irradiated spice samples relative to the conventional oven and freeze-drying techniques. The alcoholic extraction process is therefore proposed as the most suitable sample pretreatment for unambiguous detection of irradiated spices by EPR spectroscopy.

TL and EPR dating: some applications

Energy Technology Data Exchange (ETDEWEB)

Watanabe, S. [Institute of Physics, University of Sao Paulo, Sao Paulo (Brazil)

2006-07-01

The intensity of thermoluminescence light emitted by a crystal is a function of radiation dose. The number of defects or of radicals in a crystal or organic substances is also a function of radiation dose. Since such defects or radicals present EPR signals, the EPR intensity is also a function of radiation dose. These facts are basis for radiation dosimetry and can be applied in dating of archaeological potteries or other materials, as well as in dating geological substances such as sediments, caves speleothemes, animal teeth and bones. Recent investigation on sensitized quartz based dosimeters and dating calcite covering ancient wall painting to find early settlers in Brazil will be presented. (Author)

Nuclear choice. Towards the EPR with mincing steps

International Nuclear Information System (INIS)

Jemain, A.

2003-01-01

The French government is on the way to give its green light for the construction of the EPR (European Pressurized water Reactor), the 1600 MWe demonstrator reactor of third generation of Framatome ANP (Areva). Fifty seven months will be necessary for its construction which, with the public inquiry, would lead to a first commissioning by 2010. This reactor will progressively renew the present day park between 2015-2020. The EPR project will cost 3 billions of euros but the financing remains to be found. Short paper. (J.S.)

Can EPR non-locality be geometrical?

International Nuclear Information System (INIS)

Ne'eman, Y.

1995-01-01

The presence in Quantum Mechanics of non-local correlations is one of the two fundamentally non-intuitive features of that theory. The non-local correlations themselves fall into two classes: EPR and Geometrical. The non-local characteristics of the geometrical type are well-understood and are not suspected of possibly generating acausal features, such as faster-than-light propagation of information. This has especially become true since the emergence of a geometrical treatment for the relevant gauge theories, i.e. Fiber Bundle geometry, in which the quantum non-localities are seen to correspond to pure homotopy considerations. This aspect is reviewed in section 2. Contrary-wise, from its very conception, the EPR situation was felt to be paradoxical. It has been suggested that the non-local features of EPR might also derive from geometrical considerations, like all other non-local characteristics of QM. In[7], one of the authors was able to point out several plausibility arguments for this thesis, emphasizing in particular similarities between the non-local correlations provided by any gauge field theory and those required by the preservation of the quantum numbers of the original EPR state-vector, throughout its spatially-extended mode. The derivation was, however, somewhat incomplete, especially because of the apparent difference between, on the one hand, the closed spatial loops arising in the analysis of the geometrical non-localities, from Aharonov-Bohm and Berry phases to magnetic monopoles and instantons, and on the other hand, in the EPR case, the open line drawn by the positions of the two moving decay products of the disintegrating particle. In what follows, the authors endeavor to remove this obstacle and show that as in all other QM non-localities, EPR is somehow related to closed loops, almost involving homotopy considerations. They develop this view in section 3

A technique to measure the absorbed dose in human tooth enamel using EPR method

International Nuclear Information System (INIS)

Lanjanian, H.; Ziaie, F.; Modarresi, M.; Nikzad, M.; Shahvar, A.; Durrani, S.A.

2008-01-01

The EPR spectrum of irradiated tooth enamel contains a multitude of signals that are divided into two categories of radiation-induced and radiation insensitive (native) signals. At lower doses the broad native signal obscures the radiation-induced signal. In this work attempt has been made to find a method to measure the radiation-induced signal other than peak-to-peak signal amplitude measurement. For this reason software was programmed to extract the data from EPR system. The average amplitude of the radiation-induced EPR signal which is defined between the known g-values can also be calculated using the software. The result of this calculations were considered as the EPR response for the tooth enamel samples irradiated from 100 to 500 mGy and was drawn as the calibration curve. The resulted data as compared to the peak-to-peak amplitude measurement method seems to be more reproducible and shows a better variation against the dose values

Saturation transfer EPR (ST-EPR) for dating biocarbonates containing large amount of Mn2+: separation of SO3- and CO2- lines and geochronology of Brazilian fish fossil

International Nuclear Information System (INIS)

Sastry, M.D.; Andrade, M.B.; Watanabe, Shigueo

2003-01-01

A method using saturation transfer EPR (ST-EPR) is shown to be feasible for detecting EPR signal of radiation-induced defects in biocarbonates containing large amount of Mn 2+ . The ST-EPR measurements conducted at room temperature on fish fossil of Brazilian origin, enabled the identification of CO 2 - and SO 3 - radical ions, by partially suppressing the intense signal from Mn 2+ when the signal are detected 90 deg. out of phase with magnetic field modulating signal and at high microwave power (50 mW). Using these signals the age of fish fossil is estimated to be (36±5) Ma

Host material induced hyperfine structure of F{sup +} centres EPR spectra in CaS

Energy Technology Data Exchange (ETDEWEB)

Seeman, Viktor, E-mail: viktor.seeman@ut.ee; Dolgov, Sergei; Maaroos, Aarne

2017-05-15

The hyperfine structure (HFS) of F{sup +} centres in CaS single crystals due to the interaction with {sup 33}S and {sup 43}Ca nuclei was observed in EPR spectra for the first time. Angular variations of the HFS were measured for rotation of magnetic field in {100} and {110} crystallographic planes. Using measured orientation-dependent EPR spectra and the EPR NMR program, the parameters of the spin Hamiltonian were determined. In case of {sup 33}S nucleus there is a strong dependence of the F{sup +} centre EPR spectrum on the quadrupole term whereas for {sup 43}Ca nucleus this dependence is insignificant.

Electronic Paramagnetic Resonance (EPR) of free radicals induced by X-rays in pyrene

International Nuclear Information System (INIS)

Moya Partiti, C.S. de.

1982-01-01

Pyrene single crystals C 16 H 10 , irradiated by X-rays, at room temperature, were studied by EPR technique, to determine free radicals formed by radiation. The angular dependence of EPR spectra was explained by the presence of two kinds of radicals with an aditional hydrogen: 2-H 2 pyrene and 3-H 2 pyrene. It was studied the isothermic decay of the EPR signal and two typical values for the activation energy were found = (1,9+-0,1) eV and (1,93+-0,03) eV. (author) [pt

New Generation of self-calibrated SS/EPR dosimeters: Alanine/EPR dosimeters

International Nuclear Information System (INIS)

Yordanov, N.D.; Gancheva, V.

1999-01-01

A new type of solid state/EPR dosimeters is described. Principally, it contains radiation sensitive diamagnetic material, some quantity of EPR active, but radiation insensitive, substance (for example Mn 2+ /MgO) and a binding material. In the present case alanine is used as a radiation sensitive substance. With this dosimeter, the EPR spectra of alanine and Mn 2+ are simultaneously recorded and the calibration graph represents the ratio of alanine versus Mn 2+ EPR signal intensity as a function of absorbed dose. In this way the reproducibility of the results is expected to be improved significantly including their intercomparison among different laboratories. Homogeneity of the prepared dosimeters and their behaviour (fading of EPR signals with time, influence of different meteorological conditions) show satisfactory reproducibility and stability with time. Because two different EPR active samples are recorded simultaneously, the influence of some instrument setting parameters (microwave power, modulation amplitude and modulation frequency) on the ratio I alanine /I Mn is also investigated. (author)

EPR and Bell Locality

OpenAIRE

Norsen, Travis

2004-01-01

A new formulation of the EPR argument is presented, one which uses John Bell's mathematically precise local causality condition in place of the looser locality assumption which was used in the original EPR paper and on which Niels Bohr seems to have based his objection to the EPR argument. The new formulation of EPR bears a striking resemblance to Bell's derivation of his famous inequalities. The relation between these two arguments -- in particular, the role of EPR as part one of Bell's two-...

Characterization of the factors having an influence on the evolution of the EPR signal of irradiated alanine

International Nuclear Information System (INIS)

Feaugas-Le-Berre, Valerie

1999-01-01

EPR/alanine dosimetry has been used by the LNHB (Laboratoire National Henri Becquerel) since many years for applied metrology. This technic is based on the measurement of the EPR signal of the free radicals induced in alanine by irradiation. The aim of this work is to characterize the factors having an influence on the evolution of the amplitude of the EPR signal of irradiated alanine to limit the uncertainties on the determination of the absorbed dose. The first step of this work has been the choice of the dosimeter. A bibliographic study completed by experiments on the response of alanine isomers to the dose and on its stability with time has lead us to choose L-α-alanine powder as dosimeter. The influence of the recording parameter of the spectrometer on the characteristics of the EPR spectrum has then been studied. This has enabled us to optimize the recording conditions of EPR spectra. As the angular anisotropy of the EPR signal limits the measurements reproducibility, an experimental protocol has been defined to solve this problem. The repeatability of the measurements has been enhanced by modifying the spectrometer and using an internal standard constituted of single crystals of CuSO 4 .5H 2 O. As the amplitude of the EPR signal is sensitive to the measurement temperature, a method of normalization of the results to 20 C has been determined. We have studied the influence of an irradiation parameter and of environmental parameters. We have shown that the EPR signal amplitude increases with irradiation temperature. The EPR signal amplitude and its evolution vary strongly with storage conditions (temperature and moisture) of the dosimeter before and after irradiation. The presence of moisture in alanine powder leads to a loss of signal amplitude. The dosimeters exposition to light also entails a loss of amplitude. Oxygen does not influence the EPR spectrum of alanine. We have noticed that the EPR signal amplitude of samples stored in absence of moisture

EPR, UV-Visible, and Near-Infrared Spectroscopic Characterization of Dolomite

Directory of Open Access Journals (Sweden)

S. Lakshmi Reddy

2008-01-01

Full Text Available Dolomite mineral samples having white and light green colors of Indian origin have been characterized by EPR, optical, and NIR spectroscopy. The optical spectrum exhibits a number of electronic bands due to presence of Fe(III ions in the mineral. From EPR studies, the parameters of g for Fe(III and g,A, and D for Mn(II are evaluated and the data confirm that the ions are in distorted octahedron. Optical absorption studies reveal that Fe(III is in distorted octahedron. The bands in NIR spectra are due to the overtones and combinations of water molecules. Thus EPR and optical absorption spectral studies have proven useful for the study of the solid state chemistry of dolomite.

Selfcalibrated alanine/EPR dosimeters. A new generation of solid state/EPR dosimeters

International Nuclear Information System (INIS)

Yordanov, N.D.; Gancheva, V.

1999-01-01

Alanine/EPR dosimeters are well established as secondary, reference dosimeters for high-energy radiation. However, there are various sources of uncertainty in the evaluation of absorbed dose. This arises primarily from the necessity to calibrate each EPR spectrometer and each batch of dosimeters before their use. In order to overcome this disadvantage, a new generation alanine/EPR dosimeter has been developed, and its possibilities as a radiation detector are reported. Principally, it is a mixture of alanine, some quantity of EPR active substance, and a binding material. The EPR active substance, acting as an internal EPR standard, is chosen to have EPR parameters which are independent of the irradiation dose. The simultaneous recording of the spectra of both the sample and the standard under the same experimental conditions and the estimation of the ratio I alanine /I Mn as a function of the absorbed dose strongly reduces the uncertainties. The response of these dosimeters for 60 Co γ-radiation exhibits excellent linearity and reproducibility in the range of absorbed dose, 10 2 - 5 x 10 4 Gy. (author)

Butanolic fraction of Moringa oleifera Lam. (Moringaceae) attenuates isoprotrenol-induced cardiac necrosis and oxidative stress in rats: an EPR study

Science.gov (United States)

Panda, Sunanda

2015-01-01

The preventive effect of Moringa oleifera polyphenolic fraction (MOPF) on cardiac damage was evaluated in isoproterenol (ISO) induced cardiotoxicity model of Wistar rats. Male rats in different groups were treated with MOPF orally at the dose of 50, 100 and 150 mg/kg/day for 28 days and were subsequently administered (s.c.) with ISO (85 mg/kg body weight) for the last two days. At the end of the experiment levels of serum troponin-T, creatine kinase-MB, lactate dehydrogenase, content of malondialdehyde (MDA), activities/levels of different cellular antioxidants were estimated in control and experimental groups. Additionally, scavenging potential to the hydroxyl radical of the fraction was measured by electron paramagnetic resonance (EPR). ISO administered rats showed significant increase in the levels of serum troponin-I, creatine kinase, lactate dehydrogenase, and heart tissue MDA content. Furthermore, marked reduction in the activities of antioxidants such as superoxide dismutase, catalase, glutathione peroxidase and reduced glutathione levels were observed. EPR study showed an increase in signal intensity in ISO-induced rats. Triphenyl tetrazolium chloride (TTC) staining of heart section revealed a marked increase in infarcted area in ISO-induced rats. Histological features of the heart also indicated a disruption in the structure of cardiac myofibrils in these animals. MOPF (100 mg/kg body weight) pretreatment prevented all these adverse effects of ISO. Present results show that the rich polyphenolic content of Moringa oleifera significantly reduced the myocardial damage and decreased the oxidative stress, possibly through hydroxyl radical scavenging activity as evidenced from the EPR spectra. PMID:26417351

Quantitative determination of charge transfer parameters of photorefractive BaTiO3:Rh from EPR-based defect studies

International Nuclear Information System (INIS)

Veber, C; Meyer, M; Schirmer, O F; Kaczmarek, M

2003-01-01

Optical absorption bands can be used as fingerprints of defects and their charge states in insulators and semiconductors. On the basis of the photochromicity usually shown by such materials, a method is introduced by which the optical bands are assigned to the defects and their charge states. It is based on simultaneous measurements of the light-induced changes of the optical absorption and of the corresponding EPR signals. Moreover, indirectly optical bands of EPR-silent defects can also be labelled in this way, strongly widening the scope of EPR based defect studies. We apply this method to the infrared-sensitive photorefractive system BaTiO 3 :Rh, where illumination leads to recharging among the valence states Rh 5+ , Rh 4+ and Rh 3+ . The values of all parameters governing the charge transfers responsible are inferred from the magnitude of the absorption bands, the absolute determination of their absorption cross-sections and the kinetics of the absorption changes under illumination. In contrast to previous investigations, these parameters are deduced independently of photorefractive measurements

The EPR in a few words: all you need to know about the EPR nuclear reactor

International Nuclear Information System (INIS)

2009-01-01

After a brief presentation of the EPR (European - or Evolutionary - Pressurized Reactor) type nuclear reactor, this paper, proposed by the collective group 'Stop EPR', develops the following points: EPR is as dangerous as other reactors; EPR flouts democracy; France's energy demand do not need the construction of EPRs; the construction of EPRs is not a factor of economical and social development; EPR should not be constructed neither in France nor elsewhere and the present building sites should be cancelled; the EPR will not help France to increase its energy independence and protect itself from oil price increases; choosing the EPR is incompatible with the large investments to be made in energy conservation and renewable energies; the EPR is not a solution to climate change; the VHV line corridor that will starts at Flamanville is not justified and poses risks to the environment and public health

Biomolecular EPR spectroscopy

CERN Document Server

Hagen, Wilfred Raymond

2008-01-01

Comprehensive, Up-to-Date Coverage of Spectroscopy Theory and its Applications to Biological SystemsAlthough a multitude of books have been published about spectroscopy, most of them only occasionally refer to biological systems and the specific problems of biomolecular EPR (bioEPR). Biomolecular EPR Spectroscopy provides a practical introduction to bioEPR and demonstrates how this remarkable tool allows researchers to delve into the structural, functional, and analytical analysis of paramagnetic molecules found in the biochemistry of all species on the planet. A Must-Have Reference in an Intrinsically Multidisciplinary FieldThis authoritative reference seamlessly covers all important bioEPR applications, including low-spin and high-spin metalloproteins, spin traps and spin lables, interaction between active sites, and redox systems. It is loaded with practical tricks as well as do's and don'ts that are based on the author's 30 years of experience in the field. The book also comes with an unprecedented set of...

EPR by Areva. EPR the 1600+ MWe reactor

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

This brochure presents the GEN III+ EPR reactor designed by the Areva and Siemens consortium. The EPR reactor is a direct descendent of the well-proven N4 and KONVOI reactors, the most modern reactors in France and Germany. The EPR was designed by teams from KWU/Siemens and Framatome, EDF in France and the major German utilities, working in collaboration with both French and German safety authorities. The EPR integrates the results of decades of R and D programs, in particular those performed by the CEA (French Atomic Energy Commission) and the Karlsruhe Research Center in Germany. The EPR benefits from the experience of several thousand reactor-years of operation of pressurized water reactor technology. This experience has put 87 AREVA PWRs online throughout the world. Innovative Features: - An outer shell covering the reactor building, the spent fuel building and two of the four safeguard buildings provides protection against large commercial or military aircraft crash. - A heavy neutron reflector that surrounds the reactor core lowers uranium consumption. - An axial economizer inside the steam generator allows a high level of steam pressure and therefore high plant efficiency. - A core catcher allows passive collection and retention of the molten core should the reactor vessel fail in the highly unlikely event of a core melt. - A digital technology and a fully computerized control room with an operator friendly man-machine interface improve the reactor protection system.

EPR by Areva. EPR the 1600+ MWe reactor

International Nuclear Information System (INIS)

2008-01-01

This brochure presents the GEN III+ EPR reactor designed by the Areva and Siemens consortium. The EPR reactor is a direct descendent of the well-proven N4 and KONVOI reactors, the most modern reactors in France and Germany. The EPR was designed by teams from KWU/Siemens and Framatome, EDF in France and the major German utilities, working in collaboration with both French and German safety authorities. The EPR integrates the results of decades of R and D programs, in particular those performed by the CEA (French Atomic Energy Commission) and the Karlsruhe Research Center in Germany. The EPR benefits from the experience of several thousand reactor-years of operation of pressurized water reactor technology. This experience has put 87 AREVA PWRs online throughout the world. Innovative Features: - An outer shell covering the reactor building, the spent fuel building and two of the four safeguard buildings provides protection against large commercial or military aircraft crash. - A heavy neutron reflector that surrounds the reactor core lowers uranium consumption. - An axial economizer inside the steam generator allows a high level of steam pressure and therefore high plant efficiency. - A core catcher allows passive collection and retention of the molten core should the reactor vessel fail in the highly unlikely event of a core melt. - A digital technology and a fully computerized control room with an operator friendly man-machine interface improve the reactor protection system

Two copies of the Einstein-Podolsky-Rosen state of light lead to refutation of EPR ideas.

Science.gov (United States)

Rosołek, Krzysztof; Stobińska, Magdalena; Wieśniak, Marcin; Żukowski, Marek

2015-03-13

Bell's theorem applies to the normalizable approximations of original Einstein-Podolsky-Rosen (EPR) state. The constructions of the proof require measurements difficult to perform, and dichotomic observables. By noticing the fact that the four mode squeezed vacuum state produced in type II down-conversion can be seen both as two copies of approximate EPR states, and also as a kind of polarization supersinglet, we show a straightforward way to test violations of the EPR concepts with direct use of their state. The observables involved are simply photon numbers at outputs of polarizing beam splitters. Suitable chained Bell inequalities are based on the geometric concept of distance. For a few settings they are potentially a new tool for quantum information applications, involving observables of a nondichotomic nature, and thus of higher informational capacity. In the limit of infinitely many settings we get a Greenberger-Horne-Zeilinger-type contradiction: EPR reasoning points to a correlation, while quantum prediction is an anticorrelation. Violations of the inequalities are fully resistant to multipair emissions in Bell experiments using parametric down-conversion sources.

EPR and IR spectral investigations on some leafy vegetables of Indian origin

Science.gov (United States)

Prasuna, C. P. Lakshmi; Chakradhar, R. P. S.; Rao, J. L.; Gopal, N. O.

2009-09-01

EPR spectral investigations have been carried out on four edible leafy vegetables of India, which are used as dietary component in day to day life. In Rumex vesicarius leaf sample, EPR spectral investigations at different temperatures indicate the presence of anti-ferromagnetically coupled Mn(IV)-Mn(IV) complexes. EPR spectra of Trigonella foenum graecum show the presence of Mn ions in multivalent state and Fe 3+ ions in rhombic symmetry. EPR spectra of Basella rubra indicate the presence of Mn(IV)-O-Mn(IV) type complexes. The EPR spectra of Basella rubra have been studied at different temperatures. It is found that the spin population for the resonance signal at g = 2.06 obeys the Boltzmann distribution law. The EPR spectra of Moringa oliefera leaves show the presence of Mn 2+ ions. Radiation induced changes in free radical of this sample have also been studied. The FT-IR spectra of Basella rubra and Moringa oliefera leaves show the evidences for the protein matrix bands and those corresponding to carboxylic C dbnd O bonds.

The sensitivity analysis of tooth enamel to the absorbed dose for the application to EPR dosimetry

International Nuclear Information System (INIS)

Hong, Dae Seok; Lee, Kun Jai; Cho, Young Hwan

2002-01-01

Electron Paramagnetic Resonance (EPR) spectroscopy is one of the methods applicable to retrospective dosimetry. The retrospective dosimetry is a process that is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. Many techniques can be used to the retrospective dosimetry. As a physical method, EPR analysis of biological material measures the quantity of free radicals generated in the material from the interaction of radiation and material. Since the later 80s, in many countries, EPR dosimetry with tooth enamel has been studied and applied for the retrospective dosimetry. In the consideration of the biological materials for EPR dosimetry, human fingernail, hair, bone and tooth are generally considered. The tooth can be separated as enamel, dentine and cementum. Among the three parts, enamel shows the best sensitivity to the absorbed dose and is most widely used. In this study, the characteristics of tooth enamel for EPR dosimetry is examined and experimented. At the experiment, for easy separation, tooth was cut into 4 parts and then each part is treated by ultrasonic vibration in NaOH liquid to reduce mechanically induced noise in the corresponding signal. After the separation of the enamel from dentine, background EPR signal is measured and then radiation-induced EPR spectrum is estimated

EPR of free radicals in solids II trends in methods and applications

CERN Document Server

Lund, Anders; Lund, Anders

2012-01-01

EPR of Free Radicals in Solids: Trends in Methods and Applications, 2nd ed. presents a critical two volume review of the methods and applications of EPR (ESR) for the study of free radical processes in solids. Emphasis is on the progress made in the developments in EPR technology, in the application of sophisticated matrix isolation techniques and in the advancement in quantitative EPR that have occurred since the 1st edition was published. Improvements have been made also at theoretical level, with the development of methods based on first principles and their application to the calculation of magnetic properties as well as in spectral simulations. EPR of Free Radicals in Solids II focuses on the trends in applications of experimental and theoretical methods to extract structural and dynamical properties of radicals and spin probes in solid matrices by continuous wave (CW) and pulsed techniques in nine chapters written by experts in the field. It examines the studies involving radiation- and photo-induced in...

Study on the EPR/dosimetric properties of some substituted alanines

International Nuclear Information System (INIS)

Gancheva, Veselka; Sagstuen, Einar; Yordanov, Nicola D.

2006-01-01

Polycrystalline phenyl-alanine and perdeuterated l-α-alanine (l-α-alanine-d 4 ) were studied as potential high-energy radiation-sensitive materials (RSM) for solid state/EPR dosimetry. It was found that phenyl-alanine exhibits a linear dose response in the dose region 0.1-17kGy. However, phenyl-alanine is about 10 times less sensitive to γ-irradiation than standard l-α-alanine irradiated at the same doses. Moreover, the EPR response from phenyl-alanine is unstable and, independent of the absorbed dose, decreases by about 50% within 20 days after irradiation upon storage at room temperature. γ-irradiated polycrystalline perdeuterated l-α-alanine (CD 3 CD(NH 2 )COOH) has not previously been studied at room temperature by EPR spectroscopy. The first part of the present analysis was with respect to the structure of the EPR spectrum. By spectrum simulations, the presence of at least two radiation induced free radicals, R 1 =CH 3 C*(H)COOH and R 2 =H 3 N + -C*(CH 3 )COO - , was confirmed very clearly. Both these radicals were suggested previously from EPR and ENDOR studies of standard alanine crystals. The further investigations into the potential use of alanine-d 4 as RSM, after choosing optimal EPR spectrometer settings parameters for this purpose, show that it is ca. two times more sensitive than standard l-α-alanine

Emergency EPR and OSL dosimetry with table vitamins and minerals.

Science.gov (United States)

Sholom, S; McKeever, S W S

2016-12-01

Several table vitamins, minerals and L-lysine amino acid have been preliminarily tested as potential emergency dosemeters using electron paramagnetic resonance (EPR) and optically stimulated luminescence (OSL) techniques. Radiation-induced EPR signals were detected in samples of vitamin B2 and L-lysine while samples of multivitamins of different brands as well as mineral Mg demonstrated prominent OSL signals after exposure to ionizing radiation doses. Basic dosimetric properties of the radiation-sensitive substances were studied, namely dose response, fading of the EPR or OSL signals and values of minimum measurable doses (MMDs). For EPR-sensitive samples, the EPR signal is converted into units of dose using a linear dose response and correcting for fading using the measured fading dependence. For OSL-sensitive materials, a multi-aliquot, enhanced-temperature protocol was developed to avoid the problem of sample sensitization and to minimize the influence of signal fading. The sample dose in this case is also evaluated using the dose response and fading curves. MMDs of the EPR-sensitive samples were below 2 Gy while those of the OSL-sensitive materials were below 500 mGy as long as the samples are analyzed within 1 week after exposure. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

EPR: Evidence and fallacy.

Science.gov (United States)

Nichols, Joseph W; Bae, You Han

2014-09-28

The enhanced permeability and retention (EPR) of nanoparticles in tumors has long stood as one of the fundamental principles of cancer drug delivery, holding the promise of safe, simple and effective therapy. By allowing particles preferential access to tumors by virtue of size and longevity in circulation, EPR provided a neat rationale for the trend toward nano-sized drug carriers. Following the discovery of the phenomenon by Maeda in the mid-1980s, this rationale appeared to be well justified by the flood of evidence from preclinical studies and by the clinical success of Doxil. Clinical outcomes from nano-sized drug delivery systems, however, have indicated that EPR is not as reliable as previously thought. Drug carriers generally fail to provide superior efficacy to free drug systems when tested in clinical trials. A closer look reveals that EPR-dependent drug delivery is complicated by high tumor interstitial fluid pressure (IFP), irregular vascular distribution, and poor blood flow inside tumors. Furthermore, the animal tumor models used to study EPR differ from clinical tumors in several key aspects that seem to make EPR more pronounced than in human patients. On the basis of this evidence, we believe that EPR should only be invoked on a case-by-case basis, when clinical evidence suggests the tumor type is susceptible. Copyright © 2014 Elsevier B.V. All rights reserved.

Clinical EPR: Unique Opportunities and Some Challenges

Science.gov (United States)

Swartz, Harold M.; Williams, Benjamin B.; Zaki, Bassem I.; Hartford, Alan C.; Jarvis, Lesley A.; Chen, Eunice; Comi, Richard J.; Ernstoff, Marc S.; Hou, Huagang; Khan, Nadeem; Swarts, Steven G.; Flood, Ann B.; Kuppusamy, Periannan

2014-01-01

Electron paramagnetic resonance (EPR) spectroscopy has been well established as a viable technique for measurement of free radicals and oxygen in biological systems, from in vitro cellular systems to in vivo small animal models of disease. However, the use of EPR in human subjects in the clinical setting, although attractive for a variety of important applications such as oxygen measurement, is challenged with several factors including the need for instrumentation customized for human subjects, probe and regulatory constraints. This paper describes the rationale and development of the first clinical EPR systems for two important clinical applications, namely, measurement of tissue oxygen (oximetry), and radiation dose (dosimetry) in humans. The clinical spectrometers operate at 1.2 GHz frequency and use surface loop resonators capable of providing topical measurements up to 1 cm depth in tissues. Tissue pO2 measurements can be carried out noninvasively and repeatedly after placement of an oxygen-sensitive paramagnetic material (currently India ink) at the site of interest. Our EPR dosimetry system is capable of measuring radiation-induced free radicals in the tooth of irradiated human subjects to determine the exposure dose. These developments offer potential opportunities for clinical dosimetry and oximetry, which include guiding therapy for individual patients with tumors or vascular disease, by monitoring of tissue oxygenation. Further work is in progress to translate this unique technology to routine clinical practice. PMID:24439333

Locations of radical species in black pepper seeds investigated by CW EPR and 9GHz EPR imaging.

Science.gov (United States)

Nakagawa, Kouichi; Epel, Boris

2014-10-15

In this study, noninvasive 9GHz electron paramagnetic resonance (EPR)-imaging and continuous wave (CW) EPR were used to investigate the locations of paramagnetic species in black pepper seeds without further irradiation. First, lithium phthalocyanine (LiPC) phantom was used to examine 9GHz EPR imaging capabilities. The 9GHz EPR-imager easily resolved the LiPC samples at a distance of ∼2mm. Then, commercially available black pepper seeds were measured. We observed signatures from three different radical species, which were assigned to stable organic radicals, Fe(3+), and Mn(2+) complexes. In addition, no EPR spectral change in the seed was observed after it was submerged in distilled H2O for 1h. The EPR and spectral-spatial EPR imaging results suggested that the three paramagnetic species were mostly located at the seed surface. Fewer radicals were found inside the seed. We demonstrated that the CW EPR and 9GHz EPR imaging were useful for the determination of the spatial distribution of paramagnetic species in various seeds. Copyright © 2014 Elsevier B.V. All rights reserved.

Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations.

Science.gov (United States)

Crăciun, Cora

2014-08-01

CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids' EPR behaviour, for different spin system symmetries. The metrics' efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method. Copyright © 2014 Elsevier Inc. All rights reserved.

Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations

Science.gov (United States)

Crăciun, Cora

2014-08-01

CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids’ EPR behaviour, for different spin system symmetries. The metrics’ efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method.

Preliminary study on electron paramagnetic resonance (EPR) signal properties of mobile phone components for dose estimation in radiation accident

Energy Technology Data Exchange (ETDEWEB)

Park, Byeong Ryong; Ha, Wi Ho; Park, Sun Hoo; Lee, Jin Kyeong; Lee, Seung Sook [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)

2015-12-15

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by {sup 137}C{sub s} gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity (R{sup 2} > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

EPR-based material modelling of soils

Science.gov (United States)

Faramarzi, Asaad; Alani, Amir M.

2013-04-01

In the past few decades, as a result of the rapid developments in computational software and hardware, alternative computer aided pattern recognition approaches have been introduced to modelling many engineering problems, including constitutive modelling of materials. The main idea behind pattern recognition systems is that they learn adaptively from experience and extract various discriminants, each appropriate for its purpose. In this work an approach is presented for developing material models for soils based on evolutionary polynomial regression (EPR). EPR is a recently developed hybrid data mining technique that searches for structured mathematical equations (representing the behaviour of a system) using genetic algorithm and the least squares method. Stress-strain data from triaxial tests are used to train and develop EPR-based material models for soil. The developed models are compared with some of the well-known conventional material models and it is shown that EPR-based models can provide a better prediction for the behaviour of soils. The main benefits of using EPR-based material models are that it provides a unified approach to constitutive modelling of all materials (i.e., all aspects of material behaviour can be implemented within a unified environment of an EPR model); it does not require any arbitrary choice of constitutive (mathematical) models. In EPR-based material models there are no material parameters to be identified. As the model is trained directly from experimental data therefore, EPR-based material models are the shortest route from experimental research (data) to numerical modelling. Another advantage of EPR-based constitutive model is that as more experimental data become available, the quality of the EPR prediction can be improved by learning from the additional data, and therefore, the EPR model can become more effective and robust. The developed EPR-based material models can be incorporated in finite element (FE) analysis.

Using rapid-scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude.

Science.gov (United States)

Möser, J; Lips, K; Tseytlin, M; Eaton, G R; Eaton, S S; Schnegg, A

2017-08-01

X-band rapid-scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid-scan and continuous-wave EPR spectra were recorded for amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid-scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid-scan EPR results in signal-to-noise improvements by factors between 10 and 50. Rapid-scan EPR is thus capable of improving the detection limit of quantitative EPR by at least one order of magnitude. In addition, we provide a recipe for setting up and calibrating a conventional pulsed and continuous-wave EPR spectrometer for rapid-scan EPR. Copyright © 2017 Elsevier Inc. All rights reserved.

Investigation of radical locations in various sesame seeds by CW EPR and 9-GHz EPR imaging.

Science.gov (United States)

Nakagawa, K; Hara, H

2015-01-01

We investigated the location of radical in various sesame seeds using continuous-wave (CW) electron paramagnetic resonance (EPR) and 9-GHz EPR imaging. CW EPR detected persistent radicals (single line) for various sesame seeds. The EPR linewidth of black sesame seeds was narrower than that of the irradiated white sesame seeds. A very small signal was detected for the white sesame seeds. Two-dimensional (2D) imaging using a 9-GHz EPR imager showed that radical locations vary for various sesame seeds. The paramagnetic species in black sesame seeds were located on the seed coat (skin) and in the hilum region. The signal with the highest intensity was obtained from the hilum part. A very low-intensity image was observed for the white sesame seeds. In addition, the 2D imaging of the irradiated white sesame seeds showed that free radicals were located throughout the entire seed. For the first time, CW EPR and 9-GHz EPR imaging showed the exact location of radical species in various sesame seeds.

Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

Energy Technology Data Exchange (ETDEWEB)

Yordanov, Nicola D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)], E-mail: ndyepr@bas.bg; Aleksieva, Katerina [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

2009-03-15

The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 deg. C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048{+-}0.0005 before irradiation. Irradiation gives rise to typical 'cellulose-like' EPR spectrum featuring one intensive line with g=2.0048{+-}0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs-Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.

Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

International Nuclear Information System (INIS)

Yordanov, Nicola D.; Aleksieva, Katerina

2009-01-01

The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 deg. C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048±0.0005 before irradiation. Irradiation gives rise to typical 'cellulose-like' EPR spectrum featuring one intensive line with g=2.0048±0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs-Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs

Preparation and applicability of fresh fruit samples for the identification of radiation treatment by EPR

Science.gov (United States)

Yordanov, Nicola D.; Aleksieva, Katerina

2009-03-01

The results of electron paramagnetic resonance (EPR) study on fresh fruits (whole pulp of pears, apples, peaches, apricots, avocado, kiwi and mango) before and after gamma-irradiation are reported using two drying procedures before EPR investigation. In order to remove water from non-irradiated and irradiated samples of the first batch, the pulp of fresh fruits is pressed, and the solid residue is washed with alcohol and dried at room temperature. The fruits of the second batch are pressed and dried in a standard laboratory oven at 40 °C. The results obtained with both drying procedures are compared. All samples under study show a singlet EPR line with g=2.0048±0.0005 before irradiation. Irradiation gives rise to typical "cellulose-like" EPR spectrum featuring one intensive line with g=2.0048±0.0005 and two very weak satellite lines situated 3 mT at left and right of the central line. Only mango samples show a singlet line after irradiation. The fading kinetics of radiation-induced EPR signal is studied for a period of 50 days after irradiation. When the irradiated fruit samples are stored in their natural state and dried just before each EPR measurement, the satellite lines are measurable for less than 17 days of storage. Irradiated fruit samples, when stored dried, lose for 50 days ca. 40% of their radiation-induced radicals if treated with alcohol or ca. 70% if dried in an oven. The reported results unambiguously show that the presence of the satellite lines in the EPR spectra could be used for identification of radiation processing of fresh fruits, thus extending the validity of European Protocol EN 1787 (2000). Foodstuffs—Detection of Irradiated Food Containing Cellulose by EPR Spectroscopy. European Committee for Standardisation. Brussels for dry herbs.

Photoinduced electron transfer to fullerene C70 (An in situ EPR study)

International Nuclear Information System (INIS)

Brezova, V.; Dvoranova, D.; Kostova, B.; Stasko, A.

1999-01-01

The photoexcitation of fullerene C 70 by monochromatic light (λ = 546 nm) in the presence of electron donating substrate 3,3',5,5'-tetramethyl-benzidine (TMB) resulted in the charge-transfer, quenching the fullerene triplet state and forming corresponding C 70 anion-radicals. Analogously to the photo-reduction of C 60 , two EPR signal were observed upon in situ irradiation in the cavity of EPR spectrometer. EPR singlet A characterized by g-value, g A = 2.0009 and peak-to-peak line-width, pp A = 0.013 mT was assigned to the C 70 mono-anion. Signal B (g B = 2.0011; pp B = 0.011 mT) was tentatively attributed to the C 70 di-anion or to the associated forms of mono-anions. The stabilization of photo-generated anion-radicals significantly depends on solvent polarity. (authors)

Quantitative EPR A Practitioners Guide

CERN Document Server

Eaton, Gareth R; Barr, David P; Weber, Ralph T

2010-01-01

This is the first comprehensive yet practical guide for people who perform quantitative EPR measurements. No existing book provides this level of practical guidance to ensure the successful use of EPR. There is a growing need in both industrial and academic research to provide meaningful and accurate quantitative EPR results. This text discusses the various sample, instrument and software related aspects required for EPR quantitation. Specific topics include: choosing a reference standard, resonator considerations (Q, B1, Bm), power saturation characteristics, sample positioning, and finally, putting all the factors together to obtain an accurate spin concentration of a sample.

Evaluation of the original dose in irradiated dried fruit by EPR spectroscopy

International Nuclear Information System (INIS)

D'Oca, Maria Cristina; Bartolotta, Antonio

2011-01-01

The electron paramagnetic resonance spectroscopy (EPR) is one of the physical methods, recommended by the European Committee for Standardization, for the identification of irradiated food containing cellulose, such as dried fruit. In this work the applicability of EPR as identification method of irradiated pistachios, hazelnuts, peanuts, chestnuts, pumpkin seeds is evaluated; the time stability of the radiation induced signal is studied and the single aliquot additive dose method is used to evaluate the dose in the product.

Evaluation of the original dose in irradiated dried fruit by EPR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

D' Oca, Maria Cristina, E-mail: mcristina.doca@unipa.it [Dipartimento Farmacochimico, Tossicologico e Biologico, Universita di Palermo, via Archirafi 32, 90123 Palermo (Italy); Bartolotta, Antonio [Dipartimento Farmacochimico, Tossicologico e Biologico, Universita di Palermo, via Archirafi 32, 90123 Palermo (Italy)

2011-09-15

The electron paramagnetic resonance spectroscopy (EPR) is one of the physical methods, recommended by the European Committee for Standardization, for the identification of irradiated food containing cellulose, such as dried fruit. In this work the applicability of EPR as identification method of irradiated pistachios, hazelnuts, peanuts, chestnuts, pumpkin seeds is evaluated; the time stability of the radiation induced signal is studied and the single aliquot additive dose method is used to evaluate the dose in the product.

Towards EPR (European pressurized reactor)

International Nuclear Information System (INIS)

Anon.

2003-01-01

According to the French industry minister, it is nonsense continuing delaying the construction of an EPR prototype because France needs it in order to renew timely its park of nuclear reactors. The renewing is expected to begin in 2020 and will be assured with third generation reactors like EPR. A quick launching of the EPR prototype is necessary to have it being in service by 2012, the feedback operating experience that will be accumulated over the 8 years that will follow will be necessary to optimize the industrial version and to have it ready by 2020. The EPR reactor has indisputable assets: modern, safer, more competitive and it will produce less wastes than present nuclear reactors. The construction cost of an EPR prototype is estimated to 3 milliard Euros and the nuclear industry operators propose to finance it completely. The EPR prototype does not jeopardize the ambitious French program about renewable energy sources, France is committed to produce 21% of its electricity from renewable energies by 2010 and 10 milliard Euros will be invested over this period on wind energy. Nuclear energy and alternative energies must be considered as 2 aspects of a diversified energy policy. (A.C.)

Identification and dose assessment of irradiated cardamom and cloves by EPR spectrometry

International Nuclear Information System (INIS)

Beshir, W.B.

2014-01-01

The use of electron paramagnetic resonance spectroscopy to accurately distinguish irradiated from unirradiated cardamom and cloves and assesses the absorbed dose to radiation processed cardamom and cloves are examined. The results were successful for identifying both irradiated and unirradiated cardamom and cloves. Additive reirradiation of cardamom and cloves produces reproducible dose–response functions, which can be used to assess the initial dose by back-extrapolation. Third degree polynomial function was used to fit the EPR signal/dose curves. It was found that this 3rd degree polynomial function provides satisfactory results without correction of decay for free radicals. The stability of the radiation induced EPR signal of irradiated cardamom and cloves were studied over a storage period of almost 8 months. The calculated G-value (The number of radicals per 100 eV of absorbed energy) for cardamom and cloves was found 0.07±0.01 and 0.055±0.01, respectively. - Highlights: • The EPR analysis of cardamom and cloves prove the sample has been irradiated or not. • Dose additive can be used for evaluation of the absorbed dose in cardamom and cloves. • The 3rd polynomial function can be used to fit the data and the estimated dose. • The stability of the radiation induced EPR signal of irradiated cardamom and cloves were studied over 2 months

Copenhagen vs Everett, teleportation, and ER=EPR

Energy Technology Data Exchange (ETDEWEB)

Susskind, Leonard [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States)

2016-06-15

Quantum gravity may have as much to tell us about the foundations and interpretation of quantum mechanics as it does about gravity. The Copenhagen interpretation of quantum mechanics and Everett's Relative State Formulation are complementary descriptions which in a sense are dual to one another. My purpose here is to discuss this duality in the light of the of ER=EPR conjecture. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Using rapid scan EPR to improve the detection limit of quantitative EPR by more than one order of magnitude

OpenAIRE

Möser, J.; Lips, K.; Tseytlin, M.; Eaton, G.; Eaton, S.; Schnegg, A

2017-01-01

X band rapid scan EPR was implemented on a commercially available Bruker ELEXSYS E580 spectrometer. Room temperature rapid scan and continuous wave EPR spectra were recorded for amorphous silicon powder samples. By comparing the resulting signal intensities the feasibility of performing quantitative rapid scan EPR is demonstrated. For different hydrogenated amorphous silicon samples, rapid scan EPR results in signal to noise improvements by factors between 10 and 50. Rapid scan EPR is thus ca...

Medical application of EPR

International Nuclear Information System (INIS)

Eichhoff, Uwe; Hoefer, Peter

2015-01-01

Selected applications of continuous-wave EPR in medicine are reviewed. This includes detection of reactive oxygen and nitrogen species, pH measurements and oxymetry. Applications of EPR imaging are demonstrated on selected examples and future developments to faster imaging methods are discussed

EPR paradox revisited

Energy Technology Data Exchange (ETDEWEB)

Cantrell, C.D.; Scully, M.O.

1978-07-01

Einstein, Podolsky, and Rosen (EPR) argued in 1935 that quantum mechanics fails to give an adequate description of physical reality, and also cannot give a consistent wave-function description of certain phenomena. It is shown that a calculation based upon the reduced density matrix removes the formal inconsistency pointed out by EPR. The spirit of the present paper is that of a pedagogical review.

Rapid-scan EPR imaging.

Science.gov (United States)

Eaton, Sandra S; Shi, Yilin; Woodcock, Lukas; Buchanan, Laura A; McPeak, Joseph; Quine, Richard W; Rinard, George A; Epel, Boris; Halpern, Howard J; Eaton, Gareth R

2017-07-01

In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250MHz. Copyright © 2017 Elsevier Inc. All rights reserved.

EPR spectroscopy at DNP conditions

International Nuclear Information System (INIS)

Heckmann, J.; Goertz, St.; Meyer, W.; Radtke, E.; Reicherz, G.

2004-01-01

In terms of dynamic nuclear polarization (DNP) studies and systematic target material research it is crucial to know the EPR lineshape of the DNP relevant paramagnetic centers. Therefore in Bochum an EPR spectrometer has been implemented into the 4 He evaporation DNP facility in order to perform EPR studies at DNP conditions (B=2.5 T, T=1 K). The spectrometer hardware and performance as well as first results are presented

Geographic Variations in the EPR Spectrum of Tooth Enamel

International Nuclear Information System (INIS)

Romanyukha, A.A.; Hayes, R.B.; Haskell, E.H.; Kenner, G.H.

1999-01-01

The presence of stable radiation-induced radicals in the mineral component of tooth enamel allows use of this material as a biological dosemeter. Estimation of the dose absorbed in tooth enamel can be done by EPR. Generally, for the purpose of dose reconstruction, the EPR spectrum of tooth enamel is interpreted in terms of two main components. The first is a broad background signal often called the native signal centered at a g value of 2.0045. The origin of this signal is not precisely known. The second main component in the tooth enamel spectrum is purely radiation induced and can be used for retrospective dosimetry. Internal structure of the native signal and variations of its amplitude and linewidth were investigated for the samples prepared from modern teeth obtained from different geographic locations (USA and Russia). Possible reasons for the variations observed are discussed as are the potential effects of the variations on the reliability of dose estimation. (author)

EPR dosimetry of irradiated human teeth

International Nuclear Information System (INIS)

Rodas Duran, J.E.; Panzeri, H.; Mascarenhas, S.

1985-01-01

The determination of the absorbed radiation dose in man may be made by Electron Paramagnetic Resonance (EPR) spectroscopy of dental enamel. We analysed the EPR signals for dental enamel submitted to gamma radiation in doses between 1 Gy and 25 Gy. We conclude that independent of the type of tooth analysed there exists a linear relation between the EPR signals and the absorbed doses. These studies were extended to enamel irradiated with gamma rays and with X rays in doses between 0.1 Gy and 0.6 Gy. The graph of the intensity of the EPR signals as a function of the dose has a slope of 0.22. This calibration may be used to calculate the absorbed dose for humans from a measurement of the EPR signal from small samples of enamel taken from any permanent tooth. Finally we comment on some EPR studies of effects of radiation of milk teeth. (author)

Development of a new dosimeter of EPR based on lactose

International Nuclear Information System (INIS)

Cruz C, L.; Torijano C, E.; Azorin N, J.; Aguirre G, F.; Cruz Z, E.

2014-08-01

50 years have passed since was proposed using the amino acid alanine as dosimeter advantage the phenomenon of electron paramagnetic resonance (EPR); this dosimetric method has reached a highly competitive level regarding others dosimetry classic methods, for example the thermoluminescence or the use of Fricke dosimeters, to measure high dose of radiation. In this type of materials, the free radicals induced by the radiation are stable and their concentration is proportional to the absorbed dose may be determined by the amplitude pick to pick of the first derived of the EPR absorption spectrum. The obtained results studying the EPR response of lactose tablets elaborated in the Universidad Autonoma Metropolitana, Unidad Iztapalapa are presented. The tablets were irradiated with gamma radiation of 60 Co in the irradiator Gamma beam 651-Pt of the Instituto de Ciencias Nucleares de la Universidad Nacional Autonoma de Mexico to a dose rate of 8 kGy-h -1 and their EPR response in a EPR spectrometer e-scan Bruker. The obtained response in function of the dose was lineal in the interval of 1 at 10 kGy. The lactose sensibility was compared with the l-alanine, used as reference, and the result was consistently 0.25 of this. Due to the linearity shown in the interval of used dose and their low production cost, we conclude that the lactose is a promissory option for the dosimetry of high dose of radiation. (author)

MDEP Common Position No EPR-01 - Common positions on the EPR instrumentation and controls design

International Nuclear Information System (INIS)

2010-01-01

The purpose of the EPR Working Group (EPRWG) of the Multinational Design Evaluation Program (MDEP) is to identify common positions among the regulators reviewing the EPR Instrumentation and Controls (I and C) Systems in order to: 1. Promote understanding of each country 's regulatory decisions and basis for the decisions, 2. Enhance communication among the members and with external stakeholders, 3. Identify areas where harmonization and convergence of regulations, standards, and guidance can be achieved or improved, and 4. Supports standardization of new reactor designs. Since January 2008, the EPR I and C Technical Expert Subgroup (TESG) members met five times to exchange information regarding their country 's review of the EPR I and C design. The EPR I and C TESG consists of regulators from China, Canada, Finland, France, the United Kingdom, and the United States. The information exchange includes presentation of each country 's review status and technical issues, sharing of guidance documents, and sharing of regulatory decision documents. The TESG focused on the following four core areas of the EPR I and C design: 1. I and C System Independence (particularly for data communications), 2. Level of Defense and Diversity (back-up systems), 3. Qualification/quality of digital platforms, 4. Categorization/classification of systems and functions. As meetings were conducted, some areas were emphasized more depending on the significance of the issues for each country. During the TESG interactions, it became apparent that there were aspects of the EPR design where the countries had common agreement. On November 2, 2009, three of the subgroup countries, France, Finland and the United Kingdom, issued a joint regulatory position on the EPR I and C design as result of the 'Groupe Permanent' meeting in France. This statement of common positions expands upon that joint regulatory position

Elimination of the background signal in tooth enamel samples for EPR-dosimetry by means of physical-chemical treatment

International Nuclear Information System (INIS)

Ivannikov, A.I.; Tikunov, D.D.; Skvortsov, V.G.; Stepanenko, V.F.; Khomichyonok, V.V.; Khamidova, L.G.; Skripnik, D.D.; Bozadjiev, L.L.; Hoshi, M.

2001-01-01

A method of elimination of the background EPR signal in tooth enamel is proposed. This method implies treatment of enamel powder by highly active reduction reagent hydrazine with subsequent washing out by ethanol-water solution. Such treatment results in reducing both the native background signal (which is assumed to be originated by the organic component) and the mechanical induced EPR signal in enamel. Testing of the efficiency of hydrazine treatment is made for different sizes of enamel powder. It is shown that the optimal results are obtained for a powder fraction of about 100-200 μm. The radiation-induced EPR signal in enamel is practically not changed after treatment by hydrazine

Use of EPR to Solve Biochemical Problems

Science.gov (United States)

Sahu, Indra D.; McCarrick, Robert M.; Lorigan, Gary A.

2013-01-01

EPR spectroscopy is a very powerful biophysical tool that can provide valuable structural and dynamic information on a wide variety of biological systems. The intent of this review is to provide a general overview for biochemists and biological researchers on the most commonly used EPR methods and how these techniques can be used to answer important biological questions. The topics discussed could easily fill one or more textbooks; thus, we present a brief background on several important biological EPR techniques and an overview of several interesting studies that have successfully used EPR to solve pertinent biological problems. The review consists of the following sections: an introduction to EPR techniques, spin labeling methods, and studies of naturally occurring organic radicals and EPR active transition metal systems which are presented as a series of case studies in which EPR spectroscopy has been used to greatly further our understanding of several important biological systems. PMID:23961941

Einstein locality, EPR locality, and the significance for science of the nonlocal character of quantum theory

International Nuclear Information System (INIS)

Stapp, H.P.

1985-10-01

The immense difference between Einstein locality and EPR locality is discussed. The latter provides a basis for establishing the nonlocal character of quantum theory, whereas the former does not. A model representing Heisenberg's idea of physical reality is introduced. It is nondeterministic and holistic: the objects, measuring devices, and their environment are treated as an inseparable entity, with, however, macroscopically localizable attributes. The EPR principle that no disturbance can propagate faster than light is imposed without assuming any structure incompatible with orthodox quantum thinking. This locality requirement renders the model incompatible with rudimentary predictions of quantum theory. A more general proof not depending on any model is also given. A recent argument that purports to show that quantum theory is compatible with EPR locality is examined. It illustrates the importance of the crucial one-world assumption. The significance for science of the failure of EPR locality is discussed

Determination of the Antioxidant Status of the Skin by In Vivo-Electron Paramagnetic Resonance (EPR Spectroscopy

Directory of Open Access Journals (Sweden)

Silke Barbara Lohan

2015-08-01

Full Text Available Organisms produce free radicals which are essential for various metabolic processes (enzymatic oxidation, cellular respiration, signaling. Antioxidants are important chemical compounds that specifically prevent the oxidation of substances by scavenging radicals, especially reactive oxygen species (ROS. Made up of one or two unpaired electrons, ROS are free radicals that are highly reactive and can attack other metabolites. By using electron paramagnetic resonance (EPR spectroscopy, it is possible to measure paramagnetic substances such as free radicals. Therefore the dermal antioxidant activity can be determined by applying semi-stable radicals onto the skin and measuring the antioxidant-induced radical scavenging activity in the skin. In recent years, EPR has been developed as a spectroscopic method for determining the antioxidant status in vivo. Several studies have shown that an additional uptake of dietary supplements, such as carotenoids or vitamin C in physiological concentrations, provide a protective effect against free radicals. Using the EPR technique it could be demonstrated that the radical production in stress situations, such as irradiation with infrared and visible light, was reduced with time. However, not only the oral uptake of antioxidants, but also the topical application of antioxidants, e.g., a hyperforin-rich cream, is very useful against the development of oxidative stress. Regular application of a hyperforin-rich cream reduced radical formation. The skin lipids, which are very important for the barrier function of the skin, were also stabilized.

EFFECT OF CADMIUM(II) ON FREE RADICALS IN DOPA-MELANIN TESTED BY EPR SPECTROSCOPY.

Science.gov (United States)

Zdybel, Magdalena; Pilawa, Barbara; Chodurek, Ewa

2015-01-01

Electron paramagnetic resonance (EPR) spectroscopy may be applied to examine interactions of melanin with metal ions and drugs. In this work EPR method was used to examination of changes in free radical system of DOPA-melanin--the model eumelanin after complexing with diamagnetic cadmium(II) ions. Cadmium(II) may affect free radicals in melanin and drugs binding by this polymer, so the knowledge of modification of properties and free radical concentration in melanin is important to pharmacy. The effect of cadmium(II) in different concentrations on free radicals in DOPA-melanin was determined. EPR spectra of DOPA-melanin, and DOPA-melanin complexes with cadmium(II) were measured by an X-band (9.3 GHz) EPR spectrometer produced by Radiopan (Poznań, Poland) and the Rapid Scan Unit from Jagmar (Krak6w, Poland). The DOPA (3,4-dihydroxyphenylalanine) to metal ions molar ratios in the reaction mixtures were 2:1, 1:1, and 1: 2. High concentrations of o-semiquinone (g ~2.0040) free radicals (~10(21)-10(22) spin/g) characterize DOPA-melanin and its complexes with cadmium(II). Formation of melanin complexes with cadmium(II) increase free radical concentration in DOPA-melanin. The highest free radical concentration was obtained for DOPA-melanin-cadmium(II) (1:1) complexes. Broad EPR lines with linewidths: 0.37-0.73 mT, were measured. Linewidths increase after binding of cadmium(II) to melanin. Changes of integral intensities and linewidths with increasing microwave power indicate the homogeneous broadening of EPR lines, independently on the metal ion concentration. Slow spin-lattice relaxation processes existed in all the tested samples, their EPR lines saturated at low microwave powers. Cadmium(II) causes fastening of spin-lattice relaxation processes in DOPA-melanin. The EPR results bring to light the effect of cadmium(II) on free radicals in melanin, and probably as the consequence on drug binding to eumelanin.

Effect of ferroelastic domain pattern changes on the EPR spectra in TDM

Science.gov (United States)

Zapart, W.; Zapart, M. B.

2011-09-01

This article presents polarized light microscopy studies of the ferroelastic domain structure and the analysis of electron paramagnetic resonance spectra of Cr3+ admixture ions in trigonal double molybdates. The correlation has been found between abnormal EPR lineshape and domain structure in ferroelastic phases of these crystals.

The Finnish EPR dependent on a bridge

International Nuclear Information System (INIS)

Dupin, L.

2010-01-01

A new conflict has emerged between the main contractor Areva and its client TVO, the Finnish energy group. The qualification of a handling bridge has delayed the OL3 project of third EPR reactor at Olkiluoto, Finland. The disagreement concerns the testing procedure and may induce a two year delay in the completion of the project which is now planned for 2012 instead of 2010 initially. (J.S.)

EPR studies of melanin from Cladosporium cladosporioides

International Nuclear Information System (INIS)

Pilawa, B.; Buszman, E.; Latocha, M.; Wilczok, T.

1996-01-01

Free radical properties of Cladosporium cladosporioides mycelium and melanin, and synthetic eumelanin and pheomelanin were studied by electron paramagnetic resonance method. Single EPR line and complex EPR spectrum with hyperfine splitting were measured for model DOPA-melanin and cysteinyldopa-melanin, respectively. EPR spectra of Cladosporium cladosporioides samples and pheomelanin show the same character. The concentration of paramagnetic centers in melanins isolated from Cladosporium cladosporioides is considerably higher than that of crude mycelium, whereas the EPR line widths are lower for mycelium than for melanin samples. For all analyzed samples the increase of EPR signals intensity with the increase of microwave power, and the decrease of intensities after saturation were observed the low values of microwave power sufficient for EPR lines saturation demonstrate that the spin-lattice relaxation times of unpaired electrons in melanins are long. (author)

New developed cylindrical TM010 mode EPR cavity for X-band in vivo tooth dosimetry.

Directory of Open Access Journals (Sweden)

Guo Junwang

Full Text Available EPR tooth in vivo dosimetry is an attractive approach for initial triage after unexpected nuclear events. An X-band cylindrical TM010 mode resonant cavity was developed for in vivo tooth dosimetry and used in EPR applications for the first time. The cavity had a trapezoidal measuring aperture at the exact position of the cavity's cylindrical wall where strong microwave magnetic field H1 concentrated and weak microwave electric field E1 distributed. Theoretical calculations and simulations were used to design and optimize the cavity parameters. The cavity features were evaluated by measuring DPPH sample, intact incisor samples embed in a gum model and the rhesus monkey teeth. The results showed that the cavity worked at designed frequency and had the ability to make EPR spectroscopy in relative high sensitivity. Sufficient modulation amplitude and microwave power could be applied into the aperture. Radiation induced EPR signal could be observed remarkably from 1 Gy irradiated intact incisor within only 30 seconds, which was among the best in scan time and detection limit. The in vivo spectroscopy was also realized by acquiring the radiation induced EPR signal from teeth of rhesus monkey whose teeth was irradiated by dose of 2 Gy. The results suggested that the cavity was sensitive to meet the demand to assess doses of significant level in short time. This cavity provided a very potential option for the development of X-band in vivo dosimetry.

EPR in B physics and elsewhere

International Nuclear Information System (INIS)

Lipkin, H.J.; Tel Aviv Univ.; Argonne National Lab., IL

1997-01-01

The application of Einstein-Podolsky-Rosen correlations in Υ(4s) → B anti B decays to research in CP violation is the first and probably only use of EPR as a technique for research in new physics. Elsewhere highly sophisticated EPR projects question EPR and test its predictions to look for violations of quantum mechanics, hidden variables, Bell''s inequalities, etc

Orientation of crystals in alanine dosimeter assessed by DRS, as seen in EPR spectra evaluation

International Nuclear Information System (INIS)

Grazyna Przybytniak; Zagorski, Z.P.

1996-01-01

The alanine dosimeter made for evaluation by diffuse light reflection spectrophotometry (ALA/DRS) does not show the effect of orientation of crystals. Supposed deviation from random orientation has been investigated by EPR spectroscopy. EPR investigation shows that in spite of the very fine size of L-alanine crystals, they are oriented in thin layers of the polyethylene matrix. Specially prepared films with deliberately well oriented crystals have confirmed this observation. Our ALA/DRS dosimeter can be evaluated by the EPR method for the concentration of free radicals, providing that the dominating crystal orientation in the dosimetric film is indicated on it as an arrow, and the sample is inserted into the magnetic cavity always in the same orientation as has been done during the calibration operation. (author). 6 refs., 2 figs

Use of the Frank sequence in pulsed EPR

DEFF Research Database (Denmark)

Tseitlin, Mark; Quine, Richard W.; Eaton, Sandra S.

2011-01-01

The Frank polyphase sequence has been applied to pulsed EPR of triarylmethyl radicals at 256MHz (9.1mT magnetic field), using 256 phase pulses. In EPR, as in NMR, use of a Frank sequence of phase steps permits pulsed FID signal acquisition with very low power microwave/RF pulses (ca. 1.5m......W in the application reported here) relative to standard pulsed EPR. A 0.2mM aqueous solution of a triarylmethyl radical was studied using a 16mm diameter cross-loop resonator to isolate the EPR signal detection system from the incident pulses. Keyword: Correlation spectroscopy,Multi-pulse EPR,Low power pulses,NMR,EPR...

Identification of irradiated food by EPR-spectroscopy and tomography

International Nuclear Information System (INIS)

Groth, N.; Anders, B.; Nitschke, S.; Schlawe, R.; Herrling, T.

1993-01-01

Food irradiation is used to kill harmful microorganisms (e.g. salmonella), this improving food safety and extending the shelf-life. The electron paramagnetic resonance (EPR) detection of stable, radiation-induced free radicals within the matrix of calcified tissue is well established. An extention of this technique to food provides in suitable cases one of the most promissing methods for detecting that irradiation has been performed. It provides an excellent method for the identification of irradiated foods containing bones or calcified cuticle even in the absence of unirradiated controls. Bones of chicken, pepper grains and lentils were also identified as irradiated some weeks after radiation treatment. The method is rapid and can detect very low doses. With EPR - Tomography the 2D spatial distribution of the irradiation induced stable radicals in the cross section of a chicken bone was measured. The use of ionising radiation to treat certain foodstuffs is increasingly of interest and there is a need to determine wether irradiation has occured, and to what extent. (orig.)

Radiation dose estimation by tooth enamel EPR dosimetry for residents of Dolon and Bodene

International Nuclear Information System (INIS)

Zhumadilov, Kassym; Ivannikov, Alexander; Apsalikov, Kazbek N.

2006-01-01

The method of electron paramagnetic resonance (EPR) dosimetry was applied to the enamel of the teeth extracted from the residents of the Dolon and Bodene settlements of the Beskaragay district, which is the area adjacent to the radioactive fallout of the most contaminating nuclear test of 1949. The individual accidental radiation doses due to the fallout were obtained from the amplitude of the radiation induced EPR signal from the CO 2- radical using the calibration method, after determining the parameters of EPR measurements to obtain the best reproducibility of the signal intensities. It was shown that after subtracting the natural background dose from the total absorbed dose obtained by EPR the residents of Dolon and Bodene received accidental radiation doses up to 356 mGy with an average value of 74.1 ± 45.5 mGy before 1949 while the younger population received up to about 100 mGy with an average value of 11.5 ± 37.7 mGy. (author)

EPR STUDIES OF THERMALLY STERILIZED VASELINUM ALBUM.

Science.gov (United States)

Ramos, Paweł; Pilawa, Barbara

2015-01-01

Electron paramagnetic resonance (EPR) spectroscopy was used for examination of free radicals in thermally treated vaselinum album (VA). Thermal treatment in hot air as sterilization process was tested. Conditions of thermal sterilization were chosen according to the pharmaceutical norms. Vaselinum album was heated at the following conditions (T--temperature, t--time): T = 160°C and t = 120 min, T = 170°C and t = 60 min and T = 180°C and t = 30 min. The aim of this work was to determine concentration and free radical properties of thermally sterilized VA. EPR analysis for VA was done 15 min after sterilization. EPR measurements were done at room temperature. EPR spectra were recorded in the range of microwave power of 2.2-70 mW. g-Factor, amplitudes (A) and line width (ΔBpp) of the spectra were determined. The shape of the EPR spectra was analyzed. Free radical concentration (N) in the heated samples was determined. EPR spectra were not obtained for the non heated VA. EPR spectra were detected for all thermally sterilized samples. The spectra revealed complex character, their asymmetry depends on microwave power. The lowest free radicals concentration was found for the VA sterilized at 180°C during 30 min. EPR spectroscopy is proposed as the method useful for optimization of sterilization process of drugs.

Einstein-Podolsky-Rosen entanglement via nonlinear processes enhanced by electromagnetically induced transparency

International Nuclear Information System (INIS)

Cheng Guangling; Hu Xiangming; Zhong Wenxue

2009-01-01

We show that Einstein-Podolsky-Rosen (EPR) light entanglement is obtainable via the resonant nonlinear interactions enhanced by electromagnetically induced transparency. A three-level system is used as a unified model, where two metastable states are coupled to each other via microwave, or Raman, or two-photon transition, and the upper metastable state is coupled to the excited state. A pair of inner sidebands is amplified as optical cavity modes via the transition from the excited state to the other metastable state. The analysis is presented by using the dressed-atom squeezed-transformed-mode approach. For a proper ratio of the amplitudes of the applied fields, the sum of the variances for two EPR-like operators approaches zero, which corresponds to EPR entanglement.

EPR dosimetric properties of 2-methylalanine pellet for radiation processing application

International Nuclear Information System (INIS)

Soliman, Y.S.; Ali, Laila I.; Moustafa, H.; Tadros, Soad M.

2014-01-01

The dosimetric characteristics of γ-radiation induced free radicals in 2-methylalanine (2MA) pellet dosimeter are investigated using electron paramagnetic resonance (EPR) in the high-dose range of 1–100 kGy. The EPR spectrum of γ-irradiated 2MA exhibits an isotropic EPR signal with seven lines. The dosimeter response is humidity independent in the range of 33–76% relative humidity. The manufactured dosimeter is typically adipose tissue equivalent in the energy level of 0.1–15 MeV. The overall uncertainty (2σ) of the dosimeter is less than 6.9%. - Highlights: • Preparation of 2-methyl alanine pellets for high-dose dosimetry (1–100 kGy). • The dosimeter response is humidity independent in 33–76% relative humidity range during irradiation. • The temperature coefficient equals 0.96%/°C in the range of 21–60 °C. • Overall uncertainty of the dosimeter not exceeds 6.9% at 2σ

Pharmaceutical applications of in vivo EPR

International Nuclear Information System (INIS)

Maeder, K.

1998-01-01

The aim of this article is to discuss the applications of in vivo EPR in the field of pharmacy. In addition to direct detection of free radical metabolites and measurement of oxygen, EPR can be used to characterize the mechanisms of drug release from biodegradable polymers. Unique information about drug concentration, the microenvironment (viscosity, polarity, pH) and biodistribution (by localized measurement or EPR Imaging) can be obtained. (author)

Taking into account radiation protection for the EPR (European pressurized water reactor) design

International Nuclear Information System (INIS)

Michoux, X.

2005-01-01

For a designer, the taking into account of radiation protection for the EPR design is based on several thrusts which concern different scopes as choice of materials, checking of design's options, layout of components and systems able to contain radioactivity in different states of operation (i.e.: pressurizer, tanks, actives systems separated from non actives systems), or the optimization of shielding according to the estimated maintenance during outage or during power operation. The EPR method used for radiation protection studies is close to the safety method (use of dose gauge, demonstration of radiation protection, works with high stake regarding the radiation protection studied in priority, parametric studies with use of one field Radiation protection...). Results of this method place EPR in a satisfactory progress compared to the best existing nuclear plants, regarding collective doses and privileging the most exposed workers. This method has also induced on the EPR Project the choice of working during power operation in order to obtain shorts outages, scrupulously respecting security rules, radiation protection and human factor. (author)

Contribution of Harold M. Swartz to In Vivo EPR and EPR Dosimetry

International Nuclear Information System (INIS)

Gallez, Bernard

2016-01-01

In 2015, we are celebrating half a century of research in the application of Electron Paramagnetic Resonance (EPR) as a biodosimetry tool to evaluate the dose received by irradiated people. During the EPR Biodose 2015 meeting, a special session was organized to acknowledge the pioneering contribution of Harold M. (Hal) Swartz in the field. The article summarizes his main contribution in physiology and medicine. Four emerging themes have been pursued continuously along his career since its beginning: (1) radiation biology; (2) oxygen and oxidation; (3) measuring physiology in vivo; and (4) application of these measurements in clinical medicine. The common feature among all these different subjects has been the use of magnetic resonance techniques, especially EPR. In this article, you will find an impressionist portrait of Hal Swartz with the description of the 'making of' this pioneer, a time-line perspective on his career with the creation of three National Institutes of Health-funded EPR centers, a topic-oriented perspective on his career with a description of his major contributions to Science, his role as a mentor and his influence on his academic children, his active role as founder of scientific societies and organizer of scientific meetings, and the well-deserved international recognition received so far. (author)

The EPR paradox revisited

International Nuclear Information System (INIS)

Cantrell, C.D.; Scully, M.O.

1978-01-01

Einstein, Podolsky and Rosen (EPR) argued in 1935 that quantum mechanics fails to give an adequate description of physical reality, and also cannot give a consistent wave-function description of certain phenomena. The authors show that a calculation based upon the reduced density matrix removes the formal inconsistency pointed out by EPR. The spirit of the present paper is that of a pedagogical review. (Auth.)

SimLabel: a graphical user interface to simulate continuous wave EPR spectra from site-directed spin labeling experiments.

Science.gov (United States)

Etienne, E; Le Breton, N; Martinho, M; Mileo, E; Belle, V

2017-08-01

Site-directed spin labeling (SDSL) combined with continuous wave electron paramagnetic resonance (cw EPR) spectroscopy is a powerful technique to reveal, at the residue level, structural transitions in proteins. SDSL-EPR is based on the selective grafting of a paramagnetic label on the protein under study, followed by cw EPR analysis. To extract valuable quantitative information from SDSL-EPR spectra and thus give reliable interpretation on biological system dynamics, numerical simulations of the spectra are required. Such spectral simulations can be carried out by coding in MATLAB using functions from the EasySpin toolbox. For non-expert users of MATLAB, this could be a complex task or even impede the use of such simulation tool. We developed a graphical user interface called SimLabel dedicated to run cw EPR spectra simulations particularly coming from SDSL-EPR experiments. Simlabel provides an intuitive way to visualize, simulate, and fit such cw EPR spectra. An example of SDSL-EPR spectra simulation concerning the study of an intrinsically disordered region undergoing a local induced folding is described and discussed. We believe that this new tool will help the users to rapidly obtain reliable simulated spectra and hence facilitate the interpretation of their results. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

EPR spectroscopic investigation of psoriatic finger nails.

Science.gov (United States)

Nakagawa, Kouichi; Minakawa, Satoko; Sawamura, Daisuke

2013-11-01

Nail lesions are common features of psoriasis and found in almost half of the patients. However, there is no feasible spectroscopic method evaluating changes and severity of nail psoriasis. EPR (electron paramagnetic resonance) might be feasible for evaluating nail conditions in the patients of psoriasis. Finger nails of five cases with nail psoriasis, (three females and two males) were examined. Nail samples were subjected to the EPR assay. The small piece of the finger nail (1.5 × 5 mm(2)) was incubated in ~50 μM 5-DSA (5-doxylstearic acid) aqueous solutions for about 60 min at 37°C. After rinsing and wiping off the excess 5-DSA solution, the nail samples were measured by EPR. EPR spectra were analyzed using the intensity ratio (Fast/Slow) of the two motions at the peaks of the lower magnetic field. We observed two distinguishable sites on the basis of the EPR results. In addition, the modern EPR calculation was performed to analyze the spectra obtained. The nail psoriasis-related region is 2~3 times higher than that of the control. The present EPR results show that there are two distinguishable sites in the nail. In the case of nail psoriasis, the fragile components are 2~3 times more than those of the control. Thus, the EPR method is thought to be a novel and reliable method of evaluating the nail psoriasis. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

EPR Dosimetry in Irradiated Fingernails

International Nuclear Information System (INIS)

Spinella, M.R.; Dubner, D.L.; Bof, E.

2010-01-01

The Electron Paramagnetic Resonance (EPR) is being transformed in a complementary tool of biologically-based methods for evaluation of dose after accidental radiation exposure. Many efforts are being carried out in laboratories to evaluate the performance of different materials for its use in EPR doses measurements and for improving the current methods for spectrum analysis and calibration curves determinations. In our country the EPR techniques have been used in different areas with dosimetric (alanine) and non dosimetric purposes. Now we are performing the first studies to obtain properly dose response curves to be used for accidental dose assessments through irradiated fingernails. It is by now well known that the fingernails present two types of signals, a background one (BKS), originated in elastic and inelastic mechanical deformations and the radio induced one (RIS), object of interest (I). In this work we will present some of the previous studies performed to characterize the fingernail samples and we analyse the additive dose method for data obtained employing the technique of the substraction of the spectrum recorded at two different microwave powers in order to reduce the BKS signal. Fingernail samples collected from different donors were treated by soaking in water during 10 min and 5 min drying on paper towel and the BKS signals were studied previously its irradiation. The statistical analysis (R statistics) show a distribution with a Standard Deviation of 24% respects to its media. During these studies we also conserved in freezer for more than 6 months irradiated fingernails that, were periodically measured and the statistical analysis of the peak to peak amplitude show a normal distribution through the Quantile correlation test with a SD 11% respected to its median. (authors)

Radiation-induced electron paramagnetic resonance signal and soybean isoflavones content

International Nuclear Information System (INIS)

Oliveira, Marcos R.R. de; Mandarino, José M.G.; Mastro, Nelida L. del

2012-01-01

Electron Paramagnetic Resonance (EPR) is a well-known spectroscopic technique that detects paramagnetic centers and can detect free radicals with high sensitivity. In food, free radicals can be generated by several commonly used industrial processes, such as radiosterilization or heat treatment. EPR spectroscopy is used to detect radioinduced free radicals in food. In this work the relation between EPR signal induced by gamma irradiation treatment and soybean isoflavones content was investigated. Present results did not show correlation between total isoflavones content and the EPR signal. Nevertheless, some isoflavone contents had a negative correlation with the radiation-induced EPR signal. - Highlights: ► Electron Paramagnetic Resonance (EPR) detects free radicals. ► Ionizing radiation as free radicals inducer. ► Total soybean isoflvones do not correlate with radiation-induced EPR intensity but a soybean glucosyl glucoside isoflavone does.

Contribution of Harold M. Swartz to In Vivo EPR and EPR Dosimetry.

Science.gov (United States)

Gallez, Bernard

2016-12-01

In 2015, we are celebrating half a century of research in the application of Electron Paramagnetic Resonance (EPR) as a biodosimetry tool to evaluate the dose received by irradiated people. During the EPR Biodose 2015 meeting, a special session was organized to acknowledge the pioneering contribution of Harold M. (Hal) Swartz in the field. The article summarizes his main contribution in physiology and medicine. Four emerging themes have been pursued continuously along his career since its beginning: (1) radiation biology; (2) oxygen and oxidation; (3) measuring physiology in vivo; and (4) application of these measurements in clinical medicine. The common feature among all these different subjects has been the use of magnetic resonance techniques, especially EPR. In this article, you will find an impressionist portrait of Hal Swartz with the description of the 'making of' this pioneer, a time-line perspective on his career with the creation of three National Institutes of Health-funded EPR centers, a topic-oriented perspective on his career with a description of his major contributions to Science, his role as a mentor and his influence on his academic children, his active role as founder of scientific societies and organizer of scientific meetings, and the well-deserved international recognition received so far. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Characterization of Melanin Radicals in Paraffin-embedded Malignant Melanoma and Nevus Pigmentosus Using X-band EPR and EPR Imaging.

Science.gov (United States)

Nakagawa, Kouichi; Minakawa, Satoko; Sawamura, Daisuke; Hara, Hideyuki

2017-01-01

Continuous wave electron paramagnetic resonance (CW EPR) and X-band (9 GHz) EPR imaging (EPRI) were used to nondestructively investigate the possible differentiation between malignant melanoma (MM) and nevus pigmentosus (NP) melanin radicals in paraffin-embedded specimens. The EPR spectra of both samples were analyzed using linewidth, spectral pattern, and X-band EPRI. The CW-EPR spectra of the MM showed an additional signal overlap. Eumelanin- and pheomelanin-related radicals were observed in the MM specimens. The EPR results revealed that the peak-to-peak linewidths (ΔH pp ) of paraffin-embedded MM and NP samples were 0.65 ± 0.01 and 0.69 ± 0.01 mT, respectively. The g-value was 2.005 for both samples. Moreover, the two-dimensional (2D) EPRI of the MM showed different signal intensities at the different tumor stages, unlike the NP, which displayed fewer variations in signal intensity. Thus, the present results suggest that EPR and 2D EPRI can be useful for characterization of the two melanin radicals in the MM and for determination of their size and concentration.

In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR oximetry

International Nuclear Information System (INIS)

Weaver, John; Yang, Yirong; Purvis, Rebecca; Weatherwax, Theodore; Rosen, Gerald M.; Liu, Ke Jian

2014-01-01

Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O 2 may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O 2 is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO 2 in vivo remains largely uncharacterized. This study investigated striatal tissue pO 2 changes in male C57BL/6 mice (16–20 g) following METH administration using EPR oximetry, a highly sensitive modality to measure pO 2 in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO 2 was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO 2 to 64%. More importantly, pO 2 did not recover fully to control levels even 24 h after administration of a single dose of METH and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO 2 indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO 2 , which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. - Highlights: • Explored striatal tissue pO 2 in vivo after METH administration by EPR oximetry. • pO 2 was reduced by 81% after a single dose and 64% after 3 consecutive daily doses. • pO 2 did not recover fully to control levels even 24 h after a single dose. • Decrease in brain tissue pO 2 may be associated with a decrease in CBF. • Administration of methamphetamine may lead to hypoxic

In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR oximetry

Energy Technology Data Exchange (ETDEWEB)

Weaver, John, E-mail: jmweaver@salud.unm.edu [Center of Biomedical Research Excellence, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Yang, Yirong [Center of Biomedical Research Excellence, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Purvis, Rebecca [Center of Biomedical Research Excellence, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Weatherwax, Theodore [Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Rosen, Gerald M. [Center for Biomedical Engineering and Technology, University of Maryland, Baltimore, MD 21201 (United States); Center for EPR Imaging In Vivo Physiology, University of Maryland, Baltimore, MD 21201 (United States); Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201 (United States); Liu, Ke Jian [Center of Biomedical Research Excellence, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States); Department of Neurology, University of New Mexico Health Sciences Center, Albuquerque, NM 87131 (United States)

2014-03-01

Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O{sub 2} may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O{sub 2} is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO{sub 2}in vivo remains largely uncharacterized. This study investigated striatal tissue pO{sub 2} changes in male C57BL/6 mice (16–20 g) following METH administration using EPR oximetry, a highly sensitive modality to measure pO{sub 2}in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO{sub 2} was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO{sub 2} to 64%. More importantly, pO{sub 2} did not recover fully to control levels even 24 h after administration of a single dose of METH and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO{sub 2} indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO{sub 2}, which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. - Highlights: • Explored striatal tissue pO{sub 2}in vivo after METH administration by EPR oximetry. • pO{sub 2} was reduced by 81% after a single dose and 64% after 3 consecutive daily doses. • pO{sub 2} did not recover fully to control levels even 24 h after a single dose. • Decrease in brain tissue pO{sub 2} may be associated with a decrease in

Operating an EPR: A strong asset in the future European electricity market

International Nuclear Information System (INIS)

Esteve, Bernard; Beutier, Didier

2006-01-01

Recently, two nuclear units have been decided in Europe, both EPR 1,600 MWe. In Finland, TVO Company decided to commission a reactor in 2009 on Olkiluoto site. The license was granted in February 2005 and the construction started in summer. In 2004 in France, EDF Company decided an EPR to be commissioned in 2012 at Flamanville. In both cases, national Parliament vote has given the green light. It is interesting to understand why each company has made such decision. In TVO case, the main driving factor seems to be the need of industrial consumers for low and stable electricity price in a context of growing excess demand. In EDF case, no short term demand, but rather long term electricity company strategy seems to be the main reason. The relation to national energy policy is very clear in both cases. In Finland, the 5. Nuclear Power Plant was decided: - as a key element of the energy mix to meet growing electricity needs while replacing older plants, - to ensure, together with renewables, the fulfillment of the Kyoto commitments, - to secure stable and predictable electricity price for intensive industrial consumers (for instance, paper mills), - to reduce the dependence on electricity import. Here, it is argued more broadly that EPR will be a strong asset in the future European electricity market. To support this argument, we shall describe: 1) to what extent the evolving European electricity market may call for new nuclear units, 2) specific design features explaining why EPR especially fits with expectations, 3) cost assessments giving the conditions of EPR competitiveness, 4) main elements of risk assessment and how they are dealt with. (authors)

POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS

Science.gov (United States)

Tipikin, Dmitriy S.; Swarts, Steven G.; Sidabras, Jason W.; Trompier, François; Swartz, Harold M.

2016-01-01

Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation–reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable

Pulsed-High Field/High-Frequency EPR Spectroscopy

Science.gov (United States)

Fuhs, Michael; Moebius, Klaus

Pulsed high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy is used to disentangle many kinds of different effects often obscured in continuous wave (cw) EPR spectra at lower magnetic fields/microwave frequencies. While the high magnetic field increases the resolution of G tensors and of nuclear Larmor frequencies, the high frequencies allow for higher time resolution for molecular dynamics as well as for transient paramagnetic intermediates studied with time-resolved EPR. Pulsed EPR methods are used for example for relaxation-time studies, and pulsed Electron Nuclear DOuble Resonance (ENDOR) is used to resolve unresolved hyperfine structure hidden in inhomogeneous linewidths. In the present article we introduce the basic concepts and selected applications to structure and mobility studies on electron transfer systems, reaction centers of photosynthesis as well as biomimetic models. The article concludes with an introduction to stochastic EPR which makes use of an other concept for investigating resonance systems in order to increase the excitation bandwidth of pulsed EPR. The limited excitation bandwidth of pulses at high frequency is one of the main limitations which, so far, made Fourier transform methods hardly feasible.

Electron paramagnetic resonance (EPR) in medical dosimetry

International Nuclear Information System (INIS)

Schauer, David A.; Iwasaki, Akinori; Romanyukha, Alexander A.; Swartz, Harold M.; Onori, Sandro

2006-01-01

This paper describes the fundamentals of electron paramagnetic resonance (EPR) and its application to retrospective measurements of clinically significant doses of ionizing radiation. X-band is the most widely used in EPR dosimetry because it represents a good compromise between sensitivity, sample size and water content in the sample. Higher frequency bands (e.g., W and Q) provide higher sensitivity, but they are also greatly influenced by water content. L and S bands can be used for EPR measurements in samples with high water content but they are less sensitive than X-band. Quality control for therapeutic radiation facilities using X-band EPR spectrometry of alanine is also presented

A sub-Kelvin cryogen-free EPR system.

Science.gov (United States)

Melhuish, Simon J; Stott, Chloe; Ariciu, Ana-Maria; Martinis, Lorenzo; McCulloch, Mark; Piccirillo, Lucio; Collison, David; Tuna, Floriana; Winpenny, Richard

2017-09-01

We present an EPR instrument built for operation at Q band below 1K. Our cryogen-free Dewar integrates with a commercial electro-magnet and bridge. A description of the cryogenic and RF systems is given, along with the adaptations to the standard EPR experiment for operation at sub-Kelvin temperatures. As a first experiment, the EPR spectra of powdered Cr 12 O 9 (OH) 3 [Formula: see text] were measured. The sub-Kelvin EPR spectra agree well with predictions, and the performance of the sub-Kelvin system at 5K is compared to that of a commercial spectrometer. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

IN-VIVO RADIATION DOSIMETRY USING PORTABLE L BAND EPR: ON-SITE MEASUREMENT OF VOLUNTEERS IN FUKUSHIMA PREFECTURE, JAPAN

Science.gov (United States)

Miyake, Minoru; Nakai, Yasuhiro; Yamaguchi, Ichiro; Hirata, Hiroshi; Kunugita, Naoki; Williams, Benjamin B.; Swartz, Harold M.

2016-01-01

The aim of this study was to make direct measurements of the possible radiation-induced EPR signals in the teeth of volunteers who were residents in Fukushima within 80 km distance from the Fukushima Nuclear Power plant at the time of the disaster, and continued to live there for at least 3 month after the disaster. Thirty four volunteers were enrolled in this study. These measurements were made using a portable L-band EPR spectrometer, which was originally developed in the EPR Center at Dartmouth. All measurements were performed using surface loop resonators that have been specifically designed for the upper incisor teeth. Potentially these signals include not only radiation-induced signals induced by the incident but also background signals including those from prior radiation exposure from the environment and medical exposure. We demonstrated that it is feasible to transport the dosimeter to the measurement site and make valid measurements. The intensity of the signals that were obtained was not significantly above those seen in volunteers who had not had potential radiation exposures at Fukushima. PMID:27522046

In-vivo radiation dosimetry using portable L band EPR: on-site measurement of volunteers in Fukushima Prefecture, Japan

International Nuclear Information System (INIS)

Miyake, Minoru; Nakai, Yasuhiro; Yamaguchi, Ichiro; Kunugita, Naoki; Hirata, Hiroshi; Williams, Benjamin B.; Swartz, Harold M.

2016-01-01

The aim of this study was to make direct measurements of the possible radiation-induced EPR signals in the teeth of volunteers who were residents in Fukushima within 80 km distance from the Fukushima Nuclear Power plant at the time of the disaster, and continued to live there for at least 3 month after the disaster. Thirty four volunteers were enrolled in this study. These measurements were made using a portable L-band EPR spectrometer, which was originally developed in the EPR Center at Dartmouth. All measurements were performed using surface loop resonators that have been specifically designed for the upper incisor teeth. Potentially these signals include not only radiation-induced signals induced by the incident but also background signals including those from prior radiation exposure from the environment and medical exposure. We demonstrated that it is feasible to transport the dosimeter to the measurement site and make valid measurements. The intensity of the signals that were obtained was not significantly above those seen in volunteers who had not had potential radiation exposures at Fukushima. (authors)

Detection by EPR method of radiation treatment in dried fruits containing crystalline sugar

International Nuclear Information System (INIS)

Lehner, K.; Stachowicz, W.

2006-01-01

The results of EPR (electron paramagnetic resonance) measurements are presented on the detection ability and stability of radiation induced sugar-born radicals in the samples of dried (dehydrated) fruits available in the market and related to doses of 0.5, 1 and 3 kGy, respectively. The experiments have been conducted during 12 months of storage. Measurements were done with an EPR - 10 MINI spectrometer in X band (frequency of microwaves 9.5 GHz), St. Petersburg Instruments Ltd. The aim of the work was to prove the reliability of acceptability of the method in routine control of irradiated food. (author)

Nitrosyl hemoglobins: EPR above 80 K

Energy Technology Data Exchange (ETDEWEB)

Wajnberg, E.; Bemski, G.; El-Jaick, L.J.; Alves, O.C.

1995-03-01

The EPR spectra of nitrosyl hemoglobin and myoglobin in different conditions (native, denatured and lyophilized), as well as of hematin-NO were obtained in the temperature range of 80 K-280 K. There is a substantial and reversible.decrease of the areas of the EPR spectra of all the hemoglobin samples above 150 K. The interpretation of the results implies the existence of two conformational states in thermal equilibrium only one of which is EPR detectable. Thermodynamical parameters are determined for the hexa and penta-coordinated cases. (author). 25 refs, 3 figs.

Nitrosyl hemoglobins: EPR above 80 K

International Nuclear Information System (INIS)

Wajnberg, E.; Bemski, G.; El-Jaick, L.J.; Alves, O.C.

1995-03-01

The EPR spectra of nitrosyl hemoglobin and myoglobin in different conditions (native, denatured and lyophilized), as well as of hematin-NO were obtained in the temperature range of 80 K-280 K. There is a substantial and reversible.decrease of the areas of the EPR spectra of all the hemoglobin samples above 150 K. The interpretation of the results implies the existence of two conformational states in thermal equilibrium only one of which is EPR detectable. Thermodynamical parameters are determined for the hexa and penta-coordinated cases. (author). 25 refs, 3 figs

Retrospective individual dosimetry using EPR of tooth enamel

International Nuclear Information System (INIS)

Skvortzo, V.; Ivannikov, A.; Stepanenko, V.; Wieser, A.; Bougai, A.; Brick, A.; Chumak, V.; Radchuk, V.; Repin, V.; Kirilov, V.

1996-01-01

The results of joint investigations (in the framework of ECP-10 program) aimed on the improvement of the sensitivity and accuracy of the procedure of dose measurement using tooth enamel EPR spectroscopy are presented. It is shown, what the sensitivity of method may be increased using special physical-chemical procedure of the enamel samples treatment, which leads to the reducing of EPR signal of organic components in enamel. Tooth diseases may have an effect on radiation sensitivity of enamel. On the basis of statistical analysis of the results of more then 2000 tooth enamel samples measurements it was shown, what tooth enamel EPR spectroscopy gives opportunity to register contribution into total dose, which is caused by natural environmental radiation and by radioactive contamination. EPR response of enamel to ultraviolet exposure is investigated and possible influences to EPR dosimetry is discussed. The correction factors for EPR dosimetry in real radiation fields are estimated

EPR-based distance measurements at ambient temperature.

Science.gov (United States)

Krumkacheva, Olesya; Bagryanskaya, Elena

2017-07-01

Pulsed dipolar (PD) EPR spectroscopy is a powerful technique allowing for distance measurements between spin labels in the range of 2.5-10.0nm. It was proposed more than 30years ago, and nowadays is widely used in biophysics and materials science. Until recently, PD EPR experiments were limited to cryogenic temperatures (TEPR as well as other approaches based on EPR (e.g., relaxation enhancement; RE). In this paper, we review the features of PD EPR and RE at ambient temperatures, in particular, requirements on electron spin phase memory time, ways of immobilization of biomolecules, the influence of a linker between the spin probe and biomolecule, and future opportunities. Copyright © 2017 Elsevier Inc. All rights reserved.

EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment

International Nuclear Information System (INIS)

Shih, Y.H.; Rubin, M.H.; Sergienko, A.V.

1992-01-01

After a very brief review of the historical Einstein, Podolsky, and Rosen (EPR) experiments, a new two-photon interference type EPR experiment is reported. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First and second order interference effectors were studied. Different than other reports, we observed that the second order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences

EPR experiment and 2-photon interferometry: Report of a 2-photon interference experiment

Science.gov (United States)

Shih, Y. H.; Rubin, M. H.; Sergienko, A. V.

1992-01-01

After a very brief review of the historical Einstein, Podolsky, and Rosen (EPR) experiments, a new two-photon interference type EPR experiment is reported. A two-photon state was generated by optical parametric down conversion. Pairs of light quanta with degenerate frequency but divergent directions of propagation were sent to two independent Michelson interferometers. First and second order interference effectors were studied. Different than other reports, we observed that the second order interference visibility vanished when the optical path difference of the interferometers were much less than the coherence length of the pumping laser beam. However, we also observed that the second order interference behaved differently depending on whether the interferometers were set at equal or different optical path differences.

EPR's energy conversion system. Alstom's solutions

International Nuclear Information System (INIS)

Ledermann, P.

2009-01-01

ARABELLE steam turbines have been developed by Alstom to be used as the energy conversion system of light water reactors with high output power like the N4 PWR and the EPR. ARABELLE turbines cumulate 200.000 hours of service with a reliability ratio of 99.97 per cent. This series of slides presents the main features of the turbine including: the use of the simple flux, the very large shape of low pressure blades, the technology of welded rotors. The other main equipment like the alternator, the condenser, the moisture separator-reheaters, the circulating pumps that Alstom integrates in the energy conversion system have benefited with technological improvements that are also presented. (A.C.)

Two-dimensional 220 MHz Fourier transform EPR imaging

International Nuclear Information System (INIS)

Placidi, Giuseppe; Brivati, John A.; Alecci, Marcello; Testa, Luca; Sotgiu, Antonello

1998-01-01

In the last decade radiofrequency continuous-wave EPR spectrometers have been developed to detect and localize free radicals in vivo. Only recently, pulsed radiofrequency EPR spectrometers have been described for imaging applications with small samples. In the present work, we show the first two-dimensional image obtained at 220 MHz on a large phantom (40 ml) that simulates typical conditions of in vivo EPR imaging. This pulsed EPR apparatus has the potential to make the time required for three-dimensional imaging compatible with the biological half-life of normally used paramagnetic probes. (author)

Investigations on resolution enhancement in EPR by means of electron spin echoes

International Nuclear Information System (INIS)

Merks, R.P.J.

1979-01-01

The electron spin echo technique has been applied in four types of experiments: the measurement of electric field induced shifts of the EPR line; the detection of electron spin echo ENDOR; a relaxation measurement and the measurement of hyperfine interactions via the nuclear modulation effect. (Auth.)

EPR design features to mitigate severe accident challenges

International Nuclear Information System (INIS)

Mazurkiewicz, S.M.; Fischer, M.; Bittermann, D.

2005-01-01

The EPR, an evolutionary pressurized water reactor (PWR), is a 4300-4500 MWth that incorporates proven technology within an optimized configuration to enhance safety. EPR was originally developed through a joint effort between Framatome ANP and Siemens by incorporating the best technological features from the French and German nuclear reactor fleets into a cost-competitive product. Commercial EPR units are currently being built in Finland at the Olkiluoto site, and planned for France at the Flamanville site. In recent months, Framatome ANP announced their intention to market the EPR units to China in response to a request for vendor bids as well as their intent to pursue design certification in the United States under 10CFR52. The EPR safety philosophy is based on a deterministic consideration of defense-in-depth complemented by probabilistic analyses. Not only is the EPR designed to prevent and mitigate design basis accidents (DBAs), it employs an extra level of safety associated with severe accident response. Therefore, as a design objective, features are included to ensure that radiological consequences are limited such that the need for stringent counter measures, such as evacuation and relocation of the nearby population, can be reasonably excluded. This paper discusses some of the innovative features of the EPR to address severe accident challenges. (author)

Light-induced defect creation in hydrogenated polymorphous silicon

International Nuclear Information System (INIS)

Morigaki, K.; Takeda, K.; Hikita, H.; Roca i Cabarrocas, P.

2005-01-01

Light-induced defect creation in hydrogenated polymorphous silicon (pm-Si:H) is investigated from electron spin resonance measurements and is compared with that in hydrogenated amorphous silicon (a-Si:H). Light-induced defect creation occurs at room temperature similarly for both types of films prepared at 250 deg. C. Thermal annealing of light-induced defects is also investigated as a function of temperature. Different behaviours of annealing characteristics for pm-Si:H from those for a-Si:H are observed and discussed. In particular, we observed a decrease of the light-induced defect creation efficiency with repeated light-soaking-annealing cycles and discuss it with respect to the hydrogen bonding in pm-Si:H films

Smart Fluid System Dually Responsive to Light and Electric Fields: An Electrophotorheological Fluid.

Science.gov (United States)

Yoon, Chang-Min; Jang, Yoonsun; Noh, Jungchul; Kim, Jungwon; Jang, Jyongsik

2017-10-24

Electrophotorheological (EPR) fluids, whose rheological activity is dually responsive to light and electric fields (E fields), is formulated by mixing photosensitive spiropyran-decorated silica (SP-sSiO 2 ) nanoparticles with zwitterionic lecithin and mineral oil. A reversible photorheological (PR) activity of the EPR fluid is developed via the binding and releasing mechanism of lecithin and merocyanine (MC, a photoisomerized form of SP) under ultraviolet (UV) and visible (VIS) light applications. Moreover, the EPR fluid exhibits an 8-fold higher electrorheological (ER) performance compared to the SP-sSiO 2 nanoparticle-based ER fluid (without lecithin) under an E field, which is attributed to the enhanced dielectric properties facilitated by the binding of the lecithin and SP molecules. Upon dual application of UV light and an E field, the EPR fluid exhibits high EPR performance (ca. 115.3 Pa) that far exceeds its separate PR (ca. 0.8 Pa) and ER (ca. 57.5 Pa) activities, because of the synergistic contributions of the PR and ER effects through rigid and fully connected fibril-like structures. Consequently, this study offers a strategy on formulation of dual-stimuli responsive smart fluid systems.

Light-induced reversible expansion of individual gold nanoplates

Directory of Open Access Journals (Sweden)

Jinsheng Lu

2017-10-01

Full Text Available Light-induced mechanical response of materials has been extensively investigated and widely utilized to convert light energy into mechanical energy directly. The metallic nanomaterials have excellent photothermal properties and show enormous potential in micromechanical actuators, etc. However, the photo-thermo-mechanical properties of individual metallic nanostructures have yet to be well investigated. Here, we experimentally demonstrate a way to realize light-induced reversible expansion of individual gold nanoplates on optical microfibers. The light-induced thermal expansion coefficient is obtained as 21.4 ± 4.6 ∼ 31.5 ± 4.2 μ·K-1 when the light-induced heating temperature of the gold nanoplates is 240 ∼ 490 °C. The photo-thermo-mechanical response time of the gold nanoplates is about 0.3 ± 0.1 s. This insight into the photo-thermo-mechanical properties of the gold nanoplates could deepen the understanding of the light-induced reversible expansion behavior in nanoscale and pave the way for applications based on this piezoelectric-like response, such as light-driven metallic micromotors.

EPR by Areva. The path of greatest certainty

International Nuclear Information System (INIS)

2008-01-01

AREVA's Evolutionary Power Reactor (EPR) is the first Generation III+ reactor design currently being built to answer the world's growing demand for clean and reliable electricity generation. Already under construction in Finland, France and China, the EPR is also being considered by America, United Kingdom, South Africa and other countries for the development of their nuclear fleet. The EPR is now clearly destined to become the mainstay of standardized, efficient reactor fleets around the globe. AREVA's EPR incorporates unbeatable know-how provided by an uninterrupted track record of reactor building activities and backed by decades of feedback experience from operating PWRs, including the most recent. The EPR is a Franco-German initiative which benefited from the stringent scrutiny of safety authorities from both countries, at each stage of the project. The EPR has already secured construction licenses from two of the world's most demanding safety authorities in France and Finland and is currently in line for a design certification and a combined construction and operating license (COL) in the USA. It is also taking part in the licensing process recently launched in the United Kingdom. Europe's leading utilities have granted the EPR their approval under the 'European Utilities Requirements' and have further expressed individual interest in the design and performance of the EPR for their businesses. AREVA is the only Gen III+ reactor constructor in the world with ongoing building experience. To date, AREVA is the only vendor who has the necessary field experience that future customers can benefit: - Detailed design completed; - Experience feedback from 87 PWR; - 3 projects going on; - Continuous PWR experience in design and construction. Close to 100% of the EPR primary circuit heavy components are sourced directly from AREVA's integrated plants. Engineering, manufacturing, services and fuel cycle management are totally integrated and mastered by AREVA. From its

EPR paradox revisited

Energy Technology Data Exchange (ETDEWEB)

Klippert, R. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

1999-07-01

In a seminal paper from 1935 Einstein, Podolsky and Rosen produced one of the most powerful weapon against the unpredictability of the world ensured by quantum mechanics. The recent production of entangled states, with all its possible future applications in quantum computation, re-open the possibility of testing EPR states on physical grounds. The present intends to present a challenge to the wedding of classical (special) relativity with quantum mechanics, the so called relativistic quantum mechanics. Making use of the same apparatus devised in EPR, it is shown that non local quantum states are incompatible with either their possibility of being measured or else with Lorentz invariance (or even with both). (author)

Use of aspartame-based sweetener tablets in emergency dosimetry using EPR.

Science.gov (United States)

Maghraby, A; Salama, E

2010-06-01

Accident dosimetry aims to evaluate the unplanned radiation doses delivered to individuals through one of the objects exist in the area of the accident. The gamma dose response of free radicals generated in irradiated aspartame tablets and its usability for emergency dosimetry was studied. EPR spectra of unirradiated and irradiated aspartame-based sweetener were recorded. Two signals arise after irradiating, S(1) at g (S(1)) = 2.00229 +/- 0.00097 and S(2) at g (S(2)) = 2.00262 +/- 0.00088. Some EPR parameters were studied for radiation-induced radicals in aspartame sweeteners tablets, such as the microwave saturation behaviour, the effect of magnetic field modulation amplitude on the peak-to-peak height and peak-to-peak line width for both of S(1) and S(2). Responses of S(1) and S(2) to different radiation doses were studied and resulted in linear relationships, radicals persistence curves were plotted over a 49-d storage period. It was found that Aspartame sweeteners tablets are useful in the range from 0.96 to 39.96 Gy. Radiation-induced radicals possess reasonable stability.

Investigation of anisotropy in EPR spectra of radiation defects in irradiated beryllium ceramics

International Nuclear Information System (INIS)

Polyakov, A.I.; Ryabikin, Yu.A.; Zashkvara, O. V.; Bitenbaev, M.I.; Petukhov, Yu. V.

2004-01-01

Full text: In this work results of analysis of anisotropy and hyperfine structure in EPR spectra of paramagnetic defects in irradiated samples of beryllium ceramics are presented. To explain peculiarities in a shape and parameters of the EPR spectrum hyperfine structure in beryllium ceramics, we have analyzed several versions of model representations for the radiation-induced paramagnetic defects uniformly distributed in a sample as well as for cluster defects which hyperfine structure is determined by interactions between electrons and nuclei of impurity atoms (S=1/2) and which are characterized by anisotropy in the g factors. Calculations of a shape of the uniformly widened EPR spectra are carried out by the model of random interactions between electron spins. The EPR spectra, widened at the expense of anisotropy in the g factors, are calculated by the following equation: g(Δ)=[2(ω-ω 0 )+α] -1/2 , where ω 0 =γH 0 , α is the quantify proportional to the anisotropy shift. To describe wings of spectral lines, where the equation doesn't work, we use the Gaussian function. To determine the frequency of precession of electron spins packages with local concentration N loc , the following expression is used: ω=ω 0 +1/2α(3cos 2 θ-1), where θ is an angle between the symmetry axis and the direction of the external magnetic field. It is shown that the best agreement between the calculated and experimental EPR spectra is observed with the following computational model: paramagnetic radiation defects are distributed uniformly over a ceramics sample, and the g factors of its EPR spectra have the anisotropy typical for dipole-dipole interaction in powder samples. By results of the data we obtained, it's clear that in future we'll need in more detailed information than that published in scientific journals about formation of the paramagnetic defect EPR spectra structure in beryllium oxides and ceramics at the expense of resonance line hyperfine splitting on atoms of

Investigation of anisotropy in EPR spectra of radiation defects in irradiated beryllium ceramics

Energy Technology Data Exchange (ETDEWEB)

Polyakov, A I; Ryabikin, Yu A; Zashkvara, O V; Bitenbaev, M I; Petukhov, Yu V [Inst. of Physics and Technology, Almaty (Kazakhstan)

2004-07-01

Full text: In this work results of analysis of anisotropy and hyperfine structure in EPR spectra of paramagnetic defects in irradiated samples of beryllium ceramics are presented. To explain peculiarities in a shape and parameters of the EPR spectrum hyperfine structure in beryllium ceramics, we have analyzed several versions of model representations for the radiation-induced paramagnetic defects uniformly distributed in a sample as well as for cluster defects which hyperfine structure is determined by interactions between electrons and nuclei of impurity atoms (S=1/2) and which are characterized by anisotropy in the g factors. Calculations of a shape of the uniformly widened EPR spectra are carried out by the model of random interactions between electron spins. The EPR spectra, widened at the expense of anisotropy in the g factors, are calculated by the following equation: g({delta})=[2({omega}-{omega}{sub 0})+{alpha}]{sup -1/2}, where {omega}{sub 0}={gamma}H{sub 0}, {alpha} is the quantify proportional to the anisotropy shift. To describe wings of spectral lines, where the equation doesn't work, we use the Gaussian function. To determine the frequency of precession of electron spins packages with local concentration N{sub loc}, the following expression is used: {omega}={omega}{sub 0}+1/2{alpha}(3cos{sup 2}{theta}-1), where {theta} is an angle between the symmetry axis and the direction of the external magnetic field. It is shown that the best agreement between the calculated and experimental EPR spectra is observed with the following computational model: paramagnetic radiation defects are distributed uniformly over a ceramics sample, and the g factors of its EPR spectra have the anisotropy typical for dipole-dipole interaction in powder samples. By results of the data we obtained, it's clear that in future we'll need in more detailed information than that published in scientific journals about formation of the paramagnetic defect EPR spectra structure in

The EPR - technology for the 3rd Millennium

International Nuclear Information System (INIS)

Bernstrauch, O.

2000-01-01

The Basic Design of the European Pressurized Water Reactor (EPR) was completed 1997 , the Basic Design Optimization Phase 1998 and the Detailed Design Phase will start in the near future. With these milestones, a new generation of PWRs is moving forward. Most of all, this is another story of a successful Franco-German cooperation. It is a rundown of the history of the EPR, before a decision is made to launch the lead-unit construction. The EPR project was launched in 1992 by Nuclear Power International (NPI), a joint company of FRAMATOME and Siemens KWU, supported by EDF and nine German electric utilities. Each step of the development of the EPR was harmonized with the Nuclear Safety Authorities both in France and Germany to reach an early approval. The EPR integrates the latest technological advances, especially in safety and operational aspects and comprises more than 30 years operating experience. Thus, the EPR combines the qualities of its predecessors, the French N4 and the German Konvoi. Presently, Siemens KWU and FRAMATOME are preparing the detailed design phase and the following construction and commissioning phase. The decision to build an EPR is not yet made either by the German electric utilities or by EdF, but it will be expected within the next months as a strong statement to follow the nuclear way and to ensure the know-how transfer. (author)

POSSIBLE NATURE OF THE RADIATION-INDUCED SIGNAL IN NAILS: HIGH-FIELD EPR, CONFIRMING CHEMICAL SYNTHESIS, AND QUANTUM CHEMICAL CALCULATIONS.

Science.gov (United States)

Tipikin, Dmitriy S; Swarts, Steven G; Sidabras, Jason W; Trompier, François; Swartz, Harold M

2016-12-01

Exposure of finger- and toe-nails to ionizing radiation generates an Electron Paramagnetic Resonance (EPR) signal whose intensity is dose dependent and stable at room temperature for several days. The dependency of the radiation-induced signal (RIS) on the received dose may be used as the basis for retrospective dosimetry of an individual's fortuitous exposure to ionizing radiation. Two radiation-induced signals, a quasi-stable (RIS2) and stable signal (RIS5), have been identified in nails irradiated up to a dose of 50 Gy. Using X-band EPR, both RIS signals exhibit a singlet line shape with a line width around 1.0 mT and an apparent g-value of 2.0044. In this work, we seek information on the exact chemical nature of the radiation-induced free radicals underlying the signal. This knowledge may provide insights into the reason for the discrepancy in the stabilities of the two RIS signals and help develop strategies for stabilizing the radicals in nails or devising methods for restoring the radicals after decay. In this work an analysis of high field (94 GHz and 240 GHz) EPR spectra of the RIS using quantum chemical calculations, the oxidation-reduction properties and the pH dependence of the signal intensities are used to show that spectroscopic and chemical properties of the RIS are consistent with a semiquinone-type radical underlying the RIS. It has been suggested that semiquinone radicals formed on trace amounts of melanin in nails are the basis for the RIS signals. However, based on the quantum chemical calculations and chemical properties of the RIS, it is likely that the radicals underlying this signal are generated from the radiolysis of L-3,4-dihydroxyphenylalanine (DOPA) amino acids in the keratin proteins. These DOPA amino acids are likely formed from the exogenous oxidation of tyrosine in keratin by the oxygen from the air prior to irradiation. We show that these DOPA amino acids can work as radical traps, capturing the highly reactive and unstable sulfur

Dental radiography: tooth enamel EPR dose assessment from Rando phantom measurements

International Nuclear Information System (INIS)

Aragno, D.; Fattibene, P.; Onori, S.

2000-01-01

Electron paramagnetic resonance dosimetry of tooth enamel is now established as a suitable method for individual dose reconstruction following radiation accidents. The accuracy of the method is limited by some confounding factors, among which is the dose received due to medical x-ray irradiation. In the present paper the EPR response of tooth enamel to endoral examination was experimentally evaluated using an anthropomorphic phantom. The dose to enamel for a single exposure of a typical dental examination performed with a new x-ray generation unit working at 65 kVp gave rise to a CO 2 -signal of intensity similar to that induced by a dose of about 2 mGy of 60 Co. EPR measurements were performed on the entire tooth with no attempt to separate buccal and lingual components. Also the dose to enamel for an orthopantomography exam was estimated. It was derived from TLD measurements as equivalent to 0.2 mGy of 60 Co. In view of application to risk assessment analysis, in the present work the value for the ratio of the reference dose at the phantom surface measured with TLD to the dose at the tooth measured with EPR was determined. (author)

Camel molar tooth enamel response to gamma rays using EPR spectroscopy.

Science.gov (United States)

El-Faramawy, N A; El-Somany, I; Mansour, A; Maghraby, A M; Eissa, H; Wieser, A

2018-03-01

Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH pp ) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry.

Camel molar tooth enamel response to gamma rays using EPR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

El-Faramawy, N.A.; El-Somany, I. [Ain Shams University, Physics Department, Faculty of Science, Cairo (Egypt); Mansour, A. [National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo (Egypt); Maghraby, A.M.; Eissa, H. [National Institute of Standards (NIS), Ionizing Radiation Metrology Laboratory, Giza (Egypt); Wieser, A. [Helmholtz Zentrum Muenchen-German Research Center for Environmental Health, Department of Radiation Sciences, Institute of Radiation Protection, Neuherberg (Germany)

2018-03-15

Tooth enamel samples from molar teeth of camel were prepared using a combined procedure of mechanical and chemical tooth treatment. Based on electron paramagnetic resonance (EPR) spectroscopy, the dose response of tooth enamel samples was examined and compared to that of human enamel. The EPR dose response of the tooth enamel samples was obtained through irradiation to gamma doses from 1 Gy up to 100 kGy. It was found that the radiation-induced EPR signal increased linearly with gamma dose for all studied tooth enamel samples, up to about 15 kGy. At higher doses, the dose response curve leveled off. The results revealed that the location of the native signal of camel tooth enamel was similar to that of enamel from human molars at 2.00644, but different from that of enamel from cows and goats. In addition, the peak-to-peak width (ΔH{sub pp}) for human and camel molar teeth was similar. It was also found that the response of camel enamel to gamma radiation was 36% lower than that of human enamel. In conclusion, the results indicate the suitability of camel teeth for retrospective gamma dosimetry. (orig.)

Experimental EPR-steering using Bell-local states

Science.gov (United States)

Saunders, D. J.; Jones, S. J.; Wiseman, H. M.; Pryde, G. J.

2010-11-01

The concept of `steering' was introduced in 1935 by Schrödinger as a generalization of the EPR (Einstein-Podolsky-Rosen) paradox. It has recently been formalized as a quantum-information task with arbitrary bipartite states and measurements, for which the existence of entanglement is necessary but not sufficient. Previous experiments in this area have been restricted to an approach that followed the original EPR argument in considering only two different measurement settings per side. Here we demonstrate experimentally that EPR-steering occurs for mixed entangled states that are Bell local (that is, that cannot possibly demonstrate Bell non-locality). Unlike the case of Bell inequalities, increasing the number of measurement settings beyond two-we use up to six-significantly increases the robustness of the EPR-steering phenomenon to noise.

EPR dosimetry of glass substrate of mobile phone LCDs

International Nuclear Information System (INIS)

Trompier, F.; Della Monaca, S.; Fattibene, P.; Clairand, I.

2011-01-01

Previous studies have shown that mineral glass from watches, windows and displays of personal electronic devices could be a suitable restrospective dosimeter in case of radiation accident. In this paper glass substrates of the window display of 100 mobile phones of different trademarks were analized by X-band cw-EPR before and after irradiation at 100 Gy. The objective of this study was to highlight some issues of EPR measurements of glass related to inter-sample variability of: i) signal line shape in irradiated and unirradiated glass; ii) signal intensity loss and line shape change with post-irradiation time; iii) signal changes induced by sample preparation and iv) signal changes induced by thermal annealing. Scope of the paper is to provide a phenomenological picture of the observed effects in order to give a warning about possible problems and to provide suggestions for future work. Explanation of the mechanisms and the causes leading to the observed effects was beyond the scope of this work. These preliminary results confirm that glass substrate of mobile phone displays should be considered as a fortuitous dosimeter in radiation accidents. However, albeit very promising, mineral glass presents a number of issues that should be thoroughly investigated and addressed in future work.

Identification of irradiated oysters by EPR measurements on shells

International Nuclear Information System (INIS)

Della Monaca, S.; Fattibene, P.; Boniglia, C.; Gargiulo, R.; Bortolin, E.

2011-01-01

In this paper the EPR spectra of the radicals induced in oyster shells after irradiation to (0.5-2) kGy ionizing radiation doses are analyzed. EPR spectra of irradiated shells showed the complex radical composition of biocarbonates, characterized by the presence of SO 2 - , SO 3 - and CO 2 - radicals with different symmetries. In particular, the radiation-induced line at g = 2.0038, due to the g x component of the orthorhombic SO 3 - , was well distinguishable from the rest of the spectrum. The g x component of the orthorhombic SO 3 - was found to be intense and stable enough to allow the identification at least for the whole shelf life of the oyster. Furthermore, it is still well visible at low microwave powers for which the other signals are weak or non-visible and has a linear dose response in the (0.5-2) kGy range. A possible procedure protocol for the identification of irradiated oysters, can be based on acquisitions of the spectrum at low microwave power values (tenths of milliWatt) and low modulation amplitude values (0.03-0.05 mT) and on the identification of the g = 2.0038 signal as a proof of the ionizing radiation treatment performed on the sample.

Stability of X-band EPR signals from fingernails under vacuum storage.

Science.gov (United States)

Sholom, Sergey; McKeever, Stephen

2017-12-01

EPR signals of different origin have been tested in human finger- and toe-nails with an X-band EPR technique for different conditions of nail storage. Three different signals were identified, namely a singlet at g=2.005, a doublet at g=2.004 with a splitting constant A=1.8 mT, and an anisotropic signal at g1=2.057, g2=2.029 and g3=2.003 (positions of local extrema). All EPR spectra from nails, whether irradiated or mechanically stressed, can be described as a superposition of these three signals. The singlet is responsible for the background signal (BG), is the main component of radiation-induced signals (RIS) for low doses (100 Gy or lower) and also contributes to mechanically-induced signals (MIS). This signal is quite stable under vacuum storage, but can be reduced almost to zero by soaking in water. The behavior of this signal under ambient conditions depends on many factors, such as absorbed dose, air humidity, and ambient illumination intensity at the place of storage. The doublet arises after exposure of nails to high (few hundreds Gy and higher) doses or after mechanical stress of samples. Depending on how this signal was obtained, it may have bulk or surface locations with quite different stability properties. The surface-located doublet (generated on the nail edges during cutting or clipping) is quite unstable and decays over about two hours for samples stored at ambient conditions and within several seconds for samples immersed in water. The volume-distributed doublet decays within a few minutes in water, several hours at ambient conditions and several days in vacuum. The anisotropic signal may also be generated by both ionizing radiation and mechanical stress; this signal is quite stable in vacuum and decays over several days at ambient conditions or a few tens of minutes in water. The reference lines for the above-described three EPR signals were obtained and a procedure of spectra deconvolution was developed and tested on samples exposed to both

EPR by Areva. The path of greatest certainty

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-07-01

AREVA's Evolutionary Power Reactor (EPR) is the first Generation III+ reactor design currently being built to answer the world's growing demand for clean and reliable electricity generation. Already under construction in Finland, France and China, the EPR is also being considered by America, United Kingdom, South Africa and other countries for the development of their nuclear fleet. The EPR is now clearly destined to become the mainstay of standardized, efficient reactor fleets around the globe. AREVA's EPR incorporates unbeatable know-how provided by an uninterrupted track record of reactor building activities and backed by decades of feedback experience from operating PWRs, including the most recent. The EPR is a Franco-German initiative which benefited from the stringent scrutiny of safety authorities from both countries, at each stage of the project. The EPR has already secured construction licenses from two of the world's most demanding safety authorities in France and Finland and is currently in line for a design certification and a combined construction and operating license (COL) in the USA. It is also taking part in the licensing process recently launched in the United Kingdom. Europe's leading utilities have granted the EPR their approval under the 'European Utilities Requirements' and have further expressed individual interest in the design and performance of the EPR for their businesses. AREVA is the only Gen III+ reactor constructor in the world with ongoing building experience. To date, AREVA is the only vendor who has the necessary field experience that future customers can benefit: - Detailed design completed; - Experience feedback from 87 PWR; - 3 projects going on; - Continuous PWR experience in design and construction. Close to 100% of the EPR primary circuit heavy components are sourced directly from AREVA's integrated plants. Engineering, manufacturing, services and fuel cycle management are totally

Correlations between the particles in the EPR-paradox

Energy Technology Data Exchange (ETDEWEB)

Treder, H.J. (Akademie der Wissenschaften der DDR, Potsdam-Babelsberg. Einstein-Laboratorium fuer Theoretische Physik)

1984-03-01

The Einstein-Podolsky-Rosen 'gedanken-experiment' does not imply non-local interactions or an 'action-at-a-distance'. Contrary, the EPR proves the measurements at one particle does not have influences at canonical variables of the other particles if the quantum-mechanical commutation relations are true. But, the EPR implies correlations between the particles which come in by 'subjective knowledge'. These correlations are a priori informations about the relative motion or, complementarily, about the motion of the center of mass. The impression of an action-at-a-distance is produced by the use of usual particle coordinates in the EPR-arrangements. The discussion of the Einstein-Podolsky-Rosen 'gedanken-experiment' (EPR) has been going on over fifty years. Einstein, Podolsky, and Rosen formulated their famous paradox in 1935, and in the discussion between N. Bohr (1935, 1949) and Einstein (1936, 1948); A. Einstein (1948) made his point that the EPR implied an 'action-at-a-distance' for quantum-mechanical particles (without obvious classical interactions). His argument is the starting point for the recent discussion about EPR and causality (see A. Aspect 1981).

EPR-technical codes - a common basis for the EPR

International Nuclear Information System (INIS)

Zaiss, W.; Appell, B.

1997-01-01

The design and construction of Nuclear Power Plants implies a full set of codes and standards to define the construction rules of components and equipment. Rules are existing and are currently implemented, respectively in France and Germany (mainly RCCs and KTA safety standards). In the frame of the EPR-project, the common objective requires an essential industrial work programme between engineers from both countries to elaborate a common set of codes and regulations. These new industrial rules are called the ETCs (EPR Technical Codes). In the hierarchy the ETCs are - in case of France - on the common level of basic safety rules (RFS), design and construction rules (RCC) and - in Germany - belonging to RSK guidelines and KTA safety standards. A set of six ETCs will be elaborated to cover: safety and process, mechanical components, electrical equipment, instrumentation and control, civil works, fire protection. (orig.)

A web-based database for EPR centers in semiconductors

International Nuclear Information System (INIS)

Umeda, T.; Hagiwara, S.; Katagiri, M.; Mizuochi, N.; Isoya, J.

2006-01-01

We develop a web-based database system for electron paramagnetic resonance (EPR) centers in semiconductors. This database is available to anyone at http://www.kc.tsukuba.ac.jp/div-media/epr/. It currently has more than 300 records of the spin-Hamiltonian parameters for major known EPR centers. One can upload own new records to the database or can use simulation tools powered by EPR-NMR(C). Here, we describe the features and objectives of this database, and mention some future plans

Heavy-ion-induced sucrose radicals investigated using EPR and UV spectroscopy

Science.gov (United States)

Nakagawa, Kouichi; Karakirova, Yordanka; Yordanov, Nicola D.

2015-01-01

The potential use of a sucrose dosimeter for estimating both linear energy transfer (LET) and the absorbed dose of heavy ion and X-ray radiation was investigated. The stable free radicals were produced when sucrose was irradiated with heavy ions, such as helium, carbon, silicon and neon ions, and when the X-ray radiation was similar to the obtained electron paramagnetic resonance (EPR) spectra, which were ∼7 mT wide and composed of several hyperfine structures. In addition, the total spin concentration resulting from heavy-ion irradiation increased linearly as the absorbed dose increased, and decreased logarithmically as the LET increased. These empirical relations imply that the LET at a certain dose can be determined from the spin concentration. For sucrose and alanine, both cross-sections following C-ion irradiation with a 50 Gy dose were ∼1.3 × 10−12 [μm2], taking into account the molecular size of the samples. The values of these cross-sections imply that multiple ionizing particles were involved in the production of stable radicals. Furthermore, UV absorbance at 267 nm of an aqueous solution of irradiated sucrose was found to linearly increase with increasing absorbed dose. Therefore, the EPR and UV results suggest that sucrose can be a useful dosimeter for heavy-ion irradiation. PMID:25480828

High-frequency EPR on high-spin transition-metal sites

NARCIS (Netherlands)

Mathies, Guinevere

2012-01-01

The electronic structure of transition-metal sites can be probed by electron-paramagnetic-resonance (EPR) spectroscopy. The study of high-spin transition-metal sites benefits from EPR spectroscopy at frequencies higher than the standard 9.5 GHz. However, high-frequency EPR is a developing field. In

Physically-based biodosimetry using in vivo EPR of teeth in patients undergoing total body irradiation

Science.gov (United States)

Williams, Benjamin B.; Dong, Ruhong; Nicolalde, Roberto J.; Matthews, Thomas P.; Gladstone, David J.; Demidenko, Eugene; Zaki, Bassem I.; Salikhov, Ildar K.; Lesniewski, Piotr N.; Swartz, Harold M.

2014-01-01

Purpose The ability to estimate individual exposures to radiation following a large attack or incident has been identified as a necessity for rational and effective emergency medical response. In vivo electron paramagnetic resonance (EPR) spectroscopy of tooth enamel has been developed to meet this need. Materials and methods A novel transportable EPR spectrometer, developed to facilitate tooth dosimetry in an emergency response setting, was used to measure upper incisors in a model system, in unirradiated subjects, and in patients who had received total body doses of 2 Gy. Results A linear dose response was observed in the model system. A statistically significant increase in the intensity of the radiation-induced EPR signal was observed in irradiated versus unirradiated subjects, with an estimated standard error of dose prediction of 0.9 + 0.3 Gy. Conclusions These results demonstrate the current ability of in vivo EPR tooth dosimetry to distinguish between subjects who have not been irradiated and those who have received exposures that place them at risk for acute radiation syndrome. Procedural and technical developments to further increase the precision of dose estimation and ensure reliable operation in the emergency setting are underway. With these developments EPR tooth dosimetry is likely to be a valuable resource for triage following potential radiation exposure of a large population. PMID:21696339

EPR Dosimetry for ageing effect in NPP

International Nuclear Information System (INIS)

Choi, Hoon; Lim, Young Ki; Kim, Jong Seog; Jung, Sun Chul

2005-01-01

As one of the retrospective dosimetry method, EPR spectroscopy has been studied by many research up to theses days. As a dosimeter for EPR spectroscopy, Alanine is already a well known dosimeter in the field of radiation therapy and dose assessment in radiological accident by its characteristics as good linearity in a wide range of energy level and extremely low signal fading on time. Through technical document of IAEA, the EPR dosimetry method using alanine sample was published in 2000 after research by coordinated project on management of ageing of in-containment I and C cables. Although alanine sample is regarded as a good EPR dosimeter like above ageing assessment field, actually the assessment of radiation should be done at least for two fuel cycles, because of its relatively low irradiation environment in almost all spots in power plant. So, for getting more accurate detection value of radiation, another material is tested for being put in simultaneously inside the power plant with alanine. The test result for lithium formate monohydrate (HCO 2 LiH 2 0) was presented below for checking its possibility for being applied as EPR dosimeter for this project

EPR and development of quantum electronics

International Nuclear Information System (INIS)

Manenkov, A A

2011-01-01

A role of electron paramagnetic resonance in development of quantum electronics is discussed. Basic principles and history of masers are briefly described. Spin-levels of paramagnetic ions in crystals as a very suitable object for active media of solid-state masers (called as EPR-masers) and physical processes in EPR-masers (population inversion of energy states) are analyzed. This analysis demonstrates a significant role of relaxation processes in multi-level spin-systems for efficient maser action. In this context peculiarities of spin-lattice and spin-spin cross relaxation processes in multi-level systems are analyzed. Development of EPR-masers and their application in radioastronomy and far-space communication systems are briefly described.

Assessment of performance parameters for EPR dosimetry with tooth enamel

International Nuclear Information System (INIS)

Wieser, A.; Fattibene, P.; Shishkina, E.A.; Ivanov, D.V.; De Coste, V.; Guettler, A.; Onori, S.

2008-01-01

In the framework of a comparison between three laboratories, electron paramagnetic resonance (EPR) signal-to-dose response curves were measured for sets of 30 tooth enamel samples and the variance of EPR measurements in dependence on absorbed dose was evaluated, in nine combinations of laboratory of sample preparation and EPR evaluation, respectively. As a test for benchmarking of EPR evaluation, the parameters 'critical dose' and 'limit of detection' were proposed as performance parameters following definitions from chemical-metrology, and a model function was suggested for analytical formulation of the dependence of the variance of EPR measurement on absorbed dose. First estimates of limits of detection by weighted and unweighted fitting resulted in the range 101-552 and 67-561 mGy, respectively, and were generally larger with weighted than with unweighted fitting. Indication was found for the influence of methodology of sample preparation and applied EPR measurement parameters on performance of EPR dosimetry with tooth enamel

Costing the EPR Project Using the Real Options Method

International Nuclear Information System (INIS)

Epaulard, Anne; Gallon, Stephane

2001-01-01

Real options theory makes it possible to cost investments which offer flexibility but whose returns are uncertain, such as the construction in 2000 of an EPR prototype; this prototype will enable the European pressurised-water reactor (EPR) to be used to renew EDF's nuclear power stations in 2020 (flexibility) but its economic worth will then depend on the cost of the competing gas-fired power plants (uncertain return). Options theory shows that investing in EPR technology in 2000 provides sufficient flexibility in 2020 to be considered cost-effective, even though use of EPRs is unlikely by that date. The investment made in 2000 to develop EPR technology therefore actually plays the part of an option or, in other words, insurance (against the risk of high gas prices)

EPR: the nuclear impasse; EPR: l'impasse nucleaire

Energy Technology Data Exchange (ETDEWEB)

Marillier, F [Association Ecologiste Greenpeace (France)

2008-07-01

The questions relative to the climatic change constitute crucial challenges for the next ten years. In this context the author aims to show how the EPR project illustrates the nuclear french ''autism''. He presents and analyzes the international and environmental impacts of this obsolete technology, as a project useless and dangerous. (A.L.B.)

Effect of UV irradiation on Echinaceae purpureae interactions with free radicals examined by an X-band (9.3 GHz) EPR spectroscopy.

Science.gov (United States)

Ramos, Paweł; Pilawa, Barbara

The effect of UVA (315-400 nm) irradiation on Echinaceae purpureae interactions with free radicals was examined by the use of electron paramagnetic resonance (EPR) spectroscopy. The changes of antioxidant properties of E. purpureae with time of UV irradiation from 10 to 110 min (10 min steps) were determined. DPPH as the paramagnetic reference was used in this study. Changes of EPR signals of the reference after interactions with nonirradiated and UV-irradiated E. purpureae were detected. Interactions of the tested E. purpureae samples caused decrease of the EPR signal of DPPH as the result of its antioxidant properties. The decrease of the amplitude of EPR line of DPPH was lower for interactions with UV-irradiated E. purpureae . EPR examination confirmed antioxidant properties of E. purpureae . The weaker antioxidant properties of E. purpureae after UV irradiation were pointed out. E. purpureae should be storage in the dark. The tests bring to light usefulness of electron paramagnetic resonance with microwave frequency of 9.3 GHz (an X-band) in examination of storage conditions of pharmacological herbs.

Nuclear spin-lattice relaxation in nitroxide spin-label EPR.

Science.gov (United States)

Marsh, Derek

2016-11-01

Nuclear relaxation is a sensitive monitor of rotational dynamics in spin-label EPR. It also contributes competing saturation transfer pathways in T 1 -exchange spectroscopy, and the determination of paramagnetic relaxation enhancement in site-directed spin labelling. A survey shows that the definition of nitrogen nuclear relaxation rate W n commonly used in the CW-EPR literature for 14 N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14 N spin-lattice relaxation rate, b=W n /(2W e ), preserves the expressions used for CW-EPR, whilst rendering them consistent with expressions for saturation recovery rates in pulsed EPR. Furthermore, values routinely quoted for nuclear relaxation times that are deduced from EPR spectral diffusion rates in 14 N-nitroxyl spin labels do not accord with conventional analysis of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14 N-relaxation: T 1 n =1/W n . Results are compared and contrasted with those for the two-level 15 N-nitroxide system. Copyright © 2016 Elsevier Inc. All rights reserved.

EPR spectroscopy for the detection of foods treated with ionising radiation

International Nuclear Information System (INIS)

Stachowicz, W.; Burlinska, G.; Michalik, J.; Dziedzic-Goclawska, A.; Ostrowski, K.

1996-01-01

The advantage of electron paramagnetic resonance spectroscopy (EPR or ESR) as a tool for the control of irradiated food lies in its sensitivity and accuracy. Ionising radiation produces, in irradiated materials, paramagnetic species of different kinds, i.e. radicals, radical-ions and paramagnetic centres, which can be measured by EPR but most of them are not stable enough to be used for the detection of irradiation. It is because radiation-induced paramagnetic species are thermodynamically less stable than surrounding molecules and take part in fast radiolytic reactions leading to the formation of final diamagnetic products that they are not detectable by the EPR method. Most of organic radicals produced by radiation in the liquid phase ae unstable but if the unpaired electron is incorporated into the complex polymeric system as in peptides and polysaccharides and is structurally isolated from the water, its stability is markedly increased. Since 1954 it is known that ionising radiation produces paramagnetic entities in biological materials, cells and tissues and some are stable enough to be observed by EPR spectroscopy at room temperature. The present paper describes and discusses that part of results obtained by this group during the period of ADMIT activity (1989-94) which are original and may be useful to those who will be working in the near future on the development of uniform control systems for the detection of irradiated food. The intention was to focus attention on these facts and data which influence the certainty of the detection in both positive and negative manner. (author)

Orientation-dependent effects of EPR-measurements on β-rhombohedral boron

International Nuclear Information System (INIS)

Siems, C.D.; Geist, D.

1976-01-01

EPR studies on β-rhombohedral boron have been reported by several authors. Two EPR-lines with the same g-value have been found by measurements with and without illumination. The microwave frequency used was 9 GHz, as far as is known. In this paper EPR-measurements at 35 GHz on β-rhombohedral boron single crystals are reported. The investigations concerning the 'dark EPR-line' were made at 300 K. (Auth.)

CW EPR and 9 GHz EPR imaging investigation of stable paramagnetic species and their antioxidant activities in dry shiitake mushroom (Lentinus edodes).

Science.gov (United States)

Nakagawa, Kouichi; Hara, Hideyuki

2016-01-01

We investigated the antioxidant activities and locations of stable paramagnetic species in dry (or drying) shiitake mushroom (Lentinus edodes) using continuous wave (CW) electron paramagnetic resonance (EPR) and 9 GHz EPR imaging. CW 9 GHz EPR detected paramagnetic species (peak-to-peak linewidth (ΔHpp) = 0.57 mT) in the mushroom. Two-dimensional imaging of the sharp line using a 9 GHz EPR imager showed that the species were located in the cap and shortened stem portions of the mushroom. No other location of the species was found in the mushroom. However, radical locations and concentrations varied along the cap of the mushroom. The 9 GHz EPR imaging determined the exact location of stable paramagnetic species in the shiitake mushroom. Distilled water extracts of the pigmented cap surface and the inner cap of the mushroom showed similar antioxidant activities that reduced an aqueous solution of 0.1 mM 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl. The present results suggest that the antioxidant activities of the edible mushroom extracts are much weaker than those of ascorbic acid. Thus, CW EPR and EPR imaging revealed the location and distribution of stable paramagnetic species and the antioxidant activities in the shiitake mushroom for the first time.

Relativistic Nonlocality and the EPR Paradox

Science.gov (United States)

Chamberlain, Thomas

2014-03-01

The exact violation of Bell's Inequalities is obtained with a local realistic model for spin. The model treats one particle that comprises a quantum ensemble and simulates the EPR data one coincidence at a time as a product state. Such a spin is represented by operators σx , iσy ,σz in its body frame rather than the usual set of σX ,σY ,σZ in the laboratory frame. This model, assumed valid in the absence of a measuring probe, contains both quantum polarizations and coherences. Each carries half the EPR correlation, but only half can be measured using coincidence techniques. The model further predicts the filter angles that maximize the spin correlation in EPR experiments.

EPR: Some History and Clarification

Science.gov (United States)

Fine, Arthur

2002-04-01

Locality, separation and entanglement 1930s style. We’ll explore the background to the 1935 paper by Einstein, Podolsky and Rosen, how it was composed, the actual argument of the paper, the principles used, and how the paper was received by Schroedinger, and others.We’ll also look at Bohr’s response: the extent to which Bohr connects with what Einstein was after in EPR and the extent to EPR marks a shift in Bohr’s thinking about the quantum theory.

Chirp echo Fourier transform EPR-detected NMR.

Science.gov (United States)

Wili, Nino; Jeschke, Gunnar

2018-04-01

A new ultra-wide band (UWB) pulse EPR method is introduced for observing all nuclear frequencies of a paramagnetic center in a single shot. It is based on burning spectral holes with a high turning angle (HTA) pulse that excites forbidden transitions and subsequent detection of the hole pattern by a chirp echo. We term this method Chirp Echo Epr SpectroscopY (CHEESY)-detected NMR. The approach is a revival of FT EPR-detected NMR. It yields similar spectra and the same type of information as electron-electron double resonance (ELDOR)-detected NMR, but with a multiplex advantage. We apply CHEESY-detected NMR in Q band to nitroxides and correlate the hyperfine spectrum to the EPR spectrum by varying the frequency of the HTA pulse. Furthermore, a selective π pulse before the HTA pulse allows for detecting hyperfine sublevel correlations between transitions of one nucleus and for elucidating the coupling regime, the same information as revealed by the HYSCORE experiment. This is demonstrated on hexaaquamanganese(II). We expect that CHEESY-detected NMR is generally applicable to disordered systems and that our results further motivate the development of EPR spectrometers capable of coherent UWB excitation and detection, especially at higher fields and frequencies. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

Chirp echo Fourier transform EPR-detected NMR

Science.gov (United States)

Wili, Nino; Jeschke, Gunnar

2018-04-01

A new ultra-wide band (UWB) pulse EPR method is introduced for observing all nuclear frequencies of a paramagnetic center in a single shot. It is based on burning spectral holes with a high turning angle (HTA) pulse that excites forbidden transitions and subsequent detection of the hole pattern by a chirp echo. We term this method Chirp Echo Epr SpectroscopY (CHEESY)-detected NMR. The approach is a revival of FT EPR-detected NMR. It yields similar spectra and the same type of information as electron-electron double resonance (ELDOR)-detected NMR, but with a multiplex advantage. We apply CHEESY-detected NMR in Q band to nitroxides and correlate the hyperfine spectrum to the EPR spectrum by varying the frequency of the HTA pulse. Furthermore, a selective π pulse before the HTA pulse allows for detecting hyperfine sublevel correlations between transitions of one nucleus and for elucidating the coupling regime, the same information as revealed by the HYSCORE experiment. This is demonstrated on hexaaquamanganese(II). We expect that CHEESY-detected NMR is generally applicable to disordered systems and that our results further motivate the development of EPR spectrometers capable of coherent UWB excitation and detection, especially at higher fields and frequencies.

Blue light-induced oxidative stress in live skin.

Science.gov (United States)

Nakashima, Yuya; Ohta, Shigeo; Wolf, Alexander M

2017-07-01

Skin damage from exposure to sunlight induces aging-like changes in appearance and is attributed to the ultraviolet (UV) component of light. Photosensitized production of reactive oxygen species (ROS) by UVA light is widely accepted to contribute to skin damage and carcinogenesis, but visible light is thought not to do so. Using mice expressing redox-sensitive GFP to detect ROS, blue light could produce oxidative stress in live skin. Blue light induced oxidative stress preferentially in mitochondria, but green, red, far red or infrared light did not. Blue light-induced oxidative stress was also detected in cultured human keratinocytes, but the per photon efficacy was only 25% of UVA in human keratinocyte mitochondria, compared to 68% of UVA in mouse skin. Skin autofluorescence was reduced by blue light, suggesting flavins are the photosensitizer. Exposing human skin to the blue light contained in sunlight depressed flavin autofluorescence, demonstrating that the visible component of sunlight has a physiologically significant effect on human skin. The ROS produced by blue light is probably superoxide, but not singlet oxygen. These results suggest that blue light contributes to skin aging similar to UVA. Copyright © 2017 Elsevier Inc. All rights reserved.

EPR study on gamma-irradiated fruits dehydrated via osmosis

International Nuclear Information System (INIS)

Yordanov, N.D.; Aleksieva, K.

2007-01-01

The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and γ-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas γ-irradiated exhibit 'sugar-like' EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples

EPR study on gamma-irradiated fruits dehydrated via osmosis

Science.gov (United States)

Yordanov, N. D.; Aleksieva, K.

2007-06-01

The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and γ-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas γ-irradiated exhibit "sugar-like" EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples.

Use of aspartame-based sweetener tablets in emergency dosimetry using EPR

International Nuclear Information System (INIS)

Maghraby, A.; Salama, E.

2010-01-01

Accident dosimetry aims to evaluate the unplanned radiation doses delivered to individuals through one of the objects exist in the area of the accident. The gamma dose response of free radicals generated in irradiated aspartame tablets and its usability for emergency dosimetry was studied. EPR spectra of unirradiated and irradiated aspartame-based sweetener were recorded. Two signals arise after irradiating, S 1 at g (S 1 ) = 2.00229 ± 0.00097 and S 2 at g (S 2 ) = 2.00262 ± 0.00088. Some EPR parameters were studied for radiation-induced radicals in aspartame sweeteners tablets, such as the microwave saturation behaviour, the effect of magnetic field modulation amplitude on the peak-to-peak height and peak-to-peak line width for both of S 1 and S 2 . Responses of S 1 and S 2 to different radiation doses were studied and resulted in linear relationships, radicals persistence curves were plotted over a 49-d storage period. It was found that Aspartame sweeteners tablets are useful in the range from 0.96 to 39.96 Gy. Radiation-induced radicals possess reasonable stability. (authors)

Investigation of EPR signals on tooth enamel

Energy Technology Data Exchange (ETDEWEB)

Pavlenko, A; Mironova-Ulmane, N; Polakov, M; Riekstina, D [Institute of Solid State Physics, University of Latvia, Riga (Latvia)

2007-12-15

Calcified tissues are involved in continues metabolic process in human organism exchanging a number of chemical elements with environment. The rate of biochemical reactions is tissue dependent and the slowest one at the tooth enamel, the most mineralized tissue of human organism. The long time stability and unique chemical composition make tooth enamel suitable for number of application. The assessment of individual radiation dose by Electron Paramagnetic Resonance (EPR) and evaluations of elemental composition by Instrumentation Neutron Activation Analysis (INAA) are the well known procedures where properties of tooth enamel intensively used. The current work is focused on investigation of EPR signals and determination of chemical composition on several teeth samples having different origin. The EPR spectra and INAA element content of milk tooth, caries tooth, and paradantose tooth have been compared to each other. The results showed that the intensity of EPR signal is much higher for the caries tooth than the for paradantose tooth that is in agreement with depleted Ca content.

EPR Spectroscopy in Environmental Lichen-Indication

Science.gov (United States)

Bondarenko, P. V.; Nguyet, Le Thi Bich; Zhuravleva, S. E.; Trukhan, E. M.

2017-09-01

The paramagnetic properties of lichens were investigated using EPR spectroscopy and Xanthoria parietina (L.) Th. Fr. as a case study. It was found that the concentration of paramagnetic centers in lichen thalli increased as the air-pollution level increased. Possible formation mechanisms of the paramagnetic centers in lichens were discussed. The efficiency of using EPR spectroscopy to study lichens as environmental quality indicators was demonstrated.

Identification of irradiated oysters by EPR measurements on shells

Energy Technology Data Exchange (ETDEWEB)

Della Monaca, S., E-mail: sara.dellamonaca@iss.it [Istituto Superiore di Sanita, viale Regina Elena, 299 Rome (Italy); Fattibene, P.; Boniglia, C.; Gargiulo, R.; Bortolin, E. [Istituto Superiore di Sanita, viale Regina Elena, 299 Rome (Italy)

2011-09-15

In this paper the EPR spectra of the radicals induced in oyster shells after irradiation to (0.5-2) kGy ionizing radiation doses are analyzed. EPR spectra of irradiated shells showed the complex radical composition of biocarbonates, characterized by the presence of SO{sub 2}{sup -}, SO{sub 3}{sup -} and CO{sub 2}{sup -} radicals with different symmetries. In particular, the radiation-induced line at g = 2.0038, due to the g{sub x} component of the orthorhombic SO{sub 3}{sup -}, was well distinguishable from the rest of the spectrum. The g{sub x} component of the orthorhombic SO{sub 3}{sup -} was found to be intense and stable enough to allow the identification at least for the whole shelf life of the oyster. Furthermore, it is still well visible at low microwave powers for which the other signals are weak or non-visible and has a linear dose response in the (0.5-2) kGy range. A possible procedure protocol for the identification of irradiated oysters, can be based on acquisitions of the spectrum at low microwave power values (tenths of milliWatt) and low modulation amplitude values (0.03-0.05 mT) and on the identification of the g = 2.0038 signal as a proof of the ionizing radiation treatment performed on the sample.

In vivo EPR extracellular pH-metry in tumors using a triphosphonated trityl radical.

Science.gov (United States)

Marchand, Valérie; Levêque, Philippe; Driesschaert, Benoit; Marchand-Brynaert, Jacqueline; Gallez, Bernard

2017-06-01

The ability to assess the extracellular pH (pHe) is an important issue in oncology, because extracellular acidification is associated with tumor aggressiveness and resistance to cytotoxic therapies. In this study, a stable triphosphonated triarylmethyl (TPTAM) radical was qualified as a pHe electron paramagnetic resonance (EPR) molecular reporter. Calibration of hyperfine splitting as a function of pH was performed using a 1.2-GHz EPR spectrometer. Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) was used as an extracellular paramagnetic broadening agent to assess the localization of TPTAM when incubated with cells. In vivo EPR pH-metry was performed in MDA, SiHa, and TLT tumor models and in muscle. Bicarbonate therapy was used to modulate the tumor pHe. EPR measurements were compared with microelectrode readouts. The hyperfine splitting of TPTAM was strongly pH-dependent around the pKa of the probe (pKa = 6.99). Experiments with Gd-DTPA demonstrated that TPTAM remained in the extracellular compartment. pHe was found to be more acidic in the MDA, SiHa, and TLT tumor models compared with muscle. Treatment of animals by bicarbonate induced an increase in pHe in tumors: similar variations in pHe were found when using in vivo EPR or invasive microelectrodes measurements. This study demonstrates the potential usefulness of TPTAM for monitoring pHe in tumors. Magn Reson Med 77:2438-2443, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Most advanced HTP fuel assembly design for EPR

International Nuclear Information System (INIS)

Francillon, Eric; Kiehlmann, Horst-Dieter

2006-01-01

End 2003, the Finnish electricity utility Teollisuuden Voima Oy (TVO) signed the contract for building an EPR in Olkiluoto (Finland). Mid 2004, the French electricity utility EDF selected an EPR to be built in France. In 2005, Framatome ANP, an AREVA and Siemens company, announced that they will be pursuing a design certification in the U.S. The EPR development is based on the latest PWR product lines of former Framatome (N4) and Siemens Nuklear (Konvoi). As an introductory part, different aspects of the EPR core characteristics connected to fuel assembly design are presented. It includes means of ensuring reactivity control like hybrid AIC/B4C control rod absorbers and gadolinium as burnable absorber integrated in fuel rods, and specific options for in-core instrumentation, such as Aeroball type instrumentation. Then the design requirements for the EPR fuel assembly are presented in term of very high burnup capacity, rod cladding and fuel assembly reliability. Framatome ANP fuel assembly product characteristics meeting these requirements are then described. EPR fuel assembly design characteristics benefit from the experience feedback of the latest fuel assembly products designed within Framatome ANP, leading to resistance to assembly deformation, high fuel rod restraint and prevention of handling hazards. EPR fuel assembly design features the best components composing the cornerstones of the upgraded family of fuel assemblies that FRAMATOME ANP proposes today. This family is based on a set of common characteristics and associated features, which include the HMP grid as bottom end spacer, the MONOBLOC guide tube and the Robust FUELGUARD as lower tie plate, the use of the M5 Alloy, as cladding and structure material. This fully re-crystallized, ternary Zr-Nb-O alloy produces radically improved in-reactor corrosion, very low hydrogen uptake and growth and an excellent creep behavior, which are described there. EPR fuel assembly description also includes fuel rod

On the annealing of the EPR dislocation signal in silicon

International Nuclear Information System (INIS)

Zolotukhin, M.N.; Kveder, V.V.; Osip'yan, Yu.A.

1981-01-01

The annealing kinetics of the (EPR) dislocation signal (D-centers) in silicon is studied. The disappearance of the dislocation EPR signal as a result of annealing is ascribed to rearrangement of the nuclei of the partial dislocations accompanied by pairwise ''closing'' of the broken bonds in the S=0 state. The height of the energy barrier for the rearrangement process is approximately 2 eV. A residual ''nonannealing'' EPR signal is observed in strongly deformed silicon crystals. It resembles an isotropic line with a width approximately 7.5 Oe and a g-factor approximately 2.006. It is suggested that the respective EPR centers (O-centers) are similar to the EPR centers in amorphic silicon [ru

Magnetic, catalytic, EPR and electrochemical studies on binuclear ...

Indian Academy of Sciences (India)

Magnetic, catalytic, EPR and electrochemical studies on binuclear copper(II) complexes ... to the oxidation of 3,5-di--butylcatechol to the corresponding quinone. ... EPR spectral studies in methanol solvent show welldefined four hyperfine ...

EPR spectroscopy of complex biological iron-sulfur systems.

Science.gov (United States)

Hagen, Wilfred R

2018-02-21

From the very first discovery of biological iron-sulfur clusters with EPR, the spectroscopy has been used to study not only purified proteins but also complex systems such as respiratory complexes, membrane particles and, later, whole cells. In recent times, the emphasis of iron-sulfur biochemistry has moved from characterization of individual proteins to the systems biology of iron-sulfur biosynthesis, regulation, degradation, and implications for human health. Although this move would suggest a blossoming of System-EPR as a specific, non-invasive monitor of Fe/S (dys)homeostasis in whole cells, a review of the literature reveals limited success possibly due to technical difficulties in adherence to EPR spectroscopic and biochemical standards. In an attempt to boost application of System-EPR the required boundary conditions and their practical applications are explicitly and comprehensively formulated.

EPR study of free radicals in non- and gamma-irradiated nutritive supplements containing anthocyanins concentrate from lyophilized red wine

Energy Technology Data Exchange (ETDEWEB)

Mladenova, Ralitsa B., E-mail: ralitsa@ic.bas.b [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Firzov, Cyril [Institute of Cryobiology and Food Technology, 1162 Sofia (Bulgaria); Yordanov, Nicola D. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

2010-09-15

Nutritive supplements Enoviton, Enoviton C and Enoviton CE containing standardized anthocyanins from lyophilized red wine, vitamins (some of them) and excipients were investigated by EPR spectrometry before and after gamma-irradiation. Non-irradiated samples exhibit one singlet line with g=2.0039{+-}0.0002, most probably due to free radicals from anthocyanins. After irradiation with 10 kGy gamma-rays, tablets of Enoviton, Enoviton S and Enoviton SE, all exhibit complex EPR signals centered at a g-value of g=2.0034. The EPR spectrum of irradiated Enoviton is different from that of Enoviton S or Enoviton SE due to the overlap of the spectra of microcrystalline cellulose and the background singlet spectrum present in all tablets with the EPR resonance due to irradiated ascorbic acid (in Enoviton S and Enoviton SE). Gamma-induced free radicals exhibit long time stability-for a six months period the intensity of central peak decrease with 30-40%.

EPR study of free radicals in non- and gamma-irradiated nutritive supplements containing anthocyanins concentrate from lyophilized red wine

Science.gov (United States)

Mladenova, Ralitsa B.; Firzov, Cyril; Yordanov, Nicola D.

2010-09-01

Nutritive supplements Enoviton, Enoviton C and Enoviton CE containing standardized anthocyanins from lyophilized red wine, vitamins (some of them) and excipients were investigated by EPR spectrometry before and after gamma-irradiation. Non-irradiated samples exhibit one singlet line with g=2.0039±0.0002, most probably due to free radicals from anthocyanins. After irradiation with 10 kGy gamma-rays, tablets of Еnoviton, Еnoviton С and Еnoviton СЕ, all exhibit complex EPR signals centered at a g-value of g=2.0034. The EPR spectrum of irradiated Enoviton is different from that of Еnoviton С or Еnoviton СЕ due to the overlap of the spectra of microcrystalline cellulose and the background singlet spectrum present in all tablets with the EPR resonance due to irradiated ascorbic acid (in Еnoviton С and Еnoviton СЕ). Gamma-induced free radicals exhibit long time stability—for a six months period the intensity of central peak decrease with 30-40%.

EPR study on gamma-irradiated fruits dehydrated via osmosis

Energy Technology Data Exchange (ETDEWEB)

Yordanov, N.D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)]. E-mail: ndyepr@bas.bg; Aleksieva, K. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

2007-06-15

The shape and time stability of the electron paramagnetic resonance (EPR) spectra of non- and {gamma}-irradiated papaya, melon, cherry and fig samples dehydrated via osmosis are reported. It is shown that non-irradiated samples are generally EPR silent whereas {gamma}-irradiated exhibit 'sugar-like' EPR spectra. The recorded EPR spectra are monitored for a period of 7 months after irradiation (stored at low humidity and in the dark). The results suggest longer period of unambiguous identification of the radiation processing of osmose dehydrated fruits. Therefore, the Protocol EN 13708,2001 issued by CEN is fully applicable for the studied fruit samples.

EPR trademark project delivery. The value of experience

International Nuclear Information System (INIS)

Leverenz, Ruediger

2013-01-01

We are building the EPR trademark reactor fleet. Together. With four EPR trademark projects under construction in the world, AREVA has unrivalled experience in the delivery of large-scale nuclear projects, including more than a thousand lessons learned captured from Olkiluoto 3 and Flamanville 3 projects. This book of knowledge as well as the return of experience of AREVA's and EDF's teams are now being fully leveraged on ongoing projects, especially on Flamanville 3 and Taishan, and will be incorporated in all future EPR TM projects.

Some ideas on the EPR

International Nuclear Information System (INIS)

2003-01-01

Facing the debate and controversial between partisans and opponents of the European Pressurized Reactor construction, the SFP energy Group aims to offer some reflexions. In this framework the following topics are discussed: the french nuclear park and its replacement, the energy costs, the nuclear reactors profitability, the generation IV reactors. The paper examines then the EPR technology and its cost to conclude on the advantage of an EPR construction, in the case of an energy policy based on the nuclear. This last point seems to be the real challenge of the problem. (A.L.B.)

PropeR: a multi disciplinary EPR system

NARCIS (Netherlands)

van der Linden, Helma; Boers, Gerrit; Tange, Huibert; Talmon, Jan; Hasman, Arie

2003-01-01

This article describes the architecture of an EPR system developed for the PropeR project. This EPR system not only aims at supporting home care of stroke patients, but is also designed in such a way that it can be ported to other medical services without much effort. We will briefly describe the

EDITORIAL Light-induced material organization Light-induced material organization

Science.gov (United States)

Vainos, Nikos; Rode, Andrei V.

2010-12-01

Light-induced material organization extends over a broad area of research, from photon momentum transfer to atoms, molecules and particles, serving the basis for optical trapping, and expands into the laser-induced changes of material properties through photopolymerization, photodarkening, and materials ablation. Relevant phenomena are observed over many orders of magnitude of light intensity, from a few kW cm-2 for the optical trapping of living cells to 1014 W cm-2 encountered in femtosecond laser micromachining and micro-explosion. Relevant interactions reveal a rich palette of novel phenomena in the solid state, from subtle excitations and material organization to phase transformations, non-equilibrium and transient states. The laser-induced material modifications relate to changes in the crystal structure and the molecular bonding, phase transitions in liquid state, ablation and plasma production associated with extreme pressure and temperature conditions towards entirely new states of matter. The underlying physical mechanisms form the foundations for micro-engineering photonic and other functional devices and lead the way to relevant applications. At the same time, they hold the potential for creating non-equilibrium material states and a range of fundamentally new products not available by other means. The fundamental understanding of both materials nature and functional behaviour will ultimately yield novel devices and improved performance in several fields. The far reaching goals of these studies relate to the development of new methods and technologies for micro- and nano-fabrication, not only offering a significant reduction of cost, but also expanding the fabrication capabilities into unexplored areas of biophotonics and nanotechnology. This special issue of Journal of Optics presents some very recent and exciting advances in the field of materials manipulation by laser beams, aiming to underline its current trends. In optical trapping research we

The Flamanville 3 EPR reactor; Le reacteur EPR Flamanville 3

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

On April 10. 2007, the french government authorized EDF to create on the site of Flamanville ( La Manche) a nuclear base installation containing a pressurized water EPR type reactor. This nuclear reactor, conceived by AREVA NP and EDF, is the first copy of a generation susceptible to replace later, at least partly, the French nuclear reactors at present in operation.Within the framework of its mission of technical support of the Authority of Nuclear Safety ( A.S.N.), the I.R.S.N. widely contributed successively: to define the general objectives of safety assigned to this new generation of pressurized water nuclear reactors; to analyze the options of safety proposed by EDF for the EPR project; To deepen, upstream to the authorization of creation, the evaluation of the step of safety and the measures of conception retained by EDF that have to allow to respect the objectives of safety which were notified to it. (N.C.)

Polymer therapeutics and the EPR effect.

Science.gov (United States)

Maeda, Hiroshi

History of the EPR (enhanced permeability and retention) effect is discussed, which goes back to the analyses of molecular pathology in bacterial infection and edema (extravasation) formation. The first mediator we found for extravasation was bradykinin. Later on, were found nitric oxide and superoxide, then formation of peroxynitrite, that activates procollagenase. In this inflammatory setting many other vascular mediators are involved that are also common to cancer vasculature. Obviously cancer vasculature is defective architechtally, and this makes macromolecular drugs more permeable through the vascular wall. The importance of this pathophysiological event of EPR effect can be applied to macromolecular drug-delivery, or tumor selective delivery, which takes hours to achieve in the primary as well as metastatic tumors, not to mention of the inflamed tissues. The retention of the EPR means that such drugs will be retained in tumor tissues more than days to weeks. This was demonstrated initially, and most dramatically, using SMANCS, a protein-polymer conjugated-drug dissolved in lipid contrast medium (Lipiodol) by administering intraarterially. For disseminating the EPR concept globally, or in the scientific community, Professor Ruth Duncan played a key role at the early stage, as she worked extensively on polymer- therapeutics, and knew its importance.

Water-resistant alanine-EPR dosimeter alanpol

International Nuclear Information System (INIS)

Peimel-Stuglik, Zofia; Bryl-Sandelewska, Teresa; Mirkowski, Krzysztof; Sartowska, Bozena

2009-01-01

Alanpol-water-resistant alanine-electron paramagnetic resonance (EPR) dosimeter consisted of cheap DL-α-alanine (9.8-27%) suspended in polyethylene matrix was presented. The rods (O=2.8 mm) were extruded from a hot mixture of alanine and low-density polyethylene. No grinding or crushing was used for alanine preparation. An orientation of cylindrical crystals, up to 300 μm long in parallel to the rod axis was responsible for some differences in a shape of EPR signal. These differences had no negative consequences for dosimetric applications. Signal-to-dose dependence was linear up to 10 kGy. Standard deviation of dosimetric answer was up to ±1.8% and up to 2.4% for dosimeters with 9.8% and 27% of DL-α-alanine, respectively. Irradiation temperature coefficient for both dosimeters was equal 0.2%/ deg. C. Hydrophobic properties of polyethylene and small number of alanine crystals located on the surface of the rod led to high resistance of dosimeters to water and humidity. The 24 h soaking of irradiated dosimeters in liquid water-reduced EPR signals by 3-4% and by 2-3% for dosimeters with 27% and 9.8% of DL-α-alanine, respectively. Three month storage time of irradiated dosimeters in room conditions decreases EPR signal for ∼3%.

Nano-emulsions of fluorinated trityl radicals as sensors for EPR oximetry

Science.gov (United States)

Charlier, N.; Driesschaert, B.; Wauthoz, N.; Beghein, N.; Préat, V.; Amighi, K.; Marchand-Brynaert, J.; Gallez, B.

2009-04-01

This article reports the development and evaluation of two nano-emulsions (F45T-03/HFB and F15T-03/PFOB) containing fluorinated trityl radicals dissolved in perfluorocarbons. Preparation with a high-pressure homogenizer conferred sub-micronic size to both nano-emulsions. In vitro and in vivo EPR spectroscopy showed that the nano-emulsions had much greater oxygen sensitivity than the hydrophilic trityl, CT-03. In vivo experiments in rodents confirmed the ability of the nano-emulsions to follow the changes in oxygen concentration after induced ischemia. Histological evaluation of the tissue injected with the nano-emulsions revealed some acute toxicity for the F45T-03/HFB nano-emulsion but none for the F15T-03/PFOB nano-emulsion. These new formulations should be considered for further EPR oximetry experiments in pathophysiological situations where subtle changes in tissue oxygenation are expected.

Time-resolved EPR study of singlet oxygen in the gas phase.

Science.gov (United States)

Ruzzi, Marco; Sartori, Elena; Moscatelli, Alberto; Khudyakov, Igor V; Turro, Nicholas J

2013-06-27

X-band EPR spectra of singlet O2((1)Δg) and triplet O2((3)Σg(-)) were observed in the gas phase under low molecular-oxygen pressures PO2 = 0.175-0.625 Torr, T = 293-323 K. O2((1)Δg) was produced by quenching of photogenerated triplet sensitizers naphthalene C8H10, perdeuterated naphthalene, and perfluoronaphthalene in the gas phase. The EPR spectrum of O2((1)Δg) was also observed under microwave discharge. Integrated intensities and line widths of individual components of the EPR spectrum of O2((3)Σg(-)) were used as internal standards for estimating the concentration of O2 species and PO2 in the EPR cavity. Time-resolved (TR) EPR experiments of C8H10 were the main focus of this Article. Pulsed irradiation of C8H10 in the presence of O2((3)Σg(-)) allowed us to determine the kinetics of formation and decay for each of the four components of the O2((1)Δg) EPR signal, which lasted for only a few seconds. We found that the kinetics of EPR-component decay fit nicely to a biexponential kinetics law. The TR EPR 2D spectrum of the third component of the O2((1)Δg) EPR spectrum was examined in experiments using C8H10. This spectrum vividly presents the time evolution of an EPR component. The largest EPR signal and the longest lifetime of O2((1)Δg), τ = 0.4 s, were observed at medium pressure PO2 = 0.4 Torr, T = 293 K. The mechanism of O2((1)Δg) decay in the presence of photosensitizers is discussed. EPR spectra of O2((1)Δg) evidence that the spin-rotational states of O2((1)Δg) are populated according to Boltzmann distribution in the studied time range of 10-100 ms. We believe that this is the first report dealing with the dependence of O2((1)Δg) EPR line width on PO2 and T.

In vivo EPR dosimetry of accidental exposures to radiation: experimental results indicating the feasibility of practical use in human subjects

International Nuclear Information System (INIS)

Miyake, Minoru; Liu, K.J.; Walczak, T.M.; Swartz, H.M.

2000-01-01

Low frequency electron paramagnetic resonance (EPR) provides the potential advantage of making accurate and sensitive measurements of absorbed radiation dose in teeth in situ, i.e. without removing the teeth from the potential victim. The potential limiting factors for making such measurements are: (1) whether low frequency EPR is sufficiently sensitive to detect radiation-induced signal in human teeth; (2) whether sufficient sensitivity can be maintained under in vivo conditions. In this manuscript, we summarize results indicating that this approach is feasible. Using 1.2 GHz EPR spectroscopy, we found that the lower limit for these measurements in isolated human teeth is 0.2 Gy or lower. Measurements of radiation-induced EPR signals in the teeth of living rats were achieved with sufficient sensitivity to indicate that, when taking into consideration the larger mass of human teeth, similar measurements in human teeth in situ would provide sensitivity in the dose range for potential accidental exposures. We estimate that the current lower limit for detecting radiation doses in human teeth in situ (in vivo) is 0.5-1.0 Gy; this would be sufficient for determining if a person has been exposed to potentially life threatening doses of ionizing radiation. The limiting factor for sensitivity appears to be background signals rather than signal/noise, and there are feasible means to overcome this problem and further increase sensitivity. The additional instrumental developments required to make an effective in vivo EPR dosimetric spectrometer for the measurements in teeth in human subjects in situ, seem quite achievable

UV Light Induces Dedoping of Polyaniline

Directory of Open Access Journals (Sweden)

Yuki Kaitsuka

2016-01-01

Full Text Available UV (Ultra-Violet light-driven change in optical absorption of polyaniline (PANI is reported. Irradiation of UV light to PANI/camphor sulfonic acid prepared by electrochemical polymerization allows dedoping of the PANI. Especially, UV light irradiation in the presence of a radical trap agent effectively reduces (dedoping the PANI. The result in this study is quite simple; however, this may be a first report for light-induced dedoping (color change of a conductive polymer.

Computational and instrumental methods in EPR

CERN Document Server

Bender, Christopher J

2006-01-01

Computational and Instrumental Methods in EPR Prof. Bender, Fordham University Prof. Lawrence J. Berliner, University of Denver Electron magnetic resonance has been greatly facilitated by the introduction of advances in instrumentation and better computational tools, such as the increasingly widespread use of the density matrix formalism. This volume is devoted to both instrumentation and computation aspects of EPR, while addressing applications such as spin relaxation time measurements, the measurement of hyperfine interaction parameters, and the recovery of Mn(II) spin Hamiltonian parameters via spectral simulation. Key features: Microwave Amplitude Modulation Technique to Measure Spin-Lattice (T1) and Spin-Spin (T2) Relaxation Times Improvement in the Measurement of Spin-Lattice Relaxation Time in Electron Paramagnetic Resonance Quantitative Measurement of Magnetic Hyperfine Parameters and the Physical Organic Chemistry of Supramolecular Systems New Methods of Simulation of Mn(II) EPR Spectra: Single Cryst...

Pressurized water reactors: the EPR project

International Nuclear Information System (INIS)

Py, J.P.; Yvon, M.

2007-01-01

EPR (originally 'European pressurized water reactor', and now 'evolutionary power reactor') is a model of reactor initially jointly developed by French and German engineers which fulfills the particular safety specifications of both countries but also the European utility requirements jointly elaborated by the main European power companies under the initiative of Electricite de France (EdF). Today, two EPR-based reactors are under development: one is under construction in Finland and the other, Flamanville 3 (France), received its creation permit decree on April 10, 2007. This article presents, first, the main objectives of the EPR, and then, describes the Flamanville 3 reactor: reactor type and general conditions, core and conditions of operation, primary and secondary circuits with their components, main auxiliary and recovery systems, man-machine interface and instrumentation and control system, confinement and serious accidents, arrangement of buildings. (J.S.)

E-PR technologies in political party activities

OpenAIRE

Tereshchuk Vitaliy Ivanovych

2016-01-01

The article discusses the role of the Internet as an important communicative tool in the field of political PR. The article reviews the characteristics of PR-activities on the Internet and the features of e-PR in the political sphere. Particular attention is paid to the system of political party’s e-PR tools.

EPR: the nuclear impasse; EPR: l'impasse nucleaire

Energy Technology Data Exchange (ETDEWEB)

Marillier, F. [Association Ecologiste Greenpeace (France)

2008-07-01

The questions relative to the climatic change constitute crucial challenges for the next ten years. In this context the author aims to show how the EPR project illustrates the nuclear french ''autism''. He presents and analyzes the international and environmental impacts of this obsolete technology, as a project useless and dangerous. (A.L.B.)

Effects of water treatment and sample granularity on radiation sensitivity and stability of EPR signals in X-ray irradiated bone samples

International Nuclear Information System (INIS)

Ciesielski, Bartlomiej; Krefft, Karolina; Penkowski, Michal; Kaminska, Joanna; Drogoszewska, Barbara

2014-01-01

The article describes effects of sample conditions during its irradiation and electron paramagnetic resonance (EPR) measurements on the background (BG) and dosimetric EPR signals in bone. Intensity of the BG signal increased up to two to three times after crushing of bone to sub-millimetre grains. Immersion of samples in water caused about 50 % drop in intensity of the BG component followed by its regrowth in 1-2 months. Irradiation of bone samples produced an axial dosimetric EPR signal (radiation-induced signal) attributed to hydroxyapatite component of bone. This signal was stable and was not affected by water. In samples irradiated in dry conditions, EPR signal similar to the native BG was also generated by radiation. In samples irradiated in wet conditions, this BG-like component was initially much smaller than in bone irradiated as dry, but increased in time, reaching similar levels as in dry-irradiated samples. It is concluded that accuracy of EPR dosimetry in bones can be improved, if calibration of the samples is done by their irradiations in wet conditions. (authors)

EPR spectra of some irradiated polycrystalline perrhenate

International Nuclear Information System (INIS)

Zaitseva, N.G.; Constantinescu, M.; Georgescu, R.; Constantinescu, O.

1978-10-01

An EPR study of the paramagnetic centers formed by γ, electron and neutron irradiation of the NaReO 4 and KReO 4 was made. In the EPR spectra of the powder samples irradiated γ, with electrons and neutrons, the presence of three types of paramagnetic centers was observed. From the EPR parameters, the centers were attributed to the ReOsub(4)sup(.), ReOsub(3)sup(.) and ReOsub(2)sup(.) radicals respectively. The lower intensity of the spectra observed by KReO 4 samples irradiation showed a higher radioresistance of the KReO 4 than that of NaReO 4 . A radiolitical scheme taking into account the paramagnetic centers formation was proposed. (author)

Active cancellation - A means to zero dead-time pulse EPR.

Science.gov (United States)

Franck, John M; Barnes, Ryan P; Keller, Timothy J; Kaufmann, Thomas; Han, Songi

2015-12-01

The necessary resonator employed in pulse electron paramagnetic resonance (EPR) rings after the excitation pulse and creates a finite detector dead-time that ultimately prevents the detection of signal from fast relaxing spin systems, hindering the application of pulse EPR to room temperature measurements of interesting chemical or biological systems. We employ a recently available high bandwidth arbitrary waveform generator (AWG) to produce a cancellation pulse that precisely destructively interferes with the resonant cavity ring-down. We find that we can faithfully detect EPR signal at all times immediately after, as well as during, the excitation pulse. This is a proof of concept study showcasing the capability of AWG pulses to precisely cancel out the resonator ring-down, and allow for the detection of EPR signal during the pulse itself, as well as the dead-time of the resonator. However, the applicability of this approach to conventional EPR experiments is not immediate, as it hinges on either (1) the availability of low-noise microwave sources and amplifiers to produce the necessary power for pulse EPR experiment or (2) the availability of very high conversion factor micro coil resonators that allow for pulse EPR experiments at modest microwave power. Copyright © 2015 Elsevier Inc. All rights reserved.

Light-induced vegetative anthocyanin pigmentation in Petunia

Science.gov (United States)

Albert, Nick W.; Lewis, David H.; Zhang, Huaibi; Irving, Louis J.; Jameson, Paula E.; Davies, Kevin M.

2009-01-01

The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins and flavonols, as well as the activation of the early and late flavonoid biosynthetic genes required for flavonol and anthocyanin production. Pigmentation in Lc petunia only occurred under conditions which normally induce a modest amount of anthocyanin to accumulate in wild-type Mitchell petunia [Petunia axillaris×(Petunia axillaris×Petunia hybrida cv. ‘Rose of Heaven’)]. Anthocyanin pigmentation in Lc petunia leaves appears to screen underlying photosynthetic tissues, increasing light saturation and light compensation points, without reducing the maximal photosynthetic assimilation rate (Amax). In the Lc petunia system, where the bHLH factor Leaf colour is constitutively expressed, expression of the bHLH (Lc) and WD40 (An11) components of the anthocyanin regulatory system were not limited, suggesting that the high-light-induced anthocyanin pigmentation is regulated by endogenous MYB transcription factors. PMID:19380423

On the correlations between the particles in the EPR-paradoxon

International Nuclear Information System (INIS)

Treder, H.J.

1984-01-01

The Einstein-Podolsky-Rosen 'gedanken-experiment' does not imply non-local interactions or an 'action-at-a-distance'. Contrary, the EPR proves the measurements at one particle does not have influences at canonical variables of the other particles if the quantum-mechanical commutation relations are true. But, the EPR implices correlations between the particles which come in by 'subjective knowledge'. These correlations are a priori informations about the relative motion or, complementarily, about the motion of the center of mass. The impression of an action-at-a-distance is produced by the use of usual particle coordinates in the EPR-arrangements. The discussion of the Einstein-Podolsky-Rosen 'gedanken-experiment' (EPR) has been going on over fifty years. Einstein, Podolsky, and Rosen formulated their famous paradox in 1935, and in the discussion between N. Bohr (1935, 1949) and Einstein (1936, 1948); A. Einstein (1948) made his point that the EPR implied an 'action-at-a-distance' for quantum-mechanical particles (without obvious classical interactions). His argument is the starting point for the recent discussion about EPR and causality (see A. Aspect 1981). (author)

EPR and X-ray diffraction investigation of some Greek marbles and limestones

International Nuclear Information System (INIS)

Duliu, Octavian; Grecu, Maria Nicoleta; Cristea, Corina

2009-01-01

Twelve different marble and limestone samples collected from well-known Greek quarries have been investigated by X-ray diffraction and electron paramagnetic resonance (EPR). X-ray diffraction spectra permitted to determine both major (calcite and dolomite) and minor (quartz or magnesite) mineralogical components. EPR has been used to investigate the same samples unirradiated and after 10 kGy gamma-ray irradiation. The unirradiated samples display typical EPR spectra of Mn 2+ in calcite and dolomite as well as a superposition of these while some samples displayed EPR free radicals signals of centers (low field signal) and centers (high field signal). From X-ray diffraction and EPR spectra it was possible to extract numerical values of several numerical parameters such as dolomite to calcite ratio, EPR intensity parameter, and low field to high field EPR signals intensity ratio. These values as well as the correlation coefficients between the digital functions that described the low field Mn 2+ ions EPR line have been used as entry data for cluster analysis to quantify the resemblance and differences between analyzed samples. (authors)

Implementing a new EPR lineshape parameter for organic radicals in carbonaceous matter.

Science.gov (United States)

Bourbin, Mathilde; Du, Yann Le; Binet, Laurent; Gourier, Didier

2013-07-17

Electron Paramagnetic Resonance (EPR) is a non-destructive, non-invasive technique useful for the characterization of organic moieties in primitive carbonaceous matter related to the origin of life. The classical EPR parameters are the peak-to-peak amplitude, the linewidth and the g factor; however, such parameters turn out not to suffice to fully determine a single EPR line. In this paper, we give the definition and practical implementation of a new EPR parameter based on the signal shape that we call the R10 factor. This parameter was originally defined in the case of a single symmetric EPR line and used as a new datation method for organic matter in the field of exobiology. Combined to classical EPR parameters, the proposed shape parameter provides a full description of an EPR spectrum and opens the way to novel applications like datation. Such a parameter is a powerful tool for future EPR studies, not only of carbonaceous matter, but also of any substance which spectrum exhibits a single symmetric line. The paper is a literate program-written using Noweb within the Org-mode as provided by the Emacs editor- and it also describes the full data analysis pipeline that computes the R10 on a real EPR spectrum.

Overview of LBB implementation for the EPR

International Nuclear Information System (INIS)

Cauquelin, C.

1997-01-01

This paper presents an overview of the use of leak-before-break (LBB) analysis for EPR reactors. EPR is an evolutionary Nuclear Island of the 4 loop x 1500 Mwe class currently in the design phase. Application of LBB to the main coolant lines and resulting design impacts are summarized. Background information on LBB analysis in France and Germany is also presented

Overview of LBB implementation for the EPR

Energy Technology Data Exchange (ETDEWEB)

Cauquelin, C.

1997-04-01

This paper presents an overview of the use of leak-before-break (LBB) analysis for EPR reactors. EPR is an evolutionary Nuclear Island of the 4 loop x 1500 Mwe class currently in the design phase. Application of LBB to the main coolant lines and resulting design impacts are summarized. Background information on LBB analysis in France and Germany is also presented.

Severe accident analysis to prevent high pressure scenarios in the EPR TM

International Nuclear Information System (INIS)

Azarian, G.; Gandrille, P.; Gasperini, M.; Klein, R.

2010-01-01

The EPR TM has incorporated several design features in order to specifically address major severe accident safety issues. In particular, it was designed with the objective to transfer high pressure core melt scenarios into a low pressure scenario with high reliability so that a high pressure vessel failure can be practically eliminated. It is the key issue in the defense-in-depth approach, for a postulated severe accident with core melting, to prevent any risk of containment failure due to possible Direct Containment Heating or due to reactor vessel rocketing which results from vessel failure at high pressure. Temperature-induced steam generator tube rupture, which could lead to a radiological containment bypass, has also to be prevented. On the basis of the analysis of the main high pressure core melt scenarios which are calculated with the MAAP4.07 code which was developed to support the EPR TM, this paper explores the benefits of primary depressurization by dedicated valves on transient evolutions. It specifically addresses the thermal response of the structures by sensitivity studies involving the timing of valve actuation. It outlines that a grace period of at least one hour is available for a delayed valve actuation without inducing excessive loads and without increasing the risk of a temperature-induced steam generator tube rupture. (authors)

EPR study of free radicals in bread

Science.gov (United States)

Yordanov, Nicola D.; Mladenova, Ralitsa

2004-05-01

The features of the recorded EPR spectra of paramagnetic species formed in bread and rusk are reported. The appearance of free radicals in them is only connected with their thermal treatment since the starting materials (flour and grains) exhibit very weak EPR signal. The obtained EPR spectra are complex and indicate that: (i) the relative number of paramagnetic species depends on the temperature and treating time of the raw product; (ii) the g-values are strongly temperature dependent with a tendency to coincide at t≥220 °C. Because of the relatively low (150-220 °C) temperature of thermal treatment, the studied free radicals can be assumed to appear in the course of the browning (Maillard) reaction and not to the carbonization of the material.

EPR of impurity ions in disordered solids

International Nuclear Information System (INIS)

Kliava, J.

1986-01-01

The state of the art in the EPR spectroscopy of disordered solids is reviewed and theoretical aspects of the EPR shape in disordered systems are discussed. Emphasis is placed on the concept of the joint probability density of the spin Hamiltonian parameters. A survey of experimental data is provided on distributions of spin Hamiltonian parametes obtained using computer simulation techniques. A quantitative information is given on the short-range ordering in disordered materials available from EPR studies. A procedure of extracting such type of data which consists in a transformation from the distribution of the spin Hamiltonian parameters to that of atomic coordinates in the surrounding of a paramagnetic center is outlined. Numerical estimates of the degree of continuous disorder are reviewed

Multifrequency EPR study on freeze-dried fruits before and after X-ray irradiation

Science.gov (United States)

Yordanov, N. D.; Aleksieva, K.; Dimitrova, A.; Georgieva, L.; Tzvetkova, E.

2006-09-01

X-, K- and Q-band EPR studies on lyophilized whole pulp parts of blue plum, apricot, peach, melon as well as achens and pulp separately of strawberry before and after X-ray irradiation are reported. Before irradiation all samples show in X band a weak singlet EPR line with g=2.0030±0.0005, except melon, which is EPR silent. Immediately after irradiation all samples exhibit complex fruit-depending spectra, which decay with time and change to give, in ca. 50 days, an asymmetric singlet EPR line with g=2.0041±0.0005. Only apricot pulp gave a typical "sugar-like" EPR spectrum. Singlet EPR lines recorded after irradiation in X -band are K- and Q-band resolved as typical anisotropic EPR spectra with g=2.0023±0.0003 and g⊥=2.0041±0.0005. In addition, K- and Q-band EPR spectra of all samples show a superposition with the six EPR lines of Mn 2+ naturally present in the fruits. The saturation behavior of the EPR spectra of achens of lyophilized and fresh strawberry is also studied. The differences in g factors of samples before and after X-ray irradiation might be used for the identification of radiation processing of fruits in the case of pulp and the differences in the EPR saturation behavior might be used for the achens of strawberry.

Holographic EPR Pairs, Wormholes and Radiation

OpenAIRE

Chernicoff, Mariano; Güijosa, Alberto; Pedraza, Juan F.

2013-01-01

As evidence for the ER=EPR conjecture, it has recently been observed that the string that is holographically dual to an entangled quark-antiquark pair separating with (asymptotically) uniform acceleration has a wormhole on its worldsheet. We point out that a two-sided horizon and a wormhole actually appear for much more generic quark-antiquark trajectories, which is consistent with the fact that the members of an EPR pair need not be permanently out of causal contact. The feature that determi...

EPR of alanine irradiated by neutrons

International Nuclear Information System (INIS)

Pivovarov, S.P.; Seredavina, T.A.; Zhdanov, S.V.; Mul'gin, S.I.; Zhakparov, R.K.

2001-01-01

In the work the first results of EPR studies of alanine, irradiated with diverse doses at neutron cyclotron generator different conditions and on the critical reactor stand are presented. A dose linearity dependence of EPR signal is observing, the methods of γ-background contribution separation are discussed. Obtain results is giving the basis to recommendation of alanine as an effective detector irradiation. However it is demanded the farther study on clarification of radiation sensitivity value dependence on the neutron energy spectrum form

Retrospective individual dosimetry using luminescence and EPR after radiation accidents

International Nuclear Information System (INIS)

Goeksu, H.Y.; Wieser, A.; Ulanovsky, A.

2007-01-01

requires further investigation. Applicability of suggested procedure need to be tested under factory conditions using the latest material and card technology. Feasibility of production of such cards on an industrial scale is discussed. Alternatively individual dose after emergency situations can be reconstructed by assessment of absorbed dose in human tooth enamel by electron paramagnetic resonance (EPR) measurements. From absorbed dose in tooth enamel the effective dose and dose in organs can be reconstructed in consideration of photon energy response characteristic of teeth, and photon energy spectrum and geometry of the exposure field. In this project the applicability of EPR measurements with teeth was extended by reducing the detection threshold and computation of the photon energy response characteristic of deciduous teeth. It is shown that current limitation of EPR measurement with teeth at low absorbed dose is caused by incomplete consideration of the EPR spectrum of nonradiation induced (initial) radicals. By adding further components for simulation of the initial EPR spectrum in the dose evaluation procedure, the critical value for detection of absorbed dose in tooth enamel could be decreased to 19 mGy. Dose conversion coefficients for deciduous teeth in dependence of photon energy and exposure geometry were computed by Monte Carlo simulation using a mathematical child phantom. For use with luminescence measurements with chip cards and EPR measurements with teeth a software was established that allows conversion of the measured dose to integral free-in-air kerma, tissue dose or dose water in dependence on exposure scenario. (orig.)

Acclimation of shade-tolerant and light-resistant Tradescantia species to growth light: chlorophyll a fluorescence, electron transport, and xanthophyll content.

Science.gov (United States)

Mishanin, Vladimir I; Trubitsin, Boris V; Patsaeva, Svetlana V; Ptushenko, Vasily V; Solovchenko, Alexei E; Tikhonov, Alexander N

2017-09-01

In this study, we have compared the photosynthetic characteristics of two contrasting species of Tradescantia plants, T. fluminensis (shade-tolerant species), and T. sillamontana (light-resistant species), grown under the low light (LL, 50-125 µmol photons m -2  s -1 ) or high light (HL, 875-1000 µmol photons m -2  s -1 ) conditions during their entire growth period. For monitoring the functional state of photosynthetic apparatus (PSA), we measured chlorophyll (Chl) a emission fluorescence spectra and kinetics of light-induced changes in the heights of fluorescence peaks at 685 and 740 nm (F 685 and F 740 ). We also compared the light-induced oxidation of P 700 and assayed the composition of carotenoids in Tradescantia leaves grown under the LL and HL conditions. The analyses of slow induction of Chl a fluorescence (SIF) uncovered different traits in the LL- and HL-grown plants of ecologically contrasting Tradescantia species, which may have potential ecophysiological significance with respect to their tolerance to HL stress. The fluorometry and EPR studies of induction events in chloroplasts in situ demonstrated that acclimation of both Tradescantia species to HL conditions promoted faster responses of their PSA as compared to LL-grown plants. Acclimation of both species to HL also caused marked changes in the leaf anatomy and carotenoid composition (an increase in Violaxanthin + Antheraxantin + Zeaxanthin and Lutein pools), suggesting enhanced photoprotective capacity of the carotenoids in the plants grown in nature under high irradiance. Collectively, the results of the present work suggest that the mechanisms of long-term PSA photoprotection in Tradescantia are based predominantly on the light-induced remodeling of pigment-protein complexes in chloroplasts.

ISS protocol for EPR tooth dosimetry

International Nuclear Information System (INIS)

Onori, S.; Aragno, D.; Fattibene, P.; Petetti, E.; Pressello, M.C.

2000-01-01

The accuracy in Electron Paramagnetic Resonance (EPR) dose reconstruction with tooth enamel is affected by sample preparation, dosimetric signal amplitude evaluation and unknown dose estimate. Worldwide efforts in the field of EPR dose reconstruction with tooth enamel are focused on the optimization of the three mentioned steps in dose assessment. In the present work, the protocol implemented at ISS in the framework of the European Community Nuclear Fission Safety project 'Dose Reconstruction' is presented. A combined mechanical-chemical procedure for ground enamel sample preparation is used. The signal intensity evaluation is carried out with powder spectra simulation program. Finally, the unknown dose is evaluated individually for each sample with the additive dose method. The unknown dose is obtained by subtracting a mean native dose from the back-extrapolated dose. As an example of the capability of the ISS protocol in unknown dose evaluation, the results obtained in the framework of the 2nd International Intercomparison on EPR tooth enamel dosimetry are reported

Reconstructing Bohr's Reply to EPR in Algebraic Quantum Theory

Science.gov (United States)

Ozawa, Masanao; Kitajima, Yuichiro

2012-04-01

Halvorson and Clifton have given a mathematical reconstruction of Bohr's reply to Einstein, Podolsky and Rosen (EPR), and argued that this reply is dictated by the two requirements of classicality and objectivity for the description of experimental data, by proving consistency between their objectivity requirement and a contextualized version of the EPR reality criterion which had been introduced by Howard in his earlier analysis of Bohr's reply. In the present paper, we generalize the above consistency theorem, with a rather elementary proof, to a general formulation of EPR states applicable to both non-relativistic quantum mechanics and algebraic quantum field theory; and we clarify the elements of reality in EPR states in terms of Bohr's requirements of classicality and objectivity, in a general formulation of algebraic quantum theory.

Superhigh-frequency circuit for the EPR spectrometer with rectifier screening

International Nuclear Information System (INIS)

Zhizhchenko, G.A.; Tsvirko, L.V.

1983-01-01

The hamodyne SHF circuit of a 3-cm EPR spectrometer with a reflecting resonator is described. The optimum operating mode of SHF-rectifier at a constant phase difference is automatically assured in the circuit. The circuit employs a reflecting p-i-n- attenuator and a SHF-rectifier sereen which simplify the spectrometer tuming. The circuit is used in a miniature EPR radiospectrometer Minsk EPR-6-type

Multifrequency EPR study on freeze-dried fruits before and after X-ray irradiation

Energy Technology Data Exchange (ETDEWEB)

Yordanov, N.D. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)]. E-mail: ndyepr@bas.bg; Aleksieva, K. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Dimitrova, A. [Laboratory EPR, Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Georgieva, L. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria); Tzvetkova, E. [Institute of Cryobiology and Food Technologies, 1162 Sofia (Bulgaria)

2006-09-15

X-, K- and Q-band EPR studies on lyophilized whole pulp parts of blue plum, apricot, peach, melon as well as achens and pulp separately of strawberry before and after X-ray irradiation are reported. Before irradiation all samples show in X band a weak singlet EPR line with g=2.0030+/-0.0005, except melon, which is EPR silent. Immediately after irradiation all samples exhibit complex fruit-depending spectra, which decay with time and change to give, in ca. 50days, an asymmetric singlet EPR line with g=2.0041+/-0.0005. Only apricot pulp gave a typical ''sugar-like'' EPR spectrum. Singlet EPR lines recorded after irradiation in X -band are K- and Q-band resolved as typical anisotropic EPR spectra with g{sub ||}=2.0023+/-0.0003 and g{sub -}bar =2.0041+/-0.0005. In addition, K- and Q-band EPR spectra of all samples show a superposition with the six EPR lines of Mn{sup 2+} naturally present in the fruits. The saturation behavior of the EPR spectra of achens of lyophilized and fresh strawberry is also studied. The differences in g factors of samples before and after X-ray irradiation might be used for the identification of radiation processing of fruits in the case of pulp and the differences in the EPR saturation behavior might be used for the achens of strawberry.

Interpretation of the parameters of the EPR spectra of transition metal complexes

International Nuclear Information System (INIS)

Murav'ev, V.I.

2005-01-01

The calculated parameters of the EPR spectra of complexes of d 1 and d 9 ions, inclusive of MoOX 5 (X = Cl, Br), are reviewed. The covalent bond parameters used in the calculations were determined from EPR and experimental optical data (inverse problem of EPR spectroscopy). Various contributions to the expressions for the EPR parameters were compared. The observed abnormal values of the EPR parameters were discussed. The effects of charge-transfer states and the vibronic coupling on the components of g, A, and A L tensors were considered. Mechanisms of spin density transfer to ligands in paramagnetic complexes were proposed [ru

Spin entanglement, decoherence and Bohm's EPR paradox.

Science.gov (United States)

Cavalcanti, E G; Drummond, P D; Bachor, H A; Reid, M D

2009-10-12

We obtain criteria for entanglement and the EPR paradox for spin-entangled particles and analyse the effects of decoherence caused by absorption and state purity errors. For a two qubit photonic state, entanglement can occur for all transmission efficiencies. In this case, the state preparation purity must be above a threshold value. However, Bohm's spin EPR paradox can be achieved only above a critical level of loss. We calculate a required efficiency of 58%, which appears achievable with current quantum optical technologies. For a macroscopic number of particles prepared in a correlated state, spin entanglement and the EPR paradox can be demonstrated using our criteria for efficiencies eta > 1/3 and eta > 2/3 respectively. This indicates a surprising insensitivity to loss decoherence, in a macroscopic system of ultra-cold atoms or photons.

Full cycle rapid scan EPR deconvolution algorithm.

Science.gov (United States)

Tseytlin, Mark

2017-08-01

Rapid scan electron paramagnetic resonance (RS EPR) is a continuous-wave (CW) method that combines narrowband excitation and broadband detection. Sinusoidal magnetic field scans that span the entire EPR spectrum cause electron spin excitations twice during the scan period. Periodic transient RS signals are digitized and time-averaged. Deconvolution of absorption spectrum from the measured full-cycle signal is an ill-posed problem that does not have a stable solution because the magnetic field passes the same EPR line twice per sinusoidal scan during up- and down-field passages. As a result, RS signals consist of two contributions that need to be separated and postprocessed individually. Deconvolution of either of the contributions is a well-posed problem that has a stable solution. The current version of the RS EPR algorithm solves the separation problem by cutting the full-scan signal into two half-period pieces. This imposes a constraint on the experiment; the EPR signal must completely decay by the end of each half-scan in order to not be truncated. The constraint limits the maximum scan frequency and, therefore, the RS signal-to-noise gain. Faster scans permit the use of higher excitation powers without saturating the spin system, translating into a higher EPR sensitivity. A stable, full-scan algorithm is described in this paper that does not require truncation of the periodic response. This algorithm utilizes the additive property of linear systems: the response to a sum of two inputs is equal the sum of responses to each of the inputs separately. Based on this property, the mathematical model for CW RS EPR can be replaced by that of a sum of two independent full-cycle pulsed field-modulated experiments. In each of these experiments, the excitation power equals to zero during either up- or down-field scan. The full-cycle algorithm permits approaching the upper theoretical scan frequency limit; the transient spin system response must decay within the scan

EPR becomes reality at Finland's Olkiluoto 3

International Nuclear Information System (INIS)

Gueldner, R.; Giese, U.

2005-01-01

The EPR is a third-generation pressurized water reactor (PWR). Its development was started in 1992 by Framatome and Siemens within a Franco-German partnership. Since 2001 this work has been continued by Framatome ANP, which was formed when the two companies merged their nuclear businesses. The French company AREVA, world market leader in nuclear technology, holds a 66% share in Framatome ANP, with Siemens owning 34%. From the very start, development of the EPR was focused on improving plant safety and economics even further. The new reactor development was jointly financed together with the leading power utilities of both countries. The first steps towards realization of an EPR nuclear power plant were taken at Olkiluoto, Finland in 2004, consisting of initial preparation of the construction site. By mid-February 2005 the local municipality - Eurajoki - had issued a construction permit, and the Finnish Government a construction license pursuant to the Finnish Nuclear Energy Act. This had been preceded by a preliminary safety assessment prepared by the Finnish Radiation and Nuclear Safety Authority (STUK) for the Finnish Ministry of Trade and Industry in which STUK verified that it did not see any safety-related issues opposing issuance of the nuclear construction license. STUK emphasized that the evolutionary design of the EPR had been further improved by AREVA compared to the previous product lines. Concreting work began this spring and the unit will start commercial operation in 2009. Construction of an EPR has also been given the political go-ahead in France. According to the utility Electricite de France (EDF) the new reactor will be built as a forerunner of a later series at the site of Flamanville in Normandy. Construction is scheduled to begin in 2007. An EPR nuclear power plant has a rated electric capacity of around 1600 MW, depending on specific site conditions. Being the product of intense bilateral cooperation the EPR combines the technological

EPR and NMR spectroscopy on spin-labeled proteins

NARCIS (Netherlands)

Finiguerra, Michelina Giuseppina

2011-01-01

Spin labeling and electron paramagnetic resonance (EPR) have been employed to study structure and dynamics of proteins. The surface polarity of four single cysteine mutants of the Zn-azurin in frozen solution were studied using 275 GHz EPR (J-band), with the advantage compared to 9 GHz (X-band) and

A Comparative Evaluation of EPR and OxyLite Oximetry Using a Random Sampling of pO2 in a Murine Tumor

Science.gov (United States)

Vikram, Deepti S.; Bratasz, Anna; Ahmad, Rizwan; Kuppusamy, Periannan

2015-01-01

Methods currently available for the measurement of oxygen concentrations (oximetry) in viable tissues differ widely from each other in their methodological basis and applicability. The goal of this study was to compare two novel methods, particulate-based electron paramagnetic resonance (EPR) and OxyLite oximetry, in an experimental tumor model. EPR oximetry uses implantable paramagnetic particulates, whereas OxyLite uses fluorescent probes affixed on a fiber-optic cable. C3H mice were transplanted with radiation-induced fibrosarcoma (RIF-1) tumors in their hind limbs. Lithium phthalocyanine (LiPc) microcrystals were used as EPR probes. The pO2 measurements were taken from random locations at a depth of ~3 mm within the tumor either immediately or 48 h after implantation of LiPc. Both methods revealed significant hypoxia in the tumor. However, there were striking differences between the EPR and OxyLite readings. The differences were attributed to the volume of tissue under examination and the effect of needle invasion at the site of measurement. This study recognizes the unique benefits of EPR oximetry in terms of robustness, repeatability and minimal invasiveness. PMID:17705635

Spectra processing at tooth enamel dosimetry: Analytical description of EPR spectrum at different microwave power

International Nuclear Information System (INIS)

Tieliewuhan, E.; Ivannikov, A.; Zhumadilov, K.; Nalapko, M.; Tikunov, D.; Skvortsov, V.; Stepanenko, V.; Toyoda, S.; Tanaka, K.; Endo, S.; Hoshi, M.

2006-01-01

Variation of the electron paramagnetic resonance (EPR) spectrum of the human tooth enamel recorded at different microwave power is investigated. The analytical models describing the native and the radiation-induced signals in the enamel are proposed, which fit the experimental spectra in wide range of microwave power. These models are designed to use for processing the spectra of irradiated enamel at determination of the absorbed dose from the intensity of the radiation-induced signal

EPR and UV spectrometry investigation of sucrose irradiated with carbon particles

International Nuclear Information System (INIS)

Karakirova, Yordanka; Yordanov, Nicola D.

2010-01-01

Solid state/EPR (SS/EPR) dosimeters of carbon ions irradiated sucrose are studied with EPR, and their water solutions - with UV spectroscopy. Doses between 20 and 200 Gy are used with linear energy transfer (LET) values for carbon ions of 63, 77, 96 and 230 keV μm -1 . After irradiation all samples show typical for irradiated sucrose EPR and UV spectra. The obtained data are compared with those previously reported for nitrogen particles and gamma rays irradiated sucrose. The identical shape of both the EPR and UV spectra of irradiated with various type radiation samples suggests that generated free radicals are not influenced by the nature of radiation. The lack of difference in the line width of the separate lines or the whole EPR spectrum, obtained for gamma and heavy particles irradiation, suggests negligible spin-spin interaction among the radiation-generated free radicals in the samples. The linear dependence of the EPR response on the absorbed dose radiation is found to be higher when generated by gamma rays, than by the same absorbed dose of heavy particles. In addition, the EPR response for carbon ions is higher than that for nitrogen ions. Water solutions of irradiated sucrose exhibit UV spectrum with absorption maximum at 267 nm, attributed to the recombination products of free radicals. The UV band intensity depends on the absorbed dose radiation. The UV spectra obtained for carbon, nitrogen and gamma rays irradiated sucrose are also compared.

SU-C-BRD-05: Non-Invasive in Vivo Biodosimetry in Radiotherapy Patients Using Electron Paramagnetic Resonance (EPR) Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Bahar, N; Roberts, K; Stabile, F; Mongillo, N; Decker, RD; Wilson, LD; Husain, Z; Contessa, J; Carlson, DJ [Yale University School of Medicine, New Haven, Connecticut (United States); Williams, BB; Flood, AB; Swartz, HM [Geisel Medical School at Dartmouth University, Hanover, New Hampshire (United States)

2015-06-15

Purpose: Medical intervention following a major, unplanned radiation event can elevate the human whole body exposure LD50 from 3 to 7 Gy. On a large scale, intervention cannot be achieved effectively without accurate and efficient triage. Current methods of retrospective biodosimetry are restricted in capability and applicability; published human data is limited. We aim to further develop, validate, and optimize an automated field-deployable in vivo electron paramagnetic resonance (EPR) instrument that can fill this need. Methods: Ionizing radiation creates highly-stable, carbonate-based free radicals within tooth enamel. Using a process similar to nuclear magnetic resonance, EPR directly measures the presence of radiation-induced free radicals. We performed baseline EPR measurements on one of the upper central incisors of total body irradiation (TBI) and head and neck (H&N) radiotherapy patients before their first treatment. Additional measurements were performed between subsequent fractions to examine the EPR response with increasing radiation dose. Independent dosimetry measurements were performed with optically-stimulated luminescent dosimeters (OSLDs) and diodes to more accurately establish the relationship between EPR signal and delivered radiation dose. Results: 36 EPR measurements were performed over the course of four months on two TBI and four H & N radiotherapy patients. We observe a linear increase in EPR signal with increasing dose across the entirety of the tested range. A linear least squares-weighted fit of delivered dose versus measured signal amplitude yields an adjusted R-square of 0.966. The standard error of inverse prediction (SEIP) is 1.77 Gy. For doses up to 7 Gy, the range most relevant to triage, we calculate an SEIP of 1.29 Gy. Conclusion: EPR spectroscopy provides a promising method of retrospective, non-invasive, in vivo biodosimetry. Our preliminary data show an excellent correlation between predicted signal amplitude and delivered

The measurement of oxygen in vivo using EPR techniques

International Nuclear Information System (INIS)

Swartz, Harold M.; Clarkson, Robert B.

1998-01-01

The measurement of pO 2 in vivo using EPR has some features which have already led to very useful applications and this approach is likely to have increasingly wide and effective use. It is based on the effect of oxygen on EPR spectra which provides a sensitive and accurate means to measure pO 2 quantitatively. The development of oxygen-sensitive paramagnetic materials which are very stable, combined with instrumental developments, has been crucial to the in vivo applications of this technique. The physical basis and biological applications of in vivo EPR oximetry are reviewed, with particular emphasis on the use of EPR spectroscopy at 1 GHz using particulate paramagnetic materials for the repetitive and non-invasive measurement of pO 2 in tissues. In vivo EPR has already produced some very useful results which have contributed significantly to solving important biological problems. The characteristics of EPR oximetry which appear to be especially useful are often complementary to existing techniques for measuring oxygen in tissues. These characteristics include the capability of making repeated measurements from the same site, high sensitivity to low levels of oxygen, and non-invasive options. The existing techniques are especially useful for studies in small animals, where the depth of measurements is not an overriding issue. In larger animals and potentially in human subjects, non-invasive techniques seem to be immediately applicable to study phenomena very near the surface (within 10 mm) while invasive techniques have some very promising uses. The clinical uses of EPR oximetry which seem especially promising and likely to be undertaken in the near future are long-term monitoring of the status and response to treatment of peripheral vascular disease and optimizing cancer therapy by enabling it to be modified on the basis of the pO 2 measured in the tumour. (author)

Toward 2D and 3D imaging of magnetic nanoparticles using EPR measurements.

Science.gov (United States)

Coene, A; Crevecoeur, G; Leliaert, J; Dupré, L

2015-09-01

Magnetic nanoparticles (MNPs) are an important asset in many biomedical applications. An effective working of these applications requires an accurate knowledge of the spatial MNP distribution. A promising, noninvasive, and sensitive technique to visualize MNP distributions in vivo is electron paramagnetic resonance (EPR). Currently only 1D MNP distributions can be reconstructed. In this paper, the authors propose extending 1D EPR toward 2D and 3D using computer simulations to allow accurate imaging of MNP distributions. To find the MNP distribution belonging to EPR measurements, an inverse problem needs to be solved. The solution of this inverse problem highly depends on the stability of the inverse problem. The authors adapt 1D EPR imaging to realize the imaging of multidimensional MNP distributions. Furthermore, the authors introduce partial volume excitation in which only parts of the volume are imaged to increase stability of the inverse solution and to speed up the measurements. The authors simulate EPR measurements of different 2D and 3D MNP distributions and solve the inverse problem. The stability is evaluated by calculating the condition measure and by comparing the actual MNP distribution to the reconstructed MNP distribution. Based on these simulations, the authors define requirements for the EPR system to cope with the added dimensions. Moreover, the authors investigate how EPR measurements should be conducted to improve the stability of the associated inverse problem and to increase reconstruction quality. The approach used in 1D EPR can only be employed for the reconstruction of small volumes in 2D and 3D EPRs due to numerical instability of the inverse solution. The authors performed EPR measurements of increasing cylindrical volumes and evaluated the condition measure. This showed that a reduction of the inherent symmetry in the EPR methodology is necessary. By reducing the symmetry of the EPR setup, quantitative images of larger volumes can be

Toward 2D and 3D imaging of magnetic nanoparticles using EPR measurements

International Nuclear Information System (INIS)

Coene, A.; Crevecoeur, G.; Dupré, L.; Leliaert, J.

2015-01-01

Purpose: Magnetic nanoparticles (MNPs) are an important asset in many biomedical applications. An effective working of these applications requires an accurate knowledge of the spatial MNP distribution. A promising, noninvasive, and sensitive technique to visualize MNP distributions in vivo is electron paramagnetic resonance (EPR). Currently only 1D MNP distributions can be reconstructed. In this paper, the authors propose extending 1D EPR toward 2D and 3D using computer simulations to allow accurate imaging of MNP distributions. Methods: To find the MNP distribution belonging to EPR measurements, an inverse problem needs to be solved. The solution of this inverse problem highly depends on the stability of the inverse problem. The authors adapt 1D EPR imaging to realize the imaging of multidimensional MNP distributions. Furthermore, the authors introduce partial volume excitation in which only parts of the volume are imaged to increase stability of the inverse solution and to speed up the measurements. The authors simulate EPR measurements of different 2D and 3D MNP distributions and solve the inverse problem. The stability is evaluated by calculating the condition measure and by comparing the actual MNP distribution to the reconstructed MNP distribution. Based on these simulations, the authors define requirements for the EPR system to cope with the added dimensions. Moreover, the authors investigate how EPR measurements should be conducted to improve the stability of the associated inverse problem and to increase reconstruction quality. Results: The approach used in 1D EPR can only be employed for the reconstruction of small volumes in 2D and 3D EPRs due to numerical instability of the inverse solution. The authors performed EPR measurements of increasing cylindrical volumes and evaluated the condition measure. This showed that a reduction of the inherent symmetry in the EPR methodology is necessary. By reducing the symmetry of the EPR setup, quantitative images of

EPR-based distance measurements at ambient temperature

Science.gov (United States)

Krumkacheva, Olesya; Bagryanskaya, Elena

2017-07-01

Pulsed dipolar (PD) EPR spectroscopy is a powerful technique allowing for distance measurements between spin labels in the range of 2.5-10.0 nm. It was proposed more than 30 years ago, and nowadays is widely used in biophysics and materials science. Until recently, PD EPR experiments were limited to cryogenic temperatures (T biomolecules, the influence of a linker between the spin probe and biomolecule, and future opportunities.

Spin dynamics of light-induced charge separation in composites of semiconducting polymers and PC60BM revealed using Q-band pulse EPR.

Science.gov (United States)

Lukina, E A; Suturina, E; Reijerse, E; Lubitz, W; Kulik, L V

2017-08-23

Light-induced processes in composites of semiconducting polymers and fullerene derivatives have been widely studied due to their usage as active layers of organic solar cells. However the process of charge separation under light illumination - the key process of an organic solar cell is not well understood yet. Here we report a Q-band pulse electron paramagnetic resonance study of composites of the fullerene derivative PC 60 BM ([6,6]-phenyl-C 61 -butyric acid methyl ester) with different p-type semiconducting polymers regioregular and regiorandom P3HT (poly(3-hexylthiophene-2,5-diyl), MEH-PPV (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]), PCDTBT (poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)]), PTB7 (poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl}))), resulting in a detailed description of the in-phase laser flash-induced electron spin echo (ESE) signal. We found that in organic donor-acceptor composites the laser flash simultaneously induces species of two types: a polymer˙ + /fullerene˙ - spin-correlated polaron pair (SCPP) with an initial singlet spin state and (nearly) free polymer˙ + and fullerene˙ - species with non-equilibrium spin polarization. Species of the first type (SCPP) are well-known for polymer/fullerene blends and are usually associated with a charge-separated state. Also, spin polarization of long-living free species (polarons in deep traps) is affected by the laser flash, which is the third contribution to the flash-induced ESE signal. A protocol for extracting the in-phase ESE signal of the SCPP based on the dependence of the microwave nutation frequency on the strength of the spin coupling within the polaron pair was developed. Nutation experiments revealed an unusual pattern of the SCPP in RR-P3HT/PC 60 BM composites, from which the strength of the exchange interaction between the polymer

Elucidating the design principles of photosynthetic electron-transfer proteins by site-directed spin labeling EPR spectroscopy.

Science.gov (United States)

Ishara Silva, K; Jagannathan, Bharat; Golbeck, John H; Lakshmi, K V

2016-05-01

Site-directed spin labeling electron paramagnetic resonance (SDSL EPR) spectroscopy is a powerful tool to determine solvent accessibility, side-chain dynamics, and inter-spin distances at specific sites in biological macromolecules. This information provides important insights into the structure and dynamics of both natural and designed proteins and protein complexes. Here, we discuss the application of SDSL EPR spectroscopy in probing the charge-transfer cofactors in photosynthetic reaction centers (RC) such as photosystem I (PSI) and the bacterial reaction center (bRC). Photosynthetic RCs are large multi-subunit proteins (molecular weight≥300 kDa) that perform light-driven charge transfer reactions in photosynthesis. These reactions are carried out by cofactors that are paramagnetic in one of their oxidation states. This renders the RCs unsuitable for conventional nuclear magnetic resonance spectroscopy investigations. However, the presence of native paramagnetic centers and the ability to covalently attach site-directed spin labels in RCs makes them ideally suited for the application of SDSL EPR spectroscopy. The paramagnetic centers serve as probes of conformational changes, dynamics of subunit assembly, and the relative motion of cofactors and peptide subunits. In this review, we describe novel applications of SDSL EPR spectroscopy for elucidating the effects of local structure and dynamics on the electron-transfer cofactors of photosynthetic RCs. Because SDSL EPR Spectroscopy is uniquely suited to provide dynamic information on protein motion, it is a particularly useful method in the engineering and analysis of designed electron transfer proteins and protein networks. This article is part of a Special Issue entitled Biodesign for Bioenergetics--the design and engineering of electronic transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson. Copyright © 2016. Published by Elsevier B.V.

Einstein and the Quantum: The Secret Life of EPR

Science.gov (United States)

Fine, Arthur

2006-05-01

Locality, separation and entanglement -- 1930s style. Starting with Solvay 1927, we'll explore the background to the 1935 paper by Einstein, Podolsky and Rosen: how it was composed, the actual argument and principles used, and how the paper was received by Schroedinger, and others. We'll also look at Bohr's response: the extent to which Bohr connects with what Einstein was after in EPR and the extent to which EPR marks a shift in Bohr's thinking about the quantum theory. Time permitting, we will contrast EPR with Bell's theorem.

The EPR - technology for the 3rd millennium

International Nuclear Information System (INIS)

Bernstrauch, O.; Dubois, F.

2001-01-01

This paper is a story of a successful Franco-German co-operation: the EPR project. It is a rundown of the history of the EPR, before a decision is made to launch the lead-unit construction. The EPR is expected to progressively replace the existing nuclear power plants when they will reach the end of their service life. It integrates the latest technological advances, especially in safety and operational aspects and comprises more than 30 years operating experience. Thus, the EPR combines the qualities of its predecessors, the French N4 and the German Konvoi. The safety of the EPR was maximized both to prevent hypothetical accidents - even severe ones - and to reduce their consequences (corium spreading area, pre-stressed double containment with local liner, four-train safety systems...). The n+2 strategy (in the event of a problem with one train and even if a second train is undergoing maintenance, the remaining two are sufficient to perform the function) allows to perform maintenance during operation which leads consequently to short outage periods, highest availabilities and economical operation. Moreover, most of the EPR components are the result of mastered evolution. The reactor vessel, as a key element for the reactor service life, is designed to be in service for 60 years, the core is large (241 fuel elements instead of 205 in the N4 or 193 in the Konvoi) and the steam generators have higher efficiency. Along the same line, the core and core barrel design have been modified to allow a reduced uranium enrichment and the increase to 65 Gigawatt-day per metric-ton of the fuel discharge burn-up. Finally, the instrumentation and control systems minimize human error by giving the operators a grace period of at least 30 minutes to make decisions. (authors)

EPR spectroscopy of spices

Directory of Open Access Journals (Sweden)

R. T. Тimakova

2016-01-01

Full Text Available From 01 January 2017 you enter the interstate standard GOST 33271-2015 “Dry Spices, herbs and vegetable seasonings. Manual exposure in order to combat pathogens and other microorganisms” which States that the absorbed dose of radiation to the spices should be from 3 to 30 kGy. The study found that before the introduction of permissive legislative framework in the consumer market of Russia there are irradiated food products (chili, ground chili, ground spicy chili, black pepper. For radiation monitoring of food safety, we used the method of electron paramagnetic resonance (EPR, which allows quickly and with a high degree of reliability to establish the fact of irradiation. It is established that all samples of spices irradiated with dose of 12 kGy (technology radappertization gave typical spectra of the signals established by the method of electron paramagnetic resonance in the domestic EPR spectrometer, the intensity, amplitude and peak width of the EPR signal of samples of spices with the increase of irradiation dose increases. It is proven that repeated exposure no effect accumulation. Integration with 2017 Russia in the global practi ce of using radiation technologies of processing of food products and food raw materials with the purpose of extending shelf life confirms the need for a data Bank on the radiation sensitivity of various food products to determine the optimal doses and the eff ect of radiation doses on the shelf life and quality of products.

Chromatic assimilation unaffected by perceived depth of inducing light.

Science.gov (United States)

Shevell, Steven K; Cao, Dingcai

2004-01-01

Chromatic assimilation is a shift toward the color of nearby light. Several studies conclude that a neural process contributes to assimilation but the neural locus remains in question. Some studies posit a peripheral process, such as retinal receptive-field organization, while others claim the neural mechanism follows depth perception, figure/ground segregation, or perceptual grouping. The experiments here tested whether assimilation depends on a neural process that follows stereoscopic depth perception. By introducing binocular disparity, the test field judged in color was made to appear in a different depth plane than the light that induced assimilation. The chromaticity and spatial frequency of the inducing light, and the chromaticity of the test light, were varied. Chromatic assimilation was found with all inducing-light sizes and chromaticities, but the magnitude of assimilation did not depend on the perceived relative depth planes of the test and inducing fields. We found no evidence to support the view that chromatic assimilation depends on a neural process that follows binocular combination of the two eyes' signals.

Self-testing through EPR-steering

International Nuclear Information System (INIS)

Šupić, Ivan; Hoban, Matty J

2016-01-01

The verification of quantum devices is an important aspect of quantum information, especially with the emergence of more advanced experimental implementations of quantum computation and secure communication. Within this, the theory of device-independent robust self-testing via Bell tests has reached a level of maturity now that many quantum states and measurements can be verified without direct access to the quantum systems: interaction with the devices is solely classical. However, the requirements for this robust level of verification are daunting and require high levels of experimental accuracy. In this paper we discuss the possibility of self-testing where we only have direct access to one part of the quantum device. This motivates the study of self-testing via EPR-steering, an intermediate form of entanglement verification between full state tomography and Bell tests. Quantum non-locality implies EPR-steering so results in the former can apply in the latter, but we ask what advantages may be gleaned from the latter over the former given that one can do partial state tomography? We show that in the case of self-testing a maximally entangled two-qubit state, or ebit, EPR-steering allows for simpler analysis and better error tolerance than in the case of full device-independence. On the other hand, this improvement is only a constant improvement and (up to constants) is the best one can hope for. Finally, we indicate that the main advantage in self-testing based on EPR-steering could be in the case of self-testing multi-partite quantum states and measurements. For example, it may be easier to establish a tensor product structure for a particular party’s Hilbert space even if we do not have access to their part of the global quantum system. (paper)

HF-EPR, Raman, UV/VIS light spectroscopic, and DFT studies of the ribonucleotide reductase R2 tyrosyl radical from Epstein-Barr virus.

Directory of Open Access Journals (Sweden)

Ane B Tomter

Full Text Available Epstein-Barr virus (EBV belongs to the gamma subfamily of herpes viruses, among the most common pathogenic viruses in humans worldwide. The viral ribonucleotide reductase small subunit (RNR R2 is involved in the biosynthesis of nucleotides, the DNA precursors necessary for viral replication, and is an important drug target for EBV. RNR R2 generates a stable tyrosyl radical required for enzymatic turnover. Here, the electronic and magnetic properties of the tyrosyl radical in EBV R2 have been determined by X-band and high-field/high-frequency electron paramagnetic resonance (EPR spectroscopy recorded at cryogenic temperatures. The radical exhibits an unusually low g₁-tensor component at 2.0080, indicative of a positive charge in the vicinity of the radical. Consistent with these EPR results a relatively high C-O stretching frequency associated with the phenoxyl radical (at 1508 cm⁻¹ is observed with resonance Raman spectroscopy. In contrast to mouse R2, EBV R2 does not show a deuterium shift in the resonance Raman spectra. Thus, the presence of a water molecule as a hydrogen bond donor moiety could not be identified unequivocally. Theoretical simulations showed that a water molecule placed at a distance of 2.6 Å from the tyrosyl-oxygen does not result in a detectable deuterium shift in the calculated Raman spectra. UV/VIS light spectroscopic studies with metal chelators and tyrosyl radical scavengers are consistent with a more accessible dimetal binding/radical site and a lower affinity for Fe²⁺ in EBV R2 than in Escherichia coli R2. Comparison with previous studies of RNR R2s from mouse, bacteria, and herpes viruses, demonstrates that finely tuned electronic properties of the radical exist within the same RNR R2 Ia class.

Case Studies in e-RPL and e-PR

Science.gov (United States)

Cameron, Roslyn; Miller, Allison

2014-01-01

The use of ePortfolios for recognition of prior learning (e-RPL) and for professional recognition (e-PR) is slowly gaining in popularity in the VET sector however their use is sporadic across educational sectors, disciplines, educational institutions and professions. Added to this is an array of purposes and types of e-RPL and e-PR models and…

A Regional PD Strategy for EPR Systems: Evidence-Based IT Development

DEFF Research Database (Denmark)

Simonsen, Jesper; Hertzum, Morten

2006-01-01

One of the five regions in Denmark has initiated a remark-able and alternative strategy for the development of Elec-tronic Patient Record (EPR) systems. This strategy is driven by Participatory Design (PD) experiments and based on evidence of positive effects on the clinical practice when using EPR...... systems. We present this PD strategy and our related research on evidence-based IT development. We report from a newly completed PD experiment with EPR in the region conducted through a close collaboration compris-ing a neurological stroke unit, the region’s EPR unit, the vendor, as well as the authors....

EPR detection of free radicals in UV-irradiated skin: mouse versus human

International Nuclear Information System (INIS)

Jurkiewicz, B.A.; Buettner, G.R.

1996-01-01

Ultraviolet radiation produces free radicals in Skh-1 mouse skin, contributing to photoaging and carcinogenesis. If a mouse model is a general indicator of free radical processes in human skin photobiology, then radical production observed in mouse and human skin should be directly comparative. In this work we show that UV radiation (λ > 300 nm, 14 μW/cm 2 UVB; 3.5 mW/cm 2 UVA) increases the ascorbate free radical (Asc) electron paramagnetic resonance (EPR) signal in both Skh-1 mouse skin (45%) and human facial skin biopsies (340%). Visible light (λ > 400 nm; 0.23 mW/cm 2 UVA) also increased the Ascsignal in human skin samples (45%) but did not increase baseline mouse Asc, indicating that human skin is more susceptible to free radical formation and that a chromophore for visible light may be present. Using EPR spin-trapping techniques, UV radiation produced spin adducts consistent with trapping lipid alkyl radicals in mouse skin (α-[4-pyridyl 1-oxide]-N-tert-butyl nitrone/alkyl radical adduct; a N = 15.56 G and a H 2.70 G) and lipid alkoxyl radicals in human skin (5,5-dimethylpyrroline -1-oxide/alkoxyl radical adduct; a N = 14.54 G and a H = 16.0 G). Topical application of the iron chelator Desferal to human skin significantly decreases these radicals (∼50%), indicating a role for iron in lipid peroxidation. (Author)

Dosimetry of an accident in mixed field (neutrons, photons) using the spectrometry by electronic paramagnetic resonance(EPR)

International Nuclear Information System (INIS)

Herve, M.L.

2006-03-01

In a radiological accident, the assessment of the dose received by the victim is relevant information for the therapeutic strategy. Two complementary dosimetric techniques based on physical means are used in routine practice in the laboratory: EPR spectroscopy performed on materials removed from the victim or gathered from the vicinity of the victim and Monte Carlo calculations. EPR dosimetry, has been used successfully several times in cases of photon or electron overexposures. Accidental exposure may also occur with a neutron component. The aim of this work is to investigate the potentiality of EPR dosimetry for mixed photon and neutron field exposure with different organic materials (ascorbic acid, sorbitol, glucose, galactose, fructose, mannose, lactose and sucrose). The influence of irradiation parameters (dose, dose rate, photon energy) and of environmental parameters (temperature of heating, light exposure) on the EPR signal amplitude was studied. To assess the neutron sensitivity, the materials were exposed to a mixed radiation field of experimental reactors with different neutron to photon ratios. The relative neutron sensitivity was found to range from 10% to 43% according to the materials. Prior knowledge of the ratio between the dose in samples measured by EPR spectrometry and organ or whole body dose obtained by calculations previously performed for these different configurations, makes it possible to give a first estimation of the dose received by the victim in a short delay. The second aim of this work is to provide data relevant for a quick assessment of the dose distribution in case of accidental overexposure based on EPR measurements performed on one or several points of the body. The study consists in determining by calculation the relation between the dose to the organs and whole body and the dose to specific points of the body, like teeth, bones or samples located in the pockets of victim clothes, for different external exposures corresponding

Free-radical probes for functional in vivo EPR imaging

Science.gov (United States)

Subramanian, S.; Krishna, M. C.

2007-02-01

Electron paramagnetic resonance imaging (EPRI) is one of the recent functional imaging modalities that can provide valuable in vivo physiological information on its own merit and aids as a complimentary imaging technique to MRI and PET of tissues especially with respect to in vivo pO II (oxygen partial pressure), redox status and pharmacology. EPR imaging mainly deals with the measurement of distribution and in vivo dynamics and redox changes using special nontoxic paramagnetic spin probes that can be infused into the object of investigation. These spin probes should be characterized by simple EPR spectra, preferably with narrow EPR lines. The line width should be reversibly sensitive to the concentration of in vivo pO II with a linear dependence. Several non-toxic paramagnetic probes, some particulate and insoluble and others water-soluble and infusible (by intravenous or intramuscular injection) have been developed which can be effectively used to quantitatively assess tissue redox status, and tumor hypoxia. Quantitative assessment of the redox status of tissue in vivo is important in investigating oxidative stress, and that of tissue pO II is very important in radiation oncology. Other areas in which EPR imaging and oxymetry may help are in the investigation of tumorangiogenesis, wound healing, oxygenation of tumor tissue by the ingestion of oxygen-rich gases, etc. The correct choice of the spin probe will depend on the modality of measurement (whether by CW or time-domain EPR imaging) and the particular physiology interrogated. Examples of the available spin probes and some EPR imaging applications employing them are presented.

Confirmation of a second EPR to be built at Penly

International Nuclear Information System (INIS)

Anon.

2009-01-01

The French government has made public its decision to launch the construction of a second EPR in France. This EPR is planned to be built on the Penly site (northern region of France). EDF will manage this project but other investors like GDF-Suez are invited to participate. The construction works are planned to begin in 2012 for a commissioning in 2017. This reactor will be the fifth EPR being built in the world. (A.C.)

Nuclear spin-lattice relaxation in nitroxide spin-label EPR

DEFF Research Database (Denmark)

Marsh, Derek

2016-01-01

that the definition of nitrogen nuclear relaxation rate Wn commonly used in the CW-EPR literature for 14N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14N spin-lattice relaxation rate, b = Wn/(2We), preserves...... of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14N-relaxation: T1 n = 1/Wn. Results are compared and contrasted...

Applications of EPR steering in quantum teleportation and NOON states

Science.gov (United States)

Zárate, Laura Rosales

2018-04-01

Einstein-Podolsky-Rosen (EPR) steering refers to the type of correlations described in the EPR paradox, where one observer seems to affect ("steer") the state of other observer by using local measurements. There have been several works regarding characterization and quantification of EPR steering. One characteristic of this non-local correlation is that it can be asymmetric, while entanglement is symmetric. This asymmetric property is relevant for potential applications of EPR steering to quantum information, in particular to quantum cryptography and quantum teleportation. This latter refers to the process where one observer sends an unknown quantum state to Bob, who is in a different location. They communicate by classical means. Here we will show that EPR steering is a necessary resource to obtain secure continuous variable teleportation. We will also consider NOON states, which is an example of an entangled state. For this state, we will present a steering signature. This contribution reviews the work derived in Refs. [1] and [2], which was presented as an invited talk in ELAF 2017.

The use of deciduous molars in EPR dose reconstruction

International Nuclear Information System (INIS)

El-faramawy, N.A.; Wieser, A.

2005-01-01

The use of deciduous teeth in EPR dose reconstruction has the unique potential to measure individual doses that were accumulated in the early childhood in the age up to 12 years. It was found previously that due to the small size of deciduous incisors, the available amount of enamel is not sufficient for EPR measurements. Therefore, dose assessment with deciduous incisors can only be done by measurement of whole teeth, including enamel and dentine. The measurement of whole teeth instead of enamel alone is possibly less reliable for dose reconstruction because the stability of CO 2 - radicals (that are an indicator for the absorbed dose) in biologically active dentine is not known. In the present study naturally loosed deciduous molars were investigated. The feasibility of separating enamel from small size molars was analysed. EPR spectrum parameters of whole molars and separated enamel only were evaluated before and after laboratory irradiation. The EPR signal amplitudes of the CO 2 - and native signals were determined by spectrum deconvolution, in dependence on radiation dose in the range 0.1 - 10 Gy. The fading at room temperature of native and CO 2 - EPR signals was analysed. The detection threshold for absorbed dose in enamel was determined.

Uniform field loop-gap resonator and rectangular TEU02 for aqueous sample EPR at 94 GHz

Science.gov (United States)

Sidabras, Jason W.; Sarna, Tadeusz; Mett, Richard R.; Hyde, James S.

2017-09-01

In this work we present the design and implementation of two uniform-field resonators: a seven-loop-six-gap loop-gap resonator (LGR) and a rectangular TEU02 cavity resonator. Each resonator has uniform-field-producing end-sections. These resonators have been designed for electron paramagnetic resonance (EPR) of aqueous samples at 94 GHz. The LGR geometry employs low-loss Rexolite end-sections to improve the field homogeneity over a 3 mm sample region-of-interest from near-cosine distribution to 90% uniform. The LGR was designed to accommodate large degassable Polytetrafluorethylen (PTFE) tubes (0.81 mm O.D.; 0.25 mm I.D.) for aqueous samples. Additionally, field modulation slots are designed for uniform 100 kHz field modulation incident at the sample. Experiments using a point sample of lithium phthalocyanine (LiPC) were performed to measure both the uniformity of the microwave magnetic field and 100 kHz field modulation, and confirm simulations. The rectangular TEU02 cavity resonator employs over-sized end-sections with sample shielding to provide an 87% uniform field for a 0.1 × 2 × 6 mm3 sample geometry. An evanescent slotted window was designed for light access to irradiate 90% of the sample volume. A novel dual-slot iris was used to minimize microwave magnetic field perturbations and maintain cross-sectional uniformity. Practical EPR experiments using the application of light irradiated rose bengal (4,5,6,7-tetrachloro-2‧,4‧,5‧,7‧-tetraiodofluorescein) were performed in the TEU02 cavity. The implementation of these geometries providing a practical designs for uniform field resonators that continue resonator advancements towards quantitative EPR spectroscopy.

Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

Science.gov (United States)

Weber, Stefan; Kothe, Gerd; Norris, James R.

1997-04-01

The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave

Light-induced vegetative anthocyanin pigmentation in Petunia

OpenAIRE

Albert, Nick W.; Lewis, David H.; Zhang, Huaibi; Irving, Louis J.; Jameson, Paula E.; Davies, Kevin M.

2009-01-01

The Lc petunia system, which displays enhanced, light-induced vegetative pigmentation, was used to investigate how high light affects anthocyanin biosynthesis, and to assess the effects of anthocyanin pigmentation upon photosynthesis. Lc petunia plants displayed intense purple anthocyanin pigmentation throughout the leaves and stems when grown under high-light conditions, yet remain acyanic when grown under shade conditions. The coloured phenotypes matched with an accumulation of anthocyanins...

Spin entanglement, decoherence and Bohm's EPR paradox

OpenAIRE

Cavalcanti, E. G.; Drummond, P. D.; Bachor, H. A.; Reid, M. D.

2007-01-01

We obtain criteria for entanglement and the EPR paradox for spin-entangled particles and analyse the effects of decoherence caused by absorption and state purity errors. For a two qubit photonic state, entanglement can occur for all transmission efficiencies. In this case, the state preparation purity must be above a threshold value. However, Bohm's spin EPR paradox can be achieved only above a critical level of loss. We calculate a required efficiency of 58%, which appears achievable with cu...

Comparison of continuous wave, spin echo, and rapid scan EPR of irradiated fused quartz

International Nuclear Information System (INIS)

Mitchell, Deborah G.; Quine, Richard W.; Tseitlin, Mark; Meyer, Virginia; Eaton, Sandra S.; Eaton, Gareth R.

2011-01-01

The E' defect in irradiated fused quartz has spin lattice relaxation times (T 1 ) about 100-300 μs and spin-spin relaxation times (T 2 ) up to about 200 μs, depending on the concentration of defects and other species in the sample. These long relaxation times make it difficult to record an unsaturated continuous wave (CW) electron paramagnetic resonance (EPR) signal that is free of passage effects. Signals measured at X-band (∼9.5 GHz) by three EPR methods: conventional slow-scan field-modulated EPR, rapid scan EPR, and pulsed EPR, were compared. To acquire spectra with comparable signal-to-noise, both pulsed and rapid scan EPR require less time than conventional CW EPR. Rapid scan spectroscopy does not require the high power amplifiers that are needed for pulsed EPR. The pulsed spectra, and rapid scan spectra obtained by deconvolution of the experimental data, are free of passage effects.

Saturation recovery EPR spin-labeling method for quantification of lipids in biological membrane domains.

Science.gov (United States)

Mainali, Laxman; Camenisch, Theodore G; Hyde, James S; Subczynski, Witold K

2017-12-01

The presence of integral membrane proteins induces the formation of distinct domains in the lipid bilayer portion of biological membranes. Qualitative application of both continuous wave (CW) and saturation recovery (SR) electron paramagnetic resonance (EPR) spin-labeling methods allowed discrimination of the bulk, boundary, and trapped lipid domains. A recently developed method, which is based on the CW EPR spectra of phospholipid (PL) and cholesterol (Chol) analog spin labels, allows evaluation of the relative amount of PLs (% of total PLs) in the boundary plus trapped lipid domain and the relative amount of Chol (% of total Chol) in the trapped lipid domain [ M. Raguz, L. Mainali, W. J. O'Brien, and W. K. Subczynski (2015), Exp. Eye Res., 140:179-186 ]. Here, a new method is presented that, based on SR EPR spin-labeling, allows quantitative evaluation of the relative amounts of PLs and Chol in the trapped lipid domain of intact membranes. This new method complements the existing one, allowing acquisition of more detailed information about the distribution of lipids between domains in intact membranes. The methodological transition of the SR EPR spin-labeling approach from qualitative to quantitative is demonstrated. The abilities of this method are illustrated for intact cortical and nuclear fiber cell plasma membranes from porcine eye lenses. Statistical analysis (Student's t -test) of the data allowed determination of the separations of mean values above which differences can be treated as statistically significant ( P ≤ 0.05) and can be attributed to sources other than preparation/technique.

Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy

International Nuclear Information System (INIS)

Hayes, Robert B.; Haskell, E.H.; Wieser, Albrecht; Romanyukha, Alexander A.; Hardy, Byron L.; Barrus, Jeffrey K.

2000-01-01

Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01-1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3% over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration

Assessment of an alanine EPR dosimetry technique with enhanced precision and accuracy

CERN Document Server

Hayes, R B; Wieser, A; Romanyukha, A A; Hardy, B L; Barrus, J K

2000-01-01

Dose reconstruction in the course of a series of blind tests demonstrated that an accuracy of 10 mGy for low doses and 1% for high doses can be achieved using EPR spectroscopy. This was accomplished using a combination of methodologies including polynomial filtration of the EPR spectrum, dosimeter rotation during scanning, use of an EPR standard fixed into the resonator and subtraction of all nonradiogenic signals. Doses were reconstructed over the range of 0.01-1000 Gy using this compound spectral EPR analysis. This EPR technique, being equally applicable to fractionated doses (such as those delivered during multiple radiotherapy treatments), was verified to exhibit dose reciprocity. Irradiated alanine dosimeters which were stored exhibited compound spectral EPR signal fading of ca 3% over 9 months. All error estimates given in this paper are given at the 1 standard deviation level and unless otherwise specified do not account for uncertainties in source calibration.

A Local Realistic Reconciliation of the EPR Paradox

Science.gov (United States)

Sanctuary, Bryan

2014-03-01

The exact violation of Bell's Inequalities is obtained with a local realistic model for spin. The model treats one particle that comprises a quantum ensemble and simulates the EPR data one coincidence at a time as a product state. Such a spin is represented by operators σx , iσy ,σz in its body frame rather than the usual set of σX ,σY ,σZ in the laboratory frame. This model, assumed valid in the absence of a measuring probe, contains both quantum polarizations and coherences. Each carries half the EPR correlation, but only half can be measured using coincidence techniques. The model further predicts the filter angles that maximize the spin correlation in EPR experiments.

Antibacterial ethylene propylene rubber impregnated with silver nanopowder: AgNP@EPR

Directory of Open Access Journals (Sweden)

Marzieh Miranzadeh

2016-01-01

Full Text Available Following our interest in reaching for a molded rubber article with possible detergent contact applications, durable silver nanopowder (AgNP is synthesized by arc discharge, then mixed with varying ratios of ethylene propylene rubber (EPR, affording novel AgNP@EPR nanocomposites. X-ray diffraction (XRD patterns of AgNP as well as AgNP@EPR show no trace of impurity, while scanning electron microscopy (SEM indicates an average diameter of 50 nm for the former. Transmission electron microscopy (TEM images while confirm the SEM results, show quite a few 5 nm AgNP particles lying beside some micro crumbs. Our DC arc discharge technique involves explosion of movable silver anode and static cathode by a current pulse between 5 to 10 A cm-2. A solution blending method is employed for preparation of AgNP@EPR nanocomposites. The AgNP is first dispersed in toluene using an ultrasonic homogenizer, and then thoroughly mixed with EPR in the same solvent whose removal gives nanocomposites of 2, 4, 6 and 8 vol% AgNP in EPR,  showing strong antibacterial activity against both Escherichia coli and Staphylococcus aureus.

Alanine EPR dosimetry of therapeutic irradiators

International Nuclear Information System (INIS)

Bugay, O.; Bartchuk, V.; Kolesnik, S.; Mazin, M.; Gaponenko, H.

1999-01-01

The high-dose alanine EPR dosimetry is a very precise method in the dose range 1-100 kGy. The system is used generally as the standard high-dose transfer dosimetry in many laboratories. This is comparatively expensive technique so it is important to use it as a more universal dosimetry system also in the middle and low dose ranges. The problems of the middle-dose alanine dosimetry are discussed and the solution of several problems is proposed. The alanine EPR dosimetry has been applied to the dose measurements of medical irradiators in the Kiev City Oncology Center. (author)

EPR Study of [Cu(Him)4]·2Br Complex

International Nuclear Information System (INIS)

Yıldırım, İ; Karabulut, B

2016-01-01

The single crystal of [Cu(Him) 4 ]·2Br (Him: C 3 H 4 N 2 , imidazole) complex has been investigated at ambient temperature in three mutually perpendicular planes by EPR technique. The magnetic environments of [Cu(Him) 4 ]·2Br complex have been identified by EPR technique. The study reveals the existence of two magnetically inequivalent Cu 2+ sites. The principal values of g tensors were obtained. The EPR parameters show that the paramagnetic centers have rhombic symmetry. (paper)

Pulse EPR distance measurements to study multimers and multimerisation

Science.gov (United States)

Ackermann, Katrin; Bode, Bela E.

2018-06-01

Pulse dipolar electron paramagnetic resonance (PD-EPR) has become a powerful tool for structural biology determining distances on the nanometre scale. Recent advances in hardware, methodology, and data analysis have widened the scope to complex biological systems. PD-EPR can be applied to systems containing lowly populated conformers or displaying large intrinsic flexibility, making them all but intractable for cryo-electron microscopy and crystallography. Membrane protein applications are of particular interest due to the intrinsic difficulties for obtaining high-resolution structures of all relevant conformations. Many drug targets involved in critical cell functions are multimeric channels or transporters. Here, common approaches for introducing spin labels for PD-EPR cause the presence of more than two electron spins per multimeric complex. This requires careful experimental design to overcome detrimental multi-spin effects and to secure sufficient distance resolution in presence of multiple distances. In addition to obtaining mere distances, PD-EPR can also provide information on multimerisation degrees allowing to study binding equilibria and to determine dissociation constants.

Photoreactivation of ultraviolet light-induced sister chromatid exchanges in potorous cells

International Nuclear Information System (INIS)

Ishizaki, K.; Nikaido, O.; Takebe, H.

1980-01-01

Exposure to visible light after UV-irradiation showed a remarkable effect on UV-induced sister chromatid exchanges (SCEs). After 6-h exposure to visible light (3 x 10 5 J/m 2 ), two-thirds of the UV-induced SCEs were prevented, confirming Kato's findings. (Nature 249, 552-3, 1974) Exposure to visible light before UV irradiation had no effect. This effect of visible light on UV-induced CSEs was temperature dependent, suggesting the presence of enzymatic photoreactivation. (author)

Light-induced ion-acoustic instability of rarefied plasma

International Nuclear Information System (INIS)

Krasnov, I.V.; Sizykh, D.V.

1987-01-01

A new method of ion-acoustic instability excitation under the effect of coherent light, resonance to ion quantum transitions on collisionless plasma, is suggested. The light-induced ion-acoustic instability (LIIAI) considered is based on the induced progressive nonequilibrium resonance particles in the field of travelling electromagnetic wave. Principal possibility to use LIIAI in high-resolution spectroscopy and in applied problems of plasma physics, related to its instability, is pointed out

EPR Imaging at a Few Megahertz Using SQUID Detectors

Science.gov (United States)

Hahn, Inseob; Day, Peter; Penanen, Konstantin; Eom, Byeong Ho

2010-01-01

An apparatus being developed for electron paramagnetic resonance (EPR) imaging operates in the resonance-frequency range of about 1 to 2 MHz well below the microwave frequencies used in conventional EPR. Until now, in order to obtain sufficient signal-to-noise radios (SNRs) in conventional EPR, it has been necessary to place both detectors and objects to be imaged inside resonant microwave cavities. EPR imaging has much in common with magnetic resonance imaging (MRI), which is described briefly in the immediately preceding article. In EPR imaging as in MRI, one applies a magnetic pulse to make magnetic moments (in this case, of electrons) precess in an applied magnetic field having a known gradient. The magnetic moments precess at a resonance frequency proportional to the strength of the local magnetic field. One detects the decaying resonance-frequency magnetic- field component associated with the precession. Position is encoded by use of the known relationship between the resonance frequency and the position dependence of the magnetic field. EPR imaging has recently been recognized as an important tool for non-invasive, in vivo imaging of free radicals and reduction/oxidization metabolism. However, for in vivo EPR imaging of humans and large animals, the conventional approach is not suitable because (1) it is difficult to design and construct resonant cavities large enough and having the required shapes; (2) motion, including respiration and heartbeat, can alter the resonance frequency; and (3) most microwave energy is absorbed in the first few centimeters of tissue depth, thereby potentially endangering the subject and making it impossible to obtain adequate signal strength for imaging at greater depth. To obtain greater penetration depth, prevent injury to the subject, and avoid the difficulties associated with resonant cavities, it is necessary to use lower resonance frequencies. An additional advantage of using lower resonance frequencies is that one can use

A high-frequency EPR study of a new S = 10 Mn12 single-molecule magnet

Science.gov (United States)

Anderson, Norm

2005-03-01

We will present a detailed angle-resolved high-frequency EPR study of a recently discovered analog of the Mn12-acetate single-molecule magnet (SMM). Like the acetate, the new complex [Mn12O12(O2CCH2Bu^t)16(CH3OH)4].CH3OH (Mn12-tBuAc), possesses a spin S = 10 ground state and S4 site symmetry. Magnetic measurements also reveal the usual resonant magnetization tunneling steps in the low temperature hysteresis loops. However, we show that the solvent-disorder-induced anomalies reported in the EPR spectra for Mn12-acetate^1 are absent for Mn12-tBuAc. This suggests that Mn12-tBuAc is intrinsically cleaner, and that detailed studies of this compound may reveal important new information concerning the quantum dynamics of large spins. Indeed, our analysis of the EPR line widths suggest that they are close to the intrinsic lifetime broadened limit, which may make it possible to extract information concerning electronic relaxation times (T1 and T2). ^1S. Takahashi et al., Phys. Rev. B 70, 094429 (2004)

Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR-CAT)

Science.gov (United States)

2015-10-01

Award Number: W81XWH-07-1-0682 TITLE: Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma ( EPR -CAT) PRINCIPAL INVESTIGATOR...thoracotomy and open chest CPR, results in unacceptably low survival rates. Emergency Preservation and Resuscitation ( EPR ) was developed to rapidly preserve...further recommended that the trauma surgeons involved in the study obtain hospital privileges for cannulation for the EPR flush. This has been

Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma (EPR CAT)

Science.gov (United States)

2016-12-01

Award Number: W81XWH-07-1-0682 TITLE: Emergency Preservation and Resuscitation for Cardiac Arrest from Trauma ( EPR -CAT) PRINCIPAL INVESTIGATOR...Preservation and Resuscitation ( EPR ) was developed to rapidly preserve the organism during ischemia, using hypothermia, drugs, and fluids, to “buy time...privileges for cannulation for the EPR flush. This has been accomplished. Given the complexity of our planned intervention for trauma patients in

Optimal registration conditions for tooth EPR dosimetry at low accumulated dose

International Nuclear Information System (INIS)

Galtsev, V.E.; Galtseva, E.V.; Lebedev, Y.S.

1997-01-01

The spectrum registration under rapid passage conditions (the second harmonic phase quadrature of the absorption signal) allows one to enhance substantially the sensitivity of tooth enamel and bone EPR dosimetry at a low accumulated dose. In the present work the dependencies of the radiation and background signals on EPR spectrometer parameters are described and the optimal conditions in RPM for EPR dosimetry are obtained. (Author)

Wormhole and entanglement (non-)detection in the ER=EPR correspondence

Energy Technology Data Exchange (ETDEWEB)

Bao, Ning [Institute for Quantum Information and Matter, California Institute of Technology,Pasadena, CA 91125 (United States); Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States); Pollack, Jason; Remmen, Grant N. [Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States)

2015-11-19

The recently proposed ER=EPR correspondence postulates the existence of wormholes (Einstein-Rosen bridges) between entangled states (such as EPR pairs). Entanglement is famously known to be unobservable in quantum mechanics, in that there exists no observable (or, equivalently, projector) that can accurately pick out whether a generic state is entangled. Many features of the geometry of spacetime, however, are observables, so one might worry that the presence or absence of a wormhole could identify an entangled state in ER=EPR, violating quantum mechanics, specifically, the property of state-independence of observables. In this note, we establish that this cannot occur: there is no measurement in general relativity that unambiguously detects the presence of a generic wormhole geometry. This statement is the ER=EPR dual of the undetectability of entanglement.

Wormhole and entanglement (non-)detection in the ER=EPR correspondence

International Nuclear Information System (INIS)

Bao, Ning; Pollack, Jason; Remmen, Grant N.

2015-01-01

The recently proposed ER=EPR correspondence postulates the existence of wormholes (Einstein-Rosen bridges) between entangled states (such as EPR pairs). Entanglement is famously known to be unobservable in quantum mechanics, in that there exists no observable (or, equivalently, projector) that can accurately pick out whether a generic state is entangled. Many features of the geometry of spacetime, however, are observables, so one might worry that the presence or absence of a wormhole could identify an entangled state in ER=EPR, violating quantum mechanics, specifically, the property of state-independence of observables. In this note, we establish that this cannot occur: there is no measurement in general relativity that unambiguously detects the presence of a generic wormhole geometry. This statement is the ER=EPR dual of the undetectability of entanglement.

In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR oximetry

Science.gov (United States)

Weaver, John; Yang, Yirong; Purvis, Rebecca; Weatherwax, Theodore; Rosen, Gerald M.; Liu, Ke Jian

2014-01-01

Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O2 may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O2 is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO2 in vivo remains largely uncharacterized. This study investigated striatal tissue pO2 changes in male C57BL/6 mice (16–20g) following METH administration using EPR oximetry, a highly sensitive modality to measure pO2 in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO2 was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO2 to 64%. More importantly, pO2 did not recover fully to control levels even 24 hrs after administration of a single dose of METH. and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO2 indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO2, which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. PMID:24412707

Perspectives of shaped pulses for EPR spectroscopy

Science.gov (United States)

Spindler, Philipp E.; Schöps, Philipp; Kallies, Wolfgang; Glaser, Steffen J.; Prisner, Thomas F.

2017-07-01

This article describes current uses of shaped pulses, generated by an arbitrary waveform generator, in the field of EPR spectroscopy. We show applications of sech/tanh and WURST pulses to dipolar spectroscopy, including new pulse schemes and procedures, and discuss the more general concept of optimum-control-based pulses for applications in EPR spectroscopy. The article also describes a procedure to correct for experimental imperfections, mostly introduced by the microwave resonator, and discusses further potential applications and limitations of such pulses.

Dependencies of the radiation sensitivity of human tooth enamel in EPR dosimetry

International Nuclear Information System (INIS)

Wieser, A.; El-Faramawy, N.; Meckbach, R.

2001-01-01

The EPR dose response of tooth enamel was determined for human molars collected in Egypt. The influence of age, gender and residence of the tooth donors as well as tooth position and sample preparation on EPR sensitivity and its variability over the enamel samples was investigated. The EPR sensitivity and its variability were found to depend only on the sample preparation procedure. The variability in EPR sensitivity of enamel from Egyptian teeth was maximally 10% and the mean sensitivity was in good agreement with that of German teeth

Photochemical reduction of water-soluble C60 derivatives (EPR study)

International Nuclear Information System (INIS)

Brezova, V.; Stasko, A.; Dvoranova, D.; Asmus, K.D.; Guldi, D.M.

1999-01-01

The photochemical reduction of three bis-functionalized C 60 derivatives resulted in the formation of a single radical product, characterized by relatively narrow EPR line (g M = 2.0007, pp < 0.02 mT). In the irradiated aqueous solutions containing L-ascorbic acid, in the addition to the EPR line related to bis-adduct mono-anion, also 6-line EPR spectrum of ascorbyl radical was observed. Consequently, the photoinduced formation of ascorbyl radical was attributed to the intermolecular quenching of fullerenes excited states. (authors)

Investigating Pigment Radicals in Black Rice Using HPLC and Multi-EPR.

Science.gov (United States)

Nakagawa, Kouichi; Maeda, Hayato

2017-01-01

We investigated the location and distribution of paramagnetic species in black and white rice using electron paramagnetic resonance (EPR), X-band (9 GHz) EPR imaging (EPRI), and HPLC. EPR primarily detected two paramagnetic species in black rice, which were identified as a stable radical and Mn 2+ species, based on the g values and hyperfine components of the EPR signals. The signal from the stable radical appeared at g ≈ 2.00 and was relatively strong and stable. Subsequent noninvasive two-dimensional (2D) EPRI revealed that this stable radical was primarily located in the pigmented region of black rice, while very few radicals were observed in the rice interior. Pigments extracted from black rice were analyzed using HPLC; the major compound was found to be cyanidin-3-glucoside. EPR and HPLC results indicate that the stable radical was only found within the pigmented region of the rice, and that it could either be cyanidin-3-glucoside, or one of its oxidative decomposition products.

Use of rapid-scan EPR to improve detection sensitivity for spin-trapped radicals.

Science.gov (United States)

Mitchell, Deborah G; Rosen, Gerald M; Tseitlin, Mark; Symmes, Breanna; Eaton, Sandra S; Eaton, Gareth R

2013-07-16

The short lifetime of superoxide and the low rates of formation expected in vivo make detection by standard continuous wave (CW) electron paramagnetic resonance (EPR) challenging. The new rapid-scan EPR method offers improved sensitivity for these types of samples. In rapid-scan EPR, the magnetic field is scanned through resonance in a time that is short relative to electron spin relaxation times, and data are processed to obtain the absorption spectrum. To validate the application of rapid-scan EPR to spin trapping, superoxide was generated by the reaction of xanthine oxidase and hypoxanthine with rates of 0.1-6.0 μM/min and trapped with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO). Spin trapping with BMPO to form the BMPO-OOH adduct converts the very short-lived superoxide radical into a more stable spin adduct. There is good agreement between the hyperfine splitting parameters obtained for BMPO-OOH by CW and rapid-scan EPR. For the same signal acquisition time, the signal/noise ratio is >40 times higher for rapid-scan than for CW EPR. Rapid-scan EPR can detect superoxide produced by Enterococcus faecalis at rates that are too low for detection by CW EPR. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Peptide-membrane Interactions by Spin-labeling EPR

Science.gov (United States)

Smirnova, Tatyana I.; Smirnov, Alex I.

2016-01-01

Site-directed spin labeling (SDSL) in combination with Electron Paramagnetic Resonance (EPR) spectroscopy is a well-established method that has recently grown in popularity as an experimental technique, with multiple applications in protein and peptide science. The growth is driven by development of labeling strategies, as well as by considerable technical advances in the field, that are paralleled by an increased availability of EPR instrumentation. While the method requires an introduction of a paramagnetic probe at a well-defined position in a peptide sequence, it has been shown to be minimally destructive to the peptide structure and energetics of the peptide-membrane interactions. In this chapter, we describe basic approaches for using SDSL EPR spectroscopy to study interactions between small peptides and biological membranes or membrane mimetic systems. We focus on experimental approaches to quantify peptide-membrane binding, topology of bound peptides, and characterize peptide aggregation. Sample preparation protocols including spin-labeling methods and preparation of membrane mimetic systems are also described. PMID:26477253

Metastable light induced defects in pentacene

Energy Technology Data Exchange (ETDEWEB)

Liguori, R.; Aprano, S.; Rubino, A. [Department of Industrial Engineering (DIIn), University of Salerno, via Giovanni Paolo II, 132, 84084 Fisciano (Italy)

2014-02-21

In this study we analyzed one of the environmental factors that could affect organic materials. Pentacene thin film samples were fabricated and the degradation of their electrical characteristics was measured when the devices were exposed to ultraviolet light irradiation. The results have been reported in terms of a trap density model, which provides a description of the dynamics of light induced electrically active defects in an organic semiconductor.

On the Correlations between the Particles in the EPR-Paradoxon

Science.gov (United States)

Treder, H.-J.

The Einstein-Podolsky-Rosen gedanken-experiment does not imply non-local interactions or an action-at-a-distance.Contrary, the EPR proves the measurements at one particle does not have influences at canonical variables of the other particles if the quantum-mechanical commutation relations are true.But, the EPR implices correlations between the particles which come in by subjective knowledge. These correlations are a priori informations about the relative motion or, complementarily, about the motion of the center of mass. The impression of an action-at-a-distance is produced by the use of usual particle coordinates in the EPR-arrangements.The discussion of the Einstein-Podolsky-Rosen gedanken-experiment (EPR) has been going on over fifty years. EINSTEIN, PODOLSKY, and ROSEN formulated their famous paradox in 1935, and in the discussion between N. BOHR (1935, 1949) and A. EINSTEIN (1936, 1948); A. EINSTEIN (1948) made his point that the EPR implied an action-at-a-distance for quantum-mechanical particles (without obvious classical interactions). His argument is the starting point for the recent discussion about EPR and causality (see A. Aspect, 1981).Translated AbstractÜber die Korrelationen zwischen den Partikeln beim EPR-ParadoxonDas Gedankenexperiment von EINSTEIN, PODOLSKY und ROSEN über die anscheinend paradoxen Beziehungen zwischen beliebig weit entfernten Partikeln gemäß der quantenmechanischen Theorie der Messungen führt tatsächlich nicht auf nichtlokale Wechselwirkungen.Das Einstein-Podolsky-Rosen-Paradoxon zeigt vielmehr, daß die Messung an einem Teilchen keinerlei Einfluß auf die Meßwerte an anderen Partikeln hat, wenn die quantenmechanischen Vertauschungsregeln erfüllt sind.Dagegen weist das Einstein-Podolsky-Rosensche Gedankenexperiment Korrelationen zwischen den Teilchen auf, die die Folge einer a-priori-Kenntnis über die Werte von Hamilton-Jacobischen Zwei-Partikeln-Koordinaten von nicht-wechselwirkenden Teilchen sind.

Multi-photon transitions and Rabi resonance in continuous wave EPR.

Science.gov (United States)

Saiko, Alexander P; Fedaruk, Ryhor; Markevich, Siarhei A

2015-10-01

The study of microwave-radiofrequency multi-photon transitions in continuous wave (CW) EPR spectroscopy is extended to a Rabi resonance condition, when the radio frequency of the magnetic-field modulation matches the Rabi frequency of a spin system in the microwave field. Using the non-secular perturbation theory based on the Bogoliubov averaging method, the analytical description of the response of the spin system is derived for all modulation frequency harmonics. When the modulation frequency exceeds the EPR linewidth, multi-photon transitions result in sidebands in absorption EPR spectra measured with phase-sensitive detection at any harmonic. The saturation of different-order multi-photon transitions is shown to be significantly different and to be sensitive to the Rabi resonance. The noticeable frequency shifts of sidebands are found to be the signatures of this resonance. The inversion of two-photon lines in some spectral intervals of the out-of-phase first-harmonic signal is predicted under passage through the Rabi resonance. The inversion indicates the transition from absorption to stimulated emission or vice versa, depending on the sideband. The manifestation of the primary and secondary Rabi resonance is also demonstrated in the time evolution of steady-state EPR signals formed by all harmonics of the modulation frequency. Our results provide a theoretical framework for future developments in multi-photon CW EPR spectroscopy, which can be useful for samples with long spin relaxation times and extremely narrow EPR lines. Copyright © 2015 Elsevier Inc. All rights reserved.

Light-dependent expression of flg22-induced defense genes in Arabidopsis

Directory of Open Access Journals (Sweden)

Satoshi eSano

2014-10-01

Full Text Available Chloroplasts have been reported to generate retrograde immune signals that activate defense gene expression in the nucleus. However, the roles of light and photosynthesis in plant immunity remain largely elusive. In this study, we evaluated the effects of light on the expression of defense genes induced by flg22, a peptide derived from bacterial flagellins which acts as a potent elicitor in plants. Whole-transcriptome analysis of flg22-treated Arabidopsis thaliana seedlings under light and dark conditions for 30 min revealed that a number of (30% genes strongly induced by flg22 (>4.0 require light for their rapid expression, whereas flg22-repressed genes include a significant number of genes that are down-regulated by light. Furthermore, light is responsible for the flg22-induced accumulation of salicylic acid, indicating that light is indispensable for basal defense responses in plants. To elucidate the role of photosynthesis in defense, we further examined flg22-induced defense gene expression in the presence of specific inhibitors of photosynthetic electron transport: 3-(3,4-dichlorophenyl-1,1-dimethylurea (DCMU and 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB. Light-dependent expression of defense genes was largely suppressed by DBMIB, but only partially suppressed by DCMU. These findings suggest that photosynthetic electron flow plays a role in controling the light-dependent expression of flg22-inducible defense genes.

Decomposition of spectra in EPR dosimetry using the matrix method

International Nuclear Information System (INIS)

Sholom, S.V.; Chumak, V.V.

2003-01-01

The matrix method of EPR spectra decomposition is developed and adapted for routine application in retrospective EPR dosimetry with teeth. According to this method, the initial EPR spectra are decomposed (using methods of matrix algebra) into several reference components (reference matrices) that are specific for each material. Proposed procedure has been tested on the example of tooth enamel. Reference spectra were a spectrum of an empty sample tube and three standard signals of enamel (two at g=2.0045, both for the native signal and one at g perpendicular =2.0018, g parallel =1.9973 for the dosimetric signal). Values of dosimetric signals obtained using the given method have been compared with data obtained by manual manipulation of spectra, and good coincidence was observed. This allows considering the proposed method as potent for application in routine EPR dosimetry

EPR (European Pressurized Reactor)

International Nuclear Information System (INIS)

2015-01-01

This document presents the EPR (European Pressurized Reactor), a modernised version of PWRs which uses nuclear fission. It indicates to which category it belongs (third generation). It briefly describes its operation: recalls on nuclear fission, electricity production in a nuclear reactor. It presents and comments its characteristics: power, thermal efficiency, redundant systems for safety control, double protective enclosure, expected lifetime, use of MOX fuel, modular design. It discusses economic stakes (expected higher nuclear electricity competitiveness, but high construction costs), and safety challenges (design characteristics, critics by nuclear safety authorities about the safety data processing system). It presents the main involved actors (Areva, EDF) and competitors in the field of advanced reactors (Rosatom with its VVER 1200, General Electric with its ABWR and its ESBWR, Mitsubishi with its APWR, Westinghouse with its AP100) while outlining the importance of certifications and delays to obtain them. After having evoked key data on EPR fuel consumption, it indicates reactors under construction, evokes potential markets and perspectives

EPR study of the production of OH radicals in aqueous solutions of uranium irradiated by ultraviolet light

Directory of Open Access Journals (Sweden)

MARKO DAKOVIĆ

2009-06-01

Full Text Available The aim of the study was to establish whether hydroxyl radicals (•OH were produced in UV-irradiated aqueous solutions of uranyl salts. The production of •OH was studied in uranyl acetate and nitrate solutions by an EPR spin trap method over a wide pH range, with variation of the uranium concentrations. The production of •OH in uranyl solutions irradiated with UV was unequivocally demonstrated for the first time using the EPR spin-trapping method. The production of •OH can be connected to speciation of uranium species in aqueous solutions, showing a complex dependence on the solution pH. When compared with the results of radiative de-excitation of excited uranyl (*UO22+ by the quenching of its fluorescence, the present results indicate that the generation of hydroxyl radicals plays a major role in the fluorescence decay of *UO22+. The role of the presence of carbonates and counter ions pertinent to environmental conditions in biological systems on the production of hydroxyl radicals was also assessed in an attempt to reveal the mechanism of *UO22+ de-excitation. Various mechanisms, including •OH production, are inferred but the main point is that the generation of •OH in uranium containing solutions must be considered when assessing uranium toxicity.

Identification of irradiated crab using EPR

Energy Technology Data Exchange (ETDEWEB)

Maghraby, A. [Radiation Dosimetry Department, National Institute for Standards (NIS), Ministry of Scientific Research, Haram, 12211- Giza, P.O. Box: 136 (Egypt)]. E-mail: maghrabism@yahoo.com

2007-02-15

EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156-5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response.

Krótka (prehistoria argumentu EPR

Directory of Open Access Journals (Sweden)

Tadeusz Pabjan

2010-12-01

Full Text Available The 1935 thought experiment of Einstein, Podolsky and Rosen is one of the most important episodes in the history of the dispute about the correct interpretation of quantum mechanics. The present paper deals with the origin of the EPR paper and discusses some other thought experiments that preceded the formulation of the Einstein-Podolsky-Rosen argument. Special attention is paid to the evolution of a simply photon-box experiment, which was devised by Einstein in 1930 and then modified by him several times before 1935. It is argued that the scheme of the original EPR argument is in fact contained in these few seminal experiments.

Identification of irradiated crab using EPR

International Nuclear Information System (INIS)

Maghraby, A.

2007-01-01

EPR spectroscopy is a fast and powerful technique for the identification of irradiated food. Crab exoskeleton was divided into six parts: dactyl, cheliped, carapace, apron, swimming legs, and walking legs. Samples of the exoskeleton were prepared and irradiated to Cs-137 gamma radiation in the range (1.156-5.365 kGy). EPR spectra of unirradiated as well as irradiated samples were recorded and analyzed. Response to gamma radiation was plotted for each part of the exoskeleton, dactyl was found to be the most sensitive part, followed by the apron (38%), cheliped (37%), walking legs (30%), swimming legs (24%), and carapace (21%) relative to the dactyl response

Mast-sipping in EPR trademark plants

International Nuclear Information System (INIS)

Langenberger, Jan; Schienbein, Marcel; Geier, Roland

2010-01-01

For more than 20 years, AREVA applies and develops different sipping techniques to identify fuel assemblies with leaking fuel rods. For the EPR trademark reactors a Mast Sipping System with newest developments will be implemented considering radiation protection and latest standards requirements. The innovative EPR trademark Sipping System differs from previous systems in many ways. One of the main innovations is that all the necessary processes of the Sipping system have been fully digitized. Second, several ALARA design modifications have been implemented to meet the current radiation protection requirements. An additional implementable multilingual assistance program facilitates the handling of the system and helps to prevent incorrect operation. (orig.)

Radicals as EPR probes of magnetization of gadolinium stearate Langmuir-Blodgett film

DEFF Research Database (Denmark)

Koksharov, Y.A.; Bykov, I.V.; Malakho, A.P.

2002-01-01

In the present work we have applied the method of the EPR spin probes which allows performing simultaneously EPR and magnetization measurements to the investigation of magnetism of the Cid stearate Langmuir-Blodgett (LB) films. For this purpose we have prepared and studied by the EPR technique...... the Gd and Y stearate LB films. Placing the small BDPA crystal on the film surface we have found that for the Gd LB sample the effective g-value of the radical's resonance depends on the film orientation in respect to the external magnetic field direction. The relative shift of the EPR signal...

l-Serine Enhances Light-Induced Circadian Phase Resetting in Mice and Humans.

Science.gov (United States)

Yasuo, Shinobu; Iwamoto, Ayaka; Lee, Sang-Il; Ochiai, Shotaro; Hitachi, Rina; Shibata, Satomi; Uotsu, Nobuo; Tarumizu, Chie; Matsuoka, Sayuri; Furuse, Mitsuhiro; Higuchi, Shigekazu

2017-12-01

Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Methods: Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before l-serine administration, and light-induced phase shifts were analyzed. In addition, the effect of l-serine on the light-induced phase advance was investigated in healthy male students (mean ± SD age 22.2 ± 1.8 y) by using dim-light melatonin onset (DLMO) determined by saliva samples as an index of the circadian phase. Results: l-Serine administration enhanced light-induced phase shifts in mice (1.86-fold; P light-dark cycle by 6 h, l-serine administration slightly accelerated re-entrainment to the shifted cycle. In humans, l-serine ingestion before bedtime induced significantly larger phase advances of DLMO after bright-light exposure during the morning (means ± SEMs-l-serine: 25.9 ± 6.6 min; placebo: 12.1 ± 7.0 min; P light-induced phase resetting in mice and humans, and it may be useful for treating circadian disturbances. © 2017 American Society for Nutrition.

EPR: The reactor generation for the 21st century. SFEN-KTG congress 'The EPR Project'', Strasbourg, 13-14 Nov. 1994

International Nuclear Information System (INIS)

Anon.

1995-01-01

The foundation of the subsidiary in 1989, Nuclear Power International (NPI), brought together as partners the two formerly competing companies Siemens/KWU and Framatome who now are planning the novel reactor type within the framework of the joint EPR project. The project goal is to develop a novel French-German PWR reactor type for power generation, named European Pressurized Water Reactor (EPR). The article summarizes the main results of papers and discussions of the congress. (orig./UA) [de

Which Parts of a Clinical Process EPR Needs Special Configuration

DEFF Research Database (Denmark)

Barlach, Anders; Simonsen, Jesper

2007-01-01

Subject: Which parts of an electronic patient record (EPR) can initially form a stable standard solution to be used by all clinicians? And which parts of an EPR can we predict needs initial as well as on-going re-configuration to meet the needs from diverse medical specialties. Purpose: To analyze...... which screen types in a clinical process that can be standard configured and which are subject to initial as well as on-going re-configuration. Methods and results: A pilot-project implementing a fully functional clinical process EPR was configured and used at a neurological ward, replacing all paper...... records 24/7. The analysis characterizes the different types of screens, a total of 243 included in the EPR solution. All screens have been extracted from the application and analyzed for changes – in total 222 changes. Discussion and conclusion: Most screens (87%) are very stable. Few (13%) are subjected...

Biophysical EPR Studies Applied to Membrane Proteins

Science.gov (United States)

Sahu, Indra D; Lorigan, Gary A

2015-01-01

Membrane proteins are very important in controlling bioenergetics, functional activity, and initializing signal pathways in a wide variety of complicated biological systems. They also represent approximately 50% of the potential drug targets. EPR spectroscopy is a very popular and powerful biophysical tool that is used to study the structural and dynamic properties of membrane proteins. In this article, a basic overview of the most commonly used EPR techniques and examples of recent applications to answer pertinent structural and dynamic related questions on membrane protein systems will be presented. PMID:26855825

75 FR 4882 - Meeting of the ACRS Subcommittee on EPR; Notice of Meeting

Science.gov (United States)

2010-01-29

... NUCLEAR REGULATORY COMMISSION Advisory Committee On Reactor Safeguards (ACRS) Meeting of the ACRS Subcommittee on EPR; Notice of Meeting The ACRS U.S. Evolutionary Power Reactor (EPR) Subcommittee will hold a... with Open Items concerning the U.S. EPR Design Certification (DCD) Application and the Calvert Cliffs...

Identification of novel light-induced genes in the suprachiasmatic nucleus

Directory of Open Access Journals (Sweden)

Piontkivska Helen

2007-11-01

Full Text Available Abstract Background The transmission of information about the photic environment to the circadian clock involves a complex array of neurotransmitters, receptors, and second messenger systems. Exposure of an animal to light during the subjective night initiates rapid transcription of a number of immediate-early genes in the suprachiasmatic nucleus of the hypothalamus. Some of these genes have known roles in entraining the circadian clock, while others have unknown functions. Using laser capture microscopy, microarray analysis, and quantitative real-time PCR, we performed a comprehensive screen for changes in gene expression immediately following a 30 minute light pulse in suprachiasmatic nucleus of mice. Results The results of the microarray screen successfully identified previously known light-induced genes as well as several novel genes that may be important in the circadian clock. Newly identified light-induced genes include early growth response 2, proviral integration site 3, growth-arrest and DNA-damage-inducible 45 beta, and TCDD-inducible poly(ADP-ribose polymerase. Comparative analysis of promoter sequences revealed the presence of evolutionarily conserved CRE and associated TATA box elements in most of the light-induced genes, while other core clock genes generally lack this combination of promoter elements. Conclusion The photic signalling cascade in the suprachiasmatic nucleus activates an array of immediate-early genes, most of which have unknown functions in the circadian clock. Detected evolutionary conservation of CRE and TATA box elements in promoters of light-induced genes suggest that the functional role of these elements has likely remained the same over evolutionary time across mammalian orders.

Glucocorticoid-Induced Leucine Zipper Protects the Retina From Light-Induced Retinal Degeneration by Inducing Bcl-xL in Rats.

Science.gov (United States)

Gu, Ruiping; Tang, Wenyi; Lei, Boya; Ding, Xinyi; Jiang, Cheng; Xu, Gezhi

2017-07-01

The aim of the present study was to investigate the neuroprotective effects of glucocorticoid-induced leucine zipper (GILZ) in a light-induced retinal degeneration model and to explore the underlying mechanisms. Intravitreal injection of recombinant GILZ-overexpressing lentivirus (OE-GILZ-rLV) and short hairpin RNA targeting GILZ recombinant lentivirus (shRNA-GILZ-rLV) was performed to up- and downregulate retinal GILZ, respectively. Three days after stable transduction, rats were exposed to continuous bright light (5000 lux) for 2 days. Retinal function was assessed by full-field electroretinography (ERG), and the retinal structure was examined for photoreceptor survival and death in rats kept under a 12-hour light:2-hour dark cycle following light exposure. The expression levels of retinal Bcl-xL, caspase-9, and caspase-3 were examined by Western blotting or real-time PCR at 1, 3, 5, and 7 days after light exposure. Exposure to bright light downregulated retinal GILZ in parallel with the downregulation of Bcl-xL and the upregulation of active caspase-3. Overexpression of retinal GILZ attenuated the decrease of Bcl-xL and the activation of caspase-9 and caspase-3 at 1, 3, 5, and 7 days after bright light exposure, respectively. GILZ silencing aggravated the downregulation of Bcl-xL induced by bright light exposure. Bright light exposure reduced the amplitude of ERG, increased the number of apoptotic photoreceptor cells, and decreased retinal thickness; and GILZ overexpression could attenuate all these effects. Overexpression of GILZ by OE-GILZ-rLV transduction protected the retina from light-induced cellular damage by activating antiapoptotic pathways.

Collinear light scattering using electromagnetically induced transparency

International Nuclear Information System (INIS)

Harris, S.E.; Sokolov, A.V.; Walker, D.R.; Yavuz, D.D.; Yin, G.Y.

2001-01-01

The paper describes two types of nonlinear optical processes which are based on electromagnetically induced transparency. These are: (1) Collinear generation of FM-like Raman sidebands and (2) a type of pondermotive light scattering which is inherent to the interaction of slow light with cold atoms. Connections to other areas of EIT-based nonlinear optics are also described

Nitrogen ligation to manganese in the photosynthetic oxygen-evolving complex: Continuous-wave and pulsed EPR studies of Photosystem II particles containing 14N or 15N

International Nuclear Information System (INIS)

DeRose, V.J.; Yachandra, V.K.; McDermott, A.E.; Britt, R.D.; Sauer, K.; Klein, M.P.

1991-01-01

The possibility of nitrogen ligation to the Mn in the oxygen-evolving complex from photosystem II was investigated with electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectroscopies using 14 N- and 15 N-labeled preparations. Oxygen-evolving preparations were isolated from a thermophilic cyanobacterium, Synechococcus sp., grown on a medium containing either 14 NO 3 - or 15 NO - 3 as the sole source of nitrogen. The substructure on the multiline EPR signal, which arises from Mn in the S 2 state of the enzyme, was measured with continuous-wave EPR. No changes were detected in the substructure peak positions upon substitution of 15 N for 14 N, indicating that this substructure is not due to superhyperfine coupling from nitrogen ligands. To detect potential nitrogen ligands with superhyperfine couplings of lesser magnitude than could be observed with conventional EPR methods, electron spin-echo envelope modulation experiments were also performed on the multiline EPR signal. The Fourier transform of the light-minus-dark time domain ESEEM data shows a peak at 4.8 MHz in 14 N samples which is absent upon substitution with 15 N. This gives unambiguous evidence for weak hyperfine coupling of nitrogen to the Mn of the oxygen-evolving complex. Possible origins of this nitrogen interaction are discussed

Quantum control of light using electromagnetically induced transparency

International Nuclear Information System (INIS)

Andre, A; Eisaman, M D; Walsworth, R L; Zibrov, A S; Lukin, M D

2005-01-01

We present an overview of recent theoretical and experimental work on the control of the propagation and quantum properties of light using electromagnetically induced transparency in atomic ensembles. Specifically, we discuss techniques for the generation and storage of few-photon quantum-mechanical states of light as well as novel approaches to manipulate weak pulses of light via enhanced nonlinear optical processes

EPR Study of Free Radicals in Cotton Fiber for Its Potential Use as a Fortuitous Dosimeter in Radiological Accidents

International Nuclear Information System (INIS)

Sudprasert, W.; Insuan, P.; Khamkhrongmee, S.

2014-01-01

Electron paramagnetic resonance (EPR) spectroscopy was applied to characterize radiation- induced free radicals in cotton fiber in order to determine the possibility for using cotton as a fortuitous dosimeter in accidental exposures to radiation. Cotton fabrics were irradiated at 0.1, 0.5, 1, 2, 10, 50 and 500 Gy using a 60Co gamma source. The irradiated samples were then stored in the dark under controlled environmental conditions for 1, 15, 35 and 60 days. The EPR spectra were observed in samples using a Bruker EMX X-band spectrometer equipped with a TE102 rectangular cavity. The EPR signal intensities of irradiated samples were determined from peak-to-peak amplitudes of EPR spectra and compared to unirradiated samples. The following optimum parameters were used: modulation frequency,100 kHz; microwave frequency, 9.84 GHz; modulation amplitude, 1.8 mT; microwave power,1.0 mW; time constant, 665 ms; conversion time, 41 ms; and sweep time, 41.98 s. The EPR spectra of unirradiated samples show a singlet line with g = 2.006 due to stable organic radicals pre-existing in the cotton fibers, whereas those of irradiated samples show the same pattern with different signal intensities according to the doses. Irradiation increased the signal intensity in a dose dependent manner. The signal intensity exhibited an exponential decay with storage time from 1 to 60 days. Obviously, the degree of fading of EPR intensity did not depend on the absorbed dose from 0.1-50 Gy. The maximum fading was about 60% at 60 days storage of irradiated samples at all doses. However the post-irradiation signal appeared to be detectable up to 60 days after irradiation. The results indicate the potential of using cotton as a fortuitous dosimeter in radiological accidents.

Stability of cellulose radicals produced by radiation in spices as studied by the EPR spectroscopy

International Nuclear Information System (INIS)

Lehner, K.; Stachowicz, W.

2003-01-01

The results are presented of EPR measurements on the stability of cellulose radicals produced in 26 popular spices irradiated with a dose of 7 kGy of gamma rays. EPR measurements were done with the use of an EPR spectrometer EPR-10 MINI at X band (microwave radiation of frequency 9.5 GHz), produced by St. Petersburg Instruments Ltd. The aim of the work was to prove the applicability of the EPR method for the control of irradiation in the investigated spices. (author)

Light-induced aggregation of microbial exopolymeric substances.

Science.gov (United States)

Sun, Luni; Xu, Chen; Zhang, Saijin; Lin, Peng; Schwehr, Kathleen A; Quigg, Antonietta; Chiu, Meng-Hsuen; Chin, Wei-Chun; Santschi, Peter H

2017-08-01

Sunlight can inhibit or disrupt the aggregation process of marine colloids via cleavage of high molecular weight compounds into smaller, less stable fragments. In contrast, some biomolecules, such as proteins excreted from bacteria can form aggregates via cross-linking due to photo-oxidation. To examine whether light-induced aggregation can occur in the marine environment, we conducted irradiation experiments on a well-characterized protein-containing exopolymeric substance (EPS) from the marine bacterium Sagitulla stellata. Our results show that after 1 h sunlight irradiation, the turbidity level of soluble EPS was 60% higher than in the dark control. Flow cytometry also confirmed that more particles of larger sized were formed by sunlight. In addition, we determined a higher mass of aggregates collected on filter in the irradiated samples. This suggests light can induce aggregation of this bacterial EPS. Reactive oxygen species hydroxyl radical and peroxide played critical roles in the photo-oxidation process, and salts assisted the aggregation process. The observation that Sagitulla stellata EPS with relatively high protein content promoted aggregation, was in contrast to the case where no significant differences were found in the aggregation of a non-protein containing phytoplankton EPS between the dark and light conditions. This, together with the evidence that protein-to-carbohydrate ratio of aggregates formed under light condition is significantly higher than that formed under dark condition suggest that proteins are likely the important component for aggregate formation. Light-induced aggregation provides new insights into polymer assembly, marine snow formation, and the fate/transport of organic carbon and nitrogen in the ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrogen Analyses in the EPR

International Nuclear Information System (INIS)

Worapittayaporn, S.; Eyink, J.; Movahed, M.

2008-01-01

In severe accidents with core melting large amounts of hydrogen may be released into the containment. The EPR provides a combustible gas control system to prevent hydrogen combustion modes with the potential to challenge the containment integrity due to excessive pressure and temperature loads. This paper outlines the approach for the verification of the effectiveness and efficiency of this system. Specifically, the justification is a multi-step approach. It involves the deployment of integral codes, lumped parameter containment codes and CFD codes and the use of the sigma criterion, which provides the link to the broad experimental data base for flame acceleration (FA) and deflagration to detonation transition (DDT). The procedure is illustrated with an example. The performed analyses show that hydrogen combustion at any time does not lead to pressure or temperature loads that threaten the containment integrity of the EPR. (authors)

Development of a new dosimeter of EPR based on lactose; Desarrollo de un nuevo dosimetro de RPE basado en lactosa

Energy Technology Data Exchange (ETDEWEB)

Cruz C, L.; Torijano C, E.; Azorin N, J.; Aguirre G, F. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Cruz Z, E., E-mail: eftc@xanum.uam.mx [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2014-08-15

50 years have passed since was proposed using the amino acid alanine as dosimeter advantage the phenomenon of electron paramagnetic resonance (EPR); this dosimetric method has reached a highly competitive level regarding others dosimetry classic methods, for example the thermoluminescence or the use of Fricke dosimeters, to measure high dose of radiation. In this type of materials, the free radicals induced by the radiation are stable and their concentration is proportional to the absorbed dose may be determined by the amplitude pick to pick of the first derived of the EPR absorption spectrum. The obtained results studying the EPR response of lactose tablets elaborated in the Universidad Autonoma Metropolitana, Unidad Iztapalapa are presented. The tablets were irradiated with gamma radiation of {sup 60}Co in the irradiator Gamma beam 651-Pt of the Instituto de Ciencias Nucleares de la Universidad Nacional Autonoma de Mexico to a dose rate of 8 kGy-h{sup -1} and their EPR response in a EPR spectrometer e-scan Bruker. The obtained response in function of the dose was lineal in the interval of 1 at 10 kGy. The lactose sensibility was compared with the l-alanine, used as reference, and the result was consistently 0.25 of this. Due to the linearity shown in the interval of used dose and their low production cost, we conclude that the lactose is a promissory option for the dosimetry of high dose of radiation. (author)

Study of growth of polyaniline chain by EPR method

Energy Technology Data Exchange (ETDEWEB)

Kulikov, A V [Inst. of Chemical Physics, Chernogolovka (Russian Federation); Kogan, Ya L [Inst. of Chemical Physics, Chernogolovka (Russian Federation); Fokeeva, L S [Inst. of Chemical Physics, Chernogolovka (Russian Federation)

1993-03-22

Chemical aniline polymerization has been studied by the EPR method. After a long delay a weak EPR signal I is appeared and transformed rapidly into a strong Lorentzian line. Constants of spin exchange of signals I and II with paramagnetic probes Fe(CN)[sub 6][sup 3-], Co[sup 2+] and O[sub 2], freely diffusing in solution, have been determined. Effect of ferricyanide ions and urea, a breaker of hydrogen bonds, has been measured for signals I and II. Data obtained show the formation of an array of positive charges in PANI at early stage of doping. Constants of spin exchange depend on prehistory of samples. Averaging of EPR line widths of different paramagnetic centers in polyaniline was found. (orig.)

EPR Flamanville 3, Site Management

International Nuclear Information System (INIS)

Menager, Antoine

2014-01-01

Antoine Menager, the EPR Flamanville 3 Site Manager described the organization and the management of the Flamanville site during the construction phase. He placed emphasis on Health and Safety, Environmental and Social Responsibility and on Nuclear Safety and Quality

EPR structure of the gamma irradiated alanine spectrum

Energy Technology Data Exchange (ETDEWEB)

Cabral P, A; Jimenez D, H; Urena N, F; Galindo, S; Bosch, P

1992-03-15

In this study is shown that the broadened five-line EPR pattern of the gamma irradiated alanine possibly decomposes into a more complex pattern when the recorded spectrum is subject to an operation of deconvolution. The EPR powder spectra of gamma irradiated DL- and L-alanine with and without binders are analysed. In all recorded spectra, each observed line is resolved into an asymmetrical triplet when a Gaussian distribution of 8.2 gauss width is removed, by deconvolution, from the observed spectrum. On the other hand, from a simple fitting analysis carried out on the original data, one encounters that some calculated relations between characteristic parameters, such as intensity ratios, deviate consistently from assumed height ratios. Both, from deconvolution and fitting results, a different structure is suggested for the observed broadened five-line EPR pattern of {gamma}-irradiated powder DL- and L-alanine. (Author)

Free radical EPR in delineating oil bearing zones

International Nuclear Information System (INIS)

Sharma, R.K.; Kumar, V.; Das, T.K.; Gundu Rao, T.K.

1993-01-01

Presence of naturally occurring gamma ray activity has long been detected in oil/gas wells is invariably carried out for formation evaluation. Similarly, presence of free radicals in oil bearing formations has also been known for quite sometime. Present paper deals with a systematic study of detecting these free radicals in oil wells and correlations of these with x-ray and other logs for identification of hydrocarbon bearing zones. Present study attempts to establish EPR as as inexpensive and reliable tool in comparison with gamma ray and neutron density logs recorded in exploratory oil wells. EPR studies have been carried out in an exploratory well between depth intervals 1600 m-1400 m located in south of existing producing field in Bombay Offshore region. Based on these results, an EPR log has been prepared and compared with gamma ray and neutron density logs. (author). 4 refs., 1 fig., 1 tab

EPR structure of the gamma irradiated alanine spectrum

International Nuclear Information System (INIS)

Cabral P, A.; Jimenez D, H.; Urena N, F.; Galindo, S.; Bosch, P.

1992-03-01

In this study is shown that the broadened five-line EPR pattern of the gamma irradiated alanine possibly decomposes into a more complex pattern when the recorded spectrum is subject to an operation of deconvolution. The EPR powder spectra of gamma irradiated DL- and L-alanine with and without binders are analysed. In all recorded spectra, each observed line is resolved into an asymmetrical triplet when a Gaussian distribution of 8.2 gauss width is removed, by deconvolution, from the observed spectrum. On the other hand, from a simple fitting analysis carried out on the original data, one encounters that some calculated relations between characteristic parameters, such as intensity ratios, deviate consistently from assumed height ratios. Both, from deconvolution and fitting results, a different structure is suggested for the observed broadened five-line EPR pattern of γ-irradiated powder DL- and L-alanine. (Author)

Public debate about the EPR nuclear power plant at Flamanville; Debat public sur la centrale nucleaire EPR a Flamanville

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

The project of building of he EPR reactor at Flamanville (Manche, France) has been submitted to the public debate. This document includes a presentation of the project and of the rules of the public debate, a synthesis of the file made by the prime contractor (EDF), a synthesis of the collective book of national actors concerned by the project (a group of associations for environment protection, Areva company, the ministries of economy and ecology, Global Chance, association of pro-nuclear ecologists (AEPN), 'Sortir du Nucleaire' (out-of nuclear) network, group of scientists for the information about nuclear (GSIEN), association for the promotion of the Flamanville site (Proflam), French nuclear energy society (SFEN) in association with 'Sauvons le Climat' (let's save climate), regional collective association 'EPR non merci, ni ailleurs, ni ici' (EPR, no thanks, neither elsewhere, nor here), NegaWatt), and 5 detailed books of actors: ACRO (association for the control of radioactivity in Western France), CFDT and CGT syndicates, the economic and social council of Basse Normandie region, and Proflam. (J.S.)

Public debate about the EPR nuclear power plant at Flamanville; Debat public sur la centrale nucleaire EPR a Flamanville

Energy Technology Data Exchange (ETDEWEB)

NONE

2005-07-01

The project of building of he EPR reactor at Flamanville (Manche, France) has been submitted to the public debate. This document includes a presentation of the project and of the rules of the public debate, a synthesis of the file made by the prime contractor (EDF), a synthesis of the collective book of national actors concerned by the project (a group of associations for environment protection, Areva company, the ministries of economy and ecology, Global Chance, association of pro-nuclear ecologists (AEPN), 'Sortir du Nucleaire' (out-of nuclear) network, group of scientists for the information about nuclear (GSIEN), association for the promotion of the Flamanville site (Proflam), French nuclear energy society (SFEN) in association with 'Sauvons le Climat' (let's save climate), regional collective association 'EPR non merci, ni ailleurs, ni ici' (EPR, no thanks, neither elsewhere, nor here), NegaWatt), and 5 detailed books of actors: ACRO (association for the control of radioactivity in Western France), CFDT and CGT syndicates, the economic and social council of Basse Normandie region, and Proflam. (J.S.)

EPR: the nuclear impasse

International Nuclear Information System (INIS)

Marillier, F.

2008-01-01

The questions relative to the climatic change constitute crucial challenges for the next ten years. In this context the author aims to show how the EPR project illustrates the nuclear french ''autism''. He presents and analyzes the international and environmental impacts of this obsolete technology, as a project useless and dangerous. (A.L.B.)

EPR of VHal centres in SrS

International Nuclear Information System (INIS)

Seeman, V.; Danilkin, M.; Must, M.; Ots, A.; Paernoja, E.; Pung, L.; Tarkpea, K.

2006-01-01

V Hal centres were studied by EPR in SrS doped with halogens after X-raying the samples at 77 K. V Hal centre arises when a hole is captured by sulphide-ion next to a cation vacancy with a halogen ion substituting the opposite sulphide-ion. EPR parameters and thermal decay characteristics are measured for V Cl , V Br , and V I centres. The efficiency of different halogens to produce and stabilise cation vacancies is shown to vary for different alkaline earth sulphides. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Copper ESEEM and HYSCORE through ultra-wideband chirp EPR spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Segawa, Takuya F.; Doll, Andrin; Pribitzer, Stephan; Jeschke, Gunnar, E-mail: gjeschke@ethz.ch [ETH Zurich, Laboratory of Physical Chemistry, Vladimir-Prelog-Weg 2, CH-8093 Zurich (Switzerland)

2015-07-28

The main limitation of pulse electron paramagnetic resonance (EPR) spectroscopy is its narrow excitation bandwidth. Ultra-wideband (UWB) excitation with frequency-swept chirp pulses over several hundreds of megahertz overcomes this drawback. This allows to excite electron spin echo envelope modulation (ESEEM) from paramagnetic copper centers in crystals, whereas up to now, only ESEEM of ligand nuclei like protons or nitrogens at lower frequencies could be detected. ESEEM spectra are recorded as two-dimensional correlation experiments, since the full digitization of the electron spin echo provides an additional Fourier transform EPR dimension. Thus, UWB hyperfine-sublevel correlation experiments generate a novel three-dimensional EPR-correlated nuclear modulation spectrum.

High-field EPR on membrane proteins - crossing the gap to NMR.

Science.gov (United States)

Möbius, Klaus; Lubitz, Wolfgang; Savitsky, Anton

2013-11-01

In this review on advanced EPR spectroscopy, which addresses both the EPR and NMR communities, considerable emphasis is put on delineating the complementarity of NMR and EPR concerning the measurement of molecular interactions in large biomolecules. From these interactions, detailed information can be revealed on structure and dynamics of macromolecules embedded in solution- or solid-state environments. New developments in pulsed microwave and sweepable cryomagnet technology as well as ultrafast electronics for signal data handling and processing have pushed to new horizons the limits of EPR spectroscopy and its multifrequency extensions concerning the sensitivity of detection, the selectivity with respect to interactions, and the resolution in frequency and time domains. One of the most important advances has been the extension of EPR to high magnetic fields and microwave frequencies, very much in analogy to what happens in NMR. This is exemplified by referring to ongoing efforts for signal enhancement in both NMR and EPR double-resonance techniques by exploiting dynamic nuclear or electron spin polarization via unpaired electron spins and their electron-nuclear or electron-electron interactions. Signal and resolution enhancements are particularly spectacular for double-resonance techniques such as ENDOR and PELDOR at high magnetic fields. They provide greatly improved orientational selection for disordered samples that approaches single-crystal resolution at canonical g-tensor orientations - even for molecules with small g-anisotropies. Exchange of experience between the EPR and NMR communities allows for handling polarization and resolution improvement strategies in an optimal manner. Consequently, a dramatic improvement of EPR detection sensitivity could be achieved, even for short-lived paramagnetic reaction intermediates. Unique structural and dynamic information is thus revealed that can hardly be obtained by any other analytical techniques. Micromolar

EPR in characterization of seeds paramagnetic species

International Nuclear Information System (INIS)

Luiz, A.P.C.; Mauro, M.F.F.L.; Portugal, K.O.; Barbana, V.M.; Guedes, C.L.B.; Mauro, E. di; Carneiro, C.E.A.; Zaia, D.A.M.; Prete, C.E.C.

2011-01-01

Full text. In Brazil, since 1970s, renewable fuel programs has been developed in order to replace petroleum. Today a program that has been discussed is the bio diesel, which intend to replace diesel fuel, fossil oil, to bio diesel, renewal fuel. As seeds are the basis for production of oil and consequently processed into bio diesel, the goal of this work is to characterize and compare paramagnetic species present in the seeds by Electron Paramagnetic Resonance (EPR). Samples used in this study were seeds of sorghum, barley, corn, peanuts, soy beans, cotton, wheat, oats, mustard, rice, sunflower and turnip. Some paramagnetic species present in soil was also investigated as goethite (FeOOH), hematite (Fe 2 O 3 ), magnetite (Fe 3 O 4 ), and ferrihydrite (Fe 5 HO 8 · 4H 2 O), since, these species present in appreciable quantities in the soil can be present in the seeds and analyzed for comparison. The characterization of these species is essential to understand the EPR seeds spectra. Each sample is placed in a thin quartz tube 4 mm in diameter, and it is inserted into the cavity of the spectrometer at room temperature, at low temperature (77 K) and variable temperature using liquid nitrogen flow and hot flow through a compressor air. It was used as standard Mg O:Mn 2+ , which is also inserted into the cavity. Shortly after the potency is regulated, frequency, amplitude and sweep the field. The spectroscopic analysis by EPR X-band (∼ 9:5GHz), were performed at the Fluorescence and Electron Paramagnetic Resonance Laboratory, Exact Sciences Center, State University of Londrina, Parana state, Brazil, through an EPR spectrometer JEOL brand (JES-PE-3X). In the EPR spectra, spectroscopic factor or g factor and line width were determined in paramagnetic species. Studies from several seeds with EPR technique detected in all of them presence of same complex of Fe 3+ present in the goethite at g ∼ 2, and in the seeds exist free radicals at g = 2:004, at room temperature

EPR in characterization of seeds paramagnetic species

Energy Technology Data Exchange (ETDEWEB)

Luiz, A.P.C.; Mauro, M.F.F.L.; Portugal, K.O.; Barbana, V.M.; Guedes, C.L.B.; Mauro, E. di; Carneiro, C.E.A.; Zaia, D.A.M.; Prete, C.E.C. [Universidade Estadual de Londrina (UEL), PR (Brazil)

2011-07-01

Full text. In Brazil, since 1970s, renewable fuel programs has been developed in order to replace petroleum. Today a program that has been discussed is the bio diesel, which intend to replace diesel fuel, fossil oil, to bio diesel, renewal fuel. As seeds are the basis for production of oil and consequently processed into bio diesel, the goal of this work is to characterize and compare paramagnetic species present in the seeds by Electron Paramagnetic Resonance (EPR). Samples used in this study were seeds of sorghum, barley, corn, peanuts, soy beans, cotton, wheat, oats, mustard, rice, sunflower and turnip. Some paramagnetic species present in soil was also investigated as goethite (FeOOH), hematite (Fe{sub 2}O{sub 3}), magnetite (Fe{sub 3}O{sub 4}), and ferrihydrite (Fe{sub 5}HO{sub 8} {center_dot} 4H{sub 2}O), since, these species present in appreciable quantities in the soil can be present in the seeds and analyzed for comparison. The characterization of these species is essential to understand the EPR seeds spectra. Each sample is placed in a thin quartz tube 4 mm in diameter, and it is inserted into the cavity of the spectrometer at room temperature, at low temperature (77 K) and variable temperature using liquid nitrogen flow and hot flow through a compressor air. It was used as standard Mg O:Mn{sup 2+}, which is also inserted into the cavity. Shortly after the potency is regulated, frequency, amplitude and sweep the field. The spectroscopic analysis by EPR X-band ({approx} 9:5GHz), were performed at the Fluorescence and Electron Paramagnetic Resonance Laboratory, Exact Sciences Center, State University of Londrina, Parana state, Brazil, through an EPR spectrometer JEOL brand (JES-PE-3X). In the EPR spectra, spectroscopic factor or g factor and line width were determined in paramagnetic species. Studies from several seeds with EPR technique detected in all of them presence of same complex of Fe{sup 3+} present in the goethite at g {approx} 2, and in the seeds

Specific public debate on the EPR - Position of 'Sauvons le Climat'

International Nuclear Information System (INIS)

2008-01-01

After having evoked the respective performance of Denmark, Sweden and France in terms of CO 2 emission reduction, electricity consumption per inhabitant, and outlined the unavoidable measures of energy saving and reasonable development of renewable energies while keeping on using nuclear energy, this report more particularly addresses various issues related to the EPR within the perspectives of energy production needs. It also outlines the need to stop the current rate of increase of energy consumption, for resource concerns as well as for CO 2 emission concerns, when renewable energies will remain limited. It discusses the objectives of reduction of greenhouse emissions and states that the EPR could be a determining factor to reach these objectives. Moreover, the EPR technology is an industrial asset for France even in front of the emergence of reactors of fourth generation (high temperature gas reactors, fast breeder reactors). It outlines that the EPR design improves nuclear safety and reduces accident probability. Direct, indirect and external costs of the EPR are discussed. The role of this reactor as a tool for electric power production is finally discussed within the French context and within the European context

Estimation of mean and median pO2 values for a composite EPR spectrum.

Science.gov (United States)

Ahmad, Rizwan; Vikram, Deepti S; Potter, Lee C; Kuppusamy, Periannan

2008-06-01

Electron paramagnetic resonance (EPR)-based oximetry is capable of quantifying oxygen content in samples. However, for a heterogeneous environment with multiple pO2 values, peak-to-peak linewidth of the composite EPR lineshape does not provide a reliable estimate of the overall pO2 in the sample. The estimate, depending on the heterogeneity, can be severely biased towards narrow components. To address this issue, we suggest a postprocessing method to recover the linewidth histogram which can be used in estimating meaningful parameters, such as the mean and median pO2 values. This information, although not as comprehensive as obtained by EPR spectral-spatial imaging, goes beyond what can be generally achieved with conventional EPR spectroscopy. Substantially shorter acquisition times, in comparison to EPR imaging, may prompt its use in clinically relevant models. For validation, simulation and EPR experiment data are presented.

Meeting the next generation PWR safety requirements: The EPR Reactor

International Nuclear Information System (INIS)

Salhi, Othman

2008-01-01

The development process pursued the harmonization of technical solutions and the integration of all the lessons learned from earlier nuclear plants built by both vendors. As far as safety more specifically is concerned, the basic choice for the EPR was to adopt an evolutionary approach based on experience feedback from the reactors built by Areva, which at the time already amounted to nearly 100. This philosophy makes today's Areva EPR the natural descendant of the most advanced French N4 and German Konvoi power reactors currently in operation. EPR design choices affecting safety were motivated by a continuous quest for higher levels of safety. A two-fold approach was followed: 1. improvement of the measures aimed at further reducing the already very low probability of core melt 2. incorporation of measures aimed at further limiting the consequences of a severe accident, in the knowledge that its probability of occurrence has been considerably reduced. Through its filiations with French N4 and German Konvoi power reactors, the EPR benefits from the uninterrupted, evolutionary innovation process that has supported the development of PWRs since their introduction into the market place. This is especially true for safety where the EPR brings a unique combination of both tried and tested and innovative features that further improve the prevention of severe accidents and their mitigation

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique

Science.gov (United States)

Rakvin, B.; Carić, D.; Kveder, M.

2018-02-01

The microwave magnetic field strength, B1, in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ωrf, which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B1, decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed.

Enhanced accuracy of the microwave field strength measurement in a CW-EPR by pulsed modulation technique.

Science.gov (United States)

Rakvin, B; Carić, D; Kveder, M

2018-02-01

The microwave magnetic field strength, B 1 , in the cavity of a conventional continuous wave electron paramagnetic resonance, CW-EPR, spectrometer was measured by employing modulation sidebands, MS, in the EPR spectrum. MS spectrum in CW-EPR is produced by applying the modulation frequency, ω rf , which exceeds the linewidth, δB, given in frequency units. An amplitude-modulated CW-EPR, AM-CW-EPR, was selected as detection method. Theoretical description of AM-CW-EPR spectrum was modified by adding Bloch-Siegert-like shift obtained by taking into account the cumulative effect of the non-resonant interactions between the driving fields and the spin system. This approach enables to enhance the precision of B 1 measurement. In order to increase the sensitivity of the method when saturation effects, due to higher intensity of B 1 , decrease the resolution of AM-CW-EPR spectrum, detection at the second harmonic of CW-EPR has been employed. Copyright © 2018 Elsevier Inc. All rights reserved.

EPR investigation of some desiccated Ascomycota and Basidiomycota gamma-irradiated mushrooms

Energy Technology Data Exchange (ETDEWEB)

Bercu, V., E-mail: vbercu@gmail.co [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania); Negut, C.D., E-mail: dnegut@nipne.r [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania); Horia Hulubei National Institute for Physics and Nuclear Engineering, P.O. Box MG-6, 077125 Magurele (Ilfov) (Romania); Duliu, O.G., E-mail: duliu@b.astral.r [University of Bucharest, Department of Atomic and Nuclear Physics, P.O. Box MG-11, 077125 Magurele (Ilfov) (Romania)

2010-12-15

The suitability of the EPR spectroscopy for detection of {gamma}-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel-Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom-Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle-Cantharellus cibarius Fr., as well as oyster mushroom-Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.

EPR investigation of some desiccated Ascomycota and Basidiomycota gamma-irradiated mushrooms

Science.gov (United States)

Bercu, V.; Negut, C. D.; Duliu, O. G.

2010-12-01

The suitability of the EPR spectroscopy for detection of γ-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel— Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom— Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle— Cantharellus cibarius Fr., as well as oyster mushroom— Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.

EPR investigation of some desiccated Ascomycota and Basidiomycota gamma-irradiated mushrooms

International Nuclear Information System (INIS)

Bercu, V.; Negut, C.D.; Duliu, O.G.

2010-01-01

The suitability of the EPR spectroscopy for detection of γ-irradiation in five species of dried mushroom, currently used in gastronomy: yellow morel-Morchella esculenta, (L.) Pers. (Phylum Ascomycota), button mushroom-Agaricus bisporus (J.E.Lange), Agaricus haemorrhoidarius Fr., golden chantarelle-Cantharellus cibarius Fr., as well as oyster mushroom-Pleurotus ostreatus (Jacq. ex Fr.) (Phylum Basidiomycota) is presented and discussed. Although after irradiation at doses up to 11 kGy, all specimens presented well defined EPR spectra, only A. bisporus EPR signal was enough stable to make detection possible after 18 months.

Recent progress in synchrotron-based frequency-domain Fourier-transform THz-EPR.

Science.gov (United States)

Nehrkorn, Joscha; Holldack, Karsten; Bittl, Robert; Schnegg, Alexander

2017-07-01

We describe frequency-domain Fourier-transform THz-EPR as a method to assign spin-coupling parameters of high-spin (S>1/2) systems with very large zero-field splittings. The instrumental foundations of synchrotron-based FD-FT THz-EPR are presented, alongside with a discussion of frequency-domain EPR simulation routines. The capabilities of this approach is demonstrated for selected mono- and multinuclear HS systems. Finally, we discuss remaining challenges and give an outlook on the future prospects of the technique. Copyright © 2017 Elsevier Inc. All rights reserved.

On the Correlation between EPR and Positron Annihilation Measurements on gamma-Irradiated Acetyl Methionine

DEFF Research Database (Denmark)

Eldrup, Morten Mostgaard; Lund-Thomsen, E.; Mogensen, O. E.

1972-01-01

The dose dependence of the relative EPR signal intensity and positron lifetime spectrum was measured for γ‐irradiated acetyl methionine in the dose range from 0 to 30 Mrad. Angular correlation measurements were performed for the doses 0 and 30 Mrad. The result of the irradiation was the creation...... of EPR centers and inhibition of positronium formation. For one sample, irradiated with a dose of 30 Mrad, EPR and positron lifetime spectra were followed over a period of 50 days after the irradiation. The inhibiting effect and the EPR signal intensity decreased with time. No simple correlation could...... be established between the number of EPR centers and the positron annihilation data, but other possible explanations are discussed....

Signal processing for radiation dosimetry using EPR in dental enamel: comparison of three methods

International Nuclear Information System (INIS)

Pass, B. Barry.; Shames, A.I. Alexander I.

2000-01-01

We are reporting an alternative method of extracting useful dose information from complex EPR spectra of dental enamel. Digital differentiation of the initial first derivative spectrum followed by filtering is used to clearly distinguish the radiation-induced signal from the native background signal. The peak-to-peak height of the resulting second derivative of the signal is then measured as an indication of absorbed dose. This method does not require preliminary elimination of the native background signal, and is not effected by any uncertainty in the determination of the background signal or by errors resulting from the subtraction of two signals of comparable magnitude. Ten enamel samples were irradiated with known doses in the range of 250-10 5 mGy. There was agreement for all the samples, within the typical experimental error of ±10% for EPR dosimetry in dental enamel, between the doses determined by two common techniques using native signal subtraction and the doses determined by the new second derivative method proposed here

EPR of gamma-irradiated polycrystalline alanine-in-glass dosimeter

International Nuclear Information System (INIS)

Al-Karmi, Anan M.; Morsy, M.A.

2008-01-01

This study attempts to overcome some of the reported discrepancies in alanine-EPR reproducibility that may be related to alanine dosimeter preparation and/or EPR spectrometer settings. The dosimeters were prepared by packing pure polycrystalline L-α-alanine directly as supplied by the manufacturer in glass tubes. This dosimeter production scheme avoids any possible contribution to the EPR signal from a binding material. The dosimeters were irradiated with gamma ray to low-dose ranges typical for medical therapy (0-20 Gy). Special attention has been paid to the study of minimum detectable dose, measurement repeatability and reproducibility, and post-irradiation stability. The dosimeter exhibited a linear dose response in the dose range from 0.1 to 20 Gy. These positive properties favor the polycrystalline alanine-in-glass tube as a radiation dosimeter

Effect of the shape and size of dosimeters on the response of solid state/EPR dosimetry

International Nuclear Information System (INIS)

Yordanov, Nicola D.; Fabisiak, Slawomir; Lagunov, Oleg

2006-01-01

The influence of the shape and size of dosimeters used in solid state-EPR (SS/EPR) dosimetry on their response is reported. It is shown that for commonly used cylindrical (rod) shaped dosimeters of equal height, prepared of low (ε=<3) dielectric constant materials, linearity between their volume and the EPR response is observed when their diameter varies between 3 and 5mm. Further increase of the dosimeter's diameter is not recommended since the increased penetration of the dosimeter material into the electric component of the microwave field in the EPR cavity increases the dielectric losses and decreases the EPR response. In an attempt to improve the sensitivity of the SS/EPR dosimetry we have prepared and tested new, flat-shaped, dosimeters of low (ε∼2) dielectric constant materials which were found to exhibit: (i) linear EPR response within 1-5mm thickness; (ii) higher sensitivity than cylindrical dosimeters at equal sample volume; (iii) increased by ca. 270% EPR sensitivity at 5mm thickness compared to the cylindrical dosimeters with the same diameter (ca. 1.7 times increased sample volume). Using flat shape dosimeters of suitable size provides 2.7 times higher EPR sensitivity of single estimation

EPR project construction cost control

International Nuclear Information System (INIS)

Duflo, D.; Pouget-Abadie, X.; Dufour, A.; Kauffmann, G.

2001-01-01

The EPR project is now managed by EDF in cooperation with the German Utilities. The main engineering activities for this period are related to the preparation of construction project management, deepening of some safety issues, definition of the project technical reference. The EPR project concerns the so-called reference unit, that is an isolated first-off unit, with unit electrical power of about 1500 MW. The construction costs evaluated are those of the nuclear island, the conventional island, site facilities, installation work and the administrative buildings. The EPR project construction cost evaluation method applies to all the equipment installed and commissioned. It requires the availability of a preliminary project detailed enough to identify the bill of quantities. To these quantities are then assigned updated unit prices that are based either on cost bases for similar and recent facilities or taken from request for quotation for similar equipment or result from gains due to contractual conditions benefiting from simplifications in the functional and technical specifications. The input and output data are managed in a model that respects the breakdown on which the evaluation method is based. The structural organization of this method reflects a functional breakdown on the one hand (nuclear island, conventional island, common site elements) and on the other hand a breakdown according to equipment or activity (civil engineering, mechanics, electricity, instrumentation and control). This paper discusses the principle and the method of construction cost evaluation carried out, the cost data base and input and output parameters as well as results and oncoming cost analysis tasks. (author)

On Aerts' overlooked solution to the EPR paradox

OpenAIRE

de Bianchi, Massimiliano Sassoli

2018-01-01

The Einstein-Podolsky-Rosen (EPR) paradox was enunciated in 1935 and since then it has made a lot of ink flow. Being a subtle result, it has also been largely misunderstood. Indeed, if questioned about its solution, many physicists will still affirm today that the paradox has been solved by the Bell-test experimental results, which have shown that entangled states are real. However, this remains a wrong view, as the validity of the EPR ex-absurdum reasoning is independent from the Bell-test e...

EPR of defects in semiconductors: past, present, future

International Nuclear Information System (INIS)

Watkins, G.D.

1999-01-01

Important physical concepts learned from early EPR studies of defects in silicon are reviewed. Highlighted are the studies of shallow effective-mass-liked donors and acceptors of deep transition element impurities, and of vacancies and interstitials. It is shown that the concepts learned in silicon translate remarkable well to the corresponding defects in the other elemental and compound semiconductors. The introduction of sensitive optical and electrical detection methods and the recent progress in single defects detection insure the continued vital role of EPR in the future

Alanine-EPR dosimetry system for high industrial as well radiotherapeutic dose measurement

International Nuclear Information System (INIS)

Dobrovodsky, J.; Bukovjan, J.

2005-01-01

Slovak Institute of Metrology is developing new metrology standard for high doses, based on the alanine-EPR as a reference dosimetry system. A Bruker e-scan EPR analyser developed specifically for alanine dosimetry has improved stability of EPR measurement, especially at lower dose range. The standard e-scan system provides sensitivity below 1 Gray. After further improvement of the system and lowering of dose determination expanded uncertainty down below 1 %, its utilisation for radiotherapy field is expected (authors)

Antioxidant Capacity: Experimental Determination by EPR Spectroscopy and Mathematical Modeling.

Science.gov (United States)

Polak, Justyna; Bartoszek, Mariola; Chorążewski, Mirosław

2015-07-22

A new method of determining antioxidant capacity based on a mathematical model is presented in this paper. The model was fitted to 1000 data points of electron paramagnetic resonance (EPR) spectroscopy measurements of various food product samples such as tea, wine, juice, and herbs with Trolox equivalent antioxidant capacity (TEAC) values from 20 to 2000 μmol TE/100 mL. The proposed mathematical equation allows for a determination of TEAC of food products based on a single EPR spectroscopy measurement. The model was tested on the basis of 80 EPR spectroscopy measurements of herbs, tea, coffee, and juice samples. The proposed model works for both strong and weak antioxidants (TEAC values from 21 to 2347 μmol TE/100 mL). The determination coefficient between TEAC values obtained experimentally and TEAC values calculated with proposed mathematical equation was found to be R(2) = 0.98. Therefore, the proposed new method of TEAC determination based on a mathematical model is a good alternative to the standard EPR method due to its being fast, accurate, inexpensive, and simple to perform.

Application of EPR retrospective dosimetry for large-scale accidental situation

International Nuclear Information System (INIS)

Skvortsov, V.G.; Ivannikov, A.I.; Stepanenko, V.F.; Tsyb, A.F.; Khamidova, L.G.; Kondrashov, A.E.; Tikunov, D.D.

2000-01-01

Above 3000 tooth enamel samples, collected at population of radioactive contaminated territories after Chernobyl accident, the Chernobyl liquidators, the retired military of high radiation risk and the population of control radiation free territories were investigated by EPR spectroscopy method in order to obtain accumulated individual exposure doses. Results of EPR spectra measurements are stored in data bank; enamel samples are also stored in order to provide the possibility to repeat the measurements in future. Statistical analysis of results has allowed to detect the contribution into EPR signal in tooth enamel due to the action of the natural background radiation, and the radioactive contamination of territory. In general, the average doses of external exposure of the population obtained with EPR spectroscopy of teeth enamel are consistent with results based on other methods of direct and retrospective dosimetry. Essential exceeding of the individual doses above the average level within the population groups was observed for some persons. That gave the possibility to detect the individuals with overexposure, which were included into groups for medical monitoring

New loophole for the EPR paradox

OpenAIRE

Feldmann, Michel

1999-01-01

We exhibit a classical model free from any paradox which exactly simulates the spin EPR test. We conclude that Bell's inequality violation is a strictly classical phenomenon, contrary to a general belief.

EPR investigations of silicon carbide nanoparticles functionalized by acid doped polyaniline

Science.gov (United States)

Karray, Fekri; Kassiba, Abdelhadi

2012-06-01

Nanocomposites (SiC-PANI) based on silicon carbide nanoparticles (SiC) encapsulated in conducting polyaniline (PANI) are synthesized by direct polymerization of PANI on the nanoparticle surfaces. The conductivity of PANI and the nanocomposites was modulated by several doping levels of camphor sulfonic acid (CSA). Electron paramagnetic resonance (EPR) investigations were carried out on representative SiC-PANI samples over the temperature range [100-300 K]. The features of the EPR spectra were analyzed taking into account the paramagnetic species such as polarons with spin S=1/2 involved in two main environments realized in the composites as well as their thermal activation. A critical temperature range 200-225 K was revealed through crossover changes in the thermal behavior of the EPR spectral parameters. Insights on the electronic transport properties and their thermal evolutions were inferred from polarons species probed by EPR and the electrical conductivity in doped nanocomposites.

EPR investigations of silicon carbide nanoparticles functionalized by acid doped polyaniline

Energy Technology Data Exchange (ETDEWEB)

Karray, Fekri [Laboratoire des materiaux Ceramiques Composites et Polymeres, Faculte des Sciences de Sfax, BP 802, 3018 Sfax (Tunisia); Kassiba, Abdelhadi, E-mail: kassiba@univ-lemans.fr [Institute of Molecules and Materials of Le Mans (I3M), UMR-CNRS 6283, Universite du Maine, 72085 Le Mans (France)

2012-06-15

Nanocomposites (SiC-PANI) based on silicon carbide nanoparticles (SiC) encapsulated in conducting polyaniline (PANI) are synthesized by direct polymerization of PANI on the nanoparticle surfaces. The conductivity of PANI and the nanocomposites was modulated by several doping levels of camphor sulfonic acid (CSA). Electron paramagnetic resonance (EPR) investigations were carried out on representative SiC-PANI samples over the temperature range [100-300 K]. The features of the EPR spectra were analyzed taking into account the paramagnetic species such as polarons with spin S=1/2 involved in two main environments realized in the composites as well as their thermal activation. A critical temperature range 200-225 K was revealed through crossover changes in the thermal behavior of the EPR spectral parameters. Insights on the electronic transport properties and their thermal evolutions were inferred from polarons species probed by EPR and the electrical conductivity in doped nanocomposites.

The Third International Intercomparison on EPR Tooth Dosimetry: Part 2, final analysis

International Nuclear Information System (INIS)

Wieser, A.; Debuyst, R.; Fattibene, P.; Meghzifene, A.; Onori, S.; Bayankin, S. N.; Brik, A.; Bugay, A.; Chumak, V.; Ciesielski, B.; Hoshi, M.; Imata, H.; Ivannikov, A.; Ivanov, D.; Junczewska, M.; Miyazawa, C.; Penkowski, M.; Pivovarov, S.; Romanyukha, A.; Romanyukha, L.; Schauer, D.; Scherbina, O.; Schultka, K.; Sholom, S.; Skvortsov, V.; Stepanenko, V.; Thomas, J. A.; Tielewuhan, E.; Toyoda, S.; Trompier, F.

2006-01-01

The objective of the Third International Intercomparison on EPR Tooth Dosimetry was to evaluate laboratories performing tooth enamel dosimetry <300 mGy. Final analysis of results included a correlation analysis between features of laboratory dose reconstruction protocols and dosimetry performance. Applicability of electron paramagnetic resonance (EPR) tooth dosimetry at low dose was shown at two applied dose levels of 79 and 176 mGy. Most (9 of 12) laboratories reported the dose to be within 50 mGy of the delivered dose of 79 mGy, and 10 of 12 laboratories reported the dose to be within 100 mGy of the delivered dose of 176 mGy. At the high-dose tested (704 mGy) agreement within 25% of the delivered dose was found in 10 laboratories. Features of EPR dose reconstruction protocols that affect dosimetry performance were found to be magnetic field modulation amplitude in EPR spectrum recording, EPR signal model in spectrum deconvolution and duration of latency period for tooth enamel samples after preparation. (authors)

Error in assessing the absorbed dose from the EPR signal from dental enamel

International Nuclear Information System (INIS)

Kleshchenko, E.D.; Kushnereva, K.K.

1997-01-01

Dose measurements from EPR signals from dental enamel were analyzed in a random sampling of 100 teeth extracted in liquidators of the Chernobyl accident aftermath and the EPR spectra of dental enamel of 80 intact teeth from children studied. The mean square deviation of enamel sensitivity to ionizing radiation in some teeth is approximately 0.3 of the mean sensitivity value. The variability of the nature EPR spectrum of dental enamel limits in principle the lower threshold of EPR-measured 60 mGy doses. When assessing the individual absorbed doses from the EPR signal from dental enamel without additional exposure it is necessary to bear in mind the extra error of approximately 6-% at a confidence probability P=0.95 caused by the variability of enamel sensitivity to radiation in some teeth. This additional error may be ruled out by graduated additional exposure of the examined enamel samples

Light-induced lattice expansion leads to high-efficiency perovskite solar cells

Energy Technology Data Exchange (ETDEWEB)

Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C.; Durand, Olivier; Strzalka, Joseph W.; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M.; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G.; Nie, Wanyi; Mohite, Aditya D.

2018-04-05

Hybrid-perovskite based high-performance optoelectronic devices and clues from their operation has led to the realization that light-induced structural dynamics play a vital role on their physical properties, device performance and stability. Here, we report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin-films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in-situ structural and device characterizations reveal that light-induced lattice expansion significantly benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5% to 20.5%. This is a direct consequence of the relaxation of local lattice strains during lattice expansion, which results in the reduction of the energetic barriers at the perovskite/contact interfaces in devices, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion stabilizes these high-efficiency photovoltaic devices under continuous operation of full-spectrum 1-Sun illumination for over 1500 hours. One Sentence Summary: Light-induced lattice expansion improves crystallinity, relaxes lattice strain, which enhances photovoltaic performance in hybrid perovskite device.

EPR of photochromic Mo3+ in SrTiO3

NARCIS (Netherlands)

Kool, Th.W.

2010-01-01

In single crystals of SrTiO_3, a paramagnetic center, characterized by S = 3/2 and hyperfine interaction with an I = 5/2 nuclear spin has been observed in the temperature range 4.2K-77K by means of EPR. The impurity center is attributed to Mo3+. No additional line splitting in the EPR spectrum due

Seventy Years of the EPR Paradox

Science.gov (United States)

Kupczynski, Marian

2006-11-01

In spite of the fact that statistical predictions of quantum theory (QT) can only be tested if large amount of data is available a claim has been made that QT provides the most complete description of an individual physical system. Einstein's opposition to this claim and the paradox he presented in the article written together with Podolsky and Rosen in 1935 inspired generations of physicists in their quest for better understanding of QT. Seventy years after EPR article it is clear that without deep understanding of the character and limitations of QT one may not hope to find a meaningful unified theory of all physical interactions, manipulate qubits or construct a quantum computer.. In this paper we present shortly the EPR paper, the discussion, which followed it and Bell inequalities (BI). To avoid various paradoxes we advocate purely statistical contextual interpretation (PSC) of QT. According to PSC a state vector is not an attribute of a single electron, photon, trapped ion or quantum dot. A value of an observable assigned to a physical system has only a meaning in a context of a particular physical experiment PSC does not provide any mental space-time picture of sub phenomena. The EPR paradox is avoided because the reduction of the state vector in the measurement process is a passage from a description of the whole ensemble of the experimental results to a particular sub-ensemble of these results. We show that the violation of BI is neither a proof of the completeness of QT nor of its non-locality. Therefore we rephrase the EPR question and ask whether QT is "predictably "complete or in other words does it provide the complete description of experimental data. To test the "predictable completeness" it is not necessary to perform additional experiments it is sufficient to analyze more in detail the existing experimental data by using various non-parametric purity tests and other specific statistical tools invented to study the fine structure the time-series.

Pulse Double-Resonance EPR Techniques for the Study of Metallobiomolecules.

Science.gov (United States)

Cox, Nicholas; Nalepa, Anna; Pandelia, Maria-Eirini; Lubitz, Wolfgang; Savitsky, Anton

2015-01-01

Electron paramagnetic resonance (EPR) spectroscopy exploits an intrinsic property of matter, namely the electron spin and its related magnetic moment. This can be oriented in a magnetic field and thus, in the classical limit, acts like a little bar magnet. Its moment will align either parallel or antiparallel to the field, giving rise to different energies (termed Zeeman splitting). Transitions between these two quantized states can be driven by incident microwave frequency radiation, analogous to NMR experiments, where radiofrequency radiation is used. However, the electron Zeeman interaction alone provides only limited information. Instead, much of the usefulness of EPR is derived from the fact that the electron spin also interacts with its local magnetic environment and thus can be used to probe structure via detection of nearby spins, e.g., NMR-active magnetic nuclei and/or other electron spin(s). The latter is exploited in spin labeling techniques, an exciting new area in the development of noncrystallographic protein structure determination. Although these interactions are often smaller than the linewidth of the EPR experiment, sophisticated pulse EPR methods allow their detection. A number of such techniques are well established today and can be broadly described as double-resonance methods, in which the electron spin is used as a reporter. Below we give a brief description of pulse EPR methods, particularly their implementation at higher magnetic fields, and how to best exploit them for studying metallobiomolecules. © 2015 Elsevier Inc. All rights reserved.

EPR study of human hair

Czech Academy of Sciences Publication Activity Database

Křížová, Jana; Káfuňková, Eva; Stopka, Pavel

2005-01-01

Roč. 99, č. 14 (2005), s. 217-218 ISSN 0009-2770 R&D Projects: GA MZd(CZ) NL7567; GA MZd(CZ) NB7377 Institutional research plan: CEZ:AV0Z40320502 Keywords : EPR Subject RIV: CA - Inorganic Chemistry Impact factor: 0.445, year: 2005

Pharmacological and physical vessel modulation strategies to improve EPR-mediated drug targeting to tumors.

Science.gov (United States)

Ojha, Tarun; Pathak, Vertika; Shi, Yang; Hennink, Wim E; Moonen, Chrit T W; Storm, Gert; Kiessling, Fabian; Lammers, Twan

2017-09-15

The performance of nanomedicine formulations depends on the Enhanced Permeability and Retention (EPR) effect. Prototypic nanomedicine-based drug delivery systems, such as liposomes, polymers and micelles, aim to exploit the EPR effect to accumulate at pathological sites, to thereby improve the balance between drug efficacy and toxicity. Thus far, however, tumor-targeted nanomedicines have not yet managed to achieve convincing therapeutic results, at least not in large cohorts of patients. This is likely mostly due to high inter- and intra-patient heterogeneity in EPR. Besides developing (imaging) biomarkers to monitor and predict EPR, another strategy to address this heterogeneity is the establishment of vessel modulation strategies to homogenize and improve EPR. Over the years, several pharmacological and physical co-treatments have been evaluated to improve EPR-mediated tumor targeting. These include pharmacological strategies, such as vessel permeabilization, normalization, disruption and promotion, as well as physical EPR enhancement via hyperthermia, radiotherapy, sonoporation and phototherapy. In the present manuscript, we summarize exemplary studies showing that pharmacological and physical vessel modulation strategies can be used to improve tumor-targeted drug delivery, and we discuss how these advanced combination regimens can be optimally employed to enhance the (pre-) clinical performance of tumor-targeted nanomedicines. Copyright © 2017 Elsevier B.V. All rights reserved.

EPR studies of gamma-irradiated taurine single crystals

International Nuclear Information System (INIS)

Bulut, A.; Karabulut, B.; Tapramaz, R.; Koeksal, F.

2000-01-01

An EPR study of gamma-irradiated taurine [C 2 H 7 NO 3 S] single crystal was carried out at room temperature. The EPR spectra were recorded in the three at mutually perpendicular planes. There are two magnetically distinct sites in monoclinic lattice. The principle values of g and hyperfine constants for both sites were calculated. The results have indicated the presence of 32 SO - 2 and 33 SO - 2 radicals. The hyperfine values of 33 SO - 2 radical were used to obtain O-S-O bond angle for both sites

EPR Dosimetry - Present and Future

Energy Technology Data Exchange (ETDEWEB)

Regulla, D.F. [GSF - National Research Centre for Environment and Health, Institute of Radiation Protection, 85764 Neuherberg (Germany)

1999-07-01

In the past, IAEA has played a central role in stipulating research and development in EPR high-dose standardisation as well as in coordinating and organising international dose intercomparison programs, within the Member States of the United Nations from the mid-seventies till today. The future tasks of EPR dosimetry seem to tend towards different subjects such as bio markers, biological radiation effects, post-accident dose reconstruction in the environment, and retrospective human dosimetry. The latter may be considered a promising tool for epidemiology on the way to re-define radiation risk of man for chronicle radiation exposures, based on e.g. South Ural civil population and radiation workers. There are on-going international activities in the field of standardising high-level dosimetry by the American Standards on Testing and Materials (Astm), and by the International Organisation of Standards (ISO). The International Commission on Radiation Units and Measurements (ICRU) is considering the establishment of relevant recommendations concerning industrial radiation processing, but also human dose reconstruction. (Author)

EPR Dosimetry - Present and Future

International Nuclear Information System (INIS)

Regulla, D.F.

1999-01-01

In the past, IAEA has played a central role in stipulating research and development in EPR high-dose standardisation as well as in coordinating and organising international dose intercomparison programs, within the Member States of the United Nations from the mid-seventies till today. The future tasks of EPR dosimetry seem to tend towards different subjects such as bio markers, biological radiation effects, post-accident dose reconstruction in the environment, and retrospective human dosimetry. The latter may be considered a promising tool for epidemiology on the way to re-define radiation risk of man for chronicle radiation exposures, based on e.g. South Ural civil population and radiation workers. There are on-going international activities in the field of standardising high-level dosimetry by the American Standards on Testing and Materials (Astm), and by the International Organisation of Standards (ISO). The International Commission on Radiation Units and Measurements (ICRU) is considering the establishment of relevant recommendations concerning industrial radiation processing, but also human dose reconstruction. (Author)

The long way to the EPR

International Nuclear Information System (INIS)

Berke, C.

1997-01-01

At the joint conference organized by the German Kerntechnische Gesellschaft (KTG) e.V. and the French Societe Francaise d'Energie Nucleaire (SFEN) in Cologne, the announcement was made on October 20, 1997 that Jean Claude Leny will be appointed Honorary Member of KTG. For reasons of ill health the new honorary member was prevented from attending the conference. In his place, Claus Berke sketched the history of the European Pressurized Water Reactor (EPR) and presented an overview of nuclear development in France and in Germany. Developing one standard reactor model in the primary objective of German-French cooperation in reactor development. The EPR is to replace the present nuclear generating units in France and Germany after the end of their planned service life, and is to be marketed as a standard export line. (orig.) [de

In vitro Ca(2+)-dependent maturation of milk-clotting recombinant Epr: minor extracellular protease: from Bacillus licheniformis.

Science.gov (United States)

Ageitos, José Manuel; Vallejo, Juan Andrés; Serrat, Manuel; Sánchez-Pérez, Angeles; Villa, Tomás G

2013-06-01

The minor extracellular protease (Epr) is secreted into the culture medium during Bacillus licheniformis, strain USC13, stationary phase of growth. Whereas, B. subtilis Epr has been reported to be involved in swarming; the B. licheniformis protease is also involved in milk-clotting as shown by the curd forming ability of culture broths expressing this protein. The objectives of this study are the characterization of recombinant B. licheniformis Epr (minor extracellular protease) and the determination of its calcium-dependent activation process. In this work, we have cloned and expressed B. licheniformis Epr in Escherichia coli. We were also able to construct a tridimensional model for Epr based on its homology to Thermococcus kodakarensis pro-tk-subtilisin 2e1p, fervidolysin from Fervidobacterium pennivorans 1rv6, and B. lentus 1GCI subtilisin. Recombinant Epr was accumulated into inclusion bodies; after protein renaturation, Epr undergoes an in vitro calcium-dependent activation, similar to that described for tk protease. The recombinant Epr is capable of producing milk curds with the same clotting activity previously described for the native B. licheniformis Epr enzyme although further rheological and industrial studies should be carried out to confirm its real applicability. This work represents for the first time that Epr may be successfully expressed in a non-bacilli microorganism.

EPR imaging of dose distributions aiming at applications in radiation therapy

International Nuclear Information System (INIS)

Lund, E.; Kolbun, N.; Adolfsson, E.; Gustafsson, H.

2014-01-01

A one-dimensional electron paramagnetic resonance (EPR) imaging method for visualisation of dose distributions in photon fields has been developed. Pressed pellets of potassium dithionate were homogeneously irradiated in a 60 Co radiation field to 600 Gy. The EPR analysis was performed with an X-Band (9.6 GHz) Bruker E540 EPR and EPR imaging spectrometer equipped with an E540 GC2X two-axis X-band gradient coil set with gradients along the y axis (along the sample tube) and z axis (along B 0 ) and an ER 4108TMHS resonator. Image reconstruction, including deconvolution, baseline corrections and corrections for the resonator sensitivity, was performed using an in-house-developed Matlab code for the purpose to have a transparent and complete algorithm for image reconstruction. With this method, it is possible to visualise a dose distribution with an accuracy of ∼5 % within ±5 mm from the centre of the resonator. (authors)

Four-channel surface coil array for sequential CW-EPR image acquisition

Science.gov (United States)

Enomoto, Ayano; Emoto, Miho; Fujii, Hirotada; Hirata, Hiroshi

2013-09-01

This article describes a four-channel surface coil array to increase the area of visualization for continuous-wave electron paramagnetic resonance (CW-EPR) imaging. A 776-MHz surface coil array was constructed with four independent surface coil resonators and three kinds of switches. Control circuits for switching the resonators were also built to sequentially perform EPR image acquisition for each resonator. The resonance frequencies of the resonators were shifted using PIN diode switches to decouple the inductively coupled coils. To investigate the area of visualization with the surface coil array, three-dimensional EPR imaging was performed using a glass cell phantom filled with a solution of nitroxyl radicals. The area of visualization obtained with the surface coil array was increased approximately 3.5-fold in comparison to that with a single surface coil resonator. Furthermore, to demonstrate the applicability of this surface coil array to animal imaging, three-dimensional EPR imaging was performed in a living mouse with an exogenously injected nitroxyl radical imaging agent.

EPR study of sagitta otoliths of Sciaenidae fish

International Nuclear Information System (INIS)

Beneditto, Ana Paula Madeira di; Franco, Roberto Weider de Assis

2011-01-01

Full text. Otoliths are crystalline structures of calcium carbonate (CaCO 3 ) located in the inner ear of bone fish that are responsible for balance maintenance in the water column and sense of direction. The bio mineralization of these structures occurs during the fish development; when the otolith growth layers are formed. In this work, electron paramagnetic resonance (EPR) spectroscopy is applied to study the sagitta otoliths via manganese (Mn 2+ ) spectra, since in calcium carbonates the Mn 2+ ion is a natural substitutional impurity at Ca 2+ sites. The sagitta otoliths of the Sciaenidae fish Paralonchurus brasiliensis, commonly known as cabeca dura (47 samples), and Stellifer rastrifer, known as cangoa (22 samples), were obtained from specimens captured in coastal areas of Rio de Janeiro State, southeastern Brazil: Atafona (21 deg 37'S), Farol de Sao Tome (22 deg 05'S) and Rio das Ostras (22 deg 30'S). EPR spectra of sagitta otoliths were obtained in X-band (9GHz) at room temperature. The EPR spectra are typical of Mn 2+ in aragonite powder, associated to an occupation of Ca 2+ site with nine nearest neighbor oxygen atoms. It is well established in the literature that the otolith core is constituted by calcite, which is covered by aragonite during the fish growth. However, otoliths of younger fishes showed similar EPR spectra when compared to the older ones, indicating that aragonite is the main bio mineral structure in both maturity stages. In a previous work, these two Sciaenidae species presented significant differences in sagitta otoliths shape, which were related to environmental differences (e.g. water temperature, nutrients, depth) among the sampling sites (Atafona, Farol de Sao Tome and Rio das Ostras). Meanwhile, we do not observed differences in the EPR spectra, indicating that the aragonite crystallization process and the occupation of manganese are not related with the environment where these fish species are living. Then, we can infer that the

A High Sensitivity EPR Technique for Alanine Dosimetry (invited paper)

International Nuclear Information System (INIS)

Haskell, E.H.; Hayes, R.B.; Kenner, G.H.

1998-01-01

Uncertainties of ± 5 mGy were achieved in the measurement of alanine dosemeters using optimised EPR parameters, instrumentation, spectral manipulation and subtraction techniques. Modulation amplitude and microwave power were adjusted to combine resonances of two neighbouring alanine signals. Instrumental variations were minimised by combining and subtracting pre- and post-measurement spectra of the empty EPR tube. A spectrum of the native signal of non-dosed alanine was generated from a single batch of dosemeters and subtracted from spectra of the irradiated dosemeters, also from the same batch. Field alignment was adjusted with the use of an in-cavity Mn ++ standard. A constant rotation goniometer was used to eliminate anisotropies in the EPR tube and alanine samples. Finally, digital filters were applied to the resulting spectra. (author)

EPR measurements in irradiated polyacetylene

International Nuclear Information System (INIS)

Hola, O.; Foeldesova, M.

1990-01-01

The influence of γ-irradiation on the paramagnetic properties of polyacetylene, and the dependence of the EPR spectra on the radiation dose in samples of irradiated polyacetylene were studied. The measurements show that no essential changes of the spin mobility occurred during irradiation. (author) 3 refs.; 2 figs

EPR-dosimetry of ionizing radiation

Science.gov (United States)

Popova, Mariia; Vakhnin, Dmitrii; Tyshchenko, Igor

2017-09-01

This article discusses the problems that arise during the radiation sterilization of medical products. It is propose the solution based on alanine EPR-dosimetry. The parameters of spectrometer and methods of absorbed dose calculation are given. In addition, the problems that arise during heavy particles irradiation are investigated.

EPR dosimetry of cortical bone and tooth enamel irradiated with X and gamma rays: Study of energy dependence

International Nuclear Information System (INIS)

Schauer, D.A.; Links, J.M.; Desrosiers, M.F.; Le, F.G.; Seltzer, S.M.

1994-01-01

Previous investigators have reported that the radiation-induced EPR signal intensity in compact or cortical bone increases up to a factor of two with decreasing photon energy for a given absorbed dose. If the EPR signal intensity was dependent on energy, it could limit the application of EPR spectrometry and the additive reirradiation method to obtain dose estimates. We have recently shown that errors in the assumptions governing conversion of measured exposure to absorbed dose can lead to similar open-quotes apparentclose quotes energy-dependence results. We hypothesized that these previous results were due to errors in the estimated dose in bone, rather than the effects of energy dependence per se. To test this hypothesis we studied human adult cortical bone from male and female donors ranging in age from 23 to 95 years, and bovine tooth enamel, using 34 and 138 keV average energy X-ray beams and 137 Cs (662 keV) and 60 Co (1250 keV) γ rays. In a femur from a 47-year-old male (subject 1), there was a difference of borderline significance at the α = 0.05 level in the mean radiation-induced hydroxyapatite signal intensities as a function of photon energy. No other statistically significant differences in EPR signal intensity as a function of photon energy were observed in this subject, or in the tibia from a 23-year-old male (subject 2) and the femur from a 75-year-old female (subject 3). However, there was a trend toward a decrease (12-15%) in signal intensity at the lowest energy compared with the highest energy in subjects 1 and 3. Further analysis of the data from subject 1 revealed that this trend, which is in the opposite direction of previous reports but is consistent with theory, is statistically significant. There were no efforts of energy dependence in the tooth samples. 16 refs., 7 figs., 5 tabs

EPR dosimetric properties of nano-barium sulfate

International Nuclear Information System (INIS)

Aboelezz, E.; Hassan, G.M.; Sharaf, M.A.; El-Khodary, A.

2015-01-01

Nano/micro BaSO 4 were prepared through the co-precipitation method to measure ionizing radiation doses using electron paramagnetic resonance (EPR). The nano-BaSO 4 sample was characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The dose response and fading properties of nano- and micro-phase BaSO 4 were compared in EPR spectra. The prepared nano- and micro-BaSO 4 samples have the same hole and electron centers, which may be attributed to SO 4 − and SO 3 − , respectively. The dosimetric signals for prepared nano- and micro-BaSO 4 have spectroscopic splitting factor (g) with values 2.0025±0.0006 and 2.0027±0.0006, respectively. The nanocrystalline sample has a linear γ-ray dose response over the range 0.4 Gy–1 kGy. The performance parameters which including detection limit and critical level calculated from weighted and unweighted least-squares fitting. The sensitivity of nano-BaSO 4 to γ-ray is one and a half times more than alanine. The lifetime and activation energy for nano-BaSO 4 were estimated by conducting a thermal stability study, and were 5.7±1.1×10 4 years and 0.73±0.14 eV, respectively. The combined and expanded uncertainties accompanying measurements were ±3.89% and ±7.78%, respectively. - Highlights: • Preparation of nano-BaSO 4 using the co-precipitation method. • Study of the dosimetric properties of nano-barium sulfate using the EPR technique. • Comparison between a new EPR dosimeter using nano-materials and standard alanine. • Calculation of the uncertainty budget for nano-BaSO 4

Alanine-EPR as a transfer standard dosimetry system for low energy X radiation

International Nuclear Information System (INIS)

Khoury, H.J.; Silva, E.J. da; Mehta, K.; Barros, V.S. de; Asfora, V.K.; Guzzo, P.L.; Parker, A.G.

2015-01-01

The purpose of this paper is to evaluate the use of alanine-EPR as a transfer standard dosimetry system for low energy X radiation, such as that in RS-2400, which operates in the range from 25 to 150 kV and 2 to 45 mA. Two types of alanine dosimeters were investigated. One is a commercial alanine pellets from Aérial-Centre de Ressources Technologiques, France and one was prepared in our laboratory (LMRI-DEN/UFPE). The EPR spectra of the irradiated dosimeters were recorded in the Nuclear Energy Department of UFPE, using a Bruker EMX10 EPR spectrometer operating in the X-band. The alanine-EPR dosimetry system was calibrated in the range of 20–220 Gy in this X-ray field, against an ionization chamber calibrated at the relevant X-ray energy with traceability to PTB. The results showed that both alanine dosimeters presented a linear dose response the same sensitivity, when the EPR signal was normalized to alanine mass. The total uncertainty in the measured dose was estimated to be about 3%. The results indicate that it is possible to use the alanine-EPR dosimetry system for validation of a low-energy X ray irradiator, such as RS-2400.

Characterization of beer flavour stability (EPR - spin trapping)

International Nuclear Information System (INIS)

Stasko, A.; Liptakova, M.; Malik, F.

1999-01-01

The beer flavour stability is coupled with free radical degradation processes. Probably, aldehydes produced during the brewery but also generated by stalling are responsible for beer flavour as well as for its breaking down. The storing beer at the lower temperatures and in the dark place inhibits, and otherwise the rising temperature and illumination accelerate the rate of such radical processes. Beers contain naturally occurring radical scavengers - antioxidants which inhibit such unwanted reactions. Then depleting of scavengers results in the breaking down of the beer stability. EPR spin trapping technique was used as monitor such processes and for characterising so the flavour stability of beer. The probe was temperated at 60 grad C in the cavity of EPR spectrometer in the presence of spin trapping agent, N-tert.-butyl-α-phenyl nitrone (PBN) and EPR spectra were recorded for few hours. After beer antioxidants become depleted, free radicals formed by the beer degradation are scavenged by PBN spin trap and this point is characterised with a dramatically increased concentration of the free radicals trapped

Radiation sensitivity and EPR dosimetric potential of gallic acid and its esters

International Nuclear Information System (INIS)

Tuner, Hasan; Oktay Bal, M.; Polat, Mustafa

2015-01-01

In the preset work the radiation sensitivities of Gallic Acid anhydrous and monohydrate, Octyl, Lauryl, and Ethyl Gallate (GA, GAm, OG, LG, and EG) were investigated in the intermediate (0.5–20 kGy) and low radiation (<10 Gy) dose range using Electron Paramagnetic Resonance (EPR) spectroscopy. While OG, LG, and EG are presented a singlet EPR spectra, their radiation sensitivity found to be very different in the intermediate dose range. At low radiation dose range (<10 Gy) only LG is found to be present a signal that easily distinguished from the noise signals. The intermediate and low dose range radiation sensitivities are compared using well known EPR dosimeter alanine. The radiation yields (G) of the interested material were found to be 1.34×10 −2 , 1.48×10 −2 , 4.14×10 −2 , and 6.03×10 −2 , 9.44×10 −2 for EG, GA, GAm, OG, and LG, respectively at the intermediate dose range. It is found that the simple EPR spectra and the noticeable EPR signal of LG make it a promising dosimetric material to be used below 10 Gy of radiation dose. - Highlights: • Radiation sensitivity of gallic acid and its esters were studied in intermediate and low radiation dose range using EPR. • While the irradiated samples of GA were presented complex EPR spectra the esters presented singlet ESR spectra. • Samples were compared to alanine in terms of the dosimetric point of view. • The radiation sensitivities of the investigated materials were very low at intermediate doses. • Lauryl ester of gallic acid was found to present a good sensitivity below 10 Gy

ER=EPR, GHZ, and the consistency of quantum measurements

International Nuclear Information System (INIS)

Susskind, Leonard

2016-01-01

This paper illustrates various aspects of the ER=EPR conjecture. It begins with a brief heuristic argument, using the Ryu-Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein-Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger-Horne-Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

ER=EPR, GHZ, and the consistency of quantum measurements

Energy Technology Data Exchange (ETDEWEB)

Susskind, Leonard [Stanford Institute for Theoretical Physics and Department of Physics, Stanford University, Stanford, CA (United States)

2016-01-15

This paper illustrates various aspects of the ER=EPR conjecture. It begins with a brief heuristic argument, using the Ryu-Takayanagi correspondence, for why entanglement between black holes implies the existence of Einstein-Rosen bridges. The main part of the paper addresses a fundamental question: Is ER=EPR consistent with the standard postulates of quantum mechanics? Naively it seems to lead to an inconsistency between observations made on entangled systems by different observers. The resolution of the paradox lies in the properties of multiple black holes, entangled in the Greenberger-Horne-Zeilinger pattern. The last part of the paper is about entanglement as a resource for quantum communication. ER=EPR provides a way to visualize protocols like quantum teleportation. In some sense teleportation takes place through the wormhole, but as usual, classical communication is necessary to complete the protocol. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Probing Microenvironment in Ionic Liquids by Time-Resolved EPR of Photoexcited Triplets.

Science.gov (United States)

Ivanov, M Yu; Veber, S L; Prikhod'ko, S A; Adonin, N Yu; Bagryanskaya, E G; Fedin, M V

2015-10-22

Unusual physicochemical properties of ionic liquids (ILs) open vistas for a variety of new applications. Herewith, we investigate the influence of microviscosity and nanostructuring of ILs on spin dynamics of the dissolved photoexcited molecules. We use two most common ILs [Bmim]PF6 and [Bmim]BF4 (with its close analogue [C10mim]BF4) as solvents and photoexcited Zn tetraphenylporphyrin (ZnTPP) as a probe. Time-resolved electron paramagnetic resonance (TR EPR) is employed to investigate spectra and kinetics of spin-polarized triplet ZnTPP in the temperature range 100-270 K. TR EPR data clearly indicate the presence of two microenvironments of ZnTPP in frozen ILs at 100-200 K, being manifested in different spectral shapes and different spin relaxation rates. For one of these microenvironments TR EPR data is quite similar to those obtained in common frozen organic solvents (toluene, glycerol, N-methyl-2-pyrrolidone). However, the second one favors the remarkably slow relaxation of spin polarization, being much longer than in the case of common solvents. Additional experiments using continuous wave EPR and stable nitroxide as a probe confirmed the formation of heterogeneities upon freezing of ILs and complemented TR EPR results. Thus, TR EPR of photoexcited triplets can be effectively used for probing heterogeneities and nanostructuring in frozen ILs. In addition, the increase of polarization lifetime in frozen ILs is an interesting finding that might allow investigation of short-lived intermediates inaccessible otherwise.

EPR (European Pressurized water Reactor) The advanced nuclear reactor

International Nuclear Information System (INIS)

2004-01-01

Nuclear energy, which provides a steady supply of electricity at low cost, has its rightful place in the energy mix of the 21. century, which puts the emphasis on sustainable development. The EPR is the only 3. generation reactor under construction today. It is an evolutionary reactor that represents a new generation of pressurized water reactors with no break in the technology used for the most recent models. The EPR was developed by Framatome and Siemens, whose nuclear activities were combined in January 2001 to form Framatome ANP, a subsidiary of AREVA and Siemens. EDF and the major German electricity companies played an active part in the project. The safety authorities of the two countries joined forces to bring their respective safety standards into line and draw up joint design rules for the new reactor. The project had three objectives: meet the requirements of European utilities, comply with the safety standards laid down by the French safety authority for future pressurized water reactors, in concert with its German counterpart, and make nuclear energy even more competitive than energy generated using fossil fuels. The EPR can guarantee a safe, inexpensive electricity supply, without adding to the greenhouse effect. It meets the requirements of the safety authorities and lives up to the expectations of electricity utilities. This document presents the main characteristics of the EPR, and in particular the additional measures to prevent the occurrence of events likely to damage the core, the leak-tight containment, the measures to reduce the exposure of operating and maintenance personnel, the solutions for an even greater protection of the environment. The foreseen development of the EPR in France and abroad (Finland, China, the United States) is summarized

Radiation sensitivity and EPR dosimetric potential of gallic acid and its esters

Science.gov (United States)

Tuner, Hasan; Oktay Bal, M.; Polat, Mustafa

2015-02-01

In the preset work the radiation sensitivities of Gallic Acid anhydrous and monohydrate, Octyl, Lauryl, and Ethyl Gallate (GA, GAm, OG, LG, and EG) were investigated in the intermediate (0.5-20 kGy) and low radiation (<10 Gy) dose range using Electron Paramagnetic Resonance (EPR) spectroscopy. While OG, LG, and EG are presented a singlet EPR spectra, their radiation sensitivity found to be very different in the intermediate dose range. At low radiation dose range (<10 Gy) only LG is found to be present a signal that easily distinguished from the noise signals. The intermediate and low dose range radiation sensitivities are compared using well known EPR dosimeter alanine. The radiation yields (G) of the interested material were found to be 1.34×10-2, 1.48×10-2, 4.14×10-2, and 6.03×10-2, 9.44×10-2 for EG, GA, GAm, OG, and LG, respectively at the intermediate dose range. It is found that the simple EPR spectra and the noticeable EPR signal of LG make it a promising dosimetric material to be used below 10 Gy of radiation dose.

Internal fire protection analysis for the United Kingdom EPR design

Energy Technology Data Exchange (ETDEWEB)

Laid, Abdallah [Nuclear New Build Generation Company Ltd. (NNB GenCo), Barnwood (United Kingdom). EDF Energy Plc.; Cesbron, Mickael [Service Etudes et Project Thermiques et Nucleaires (SEPTEN), Lyon (France). EDF-SA

2015-12-15

In the deterministic design basis analysis of the United Kingdom (UK) EPR based nuclear power plants all postulated initiating events are grouped into two different types, internal faults and internal/external hazards. ''Internal Fires'' is one of the internal hazards analysed at the design stage of the UK EPR. In effect, the main safety objective for fire protection is to ensure that all the required safety functions are performed in the event of an internal fire. To achieve this safety objective, provisions for protection against fire risks are taken to: (i) limit the spread of a fire, protect the safety functions of the facility; (ii) limit the propagation of smoke and dispersion of toxic, radioactive, inflammable, corrosive or explosive materials, and (iii) ensure the achievement of a safe shutdown state, personnel evacuation and all other necessary emergency actions. This paper presents the UK EPR approach on how the above provisions are applied. Such provisions involve implementing means of fire prevention, surveillance, firefighting and limiting fire consequences, appropriate to the risks inherent to the facility. Overall, the design of the UK EPR fire protection systems is based on three types of measures: prevention, containment and control.

USE OF-EPR-DL FIELD TEST EQUIPMENT FOR DETECTION OF SIGMA PHASE

Directory of Open Access Journals (Sweden)

Abraão Danilo Gomes Barreto

2014-06-01

Full Text Available This work has objective to correlate the intergranular corrosion susceptibility test named EPR-DL (Electrochemical Potentiokinetic Reactivation of Double Loop with the sigma phase formation and other phases. It has been used samples from a UNS S32760 steel pipe for conducting various aging heat treatments. Held isothermal heat treatment at 850°C for 1 min, 10 min, 30 min, 1 h, 1h30min and 10 h. Each heat treated sample and as received were tested using the electrochemical polarization reactivation of double loop technique (EPR-DL. It was possible the detection of deleterious phases with DL-EPR portable cell. The EPR-DL test of some samples showed a second peak of reactivation in which the results showed that this peak might be associated with ferrite or be related to the presence of chi phase

Organ specific mapping of in vivo redox state in control and cigarette smoke-exposed mice using EPR/NMR co-imaging

Science.gov (United States)

Caia, George L.; Efimova, Olga V.; Velayutham, Murugesan; El-Mahdy, Mohamed A.; Abdelghany, Tamer M.; Kesselring, Eric; Petryakov, Sergey; Sun, Ziqi; Samouilov, Alexandre; Zweier, Jay L.

2014-01-01

In vivo mapping of alterations in redox status is important for understanding organ specific pathology and disease. While electron paramagnetic resonance imaging (EPRI) enables spatial mapping of free radicals, it does not provide anatomic visualization of the body. Proton MRI is well suited to provide anatomical visualization. We applied EPR/NMR co-imaging instrumentation to map and monitor the redox state of living mice under normal or oxidative stress conditions induced by secondhand cigarette smoke (SHS) exposure. A hybrid co-imaging instrument, EPRI (1.2 GHz) / proton MRI (16.18 MHz), suitable for whole-body co-imaging of mice was utilized with common magnet and gradients along with dual EPR/NMR resonators that enable co-imaging without sample movement. The metabolism of the nitroxide probe, 3–carbamoyl–proxyl (3-CP), was used to map the redox state of control and SHS-exposed mice. Co-imaging allowed precise 3D mapping of radical distribution and reduction in major organs such as the heart, lungs, liver, bladder and kidneys. Reductive metabolism was markedly decreased in SHS-exposed mice and EPR/NMR co-imaging allowed quantitative assessment of this throughout the body. Thus, in vivo EPR/NMR co-imaging enables in vivo organ specific mapping of free radical metabolism and redox stress and the alterations that occur in the pathogenesis of disease. PMID:22296801

Polypropylene/ethylene-propylene rubber (PP/EPR blends for the automotive industry: Basic correlations between EPR-design and shrinkage

Directory of Open Access Journals (Sweden)

G. D. Potter

2014-04-01

Full Text Available The influence of the phase morphology on the shrinkage of injection molded plates from reactor based PP/EPR blends was investigated using a model series. The morphology of the dispersed phase – in terms of size and shape of the rubber particles as determined from scanning electron microscopy (SEM – was found to correlate fairly well with the shrinkage determined in the flow and transverse direction of injection molded plates. In this respect it turned out to be elementary to consider the anisotropy of the particles rather than their average size alone. Additionally, the effect of the EPR design on the coefficient of linear thermal expansion (CLTE was evaluated and brought into a relationship with the blend morphology.

THE VIEW FROM THE TRENCHES: PART 2–TECHNICAL CONSIDERATIONS FOR EPR SCREENING

Science.gov (United States)

Nicolalde, Roberto J.; Gougelet, Robert M.; Rea, Michael; Williams, Benjamin B.; Dong, Ruhong; Kmiec, Maciej M.; Lesniewski, Piotr N.; Swartz, Harold M.

2014-01-01

There is growing awareness of the need for methodologies that can be used retrospectively to provide the biodosimetry needed to carry out screening and triage immediately after an event in which large numbers of people have potentially received clinically significant doses of ionizing radiation. The general approach to developing such methodologies has been a technology centric one, often ignoring the system integrations considerations that are key to their effective use. In this study an integrative approach for the evaluation and development of a physical biodosimetry technology was applied based on in vivo electron paramagnetic resonance (EPR) dosimetry. The EPR measurements are based on physical changes in tissues whose magnitudes are not affected by the factors that can confound biologically-based assessments. In this study the use of a pilot simulation exercise to evaluate an experimental EPR system and gather stakeholders’ feedback early on in the development process is described. The exercise involved: ten non-irradiated participants, representatives from a local fire department; Department of Homeland Security certified exercise evaluators, EPR experts, physicians; and a human factors engineer. Stakeholders were in agreement that the EPR technology in its current state of development could be deployed for the screening of mass casualties. Furthermore, stakeholders’ recommendations will be prioritized and incorporated in future developments of the EPR technique. While the results of this exercise were aimed specifically at providing feedback for the development of EPR dosimetry for screening mass casualties, the methods and lessons learned are likely to be applicable to other biodosimetric methods. PMID:20065674

Light-induced atomic desorption and related phenomena

Energy Technology Data Exchange (ETDEWEB)

Burchianti, A; Bogi, A; Marinelli, C; Mariotti, E; Moi, L [CNISM and Physics Department, University of Siena, 53100 Siena (Italy)], E-mail: burchianti@unisi.it

2009-07-15

We review some recent studies on light-induced atomic desorption (LIAD) from dielectric surfaces. Alkali-metal atoms adsorbed either on organic films or on porous glass are released into the vapor phase under illumination. The measurements were performed in Pyrex resonance cells either coated with siloxane films or containing a porous glass sample. In both cases, the experimental results show that LIAD can be used to produce atomic densities suitable for most atomic physics experiments. Moreover, we find that photoinduced effects, correlated with LIAD, produce reversible formation and evaporation of alkali-metal clusters in porous glass. These processes depend on the light frequency, making the porous glass transmittance controllable by light.

Accelerated dynamic EPR imaging using fast acquisition and compressive recovery.

Science.gov (United States)

Ahmad, Rizwan; Samouilov, Alexandre; Zweier, Jay L

2016-12-01

Electron paramagnetic resonance (EPR) allows quantitative imaging of tissue redox status, which provides important information about ischemic syndromes, cancer and other pathologies. For continuous wave EPR imaging, however, poor signal-to-noise ratio and low acquisition efficiency limit its ability to image dynamic processes in vivo including tissue redox, where conditions can change rapidly. Here, we present a data acquisition and processing framework that couples fast acquisition with compressive sensing-inspired image recovery to enable EPR-based redox imaging with high spatial and temporal resolutions. The fast acquisition (FA) allows collecting more, albeit noisier, projections in a given scan time. The composite regularization based processing method, called spatio-temporal adaptive recovery (STAR), not only exploits sparsity in multiple representations of the spatio-temporal image but also adaptively adjusts the regularization strength for each representation based on its inherent level of the sparsity. As a result, STAR adjusts to the disparity in the level of sparsity across multiple representations, without introducing any tuning parameter. Our simulation and phantom imaging studies indicate that a combination of fast acquisition and STAR (FASTAR) enables high-fidelity recovery of volumetric image series, with each volumetric image employing less than 10 s of scan. In addition to image fidelity, the time constants derived from FASTAR also match closely to the ground truth even when a small number of projections are used for recovery. This development will enhance the capability of EPR to study fast dynamic processes that cannot be investigated using existing EPR imaging techniques. Copyright © 2016 Elsevier Inc. All rights reserved.

EPR studies of gamma-irradiated taurine single crystals

Energy Technology Data Exchange (ETDEWEB)

Bulut, A. E-mail: abulut@samsun.omu.edu.tr; Karabulut, B.; Tapramaz, R.; Koeksal, F

2000-04-01

An EPR study of gamma-irradiated taurine [C{sub 2}H{sub 7}NO{sub 3}S] single crystal was carried out at room temperature. The EPR spectra were recorded in the three at mutually perpendicular planes. There are two magnetically distinct sites in monoclinic lattice. The principle values of g and hyperfine constants for both sites were calculated. The results have indicated the presence of {sup 32}SO{sup -}{sub 2} and {sup 33}SO{sup -}{sub 2} radicals. The hyperfine values of {sup 33}SO{sup -}{sub 2} radical were used to obtain O-S-O bond angle for both sites.

EPR and TL correlation in some powdered Greek white marbles

International Nuclear Information System (INIS)

Baieetto, Vanessa; Villeneuve, Gerard; Guibert, Pierre; Schvoerer, Max

2000-01-01

Thermoluminescence of white powdered marble samples, chosen to display different EPR spectra, were studied. Two peaks at 280 deg. C and 360 deg. C can be observed among the TL glow curves while the EPR spectra exhibit two signals: the A signal with g perp =2.0038 and g par =2.0024 due to the SO - 3 centre and the B one with g 1 =2.0005; g 2 =2.0001; g 3 =1.9998 due to mechanical powder reduction (drilling). Owing to heating and simultaneous experiments, a correlation have been established: the 280 deg. C TL peak is associated to the A signal and thus to the SO - 3 centre and the 360 deg. C TL peak is caused by mechanical treatment corresponding to the B EPR signal

EPR and TL correlation in some powdered Greek white marbles.

Science.gov (United States)

Baïetto, V; Villeneuve, G; Guibert, P; Schvoerer, M

2000-02-01

Thermoluminescence of white powdered marble samples, chosen to display different EPR spectra, were studied. Two peaks at 280 degrees C and 360 degrees C can be observed among the TL glow curves while the EPR spectra exhibit two signals: the A signal with g perpendicular = 2.0038 and g parallel = 2.0024 due to the SO3- centre and the B one with g1 = 2.0005; g2 = 2.0001; g3 = 1.9998 due to mechanical powder reduction (drilling). Owing to heating and simultaneous experiments, a correlation have been established: the 280 degrees C TL peak is associated to the A signal and thus to the SO3- centre and the 360 degrees C TL peak is caused by mechanical treatment corresponding to the B EPR signal.

Study for applying microwave power saturation technique on fingernail/EPR dosimetry

Energy Technology Data Exchange (ETDEWEB)

Park, Byeong Ryong; Choi, Hoon; Nam, Hyun Ill; Lee, Byung Ill [Radiation Health Research Institute, Seoul (Korea, Republic of)

2012-10-15

There is growing recognition worldwide of the need to develop effective uses of dosimetry methods to assess unexpected exposure to radiation in the event of a large scale event. One of physically based dosimetry methods electron paramagnetic resonance (EPR) spectroscopy has been applied to perform retrospective radiation dosimetry using extracted samples of tooth enamel and nail(fingernail and toenail), following radiation accidents and exposures resulting from weapon use, testing, and production. Human fingernails are composed largely of a keratin, which consists of {alpha} helical peptide chains that are twisted into a left handed coil and strengthened by disulphide cross links. Ionizing radiation generates free radicals in the keratin matrix, and these radicals are stable over a relatively long period (days to weeks). Most importantly, the number of radicals is proportional to the magnitude of the dose over a wide dose range (0{approx}30 Gy). Also, dose can be estimated at four different locations on the human body, providing information on the homogeneity of the radiation exposure. And The results from EPR nail dosimetry are immediately available However, relatively large background signal (BKS) converted from mechanically induced signal (MIS) after cutting process of fingernail, normally overlaps with the radiation induced signal (RIS), make it difficult to estimate accurate dose accidental exposure. Therefore, estimation method using dose response curve was difficult to ensure reliability below 5 Gy. In this study, In order to overcome these disadvantages, we measured the reactions of RIS and BKS (MIS) according to the change of Microwave power level, and researched about the applicability of the Power saturation technique at low dose.

Skew Projection of Echo-Detected EPR Spectra for Increased Sensitivity and Resolution

Science.gov (United States)

Bowman, Michael K.; Krzyaniak, Matthew D.; Cruce, Alex A.; Weber, Ralph T.

2013-01-01

The measurement of EPR spectra during pulsed EPR experiments is commonly accomplished by recording the integral of the electron spin echo as the applied magnetic field is stepped through the spectrum. This approach to echo-detected EPR spectral measurement (ED-EPR) limits sensitivity and spectral resolution and can cause gross distortions in the resulting spectra because some of the information present in the electron spin echo is discarded in such measurements. However, Fourier Transformation of echo shapes measured at a series of magnetic field values followed by skew projection onto either a magnetic field or resonance frequency axis can increase both spectral resolution and sensitivity without the need to trade one against the other. Examples of skew-projected spectra with single crystals, glasses and powders show resolution improvements as large as a factor of seven with sensitivity increases of as much as a factor of five. PMID:23644351

Laser induced white lighting of tungsten filament

Science.gov (United States)

Strek, W.; Tomala, R.; Lukaszewicz, M.

2018-04-01

The sustained bright white light emission of thin tungsten filament was induced under irradiation with focused beam of CW infrared laser diode. The broadband emission centered at 600 nm has demonstrated the threshold behavior on excitation power. Its intensity increased non-linearly with excitation power. The emission occurred only from the spot of focused beam of excitation laser diode. The white lighting was accompanied by efficient photocurrent flow and photoelectron emission which both increased non-linearly with laser irradiation power.

Press kit. EPR (European pressurized water reactor). The advanced nuclear reactor

International Nuclear Information System (INIS)

2004-10-01

Nuclear energy, which provides a steady supply of electricity at low cost, has its rightful place in the energy mix of the 21 century, which puts the emphasis on sustainable development. In this framework, this document presents the advantages of the EPR (European Pressurized water Reactor). The EPR is the only third generation reactor under construction today. It is an evolutionary reactor that represents a new generation of pressurized water reactors with no break in the technology used for the most recent models. The EPR can guarantee a safe, inexpensive electricity supply, without adding to the greenhouse effect. It meets the requirements of the safety authorities and lives up to the expectations of electricity utilities. (A.L.B.)

Trichloroethylene Radicals: An EPR/SPIN Trapping Study

National Research Council Canada - National Science Library

Steel-Goodwin, Linda

1995-01-01

.... As part of the process to develop environmental and health effects criteria for base clean-up the initial radicals produced by TCE were studied by electron paramagnetic resonance spectroscopy (EPR...

EPR measurements of phenolic concentration in developing red grapeseeds - a pilot study

International Nuclear Information System (INIS)

Troup, G.J.; Kennedy, J.A.; Hutton, D.R.; Hewitt, D.; Hunter, C.A.; Pilbrow, J.R.; Ristic, R.; Iland, P.; Jones, G.P. Anon

2000-01-01

Full text: Phenolics, in the liquid (wine, Troup et al., Free Radicals Research, 1994, 20, 63 - 68) and solid state, give stable free radical signals detectable by EPR. Observations of EPR signals (partly due to phenolics) in developing red grapeseeds, as a function of time, have been made. The increasing, then decreasing of this signal as a function of time correlates well with the theory of phenolic concentration in developing grapeseeds recently proposed by Kennedy et al. (in press). This is a very significant application of EPR Spectroscopy in the Wine Industry, so far unfamiliar with its use

Design adaptation to the local context - Example of the UK EPR

International Nuclear Information System (INIS)

Dupuis, Joseph

2014-01-01

The Chief Executive Officer of SOFINEL, Joseph Dupuis, explained how the EPR design was adapted to the UK context and, in particular, the main modifications that were implemented to conform with UK specific regulations. He also presented the cultural and/or technical differences that had to be taken into account for managing the UK EPR project

Steering, Entanglement, Nonlocality, and the EPR Paradox

Science.gov (United States)

Wiseman, Howard; Jones, Steve; Andrew, Doherty

2007-06-01

The concept of steering was introduced by Schroedinger in 1935 as a generalization of the EPR paradox for arbitrary pure bipartite entangled states and arbitrary measurements by one party. Until now, it has never been rigorously defined, so it has not been known (for example) what mixed states are steerable (that is, can be used to exhibit steering). We provide an operational definition, from which we prove (by considering Werner states and Isotropic states) that steerable states are a strict subset of the entangled states, and a strict superset of the states that can exhibit Bell-nonlocality. For arbitrary bipartite Gaussian states we derive a linear matrix inequality that decides the question of steerability via Gaussian measurements, and we relate this to the original EPR paradox.

EPR dosimetry - present and future

International Nuclear Information System (INIS)

Regulla, D.F.

1999-01-01

In the past, IAEA has played a central role in stipulating research and development in EPR high-dose standardisation as well as co-ordinating and organising international dose intercomparison programs, within the Member States of the United Nations from the mid-seventies till today. The future tasks of EPR dosimetry seem to tend towards different subjects such as biomarkers, biological radiation effects, post-accident dose reconstruction in the environment, and retrospective human dosimetry. The latter may be considered a promising tool for epidemiology on the way to re-define radiation risk of man for chronicle radiation exposures, based on e.g. South Ural civil population and radiation workers. There are on-going international activities in the field of standardising high-level dosimetry by the American Standards on Testing and Materials (ASTM), and the International Organisation of Standards (ISO) as well as those of the International Commission on Radiation Units and Measurements (ICRU) considering the establishment of relevant recommendations concerning industrial radiation processing, but also human dose reconstruction. (author)

CW EPR parameters reveal cytochrome P450 ligand binding modes.

Science.gov (United States)

Lockart, Molly M; Rodriguez, Carlo A; Atkins, William M; Bowman, Michael K

2018-06-01

Cytochrome P450 (CYP) monoxygenses utilize heme cofactors to catalyze oxidation reactions. They play a critical role in metabolism of many classes of drugs, are an attractive target for drug development, and mediate several prominent drug interactions. Many substrates and inhibitors alter the spin state of the ferric heme by displacing the heme's axial water ligand in the resting enzyme to yield a five-coordinate iron complex, or they replace the axial water to yield a nitrogen-ligated six-coordinate iron complex, which are traditionally assigned by UV-vis spectroscopy. However, crystal structures and recent pulsed electron paramagnetic resonance (EPR) studies find a few cases where molecules hydrogen bond to the axial water. The water-bridged drug-H 2 O-heme has UV-vis spectra similar to nitrogen-ligated, six-coordinate complexes, but are closer to "reverse type I" complexes described in older liteature. Here, pulsed and continuous wave (CW) EPR demonstrate that water-bridged complexes are remarkably common among a range of nitrogenous drugs or drug fragments that bind to CYP3A4 or CYP2C9. Principal component analysis reveals a distinct clustering of CW EPR spectral parameters for water-bridged complexes. CW EPR reveals heterogeneous mixtures of ligated states, including multiple directly-coordinated complexes and water-bridged complexes. These results suggest that water-bridged complexes are under-represented in CYP structural databases and can have energies similar to other ligation modes. The data indicates that water-bridged binding modes can be identified and distinguished from directly-coordinated binding by CW EPR. Copyright © 2018 Elsevier Inc. All rights reserved.

EPR study of sagitta otoliths of Sciaenidae fish

Energy Technology Data Exchange (ETDEWEB)

Beneditto, Ana Paula Madeira di; Franco, Roberto Weider de Assis [Universidade Estadual do Norte Fluminense (UENF), RJ (Brazil)

2011-07-01

Full text. Otoliths are crystalline structures of calcium carbonate (CaCO{sub 3}) located in the inner ear of bone fish that are responsible for balance maintenance in the water column and sense of direction. The bio mineralization of these structures occurs during the fish development; when the otolith growth layers are formed. In this work, electron paramagnetic resonance (EPR) spectroscopy is applied to study the sagitta otoliths via manganese (Mn{sup 2+}) spectra, since in calcium carbonates the Mn{sup 2+} ion is a natural substitutional impurity at Ca{sup 2+} sites. The sagitta otoliths of the Sciaenidae fish Paralonchurus brasiliensis, commonly known as cabeca dura (47 samples), and Stellifer rastrifer, known as cangoa (22 samples), were obtained from specimens captured in coastal areas of Rio de Janeiro State, southeastern Brazil: Atafona (21 deg 37'S), Farol de Sao Tome (22 deg 05'S) and Rio das Ostras (22 deg 30'S). EPR spectra of sagitta otoliths were obtained in X-band (9GHz) at room temperature. The EPR spectra are typical of Mn{sup 2+} in aragonite powder, associated to an occupation of Ca{sup 2+} site with nine nearest neighbor oxygen atoms. It is well established in the literature that the otolith core is constituted by calcite, which is covered by aragonite during the fish growth. However, otoliths of younger fishes showed similar EPR spectra when compared to the older ones, indicating that aragonite is the main bio mineral structure in both maturity stages. In a previous work, these two Sciaenidae species presented significant differences in sagitta otoliths shape, which were related to environmental differences (e.g. water temperature, nutrients, depth) among the sampling sites (Atafona, Farol de Sao Tome and Rio das Ostras). Meanwhile, we do not observed differences in the EPR spectra, indicating that the aragonite crystallization process and the occupation of manganese are not related with the environment where these fish species

High-pressure EPR spectroscopy studies of the E. coli lipopolysaccharide transport proteins LptA and LptC.

Science.gov (United States)

Schultz, Kathryn M; Klug, Candice S

2017-12-01

The use of pressure is an advantageous approach to the study of protein structure and dynamics because it can shift the equilibrium populations of protein conformations toward higher energy states that are not of sufficient population to be observable at atmospheric pressure. Recently, the Hubbell group at the University of California, Los Angeles, reintroduced the application of high pressure to the study of proteins by electron paramagnetic resonance (EPR) spectroscopy. This methodology is possible using X-band EPR spectroscopy due to advances in pressure intensifiers, sample cells, and resonators. In addition to the commercial availability of the pressure generation and sample cells by Pressure Biosciences Inc., a five-loop-four-gap resonator required for the initial high pressure EPR spectroscopy experiments by the Hubbell group, and those reported here, was designed by James S. Hyde and built and modified at the National Biomedical EPR Center. With these technological advances, we determined the effect of pressure on the essential periplasmic lipopolysaccharide (LPS) transport protein from Escherichia coli , LptA, and one of its binding partners, LptC. LptA unfolds from the N-terminus to the C-terminus, binding of LPS does not appreciably stabilize the protein under pressure, and monomeric LptA unfolds somewhat more readily than oligomeric LptA upon pressurization to 2 kbar. LptC exhibits a fold and relative lack of stability upon LPS binding similar to LptA, yet adopts an altered, likely monomeric, folded conformation under pressure with only its C-terminus unraveling. The pressure-induced changes likely correlate with functional changes associated with binding and transport of LPS.

Light-induced lattice expansion leads to high-efficiency perovskite solar cells

Science.gov (United States)

Tsai, Hsinhan; Asadpour, Reza; Blancon, Jean-Christophe; Stoumpos, Constantinos C.; Durand, Olivier; Strzalka, Joseph W.; Chen, Bo; Verduzco, Rafael; Ajayan, Pulickel M.; Tretiak, Sergei; Even, Jacky; Alam, Muhammad Ashraf; Kanatzidis, Mercouri G.; Nie, Wanyi; Mohite, Aditya D.

2018-04-01

Light-induced structural dynamics plays a vital role in the physical properties, device performance, and stability of hybrid perovskite–based optoelectronic devices. We report that continuous light illumination leads to a uniform lattice expansion in hybrid perovskite thin films, which is critical for obtaining high-efficiency photovoltaic devices. Correlated, in situ structural and device characterizations reveal that light-induced lattice expansion benefits the performances of a mixed-cation pure-halide planar device, boosting the power conversion efficiency from 18.5 to 20.5%. The lattice expansion leads to the relaxation of local lattice strain, which lowers the energetic barriers at the perovskite-contact interfaces, thus improving the open circuit voltage and fill factor. The light-induced lattice expansion did not compromise the stability of these high-efficiency photovoltaic devices under continuous operation at full-spectrum 1-sun (100 milliwatts per square centimeter) illumination for more than 1500 hours.

Holographic EPR pairs, wormholes and radiation

Science.gov (United States)

Chernicoff, Mariano; Güijosa, Alberto; Pedraza, Juan F.

2013-10-01

As evidence for the ER = EPR conjecture, it has recently been observed that the string that is holographically dual to an entangled quark-antiquark pair separating with (asymptotically) uniform acceleration has a wormhole on its worldsheet. We point out that a two-sided horizon and a wormhole actually appear for much more generic quark-antiquark trajectories, which is consistent with the fact that the members of an EPR pair need not be permanently out of causal contact. The feature that determines whether the causal structure of the string worldsheet is trivial or not turns out to be the emission of gluonic radiation by the dual quark and antiquark. In the strongly-coupled gauge theory, it is only when radiation is emitted that one obtains an unambiguous separation of the pair into entangled subsystems, and this is what is reflected on the gravity side by the existence of the worldsheet horizon.

EPR and TL correlation in some powdered Greek white marbles

Energy Technology Data Exchange (ETDEWEB)

Baieetto, Vanessa E-mail: crpaa@montaigne.u-bordeaux.fr; Villeneuve, Gerard; Guibert, Pierre; Schvoerer, Max

2000-02-01

Thermoluminescence of white powdered marble samples, chosen to display different EPR spectra, were studied. Two peaks at 280 deg. C and 360 deg. C can be observed among the TL glow curves while the EPR spectra exhibit two signals: the A signal with g{sub perp}=2.0038 and g{sub par} =2.0024 due to the SO{sup -}{sub 3} centre and the B one with g{sub 1}=2.0005; g{sub 2}=2.0001; g{sub 3}=1.9998 due to mechanical powder reduction (drilling). Owing to heating and simultaneous experiments, a correlation have been established: the 280 deg. C TL peak is associated to the A signal and thus to the SO{sup -}{sub 3} centre and the 360 deg. C TL peak is caused by mechanical treatment corresponding to the B EPR signal.

EPR: how subtle is the Lord and how is the Lord subtle?

Science.gov (United States)

Plotnitsky, Arkady

The article offers a counterargument to the argument of A. Einstein, B. Podolsky and N. Rosen (EPR) concerning the incompleteness, or else nonlocality, of quantum mechanics, based on Bohr's reply to EPR's article. The article also relates argument to the impossibility of exact repetition of quantum events.

EPR investigation of some traditional oriental irradiated spices

International Nuclear Information System (INIS)

Duliu, Octavian G.; Georgescu, Rodica; Ali, Shaban Ibrahim

2007-01-01

The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and 60 Co γ-ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), and saffron (Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After γ-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 o C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage at room temperature but after 340 days storage at ambient conditions only irradiated ginger displays a weak signal that differs from those of unirradiated sample. All these factors could be taken into account in establishing at which extent the EPR is suitable to evidence any irradiation treatment applied to these spices

EPR investigation of some irradiated traditional oriental spices

International Nuclear Information System (INIS)

Duliu, Octavian G.; Ali, Ibrahim Shaban; Georgescu, Rodica

2005-01-01

The X-band EPR spectra of unirradiated and 60 Co gamma ray irradiated cardamom (Elettaria cardamomum L. Maton, Zingiberaceae), ginger ((Zingiber officinale Rosc., Zingiberaceae), saffron (Crocus sativus L., Iridaceae), and curry have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones, most probably due to the presence of semiquinones, previously reported to have paramagnetic properties. After gamma ray irradiation at absorbed dose up to 11.3 kGy we have noticed in all spices the presence of complex EPR spectra consisting of a superposition of at last two different paramagnetic species whose amplitude increase monotonously with the absorbed dose. A 100 deg. C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that form the initial spectra, but even after 5 h of thermal treatment, the remaining amplitude represents no less than 40% from the initial ones, testifying for a good thermal stability. The presences of initial EPR spectra as well as the remaining amplitude after isothermal annealing are very useful in identifying any irradiation treatment applied to this category of species. (authors)

EPR investigation of some traditional oriental irradiated spices

Science.gov (United States)

Duliu, Octavian G.; Georgescu, Rodica; Ali, Shaban Ibrahim

2007-06-01

The 9.50 GHz electron paramagnetic resonance (EPR) spectra of unirradiated and 60Co γ-ray irradiated cardamom ( Elettaria cardamomum L. Maton, Zingiberaceae), ginger (( Zingiber officinale Rosc., Zingiberaceae), and saffron ( Crocus sativus L., Iridaceae) have been investigated at room temperature. All unirradiated spices presented a weak resonance line with g-factors around free-electron ones. After γ-ray irradiation at an absorbed dose of up to 11.3 kGy, the presence of EPR spectra whose amplitude increase monotonously with the absorbed dose has been noticed with all spices. A 100 °C isothermal annealing of 11.3 kGy irradiated samples has shown a differential reduction of amplitude of various components that compose initial spectra, but even after 3.6 h of thermal treatment, the remaining amplitude represents no less then 30% of the initial ones. The same peculiarities have been noticed after 83 days storage at room temperature but after 340 days storage at ambient conditions only irradiated ginger displays a weak signal that differs from those of unirradiated sample. All these factors could be taken into account in establishing at which extent the EPR is suitable to evidence any irradiation treatment applied to these spices.

High-frequency EPR of surface impurities on nanodiamond

Science.gov (United States)

Peng, Zaili; Stepanov, Viktor; Takahashi, Susumu

Diamond is a fascinating material, hosting nitrogen-vacancy (NV) defect centers with unique magnetic and optical properties. There have been many reports that suggest the existence of paramagnetic impurities near surface of various kinds of diamonds. Electron paramagnetic resonance (EPR) investigation of mechanically crushed nanodiamonds (NDs) as well as detonation NDs revealed g 2 like signals that are attributed to structural defects and dangling bonds near the diamond surface. In this presentation, we investigate paramagnetic impurities in various sizes of NDs using high-frequency (HF) continuous wave (cw) and pulsed EPR spectroscopy. Strong size dependence on the linewidth of HF cw EPR spectra reveals the existence of paramagnetic impurities in the vicinity of the diamond surface. We also study the size dependence of the spin-lattice and spin-spin relaxation times (T1 and T2) of single substitutional nitrogen defects in NDs Significant deviations from the temperature dependence of the phonon-assisted T1 process were observed in the ND samples, and were attributed to the contribution from the surface impurities. This work was supported by the Searle Scholars Program and the National Science Foundation (DMR-1508661 and CHE-1611134).

EPR correlations and EPW distributions

International Nuclear Information System (INIS)

Bell, J.S.

1995-01-01

In the case of two free spin-zero particles, the wave function originally considered by Einstein, Podolsky and Rosen to exemplify EPR correlations has a non-negative Wigner distribution. This distribution gives an explicitly local account of the correlations. For an irreducible non-locality, more elaborate wave functions are required, with Wigner distributions which are not non-negative. (author)

EPR, kvantemekanik og Bohr

OpenAIRE

Nielsen, Morten Klockmann

2007-01-01

Dette projekt omhandler området hvor filosofi og fysik smelter sammen. Kvantemekanikkens tilblivelse fik en hård medfart hvilket diskussionerne mellem især Albert Einstein og Niels Bohr vidner om. De var hovedpersoner i striden om hvordan kvantemekanikken skulle fortolkes, og diskussionen kulminerede i 1935 hvor Einstein sammen med kollegerne Podolsky og Rosen offentliggjorde en artikel med titlen “Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?” (EPR-artiklen)....

Real-time monitoring of drug-induced changes in the stomach acidity of living rats using improved pH-sensitive nitroxides and low-field EPR techniques

Science.gov (United States)

Potapenko, Dmitrii I.; Foster, Margaret A.; Lurie, David J.; Kirilyuk, Igor A.; Hutchison, James M. S.; Grigor'ev, Igor A.; Bagryanskaya, Elena G.; Khramtsov, Valery V.

2006-09-01

New improved pH-sensitive nitroxides were applied for in vivo studies. An increased stability of the probes towards reduction was achieved by the introduction of the bulky ethyl groups in the vicinity of the paramagnetic N sbnd O fragment. In addition, the range of pH sensitivity of the approach was extended by the synthesis of probes with two ionizable groups, and, therefore, with two p Ka values. Stability towards reduction and spectral characteristics of the three new probes were determined in vitro using 290 MHz radiofrequency (RF)- and X-band electron paramagnetic resonance (EPR), longitudinally detected EPR (LODEPR), and field-cycled dynamic nuclear polarization (FC-DNP) techniques. The newly synthesized probe, 4-[bis(2-hydroxyethyl)amino]-2-pyridine-4-yl-2,5,5-triethyl-2,5-dihydro-1 H-imidazol-oxyl, was found to be the most appropriate for the application in the stomach due to both higher stability and convenient pH sensitivity range from pH 1.8 to 6. LODEPR, FC-DNP and proton-electron double resonance imaging (PEDRI) techniques were used to detect the nitroxide localization and acidity in the rat stomach. Improved probe characteristics allowed us to follow in vivo the drug-induced perturbation in the stomach acidity and its normalization afterwards during 1 h or longer period of time. The results show the applicability of the techniques for monitoring drug pharmacology and disease in the living animals.

Active or passive systems? The EPR approach

International Nuclear Information System (INIS)

Bonhomme, N.; Py, J.P.

1996-01-01

In attempting to review how EPR is contemplated to meet requirements applicable to future nuclear power plants, the authors indicate where they see the markets and the corresponding unit sizes for the EPR which is a generic key factor for competitiveness. There are no reason in industrialized countries, other than USA (where the investment and amortizing practices under control by Public Utility Commission are quite particular), not to build future plants in the 1000 to 1500 MWe range. Standardization, which has been actively applied all along the French program and for the Konvoi plants, does not prevent evolution and allows to concentrate large engineering effort in smooth realization of plants and achieve actual construction and commissioning without significant delays. In order to contribute to public trust renewal, a next generation of power reactors should be fundamentally less likely to incur serious accidents. To reach this goal the best of passive and active systems must be considered without forgetting that the most important source of knowledge is construction and operating experience. Criteria to assess passive systems investigated for possible implementation in the EPR, such as simplicity of design, impact on plant operation, safety and cost, are discussed. Examples of the principal passive systems investigated are described and reasons why they have been dropped after screening through the criteria are given. (author). 11 figs

Active or passive systems? The EPR approach

Energy Technology Data Exchange (ETDEWEB)

Bonhomme, N [Nuclear Power International, Cedex (France); Py, J P [FRAMATOME, Cedex (France)

1996-12-01

In attempting to review how EPR is contemplated to meet requirements applicable to future nuclear power plants, the authors indicate where they see the markets and the corresponding unit sizes for the EPR which is a generic key factor for competitiveness. There are no reason in industrialized countries, other than USA (where the investment and amortizing practices under control by Public Utility Commission are quite particular), not to build future plants in the 1000 to 1500 MWe range. Standardization, which has been actively applied all along the French program and for the Konvoi plants, does not prevent evolution and allows to concentrate large engineering effort in smooth realization of plants and achieve actual construction and commissioning without significant delays. In order to contribute to public trust renewal, a next generation of power reactors should be fundamentally less likely to incur serious accidents. To reach this goal the best of passive and active systems must be considered without forgetting that the most important source of knowledge is construction and operating experience. Criteria to assess passive systems investigated for possible implementation in the EPR, such as simplicity of design, impact on plant operation, safety and cost, are discussed. Examples of the principal passive systems investigated are described and reasons why they have been dropped after screening through the criteria are given. (author). 11 figs.

Design and testing of a 750 MHz CW-EPR digital console for small animal imaging

Science.gov (United States)

Sato-Akaba, Hideo; Emoto, Miho C.; Hirata, Hiroshi; Fujii, Hirotada G.

2017-11-01

This paper describes the development of a digital console for three-dimensional (3D) continuous wave electron paramagnetic resonance (CW-EPR) imaging of a small animal to improve the signal-to-noise ratio and lower the cost of the EPR imaging system. A RF generation board, an RF acquisition board and a digital signal processing (DSP) & control board were built for the digital EPR detection. Direct sampling of the reflected RF signal from a resonator (approximately 750 MHz), which contains the EPR signal, was carried out using a band-pass subsampling method. A direct automatic control system to reduce the reflection from the resonator was proposed and implemented in the digital EPR detection scheme. All DSP tasks were carried out in field programmable gate array ICs. In vivo 3D imaging of nitroxyl radicals in a mouse's head was successfully performed.

Nanosecond time-resolved EPR in pulse radiolysis via the spin echo method

International Nuclear Information System (INIS)

Trifunac, A.D.; Norris, J.R.; Lawler, R.G.

1979-01-01

The design and operation of a time-resolved electron spin echo spectrometer suitable for detecting transient radicals produced by 3 MeV electron radiolysis is described. Two modes of operation are available: Field swept mode which generates a normal EPR spectrum and kinetic mode in which the time dependence of a single EPR line is monitored. Techniques which may be used to minimize the effects of nonideal microwave pulses and overlapping sample tube signals are described. The principal advantages of the spin echo method over other time-resolved EPR methods are: (1) Improved time resolution (presently approx.30--50 nsec) allows monitoring of fast changes in EPR signals of transient radicals, (2) Lower susceptibility to interference between the EPR signal and the electron beam pulse at short times, and (3) Lack of dependence of transient signals on microwave field amplitude or static field inhomogeneity at short times. The performance of the instrument is illustrated using CIDEP from acetate radical formed in pulsed radiolysis of aqueous solutions of potassium acetate. The relaxation time and CIDEP enhancement factor obtained for this radical using the spin echo method compare favorably with previous determinations using direct detection EPR. Radical decay rates yield estimates of initial radical concentrations of 10 -4 10 -3 M per electron pulse. The Bloch equations are solved to give an expression for the echo signal for samples exhibiting CIDEP using arbitrary microwave pulse widths and distributions of Larmor frequencies. Conditions are discussed under which the time-dependent signal would be distorted by deviations from an ideal nonselective 90 0 --tau--180 0 pulse sequence

Pulsed EPR analysis of tooth enamel samples exposed to UV and {gamma}-radiations

Energy Technology Data Exchange (ETDEWEB)

Marrale, M., E-mail: marrale@unipa.it [Dipartimento di Fisica, Universita di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN, Catania, Italy and Unita CNISM, Palermo (Italy); Longo, A.; Brai, M. [Dipartimento di Fisica, Universita di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN, Catania (Italy) and Unita CNISM, Palermo (Italy); Barbon, A.; Brustolon, M. [Dipartimento di Scienze Chimiche, Universita degli Studi di Padova, Via Marzolo 1, 35131 Padova (Italy); Fattibene, P. [Istituto Superiore di Sanita, Viale Regina Elena 299, 00161 Rome (Italy)

2011-09-15

The electron paramagnetic resonance (EPR) spectroscopy is widely applied for retrospective dosimetric purposes by means of quantitative detection of radicals in tooth enamel and bone samples. In this work we report a study by cw and pulsed EPR on two samples of human tooth enamel respectively irradiated by UV (254 nm) and {gamma}-exposed. The continuous wave (cw) EPR spectra have shown the usual presence in both samples of two types of CO{sub 2}{sup -} radicals, with axial and orthorombic g tensors. We have obtained the electron spin echo detected EPR (ED-EPR) spectra at 80 K of the two samples, and we have shown that they are suitable to mark the difference between the effects produced by the different irradiations. At low temperature the contribution to the ED-EPR spectrum of the mobile radical with the axial g tensor is still present in the UV irradiated sample, but not in the {gamma}-irradiated one, where its dynamics is too slow to average the g tensor. We have moreover studied the two-pulse electron spin echo decay on varying the microwave power, a well established method for measuring the Instantaneous Diffusion. We have found that the spectral diffusion parameter is almost the same for both radiation types, whereas the Instantaneous Diffusion is significantly larger for {gamma}-exposed samples than for UV irradiated ones. This difference is due to a higher local microscopic concentration of free radicals for samples irradiated with {gamma} photons.

Regularized tripartite continuous variable EPR-type states with Wigner functions and CHSH violations

International Nuclear Information System (INIS)

Jacobsen, Sol H; Jarvis, P D

2008-01-01

We consider tripartite entangled states for continuous variable systems of EPR type, which generalize the famous bipartite CV EPR states (eigenvectors of conjugate choices X 1 - X 2 , P 1 + P 2 , of the systems' relative position and total momentum variables). We give the regularized forms of such tripartite EPR states in second-quantized formulation, and derive their Wigner functions. This is directly compared with the established NOPA-like states from quantum optics. Whereas the multipartite entangled states of NOPA type have singular Wigner functions in the limit of large squeezing, r → ∞, or tanh r → 1 - (approaching the EPR states in the bipartite case), our regularized tripartite EPR states show singular behaviour not only in the approach to the EPR-type region (s → 1 in our notation), but also for an additional, auxiliary regime of the regulator (s→√2). While the s → 1 limit pertains to tripartite CV states with singular eigenstates of the relative coordinates and remaining squeezed in the total momentum, the (s→√2) limit yields singular eigenstates of the total momentum, but squeezed in the relative coordinates. Regarded as expectation values of displaced parity measurements, the tripartite Wigner functions provide the ingredients for generalized CHSH inequalities. Violations of the tripartite CHSH bound (B 3 ≤ 2) are established, with B 3 ≅2.09 in the canonical regime (s → 1 + ), as well as B 3 ≅2.32 in the auxiliary regime (s→√2 + )

Optimization of bicelle lipid composition and temperature for EPR spectroscopy of aligned membranes.

Science.gov (United States)

McCaffrey, Jesse E; James, Zachary M; Thomas, David D

2015-01-01

We have optimized the magnetic alignment of phospholipid bilayered micelles (bicelles) for EPR spectroscopy, by varying lipid composition and temperature. Bicelles have been extensively used in NMR spectroscopy for several decades, in order to obtain aligned samples in a near-native membrane environment and take advantage of the intrinsic sensitivity of magnetic resonance to molecular orientation. Recently, bicelles have also seen increasing use in EPR, which offers superior sensitivity and orientational resolution. However, the low magnetic field strength (less than 1 T) of most conventional EPR spectrometers results in homogeneously oriented bicelles only at a temperature well above physiological. To optimize bicelle composition for magnetic alignment at reduced temperature, we prepared bicelles containing varying ratios of saturated (DMPC) and unsaturated (POPC) phospholipids, using EPR spectra of a spin-labeled fatty acid to assess alignment as a function of lipid composition and temperature. Spectral analysis showed that bicelles containing an equimolar mixture of DMPC and POPC homogeneously align at 298 K, 20 K lower than conventional DMPC-only bicelles. It is now possible to perform EPR studies of membrane protein structure and dynamics in well-aligned bicelles at physiological temperatures and below. Copyright © 2014 Elsevier Inc. All rights reserved.

Light induced electrical and macroscopic changes in hydrogenated polymorphous silicon solar cells

Directory of Open Access Journals (Sweden)

Roca i Cabarrocas P.

2012-07-01

Full Text Available We report on light-induced electrical and macroscopic changes in hydrogenated polymorphous silicon (pm-Si:H PIN solar cells. To explain the particular light-soaking behavior of such cells – namely an increase of the open circuit voltage (Voc and a rapid drop of the short circuit current density (Jsc – we correlate these effects to changes in hydrogen incorporation and structural properties in the layers of the cells. Numerous techniques such as current-voltage characteristics, infrared spectroscopy, hydrogen exodiffusion, Raman spectroscopy, atomic force microscopy, scanning electron microscopy and spectroscopic ellipsometry are used to study the light-induced changes from microscopic to macroscopic scales (up to tens of microns. Such comprehensive use of complementary techniques lead us to suggest that light-soaking produces the diffusion of molecular hydrogen, hydrogen accumulation at p-layer/substrate interface and localized delamination of the interface. Based on these results we propose that light-induced degradation of PIN solar cells has to be addressed from not only as a material issue, but also a device point of view. In particular we bring experimental evidence that localized delamination at the interface between the p-layer and SnO2 substrate by light-induced hydrogen motion causes the rapid drop of Jsc.

CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: Solving a lineshape paradox

Science.gov (United States)

Delpoux, Olivier; Gourier, Didier; Binet, Laurent; Vezin, Hervé; Derenne, Sylvie; Robert, François

2008-05-01

Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4 × 10 19 spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S = 1/2, and centres with S = 0 ground state and thermally accessible triple state S = 1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and 13C nuclei indicates that IOM rad centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H ≈ 1.5 ± 0.5 × 10 -2 of the order of values existing in interstellar medium.

CW- and pulsed-EPR of carbonaceous matter in primitive meteorites: solving a lineshape paradox.

Science.gov (United States)

Delpoux, Olivier; Gourier, Didier; Binet, Laurent; Vezin, Hervé; Derenne, Sylvie; Robert, François

2008-05-01

Insoluble organic matter (IOM) of Orgueil and Tagish Lake meteorites are studied by CW-EPR and pulsed-EPR spectroscopies. The EPR line is due to polycyclic paramagnetic moieties concentrated in defect-rich regions of the IOM, with concentrations of the order of 4x10(19) spin/g. CW-EPR reveals two types of paramagnetic defects: centres with S=1/2, and centres with S=0 ground state and thermally accessible triple state S=1. In spite of the Lorentzian shape of the EPR and its narrowing upon increasing the spin concentration, the EPR line is not in the exchange narrowing regime as previously deduced from multi-frequency CW-EPR [L. Binet, D. Gourier, Appl. Magn. Reson. 30 (2006) 207-231]. It is inhomogeneously broadened as demonstrated by the presence of nuclear modulations in the spin-echo decay. The line narrowing, similar to an exchange narrowing effect, is the result of an increasing contribution of the narrow line of the triplet state centres in addition to the broader line of doublet states. Hyperfine sublevel correlation spectroscopy (HYSCORE) of hydrogen and (13)C nuclei indicates that IOM* centres are small polycyclic moieties that are moderately branched with aliphatic chains, as shown by the presence of aromatic hydrogen atoms. On the contrary the lack of such aromatic hydrogen in triplet states suggests that these radicals are most probably highly branched. Paramagnetic centres are considerably enriched in deuterium, with D/H approximately 1.5+/-0.5x10(-2) of the order of values existing in interstellar medium.

High field high frequency EPR techniques and their application to single molecule magnets

International Nuclear Information System (INIS)

Edwards, R.S.; Hill, S.; Goy, P.; Wylde, R.; Takahashi, S.

2004-01-01

We present details of a new high-field/high-frequency EPR technique, and its application to measurements of single-molecule magnets (SMMs). By using a quasi-optical set-up and microwave sources covering a continuous frequency range from 170 to 600 GHz, in conjunction with a millimetre-wave vector network analyser, we are able to measure EPR to high magnetic fields. For example, a g=2 system will exhibit EPR at about 14 T at a frequency of 400 GHz. We illustrate the technique by presenting details of recent high-frequency experiments on several SMMs which are variations of the well-known SMM Mn 12 -Ac. This material has a spin ground state of S=10 and large uniaxial anisotropy, hence frequencies above 300 GHz are required in order to observe EPR from the ground state

EPR meets the next generation PWR safety requirements

International Nuclear Information System (INIS)

Bouteille, Francois; Czech, Juergen; Sloan, Sandra

2006-01-01

At the origin was the common decision in 1989 of Framatome and Siemens to cooperate to design a Nuclear Island which meets the future needs of utilities. EDF and a group of main German Utilities joined this effort in 1991 and from that point were completely involved in the progress of the work. Compliance of the EPR with the European Utility Requirements (EUR) was verified to ensure a large acceptability of the design by other participating utilities. In addition, the entire process was backed up to the end of 1998 by the French and the German Safety Authorities which engaged into a long-lasting cooperation to define common requirements applicable to future Nuclear Power Plants. Upon signature of the Olkiluoto 3 contract, STUK, the Finnish safety and radiation authority, began reviewing the design of the EPR. Upon the favorable recommendation of STUK, the Finnish government delivered a Construction License for the Olkiluoto 3 NPP on February 17, 2005. Following the positive conclusion of the political debate in France with regard to nuclear energy, EDF will also submit a request to start the construction of an EPR on the Flamanville site. In the US, the first steps in view of a Design Certification by the NRC have been taken. These three independent decisions make the EPR the leading first generation 3+ design under construction. Important safety functions are assured by separate systems in a straightforward operating mode. Four separate, redundant trains for all safety systems are installed in four separate layout division for which a strict separation is ensured so that common mode failure, for example due to internal hazards, can be ruled out. A reduction in common mode failure potential is also obtained by design rules ensuring the systematic application of functional diversity. A four train-redundancy for the major safety systems provides flexibility in adapting the design to maintenance requirements, thus contributing to reduce the outage duration. Additional

All-atom molecular dynamics simulations of spin labelled double and single-strand DNA for EPR studies.

Science.gov (United States)

Prior, C; Danilāne, L; Oganesyan, V S

2018-05-16

We report the first application of fully atomistic molecular dynamics (MD) simulations to the prediction of electron paramagnetic resonance (EPR) spectra of spin labelled DNA. Models for two structurally different DNA spin probes with either the rigid or flexible position of the nitroxide group in the base pair, employed in experimental studies previously, have been developed. By the application of the combined MD-EPR simulation methodology we aimed at the following. Firstly, to provide a test bed against a sensitive spectroscopic technique for the recently developed improved version of the parmbsc1 force field for MD modelling of DNA. The predicted EPR spectra show good agreement with the experimental ones available from the literature, thus confirming the accuracy of the currently employed DNA force fields. Secondly, to provide a quantitative interpretation of the motional contributions into the dynamics of spin probes in both duplex and single-strand DNA fragments and to analyse their perturbing effects on the local DNA structure. Finally, a combination of MD and EPR allowed us to test the validity of the application of the Model-Free (M-F) approach coupled with the partial averaging of magnetic tensors to the simulation of EPR spectra of DNA systems by comparing the resultant EPR spectra with those simulated directly from MD trajectories. The advantage of the M-F based EPR simulation approach over the direct propagation techniques is that it requires motional and order parameters that can be calculated from shorter MD trajectories. The reported MD-EPR methodology is transferable to the prediction and interpretation of EPR spectra of higher order DNA structures with novel types of spin labels.

BCL::MP-Fold: membrane protein structure prediction guided by EPR restraints

Science.gov (United States)

Fischer, Axel W.; Alexander, Nathan S.; Woetzel, Nils; Karakaş, Mert; Weiner, Brian E.; Meiler, Jens

2016-01-01

For many membrane proteins, the determination of their topology remains a challenge for methods like X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy. Electron paramagnetic resonance (EPR) spectroscopy has evolved as an alternative technique to study structure and dynamics of membrane proteins. The present study demonstrates the feasibility of membrane protein topology determination using limited EPR distance and accessibility measurements. The BCL::MP-Fold algorithm assembles secondary structure elements (SSEs) in the membrane using a Monte Carlo Metropolis (MCM) approach. Sampled models are evaluated using knowledge-based potential functions and agreement with the EPR data and a knowledge-based energy function. Twenty-nine membrane proteins of up to 696 residues are used to test the algorithm. The protein-size-normalized root-mean-square-deviation (RMSD100) value of the most accurate model is better than 8 Å for twenty-seven, better than 6 Å for twenty-two, and better than 4 Å for fifteen out of twenty-nine proteins, demonstrating the algorithm’s ability to sample the native topology. The average enrichment could be improved from 1.3 to 2.5, showing the improved discrimination power by using EPR data. PMID:25820805

Multisite EPR oximetry from multiple quadrature harmonics.

Science.gov (United States)

Ahmad, R; Som, S; Johnson, D H; Zweier, J L; Kuppusamy, P; Potter, L C

2012-01-01

Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3-fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. Copyright © 2011 Elsevier Inc. All rights reserved.

EPR application in medicine and biology

Czech Academy of Sciences Publication Activity Database

Stopka, Pavel; Křížová, Jana; Káfuňková, Eva

2005-01-01

Roč. 99, č. 14 (2005), s. 190-192 ISSN 0009-2770 R&D Projects: GA MZd(CZ) NB7377; GA MZd(CZ) NL7567 Institutional research plan: CEZ:AV0Z40320502 Keywords : EPR application Subject RIV: CA - Inorganic Chemistry Impact factor: 0.445, year: 2005

EPR researches of tree cuts for estimating radio - ecological situation

International Nuclear Information System (INIS)

Bitenbayev, M.I.; Polyakov, A.I.

2007-01-01

Full text: The basic aim of present work is to study a possibility of nature object application, in this case the annual rings of trees, for reveal of the effects of post - radiation action for them by EPR method. The cuts of poplars at the age 70 years and older grown in various regions of Kazakhstan with increased level of radiation background were selected as the research objects. EPR spectra were registered for every annual ring separately at the room temperatures. On the basis of EPR experimental results it was ascertained that the EPR spectra of annual rings may be symbolically divided for two groups every of which is possessed of its own definite kind of the spectrum. The first group are the spectra of the annual rings relating to 1981 - 1999 years (in 1999 the trees were cut), and the second group are these of the rings relating 1934 - 1980 years. At that it has been showed that an additional exposure to γ-ray of Co 60 transforms the first group spectrum to the form typical for the second group, i.e. the radiation effect becomes apparent in these experiments. The analyses of EPR spectra parameters has been performed and a correlation between the dependences of intensity of certain components in the spectrum on gamma - irradiation dose and the age of the annul rings has been showed. One can suppose that the intensity changing of these spectrum components in the second group, concerned with free radical accumulation, was the results of long-term action to the object by ionizing radiations. The studied effects can be used for average estimation of absorbed doses of ionizing radiation by environment objects, in particular, by residents of regions surveyed

Measurable difference in Cherenkov light between gamma and hadron induced EAS

Energy Technology Data Exchange (ETDEWEB)

Cabot, H.; Meynadier, Ch. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France); Sobczynska, D. [Experimental Physics Department, University of Lodz, Lodz (Poland); Szabelska, B. [Soltan Institute for Nuclear Studies, Lodz (Poland); Szabelski, J. [Universite de Perpignan, Groupe de Physique Fondamentale, Perpignan (France)]|[Soltan Institute for Nuclear Studies, Lodz (Poland); Wibig, T. [Experimental Physics Department, University of Lodz, Lodz (Poland)

1997-12-31

We describe the possibly measurable difference in the Cherenkov light component of EAS induced by en electromagnetic particle (i.e. e{sup +}, e{sup -} or {gamma}) and induced by a hadron (i.e. proton or heavier nuclei) in TeV range. The method can be applied in experiments which use wavefront sampling method of EAS Cherenkov light detection (e.g. THEMISTOCLE, ASGAT). (author) 16 refs, 9 figs

Advances in Probes and Methods for Clinical EPR Oximetry

Science.gov (United States)

Hou, Huagang; Khan, Nadeem; Jarvis, Lesley A.; Chen, Eunice Y.; Williams, Benjamin B.; Kuppusamy, Periannan

2015-01-01

EPR oximetry, which enables reliable, accurate, and repeated measurements of the partial pressure of oxygen in tissues, provides a unique opportunity to investigate the role of oxygen in the pathogenesis and treatment of several diseases including cancer, stroke, and heart failure. Building on significant advances in the in vivo application of EPR oximetry for small animal models of disease, we are developing suitable probes and instrumentation required for use in human subjects. Our laboratory has established the feasibility of clinical EPR oximetry in cancer patients using India ink, the only material presently approved for clinical use. We now are developing the next generation of probes, which are both superior in terms of oxygen sensitivity and biocompatibility including an excellent safety profile for use in humans. Further advances include the development of implantable oxygen sensors linked to an external coupling loop for measurements of deep-tissue oxygenations at any depth, overcoming the current limitation of 10 mm. This paper presents an overview of recent developments in our ability to make meaningful measurements of oxygen partial pressures in human subjects under clinical settings. PMID:24729217

Development of fire protection standards for the EPR project

International Nuclear Information System (INIS)

Frank, H.J.; Kaercher, M.; Wittmann, R.

2000-01-01

In 1989 Framatome and Siemens decided by setting up their joint subsidiary NPI (Nuclear Power International) to co-operate in designing a new European Pressurised Water Reactor, the EPR. French and German utilities decided to participate in this project. In parallel to the co-operation on supplier's and utility's side, the French and German safety authorities and safety experts wanted to work closely together in order to harmonise and further develop the outstanding safety standards in France and Germany. An organisation has been set up to elaborate common codes related to the EPR design, at the level of the French design and construction rules (RCC) of the German KTA safety standards and DIN standards for nuclear technology, the so-called EPR technical codes (ETC). In this context the decision was made to develop a new fire protection code, the ETC-F, which should be harmonised between France and Germany. The article gives an insight in the developing process of the ETC-F and an outlook on existing and perhaps further national activities. (orig.) [de

Design and testing of a 750MHz CW-EPR digital console for small animal imaging.

Science.gov (United States)

Sato-Akaba, Hideo; Emoto, Miho C; Hirata, Hiroshi; Fujii, Hirotada G

2017-11-01

This paper describes the development of a digital console for three-dimensional (3D) continuous wave electron paramagnetic resonance (CW-EPR) imaging of a small animal to improve the signal-to-noise ratio and lower the cost of the EPR imaging system. A RF generation board, an RF acquisition board and a digital signal processing (DSP) & control board were built for the digital EPR detection. Direct sampling of the reflected RF signal from a resonator (approximately 750MHz), which contains the EPR signal, was carried out using a band-pass subsampling method. A direct automatic control system to reduce the reflection from the resonator was proposed and implemented in the digital EPR detection scheme. All DSP tasks were carried out in field programmable gate array ICs. In vivo 3D imaging of nitroxyl radicals in a mouse's head was successfully performed. Copyright © 2017 Elsevier Inc. All rights reserved.

EPR a strategic choice

International Nuclear Information System (INIS)

2003-01-01

How can we answer to the increasing demand of electric power, resulting of the demographic evolution and needed to the economic development, without exhausting the fossil resources? The answers are function of the countries and imply an optimization of the production and the consumption. This document published by the Areva Group aims to show the advantages of the nuclear energy: economical and environmental advantages. A special chapter is devoted to the European Pressurized Reactor, EPR. (A.L.B.)

Membrane remodeling by amyloidogenic and non-amyloidogenic proteins studied by EPR.

Science.gov (United States)

Varkey, Jobin; Langen, Ralf

2017-07-01

The advancement in site-directed spin labeling of proteins has enabled EPR studies to expand into newer research areas within the umbrella of protein-membrane interactions. Recently, membrane remodeling by amyloidogenic and non-amyloidogenic proteins has gained a substantial interest in relation to driving and controlling vital cellular processes such as endocytosis, exocytosis, shaping of organelles like endoplasmic reticulum, Golgi and mitochondria, intracellular vesicular trafficking, formation of filopedia and multivesicular bodies, mitochondrial fusion and fission, and synaptic vesicle fusion and recycling in neurotransmission. Misregulation in any of these processes due to an aberrant protein (mutation or misfolding) or alteration of lipid metabolism can be detrimental to the cell and cause disease. Dissection of the structural basis of membrane remodeling by proteins is thus quite necessary for an understanding of the underlying mechanisms, but it remains a formidable task due to the difficulties of various common biophysical tools in monitoring the dynamic process of membrane binding and bending by proteins. This is largely since membranes generally complicate protein structure analysis and this problem is amplified for structural analysis in the presence of different types of membrane curvatures. Recent EPR studies on membrane remodeling by proteins show that a significant structural information can be generated to delineate the role of different protein modules, domains and individual amino acids in the generation of membrane curvature. These studies also show how EPR can complement the data obtained by high resolution techniques such as X-ray and NMR. This perspective covers the application of EPR in recent studies for understanding membrane remodeling by amyloidogenic and non-amyloidogenic proteins that is useful for researchers interested in using or complimenting EPR to gain better understanding of membrane remodeling. We also discuss how a single

Membrane remodeling by amyloidogenic and non-amyloidogenic proteins studied by EPR

Science.gov (United States)

Varkey, Jobin; Langen, Ralf

2017-07-01

The advancement in site-directed spin labeling of proteins has enabled EPR studies to expand into newer research areas within the umbrella of protein-membrane interactions. Recently, membrane remodeling by amyloidogenic and non-amyloidogenic proteins has gained a substantial interest in relation to driving and controlling vital cellular processes such as endocytosis, exocytosis, shaping of organelles like endoplasmic reticulum, Golgi and mitochondria, intracellular vesicular trafficking, formation of filopedia and multivesicular bodies, mitochondrial fusion and fission, and synaptic vesicle fusion and recycling in neurotransmission. Misregulation in any of these processes due to an aberrant protein (mutation or misfolding) or alteration of lipid metabolism can be detrimental to the cell and cause disease. Dissection of the structural basis of membrane remodeling by proteins is thus quite necessary for an understanding of the underlying mechanisms, but it remains a formidable task due to the difficulties of various common biophysical tools in monitoring the dynamic process of membrane binding and bending by proteins. This is largely since membranes generally complicate protein structure analysis and this problem is amplified for structural analysis in the presence of different types of membrane curvatures. Recent EPR studies on membrane remodeling by proteins show that a significant structural information can be generated to delineate the role of different protein modules, domains and individual amino acids in the generation of membrane curvature. These studies also show how EPR can complement the data obtained by high resolution techniques such as X-ray and NMR. This perspective covers the application of EPR in recent studies for understanding membrane remodeling by amyloidogenic and non-amyloidogenic proteins that is useful for researchers interested in using or complimenting EPR to gain better understanding of membrane remodeling. We also discuss how a single

Nitroxide free radical clearance in the live rat monitored by radio-frequency CW-EPR and PEDRI

International Nuclear Information System (INIS)

Alecci, Marcello; Seimenis, Ioannis; McCallum, Stephen J.; Lurie, David J.; Foster, Margaret A.

1998-01-01

The use of RF (100 to 300 MHz) PEDRI and CW-EPR techniques allows the in vivo study of large animals such as whole rats and rabbits. Recently a PEDRI instrument was modified to also allow CW-EPR spectroscopy with samples of similar size and under the same experimental conditions. In the present study, this CW-EPR and PEDRI apparatus was used to assess the feasibility of the detection of a pyrrolidine nitroxide free radical (2,2,5,5,-tetramethylpyrrolidine-1-oxyl-3-carboxylic acid, PCA) in the abdomen of rats. In particular, we have shown that after the PCA administration (4 mmol kg -1 b.w.): (i) the PCA EPR linewidth does not show line broadening due to concentration effects; (ii) a similar PCA up-take phase is observed by EPR and PEDRI; and (iii) the PCA half-lives in the whole abdomen of rats measured with the CW-EPR (T 1/2 =26±4 min, mean±sd, n=10) and PEDRI (T 1/2 =29±4 min, mean±sd, n=4) techniques were not significantly different (p>0.05). These results show, for the first time, that information about PCA pharmacokinetics obtained by CW-EPR is the same as that from PEDRI under the same experimental conditions. (author)

Light induced cooling of a heated solid immersed in liquid helium I

International Nuclear Information System (INIS)

Lezak, D.; Brodie, L.C.; Semura, J.S.

1984-01-01

This chapter investigates the marked enhancement in the transient heat transfer from the heater-thermometer to the liquid helium immediately following the application of a flash of visible light. This ''light effect'' is associated with increased bubble activity, and it is possible that the light induces a rapid nucleation of bubbles in the superheated liquid at or near the heater surface. A summary of the light effect is presented and some potential uses to which this effect could be applied are suggested. Quantification of the light effect and properties of the light effect are discussed. It is determined that the light effect is an additional cooling due to a light induced enhancement of boiling in superheated liquid helium I. The effect could be applied in practical cryogenic engineering and for the acquisition of fundamental knowledge of boiling heat transfer and nucleation in cryogenic liquids

75 FR 7633 - Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on EPR; Notice...

Science.gov (United States)

2010-02-22

... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS); Meeting of the ACRS Subcommittee on EPR; Notice of Meeting The ACRS U.S. Evolutionary Power Reactor (EPR) Subcommittee will hold a....S. EPR Design Certification Document Review. The Subcommittee will gather information, analyze...

Studies into the transplantation biology of ultraviolet light-induced tumors

International Nuclear Information System (INIS)

Daynes, R.A.; Spellman, C.W.; Woodward, J.G.; Stewart, D.A.

1977-01-01

The majority of skin tumors induced in mice by ultraviolet (uv) light are rejected when implanted into normal syngeneic recipients. Subcarcinogenic levels of uv light exposure render the normally resistant mice susceptible to tumor challenge. The immunoregulatory effect of uv light appears to be additive, since the growth rate of a tumor transplant is dependent upon the length of uv exposure administered prior to implantation. This suppressive influence does not appear to be directly mediated by the uv light, because the amputation of uv-irradiated tail skin allows for a retention of tumor resistance in otherwise tumor-susceptible hosts. uv-irradiated mice could also be immunized against uv tumors, which suggests that immune recognition of tumor-specific transplantation antigens has not been inhibited. The ability of uv exposure to alter normal immunological reactivity to uv-induced tumors is possibly an integral factor in the mechanism underlying uv carcinogenesis

EPR and optical study of Mn{sup 2+} doped monohydrated dipotassium stannic chloride

Energy Technology Data Exchange (ETDEWEB)

Kripal, Ram, E-mail: ram_kripal2001@rediffmail.com; Singh, Manju

2014-11-15

Highlights: • EPR study of Mn{sup 2+}: DPSC crystal is done at room temperature. • The spin Hamiltonian parameters for two Mn{sup 2+} sites are determined. • The optical absorption study is also done. • The nature of metal–ligand bonding is discussed on the basis of EPR and optical data. • Theoretical zero-field splitting parameters match well with the experimental values. - Abstract: Electron paramagnetic resonance (EPR) study at room temperature (RT) is used to investigate the property of Mn{sup 2+} doped monohydrated dipotassium stannic chloride (K{sub 2}SnCl{sub 4}⋅H{sub 2}O) single crystal. EPR spectra show that there exist two substitutional sites, the spin Hamiltonian parameters for which are determined. The optical absorption study is also done at room temperature in the wavelength range 195–1100 nm. The observed bands are assigned as transitions from {sup 6}A{sub 1g}(S) ground state to various excited states. These bands are fitted with four parameters, namely Racah inter-electronic repulsion parameters B = 792 cm{sup −1}, C = 2278 cm{sup −1}; cubic crystal field splitting parameter Dq = 700 cm{sup −1} and Trees correction α = 76 cm{sup −1}. The nature of metal–ligand bonding is discussed on the basis of EPR and optical data. Superposition model (SPM) is used to find out the crystal field (CF) parameters and the perturbation formulae are used to obtain zero-field splitting (ZFS) parameters. Theoretically calculated ZFS parameters match well with the experimental values obtained from EPR study.

Kinetic study of UV-irradiated amorphous sulfur by EPR spectroscopy

International Nuclear Information System (INIS)

El Mkami, H.; Smith, G.M.

2005-01-01

Electron paramagnetic resonance (EPR) spectroscopy is used to investigate UV-irradiation damage in amorphous sulfur by examining post-irradiation kinetics as a function of UV-exposure time. The kinetic study is described by first-order concurrent reactions where the sulfur, as reactant, undergoes two parallel processes leading to the formation of two distinct defects called S 1 * and S 2 *. The temperature dependence of the EPR intensities of the signals, related to these defects, is used in the kinetic study

A stable blue-light-derived signal modulates ultraviolet-light-induced activation of the chalcone-synthase gene in cultured parsley cells

International Nuclear Information System (INIS)

Ohl, S.; Hahlbrock, K.; Schäfer, E.

1989-01-01

Run-off transcription assays were used to demonstrate that both the ultraviolet (UV)-B and blue-light receptors control transcription rates for chalcone-synthase mRNA in the course of light-induced flavonoid synthesis in parsley (Petroselinum crispum Miller (A.W. Hill)) cell-suspension cultures. Blue and red light alone, presumably acting via a blue-light receptor and active phytochrome (far-red absorbing form) respectively, can induce accumulation of chalcone-synthase mRNA. The extent of the response is however considerably smaller than that obtained when these wavebands are applied in combination with UV light. A preirradiation with blue light strongly increases the response to a subsequent UV pulse and this modulating effect of blue light is stable for at least 20 h. The modulating effect is abolished by a UV induction but can be reestablished by a second irradiation with blue light. (author)

EPR: what has it taught us

International Nuclear Information System (INIS)

Stapp, H.P.

1985-05-01

This symposium commemorating the fiftieth anniversary of the paper of Einstein, Podolsky, and Rosen is a fitting place to review what that work and its sequels have taught us. Prima facie, the EPR paper appears to have been exceedingly counter-productive for the following reasons: (1) The work was quickly rebutted by Bohr, and this rebuttal was apparently accepted by most workers in the field. (2) Scientists who adopted the position advocated by Bohr have produced, in the intervening fifty years, a marvelous body of useful theory, whereas those following the course suggested by EPR have produced nothing of any certified practical value. (3) It has been shown by Bell that the conclusion reached by EPR is incompatible with their assumptions. Chemists and physicists have recently begun to examine the behavior of quantum mechanical systems that are very small, yet large enough to influence their environment in ways that appreciably modify their own behavior, vis-a-vis the behavior they would have if isolated. Because these systems are neither small enough to be treated as isolated (or as residing in a classically described environment) between preparation and detection, nor large enough to be treated classically, they do not conform to the format demanded by the Copenhagen interpretation. Indeed, the behavior of these systems depends on ontological considerations that were irrelevant in the situations covered by the Copenhagen interpretation, and that were systematically ignored in that interpretation. Scientists now face the task of enlarging the scope of quantum theory to cover these new situations, and comparing the empirical consequences of various ontological assumptions. 17 refs

Fluorescent-light-induced lethality and DNA repair in normal and xeroderma pigmentosum fibroblasts

International Nuclear Information System (INIS)

Ritter, M.A.; Williams, J.R.

1981-01-01

Cell survival and induction of endonuclease-sensitive sites in DNA were measured in human fibroblast cells exposed to fluorescent light or germicidal ultraviolet light. Cells from a xeroderma pigmentosum patient were hypersensitive to cell killing by fluorescent light, although less so than for germicidal ultraviolet light. Xeroderma pigmentosum cells were deficient in the removal of fluorescent light-induced endonuclease sites that are probably pyrimidine dimers, and both the xeroderma pigmentosum and normal cells removed these sites with kinetics indistinguishable from those for ultraviolet light-induced sites. A comparison of fluorescent with ultraviolet light data demonstrates that there are markedly fewer pyrimidine dimers per lethal event for fluorescent than for ultraviolet light, suggesting a major role for non-dimer damage in fluorescent lethality. (Auth.)

High resolution Cerenkov light imaging of induced positron distribution in proton therapy

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Fujii, Kento; Morishita, Yuki; Okumura, Satoshi; Komori, Masataka [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine, Aichi 461-8673 (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center, Aichi 462-8508 (Japan)

2014-11-01

Purpose: In proton therapy, imaging of the positron distribution produced by fragmentation during or soon after proton irradiation is a useful method to monitor the proton range. Although positron emission tomography (PET) is typically used for this imaging, its spatial resolution is limited. Cerenkov light imaging is a new molecular imaging technology that detects the visible photons that are produced from high-speed electrons using a high sensitivity optical camera. Because its inherent spatial resolution is much higher than PET, the authors can measure more precise information of the proton-induced positron distribution with Cerenkov light imaging technology. For this purpose, they conducted Cerenkov light imaging of induced positron distribution in proton therapy. Methods: First, the authors evaluated the spatial resolution of our Cerenkov light imaging system with a {sup 22}Na point source for the actual imaging setup. Then the transparent acrylic phantoms (100 × 100 × 100 mm{sup 3}) were irradiated with two different proton energies using a spot scanning proton therapy system. Cerenkov light imaging of each phantom was conducted using a high sensitivity electron multiplied charge coupled device (EM-CCD) camera. Results: The Cerenkov light’s spatial resolution for the setup was 0.76 ± 0.6 mm FWHM. They obtained high resolution Cerenkov light images of the positron distributions in the phantoms for two different proton energies and made fused images of the reference images and the Cerenkov light images. The depths of the positron distribution in the phantoms from the Cerenkov light images were almost identical to the simulation results. The decay curves derived from the region-of-interests (ROIs) set on the Cerenkov light images revealed that Cerenkov light images can be used for estimating the half-life of the radionuclide components of positrons. Conclusions: High resolution Cerenkov light imaging of proton-induced positron distribution was possible. The