A Novel Method for Remote Depth Estimation of Buried Radioactive Contamination.

PubMed

Ukaegbu, Ikechukwu Kevin; Gamage, Kelum A A

2018-02-08

Existing remote radioactive contamination depth estimation methods for buried radioactive wastes are either limited to less than 2 cm or are based on empirical models that require foreknowledge of the maximum penetrable depth of the contamination. These severely limits their usefulness in some real life subsurface contamination scenarios. Therefore, this work presents a novel remote depth estimation method that is based on an approximate three-dimensional linear attenuation model that exploits the benefits of using multiple measurements obtained from the surface of the material in which the contamination is buried using a radiation detector. Simulation results showed that the proposed method is able to detect the depth of caesium-137 and cobalt-60 contamination buried up to 40 cm in both sand and concrete. Furthermore, results from experiments show that the method is able to detect the depth of caesium-137 contamination buried up to 12 cm in sand. The lower maximum depth recorded in the experiment is due to limitations in the detector and the low activity of the caesium-137 source used. Nevertheless, both results demonstrate the superior capability of the proposed method compared to existing methods.

40K/137Cs discrimination ratios to the aboveground organs of tropical plants.

PubMed

Sanches, N; Anjos, R M; Mosquera, B

2008-07-01

In the present work, the accumulation of caesium and potassium in aboveground plant parts was studied in order to improve the understanding on the behaviour of monovalent cations in several compartments of tropical plants. We present the results for activity concentrations of (137)Cs and (40)K, measured by gamma spectrometry, from five tropical plant species: guava (Psidium guajava), mango (Mangifera indica), papaya (Carica papaya), banana (Musa paradisíaca), and manioc (Manihot esculenta). Caesium and potassium have shown a high level of mobility within the plants, exhibiting the highest values of concentration in the growing parts (fruits, leaves, twigs, and barks) of the woody fruit and large herbaceous shrub (such as manioc) species. In contrast, the banana and papaya plants exhibited the lowest levels of (137)Cs and (40)K in their growing parts. However, a significant correlation between activity concentrations of (137)Cs and (40)K was observed in these tropical plants. The (40)K/(137)Cs discrimination ratios were approximately equal to unity in different compartments of each individual plant, suggesting the possibility of using caesium to predict the behaviour of potassium in several tropical species.

A Novel Method for Remote Depth Estimation of Buried Radioactive Contamination

PubMed Central

2018-01-01

Existing remote radioactive contamination depth estimation methods for buried radioactive wastes are either limited to less than 2 cm or are based on empirical models that require foreknowledge of the maximum penetrable depth of the contamination. These severely limits their usefulness in some real life subsurface contamination scenarios. Therefore, this work presents a novel remote depth estimation method that is based on an approximate three-dimensional linear attenuation model that exploits the benefits of using multiple measurements obtained from the surface of the material in which the contamination is buried using a radiation detector. Simulation results showed that the proposed method is able to detect the depth of caesium-137 and cobalt-60 contamination buried up to 40 cm in both sand and concrete. Furthermore, results from experiments show that the method is able to detect the depth of caesium-137 contamination buried up to 12 cm in sand. The lower maximum depth recorded in the experiment is due to limitations in the detector and the low activity of the caesium-137 source used. Nevertheless, both results demonstrate the superior capability of the proposed method compared to existing methods. PMID:29419759

Caesium sputter ion source compatible with commercial SIMS instruments

NASA Astrophysics Data System (ADS)

Belykh, S. F.; Palitsin, V. V.; Veryovkin, I. V.; Kovarsky, A. P.; Chang, R. J. H.; Adriaens, A.; Dowsett, M.; Adams, F.

2006-07-01

A simple design for a caesium sputter cluster ion source compatible with commercially available secondary ion mass spectrometers is reported. This source has been tested with the Cameca IMS 4f instrument using the cluster Si n- and Cu n- ions, and will shortly be retrofitted to the floating low energy ion gun (FLIG) of the type used on the Cameca 4500/4550 quadruple instruments. Our experiments with surface characterization and depth profiling conducted to date demonstrate improvements of analytical capabilities of the SIMS instrument due to the non-additive enhancement of secondary ion emission and shorter ion ranges of polyatomic projectiles compared to atomic ions with the same impact energy.

Micrometer-level naked-eye detection of caesium particulates in the solid state

NASA Astrophysics Data System (ADS)

Mori, Taizo; Akamatsu, Masaaki; Okamoto, Ken; Sumita, Masato; Tateyama, Yoshitaka; Sakai, Hideki; Hill, Jonathan P.; Abe, Masahiko; Ariga, Katsuhiko

2013-02-01

Large amounts of radioactive material were released from the Fukushima Daiichi nuclear plant in Japan, contaminating the local environment. During the early stages of such nuclear accidents, iodine I-131 (half-life 8.02 d) is usually detectable in the surrounding atmosphere and bodies of water. On the other hand, in the long-term, soil and water contamination by Cs-137, which has a half-life of 30.17 years, is a serious problem. In Japan, the government is planning and carrying out radioactive decontamination operations not only with public agencies but also non-governmental organizations, making radiation measurements within Japan. If caesium (also radiocaesium) could be detected by the naked eye then its environmental remediation would be facilitated. Supramolecular material approaches, such as host-guest chemistry, are useful in the design of high-resolution molecular sensors and can be used to convert molecular-recognition processes into optical signals. In this work, we have developed molecular materials (here, phenols) as an optical probe for caesium cation-containing particles with implementation based on simple spray-on reagents and a commonly available fluorescent lamp for naked-eye detection in the solid state. This chemical optical probe provides a higher spatial resolution than existing radioscopes and gamma-ray cameras.

Progress of the ELISE test facility: towards one hour pulses in hydrogen

NASA Astrophysics Data System (ADS)

Wünderlich, D.; Fantz, U.; Heinemann, B.; Kraus, W.; Riedl, R.; Wimmer, C.; the NNBI Team

2016-10-01

In order to fulfil the ITER requirements, the negative hydrogen ion source used for NBI has to deliver a high source performance, i.e. a high extracted negative ion current and simultaneously a low co-extracted electron current over a pulse length up to 1 h. Negative ions will be generated by the surface process in a low-temperature low-pressure hydrogen or deuterium plasma. Therefore, a certain amount of caesium has to be deposited on the plasma grid in order to obtain a low surface work function and consequently a high negative ion production yield. This caesium is re-distributed by the influence of the plasma, resulting in temporal instabilities of the extracted negative ion current and the co-extracted electrons over long pulses. This paper describes experiments performed in hydrogen operation at the half-ITER-size NNBI test facility ELISE in order to develop a caesium conditioning technique for more stable long pulses at an ITER relevant filling pressure of 0.3 Pa. A significant improvement of the long pulse stability is achieved. Together with different plasma diagnostics it is demonstrated that this improvement is correlated to the interplay of very small variations of parameters like the electrostatic potential and the particle densities close to the extraction system.

Estimation of the caesium-137 source term from the Fukushima Daiichi nuclear power plant using a consistent joint assimilation of air concentration and deposition observations

NASA Astrophysics Data System (ADS)

Winiarek, Victor; Bocquet, Marc; Duhanyan, Nora; Roustan, Yelva; Saunier, Olivier; Mathieu, Anne

2014-01-01

Inverse modelling techniques can be used to estimate the amount of radionuclides and the temporal profile of the source term released in the atmosphere during the accident of the Fukushima Daiichi nuclear power plant in March 2011. In Winiarek et al. (2012b), the lower bounds of the caesium-137 and iodine-131 source terms were estimated with such techniques, using activity concentration measurements. The importance of an objective assessment of prior errors (the observation errors and the background errors) was emphasised for a reliable inversion. In such critical context where the meteorological conditions can make the source term partly unobservable and where only a few observations are available, such prior estimation techniques are mandatory, the retrieved source term being very sensitive to this estimation. We propose to extend the use of these techniques to the estimation of prior errors when assimilating observations from several data sets. The aim is to compute an estimate of the caesium-137 source term jointly using all available data about this radionuclide, such as activity concentrations in the air, but also daily fallout measurements and total cumulated fallout measurements. It is crucial to properly and simultaneously estimate the background errors and the prior errors relative to each data set. A proper estimation of prior errors is also a necessary condition to reliably estimate the a posteriori uncertainty of the estimated source term. Using such techniques, we retrieve a total released quantity of caesium-137 in the interval 11.6-19.3 PBq with an estimated standard deviation range of 15-20% depending on the method and the data sets. The “blind” time intervals of the source term have also been strongly mitigated compared to the first estimations with only activity concentration data.

[Contamination of the food chain with caesium-137 and strontium-90 in Switzerland].

PubMed

Riond, J L

2004-12-01

One task of the field physiology of nutrition is the monitoring of the quality of feedstuffs. Rations may consequently be prepared with unadulterated components. This review uses the example of contamination with the radionuclides caesium-137 und strontium-90 and shows how these two unwanted substances reach the end host via the food chain and how their untoward effects are expressed in animals and humans. The extent of the contamination with artificial radioactivity is followed with periodical measurements according to the program of the Division for Radiological Protection of the Swiss Federal Office of Public Health. The interpretation of the measurements and the directives of this division are designed to protect primarily human health, but also that of animals.

Distribution and turnover of (137)Cs in birch forest ecosystems: influence of precipitation chemistry.

PubMed

Thørring, H; Skuterud, L; Steinnes, E

2012-08-01

The aim of the present work was to study radioactive caesium in soil and plants from birch forests subject to different chemical climate. Four areas and three types of precipitation regimes were considered, representing a natural climatic range found in Norway: (A) acidic precipitation (southernmost part of the country); (B) precipitation rich in "sea salts"/marine cations (coastal areas); and (C) + (D) low concentrations of sea salts (inland areas). The results showed significant regional differences in plant uptake between the investigated areas. For instance the aggregated soil-to-plant transfer coefficients (Tag) were generally up to 7-8 times higher for the area receiving acid rain. Differences in caesium speciation partly explained the regional variability - e.g. the exchangeable fraction ranged from 1 to 40% (with the largest fraction of exchangeable caesium found in southernmost Norway). Transfer coefficients estimated on the basis of exchangeable fractions showed no significant differences between the areas of highest (A) and lowest (C) Tags. However, exchangeable fractions taken into consideration, the uptake of (137)Cs in plants in the acid rain-influenced area is still about twice that in the sea salt influenced area B. A significantly lower concentration of soluble base cations and a higher share of acid components in soils in area A is a likely explanation for this observation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Observation of EIA in closed and open caesium atomic system

NASA Astrophysics Data System (ADS)

Zhao, Jian-Ming; Zhao, Yan-Ting; Huang, Tao; Xiao, Lian-Tuan; Jia, Suo-Tang

2005-04-01

We present an experimental study on electromagnetically induced absorption (EIA) in the closed transition of a degenerate two-level Cs atomic system. The coupling and probe lasers coupled with the transition 6S1/2F=4 → 6P3/2F'=5 of caesium atom. The signal of EIA was obtained and the frequency detuning and intensity effect of the pumping laser were experimentally investigated. The EIA signal in 6S1/2 F=4 → 6P3/2 F'=4 and 6S1/2 F=4 → 6P3/2 F'=3 open transitions was also obtained. As the repumping laser couples with the transition of 6S1/2 F=3 → 6P3/2 F'=4, the EIA signal is increased due to the hyperfine optical pumping.

Participation in proficiency test for tritium strontium and caesium isotopes in seawater 2015 (IAEA-RML-2015-02)

NASA Astrophysics Data System (ADS)

Visetpotjanakit, S.; Kaewpaluek, S.

2017-06-01

A proficiency test (PT) exercise has proposed by the International Atomic Energy Agency (IAEA) in the frame of the IAEA Technical Cooperation project RAS/7/021 “Marine benchmark study on the possible impact of the Fukushima radioactive releases in the Asia-Pacific Region for Caesium Determination in Sea Water” since 2012. In 2015 the exercise was referred to Proficiency Test for Tritium, Strontium and Caesium Isotopes in Seawater 2015 (IAEA-RML-2015-02) to analyse3H, 134Cs, 137Cs and90Sr in a seawater sample. OAP was one of the 17 laboratories from 15 countries from Asia-Pacific Region who joined the PT exercise. The aim of our participation was to validate our analytical performance for the accurate determination of radionuclides in seawater by developed methods of radiochemical analysis. OAP submitted results determining the concentration for the three elements i.e. 134Cs, 137Cs and90Sr in seawater to the IAEA. A critical review was made to check suitability of our methodology and the criteria for the accuracy, precision and trueness of our data. The results of both 134Cs and 137Cs passed all criteria which were assigned “Accepted” statuses. Whereas 90Sr analysis did not pass the accuracy test therefore it was considered as “Not accepted” Our results and all other participant results with critical comments were published in the IAEA proficiency test report.

Production of intensive negative lithium beam with caesium sputter-type ion source

NASA Astrophysics Data System (ADS)

Lobanov, Nikolai R.

2018-01-01

Compounds of lithium oxide, hydroxide and carbonate, mixed with silver, were prepared for use as a cathode in caesium-sputter ion source. The intention was to determine the procedure which would produce the highest intensity negative lithium beams over extended period and with maximum stability. The chemical composition and properties of the samples were analysed using mass-spectrometry, optical microscopy, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Analyses (EDX) and Raman spectroscopy. These analyses showed that the chemical transformations with components resulted from pressing, storage and bake out were qualitatively in agreement with expectations. Intensive negative lithium ion beams >1 μA were delivered using cathodes fabricated from materials with multicomponent chemical composition when the following conditions were met: (i) use of components with moderate enthalpy of formation; (ii) low moisture content at final stage of cathode production and (iii) small concentration of water molecules in hydrate phase in the cathode mixture.

High wettability of liquid caesium iodine with solid uranium dioxide.

PubMed

Kurosaki, Ken; Suzuki, Masanori; Uno, Masayoshi; Ishii, Hiroto; Kumagai, Masaya; Anada, Keito; Murakami, Yukihiro; Ohishi, Yuji; Muta, Hiroaki; Tanaka, Toshihiro; Yamanaka, Shinsuke

2017-09-13

In March 2011, the Fukushima Daiichi Nuclear Power Plant accident caused nuclear fuel to melt and the release of high-volatility fission products into the environment. Caesium and iodine caused environmental contamination and public exposure. Certain fission-product behaviours remain unclear. We found experimentally that liquid CsI disperses extremely favourably toward solid UO 2 , exhibiting a contact angle approaching zero. We further observed the presence of CsI several tens of micrometres below the surface of the solid UO 2 sample, which would be caused by the infiltration of pores network by liquid CsI. Thus, volatile fission products released from molten nuclear fuels with complex internal composition and external structure migrate or evaporate to varying extents, depending on the nature of the solid-liquid interface and the fuel material surface, which becomes the pathway for the released fission products. Introducing the concept of the wettability of liquid chemical species of fission products in contact with solid fuels enabled developing accurate behavioural assessments of volatile fission products released by nuclear fuel.

Wiedemann-Franz ratio in high-pressure and low-temperature thermal xenon plasma with 10% caesium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Novakovic, N.V.; Milic, B.S.; Stojilkovic, S.M.

1995-12-31

Theoretical investigations of various transport properties of low-temperature noble-gas plasmas with additives has aroused a continuous interest over a considerable spall of time, due to numerous applications. In this paper the results of a theoretical evaluation of electrical conductivity, thermal conductivity and their ratio (the Wiedemann-Franz ratio) in xenon plasma with 10% of argon and 10% of caesium are presented, for the temperature range from 2000 K to 20000 K, and for pressures equal to or 5, 10, and 15 time higher than the normal atmospheric pressure. The plasma was regarded as weakly non-ideal and in the state of localmore » thermodynamical equilibrium with the assumption that the equilibrium is attained with the pressure kept constant. The plasma composition was determined on the ground of a set of Saha equations; the ionization energy lowerings were expressed with the aid of a modified plasma Debye radius r*{sub D} (rather than the standard r{sub D}), as proposed previously.« less

Rydberg atoms in hollow-core photonic crystal fibres.

PubMed

Epple, G; Kleinbach, K S; Euser, T G; Joly, N Y; Pfau, T; Russell, P St J; Löw, R

2014-06-19

The exceptionally large polarizability of highly excited Rydberg atoms-six orders of magnitude higher than ground-state atoms--makes them of great interest in fields such as quantum optics, quantum computing, quantum simulation and metrology. However, if they are to be used routinely in applications, a major requirement is their integration into technically feasible, miniaturized devices. Here we show that a Rydberg medium based on room temperature caesium vapour can be confined in broadband-guiding kagome-style hollow-core photonic crystal fibres. Three-photon spectroscopy performed on a caesium-filled fibre detects Rydberg states up to a principal quantum number of n=40. Besides small energy-level shifts we observe narrow lines confirming the coherence of the Rydberg excitation. Using different Rydberg states and core diameters we study the influence of confinement within the fibre core after different exposure times. Understanding these effects is essential for the successful future development of novel applications based on integrated room temperature Rydberg systems.

Simultaneous Faraday filtering of the Mollow triplet sidebands with the Cs-D1 clock transition.

PubMed

Portalupi, Simone Luca; Widmann, Matthias; Nawrath, Cornelius; Jetter, Michael; Michler, Peter; Wrachtrup, Jörg; Gerhardt, Ilja

2016-11-25

Hybrid quantum systems integrating semiconductor quantum dots (QDs) and atomic vapours become important building blocks for scalable quantum networks due to the complementary strengths of individual parts. QDs provide on-demand single-photon emission with near-unity indistinguishability comprising unprecedented brightness-while atomic vapour systems provide ultra-precise frequency standards and promise long coherence times for the storage of qubits. Spectral filtering is one of the key components for the successful link between QD photons and atoms. Here we present a tailored Faraday anomalous dispersion optical filter based on the caesium-D 1 transition for interfacing it with a resonantly pumped QD. The presented Faraday filter enables a narrow-bandwidth (Δω=2π × 1 GHz) simultaneous filtering of both Mollow triplet sidebands. This result opens the way to use QDs as sources of single as well as cascaded photons in photonic quantum networks aligned to the primary frequency standard of the caesium clock transition.

Irradiation of members of the general public from radioactive caesium following the Chernobyl reactor accident: Field studies in a highly contaminated area in the Bryansk region, Russia

NASA Astrophysics Data System (ADS)

Thornberg, Charlotte

From 1990 to 1998, estimations of the effective dose due to irradiation from 137Cs and 134Cs were carried out for inhabitants in rural villages in the Bryansk region, Russia. The villages, situated about 180 km from the Chernobyl power plant received deposition of 137Cs in the range 0.9-2.7 MBq m-2 due to the accident in 1986. The body burden of 137,134Cs was estimated from measurements of the urinary concentration of caesium radionuclides, together with in vivo measurements using a portable detector. The external effective dose was estimated from measurements with thermoluminescent (TL)-dosemeters worn by the participants during one month each year. In a case study, the changes in biokinetics of 137Cs during pregnancy was investigated in a woman with an unintended intake of 137Cs via mushrooms grown in the area. During pregnancy the biological half-time of caesium was 54% of that before pregnancy. The ratio of the 137Cs concentration in breast milk (Bq L-1) to that in the mother's body (Bq kg-1) was 15% one month after the child was born. The body burden of 137Cs in the Russian individuals calculated from urine samples showed a good agreement with the body burden estimated from in vivo measurements in the same individuals. Normalisation of the caesium concentration in the urine samples by the use of potassium or creatinine excretion introduced systematic differences and a larger spread in the calculated values of the 137Cs body burden as compared with calculations without normalisation. The yearly effective dose to inhabitants in the Russian villages varied between 1.2 and 2.5 mSv as a mean for all villages between 1991 and 1998 and the internal effective dose was 30-50% of the total effective dose. The external effective dose decreased on average 15% per year, while the internal effective dose varied, depending to a great extent on the availability of mushrooms. The cumulated effective dose for a 70-year period after the accident was calculated to be 100 mSv assuming that the effective dose will decrease by only the physical decay of 137Cs (2% per year) after 1998. Individuals may receive considerably higher effective doses, up to 0.5 Sv during a life-time considering the large spread in dose values among individuals.

Direct measurement of air kerma rate in air from CDCS J-type caesium-137 therapy sources using a Farmer ionization chamber.

PubMed

Poynter, A J

2000-04-01

A simple method for directly measuring the reference air kerma rate from J-type 137Cs sources using a Farmer 2571 chamber has been evaluated. The method is useful as an independent means of verifying manufacturers' test data.

[Thermodynamic forecasting of reagents composition for soils decontamination].

PubMed

Nikolaev, V P; Nikolaevskiĭ, V B; Chirkina, I V; Shcheglov, M Iu

2009-01-01

Based on thermodynamic studies, the authors conducted laboratory experiments on searching optimal composition of leaching reagents solution for soils decontamination, when contaminated with Cs-137, of activity coefficient for caesium sulfate microquantities in macrocomponents solutions. The method could be used for modelling the radionuclides phase equillibrium and relocations in soils.

CsMgPO4

PubMed Central

Strutynska, Nataliya Yu.; Zatovsky, Igor V.; Baumer, Vyacheslav N.; Slobodyanik, Nikolay S.

2009-01-01

Caesium magnesium orthophosphate is built up from MgO4 and PO4 tetra­hedra (both with . m. symmetry) linked together by corners, forming a three-dimensional framework. The Cs atoms have .m. site symmetry and are located in hexa­gonal channels running along the a- and b-axis directions. PMID:21583294

Influence of the interpellet space to the Instant Release Fraction determination of a commercial UO2 Boiling Water Reactor Spent Nuclear Fuel

NASA Astrophysics Data System (ADS)

Martínez-Torrents, A.; Serrano-Purroy, D.; Casas, I.; De Pablo, J.

2018-02-01

The contact of the coolant with the fuel pin during irradiation produces a gradient of temperature in the fuel pellet that segregates the radionuclides (RN) depending on its volatility and reactivity. This segregation determines the Instant Release Fraction (IRF), an important source of radiological risk in the performance assessment (PA) of a Deep Geologic Repository (DGR). RN segregation was studied radially in previous papers. In the present work, it was studied axially, taking into special consideration the cutting position of the solid sample to be studied. Iodine and caesium were the RN with the highest release, while the contribution of rubidium, strontium, molybdenum and technetium to the IRF depended on their chemical state. The interpellet presence (known also as dishing) effect was clearly observed for caesium, increasing its release by one order of magnitude. According to these results, one of the major contributions to the IRF comes from the RN trapped in the dishing and has to be considered in the sampling and data interpretation that will be performed for the PA of the DGR.

Coherent population trapping resonances at lower atomic levels of Doppler broadened optical lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Şahin, E; Hamid, R; Çelik, M

2014-11-30

We have detected and analysed narrow high-contrast coherent population trapping (CPT) resonances, which are induced in absorption of a weak monochromatic probe light beam by counterpropagating two-frequency pump radiation in a cell with rarefied caesium vapour. The experimental investigations have been performed by the example of nonclosed three level Λ-systems formed by spectral components of the D{sub 2} line of caesium atoms. The applied method allows one to analyse features of the CPT phenomenon directly at a given low long-lived level of the selected Λ-system even in sufficiently complicated spectra of atomic gases with large Doppler broadening. We have establishedmore » that CPT resonances in transmission of the probe beam exhibit not only a higher contrast but also a much lesser width in comparison with well- known CPT resonances in transmission of the corresponding two-frequency pump radiation. The results obtained can be used in selective photophysics, photochemistry and ultra-high resolution atomic (molecular) spectroscopy. (laser applications and other topics in quantum electronics)« less

The negative ions of strontium and barium

NASA Astrophysics Data System (ADS)

Garwan, M. A.; Kilius, L. R.; Litherland, A. E.; Nadeau, M.-J.; Zhao, X.-L.

1990-12-01

Recent theoretical calculations have predicted a tendency toward higher electron affinities for heavier alkaline elements. Experimental evidence has been obtained for the existence of strontium and barium negative ions created from pure elements in a caesium sputter ion source. Accelerator mass spectrometric techniques were employed to resolve the above elemental negative ions from the interfering molecular species.

Quantum Communications Systems

DTIC Science & Technology

2012-09-21

metrology practical. The strategy was to develop robust photonic quantum states and sensors serving as an archetype for loss-tolerant information...communications and metrology. Our strategy consisted of developing robust photonic quantum states and sensors serving as an archetype for loss-tolerant...developed atomic memories in caesium vapour, based on a stimulated Raman transition, that have demonstrated a TBP greater than 1000 and are uniquely suited

[Reduction of 137caesium contamination in wild boars by supplementing offered food with ammonium-iron-hexa-cyanoferrate].

PubMed

Morfeld, P; Reddemann, J; Schungel, P; Kienzle, E

2014-01-01

This replication study investigated whether the 137caesium (137Cs) contamination of wild boars could be relevantly reduced under field conditions by adding ammonium-iron-hexa-cyanoferrate (AFCF; Prussian blue) to the food. In 285 wild boars that had been shot in six Bavarian hunting territories during the season (November until May) between 01 November 2010 and 10 December 2011 137Cs contamination was analysed. Thirty-five animals originated from two hunting territories in which offered food had been supplemented with 1250 mg AFCF per kilogram food. The control animals showed a mean 137Cs contamination of 522 Bq/kg lean skeletal muscle meat. Direct (univariable) comparisons of the two experimental territories with the four control territories yielded a mean reduction in 137Cs contamination due to Prussian bluefeeding by -211 Bq/kg (p < 0.001). Multivariable models that took potential confounders into account (age, weight, sex, hunting date, territory) estimated the effect to be -344 Bq/kg (p < 0.05). This replication study confirmed the finding of Kienzle et al. (12) who described a statistically significant reduction in 137Cs contamination by -380 Bq/kg due to the feeding of Prussian blue in other territories.

Microhydration of caesium compounds: Cs, CsOH, CsI and Cs₂I₂ complexes with one to three H₂O molecules of nuclear safety interest.

PubMed

Sudolská, Mária; Cantrel, Laurent; Cernušák, Ivan

2014-04-01

Structure and thermodynamic properties (standard enthalpies of formation and Gibbs free energies) of hydrated caesium species of nuclear safety interest, Cs, CsOH, CsI and its dimer Cs₂I₂, with one up to three water molecules, are calculated to assess their possible existence in severe accident occurring to a pressurized water reactor. The calculations were performed using the coupled cluster theory including single, double and non-iterative triple substitutions (CCSD(T)) in conjunction with the basis sets (ANO-RCC) developed for scalar relativistic calculations. The second-order spin-free Douglas-Kroll-Hess Hamiltonian was used to account for the scalar relativistic effects. Thermodynamic properties obtained by these correlated ab initio calculations (entropies and thermal capacities at constant pressure as a function of temperature) are used in nuclear accident simulations using ASTEC/SOPHAEROS software. Interaction energies, standard enthalpies and Gibbs free energies of successive water molecules addition determine the ordering of the complexes. CsOH forms the most hydrated stable complexes followed by CsI, Cs₂I₂, and Cs. CsOH still exists in steam atmosphere even at quite high temperature, up to around 1100 K.

Chemoselective room temperature E1cB N-N cleavage of oxazolidinone hydrazides from enantioselective aldehyde α-hydrazination: synthesis of (+)-1,4-dideoxyallonojirimycin.

PubMed

Ferreira, Jasmin; Rees-Jones, Sophie C M; Ramaotsoa, Valerie; Msutu, Ath'enkosi; Hunter, Roger

2016-02-07

Room temperature E1cB N-N cleavage of oxazolidinone hydrazides via N-alkylation with diethyl bromomalonate and potassium or caesium carbonate as base in acetonitrile is presented. The new method has a much improved chemoselectivity, which is illustrated by a concise total synthesis of the piperidine iminosugar (+)-1,4-dideoxyallonojirimycin.

Distribution of 137Cs in surface soil of Fraser's Hill, Pahang, Malaysia

NASA Astrophysics Data System (ADS)

Bakar, Ahmad Sanadi Abu; Hamzah, Zaini; Saat, Ahmad

2017-01-01

Caesium-137 (137Cs) in an anthropogenic radionuclide originated from the fission of fissile materials. Nuclear weapons testing during the 1960s and the Chernobyl disaster introduced substantial amount of 137Cs into the atmosphere that are then eventually deposited back to earth's surface. Caesium-137 can be used as tracer to study soil movements since it adsorbs to soil particles. This paper aims to describe the distribution of 137Cs in surface soil of Fraser's Hill, Pahang, determine the levels of 137Cs here compared to other areas, and to check correlation of 137Cs levels to physical data. A series of sampling were carried out between February 2014 and August 2015. Soil samples were taken from 31 locations using soil scraper. The samples were then taken to the laboratory to be dried, homogenized, grinded and sieved. The activity concentration of 137Cs in the samples was determined using gamma spectroscopy. The activity concentration was found to be between 0.26 Bq/kg and 5.14 Bq/kg. Although this paper only studies surface soil, 137Cs is expected to be present within the soil body. Further study of 137Cs in the soil body can be used to predictive model for soil erosion.

Mineral resource of the month: cesium

USGS Publications Warehouse

Angulo, Marc A.

2010-01-01

The article offers information on cesium, a golden alkali metal derived from the Latin word caesium which means bluish gray. It mentions that cesium is the first element discovered with the use of spectroscopy. It adds that the leading producer and supplier of cesium is Canada and there are 50,000 kilograms of cesium consumed of the world in a year. Moreover, it states that only 85% of the cesium formate can be retrieved and recycled.

Simple theoretical determination of the thickness of an alkali monolayer adsorbed on a jellium surface

NASA Astrophysics Data System (ADS)

Wojciechowski, K. F.; Rogowska, J. M.; Bogdanów, H.

1991-05-01

The thickness of a jellium slab representing an alkali monolayer on a jellium surface has been calculated, using parametrized trial functions for the electron density profile at the surface fulfilling the Budd-Vannimenus theorem and the charge neutrality condition. Reasonable values of the thicknesses of potassium, sodium, rubidium and caesium monolayers are obtained, which, contrary to earlier assumptions, depend on the bulk electron density of the substrate.

Estimating Erosion Rates using Caesium-137 Tracers in the Ethiopian Highlands

NASA Astrophysics Data System (ADS)

Guzman, C. D.; Tilahun, S. A.; Zegeye, A. D.; Yitaferu, B.; Kay, R. W.; Steenhuis, T. S.

2016-12-01

The effects and seriousness of soil erosion have been gaining more attention recently, especially with respect to shortening the life of reservoirs for hydroelectric power generation and diminished agricultural productivity. A central aim of this study on soil erosion and conservation is to compare and contrast estimates and identification of eroding areas and patterns in the Ethiopian highlands. In Debre Mawi, Ethiopia, we examined spatial variations in erosion from an agricultural watershed using the soil-adsorbed radionuclide caesium-137(Cs-137) as a sediment tracer. Sixteen sites were monitored in this small watershed 30 km south of Lake Tana, with characteristic semi-monsoonal rains, during the long (kremt) rainy season for topsoil depth change, groundwater table height, and ceasium-137 inventory. These sixteen sites are divided among cropped and fallow land and are spread out among upslope, midslope, and downslope areas within the watershed. The Cs-137 tracer method mapped the upland mildly sloping areas to be eroding at a greater average rate than any of the mid-slope or toe-slope areas. From comparisons with the sediment concentration in the downstream weir and groundwater table measurements, we draw information helpful in understanding why and how sediment concentration and erosion decreases or increases at certain times during the rainy season. By combining these different detection methods we hope to enable the development of more effective and sustainable conservation practices.

An overview of negative hydrogen ion sources for accelerators

NASA Astrophysics Data System (ADS)

Faircloth, Dan; Lawrie, Scott

2018-02-01

An overview of high current (>1 mA) negative hydrogen ion (H-) sources that are currently used on particle accelerators. The current understanding of how H- ions are produced is summarised. Issues relating to caesium usage are explored. The different ways of expressing emittance and beam currents are clarified. Source technology naming conventions are defined and generalised descriptions of each source technology are provided. Examples of currently operating sources are outlined, with their current status and future outlook given. A comparative table is provided.

Preliminary results from the Small Negative Ion Facility (SNIF) at CCFE

NASA Astrophysics Data System (ADS)

Zacks, J.; McAdams, R.; Booth, J.; Flinders, K.; Holmes, A. J. T.; Simmonds, M.; Stevens, B.; Stevenson, P.; Surrey, E.; Warder, S.; Whitehead, A.; Young, D.

2013-02-01

At Culham Centre for Fusion Energy, a new beam extraction test facility has been built with the purpose of studying and enhancing negative ion beam production and transport. The multipole hydrogen ion source is based on a RF generated plasma using a continuous 5kW power supply operating at the industrial standard frequency of 13.56MHz. The cylindrical source has a diameter of 30cm and a depth of 20cm, with a flat spiral antenna driving the source through a quartz window. The magnet configuration is arranged to produce a dipole filter field across the ion source close to the plasma grid. The plasma load is matched to the RF generator using a Pi matching network. The accelerator uses a single extraction aperture of 14mm diameter, with a biased insert for electron suppression. The accelerator is a triode design with a beam energy of up to 30kV. The beamline consists of a turbomolecular pumped vacuum tank with an instrumented beam dump and ports for additional diagnostics. The ITER Neutral Beam source operates with the enhancement of caesium, which, when scaled up to a reactor, will be heavily consumed. The small size of SNIF allows for fast turn around of modifications and alternative materials to caesium can be tested. A full description of the facility and planned diagnostics is given. Initial results are presented, including measurements and calculations of the plasma load on the RF generator, and beam extraction measurements.

Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant

PubMed Central

Furuki, Genki; Imoto, Junpei; Ochiai, Asumi; Yamasaki, Shinya; Nanba, Kenji; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C.; Utsunomiya, Satoshi

2017-01-01

The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP. All of the CsMPs (with sizes of 2.0–3.4 μm) comprise SiO2 glass matrices and ~10-nm-sized Zn–Fe-oxide nanoparticles associated with a wide range of Cs concentrations (1.1–19 wt% Cs as Cs2O). Trace amounts of U are also associated with the Zn–Fe oxides. The nano-texture in the CsMPs records multiple reaction-process steps during meltdown in the severe FDNPP accident: Melted fuel (molten core)-concrete interactions (MCCIs), incorporating various airborne fission product nanoparticles, including CsOH and CsCl, proceeded via SiO2 condensation over aggregates of Zn-Fe oxide nanoparticles originating from the failure of the reactor pressure vessels. Still, CsMPs provide a mechanism by which volatile and low-volatility radionuclides such as U can reach the environment and should be considered in the migration model of Cs and radionuclides in the current environment surrounding the FDNPP. PMID:28198440

Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Furuki, Genki; Imoto, Junpei; Ochiai, Asumi; Yamasaki, Shinya; Nanba, Kenji; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C.; Utsunomiya, Satoshi

2017-02-01

The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP. All of the CsMPs (with sizes of 2.0-3.4 μm) comprise SiO2 glass matrices and ~10-nm-sized Zn-Fe-oxide nanoparticles associated with a wide range of Cs concentrations (1.1-19 wt% Cs as Cs2O). Trace amounts of U are also associated with the Zn-Fe oxides. The nano-texture in the CsMPs records multiple reaction-process steps during meltdown in the severe FDNPP accident: Melted fuel (molten core)-concrete interactions (MCCIs), incorporating various airborne fission product nanoparticles, including CsOH and CsCl, proceeded via SiO2 condensation over aggregates of Zn-Fe oxide nanoparticles originating from the failure of the reactor pressure vessels. Still, CsMPs provide a mechanism by which volatile and low-volatility radionuclides such as U can reach the environment and should be considered in the migration model of Cs and radionuclides in the current environment surrounding the FDNPP.

Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant.

PubMed

Furuki, Genki; Imoto, Junpei; Ochiai, Asumi; Yamasaki, Shinya; Nanba, Kenji; Ohnuki, Toshihiko; Grambow, Bernd; Ewing, Rodney C; Utsunomiya, Satoshi

2017-02-15

The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP. All of the CsMPs (with sizes of 2.0-3.4 μm) comprise SiO 2 glass matrices and ~10-nm-sized Zn-Fe-oxide nanoparticles associated with a wide range of Cs concentrations (1.1-19 wt% Cs as Cs 2 O). Trace amounts of U are also associated with the Zn-Fe oxides. The nano-texture in the CsMPs records multiple reaction-process steps during meltdown in the severe FDNPP accident: Melted fuel (molten core)-concrete interactions (MCCIs), incorporating various airborne fission product nanoparticles, including CsOH and CsCl, proceeded via SiO 2 condensation over aggregates of Zn-Fe oxide nanoparticles originating from the failure of the reactor pressure vessels. Still, CsMPs provide a mechanism by which volatile and low-volatility radionuclides such as U can reach the environment and should be considered in the migration model of Cs and radionuclides in the current environment surrounding the FDNPP.

Soil anomaly mapping using a caesium magnetometer: Limits in the low magnetic amplitude case

NASA Astrophysics Data System (ADS)

Mathé, Vivien; Lévêque, François; Mathé, Pierre-Etienne; Chevallier, Claude; Pons, Yves

2006-03-01

Caesium magnetometers are new tools for soil property mapping with a decimetric resolution [Mathé, V., Lévêque, F., 2003. High resolution magnetic survey for soil monitoring: detection of drainage and soil tillage effects. Earth and Planetary Science Letters 212 (1-2), 241-251]. However, when the magnetic anomalies are only a few nanoteslas (nT), the geologic and pedogenic signal must first be isolated from magnetic disturbances for this method to be useful. This paper investigates the instrumental artifacts and environmental disturbances to adapt the survey protocol to slightly magnetic soils. Among the possible instrumental sources of disturbances listed and quantified, the most significant are: 1) The battery effect upon sensors 2 m away (classic protocol, about ± 0.15 nT) while increasing this distance up to 10 m cancelled it; 2) The noise level of magnetometers and sensors, which, according to tests on two magnetometers and three sensors, rarely and randomly exceeds 0.1 nT, but seems to increase with the electronic component age. Among the environmental disturbances, temporal variations such as diurnal variation or fluctuations linked to the moving of metallic masses play a major role, although the pseudogradient or base-station methods have commonly cancelled them. The efficiency of the latter is strongly dependent on the source nature. However, the ground currents and electromagnetic fields propagating in soils cause more problems. As a first step to better understand such disturbance sources, uncommon magnetic signal variations supposedly due to electromagnetic wave conversions and likely linked to the railway traffic are presented. Based on previous results, an adapted protocol using one magnetometer and two caesium sensors (0.3 and 1.6 m above the surface) is proposed to increase the signal / noise ratio. At first, to maintain an accurate horizontal and vertical location of the sensors, the latter are affixed to a wooden handcart running on plastic rails. Rails adapt to micro-topography, thereby decreasing strongly the soil-sensors distance variations. Anomalies due to topography rarely exceed 0.1 nT. Finally, a method to remove diurnal variations from high-resolution magnetic maps is proposed. Parallel profiles performed successively are adjusted by a cross-profile. Assuming that the temporal variations during each profile are negligible (less than 0.05 nT), this technique, contrary to the pseudogradient, preserves both the decimetric and the metric anomalies (gain of more than 1 nT).

Heterodyne optical phase-locking of extended-cavity semiconductor lasers at 9 GHz

NASA Astrophysics Data System (ADS)

Santarelli, G.; Clairon, A.; Lea, S. N.; Tino, G. M.

1994-01-01

In order to stimulate atomic velocity-selective Raman transitions on the 852 nm caesium D 2 line in an atomic fountain clock, two extended-cavity diode lasers have been optically phase-locked at a frequency offset of 9.192 GHz. The measured linewidth (fwhm) of the free-running lasers is 50 kHz. The phase-locked loop bandwidth, evaluated by observing the frequency noise spectrum, is 3.7 MHz and the phase error variance is found to be no more than 4 × 10 -3 rad 2.

Development Of Frequency Transfer Via Optical Fiber Link at NICT

DTIC Science & Technology

2008-12-01

al., 2006 “Comparison between frequency standards in Europe and the USA at the 10-15 uncertainty level,” Metrologia , 43, 109-120. [4] H. Kiuchi, T...M. Hosokawa, 2008, “Evaluation of caesium atomic fountain NICT-CsF1,” Metrologia , 45, 139-148. [12] M. Kumagai, H. Ito, G. Santarelli, C. Locke, J...free-run O ve rla pp in g Al la n D ev ia tio n Averaging time [sec] 40th Annual Precise Time and Time Interval (PTTI) Meeting 100 101 102 103

MOVEMENT OF STRONTIUM AND CAESIUM IN SOILS AND ITS SIGNIFICANCE IN STUDIES ON THE CONTAMINATION OF FOOD CHAINS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, R.S.; Shone, M.G.T.

ABS>Experimental results are given of a long term study on the migration and fixation of strontium and cesium in several types of soil The investigations were designed to approximate to field conditions in which the soil remained undisturbed by cultivation. The effects of the addition of nutrients and of a permanent crop of ryegrass grown on the artificially contaminated soils were also examined. The relevance of processes of migration and fixation to assessments of the uptake of strontium and cesium by crop plants is considered in the light of field experiments. (auth)

Dispersal, deposition and collective doses after the Chernobyl disaster.

PubMed

Fairlie, Ian

2007-01-01

This article discusses the dispersal, deposition and collective doses of the radioactive fallout from the Chernobyl accident. It explains that, although Belarus, Ukraine and Russia were heavily contaminated by the Chernobyl fallout, more than half of the fallout was deposited outside these countries, particularly in Western Europe. Indeed, about 40 per cent of the surface area of Europe was contaminated. Collective doses are predicted to result in 30,000 to 60,000 excess cancer deaths throughout the northern hemisphere, mostly in western Europe. The article also estimates that the caesium-137 source term was about a third higher than official figures.

1998 Conference on Precision Electromagnetic Measurements Digest. Proceedings.

NASA Astrophysics Data System (ADS)

Nelson, T. L.

The following topics were dealt with: fundamental constants; caesium standards; AC-DC transfer; impedance measurement; length measurement; units; statistics; cryogenic resonators; time transfer; QED; resistance scaling and bridges; mass measurement; atomic fountains and clocks; single electron transport; Newtonian constant of gravitation; stabilised lasers and frequency measurements; cryogenic current comparators; optical frequency standards; high voltage devices and systems; international compatibility; magnetic measurement; precision power measurement; high resolution spectroscopy; DC transport standards; waveform acquisition and analysis; ion trap standards; optical metrology; quantised Hall effect; Josephson array comparisons; signal generation and measurement; Avogadro constant; microwave networks; wideband power standards; antennas, fields and EMC; quantum-based standards.

[From Chernobyl to Morsleben--a public health observation].

PubMed

Thriene, B

1999-11-01

On April 26, 1986, a serious reactor accident occurred at the Chernobyl nuclear power plant. A total radioactivity of 2 x 10(18) becquerel, i.e. 3.5% of the reactor inventory were released spreading throughout Europe. Radioactive tracers were iodine 131 (with a half-life of 8 days) and caesium 137 (with a half-life of 30 years). Measurements made in Magdeburg by the Institute of Hygiene on May 5th after a heavy thunderstorm indicated a considerable radioactive contamination. Measurements revealed 75,000 bq/kg in grasses, 44,000 bq/litre in storm water and 40,000 bq/kg in garden soil, however, these high values decreased to normal by the end of 1986. The paper describes a stay in Chernobyl in 1989 and the environmental and working conditions prevailing at site. An increase of the cancer rate in the contaminated areas was not observed until 1990; however, thyroid tumours increased in children in Belorussia after that time. The current caesium load of the soils in the area is 10(6) becquerel/cubic metre. As much as 480,000 bq/kg were measured in dried mushrooms picked in the autumn of 1997. Assuming a mean natural exposure to radiation of the population in Germany of 2.4 millisievert/year (mSv/a), the additional load caused by the Chernobyl accident was 5% in 1986, falling to below 0.1% in 1996. Today, 19 nuclear power plants are operating in Germany for power generation. Radioactive substances are used in medicine, research and industry. An opinion on the safety of transports and final dumping of radioactive waste is given, based on a visit to the Morsleben final dump site. The use of nuclear energy and a percentage replacement by renewable energies are discussed from a regional and global perspective (climate protection).

Improvements of the versatile multiaperture negative ion source NIO1

NASA Astrophysics Data System (ADS)

Cavenago, M.; Serianni, G.; De Muri, M.; Veltri, P.; Antoni, V.; Baltador, C.; Barbisan, M.; Brombin, M.; Galatá, A.; Ippolito, N.; Kulevoy, T.; Pasqualotto, R.; Petrenko, S.; Pimazzoni, A.; Recchia, M.; Sartori, E.; Taccogna, F.; Variale, V.; Zaniol, B.; Barbato, P.; Baseggio, L.; Cervaro, V.; Fasolo, D.; Franchin, L.; Ghiraldelli, R.; Laterza, B.; Maniero, M.; Martini, D.; Migliorato, L.; Minarello, A.; Molon, F.; Moro, G.; Patton, T.; Ravarotto, D.; Rizzieri, R.; Rizzolo, A.; Sattin, M.; Stivanello, F.; Zucchetti, S.

2017-08-01

The ion source NIO1 (Negative Ion Optimization 1) was developed and installed as a reduced-size model of multi-aperture sources used in neutral beam injectors. NIO1 beam optics is optimized for a 135 mA H- current (subdivided in 9 beamlets) at a Vs = 60 kV extraction voltage, with an electron-to-ion current ratio Rj up to 2. Depending on gas pressure used, NIO1 was up to now operated with Vs < 25 kV for beam extraction and Vs = 60 kV for insulation tests. The distinction between capacitively coupled plasma (E-mode, consistent with a low electron density plasma ne) and inductively coupled plasma (H-mode, requiring larger ne) was clearly related to several experimental signatures, and was confirmed for several gases, when applied radiofrequency power exceeds a given threshold Pt (with hysteresis). For hydrogen Pt was reduced below 1 kW, with a clean rf window and molybdenum liners on other walls; for oxygen Pt ≤ 400 W. Beams of H- and O- were separately extracted; since no caesium is yet introduced into the source, the expected ion currents are lower than 5 mA; this requires a lower acceleration voltage Vs (to keep the same perveance). NIO1 caesium oven was separately tested and Cs dispensers are in development. Increasing the current in the magnetic filter circuit, modifying its shape, and increasing the bias voltage were helpful to reduce Rj (still very large up to now, about 150 for oxygen, and 40 for hydrogen), in qualitative agreement with theoretical and numerical models. A second bias voltage was tested for hydrogen. Beam footprints and a spectral emission sample are shown.

Baseline Caesium-137 and Plutonium-239+240 inventory assessment for Central Europe

NASA Astrophysics Data System (ADS)

Meusburger, Katrin; Borelli, Pasquale; Evrard, Olivier; Ketterer, Michael; Mabit, Lionel; van Oost, Kristof; Alewell, Christine; Panagos, Panos

2017-04-01

Artificial fallout radionuclides (FRNs) such as Caesium-137 and Plutonium-239+240 released as products of the thermonuclear weapons testing that took place from the mid-1950s to the early 1980s and from nuclear power plant accidents (e.g. Chernobyl) are useful tools to quantify soil redistribution. In combination with geostatistics, FRNs may have the potential to bridge the gap between small scale process oriented studies and modelling that simplifies processes and effects over large spatial scales. An essential requirement for the application of FRNs as soil erosion tracers is the establishment of the baseline fallout at undisturbed sites before its comparison to those inventories found at sites undergoing erosion/accumulation. For this purpose, undisturbed topsoil (0-20cm) samples collected in 2009 within the framework of the Land Use/Cover Area frame Survey (LUCAS) have been measured by gamma-spectrometry and ICP-MS to determine 137Cs (n=145) and 239+240Pu (n=108) activities. To restrict the analysis to undisturbed reference sites a geospatial database query selecting only sites having a slope angle <2 degree, outside riparian zones (to avoid depositional sites) and under permanent grassland cover (according to CORINE Land Cover and Landsat) was applied. This study reports preliminary results on the feasibility of establishing a 137Cs and 239+240Pu baseline inventory map for Central Europe. The 137Cs/239+240Pu activity ratios will further allow assessing the rate and the spatial variability of 137Cs Chernobyl fallout. The establishment of such baseline inventory map will provide a unique opportunity to assess soil redistribution for a comparable time-frame (1953-2009) following a harmonised methodological protocol across national boundaries.

The high affinity K+ transporter AtHAK5 plays a physiological role in planta at very low K+ concentrations and provides a caesium uptake pathway in Arabidopsis.

PubMed

Qi, Zhi; Hampton, Corrina R; Shin, Ryoung; Barkla, Bronwyn J; White, Philip J; Schachtman, Daniel P

2008-01-01

Caesium (Cs(+)) is a potentially toxic mineral element that is released into the environment and taken up by plants. Although Cs(+) is chemically similar to potassium (K(+)), and much is known about K(+) transport mechanisms, it is not clear through which K(+) transport mechanisms Cs(+) is taken up by plant roots. In this study, the role of AtHAK5 in high affinity K(+) and Cs(+) uptake was characterized. It is demonstrated that AtHAK5 is localized to the plasma membrane under conditions of K(+) deprivation, when it is expressed. Growth analysis showed that AtHAK5 plays a role during severe K(+) deprivation. Under K(+)-deficient conditions in the presence of Cs(+), Arabidopsis seedlings lacking AtHAK5 had increased inhibition of root growth and lower Cs(+) accumulation, and significantly higher leaf chlorophyll concentrations than wild type. These data indicate that, in addition to transporting K(+) in planta, AtHAK5 also transports Cs(+). Further experiments showed that AtHAK5 mediated Cs(+) uptake into yeast cells and that, although the K(+) deficiency-induced expression of AtHAK5 was inhibited by low concentrations of NH(4)(+) in planta, Cs(+) uptake by yeast was stimulated by low concentrations of NH(4)(+). Interestingly, the growth of the Arabidopsis atakt1-1 mutant was more sensitive to Cs(+) than the wild type. This may be explained, in part, by increased expression of AtHAK5 in the atakt1-1 mutant. It is concluded that AtHAK5 is a root plasma membrane uptake mechanism for K(+) and Cs(+) under conditions of low K(+) availability.

Caesium and strontium accumulation in shoots of Arabidopsis thaliana: genetic and physiological aspects

PubMed Central

Kanter, Ulrike; Hauser, Andreas; Michalke, Bernhard; Dräxl, Stephan; Schäffner, Anton R.

2010-01-01

Due to the physico-chemical similarities of caesium (Cs+) to potassium (K+) on the one hand and strontium (Sr2+) to calcium (Ca2+) on the other hand, both elements can easily be taken up by plants and thus enter the food chain. This could be detrimental when radionuclides such as 137Cs and 90Sr are involved. In this study, both genetic and physiological aspects of Cs+ and Sr2+ accumulation in Arabidopsis thaliana were investigated using 86 Arabidopsis accessions and a segregating F2 population of the low Cs+ accumulating Sq-1 (Ascot, UK) crossed with the high uptaking Sorbo (Khurmatov, Tajikistan). Hydroponically grown plants were exposed to subtoxic levels of Cs+ and Sr2+ using radioactive isotopes as tracers. In the natural accessions shoot concentration of Cs+ as well as Sr2+ varied about 2-fold, whereas its heritability ranged for both ions between 0.60 and 0.73. Shoot accumulation of Cs+ and Sr2+ could be compromised by increasing concentrations of their essential analogues K+ and Ca2+, respectively, causing a reduction of up to 80%. In the case of the segregating F2/F3 population Sq-1×Sorbo, this study identified several QTL for the trait Cs+ and Sr2+ accumulation, with main QTL on chromosomes 1 and 5. According to the correlation and discrimination surveys combined with QTL-analysis Cs+ and Sr2+ uptake seemed to be mediated mostly via non-selective cation channels. A polymorphism, affecting amino acids close to the K+-pore of one candidate, CYCLIC-NUCLEOTIDE-GATED CHANNEL 1 (CNGC1), was identified in Sorbo and associated with high Cs+ concentrating accessions. PMID:20624763

Efficiency of Cs-free materials for negative ion production in H2 and D2 plasmas

NASA Astrophysics Data System (ADS)

Friedl, R.; Kurutz, U.; Fantz, U.

2017-08-01

High power negative ion sources use caesium to reduce the work function of the converter surface which significantly increases the negative ion yield. Caesium, however, is a very reactive alkali-metal and shows complex redistribution dynamics in consequence of plasma-surface-interaction. Thus, maintaining a stable and homogenous low work function surface is a demanding task, which is not easily compatible with the RAMI issues (reliability, availability, maintainability, inspectability) for a future DEMO fusion reactor. Hence, Cs-free alternative materials for efficient negative ion formation are desirable. At the laboratory experiment HOMER materials which are referred to as promising are investigated under identical and ion source relevant parameters: the refractory metals Ta and W, non-doped and boron-doped diamond as well as materials with inherent low work function (lanthanum-doped molybdenum, MoLa and lanthanum hexaboride, LaB6). The results are compared to the effect of in-situ caesiation, which at HOMER leads to a maximal increase of the negative ion density by a factor of 2.5. Among the examined samples low work function materials are most efficient. In particular, MoLa leads to an increase of almost 50 % compared to pure volume formation. The difference to a caesiated surface can be attributed to the still higher work function of MoLa, which is expected to be slightly below 3 eV. Using deuterium instead of hydrogen leads to increased atomic and positive ion densities, while comparable negative ion densities are achieved. In contrast to the low work function materials, bulk samples of the refractory metals as well as carbon based materials have no enhancing effect on H-, where the latter materials furthermore show severe erosion due to the hydrogen plasma.

Radionuclides deposition and fine sediment transport in a forested watershed, central Japan

NASA Astrophysics Data System (ADS)

Nam, S.; Gomi, T.; Kato, H.; Tesfaye, T.; Onda, Y.

2011-12-01

We investigated radionuclides deposition and fine sediment transport in a 13 ha headwater watershed, Tochigi prefecture, located in 98.94 km north of Tokyo. The study site was within Karasawa experimental forest, Tokyo University of Agriculture and Technology. We conducted fingerprinting approach, based on the activities of fallout radionuclides, including caesium-134 (Cs-134) caesium-137 (Cs-137) and excess lead-210 (Pb-210ex). For indentifying specific sources of fine sediment, we sampled tree, soil on forested floor, soil on logging road surface, stream bed and stream banks. We investigated the radionuclides (i.e., as Cs-134, Cs-137 and Pb-210ex) deposition on tree after accident of nuclear power plants on March 11, 2011. We sampled fruits, leaves, branches, stems, barks on Japanese cedar (Sugi) and Japanese cypress (Hinoki). To analyze the samples, gammaray spectrometry was performed at a laboratory at the University of Tsukuba (Tsukuba City, Japan) using n-type coaxial low-energy HPGe gamma detectors (EGC-200-R and EGC25-195-R of EURYSIS Co., Lingolsheim, France) coupled with a multichannel analyzer. We also collected soil samples under the forest canopy in various soil depths from 2, 5, 10, 20, 30 cm along transect of hillslopes. Samples at forest road were collected road segments crossing on the middle section of monitoring watersheds. Fine sediment transport in the streams were collected at the outlet of 13 ha watersheds using integrated suspended sediment samplers. This study indicates the some portion of radio nuclide potentially remained on the tree surface. Part of the deposited radionuclides attached to soil particles and transported to the streams. Most of the fine sediment can be transported on road surface and/or near stream side (riparian zones).

Bright triplet excitons in caesium lead halide perovskites

NASA Astrophysics Data System (ADS)

Becker, Michael A.; Vaxenburg, Roman; Nedelcu, Georgian; Sercel, Peter C.; Shabaev, Andrew; Mehl, Michael J.; Michopoulos, John G.; Lambrakos, Samuel G.; Bernstein, Noam; Lyons, John L.; Stöferle, Thilo; Mahrt, Rainer F.; Kovalenko, Maksym V.; Norris, David J.; Rainò, Gabriele; Efros, Alexander L.

2018-01-01

Nanostructured semiconductors emit light from electronic states known as excitons. For organic materials, Hund’s rules state that the lowest-energy exciton is a poorly emitting triplet state. For inorganic semiconductors, similar rules predict an analogue of this triplet state known as the ‘dark exciton’. Because dark excitons release photons slowly, hindering emission from inorganic nanostructures, materials that disobey these rules have been sought. However, despite considerable experimental and theoretical efforts, no inorganic semiconductors have been identified in which the lowest exciton is bright. Here we show that the lowest exciton in caesium lead halide perovskites (CsPbX3, with X = Cl, Br or I) involves a highly emissive triplet state. We first use an effective-mass model and group theory to demonstrate the possibility of such a state existing, which can occur when the strong spin-orbit coupling in the conduction band of a perovskite is combined with the Rashba effect. We then apply our model to CsPbX3 nanocrystals, and measure size- and composition-dependent fluorescence at the single-nanocrystal level. The bright triplet character of the lowest exciton explains the anomalous photon-emission rates of these materials, which emit about 20 and 1,000 times faster than any other semiconductor nanocrystal at room and cryogenic temperatures, respectively. The existence of this bright triplet exciton is further confirmed by analysis of the fine structure in low-temperature fluorescence spectra. For semiconductor nanocrystals, which are already used in lighting, lasers and displays, these excitons could lead to materials with brighter emission. More generally, our results provide criteria for identifying other semiconductors that exhibit bright excitons, with potential implications for optoelectronic devices.

High-affinity nitrate/nitrite transporters NrtA and NrtB of Aspergillus nidulans exhibit high specificity and different inhibitor sensitivity

PubMed Central

Akhtar, Naureen; Karabika, Eugenia; Kinghorn, James R.; Glass, Anthony D.M.; Unkles, Shiela E.

2015-01-01

The NrtA and NrtB nitrate transporters are paralogous members of the major facilitator superfamily in Aspergillus nidulans. The availability of loss-of-function mutations allowed individual investigation of the specificity and inhibitor sensitivity of both NrtA and NrtB. In this study, growth response tests were carried out at a growth-limiting concentration of nitrate (1 mM) as the sole nitrogen source, in the presence of a number of potential nitrate analogues at various concentrations, to evaluate their effect on nitrate transport. Both chlorate and chlorite inhibited fungal growth, with chlorite exerting the greater inhibition. The main transporter of nitrate, NrtA, proved to be more sensitive to chlorate than the minor transporter, NrtB. Similarly, the cation caesium was shown to exert differential effects, strongly inhibiting the activity of NrtB, but not NrtA. In contrast, no inhibition of nitrate uptake by NrtA or NrtB transporters was observed in either growth tests or uptake assays in the presence of bicarbonate, formate, malonate or oxalate (sulphite could not be tested in uptake assays owing to its reaction with nitrate), indicating significant specificity of nitrate transport. Kinetic analyses of nitrate uptake revealed that both chlorate and chlorite inhibited NrtA competitively, while these same inhibitors inhibited NrtB in a non-competitive fashion. The caesium ion appeared to inhibit NrtA in a non-competitive fashion, while NrtB was inhibited uncompetitively. The results provide further evidence of the distinctly different characteristics as well as the high specificity of nitrate uptake by these two transporters. PMID:25855763

Unusual centrosymmetric structure of [M(18-crown-6)](+) (M = Rb, Cs and NH4) complexes stabilized in an environment of hexachloridoantimonate(V) anions.

PubMed

Ponomarova, Vira V; Rusanova, Julia A; Rusanov, Eduard B; Domasevitch, Konstantin V

2015-10-01

In (1,4,7,10,13,16-hexaoxacyclooctadecane)rubidium hexachloridoantimonate(V), [Rb(C12H24O6)][SbCl6], (1), and its isomorphous caesium {(1,4,7,10,13,16-hexaoxacyclooctadecane)caesium hexachloridoantimonate(V), [Cs(C12H24O6)][SbCl6]}, (2), and ammonium {ammonium hexachloridoantimonate(V)-1,4,7,10,13,16-hexaoxacyclooctadecane (1/1), (NH4)[SbCl6]·C12H24O6}, (3), analogues, the hexachloridoantimonate(V) anions and 18-crown-6 molecules reside across -3 axes passing through the Sb atoms and the centroids of the 18-crown-6 groups, both of which coincide with centres of inversion. The Rb(+) [in (1)], Cs(+) [in (2)] and NH4(+) [in (3)] cations are situated inside the cavity of the 18-crown-6 ring; they are situated on -3 axes and are equally disordered about centres of inversion, deviating from the centroid of the 18-crown-6 molecule by 0.4808 (13), 0.9344 (7) and 0.515 (8) Å, respectively. Interaction of the ammonium cation and the 18-crown-6 group is supported by three equivalent hydrogen bonds [N...O = 2.928 (3) Å and N-H...O = 162°]. The centrosymmetric structure of [Cs(18-crown-6)](+), with the large Cs(+) cation approaching the centre of the ligand cavity, is unprecedented and accompanied by unusually short Cs-O bonds [2.939 (2) and 3.091 (2) Å]. For all three compounds, the [M(18-crown-6)](+) cations and [SbCl6](-) anions afford linear stacks along the c axis, with the cationic complexes embedded between pairs of inversion-related anions.

Forage grasses with lower uptake of caesium and strontium could provide ‘safer’ crops for radiologically contaminated areas

PubMed Central

Beresford, Nicholas A.; Crout, Neil M. J.; Lovatt, J. Alan; Thomson, Russell; Broadley, Martin R.

2017-01-01

Substitution of a species or cultivar with higher uptake of an element by one with lower uptake has been proposed as a remediation strategy following accidental releases of radioactivity. However, despite the importance of pasture systems for radiological dose, species/cultivar substitution has not been thoroughly investigated for forage grasses. 397 cultivars from four forage grass species; hybrid ryegrass (Lolium perenne L. x Lolium multiflorum Lam.), perennial ryegrass (Lolium perenne L.), Italian ryegrass (Lolium multiflorum Lam.) and tall fescue (Festuca arundinacea Shreb.); were sampled from 19 field-based breeding experiments in Aberystwyth and Edinburgh (UK) in spring 2013 and analysed for caesium (Cs) and strontium (Sr) concentrations. In order to calculate concentration ratios (CRs; the concentration of an element in a plant in relation to the concentration in the soil), soils from the experiments were also analysed to calculate extractable concentrations of Cs and Sr. To test if cultivars have consistently low Cs and Sr concentration ratios, 17 hybrid ryegrass cultivars were sampled from both sites again in summer 2013 and spring and summer 2014. Tall fescue cultivars had lower Cs and Sr CRs than the other species. Three of the selected 17 hybrid ryegrass cultivars had consistently low Cs CRs, two had consistently low Sr CRs and one had consistently low Cs and Sr CRs. Cultivar substitution could reduce Cs CRs by up to 14-fold and Sr CRs by 4-fold in hybrid ryegrass. The identification of species and cultivars with consistently low CRs suggests that species or cultivar substitution could be an effective remediation strategy for contaminated areas. PMID:28459808

Développement mathématique appliqué à une future échelle de temps.

NASA Astrophysics Data System (ADS)

Andreucci, C.

The LPTF time section is in charge of the generation and dissemination of the French time scale (TA(F)). With the use of GPS time transfer and the replacement of the old generation of commercial caesium clocks, the quality of the timing data has changed rapidly. Consequently, the current time scale algorithm is not adapted to award a weight to the new clocks in relation with there quality. So a new algorithm has been built, with a more sensitive statistics processing. Tests carried out on real clock data covering the last few years, show improvement of the stability of the time scale.

Analysis of the structure of fish lymphocystis disease virions from skin tumours of pleuronectes.

PubMed

Samalecos, C P

1986-01-01

Virions of fish lymphocystis disease (FLDV) from tumour-carrying-fishes (flounder, dab, plaice and gurnard) collected in the North Sea were isolated directly from the tumours and purified by sucrose and subsequent caesium chloride gradient centrifugation. They were studied by electron microscopy using embedding methods, negative staining and using metal shadowing methods. Tumours of dermal connective fish tissue showed particles with hexagonal outlines. Occasionally, an "empty structure" was observed. Subunits of the virus membrane were identified after 3 per cent phosphotungstic acid (PTA) or 0.2 per cent Ruthenium red (RR) staining. FLDV measures 199-227 nm in diameter.

Potential energy surfaces of the low-lying electronic states of the Li + LiCs system

NASA Astrophysics Data System (ADS)

Jasik, P.; Kilich, T.; Kozicki, J.; Sienkiewicz, J. E.

2018-03-01

Ab initio quantum chemistry calculations are performed for the mixed alkali triatomic system. Global minima of the ground and first excited doublet states of the trimer are found and Born-Oppenheimer potential energy surfaces of the Li atom interacting with the LiCs molecule were calculated for these states. The lithium atom is placed at various distances and bond angles from the lithium-caesium dimer. Three-body nonadditive forces of the Li2Cs molecule in the global minimum are investigated. Dimer-atom interactions are found to be strongly attractive and may be important in the experiments, particularly involving cold alkali polar dimers.

The deoxyribonucleic acid of Micrococcus radiodurans

PubMed Central

Schein, Arnold H.

1966-01-01

The DNA of Micrococcus radiodurans was prepared by three methods. Although the recovery of DNA varied considerably, the percentage molar base ratios of the DNA from the three preparations were essentially the same: guanine, 33±2; adenine, 18±1; cytosine, 33±2; thymine, 17±1. Base compositions calculated from Tm values and from density in caesium chloride gradients also yielded guanine+cytosine contents of 66 and 68% of total bases respectively. No unusual bases were observed. The S20,w values were characteristic of high-molecular-weight DNA. Electron microscopy showed the purified DNA in long strands; occasionally these were coiled. Images(a)(b)(c)(d)(e)Fig. 1. PMID:16742439

Absolute frequency measurement of the ? optical clock transition in ? with an uncertainty of ? using a frequency link to international atomic time

NASA Astrophysics Data System (ADS)

Baynham, Charles F. A.; Godun, Rachel M.; Jones, Jonathan M.; King, Steven A.; Nisbet-Jones, Peter B. R.; Baynes, Fred; Rolland, Antoine; Baird, Patrick E. G.; Bongs, Kai; Gill, Patrick; Margolis, Helen S.

2018-03-01

The highly forbidden ? electric octupole transition in ? is a potential candidate for a redefinition of the SI second. We present a measurement of the absolute frequency of this optical transition, performed using a frequency link to International Atomic Time to provide traceability to the SI second. The ? optical frequency standard was operated for 76% of a 25-day period, with the absolute frequency measured to be 642 121 496 772 645.14(26) Hz. The fractional uncertainty of ? is comparable to that of the best previously reported measurement, which was made by a direct comparison to local caesium primary frequency standards.

The chemistry of gold as an anion.

PubMed

Jansen, Martin

2008-09-01

Due to relativistic and classical shell structure effects, the 6s orbital of gold is significantly contracted and energetically stabilized. This is reflected by a strikingly high electron affinity, and a distinct tendency to adopt negatively polarized valence states. This tutorial review focuses on the chemistry of gold as an anion, displaying the integral ionic charge number of 1-. Two synthetic approaches to compounds containing monoatomic gold anions have become available: (1) reacting elemental gold with molten caesium and an oxide, e.g. Cs2O; (2) metathesis reactions involving Au- dissolved in liquid ammonia. Both procedures have proven to be rather versatile. Aurides synthesized along these routes are surveyed, in particular with respect to their structures and bonding properties.

[Distribution of 137Cs, 90Sr and their chemical analogues in the components of an above-ground part of a pine in a quasi-equilibrium condition].

PubMed

Mamikhin, S V; Manakhov, D V; Shcheglov, A I

2014-01-01

The additional study of the distribution of radioactive isotopes of caesium and strontium and their chemical analogues in the above-ground components of pine in the remote from the accident period was carried out. The results of the research confirmed the existence of analogy in the distribution of these elements on the components of this type of wood vegetation in the quasi-equilibrium (relatively radionuclides) condition. Also shown is the selective possibility of using the data on the ash content of the components of forest stands of pine and oak as an information analogue.

First uncertainty evaluation of the FoCS-2 primary frequency standard

NASA Astrophysics Data System (ADS)

Jallageas, A.; Devenoges, L.; Petersen, M.; Morel, J.; Bernier, L. G.; Schenker, D.; Thomann, P.; Südmeyer, T.

2018-06-01

We report the uncertainty evaluation of the Swiss continuous primary frequency standard FoCS-2 (Fontaine Continue Suisse). Unlike other primary frequency standards which are working with clouds of cold atoms, this fountain uses a continuous beam of cold caesium atoms bringing a series of metrological advantages and specific techniques for the evaluation of the uncertainty budget. Recent improvements of FoCS-2 have made possible the evaluation of the frequency shifts and of their uncertainties in the order of . When operating in an optimal regime a relative frequency instability of is obtained. The relative standard uncertainty reported in this article, , is strongly dominated by the statistics of the frequency measurements.

High efficiency Raman memory by suppressing radiation trapping

NASA Astrophysics Data System (ADS)

Thomas, S. E.; Munns, J. H. D.; Kaczmarek, K. T.; Qiu, C.; Brecht, B.; Feizpour, A.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.; Saunders, D. J.

2017-06-01

Raman interactions in alkali vapours are used in applications such as atomic clocks, optical signal processing, generation of squeezed light and Raman quantum memories for temporal multiplexing. To achieve a strong interaction the alkali ensemble needs both a large optical depth and a high level of spin-polarisation. We implement a technique known as quenching using a molecular buffer gas which allows near-perfect spin-polarisation of over 99.5 % in caesium vapour at high optical depths of up to ˜ 2× {10}5; a factor of 4 higher than can be achieved without quenching. We use this system to explore efficient light storage with high gain in a GHz bandwidth Raman memory.

Weathering of radiocaesium contamination on urban streets, walls and roofs.

PubMed

Andersson, K G; Roed, J; Fogh, C L

2002-01-01

Recent investigations in Russia have emphasised the significance of dose contributions from contamination on urban streets and roof pavings, and, typically to a lesser extent, walls in the urban environment. The crucial factor determining the magnitude of these contributions is the retention of the contamination by the different types of urban surface. Since the Chernobyl accident, a series of long-term field studies has been carried out on urban streets, walls and roofs, to examine the weathering processes of 137Cs on the various surface types. The derived time-functions are applied to estimate resultant long-term doses to inhabitants of an urban centre. The paper highlights the effect on caesium retention of surface material characteristics.

Size scaling of negative hydrogen ion sources for fusion

NASA Astrophysics Data System (ADS)

Fantz, U.; Franzen, P.; Kraus, W.; Schiesko, L.; Wimmer, C.; Wünderlich, D.

2015-04-01

The RF-driven negative hydrogen ion source (H-, D-) for the international fusion experiment ITER has a width of 0.9 m and a height of 1.9 m and is based on a ⅛ scale prototype source being in operation at the IPP test facilities BATMAN and MANITU for many years. Among the challenges to meet the required parameters in a caesiated source at a source pressure of 0.3 Pa or less is the challenge in size scaling of a factor of eight. As an intermediate step a ½ scale ITER source went into operation at the IPP test facility ELISE with the first plasma in February 2013. The experience and results gained so far at ELISE allowed a size scaling study from the prototype source towards the ITER relevant size at ELISE, in which operational issues, physical aspects and the source performance is addressed, highlighting differences as well as similarities. The most ITER relevant results are: low pressure operation down to 0.2 Pa is possible without problems; the magnetic filter field created by a current in the plasma grid is sufficient to reduce the electron temperature below the target value of 1 eV and to reduce together with the bias applied between the differently shaped bias plate and the plasma grid the amount of co-extracted electrons. An asymmetry of the co-extracted electron currents in the two grid segments is measured, varying strongly with filter field and bias. Contrary to the prototype source, a dedicated plasma drift in vertical direction is not observed. As in the prototype source, the performance in deuterium is limited by the amount of co-extracted electrons in short as well as in long pulse operation. Caesium conditioning is much harder in deuterium than in hydrogen for which fast and reproducible conditioning is achieved. First estimates reveal a caesium consumption comparable to the one in the prototype source despite the large size.

Inverse modelling-based reconstruction of the Chernobyl source term available for long-range transport

NASA Astrophysics Data System (ADS)

Davoine, X.; Bocquet, M.

2007-03-01

The reconstruction of the Chernobyl accident source term has been previously carried out using core inventories, but also back and forth confrontations between model simulations and activity concentration or deposited activity measurements. The approach presented in this paper is based on inverse modelling techniques. It relies both on the activity concentration measurements and on the adjoint of a chemistry-transport model. The location of the release is assumed to be known, and one is looking for a source term available for long-range transport that depends both on time and altitude. The method relies on the maximum entropy on the mean principle and exploits source positivity. The inversion results are mainly sensitive to two tuning parameters, a mass scale and the scale of the prior errors in the inversion. To overcome this hardship, we resort to the statistical L-curve method to estimate balanced values for these two parameters. Once this is done, many of the retrieved features of the source are robust within a reasonable range of parameter values. Our results favour the acknowledged three-step scenario, with a strong initial release (26 to 27 April), followed by a weak emission period of four days (28 April-1 May) and again a release, longer but less intense than the initial one (2 May-6 May). The retrieved quantities of iodine-131, caesium-134 and caesium-137 that have been released are in good agreement with the latest reported estimations. Yet, a stronger apportionment of the total released activity is ascribed to the first period and less to the third one. Finer chronological details are obtained, such as a sequence of eruptive episodes in the first two days, likely related to the modulation of the boundary layer diurnal cycle. In addition, the first two-day release surges are found to have effectively reached an altitude up to the top of the domain (5000 m).

Revisiting the radionuclide atmospheric dispersion event of the Chernobyl disaster - modelling sensitivity and data assimilation

NASA Astrophysics Data System (ADS)

Roustan, Yelva; Duhanyan, Nora; Bocquet, Marc; Winiarek, Victor

2013-04-01

A sensitivity study of the numerical model, as well as, an inverse modelling approach applied to the atmospheric dispersion issues after the Chernobyl disaster are both presented in this paper. On the one hand, the robustness of the source term reconstruction through advanced data assimilation techniques was tested. On the other hand, the classical approaches for sensitivity analysis were enhanced by the use of an optimised forcing field which otherwise is known to be strongly uncertain. The POLYPHEMUS air quality system was used to perform the simulations of radionuclide dispersion. Activity concentrations in air and deposited to the ground of iodine-131, caesium-137 and caesium-134 were considered. The impact of the implemented parameterizations of the physical processes (dry and wet depositions, vertical turbulent diffusion), of the forcing fields (meteorology and source terms) and of the numerical configuration (horizontal resolution) were investigated for the sensitivity study of the model. A four dimensional variational scheme (4D-Var) based on the approximate adjoint of the chemistry transport model was used to invert the source term. The data assimilation is performed with measurements of activity concentrations in air extracted from the Radioactivity Environmental Monitoring (REM) database. For most of the investigated configurations (sensitivity study), the statistics to compare the model results to the field measurements as regards the concentrations in air are clearly improved while using a reconstructed source term. As regards the ground deposited concentrations, an improvement can only be seen in case of satisfactorily modelled episode. Through these studies, the source term and the meteorological fields are proved to have a major impact on the activity concentrations in air. These studies also reinforce the use of reconstructed source term instead of the usual estimated one. A more detailed parameterization of the deposition process seems also to be able to improve the simulation results. For deposited activities the results are more complex probably due to a strong sensitivity to some of the meteorological fields which remain quite uncertain.

Parameter uncertainty analysis of a biokinetic model of caesium

DOE PAGES

Li, W. B.; Klein, W.; Blanchardon, Eric; ...

2014-04-17

Parameter uncertainties for the biokinetic model of caesium (Cs) developed by Leggett et al. were inventoried and evaluated. The methods of parameter uncertainty analysis were used to assess the uncertainties of model predictions with the assumptions of model parameter uncertainties and distributions. Furthermore, the importance of individual model parameters was assessed by means of sensitivity analysis. The calculated uncertainties of model predictions were compared with human data of Cs measured in blood and in the whole body. It was found that propagating the derived uncertainties in model parameter values reproduced the range of bioassay data observed in human subjects atmore » different times after intake. The maximum ranges, expressed as uncertainty factors (UFs) (defined as a square root of ratio between 97.5th and 2.5th percentiles) of blood clearance, whole-body retention and urinary excretion of Cs predicted at earlier time after intake were, respectively: 1.5, 1.0 and 2.5 at the first day; 1.8, 1.1 and 2.4 at Day 10 and 1.8, 2.0 and 1.8 at Day 100; for the late times (1000 d) after intake, the UFs were increased to 43, 24 and 31, respectively. The model parameters of transfer rates between kidneys and blood, muscle and blood and the rate of transfer from kidneys to urinary bladder content are most influential to the blood clearance and to the whole-body retention of Cs. For the urinary excretion, the parameters of transfer rates from urinary bladder content to urine and from kidneys to urinary bladder content impact mostly. The implication and effect on the estimated equivalent and effective doses of the larger uncertainty of 43 in whole-body retention in the later time, say, after Day 500 will be explored in a successive work in the framework of EURADOS.« less

Radioactivity in Virgin Soils and Soils from Some Areas with Closed Uranium Mining Facilities in Bulgaria

NASA Astrophysics Data System (ADS)

Yordanova, I.; Staneva, D.; Misheva, L.; Bineva, Ts.; Banov, M.

2012-04-01

The soil radioecology is an important part of the environmental research in the country. Since the beginning of the 1970's regular monitoring of the content of different radionuclides in Bulgarian soils has been done. Objective of the studies were virgin soils from high mountain areas, hills and plains (the region of Kozloduy NPP and the Danube river valley). Natural and men-made radionuclides were observed. In the 25-year period after the the contamination with radionuclides due to the 1986 Chernobyl NPP accident a rich data base has been collected, recording the radiation status of the soils in Bulgaria. Special attention has been paid to the contamination with the long-lived technogenic radionuclides caesium-137 and strontium-90. This paper presents a summary of the obtained results. Caesium-137 and strontium-90 were the main men-made radionuclides detected in the examined Bulgarian soils few years after the Chernobyl NPP accident. Their content in the soils from high mountain areas (Rodopa and Rila mountains) is several times higher than that in the soils from North Bulgaria and Sofia fields. High non-homogenity in the pollution within small areas (even as small as several square meters) has been observed. Natural radioactivity was also studied. Averaged values for natural radionuclides like uranium-238, thorium-232, and radium-226 in virgin soils from different areas in the country are presented. A comparison of the dynamics of their behavior throughout the years is done. Bulgaria is a country with intensive uranium mining activities in the past years. That is why radiological monitoring of closed uranium mining facilities in different regions of the country are obligatory and of great interest. This work presents results from such investigations made in regions where remediation has been done. The results have been evaluated according to the Bulgarian radionuclide environment contamination legislation. The necessity of permanent environmental monitoring is assessed.

An assessment of the radiological impact of the Windscale reactor fire, October 1957.

PubMed

Crick, M J; Linsley, G S

1984-11-01

On the 10th and 11 October 1957 a fire in the No 1 Pile at the Windscale establishment in Cumbria led to an uncontrolled release of activity to the atmosphere. The resultant cloud subsequently dispersed and radionuclides could be detected over England, Wales and parts of northern Europe. The extensive environmental measurements which were made during and after the release enabled a fairly accurate estimate to be made of the radiation doses to the most exposed individuals in the local population. Until recently, no estimates of the population dose resulting from the release had been published. This paper describes assessments which have been made by the NRPB of the population or collective dose from the release and of the possible associated health impact. In addition to the fission products that escaped, radionuclides were released from materials undergoing irradiation in the pile at the time of the fire. The assessment has included the results of a review of previously unpublished data which established the quantity of these nuclides released and considers their impact on both individual and population doses. The collective effective dose equivalent commitment from the release is estimated to have been 2.0 x 10(3) man Sv. The route of exposure which contributed the most to the collective dose was the inhalation pathway. Iodine-131 was the most important radionuclide, contributing nearly all of the collective dose to the thyroid and a large part of the collective effective dose. Polonium-210 and caesium-137 also made significant contributions; that from caesium-137 came in the longer term via external irradiation from ground deposits and the ingestion of contaminated foodstuffs. The methodology used in the study has been validated to a certain degree by comparing the predicted levels of individual thyroid activity and those measured directly in the weeks following the accident in London, Leeds and Cumbria.

Body concentration of caesium-137 in patients from Western Isles of Scotland.

PubMed Central

Isles, C G; Robertson, I; Macleod, J A; Preston, T; East, B W; Hole, D J; Lever, A F

1991-01-01

OBJECTIVES--To compare caesium-137 concentrations in patients from the Western Isles Health Board, Glasgow area, and other parts of the Scottish mainland, and to investigate the source of 137Cs in patients from the Western Isles. DESIGN--Study of hypertensive patients having electrolyte concentrations measured, including 137Cs. Interview by questionnaire of island subjects about intake of foods likely to contain radiocaesium and the source of these foods. Measurement of 137Cs and 134Cs in food, urine, and vegetation. SETTING--Scottish mainland and Western Isles, 1979-86. All measurements before Chernobyl nuclear accident. PATIENTS--413 consecutive patients referred to the blood pressure unit for investigation of hypertension. 60 from the Western Isles, including 44 from North Uist; 32 from North Uist participated in the dietary analysis. MAIN OUTCOME MEASURES--Concentration of radiocaesium in the body, urine, food, and vegetation. Islanders' consumption of local produce. RESULTS--Patients from the Western Isles had five times higher body concentrations of 137Cs (median 2.54 (interquartile range 1.25-3.73)) Bq/gK) than did patients from around Glasgow (0.47 (0.26-0.66) Bq/gK) and other parts of the Scottish mainland (0.42 (0.24-0.71) Bq/gK). Islanders often consumed local milk and mutton, but ate local fish rarely. 137Cs and 134Cs were present in coastal (21.6 Bq/kg 137Cs, 0.25 Bq/kg 134Cs) and moorland (135.9, 0.65 Bq/kg) grasses and in islanders' urine (2.01, 0.013 Bq/l). Lower concentrations (0.336, 0.004 Bq/l), were found in the urine of Glasgow controls (p less than 0.001 for both isotopes). CONCLUSIONS--Islanders have excess body 137Cs concentrations, most of which probably comes from local milk and lamb. The radioactivity is not above the recommended safety limit. The presence of 134Cs suggests that nuclear reprocessing is the source of some of the radiocaesium. PMID:1906765

Distribution of Natural (U-238, Th-232, Ra-226) and Technogenic (Sr-90, Cs-137) Radionuclides in Soil-Plants Complex Near Issyk-Kul Lake, Kyrgyzstan

NASA Astrophysics Data System (ADS)

Jovanovic, L.; Kaldybaev, B.; Djenbaev, B.; Tilenbaev, A.

2012-04-01

Researches on radionuclides distribution in the soil-plants complex provide essential information in understanding human exposure to natural and technogenic sources of radiation. It is necessary in establishing regulation relating to radiation protection. The aim of this study was the radiochemical analysis of the content natural radionuclides 238U, 232Th,226Ra and technogenic radionuclides content (90Sr, 137Cs) in soils near Issyk-Kul lake (Kyrgyzstan). Results of radiochemical analyses have shown, that the concentrations of thorium-232 are fluctuating in the limits (11.7-84.1)-10-4% in the soils. The greatest concentration of thorium-232 has been found in the light chestnut soils. The content of uranium-238 in the soils near Issyk-Kul lake is fluctuating from 2.8 up to 12.7-10-4%. Radium-226 has more migration ability in comparison with other heavy natural radionuclides. According to our research the concentrations of radium-226 are fluctuating in the limits (9.4-43.0)-10-11%. The greatest concentration of radium-226 (43,0±2,8)-10-11% has been determined in the light chestnut soil. In connection with global migration of contaminating substances, including radioactive, the special attention is given long-lived radionuclides strontium-90 and caesium-137 in food-chains, and agroecosystems. Results of radiochemical analyses have shown, that specific activity of strontium-90 is fluctuating in the range of 2.9 up to 11.1 Bq/kg, and caesium-137 from 3.7 up to 14,3 Bq/kg in the soil of agroecosystems in the region of Issyk-Kul. In soil samples down to 1 meter we have observed vertical migration of these radionuclides, they were found to accumulate on the surface of soil horizon (0-5 cm) and their specific activity sharply decreases with depth. In addition in high-mountain pastures characterized by horizontal migration of cattle in profiles of soil, it was discovered that specific activity of radionuclides are lower on the slope than at the foot of the mountain. The content of natural radionuclides (238U, 232Th, 226Ra ) and technogenic radionuclides (90Sr, 137Cs) in the soils depend on many factors: the type and mechanical composition of soil, capacity of absorption, acidity, concentration of exchange forms of carbonates, organic substances. The radionuclides accumulation process in the plants depend on a specific accumulation ability of plants. During the researches it has been found that radionuclides accumulate in vegetative organs more than in reproductive parts of plants. According to the accumulation degrees of natural radionuclides plants taking place in the following decreasing series: sugar beet > potatoes > lucerne > clover > oats > perennial herbs > wheat > annual grass crops > barley > corn. Radiochemical analysis of the technogenic radionuclides in the plants has been determined that specific activity of strontium-90 is increased in leguminous plants (cobs of corn, lucerne) in comparison with other cultures. Caesium-137 is accumulated in beet roots, cobs of corn and lucerne. Key words: natural radionuclides, technogenic radionuclides, soil-plants complex, Issyk-Kul lake, Kyrgyzstan

First results of the ITER-relevant negative ion beam test facility ELISE (invited).

PubMed

Fantz, U; Franzen, P; Heinemann, B; Wünderlich, D

2014-02-01

An important step in the European R&D roadmap towards the neutral beam heating systems of ITER is the new test facility ELISE (Extraction from a Large Ion Source Experiment) for large-scale extraction from a half-size ITER RF source. The test facility was constructed in the last years at Max-Planck-Institut für Plasmaphysik Garching and is now operational. ELISE is gaining early experience of the performance and operation of large RF-driven negative hydrogen ion sources with plasma illumination of a source area of 1 × 0.9 m(2) and an extraction area of 0.1 m(2) using 640 apertures. First results in volume operation, i.e., without caesium seeding, are presented.

The impact of agricultural soil erosion on the global carbon cycle

USGS Publications Warehouse

Van Oost, Kristof; Quine, T.A.; Govers, G.; De Gryze, S.; Six, J.; Harden, J.W.; Ritchie, J.C.; McCarty, G.W.; Heckrath, G.; Kosmas, C.; Giraldez, J.V.; Marques Da Silva, J.R.; Merckx, R.

2007-01-01

Agricultural soil erosion is thought to perturb the global carbon cycle, but estimates of its effect range from a source of 1 petagram per year -1 to a sink of the same magnitude. By using caesium-137 and carbon inventory measurements from a large-scale survey, we found consistent evidence for an erosion-induced sink of atmospheric carbon equivalent to approximately 26% of the carbon transported by erosion. Based on this relationship, we estimated a global carbon sink of 0.12 (range 0.06 to 0.27) petagrams of carbon per year-1 resulting from erosion in the world's agricultural landscapes. Our analysis directly challenges the view that agricultural erosion represents an important source or sink for atmospheric CO2.

Plastic optical fibre sensor for in-vivo radiation monitoring during brachytherapy

NASA Astrophysics Data System (ADS)

Woulfe, P.; Sullivan, F. J.; Lewis, E.; O'Keeffe, S.

2015-09-01

An optical fibre sensor is presented for applications in real-time in-vivo monitoring of the radiation dose a cancer patient receives during seed implantation in Brachytherapy. The sensor is based on radioluminescence whereby radiation sensitive scintillation material is embedded in the core of a 1mm plastic optical fibre. Three scintillation materials are investigated: thallium-doped caesium iodide (CsI:Tl), terbium-doped gadolinium oxysulphide (Gd2O2S:Tb) and europium-doped lanthanum oxysulphide (La2O2S:Eu). Terbium-doped gadolinium oxysulphide was identified as being the most suitable scintillator and further testing demonstrates its measureable response to different activities of Iodine-125, the radio-active source commonly used in Brachytherapy for treating prostate cancer.

The uptake of plutonium-238, 239, 240, americium-241, strontium-90 and caesium-137 into potatoes.

PubMed

Popplewell, D S; Ham, G J; Johnson, T E; Stather, J W; Sumner, S A

1984-09-01

Transfer factors have been measured for 239 Pu + 240 Pu, 241 Am, 90 Sr and 137 Cs into potatoes grown in a blend of soil which included silt polluted with radioactive waste discharged into the Irish Sea. The experiment has been carried out over four seasons and attempts to assess the radiological consequences to the consumer which would arise if potatoes were to be grown in land heavily contaminated with the silt. During the course of the experiment plutonium and americium became less available for uptake, 90 Sr became slightly more available and 137 Cs remained nearly constant in its availability. The values of the transfer factors are among the lowest reported for these radionuclides into potatoes.

[Radioactive caesium contamination in Inago and sustainability of Inago cuisine in Fukushima].

PubMed

Mitsuhashi, Ryota; Mizuno, Hiroshi; Saeki, Shinjiro; Uchiyama, Sho-ichi; Yoshida, Makoto; Takamatsu, Yuki; Fugo, Hajime

2013-01-01

Inago (edible grasshoppers, Oxya spp.) was a popular food in the Fukushima area, before the reactor accident at Fukushima Dai-ichi Nuclear Power Station in March 2011. We investigated the radioactivity of Cs-134 and Cs-137 contained in Inago captured in Sukagawa, Motomiya, Inawashiro, Date, and Iidate in Fukushima prefecture in 2011 and 2012. The maximum combined radioactivity of Cs-134 and Cs-137 in Inago was 60.7 Bq/kg, which is below the maximum permitted level (100 Bq/kg) in foods established by the government of Japan in April 2012. Furthermore, conventional cooking processes decreased the radioactivity in cooked Inago to under 15.8 Bq/kg, a quarter of that in uncooked Inago. Therefore, we concluded that the health risk of eating Inago is low.

The effect of lithium and related metal ions on the urinary excretion of 2-oxoglutarate and citrate in the rat

PubMed Central

Bond, P.A.; Jenner, F.A.

1974-01-01

1 Administration of lithium ions to rats, either acutely by intraperitoneal injection or chronically in food, causes increased excretion of 2-oxoglutarate and citrate. 2 Chronic administration in food of rubidium and caesium causes decreased excretion of 2-oxoglutarate and citrate. 3 The effects described are not due to changes in urine volume, nor pH, nor are they simply related to the excretion of the injected ion. 4 Acute administration of lithium caused an increased level of 2-oxoglutarate in kidney and reduced the ratio of glutamate to 2-oxoglutarate. 5 Renal gluconeogenesis in slices was only slightly affected by either acute administration of lithium to the animals or by its presence in the incubation medium of renal slices. PMID:4425767

A case study of the long-term retention of 137Cs after inhalation of high temperature reactor fuel element ash.

PubMed

Froning, M; Kozielewski, T; Schläger, M; Hill, P

2004-01-01

In 1987, a worker was internally contaminated with 137Cs as a result of an accident during the handling of high temperature reactor fuel element ash. In the long-term follow-up monitoring an unusual retention behaviour was found. The observed time dependence of caesium retention does not agree with the standard models of ICRP Publication 30. The present case can be better explained by assuming an intake of a mixture of type F and type S compounds. However, experimental data can be best described by a four-exponential retention function with two long-lived components, which was used as an ad hoc model for dose calculation. The resulting dose is compared with doses calculated on the basis of ICRP Publication 66.

Simulation of ¹³⁷Cs transport and deposition after the Chernobyl Nuclear Power Plant accident and radiological doses over the Anatolian peninsula.

PubMed

Simsek, V; Pozzoli, L; Unal, A; Kindap, T; Karaca, M

2014-11-15

The Chernobyl Nuclear Power Plant (CNPP) accident occurred on April 26 of 1986, it is still an episode of interest, due to the large amount of radionuclides dispersed in the atmosphere. Caesium-137 ((137)Cs) is one of the main radionuclides emitted during the Chernobyl accident, with a half-life of 30years, which can be accumulated in humans and animals, and for this reason the impacts on population are still monitored today. One of the main parameters in order to estimate the exposure of population to (137)Cs is the concentration in the air, during the days after the accident, and the deposition at surface. The transport and deposition of (137)Cs over Europe occurred after the CNPP accident has been simulated using the WRF-HYSPLIT modeling system. Four different vertical and temporal emission rate profiles have been simulated, as well as two different dry deposition velocities. The model simulations could reproduce fairly well the observations of (137)Cs concentrations and deposition, which were used to generate the 'Atlas of Caesium deposition on Europe after the Chernobyl accident' and published in 1998. An additional focus was given on (137)Cs deposition and air concentrations over Turkey, which was one of the main affected countries, but not included in the results of the Atlas. We estimated a total deposition of 2-3.5 PBq over Turkey, with 2 main regions affected, East Turkey and Central Black Sea coast until Central Anatolia, with values between 10 kBq m(-2) and 100 kBq m(-2). Mean radiological effective doses from simulated air concentrations and deposition has been estimated for Turkey reaching 0.15 mSv/year in the North Eastern part of Turkey, even if the contribution from ingestion of contaminated food and water is not considered, the estimated levels are largely below the 1 mSv limit indicated by the International Commission on Radiological Protection. Copyright © 2014 Elsevier B.V. All rights reserved.

Modelling the dynamics of ambient dose rates induced by radiocaesium in the Fukushima terrestrial environment

NASA Astrophysics Data System (ADS)

Gonze, Marc-André; Mourlon, Christophe; Calmon, Philippe; Manach, Erwan; Debayle, Christophe; Baccou, Jean

2017-09-01

Since the Fukushima accident, Japanese scientists have been intensively monitoring ambient radiations in the highly contaminated territories situated within 80 km of the nuclear site. The surveys that were conducted through mainly carborne, airborne and in situ gamma-ray measurement devices, enabled to efficiently characterize the spatial distribution and temporal evolution of air dose rates induced by Caesium-134 and Caesium-137 in the terrestrial systems. These measurements revealed that radiation levels decreased at rates greater than expected from physical decay in 2011-2012 (up to a factor of 2), and dependent on the type of environment (i.e. urban, agricultural or forest). Unlike carborne measurements that may have been strongly influenced by the depuration of road surfaces, no obvious reason can be invoked for airborne measurements, especially above forests that are known to efficiently retain and recycle radiocaesium. The purpose of our research project is to develop a comprehensive understanding of the data acquired by Japanese, and identify the environmental mechanisms or factors that may explain such decays. The methodology relies on the use of a process-based and spatially-distributed dynamic model that predicts radiocaesium transfer and associated air dose rates inside/above a terrestrial environment (e.g., forests, croplands, meadows, bare soils and urban areas). Despite the lack of site-specific data, our numerical study predicts decrease rates that are globally consistent with both aerial and in situ observations. The simulation at a flying altitude of 200 m indicated that ambient radiation levels decreased over the first 12 months by about 45% over dense urban areas, 15% above evergreen coniferous forests and between 2 and 12% above agricultural lands, owing to environmental processes that are identified and discussed. In particular, we demonstrate that the decrease over evergreen coniferous regions might be due the combined effects of canopy depuration (through biological and physical mechanisms) and the shielding of gamma rays emitted from the forest floor by vegetation. Our study finally suggests that airborne surveys might have not reflected dose rates at ground level in forest systems, which were predicted to slightly increase by 5 to 10% during the same period of time.

Optimization of exposure and countryside waste management for different accidental radioactive release

NASA Astrophysics Data System (ADS)

Guétat, Philippe

2017-09-01

Since the Fukushima accident, Japanese scientists have been intensively monitoring ambient radiations in the highly contaminated territories situated within 80 km of the nuclear site. The surveys that were conducted through mainly carborne, airborne and in situ gamma-ray measurement devices, enabled to efficiently characterize the spatial distribution and temporal evolution of air dose rates induced by Caesium-134 and Caesium-137 in the terrestrial systems. These measurements revealed that radiation levels decreased at rates greater than expected from physical decay in 2011-2012 (up to a factor of 2), and dependent on the type of environment (i.e. urban, agricultural or forest). Unlike carborne measurements that may have been strongly influenced by the depuration of road surfaces, no obvious reason can be invoked for airborne measurements, especially above forests that are known to efficiently retain and recycle radiocaesium. The purpose of our research project is to develop a comprehensive understanding of the data acquired by Japanese, and identify the environmental mechanisms or factors that may explain such decays. The methodology relies on the use of a process-based and spatially-distributed dynamic model that predicts radiocaesium transfer and associated air dose rates inside/above a terrestrial environment (e.g., forests, croplands, meadows, bare soils and urban areas). Despite the lack of site-specific data, our numerical study predicts decrease rates that are globally consistent with both aerial and in situ observations. The simulation at a flying altitude of 200 m indicated that ambient radiation levels decreased over the first 12 months by about 45% over dense urban areas, 15% above evergreen coniferous forests and between 2 and 12% above agricultural lands, owing to environmental processes that are identified and discussed. In particular, we demonstrate that the decrease over evergreen coniferous regions might be due the combined effects of canopy depuration (through biological and physical mechanisms) and the shielding of gamma rays emitted from the forest floor by vegetation. Our study finally suggests that airborne surveys might have not reflected dose rates at ground level in forest systems, which were predicted to slightly increase by 5 to 10% during the same period of time.

The application of Caesium-137 and Plutonium-239+240 measurements to investigate floodplain deposition in a semi-arid, low-fallout environment

NASA Astrophysics Data System (ADS)

Amos, K. J.; Croke, J. C.; Timmers, H.; Owens, P. N.

2009-04-01

Floodplains comprise geomorphologically important sources and sinks for sediments and associated pollutants, yet the sedimentology of large dryland floodplains is not well understood. Processes occurring on such floodplains are often difficult to observe, and techniques used to investigate smaller perennial floodplains are often not practical in these environments. This study assesses the utility of Cs-137 inventory and depth-profile techniques for determining relative amounts of floodplain sedimentation in the Fitzroy River, north-eastern Australia; a 143 000 km2 semi-arid river system. Caesium-137 inventories were calculated for floodplain and reference location bulk soil cores collected from four sites. Depth profiles of Cs-137 concentration from each floodplain site and a reference location were recorded. The areal density of Cs-137 at reference locations ranged from 13-978 Bq m-2 (0-1367 Bq m-2 at the 95% confidence interval), and the mean value ± 2(standard error of the mean) was 436±264 Bq m-2, similar to published data from other southern hemisphere locations. Floodplain inventories ranged from 68-1142 Bq m-2 (0-1692 Bq m-2 at the 95% confidence interval), essentially falling within the range of reference inventory values, thus preventing calculation of erosion or deposition. Depth-profiles of Cs-137 concentration indicate erosion at one site and over 66 cm of deposition at another since 1954. Analysis of 239+240Pu concentrations in a depositional core substantiated the interpretation made from Cs-137 data, and depict a more tightly constrained peak in concentration. Average annual deposition rates range from 0-15 mm. The similarity between floodplain and reference bulk inventories does not necessarily indicate a lack of erosion or deposition, due to low Cs-137 fallout in the region and associated high measurement uncertainties, and a likely influence of gully and bank eroded sediments with no or limited adsorbed Cs-137. In this low-fallout environment, detailed depth-profile data are necessary for investigating sedimentation using Cs-137.

Prediction of the effects of soil-based countermeasures on soil solution chemistry of soils contaminated with radiocesium using the hydrogeochemical code PHREEQC.

PubMed

Hormann, Volker; Kirchner, Gerald

2002-04-22

For agriculturally used areas, which are contaminated by the debris from a nuclear accident, the use of chemical amendmends (e.g. potassium chloride and lime) is among the most common soil-based countermeasures. These countermeasures are intended to reduce the plant uptake of radionuclides (mainly 137Cs and 90Sr) by competitive inhibition by chemically similar ions. So far, the impacts of countermeasures on soil solution composition - and thus, their effectiveness - have almost exclusively been established experimentally, since they depend on mineral composition and chemical characteristics of the soil affected. In this study, which focuses on caesium contamination, the well-established code PHREEQC was used as a geochemical model to calculate the changes in the ionic compositions of soil solutions, which result from the application of potassium or ammonium in batch equilibrium experiments. The simple ion exchange model used by PHREEQC was improved by taking into account selective sorption of Cs+, NH4+ and K+ by clay minerals. Calculations were performed with three different initial soil solution compositions, corresponding to particular soil types (loam, sand, peat). For loamy and sandy soils, our calculational results agree well with experimental data reported by Nisbet (Effectiveness of soil-based countermeasures six months and one year after contamination of five diverse soil types with caesium-134 and strontium-90. Contract Report NRPB-M546, National Radiation Protection Board, Chilton, 1995.). For peat, discrepancies were found indicating that for organic soils a reliable set of exchange constants of the relevant cations still has to be determined experimentally. For cesium, however, these discrepancies almost disappeared if selective sites were assumed to be inaccessible. Additionally, results of sensitivity analyses are presented by which the influence of the main soil parameters on Cs+ concentrations in solution after soil treatment has been systematically studied. It is shown that calculating the impacts of soil-based chemical countermeasures on soil solution chemistry using geochemical codes such as PHREEQC offers an attractive alternative to establishing these impacts by often time-consuming and site-specific experiments.

On the influence of ion exchange on the local structure of the titanosilicate ETS-10.

PubMed

Pavel, Claudiu C; Zibrowius, Bodo; Löffler, Elke; Schmidt, Wolfgang

2007-07-14

The effect of ion exchange with different monovalent cations (NH(4)(+), K(+), Na(+) and Cs(+)) on the local structure of the titanosilicate ETS-10 has been studied by (29)Si MAS NMR and Raman spectroscopy. Although X-ray diffraction shows no significant influence of ion exchange on the long range order, ammonium exchange is found to result in substantial damage to the local structure. Ion exchange experiments with alkali cations under significantly more acidic conditions clearly show that the structural damage brought about by ammonium exchange is not caused by the low pH of the exchange solution. The exchange with potassium and caesium ions also leads to significant changes in the (29)Si NMR and Raman spectra. However, these changes can largely be reversed by sodium back-exchange.

ACES MWL data analysis center at SYRTE

NASA Astrophysics Data System (ADS)

Meynadier, F.; Delva, P.; le Poncin-Lafitte, C.; Guerlin, C.; Laurent, P.; Wolf, P.

2017-12-01

The ACES-PHARAO mission aims at operating a cold-atom caesium clock on board the International Space Station, and performs two-way time transfer with ground terminals, in order to allow highly accurate and stable comparisons of its internal timescale with those found in various metrology institutes. Scientific goals in fundamental physics include tests of the gravitational redshift with unprecedented accuracy, and search for a violation of the Lorentz local invariance. As launch is coming closer we are getting ready to process the data expected to come from ACES Microwave Link (MWL) once on board the International Space Station. Several hurdles have been cleared in our software in the past months, as we managed to implement algorithms that reach target accuracy for ground/space desynchronisation measurement. I will present the current status of data analysis preparation, as well as the activities that will take place at SYRTE in order to set up its data processing center.

Radioactivity from Fukushima Dai-ichi in air over Europe; part 2: what can it tell us about the accident?

PubMed

Kirchner, G; Bossew, P; De Cort, M

2012-12-01

It is shown which information can be extracted from the monitoring of radionuclides emitted from the Fukushima Dai-ichi nuclear power plant and transported to Europe. In this part the focus will be on the analysis of the concentration ratios. While (131)I, (134)Cs and (137)Cs were reported by most stations, other detected radionuclides, reported by some, are (95)Nb, (129m)Te, (132)Te, (132)I, (136)Cs and (140)La. From their activity ratios a mean burn-up of 26.7 GWd/t of the fuel from which they originated is estimated. Based on these data, inventories of radionuclides present at the time of the accident are calculated. The caesium activity ratios indicate emissions from the core of unit 4 which had been unloaded into the fuel storage pool prior to the accident. Copyright © 2011 Elsevier Ltd. All rights reserved.

Thermochromic halide perovskite solar cells.

PubMed

Lin, Jia; Lai, Minliang; Dou, Letian; Kley, Christopher S; Chen, Hong; Peng, Fei; Sun, Junliang; Lu, Dylan; Hawks, Steven A; Xie, Chenlu; Cui, Fan; Alivisatos, A Paul; Limmer, David T; Yang, Peidong

2018-03-01

Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Here, we demonstrate a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply coloured perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colours and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. We demonstrate excellent device stability over repeated phase transition cycles without colour fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies.

Thermochromic halide perovskite solar cells

NASA Astrophysics Data System (ADS)

Lin, Jia; Lai, Minliang; Dou, Letian; Kley, Christopher S.; Chen, Hong; Peng, Fei; Sun, Junliang; Lu, Dylan; Hawks, Steven A.; Xie, Chenlu; Cui, Fan; Alivisatos, A. Paul; Limmer, David T.; Yang, Peidong

2018-03-01

Smart photovoltaic windows represent a promising green technology featuring tunable transparency and electrical power generation under external stimuli to control the light transmission and manage the solar energy. Here, we demonstrate a thermochromic solar cell for smart photovoltaic window applications utilizing the structural phase transitions in inorganic halide perovskite caesium lead iodide/bromide. The solar cells undergo thermally-driven, moisture-mediated reversible transitions between a transparent non-perovskite phase (81.7% visible transparency) with low power output and a deeply coloured perovskite phase (35.4% visible transparency) with high power output. The inorganic perovskites exhibit tunable colours and transparencies, a peak device efficiency above 7%, and a phase transition temperature as low as 105 °C. We demonstrate excellent device stability over repeated phase transition cycles without colour fade or performance degradation. The photovoltaic windows showing both photoactivity and thermochromic features represent key stepping-stones for integration with buildings, automobiles, information displays, and potentially many other technologies.

Strategy to overcome recombination limited photocurrent generation in CsPbX3 nanocrystal arrays

NASA Astrophysics Data System (ADS)

Mir, Wasim J.; Livache, Clément; Goubet, Nicolas; Martinez, Bertille; Jagtap, Amardeep; Chu, Audrey; Coutard, Nathan; Cruguel, Hervé; Barisien, Thierry; Ithurria, Sandrine; Nag, Angshuman; Dubertret, Benoit; Ouerghi, Abdelkarim; Silly, Mathieu G.; Lhuillier, Emmanuel

2018-03-01

We discuss the transport properties of CsPbBrxI3-x perovskite nanocrystal arrays as a model ensemble system of caesium lead halide-based perovskite nanocrystal arrays. While this material is very promising for the design of light emitting diodes, laser, and solar cells, very little work has been devoted to the basic understanding of their (photo)conductive properties in an ensemble system. By combining DC and time-resolved photocurrent measurements, we demonstrate fast photodetection with time response below 2 ns. The photocurrent generation in perovskite nanocrystal-based arrays is limited by fast bimolecular recombination of the material, which limits the lifetime of the photogenerated electron-hole pairs. We propose to use nanotrench electrodes as a strategy to ensure that the device size fits within the obtained diffusion length of the material in order to boost the transport efficiency and thus observe an enhancement of the photoresponse by a factor of 1000.

Strontium-90 and caesium-137 activity concentrations in bats in the Chernobyl exclusion zone.

PubMed

Gashchak, Sergey; Beresford, Nicholas Anthony; Maksimenko, Andrey; Vlaschenko, Anton S

2010-11-01

Bats are a protected species and as such may be an object of protection in radiological assessments of the environment. However, there have previously been only few radioecological studies of species of bats. In this paper, results for >140 measurements of (90)Sr and (137)Cs in 10 species of bats collected within the Chernobyl zone are presented. There was some indication of a decreasing transfer of (90)Sr with increasing deposition, although this was inconsistent across species and explained little of the observed variability. There was no difference between male and female bats in the transfer (expressed as the ratio of whole-body activity concentrations to those in soil) of either radionuclide. There was considerable variability in transfer across all species groups. At two sites where there were sufficient data, Eptesicus serotinus was found to have higher transfer than other species.

Progress in understanding fission-product behaviour in coated uranium-dioxide fuel particles

NASA Astrophysics Data System (ADS)

Barrachin, M.; Dubourg, R.; Kissane, M. P.; Ozrin, V.

2009-03-01

Supported by results of calculations performed with two analytical tools (MFPR, which takes account of physical and chemical mechanisms in calculating the chemical forms and physical locations of fission products in UO2, and MEPHISTA, a thermodynamic database), this paper presents an investigation of some important aspects of the fuel microstructure and chemical evolutions of irradiated TRISO particles. The following main conclusions can be identified with respect to irradiated TRISO fuel: first, the relatively low oxygen potential within the fuel particles with respect to PWR fuel leads to chemical speciation that is not typical of PWR fuels, e.g., the relatively volatile behaviour of barium; secondly, the safety-critical fission-product caesium is released from the urania kernel but the buffer and pyrolytic-carbon coatings could form an important chemical barrier to further migration (i.e., formation of carbides). Finally, significant releases of fission gases from the urania kernel are expected even in nominal conditions.

Radionuclide monitoring in Northern Ireland of the Chernobyl nuclear reactor accident

PubMed Central

Gilmore, B J; Cranley, K

1987-01-01

Northern Ireland received higher radiation doses due to the radionuclide contamination from the Chernobyl nuclear reactor accident than did the south of England. Levels of radioactive iodine (131I) and caesium (137Cs) in cows' milk in Northern Ireland increased to 166 and 120 Bq/l respectively in May 1986, but had decreased by factors of one million, and of twenty-five, respectively, by 1 September 1986. The resultant radiation doses represent less than one per cent of those received by a Northern Ireland individual over a period of 40 years from natural background radiation sources. The added risk to any individual from the Chernobyl accident will therefore be very small and may best be judged in the context of the enormously greater risk of death due to potentially preventable diseases, such as smoking-related lung cancer, and coronary heart disease. PMID:3590387

Modelling the dynamics of ambient dose rates induced by radiocaesium in the Fukushima terrestrial environment.

PubMed

Gonze, Marc-André; Mourlon, Christophe; Calmon, Philippe; Manach, Erwan; Debayle, Christophe; Baccou, Jean

2016-09-01

Since the Fukushima accident, Japanese scientists have been intensively monitoring ambient radiations in the highly contaminated territories situated within 80 km of the nuclear site. The surveys that were conducted through mainly carborne, airborne and in situ gamma-ray measurement devices, enabled to efficiently characterize the spatial distribution and temporal evolution of air dose rates induced by Caesium-134 and Caesium-137 in the terrestrial systems. These measurements revealed that radiation levels decreased at rates greater than expected from physical decay in 2011-2012 (up to a factor of 2), and dependent on the type of environment (i.e. urban, agricultural or forest). Unlike carborne measurements that may have been strongly influenced by the depuration of road surfaces, no obvious reason can be invoked for airborne measurements, especially above forests that are known to efficiently retain and recycle radiocaesium. The purpose of our research project is to develop a comprehensive understanding of the data acquired by Japanese, and identify the environmental mechanisms or factors that may explain such decays. The methodology relies on the use of a process-based and spatially-distributed dynamic model that predicts radiocaesium transfer and associated air dose rates inside/above a terrestrial environment (e.g., forests, croplands, meadows, bare soils and urban areas). Despite the lack of site-specific data, our numerical study predicts decrease rates that are globally consistent with both aerial and in situ observations. The simulation at a flying altitude of 200 m indicated that ambient radiation levels decreased over the first 12 months by about 45% over dense urban areas, 15% above evergreen coniferous forests and between 2 and 12% above agricultural lands, owing to environmental processes that are identified and discussed. In particular, we demonstrate that the decrease over evergreen coniferous regions might be due the combined effects of canopy depuration (through biological and physical mechanisms) and the shielding of gamma rays emitted from the forest floor by vegetation. Our study finally suggests that airborne surveys might have not reflected dose rates at ground level in forest systems, which were predicted to slightly increase by 5-10% during the same period of time. Copyright © 2015 Elsevier Ltd. All rights reserved.

An updated computational model of rabbit sinoatrial action potential to investigate the mechanisms of heart rate modulation

PubMed Central

Severi, Stefano; Fantini, Matteo; Charawi, Lara A; DiFrancesco, Dario

2012-01-01

The cellular basis of cardiac pacemaking is still debated. Reliable computational models of the sinoatrial node (SAN) action potential (AP) may help gain a deeper understanding of the phenomenon. Recently, novel models incorporating detailed Ca2+-handling dynamics have been proposed, but they fail to reproduce a number of experimental data, and more specifically effects of ‘funny’ (If) current modifications. We therefore developed a SAN AP model, based on available experimental data, in an attempt to reproduce physiological and pharmacological heart rate modulation. Cell compartmentalization and intracellular Ca2+-handling mechanisms were formulated as in the Maltsev–Lakatta model, focusing on Ca2+-cycling processes. Membrane current equations were revised on the basis of published experimental data. Modifications of the formulation of currents/pumps/exchangers to simulate If blockers, autonomic modulators and Ca2+-dependent mechanisms (ivabradine, caesium, acetylcholine, isoprenaline, BAPTA) were derived from experimental data. The model generates AP waveforms typical of rabbit SAN cells, whose parameters fall within the experimental ranges: 352 ms cycle length, 80 mV AP amplitude, −58 mV maximum diastolic potential (MDP), 108 ms APD50, and 7.1 V s−1 maximum upstroke velocity. Rate modulation by If-blocking drugs agrees with experimental findings: 20% and 22% caesium-induced (5 mm) and ivabradine-induced (3 μm) rate reductions, respectively, due to changes in diastolic depolarization (DD) slope, with no changes in either MDP or take-off potential (TOP). The model consistently reproduces the effects of autonomic modulation: 20% rate decrease with 10 nm acetylcholine and 28% increase with 1 μm isoprenaline, again entirely due to increase in the DD slope, with no changes in either MDP or TOP. Model testing of BAPTA effects showed slowing of rate, −26%, without cessation of beating. Our up-to-date model describes satisfactorily experimental data concerning autonomic stimulation, funny-channel blockade and inhibition of the Ca2+-related system by BAPTA, making it a useful tool for further investigation. Simulation results suggest that a detailed description of the intracellular Ca2+ fluxes is fully compatible with the observation that If is a major component of pacemaking and rate modulation. PMID:22711956

Fifty years of atomic time-keeping at VNIIFTRI

NASA Astrophysics Data System (ADS)

Domnin, Yu; Gaigerov, B.; Koshelyaevsky, N.; Poushkin, S.; Rusin, F.; Tatarenkov, V.; Yolkin, G.

2005-06-01

Time metrology in Russia in the second half of the twentieth century has been marked, as in other advanced countries, by the rapid development of time and frequency quantum standards and the beginning of atomic time-keeping. This brief review presents the main developments and studies in time and frequency measurement, and the improvement of accuracy and atomic time-keeping at the VNIIFTRI—the National Metrology Institute keeping primary time and frequency standards and ensuring unification of measurement. The milestones along the way have been the ammonia and hydrogen masers, primary caesium beam and fountain standards and laser frequency standards. For many years, VNIIFTRI was the only world laboratory that applied hydrogen-maser clock ensembles for time-keeping. VNIIFTRI's work on international laser standard frequency comparisons and absolute frequency measurements contributed greatly to the adoption by the CIPM of a highly accurate value for the He-Ne/CH4 laser frequency. VNIIFTRI and the VNIIM were the first to establish a united time, frequency and length standard.

Polarized Negative Light Ions at the Cooler Synchrotron COSY/Juelich

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gebel, R.; Felden, O.; Rossen, P. von

2005-04-06

The polarized ion source at the cooler synchrotron facility COSY of the research centre Juelich in Germany delivers negative polarized protons or deuterons for medium energy experiments. The polarized ion source, originally built by the universities of Bonn, Erlangen and Cologne, is based on the colliding beams principle, using after an upgrade procedure an intense pulsed neutralized caesium beam for charge exchange with a pulsed highly polarized hydrogen beam. The source is operated at 0.5 Hz repetition rate with 20 ms pulse length, which is the maximum useful length for the injection into the synchrotron. Routinely intensities of 20 {mu}Amore » are delivered for injection into the cyclotron of the COSY facility. For internal targets the intensity of 2 mA and a polarization up to 90% have been reached. Reliable long-term operation for experiments at COSY for up to 9 weeks has been achieved. Since 2003 polarized deuterons with different combinations of vector and tensor polarization were delivered to experiments.« less

Dynamical origin of near- and below-threshold harmonic generation of Cs in an intense mid-infrared laser field.

PubMed

Li, Peng-Cheng; Sheu, Yae-Lin; Laughlin, Cecil; Chu, Shih-I

2015-05-20

Near- and below-threshold harmonic generation provides a potential approach to generate vacuum-ultraviolet frequency comb. However, the dynamical origin of in these lower harmonics is less understood and largely unexplored. Here we perform an ab initio quantum study of the near- and below-threshold harmonic generation of caesium (Cs) atoms in an intense 3,600-nm mid-infrared laser field. Combining with a synchrosqueezing transform of the quantum time-frequency spectrum and an extended semiclassical analysis, the roles of multiphoton and multiple rescattering trajectories on the near- and below-threshold harmonic generation processes are clarified. We find that the multiphoton-dominated trajectories only involve the electrons scattered off the higher part of the combined atom-field potential followed by the absorption of many photons in near- and below-threshold regime. Furthermore, only the near-resonant below-threshold harmonic is exclusive to exhibit phase locked features. Our results shed light on the dynamic origin of the near- and below-threshold harmonic generation.

Sediment deposition rate in the Falefa River basin, Upolu Island, Samoa.

PubMed

Terry, James P; Kostaschuk, Ray A; Garimella, Sitaram

2006-01-01

The (137)Cs method was employed to investigate the recent historical rate of sediment deposition on a lowland alluvial floodplain in the Falefa River basin, Upolu Island, Samoa. Caesium stratigraphy in the floodplain sediment profile was clearly defined, with a broad peak at 145-175 cm depth. The measured rate of vertical accretion over the last 40 years is 4.0+/-0.4 cm per year. This rate exceeds observations in humid environments elsewhere, but is similar to that recorded on other tropical Pacific Islands. Available flow data for the Vaisigano River in Samoa give a 'near-catastrophic' index value of 0.6 for flood variability. This is associated with the occurrence of tropical cyclones and storms in the Samoa area. Large floods therefore probably contribute to the high rate of floodplain sedimentation on Upolu Island. A small but growing body of evidence suggests that fluvial sedimentation rates on tropical Pacific islands are some of the highest in the world.

Entangling atomic spins with a Rydberg-dressed spin-flip blockade

DOE PAGES

Jau, Y. -Y.; Hankin, A. M.; Keating, T.; ...

2015-10-05

Controlling the quantum entanglement between parts of a many-body system is key to unlocking the power of quantum technologies such as quantum computation, high-precision sensing, and the simulation of many-body physics. The spin degrees of freedom of ultracold neutral atoms in their ground electronic state provide a natural platform for such applications thanks to their long coherence times and the ability to control them with magneto-optical fields. However, the creation of strong coherent coupling between spins has been challenging. In this paper, we demonstrate a strong and tunable Rydberg-dressed interaction between spins of individually trapped caesium atoms with energy shiftsmore » of order 1 MHz in units of Planck’s constant. This interaction leads to a ground-state spin-flip blockade, whereby simultaneous hyperfine spin flips of two atoms are inhibited owing to their mutual interaction. Finally, we employ this spin-flip blockade to rapidly produce single-step Bell-state entanglement between two atoms with a fidelity ≥81(2)%.« less

Vibrational structure and antimicrobial activity of selected isonicotinates, potassium picolinate and nicotinate

NASA Astrophysics Data System (ADS)

Koczoń, P.; Piekut, J.; Borawska, M.; Lewandowski, W.

2003-06-01

The lithium, sodium, potassium, rubidium and caesium isonicotinates, potassium picolinate and nicotinate (microbiological data) as well as sodium benzoate (as a referee for microbiological tests) were under study. The selected experimental bands occurring in the FT-IR and FT-Raman spectra of studied alkaline metal isonicotinates and potassium picolinate were assigned. The change of wavenumber of those bands was observed along the metal series and along the change of position of nitrogen in the aromatic ring. The linear combination of wavenumber of assigned bands (the principal component analysis) was performed to estimate the change in the electronic properties of the molecule along the metal series. The antimicrobial activity of studied complexes against yeasts Hansenula anomala, Saccharomyces cerevisiae, and bacteria Escherichia coli and Bacillus subtilis was measured after 24 and 48 h of incubation. The attempt was made, to find out if there is any correlation between the first principal component and the degree of growth inhibition exhibited by studied complexes in relation to studied microorganisms.

Consequences of the Chernobyl fallout on some Italian underbrush produces: A ten-year study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malanca, A.; Pessina, V.; Dallara, G.

1996-11-01

In this paper we present the results of a decennial (1986-1995) investigation on radiocaesium concentrations in soil, honey, mushrooms and other underbrush produces collected in a representative upland region of the Italian Apennines. Concentrations of {sup 134}Cs and {sup 137}Cs in numerous samples were determined by gamma-ray spectrometry. The data obtained showed a relatively high {sup 137}Cs concentration, up to 8973 Bq m{sup -2}, in the superficial (0-2 cm) mineral soil. In most of the mushrooms, as well as in other underbrush produces, the detected activities were generally <20 Bq kg{sup -1}. However, a high radiocontamination was observed in twomore » species, namely Rozites Caperatus (with 584 and 735 Bq kg{sup -1} of {sup 137}Cs), and Tricholoma Nudum (3450 Bq kg{sup -1} ). Caesium concentration in honey showed a sharp increase soon after the Chernobyl accident, followed by a slow progressive decrease. 11 refs., 3 tabs.« less

Improving isotopic identification with INDRA Silicon-CsI(Tl) telescopes

NASA Astrophysics Data System (ADS)

Lopez, O.; Pârlog, M.; Borderie, B.; Rivet, M. F.; Lehaut, G.; Tabacaru, G.; Tassan-Got, L.; Pawłowski, P.; Bonnet, E.; Bougault, R.; Chbihi, A.; Dell'Aquila, D.; Frankland, J. D.; Galichet, E.; Gruyer, D.; La Commara, M.; Le Neindre, N.; Lombardo, I.; Manduci, L.; Marini, P.; Steckmeyer, J. C.; Verde, G.; Vient, E.; Wieleczko, J. P.; Indra Collaboration

2018-03-01

Profiting from previous works done with the INDRA multidetector on the description of the light response L of the CsI(Tl) crystals to different impinging nuclei, we propose an improved ΔE - L identification-calibration procedure for Silicon-Caesium Iodide (Si-CsI) telescopes, namely an Advanced Mass Estimate (AME) method. AME is compared to the usual, simple visual analysis of the corresponding two-dimensional map of ΔE - E type, by using INDRA experimental data from nuclear reactions induced by heavy ions in the Fermi energy regime. We show that the capability of such telescopes to identify both the atomic Z and the mass A numbers of light and heavy reaction products, can be quantitatively improved thanks to the proposed approach. This conclusion opens new possibilities to use INDRA for studying these reactions especially with radioactive beams. Indeed, the determination of the mass for charged reaction products becomes of paramount importance to shed light on the role of the isospin degree of freedom in the nuclear equation of state [1,2].

23.6%-efficient monolithic perovskite/silicon tandem solar cells with improved stability

NASA Astrophysics Data System (ADS)

Bush, Kevin A.; Palmstrom, Axel F.; Yu, Zhengshan J.; Boccard, Mathieu; Cheacharoen, Rongrong; Mailoa, Jonathan P.; McMeekin, David P.; Hoye, Robert L. Z.; Bailie, Colin D.; Leijtens, Tomas; Peters, Ian Marius; Minichetti, Maxmillian C.; Rolston, Nicholas; Prasanna, Rohit; Sofia, Sarah; Harwood, Duncan; Ma, Wen; Moghadam, Farhad; Snaith, Henry J.; Buonassisi, Tonio; Holman, Zachary C.; Bent, Stacey F.; McGehee, Michael D.

2017-02-01

As the record single-junction efficiencies of perovskite solar cells now rival those of copper indium gallium selenide, cadmium telluride and multicrystalline silicon, they are becoming increasingly attractive for use in tandem solar cells due to their wide, tunable bandgap and solution processability. Previously, perovskite/silicon tandems were limited by significant parasitic absorption and poor environmental stability. Here, we improve the efficiency of monolithic, two-terminal, 1-cm2 perovskite/silicon tandems to 23.6% by combining an infrared-tuned silicon heterojunction bottom cell with the recently developed caesium formamidinium lead halide perovskite. This more-stable perovskite tolerates deposition of a tin oxide buffer layer via atomic layer deposition that prevents shunts, has negligible parasitic absorption, and allows for the sputter deposition of a transparent top electrode. Furthermore, the window layer doubles as a diffusion barrier, increasing the thermal and environmental stability to enable perovskite devices that withstand a 1,000-hour damp heat test at 85 ∘C and 85% relative humidity.

Plant induced changes in concentrations of caesium, strontium and uranium in soil solution with reference to major ions and dissolved organic matter.

PubMed

Takeda, Akira; Tsukada, Hirofumi; Takaku, Yuichi; Akata, Naofumi; Hisamatsu, Shun'ichi

2008-06-01

For a better understanding of the soil-to-plant transfer of radionuclides, their behavior in the soil solution should be elucidated, especially at the interface between plant roots and soil particles, where conditions differ greatly from the bulk soil because of plant activity. This study determined the concentration of stable Cs and Sr, and U in the soil solution, under plant growing conditions. The leafy vegetable komatsuna (Brassica rapa L.) was cultivated for 26 days in pots, where the rhizosphere soil was separated from the non-rhizosphere soil by a nylon net screen. The concentrations of Cs and Sr in the rhizosphere soil solution decreased with time, and were controlled by K+NH(4)(+) and Ca, respectively. On the other hand, the concentration of U in the rhizosphere soil solution increased with time, and was related to the changes of DOC; however, this relationship was different between the rhizosphere and non-rhizosphere soil.

Investigation of the boundary layer during the transition from volume to surface dominated H- production at the BATMAN test facility

NASA Astrophysics Data System (ADS)

Wimmer, C.; Schiesko, L.; Fantz, U.

2016-02-01

BATMAN (Bavarian Test Machine for Negative ions) is a test facility equipped with a 1/8 scale H- source for the ITER heating neutral beam injection. Several diagnostics in the boundary layer close to the plasma grid (first grid of the accelerator system) followed the transition from volume to surface dominated H- production starting with a Cs-free, cleaned source and subsequent evaporation of caesium, while the source has been operated at ITER relevant pressure of 0.3 Pa: Langmuir probes are used to determine the plasma potential, optical emission spectroscopy is used to follow the caesiation process, and cavity ring-down spectroscopy allows for the measurement of the H- density. The influence on the plasma during the transition from an electron-ion plasma towards an ion-ion plasma, in which negative hydrogen ions become the dominant negatively charged particle species, is seen in a strong increase of the H- density combined with a reduction of the plasma potential. A clear correlation of the extracted current densities (jH-, je) exists with the Cs emission.

Investigation of the boundary layer during the transition from volume to surface dominated H⁻ production at the BATMAN test facility.

PubMed

Wimmer, C; Schiesko, L; Fantz, U

2016-02-01

BATMAN (Bavarian Test Machine for Negative ions) is a test facility equipped with a 18 scale H(-) source for the ITER heating neutral beam injection. Several diagnostics in the boundary layer close to the plasma grid (first grid of the accelerator system) followed the transition from volume to surface dominated H(-) production starting with a Cs-free, cleaned source and subsequent evaporation of caesium, while the source has been operated at ITER relevant pressure of 0.3 Pa: Langmuir probes are used to determine the plasma potential, optical emission spectroscopy is used to follow the caesiation process, and cavity ring-down spectroscopy allows for the measurement of the H(-) density. The influence on the plasma during the transition from an electron-ion plasma towards an ion-ion plasma, in which negative hydrogen ions become the dominant negatively charged particle species, is seen in a strong increase of the H(-) density combined with a reduction of the plasma potential. A clear correlation of the extracted current densities (j(H(-)), j(e)) exists with the Cs emission.

On-line measurement of gaseous iodine species during a PWR severe accident

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haykal, I.; Doizi, D.; Perrin, A.

A long-range remote sensing of severe accidents in nuclear power plants can be obtained by monitoring the online emission of volatile fission products such as xenon, krypton, caesium and iodine. The nuclear accident in Fukushima was ranked at level 7 of the International Nuclear Event Scale by the NISA (Nuclear and Industrial Safety Agency) according to the importance of the radionuclide release and the off-site impact. Among volatile fission products, iodine species are of high concern, since they can be released under aerosols as well as gaseous forms. Four years after the Fukushima accident, the aerosol/gaseous partition is still notmore » clear. Since the iodine gaseous forms are less efficiently trapped by the Filtered Containment Venting Systems than aerosol forms, it is of crucial importance to monitor them on-line during a nuclear accident, in order to improve the source term assessment in such a situation. Therefore, we propose to detect and quantify these iodine gaseous forms by the use of highly sensitive optical methods. (authors)« less

Time scales in the context of general relativity.

PubMed

Guinot, Bernard

2011-10-28

Towards 1967, the accuracy of caesium frequency standards reached such a level that the relativistic effect could not be ignored anymore. Corrections began to be applied for the gravitational frequency shift and for distant time comparisons. However, these corrections were not applied to an explicit theoretical framework. Only in 1991 did the International Astronomical Union provide metrics (then improved in 2000) for a definition of space-time coordinates in reference systems centred at the barycentre of the Solar System and at the centre of mass of the Earth. In these systems, the temporal coordinates (coordinate times) can be realized on the basis of one of them, the International Atomic Time (TAI), which is itself a realized time scale. The definition and the role of TAI in this context will be recalled. There remain controversies regarding the name to be given to the unit of coordinate times and to other quantities appearing in the theory. However, the idea that astrometry and celestial mechanics should adopt the usual metrological rules is progressing, together with the use of the International System of Units, among astronomers.

Stability characterization of two multi-channel GPS receivers for accurate frequency transfer.

NASA Astrophysics Data System (ADS)

Taris, F.; Uhrich, P.; Thomas, C.; Petit, G.; Jiang, Z.

In recent years, wide-spread use of the GPS common-view technique has led to major improvements, making it possible to compare remote clocks at their full level of performance. For integration times of 1 to 3 days, their frequency differences are consistently measured to about one part in 1014. Recent developments in atomic frequency standards suggest, however, that this performance may no longer be sufficient. The caesium fountain LPTF FO1, built at the BNM-LPTF, Paris, France, shows a short-term white frequency noise characterized by an Allen deviation σy(τ = 1 s) = 5×10-14 and a type B uncertainty of 2×10-15. To compare the frequencies of such highly stable standards would call for GPS common-view results to be averaged over times far exceeding the intervals of their optimal performance. Previous studies have shown the potential of carrier-phase and code measurements from geodetic GPS receivers for clock frequency comparisons. The experiment related here is an attempt to see the stability limit that could be reached using this technique.

Search for variation of fundamental constants and violations of fundamental symmetries using isotope comparisons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berengut, J. C.; Flambaum, V. V.; Kava, E. M.

2011-10-15

Atomic microwave clocks based on hyperfine transitions, such as the caesium standard, tick with a frequency that is proportional to the magnetic moment of the nucleus. This magnetic moment varies strongly between isotopes of the same atom, while all atomic electron parameters remain the same. Therefore the comparison of two microwave clocks based on different isotopes of the same atom can be used to constrain variation of fundamental constants. In this paper, we calculate the neutron and proton contributions to the nuclear magnetic moments, as well as their sensitivity to any potential quark-mass variation, in a number of isotopes ofmore » experimental interest including {sup 201,199}Hg and {sup 87,85}Rb, where experiments are underway. We also include a brief treatment of the dependence of the hyperfine transitions to variation in nuclear radius, which in turn is proportional to any change in quark mass. Our calculations of expectation values of proton and neutron spin in nuclei are also needed to interpret measurements of violations of fundamental symmetries.« less

Estimating sedimentation rates and sources in a partially urbanized catchment using caesium-137

NASA Astrophysics Data System (ADS)

Ormerod, L. M.

1998-06-01

While there has been increased interest in determining sedimentation rates and sources in agricultural and forested catchments in recent years, there have been few studies dealing with urbanized catchments. A study of sedimentation rates and sources within channel and floodplain deposits of a partially urbanized catchment has been undertaken using the 137Cs technique. Results for sedimentation rates showed no particular downstream pattern. This may be partially explained by underestimation of sedimentation rates at some sites by failure to sample the full 137Cs profile, floodplain erosion and deliberate removal of sediment. Evidence of lateral increases in net sedimentation rates with distance from the channel may be explained by increased floodplain erosion at sites closer to the channel and floodplain formation by lateral deposition. Potential sediment sources for the catchment were considered to be forest topsoil, subsurface material and sediments derived from urban areas, which were found to be predominantly subsurface material. Tracing techniques showed an increase in subsurface material for downstream sites, confirming expectations that subsurface material would increase in the downstream direction in response to the direct and indirect effects of urbanization.

Source-receptor matrix calculation with a Lagrangian particle dispersion model in backward mode

NASA Astrophysics Data System (ADS)

Seibert, P.; Frank, A.

2003-04-01

A method for the calculation of source-receptor (s-r) relationships (sensitivity of a trace substance concentration at some place and time to emission at some place and time) with Lagrangian particle models has been derived and presented previously (Air Pollution Modeling and its Application XIV, Proc. of ITM Boulder 2000). Now, the generalisation to any linear s-r relationship, including dry and wet deposition, decay etc., is presented. It was implemented in the model FLEXPART and tested extensively in idealised set-ups. These tests turned out to be very useful for finding minor model bugs and inaccuracies, and can be recommended generally for model testing. Recently, a convection scheme has been integrated in FLEXPART which was also tested. Both source and receptor can be specified in mass mixing ratio or mass units. Properly taking care of this is quite relevant for sources and receptors at different levels in the atmosphere. Furthermore, we present a test with the transport of aerosol-bound Caesium-137 from the areas contaminated by the Chernobyl disaster to Stockholm during one month.

Stable expression of hepatitis delta virus antigen in a eukaryotic cell line.

PubMed

Macnaughton, T B; Gowans, E J; Reinboth, B; Jilbert, A R; Burrell, C J

1990-06-01

The gene encoding the hepatitis delta virus structural antigen (HDAg) was linked to a neomycin resistance gene in a retrovirus expression vector, and human HepG2 cells were transfected with the recombinant plasmid. A stable cell line was cloned that expressed HDAg in the nuclei of 100% of cells, in a pattern indicating a close relationship with cell nucleoli. Analysis of partially purified recombinant HDAg by HPLC showed an Mr in the range of 7 x 10(5) to 2 x 10(6), which appeared to contain conformation-dependent epitopes, whereas the density of the antigen was 1.19 g/ml by equilibrium centrifugation in caesium chloride, and in rate zonal centrifugation it sedimented with a value of 50S, close to that of particulate hepatitis B virus surface antigen. Immunoblotting demonstrated a single polypeptide with an Mr of 24K which corresponded to the smaller of the two HDAg-specific polypeptides present in infected sera. The recombinant HDAg polypeptide was shown to be a RNA-binding protein with specificity for both genomic and antigenomic species of hepatitis delta virus RNA.

Airborne geophysical mapping as an innovative methodology for landslide investigation: evaluation of results from the Gschliefgraben landslide, Austria

NASA Astrophysics Data System (ADS)

Supper, R.; Baroň, I.; Ottowitz, D.; Motschka, K.; Gruber, S.; Winkler, E.; Jochum, B.; Römer, A.

2013-05-01

In September 2009, a complex airborne geophysical survey was performed in the large landslide affected area of the Gschliefgraben valley, Upper Austria, in order to evaluate the usability of this method for landslide detection and mapping. An evaluation of the results, including different remote sensing and ground based methods, proved that airborne geophysics, especially the airborne electromagnetic method, has a high potential for landslide investigation. This is due to its sensitivity to fluid and clay content and porosity, which are parameters showing characteristic values in landslide prone structures. Resistivity distributions in different depth levels as well as depth-slices along selected profiles are presented and compared with ground geoelectrical profiles for the test area of Gschliefgraben. Further interesting results can be derived from the radiometric survey, whereas the naturally occurring radioisotopes 40K and 232Th, as well as the man-made nuclide 137Cs have been considered. While the content of potassium and thorium in the shallow subsurface layer is expressively related to the lithological composition, the distribution of caesium is mainly determined by mass wasting processes.

Airborne geophysical mapping as an innovative methodology for landslide investigation: evaluation of results from the Gschliefgraben landslide, Austria

NASA Astrophysics Data System (ADS)

Supper, R.; Baroň, I.; Ottowitz, D.; Motschka, K.; Gruber, S.; Winkler, E.; Jochum, B.; Römer, A.

2013-12-01

In September 2009, a complex airborne geophysical survey was performed in the large landslide affected area of the Gschliefgraben valley, Upper Austria, in order to evaluate the applicability of this method for landslide detection and mapping. An evaluation of the results, including different remote-sensing and ground-based methods, proved that airborne geophysics, especially the airborne electromagnetic method, has a high potential for landslide investigation. This is due to its sensitivity to fluid and clay content and porosity, which are parameters showing characteristic values in landslide prone structures. Resistivity distributions in different depth levels as well as depth slices along selected profiles are presented and compared with ground geoelectrical profiles for the test area of Gschliefgraben. Further interesting results can be derived from the radiometric survey, whereas the naturally occurring radioisotopes 40K and 232Th, as well as the man-made nuclide 137Cs have been considered. While the content of potassium and thorium in the shallow subsurface layer is expressively related to the lithological composition, the distribution of caesium is mainly determined by mass wasting processes.

Polyoxometalate electrocatalysts based on earth-abundant metals for efficient water oxidation in acidic media

NASA Astrophysics Data System (ADS)

Blasco-Ahicart, Marta; Soriano-López, Joaquín; Carbó, Jorge J.; Poblet, Josep M.; Galan-Mascaros, J. R.

2018-01-01

Water splitting is a promising approach to the efficient and cost-effective production of renewable fuels, but water oxidation remains a bottleneck in its technological development because it largely relies on noble-metal catalysts. Although inexpensive transition-metal oxides are competitive water oxidation catalysts in alkaline media, they cannot compete with noble metals in acidic media, in which hydrogen production is easier and faster. Here, we report a water oxidation catalyst based on earth-abundant metals that performs well in acidic conditions. Specifically, we report the enhanced catalytic activity of insoluble salts of polyoxometalates with caesium or barium counter-cations for oxygen evolution. In particular, the barium salt of a cobalt-phosphotungstate polyanion outperforms the state-of-the-art IrO2 catalyst even at pH < 1, with an overpotential of 189 mV at 1 mA cm-2. In addition, we find that a carbon-paste conducting support with a hydrocarbon binder can improve the stability of metal-oxide catalysts in acidic media by providing a hydrophobic environment.

Acoustic-optical phonon up-conversion and hot-phonon bottleneck in lead-halide perovskites

PubMed Central

Yang, Jianfeng; Wen, Xiaoming; Xia, Hongze; Sheng, Rui; Ma, Qingshan; Kim, Jincheol; Tapping, Patrick; Harada, Takaaki; Kee, Tak W.; Huang, Fuzhi; Cheng, Yi-Bing; Green, Martin; Ho-Baillie, Anita; Huang, Shujuan; Shrestha, Santosh; Patterson, Robert; Conibeer, Gavin

2017-01-01

The hot-phonon bottleneck effect in lead-halide perovskites (APbX3) prolongs the cooling period of hot charge carriers, an effect that could be used in the next-generation photovoltaics devices. Using ultrafast optical characterization and first-principle calculations, four kinds of lead-halide perovskites (A=FA+/MA+/Cs+, X=I−/Br−) are compared in this study to reveal the carrier-phonon dynamics within. Here we show a stronger phonon bottleneck effect in hybrid perovskites than in their inorganic counterparts. Compared with the caesium-based system, a 10 times slower carrier-phonon relaxation rate is observed in FAPbI3. The up-conversion of low-energy phonons is proposed to be responsible for the bottleneck effect. The presence of organic cations introduces overlapping phonon branches and facilitates the up-transition of low-energy modes. The blocking of phonon propagation associated with an ultralow thermal conductivity of the material also increases the overall up-conversion efficiency. This result also suggests a new and general method for achieving long-lived hot carriers in materials. PMID:28106061

137Cs activity concentration in wild boar meat may still exceed the permitted levels

NASA Astrophysics Data System (ADS)

Rachubik, J.

2012-04-01

The radiocaesium activity concentration may still remain high in natural products such as game meat, wild mushrooms, and forest berries even more than two decades after the Chernobyl accident. The results of regular control studies of game meat conducted in Poland showed wild boars as the most contaminated game animals. It is well documented that some mushrooms, readily consumed by animals, show high ability to accumulate caesium radioisotopes. Bay bolete, one of the most wide-spread mushroom species in Poland, reveals a unique radiocaesium accumulation feature. Moreover, deer truffle, containing also particularly high levels of radiocaesium, could be another radionu-clide source for wild boars. Furthermore, animals consuming deer truffles could digest contaminated soil components. Among 94 wild boar meat samples analysed in 2008-2009, two exceeded the permitted level. Hence, some precautions should be taken in the population with an elevated intake of wild boar meat. Moreover, since each hunted wild boar is examined for the presence of Trichinella larvae, regular measurements of radiocaesium concentrations in these animals may be advisable for enhancing consumer safety.

A novel use of the caesium-137 technique to estimate human interference and historical water level in a Mediterranean Temporary Pond.

PubMed

Foteinis, Spyros; Mpizoura, Katerina; Panagopoulos, Giorgos; Chatzisymeon, Efthalia; Kallithrakas-Kontos, Nikolaos; Manutsoglu, Emmanouil

2014-01-01

The sustainability of, and the effects of human pressures on, Omalos Mediterranean Temporary Pond (MTP), Chanea, Greece was assessed. The (137)Cs technique was used to identify alleged anthropogenic interference (excavation) in the studied area. It was found that about one third of the ponds bed surface material had been removed and disposed of on the northeast edge, confirming unplanned excavations that took place in the MTP area some years ago. Nonetheless, five years after the excavation, the MTP's ecosystem (flora and fauna) had recovered, which indicates that these small ecosystems are resilient to direct human pressures, like excavations. Moreover, with the (137)Cs technique it was possible to identify the historical water level of Omalos MTP, when the fallout from the Chernobyl accident reached this area, in May of 1986. Therefore, the (137)Cs technique can be useful in the identification of the historical water level of small MTPs and other ephemeral water bodies. Applications include the verification and validation of hydrological models. Copyright © 2013 Elsevier Ltd. All rights reserved.

Changes in ambient dose equivalent rates around roads at Kawamata town after the Fukushima accident.

PubMed

Kinase, Sakae; Sato, Satoshi; Sakamoto, Ryuichi; Yamamoto, Hideaki; Saito, Kimiaki

2015-11-01

Changes in ambient dose equivalent rates noted through vehicle-borne surveys have elucidated ecological half-lives of radioactive caesium in the environment. To confirm that the ecological half-lives are appropriate for predicting ambient dose equivalent rates within living areas, it is important to ascertain ambient dose equivalent rates on/around roads. In this study, radiation monitoring on/around roads at Kawamata town, located about 37 km northwest of the Fukushima Daiichi Nuclear Power Plant, was performed using monitoring vehicles and survey meters. It was found that the ambient dose equivalent rates around roads were higher than those on roads as of October 2012. And withal the ecological half-lives on roads were essentially consistent with those around roads. With dose predictions using ecological half-lives on roads, it is necessary to make corrections to ambient dose equivalent rates through the vehicle-borne surveys against those within living areas. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Assessment of contemporary erosion/sedimentation rates trend within a small well-cultivated catchments using caesium-137 as a chronomarker (on the example of the Republic of Tatarstan, Russia)

NASA Astrophysics Data System (ADS)

Sharifullin, Aidar; Gusarov, Artem; Gafurov, Artur; Golosov, Valentin

2017-04-01

An analysis of sedimentation at a first order valley bottoms allows us to receive a sufficiently reliable quantitative evaluation of soil losses from the catchment area for two time intervals: 1963-1986 and 1987-2015 and its temporal variability. The studied catchment "Temeva River" with total area 1.13 km2 is located in the northwestern part of the Republic of Tatarstan (the Myósha river basin). Combination methods and approaches were used for evaluation of sediment redistribution for the both time intervals, including detail geodetic survey of the main morphological units of the valley, large scale geomorphological mapping, cesium-137 technique for the sediment dating in the typical locations of the valley bottom, calculation of soil losses using modified version of USLE and State Hydrological Institute models. In addition available information was collected from the local meteorological stations about some climate characteristics dynamics for the period 1950-2015. Landsat images were applied for evaluation of possible changes of land use. Crop management coefficients were calculated separately for the rainfall season and snow-melt using available data about crop-rotation dynamics for the last 55 years. In the results it was found the significant decrease of average annual soil losses from the cultivated part of the "Temeva River" catchment for the period 1987-2015 if it is compare with period 1963-1986. Such conclusion is mainly based on the different sedimentation rates in the valley bottom: for the period of 1963-1986 the average sedimentation rates were 0.92-1.81 cm per year, while the period of 1987-2015 the rates were 0.17-0.50 cm per year. The main reason for this significant decrease sediment redistribution within the catchment is the reduction of surface runoff caused by climate warming in the region. It is led to the reduction of soils freezing depth and water reserves in a snow cover before the snow-melt, and to the sharp decline in the frequency of extreme (storm) precipitation (>50 mm per a day). The influence of agricultural activity on the erosion and sedimentation changeability was insignificant, although some regional variation of crop rotation including an increase in the proportion of perennial grasses obviously caused the decline in soil losses during warm period of year. The similar trend of erosion/sedimentation rates due to mostly climate changes was identified for south-western sector of the East European Plain, but the more serious reduction of erosion rates is established for the Middle Volga region. Keywords: erosion, sedimentation, sediment, caesium-137, dry valley, small catchment, cultivated lands, Republic of Tatarstan, East European Plain.

Deuterium results at the negative ion source test facility ELISE

NASA Astrophysics Data System (ADS)

Kraus, W.; Wünderlich, D.; Fantz, U.; Heinemann, B.; Bonomo, F.; Riedl, R.

2018-05-01

The ITER neutral beam system will be equipped with large radio frequency (RF) driven negative ion sources, with a cross section of 0.9 m × 1.9 m, which have to deliver extracted D- ion beams of 57 A at 1 MeV for 1 h. On the extraction from a large ion source experiment test facility, a source of half of this size is being operational since 2013. The goal of this experiment is to demonstrate a high operational reliability and to achieve the extracted current densities and beam properties required for ITER. Technical improvements of the source design and the RF system were necessary to provide reliable operation in steady state with an RF power of up to 300 kW. While in short pulses the required D- current density has almost been reached, the performance in long pulses is determined in particular in Deuterium by inhomogeneous and unstable currents of co-extracted electrons. By application of refined caesium evaporation and distribution procedures, and reduction and symmetrization of the electron currents, considerable progress has been made and up to 190 A/m2 D-, corresponding to 66% of the value required for ITER, have been extracted for 45 min.

Antigenic characterisation of yeast-expressed lyssavirus nucleoproteins.

PubMed

Kucinskaite, Indre; Juozapaitis, Mindaugas; Serva, Andrius; Zvirbliene, Aurelija; Johnson, Nicholas; Staniulis, Juozas; Fooks, Anthony R; Müller, Thomas; Sasnauskas, Kestutis; Ulrich, Rainer G

2007-12-01

In Europe, three genotypes of the genus Lyssavirus, family Rhabdoviridae, are present, classical rabies virus (RABV, genotype 1), European bat lyssavirus type 1 (EBLV-1, genotype 5) and European bat lyssavirus type 2 (EBLV-2, genotype 6). The entire authentic nucleoprotein (N protein) encoding sequences of RABV (challenge virus standard, CVS, strain), EBLV-1 and EBLV-2 were expressed in yeast Saccharomyces cerevisiae at high level. Purification of recombinant N proteins by caesium chloride gradient centrifugation resulted in yields between 14-17, 25-29 and 18-20 mg/l of induced yeast culture for RABV-CVS, EBLV-1 and EBLV-2, respectively. The purified N proteins were evaluated by negative staining electron microscopy, which revealed the formation of nucleocapsid-like structures. The antigenic conformation of the N proteins was investigated for their reactivity with monoclonal antibodies (mAbs) directed against different lyssaviruses. The reactivity pattern of each mAb was virtually identical between immunofluorescence assay with virus-infected cells, and ELISA and dot blot assay using the corresponding recombinant N proteins. These observations lead us to conclude that yeast-expressed lyssavirus N proteins share antigenic properties with naturally expressed virus protein. These recombinant proteins have the potential for use as components of serological assays for lyssaviruses.

Development of the Long Pulse Negative Ion Source for ITER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemsworth, R.S.; Svensson, L.; Esch, H.P.L. de

2005-04-06

A model of the ion source designed for the neutral beam injectors of the International Thermonuclear Experimental Reactor (ITER), the KAMABOKO III ion source, is being tested on the MANTIS test stand at the DRFC Cadarache in collaboration with JAERI, Japan, who designed and supplied the ion source. The ion source is attached to a 3 grid 30 keV accelerator (also supplied by JAERI) and the accelerated negative ion current is determined from the energy deposited on a calorimeter located 1.6 m from the source.During experiments on MANTIS three adverse effects of long pulse operation were found: The negative ionmore » current to the calorimeter is {approx_equal}50% of that obtained from short pulse operation Increasing the plasma grid (PG) temperature results in {<=}40% enhancement in negative ion yield, substantially below that reported for short pulse operation, {>=}100%. The caesium 'consumption' is up to 1500 times that expected.Results presented here indicate that each of these is, at least partially, explained by thermal effects. Additionally presented are the results of a detailed characterisation of the source, which enable the most efficient mode of operation to be identified.« less

Synthesis of recombinant human parainfluenza virus 1 and 3 nucleocapsid proteins in yeast Saccharomyces cerevisiae.

PubMed

Juozapaitis, Mindaugas; Zvirbliene, Aurelija; Kucinskaite, Indre; Sezaite, Indre; Slibinskas, Rimantas; Coiras, Mayte; de Ory Manchon, Fernando; López-Huertas, María Rosa; Pérez-Breña, Pilar; Staniulis, Juozas; Narkeviciute, Irena; Sasnauskas, Kestutis

2008-05-01

Human parainfluenza virus types 1 and 3 (HPIV1 and HPIV3, respectively), members of the virus family Paramyxoviridae, are common causes of lower respiratory tract infections in infants, young children, the immunocompromised, the chronically ill, and the elderly. In order to synthesize recombinant HPIV1 and HPIV3 nucleocapsid proteins, the coding sequences were cloned into the yeast Saccharomyces cerevisiae expression vector pFGG3 under control of GAL7 promoter. A high level of recombinant virus nucleocapsid proteins expression (20-24 mg l(-1) of yeast culture) was obtained. Electron microscopy demonstrated the assembly of typical herring-bone structures of purified recombinant nucleocapsid proteins, characteristic for other paramyxoviruses. These structures contained host RNA, which was resistant to RNase treatment. The nucleocapsid proteins were stable in yeast and were easily purified by caesium chloride gradient ultracentrifugation. Therefore, this system proved to be simple, efficient and cost-effective, suitable for high-level production of parainfluenza virus nucleocapsids as nucleocapsid-like particles. When used as coating antigens in an indirect ELISA, the recombinant N proteins reacted with sera of patients infected with HPIV1 or 3. Serological assays to detect HPIV-specific antibodies could be designed on this basis.

Dispersal of the radionuclide caesium-137 ((137)Cs) from point sources in the Barents and Norwegian Seas and its potential contamination of the Arctic marine food chain: coupling numerical ocean models with geographical fish distribution data.

PubMed

Heldal, Hilde Elise; Vikebø, Frode; Johansen, Geir Odd

2013-09-01

Dispersal of (137)Cs from the nuclear submarine wrecks Komsomolets and K-159, which are resting on the seabed in the Norwegian and Barents Seas, respectively, is simulated using realistic rates and hypothetical scenarios. Furthermore, spatiotemporal (137)Cs concentrations in Northeast Arctic cod and capelin are estimated based on survey data. The results indicate that neither continuous leakages nor pulse discharges will cause concentrations of (137)Cs in cod muscle or whole body capelin exceeding the intervention level of 600 Bq/kg fw. Continuous leakages from Komsomolets and K-159 and pulse discharges from Komsomolets induced negligible activity concentrations in cod and capelin. A pulse discharge of 100% of the (137)Cs-inventory of K-159 will, however, result in concentrations in muscle of cod of above 100 times the present levels in the eastern Barents Sea. Within three years after the release, (137)Cs levels above 20 Bq/kg fw in cod are no longer occurring in the Barents Sea. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dispersal of the radionuclide caesium-137 (137Cs) from point sources in the Barents and Norwegian Seas and its potential contamination of the Arctic marine food chain: coupling numerical ocean models with geographical fish distribution data.

PubMed

Heldal, Hilde Elise; Vikebø, Frode; Johansen, Geir Odd

2012-05-01

Dispersal of (137)Cs from Komsomolets and K-159 is simulated using realistic rates and hypothetical scenarios. Furthermore, spatiotemporal (137)Cs concentrations in Northeast Arctic cod and capelin are estimated based on survey data. The results indicate that only pulse discharges from K-159 will cause concentrations of (137)Cs in cod muscle exceeding the intervention level of 600 Bq/kg fresh weight. A discharge of ≥10% of the (137)Cs-inventory will result in concentrations in muscle of cod exceeding the intervention level for approximately two years. In fact, a discharge of 10% of the (137)Cs-inventory results in an overlap of 8-30% between the different size groups of cod and levels that exceed the intervention level during the first year after the discharge. For capelin, individuals less than one year old during the first year after a discharge are more likely to be severely affected by discharges comprising ≥50% of the inventory. Copyright © 2012 Elsevier Ltd. All rights reserved.

Two-stage magnetic refrigerator for astronomical applications with reservoir temperatures above 4 K

NASA Astrophysics Data System (ADS)

Hagmann, C.; Richards, P. L.

We propose a novel adiabatic demagnetization refrigerator (ADR) to produce temperatures as low as 100 mK starting from a high temperature reservoir between 4 and 8 K. The high temperature reservoir for the ADR can be provided by a mechanical cooler or an unpumped liquid helium bath. This refrigerator can be used to cool bolometric infrared detectors for low background astronomy from mountain tops, balloons or satellites, as well as to cool cryogenic X-ray detectors. The two-stage ADR consists of a single magnet with a paramagnetic chromic caesium alum (CCA) salt pill to produce the low temperature and paramagnetic gadolinium gallium garnet (GGG) as the first stage to intercept heat from the high temperature reservoir. Thermal contact between the paramagnets and the reservoir during magnetization is made with a mechanical heat switch. The ADR is suspended with Kevlar cords under tension for high mechanical stiffness and low parasitic heat leak. In a single cycle, the ADR maintains a temperature of 100 mK for 10-100 h. This time depends strongly on the magnetic field and reservoir temperature but not on the volume of the paramagnetic material as long as the heat leak is dominated by the suspension.

Efficient ambient-air-stable solar cells with 2D-3D heterostructured butylammonium-caesium-formamidinium lead halide perovskites

NASA Astrophysics Data System (ADS)

Wang, Zhiping; Lin, Qianqian; Chmiel, Francis P.; Sakai, Nobuya; Herz, Laura M.; Snaith, Henry J.

2017-09-01

Perovskite solar cells are remarkably efficient; however, they are prone to degradation in water, oxygen and ultraviolet light. Cation engineering in 3D perovskite absorbers has led to reduced degradation. Alternatively, 2D Ruddlesden-Popper layered perovskites exhibit improved stability, but have not delivered efficient solar cells so far. Here, we introduce n-butylammonium cations into a mixed-cation lead mixed-halide FA0.83Cs0.17Pb(IyBr1-y)3 3D perovskite. We observe the formation of 2D perovskite platelets, interspersed between highly orientated 3D perovskite grains, which suppress non-radiative charge recombination. We investigate the relationship between thin-film composition, crystal alignment and device performance. Solar cells with an optimal butylammonium content exhibit average stabilized power conversion efficiency of 17.5 ± 1.3% with a 1.61-eV-bandgap perovskite and 15.8 ± 0.8% with a 1.72-eV-bandgap perovskite. The stability under simulated sunlight is also enhanced. Cells sustain 80% of their 'post burn-in' efficiency after 1,000 h in air, and close to 4,000 h when encapsulated.

The metrology of time.

PubMed

Arias, Elisa Felicitas

2005-09-15

Measuring time is a continuous activity, an international and restless enterprise hidden in time laboratories spread all over the planet. The Bureau International des Poids et Mesures is charged with coordinating activities for international timekeeping and it makes use of the world's capacity to produce a remarkably stable and accurate reference time-scale. Commercial atomic clocks beating the second in national laboratories can reach a stability of one part in 10(14) over a 5 day averaging time, compelling us to research the most highly performing methods of remote clock comparison. The unit of the international time-scale is the second of the International System of Units, realized with an uncertainty of the order 10(-15) by caesium fountains. Physicists in a few time laboratories are making efforts to gain one order of magnitude in the uncertainty of the realization of the second, and more refined techniques of time and frequency transfer are in development to accompany this progress. Femtosecond comb technology will most probably contribute in the near future to enhance the definition of the second with the incorporation of optical clocks. We will explain the evolution of the measuring of time, current state-of-the-art measures and future challenges.

The chemical state of defective uranium-plutonium oxide fuel pins irradiated in sodium cooled reactors

NASA Astrophysics Data System (ADS)

Kleykamp, H.

1997-09-01

Steady-state irradiation experiments were conducted in the sodium loop of the Siloe reactor on artificially failed mixed oxide pins that had been pre-irradiated in fast reactors up to 11.5% burnup. The formation of the predominant reaction product Na 3(U,Pu)O 4 starts on the fuel surface and is terminated when a lower O/(U + Pu) threshold of the fuel is attained. The axial extent of the reaction product depends on the size of the initial cladding defect. The occurrence of secondary cracks is possible. Na(U,Pu)O 3 forms at higher fuel temperatures. The existence of Na 3U 1- xPu xO 4 is shown in pre-irradiated blanket pins after artificial defect formation. Caesium in the oxocompounds is reduced to the metallic state and is dissolved in the coolant. Evidence of a very low chemical potential of oxygen in defective fuel pins is sustained by the occurrence of actinide-platinum metal phases formed by coupled reduction of hypostoichiometric fuel with ɛ-(Mo,Tc,Ru,Rh,Pd) precipitates. Continued operation of defective pins is not hazardous by easy precautions.

A versatile dual-species Zeeman slower for caesium and ytterbium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, S. A., E-mail: s.a.hopkins@durham.ac.uk; Butler, K.; Guttridge, A.

2016-04-15

We describe the design, construction, and operation of a versatile dual-species Zeeman slower for both Cs and Yb, which is easily adaptable for use with other alkali metals and alkaline earths. With the aid of analytic models and numerical simulation of decelerator action, we highlight several real-world problems affecting the performance of a slower and discuss effective solutions. To capture Yb into a magneto-optical trap (MOT), we use the broad {sup 1}S{sub 0} to {sup 1}P{sub 1} transition at 399 nm for the slower and the narrow {sup 1}S{sub 0} to {sup 3}P{sub 1} intercombination line at 556 nm formore » the MOT. The Cs MOT and slower both use the D2 line (6{sup 2}S{sub 1/2} to 6{sup 2}P{sub 3/2}) at 852 nm. The slower can be switched between loading Yb or Cs in under 0.1 s. We demonstrate that within a few seconds the Zeeman slower loads more than 10{sup 9} Yb atoms and 10{sup 8} Cs atoms into their respective MOTs. These are ideal starting numbers for further experiments on ultracold mixtures and molecules.« less

Alkali and alkaline earth metal salts of tetrazolone: structurally interesting and excellently thermostable.

PubMed

He, Piao; Wu, Le; Wu, Jin-Ting; Yin, Xin; Gozin, Michael; Zhang, Jian-Guo

2017-07-04

Tetrazolone (5-oxotetrazole) was synthesized by a moderate strategy through three steps (addition, cyclization and catalytic hydrogenation) avoiding the unstable intermediate diazonium, as reported during the previous preparation. Alkali and alkaline earth metal salts with lithium (1), sodium (2), potassium (3), rubidium (4) caesium (5), magnesium (6), calcium (7), strontium (8) and barium (9) were prepared and fully characterized using elemental analysis, IR and NMR spectroscopy, DSC and TG analysis. All metal salts were characterized via single-crystal X-ray diffraction. They crystallize in common space groups with high densities ranging from 1.479 (1) to 3.060 g cm -3 (5). Furthermore, the crystal structures of 7, 8 and 9 reveal interesting porous energetic coordination polymers with strong hydrogen bond interactions. All new salts have good thermal stabilities with decomposition temperature between 215.0 °C (4) and 328.2 °C (7), significantly higher than that of the reported nitrogen-rich salt neutral tetrazolone. The sensitivities towards impact and friction were tested using standard methods, and all the tetrazolone-based compounds investigated can be classified into insensitive. The flame test of these metal salts supports their potential use as perchlorate-free pyrotechnics or eco-friendly insensitive energetic materials.

Adapting the Caesium-137 technique to document soil redistribution rates associated with traditional cultivation practices in Haiti.

PubMed

Velasco, H; Astorga, R Torres; Joseph, D; Antoine, J S; Mabit, L; Toloza, A; Dercon, G; Walling, Des E

2018-03-01

Large-scale deforestation, intensive land use and unfavourable rainfall conditions are responsible for significant continuous degradation of the Haitian uplands. To develop soil conservation strategies, simple and cost-effective methods are needed to assess rates of soil loss from farmland in Haiti. The fallout radionuclide caesium-137 ( 137 Cs) provides one such means of documenting medium-term soil redistribution rates. In this contribution, the authors report the first use in Haiti of 137 Cs measurements to document soil redistribution rates and the associated pattern of erosion/sedimentation rates along typical hillslopes within a traditional upland Haitian farming area. The local 137 Cs reference inventory, measured at an adjacent undisturbed flat area, was 670 Bq m -2 (SD = 100 Bq m -2 , CV = 15%, n = 7). Within the study area, where cultivation commenced in 1992 after deforestation, three representative downslope transects were sampled. These were characterized by 137 Cs inventories ranging from 190 to 2200 Bq m -2 . Although, the study area was cultivated by the local farmers, the 137 Cs depth distributions obtained from the area differed markedly from those expected from a cultivated area. They showed little evidence of tillage mixing within the upper part of the soil or, more particularly, of the near-uniform activities normally associated with the plough layer or cultivation horizon. They were very similar to that found at the reference site and were characterized by high 137 Cs activities at the surface and much lower activities at greater depths. This situation is thought to reflect the traditional manual tillage practices which cause limited disturbance and mixing of the upper part of the soil. It precluded the use of the conversion models normally used to estimate soil redistribution rates from 137 Cs measurements on cultivated soils and the Diffusion and Migration conversion model frequently used for uncultivated soils was modified for application to the cultivated soils of the study area, in order to take account of the unusual local conditions. The model was also modified to take account of the fact that cultivation in the study area commenced in 1992, rather than predating the period of weapons test fallout which extended from the mid 1950s to the 1970s. Erosion rates on the upper parts of the hillside involved in the study were found to be relatively high and ca. -23 t ha -1 y -1 with low spatial variability. In the lower, flatter areas at the bottom of the slope, deposition occurred. Deposition rates were characterized by high spatial variability, ranging from 6.0 to 71 t ha -1 y -1 . Soil redistribution rates of this magnitude are a cause for concern and there is an urgent need to implement soil conservation measures to ensure the longer-term sustainability of the local agricultural practices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ionic mechanism of a two-component cholinergic inhibition in Aplysia neurones

PubMed Central

Kehoe, Jacsue

1972-01-01

1. A two-component inhibition, consisting of a rapid and slow i.p.s.p., has been observed in the medial cells of the pleural ganglion of Aplysia. Each i.p.s.p. has been shown to be mediated by a distinct cholinergic receptor. The ionic mechanisms of the two components of the inhibitory response (whether elicited synaptically or by ACh injection) are analysed in this paper. 2. The inversion potential (typically -60 mV) of the rapid i.p.s.p. and of the rapid response to ACh injection is selectively altered by an intracellular injection of chloride or by partial substitution of the external chloride by impermeant anions. The shift caused by this last procedure is similar to that predicted for the chloride equilibrium potential (ECl) by the Nernst equation. 3. The slow i.p.s.p. and the slow response to ACh injection (both of which invert around -80 mV) are insensitive to changes in either internal or external chloride concentrations; on the contrary, with alterations of the concentration of potassium in the external medium, the inversion potential of the slow responses is altered in a way similar to that expected for the potassium equilibrium potential (EK). 4. It is concluded that the rapid i.p.s.p. and the corresponding ACh potential are due to a change in chloride permeability of the post-synaptic membrane, whereas the slow responses are due to a selective change in potassium permeability. 5. Additional data suggest that the fast, `chloride' channel is impermeable to sulphate and methylsulphate, but slightly permeable to propionate and isethionate. The slow, `potassium' channel is impermeable to caesium ions, whereas its permeability to rubidium ions is half that to potassium. 6. The potassium permeability of both the non-synaptic and synaptic membrane is markedly reduced by an intracellular injection of either tetraethylammonium (TEA) or caesium. These ions not only block the cholinergic potassium currents (whether inward or outward) but likewise block the potassium currents activated in the same cells by an iontophoretic injection of dopamine. 7. The potassium dependent synaptic potentials are also selectively affected by manipulations known to block the electrogenic sodium pump. In the presence of ouabain or in sea water in which sodium has been replaced by lithium, there is an apparent reduction of these potentials which was shown to be simply a reflexion of the movement of EK towards a less polarized level. This shift in inversion potential was not seen for the potassium dependent response to ACh iontophoretic injection. These results are interpreted in terms of accumulation of potassium ions assumed to occur in the extracellular spaces of the neuropile, but not in the thoroughly dissected somatic region. 8. Cooling was shown to eliminate, selectively, the synaptic and ACh potential changes caused by an increase in potassium permeability. PMID:4679686

Monte Carlo calculated doses to treatment volumes and organs at risk for permanent implant lung brachytherapy

NASA Astrophysics Data System (ADS)

Sutherland, J. G. H.; Furutani, K. M.; Thomson, R. M.

2013-10-01

Iodine-125 (125I) and Caesium-131 (131Cs) brachytherapy have been used with sublobar resection to treat stage I non-small cell lung cancer and other radionuclides, 169Yb and 103Pd, are considered for these treatments. This work investigates the dosimetry of permanent implant lung brachytherapy for a range of source energies and various implant sites in the lung. Monte Carlo calculated doses are calculated in a patient CT-derived computational phantom using the EGsnrc user-code BrachyDose. Calculations are performed for 103Pd, 125I, 131Cs seeds and 50 and 100 keV point sources for 17 implant positions. Doses to treatment volumes, ipsilateral lung, aorta, and heart are determined and compared to those determined using the TG-43 approach. Considerable variation with source energy and differences between model-based and TG-43 doses are found for both treatment volumes and organs. Doses to the heart and aorta generally increase with increasing source energy. TG-43 underestimates the dose to the heart and aorta for all implants except those nearest to these organs where the dose is overestimated. Results suggest that model-based dose calculations are crucial for selecting prescription doses, comparing clinical endpoints, and studying radiobiological effects for permanent implant lung brachytherapy.

Engaging with local stakeholders: some lessons from Fukushima for recovery.

PubMed

Hayano, R S

2015-06-01

The Fukushima Daiichi nuclear power plant accident contaminated the soil of densely populated regions in Fukushima prefecture with radioactive caesium, which poses significant risks of internal and external exposure to the residents. Applying the knowledge of post-Chernobyl accident studies, internal exposures in excess of a few mSv per year would be expected to be common in Fukushima. However, extensive whole-body-counter surveys have shown that the internal exposure levels of residents are much lower than estimated; in 2012-2013, the Cs-137 detection percentages (the detection limit being ∼300 Bq body(-1)) were approximately 1% for adults and practically 0% for children. These results are consistent with those of many other measurements/studies conducted to date in Fukushima. As a consequence, risks from external exposure assume greater importance for the majority of residents in Fukushima due to the lower contribution from internal exposure. In both cases, average doses remain low, although some residents are exposed to higher-than-average risks; it is these members of the population who need to be identified and followed-up. Consequently, it is essential to re-establish communication at all levels in society. © The International Society for Prosthetics and Orthotics Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

π-electron S = ½ quantum spin-liquid state in an ionic polyaromatic hydrocarbon

NASA Astrophysics Data System (ADS)

Takabayashi, Yasuhiro; Menelaou, Melita; Tamura, Hiroyuki; Takemori, Nayuta; Koretsune, Takashi; Štefančič, Aleš; Klupp, Gyöngyi; Buurma, A. Johan C.; Nomura, Yusuke; Arita, Ryotaro; Arčon, Denis; Rosseinsky, Matthew J.; Prassides, Kosmas

2017-07-01

Molecular solids with cooperative electronic properties based purely on π electrons from carbon atoms offer a fertile ground in the search for exotic states of matter, including unconventional superconductivity and quantum magnetism. The field was ignited by reports of high-temperature superconductivity in materials obtained by the reaction of alkali metals with polyaromatic hydrocarbons, such as phenanthrene and picene, but the composition and structure of any compound in this family remained unknown. Here we isolate the binary caesium salts of phenanthrene, Cs(C14H10) and Cs2(C14H10), to show that they are multiorbital strongly correlated Mott insulators. Whereas Cs2(C14H10) is diamagnetic because of orbital polarization, Cs(C14H10) is a Heisenberg antiferromagnet with a gapped spin-liquid state that emerges from the coupled highly frustrated Δ-chain magnetic topology of the alternating-exchange spiral tubes of S = ½ (C14H10)•- radical anions. The absence of long-range magnetic order down to 1.8 K (T/J ≈ 0.02 J is the dominant exchange constant) renders the compound an excellent candidate for a spin-½ quantum-spin liquid (QSL) that arises purely from carbon π electrons.

Comparative visualization of digital mammograms on clinical 2K monitor workstations and hardcopy: a contrast detail analysis

NASA Astrophysics Data System (ADS)

Torbica, Pavle; Buchberger, Wolfgang; Bernathova, M.; Mallouhi, Ammar; Peer, Siegfried; Bosmans, Hilde; Faulkner, Keith

2003-05-01

The purpose of this study was to compare the radiologist`s performance in detecting small low-contrast objects with hardcopy and softcopy reading of digital mammograms. 12 images of a contrast-detail (CD) phantom without and with 25.4 mm, 50.8 mm, and 76.2 mm additional polymethylmetacrylate (PMMA) attenuation were acquired with a caesium iodid/amorphous silicon flat panel detector under standard exposure conditions. The phantom images were read by three independent observers, by conducting a four-alternative forced-choice experiment. Reading of the hardcopy was done on a mammography viewbox under standardized reading conditions. For soft copy reading, a dedicated workstation with two 2K monitors was used. CD-curves and image quality figure (IQF) values were calculated from the correct detection rates of randomly located gold disks in the phantom. The figures were compared for both reading conditions and for different PMMA layers. For all types of exposures, soft copy reading resulted in significantly better contrast-detail characteristics and IQF values, as compared to hard copy reading of laser printouts. (p< 0.01). The authors conclude that the threshold contrast characteristics of digital mammograms displayed on high-resolution monitors are sufficient to make soft copy reading of digital mammograms feasible.

Evaluating laser-driven Bremsstrahlung radiation sources for imaging and analysis of nuclear waste packages.

PubMed

Jones, Christopher P; Brenner, Ceri M; Stitt, Camilla A; Armstrong, Chris; Rusby, Dean R; Mirfayzi, Seyed R; Wilson, Lucy A; Alejo, Aarón; Ahmed, Hamad; Allott, Ric; Butler, Nicholas M H; Clarke, Robert J; Haddock, David; Hernandez-Gomez, Cristina; Higginson, Adam; Murphy, Christopher; Notley, Margaret; Paraskevoulakos, Charilaos; Jowsey, John; McKenna, Paul; Neely, David; Kar, Satya; Scott, Thomas B

2016-11-15

A small scale sample nuclear waste package, consisting of a 28mm diameter uranium penny encased in grout, was imaged by absorption contrast radiography using a single pulse exposure from an X-ray source driven by a high-power laser. The Vulcan laser was used to deliver a focused pulse of photons to a tantalum foil, in order to generate a bright burst of highly penetrating X-rays (with energy >500keV), with a source size of <0.5mm. BAS-TR and BAS-SR image plates were used for image capture, alongside a newly developed Thalium doped Caesium Iodide scintillator-based detector coupled to CCD chips. The uranium penny was clearly resolved to sub-mm accuracy over a 30cm(2) scan area from a single shot acquisition. In addition, neutron generation was demonstrated in situ with the X-ray beam, with a single shot, thus demonstrating the potential for multi-modal criticality testing of waste materials. This feasibility study successfully demonstrated non-destructive radiography of encapsulated, high density, nuclear material. With recent developments of high-power laser systems, to 10Hz operation, a laser-driven multi-modal beamline for waste monitoring applications is envisioned. Copyright © 2016. Published by Elsevier B.V.

A neutron track etch detector for electron linear accelerators in radiotherapy

PubMed Central

Vukovic, Branko; Faj, Dario; Poje, Marina; Varga, Maja; Radolic, Vanja; Miklavcic, Igor; Ivkovic, Ana; Planinic, Josip

2010-01-01

Background Electron linear accelerators in medical radiotherapy have replaced cobalt and caesium sources of radiation. However, medical accelerators with photon energies over 10 MeV generate undesired fast neutron contamination in a therapeutic X-ray photon beam. Photons with energies above 10 MeV can interact with the atomic nucleus of a high-Z material, of which the target and the head of an accelerator consist, and lead to the neutron ejection. Results and conclusions. Our neutron dosimeter, composed of the LR-115 track etch detector and boron foil BN-1 converter, was calibrated on thermal neutrons generated in the nuclear reactor of the Josef Stefan Institute (Slovenia), and applied to dosimetry of undesirable neutrons in photon radiotherapy by the linear accelerator 15 MV Siemens Mevatron. Having considered a high dependence of a cross-section between neutron and boron on neutron energy, and broad neutron spectrum in a photon beam, as well as outside the entrance door to maze of the Mevatron, we developed a method for determining the effective neutron detector response. A neutron dose rate in the photon beam was measured to be 1.96 Sv/h. Outside the Mevatron room the neutron dose rate was 0.62 μSv/h. PACS: 87.52. Ga; 87.53.St; 29.40.Wk. PMID:22933893

Mechanistic approach for nitride fuel evolution and fission product release under irradiation

NASA Astrophysics Data System (ADS)

Dolgodvorov, A. P.; Ozrin, V. D.

2017-01-01

A model for describing uranium-plutonium mixed nitride fuel pellet burning was developed. Except fission products generating, the model includes impurities of oxygen and carbon. Nitrogen behaviour in nitride fuel was analysed and the nitrogen chemical potential in solid solution with uranium-plutonium nitride was constructed. The chemical program module was tested with the help of thermodynamic equilibrium phase distribution calculation. Results were compared with analogous data in literature, quite good agreement was achieved, especially for uranium sesquinitride, metallic species and some oxides. Calculation of a process of nitride fuel burning was also conducted. Used mechanistic approaches for fission product evolution give the opportunity to find fission gas release fractions and also volumes of intergranular secondary phases. Calculations present that the most massive secondary phases are the oxide and metallic phases. Oxide phase contain approximately 1 % wt of substance over all time of burning with slightly increasing of content. Metallic phase has considerable rising of mass and by the last stage of burning it contains about 0.6 % wt of substance. Intermetallic phase has less increasing rate than metallic phase and include from 0.1 to 0.2 % wt over all time of burning. The highest element fractions of released gaseous fission products correspond to caesium and iodide.

Negative hydrogen ions in a linear helicon plasma device

NASA Astrophysics Data System (ADS)

Corr, Cormac; Santoso, Jesse; Samuell, Cameron; Willett, Hannah; Manoharan, Rounak; O'Byrne, Sean

2015-09-01

Low-pressure negative ion sources are of crucial importance to the development of high-energy (>1 MeV) neutral beam injection systems for the ITER experimental tokamak device. Due to their high power coupling efficiency and high plasma densities, helicon devices may be able to reduce power requirements and potentially remove the need for caesium. In helicon sources, the RF power can be coupled efficiently into the plasma and it has been previously observed that the application of a small magnetic field can lead to a significant increase in the plasma density. In this work, we investigate negative ion dynamics in a high-power (20 kW) helicon plasma source. The negative ion fraction is measured by probe-based laser photodetachment, electron density and temperature are determined by a Langmuir probe and tuneable diode laser absorption spectroscopy is used to determine the density of the H(n = 2) excited atomic state and the gas temperature. The negative ion density and excited atomic hydrogen density display a maximum at a low applied magnetic field of 3 mT, while the electron temperature displays a minimum. The negative ion density can be increased by a factor of 8 with the application of the magnetic field. Spatial and temporal measurements will also be presented. The Australian Research Grants Council is acknowledged for funding.

The ITER Neutral Beam Test Facility towards SPIDER operation

NASA Astrophysics Data System (ADS)

Toigo, V.; Dal Bello, S.; Gaio, E.; Luchetta, A.; Pasqualotto, R.; Zaccaria, P.; Bigi, M.; Chitarin, G.; Marcuzzi, D.; Pomaro, N.; Serianni, G.; Agostinetti, P.; Agostini, M.; Antoni, V.; Aprile, D.; Baltador, C.; Barbisan, M.; Battistella, M.; Boldrin, M.; Brombin, M.; Dalla Palma, M.; De Lorenzi, A.; Delogu, R.; De Muri, M.; Fellin, F.; Ferro, A.; Gambetta, G.; Grando, L.; Jain, P.; Maistrello, A.; Manduchi, G.; Marconato, N.; Pavei, M.; Peruzzo, S.; Pilan, N.; Pimazzoni, A.; Piovan, R.; Recchia, M.; Rizzolo, A.; Sartori, E.; Siragusa, M.; Spada, E.; Spagnolo, S.; Spolaore, M.; Taliercio, C.; Valente, M.; Veltri, P.; Zamengo, A.; Zaniol, B.; Zanotto, L.; Zaupa, M.; Boilson, D.; Graceffa, J.; Svensson, L.; Schunke, B.; Decamps, H.; Urbani, M.; Kushwah, M.; Chareyre, J.; Singh, M.; Bonicelli, T.; Agarici, G.; Garbuglia, A.; Masiello, A.; Paolucci, F.; Simon, M.; Bailly-Maitre, L.; Bragulat, E.; Gomez, G.; Gutierrez, D.; Mico, G.; Moreno, J.-F.; Pilard, V.; Chakraborty, A.; Baruah, U.; Rotti, C.; Patel, H.; Nagaraju, M. V.; Singh, N. P.; Patel, A.; Dhola, H.; Raval, B.; Fantz, U.; Fröschle, M.; Heinemann, B.; Kraus, W.; Nocentini, R.; Riedl, R.; Schiesko, L.; Wimmer, C.; Wünderlich, D.; Cavenago, M.; Croci, G.; Gorini, G.; Rebai, M.; Muraro, A.; Tardocchi, M.; Hemsworth, R.

2017-08-01

SPIDER is one of two projects of the ITER Neutral Beam Test Facility under construction in Padova, Italy, at the Consorzio RFX premises. It will have a 100 keV beam source with a full-size prototype of the radiofrequency ion source for the ITER neutral beam injector (NBI) and also, similar to the ITER diagnostic neutral beam, it is designed to operate with a pulse length of up to 3600 s, featuring an ITER-like magnetic filter field configuration (for high extraction of negative ions) and caesium oven (for high production of negative ions) layout as well as a wide set of diagnostics. These features will allow a reproduction of the ion source operation in ITER, which cannot be done in any other existing test facility. SPIDER realization is well advanced and the first operation is expected at the beginning of 2018, with the mission of achieving the ITER heating and diagnostic NBI ion source requirements and of improving its performance in terms of reliability and availability. This paper mainly focuses on the preparation of the first SPIDER operations—integration and testing of SPIDER components, completion and implementation of diagnostics and control and formulation of operation and research plan, based on a staged strategy.

The aftermath of the Fukushima nuclear accident: Measures to contain groundwater contamination.

PubMed

Gallardo, Adrian H; Marui, Atsunao

2016-03-15

Several measures are being implemented to control groundwater contamination at the Fukushima Daiichi Nuclear Plant. This paper presents an overview of work undertaken to contain the spread of radionuclides, and to mitigate releases to the ocean via hydrological pathways. As a first response, contaminated water is being held in tanks while awaiting treatment. Limited storage capacity and the risk of leakage make the measure unsustainable in the long term. Thus, an impervious barrier has been combined with a drain system to minimize the discharge of groundwater offshore. Caesium in seawater at the plant port has largely dropped, although some elevated concentrations are occasionally recorded. Moreover, a dissimilar decline of the radioactivity in fish could indicate additional sources of radionuclides intake. An underground frozen shield is also being constructed around the reactors. This structure would reduce inflows to the reactors and limit the interaction between fresh and contaminated waters. Additional strategies include groundwater abstraction and paving of surfaces to lower water levels and further restrict the mobilisation of radionuclides. Technical difficulties and public distrust pose an unprecedented challenge to the site remediation. Nevertheless, the knowledge acquired during the initial work offers opportunities for better planning and more rigorous decisions in the future. Copyright © 2016 Elsevier B.V. All rights reserved.

First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant

PubMed Central

Tomono, Dai; Mizumoto, Tetsuya; Takada, Atsushi; Komura, Shotaro; Matsuoka, Yoshihiro; Mizumura, Yoshitaka; Oda, Makoto; Tanimori, Toru

2017-01-01

We have developed an Electron Tracking Compton Camera (ETCC), which provides a well-defined Point Spread Function (PSF) by reconstructing a direction of each gamma as a point and realizes simultaneous measurement of brightness and spectrum of MeV gamma-rays for the first time. Here, we present the results of our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in Japan in 2014. The obtained distribution of brightness (or emissivity) with remote-sensing observations is unambiguously converted into the dose distribution. We confirm that the dose distribution is consistent with the one taken by conventional mapping measurements with a dosimeter physically placed at each grid point. Furthermore, its imaging spectroscopy, boosted by Compton-edge-free spectra, reveals complex radioactive features in a quantitative manner around each individual target point in the background-dominated environment. Notably, we successfully identify a “micro hot spot” of residual caesium contamination even in an already decontaminated area. These results show that the ETCC performs exactly as the geometrical optics predicts, demonstrates its versatility in the field radiation measurement, and reveals potentials for application in many fields, including the nuclear industry, medical field, and astronomy. PMID:28155883

Caesium-137 and strontium-90 temporal series in the Tagus River: experimental results and a modelling study.

PubMed

Miró, Conrado; Baeza, Antonio; Madruga, María J; Periañez, Raul

2012-11-01

The objective of this work consisted of analysing the spatial and temporal evolution of two radionuclide concentrations in the Tagus River. Time-series analysis techniques and numerical modelling have been used in this study. (137)Cs and (90)Sr concentrations have been measured from 1994 to 1999 at several sampling points in Spain and Portugal. These radionuclides have been introduced into the river by the liquid releases from several nuclear power plants in Spain, as well as from global fallout. Time-series analysis techniques have allowed the determination of radionuclide transit times along the river, and have also pointed out the existence of temporal cycles of radionuclide concentrations at some sampling points, which are attributed to water management in the reservoirs placed along the Tagus River. A stochastic dispersion model, in which transport with water, radioactive decay and water-sediment interactions are solved through Monte Carlo methods, has been developed. Model results are, in general, in reasonable agreement with measurements. The model has finally been applied to the calculation of mean ages of radioactive content in water and sediments in each reservoir. This kind of model can be a very useful tool to support the decision-making process after an eventual emergency situation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Natural and anthropogenic radionuclide activity concentrations in the New Zealand diet.

PubMed

Pearson, Andrew J; Gaw, Sally; Hermanspahn, Nikolaus; Glover, Chris N

2016-01-01

To support New Zealand's food safety monitoring regime, a survey was undertaken to establish radionuclide activity concentrations across the New Zealand diet. This survey was undertaken to better understand the radioactivity content of the modern diet and also to assess the suitability of the current use of milk as a sentinel for dietary radionuclide trends. Thirteen radionuclides were analysed in 40 common food commodities, including animal products, fruits, vegetables, cereal grains and seafood. Activity was detected for (137)Caesium, (90)Strontium and (131)Iodine. No other anthropogenic radionuclides were detected. Activity concentrations of the three natural radionuclides of Uranium and the daughter radionuclide (210)Polonium were detected in the majority of food sampled, with a large variation in magnitude. The maximum activity concentrations were detected in shellfish for all these radionuclides. Based on the established activity concentrations and ranges, the New Zealand diet contains activity concentrations of anthropogenic radionuclides far below the Codex Alimentarius guideline levels. Activity concentrations obtained for milk support its continued use as a sentinel for monitoring fallout radionuclides in terrestrial agriculture. The significant levels of natural and anthropogenic radionuclide activity concentrations detected in finfish and molluscs support undertaking further research to identify a suitable sentinel for New Zealand seafood monitoring. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Interfacial engineering of electron transport layer using Caesium Iodide for efficient and stable organic solar cells

NASA Astrophysics Data System (ADS)

Upama, Mushfika Baishakhi; Elumalai, Naveen Kumar; Mahmud, Md Arafat; Wright, Matthew; Wang, Dian; Xu, Cheng; Haque, Faiazul; Chan, Kah Howe; Uddin, Ashraf

2017-09-01

Polymer solar cells (PSCs) have gained immense research interest in the recent years predominantly due to low-cost, solution process-ability, and facile device fabrication. However, achieving high stability without compromising the power conversion efficiency (PCE) serves to be an important trade-off for commercialization. In line with this, we demonstrate the significance of incorporating a CsI/ZnO bilayer as electron transport layer (ETL) in the bulk heterojunction PSCs employing low band gap polymer (PTB7) and fullerene (PC71BM) as the photo-active layer. The devices with CsI/ZnO interlayer exhibited substantial enhancement of 800% and 12% in PCE when compared to the devices with pristine CsI and pristine ZnO as ETL, respectively. Furthermore, the UV and UV-ozone induced degradation studies revealed that the devices incorporating CsI/ZnO bilayer possess excellent decomposition stability (∼23% higher) over the devices with pristine ZnO counterparts. The incorporation of CsI between ITO and ZnO was found to favorably modify the energy-level alignment at the interface, contributing to the charge collection efficiency as well as protecting the adjacent light absorbing polymer layers from degradation. The mechanism behind the improvement in PCE and stability is analyzed using the electrochemical impedance spectroscopy and dark I-V characteristics.

Aqueous alkali halide solutions: can osmotic coefficients be explained on the basis of the ionic sizes alone?

PubMed

Kalyuzhnyi, Yu V; Vlachy, Vojko; Dill, Ken A

2010-06-21

We use the AMSA, associative mean spherical theory of associative fluids, to study ion-ion interactions in explicit water. We model water molecules as hard spheres with four off-center square-well sites and ions as charged hard spheres with sticky sites that bind to water molecules or other ions. We consider alkali halide salts. The choice of model parameters is based on two premises: (i) The strength of the interaction between a monovalent ion and a water molecule is inversely proportional to the ionic (crystal) diameter sigma(i). Smaller ions bind to water more strongly than larger ions do, taking into account the asymmetry of the cation-water and anion-water interactions. (ii) The number of contacts an ion can make is proportional to sigma2(i). In short, small ions bind waters strongly, but only a few of them. Large ions bind waters weakly, but many of them. When both a monovalent cation and anion are large, it yields a small osmotic coefficient of the salt, since the water molecules avoid the space in between large ions. On the other hand, salts formed from one small and one large ion remain hydrated and their osmotic coefficient is high. The osmotic coefficients, calculated using this model in combination with the integral equation theory developed for associative fluids, follow the experimental trends, including the unusual behavior of caesium salts.

Organic integrated circuits for information storage based on ambipolar polymers and charge injection engineering

NASA Astrophysics Data System (ADS)

Dell'Erba, Giorgio; Luzio, Alessandro; Natali, Dario; Kim, Juhwan; Khim, Dongyoon; Kim, Dong-Yu; Noh, Yong-Young; Caironi, Mario

2014-04-01

Ambipolar semiconducting polymers, characterized by both high electron (μe) and hole (μh) mobility, offer the advantage of realizing complex complementary electronic circuits with a single semiconducting layer, deposited by simple coating techniques. However, to achieve complementarity, one of the two conduction paths in transistors has to be suppressed, resulting in unipolar devices. Here, we adopt charge injection engineering through a specific interlayer in order to tune injection into frontier energy orbitals of a high mobility donor-acceptor co-polymer. Starting from field-effect transistors with Au contacts, showing a p-type unbalanced behaviour with μh = 0.29 cm2/V s and μe = 0.001 cm2/V s, through the insertion of a caesium salt interlayer with optimized thickness, we obtain an n-type unbalanced transistor with μe = 0.12 cm2/V s and μh = 8 × 10-4 cm2/V s. We applied this result to the development of the basic pass-transistor logic building blocks such as inverters, with high gain and good noise margin, and transmission-gates. In addition, we developed and characterized information storage circuits like D-Latches and D-Flip-Flops consisting of 16 transistors, demonstrating both their static and dynamic performances and thus the suitability of this technology for more complex circuits such as display addressing logic.

Development and validation of an automated unit for the extraction of radiocaesium from seawater.

PubMed

Bokor, Ilonka; Sdraulig, Sandra; Jenkinson, Peter; Madamperuma, Janaka; Martin, Paul

2016-01-01

An automated unit was developed for the in-situ extraction of radiocaesium ((137)Cs and (134)Cs) from large volumes of seawater to achieve very low detection limits. The unit was designed for monitoring of Australian ocean and coastal waters, including at ports visited by nuclear-powered warships. The unit is housed within a robust case, and is easily transported and operated. It contains four filter cartridges connected in series. The first two cartridges are used to remove any suspended material that may be present in the seawater, while the last two cartridges are coated with potassium copper hexacyanoferrate for caesium extraction. Once the extraction is completed the coated cartridges are ashed. The ash is transferred to a small petri dish for counting of (137)Cs and (134)Cs by high resolution gamma spectrometry for a minimum of 24 h. The extraction method was validated for the following criteria: selectivity, trueness, precision, linearity, limit of detection and traceability. The validation showed the unit to be fit for purpose with the method capable of achieving low detection limits required for environmental samples. The results for the environmental measurements in Australian seawater correlate well with those reported in the Worldwide Marine Radioactivity Study (WOMARS). The cost of preparation and running the system is low and waste generation is minimal. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

ACES microwave link requirements.

PubMed

Uhrich, P M; Guillernot, P; Aubry, P; Gonzalez, F; Salomon, C

2000-01-01

Atomic Clock Ensemble in Space (ACES) is a project of the European Space Agency on-board the future International Space Station (ISS). The payload consists mainly of two atomic frequency standards, one space hydrogen maser (SHM) prepared by the Observatoire de Neuchatel (Switzerland), and one cold atom caesium clock called PHARAO prepared by the CNES (France), with the participation of the BNM-LPTF, the ENS-LKB, and the CNRS-LHA. Because of the anticipated performances of these clocks on-board the ISS, the requirements of the links between the payload and the clocks on the Earth are at the limits of the known potential of the optical or microwave techniques. The microwave link (MWL) requirements are described in this paper. Taking into account the characteristics of the ISS orbit, and fixing an arbitrary limit to the additional noise brought to the clock readings by the MWL, the computation of the required stability leads to two kinds of requirements: the first one at the subpicosecond level over each single continuous pass of the ISS above any Earth station, and the second one at the level of one part in 10(16) and below over a one day or more averaging period. Moreover, the ISS orbit parameters should lead to a knowledge of the ACES clock position at the m level, and of the ACES clock speed at the mm/s level.

Precise Receiver Clock Offset Estimations According to Each Global Navigation Satellite Systems (GNSS) Timescales

NASA Astrophysics Data System (ADS)

Thongtan, Thayathip; Tirawanichakul, Pawit; Satirapod, Chalermchon

2017-12-01

Each GNSS constellation operates its own system times; namely, GPS system time (GPST), GLONASS system time (GLONASST), BeiDou system time (BDT) and Galileo system time (GST). They could be traced back to Coordinated Universal Time (UTC) scale and are aligned to GPST. This paper estimates the receiver clock offsets to three timescales: GPST, GLONASST and BDT. The two measurement scenarios use two identical multi-GNSS geodetic receivers connected to the same geodetic antenna through a splitter. One receiver is driven by its internal oscillators and another receiver is connected to the external frequency oscillators, caesium frequency standard, kept as the Thailand standard time scale at the National Institute of Metrology (Thailand) called UTC(NIMT). The three weeks data are observed at 30 seconds sample rate. The receiver clock offsets with respected to the three system time are estimated and analysed through the geodetic technique of static Precise Point Positioning (PPP) using a data processing software developed by Wuhan University - Positioning And Navigation Data Analyst (PANDA) software. The estimated receiver clock offsets are around 32, 33 and 18 nanoseconds from GPST, GLONASST and BDT respectively. This experiment is initially stated that each timescale is inter-operated with GPST and further measurements on receiver internal delay has to be determined for clock comparisons especially the high accuracy clock at timing laboratories.

THE USE OF HELICOPTERS FOR EMERGENCY DISTRICT SURVEY AFTER AN ACCIDENTAL RELEASE OF RADIOACTIVE MATERIAL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lister, B.A.J.

1963-10-31

The possible use of helicopters in carrying out rapid district gamma radiation surveys was studied using standard portabie equipment operated by regular health physics operations staff. Measurements have been made of radiation levels at various heights up to 1000 feet above point sources of iodine- 131 and caesium-137 and above arrays of iodine-131 sources. The results show than an area contaminated to a level of 0.4 c iodine-131/m/sup 2/ (corresponding to the imposition of emergency restrictions on milk consumption) can be readily detected using a scintillation ratemeter at a height of 50-100 ft. This sensitivity is similar to that whichmore » can be obtained using a fixed wing aircraft at 500 ft employing more elaborate techniques. The type of helicopter used is available as a continuous emergency service operated by the Royal Air Force. Operational flying tests have indicated the main problems whlch would be met during an emergency survey, and the advantages to be gained from the use of helicopters either in close support of a carborne survey or in areas where a carborne survey is impracticable. A suitable technique for such an aerial survey has been worked out and an agreement for assistance now exists between A.E.R.E. Harwell and R.A.F. Coastal Command. (auth)« less

Spectral response characteristics of the transmission-mode aluminum gallium nitride photocathode with varying aluminum composition.

PubMed

Hao, Guanghui; Liu, Junle; Ke, Senlin

2017-12-10

In order to research spectral response characteristics of transmission-mode nanostructure aluminum gallium nitride (AlGaN) photocathodes, the AlGaN photocathodes materials with varied aluminum (Al) composition were grown by metalorganic chemical vapor deposition (MOCVD) and its optical properties were measured. The Al compositions of each AlGaN film of the photocathodes were analyzed from their adsorption properties curves; their thickness was also calculated by the matrix formula of thin-film optics. The nanostructure AlGaN photocathodes were activated with the Caesium-Oxygen (Cs-O) alternation, and after the photocathode was packaged in vacuum, their spectrum responses were measured. The experimental results showed that the trend of spectrum response curves first increased and then decreased along with the increasing of the incident light wavelength. The peak spectrum response value was 17.5 mA/W at 255 nm, and its quantum efficiency was 8.5%. The lattice defects near the interface of the AlGaN heterostructure could impede the electron motion crossing this region and moving toward the photocathode surface; this was a factor that reduces the electron emission performance of the photocathodes. Also, the experimental result showed that the thickness of each AlGaN layer affected the electron diffusion characteristics; this was a key factor that influenced the spectrum response performance.

137Caesium in samples of wild-grown Boletus edulis Bull. from Lucca province (Tuscany, Italy) and other Italian and European geographical areas.

PubMed

Betti, Laura; Palego, Lionella; Lucacchini, Antonio; Giannaccini, Gino

2017-01-01

Samples of the edible mushroom Boletus edulis Bull. were studied to assess the risk for human health related to their content of the artificial radionuclide 137 Cs. Fresh B. edulis carpophores were collected in four undeveloped microhabitats of Lucca province (Tuscany, North-Central Italy). Dried non-cultivated samples coming from this same district and 11 other Italian provinces or European countries were instead purchased fromcommercial sources. Contents of 137 Cs, reported as Bq kg ‒1 dry weight (dw), were measured by γ-spectrometry. The radionuclide concentration varied depending on the gathering site in fresh samples, with 41.8 ± 5.2 Bq kg ‒1 dw at site 1 (Tosco-Emiliani Apennine) and four-fold less, 12.8 ± 1.3 Bq kg ‒1 dw, at site 2 (Apuan Alps). Moreover, fresh or dried carpophores from Lucca province displayed among the lowest 137 Cs contents in Europe. Average 137 Cs levels in all analysed samples were substantially below the legal threshold for edible mushrooms, 600 Bq kg ‒1 dw. Conclusively, we report that 137 Cs amounts in B. edulis depend on both the distance from the Chernobyl accident and multifactorial features of collection sites. We also show that the consumption of European B. edulis does not represent a major health risk with respect to 137 Cs radio contamination.

Vertical migration of plutonium-239 + -240, americium-241 and caesium-137 fallout in a forest soil under spruce.

PubMed

Bunzl, K; Kracke, W; Schimmack, W

1992-03-01

The vertical activity distributions of fallout 238Pu, 239+240Pu, 241Am, 134Cs and 137Cs in a forest soil (Hapludult) were determined at several locations in a spruce stand separately according to their origin (global fallout or Chernobyl fallout). To determine the rate of migration of these radionuclides in each soil horizon, the observed depth profiles of the radionuclides were evaluated with a compartment model. In the top organic horizons (LOf1 and Of2), the migration rates for all radionuclides from both sources were above 0.5 cm per year. In the Oh horizon the migration rates observed for global fallout Pu, Am and Cs were similar (0.2-0.4 cm per year). Compared with Pu, however, the mobility of Am is slightly, but statistically significantly, enhanced. The highest rate in this layer was found for Chernobyl-derived radiocaesium (2 cm per year). In the layers of the mineral horizon (depth 0-2, 2-5 and 5-10 cm) the observed migration rates were very similar for global fallout Pu (0.08-0.7 cm per year) and Am (0.1-2 cm per year). In comparison, the migration rate of global fallout radiocaesium was about half in each layer. The highest rate was observed again for Chernobyl-derived radiocaesium (0.5-3 cm per year).

Quantum teleportation between light and matter.

PubMed

Sherson, Jacob F; Krauter, Hanna; Olsson, Rasmus K; Julsgaard, Brian; Hammerer, Klemens; Cirac, Ignacio; Polzik, Eugene S

2006-10-05

Quantum teleportation is an important ingredient in distributed quantum networks, and can also serve as an elementary operation in quantum computers. Teleportation was first demonstrated as a transfer of a quantum state of light onto another light beam; later developments used optical relays and demonstrated entanglement swapping for continuous variables. The teleportation of a quantum state between two single material particles (trapped ions) has now also been achieved. Here we demonstrate teleportation between objects of a different nature--light and matter, which respectively represent 'flying' and 'stationary' media. A quantum state encoded in a light pulse is teleported onto a macroscopic object (an atomic ensemble containing 10 caesium atoms). Deterministic teleportation is achieved for sets of coherent states with mean photon number (n) up to a few hundred. The fidelities are 0.58 +/- 0.02 for n = 20 and 0.60 +/- 0.02 for n = 5--higher than any classical state transfer can possibly achieve. Besides being of fundamental interest, teleportation using a macroscopic atomic ensemble is relevant for the practical implementation of a quantum repeater. An important factor for the implementation of quantum networks is the teleportation distance between transmitter and receiver; this is 0.5 metres in the present experiment. As our experiment uses propagating light to achieve the entanglement of light and atoms required for teleportation, the present approach should be scalable to longer distances.

Efficient removal of caesium ions from aqueous solution using a calix crown ether in ionic liquids: mechanism and radiation effect.

PubMed

Xu, Chao; Yuan, Liyong; Shen, Xinghai; Zhai, Maolin

2010-04-28

The removal of radioactive (137)Cs from nuclear waste is of great importance for both the environment and energy saving. Herein, we report a study on the removal of Cs(+) using a calix crown ether bis(2-propyloxy)calix[4]crown-6 (BPC6) in ionic liquids [C(n)mim][NTf(2)], where [C(n)mim](+) is 1-alkyl-3-methylimidazolium and [NTf(2)](-) is bis(trifluoromethylsulfonyl)imide. The BPC6/[C(n)mim][NTf(2)] system is highly efficient in removing Cs(+) from aqueous solution, even at a low concentration of BPC6. HNO(3) and metal ions such as Na(+), Al(3+) in the aqueous phase interfered with the extraction of Cs(+) by competitive interaction with BPC6 and/or salting-out effect. UV analysis confirmed that the extraction of Cs(+) by the BPC6/[C(n)mim][NTf(2)] system involves a dual extraction mechanism, i.e., via exchange of BPC6.Cs(+) complex or Cs(+) by [C(n)mim](+). Irradiation of [C(4)mim][NTf(2)] dramatically decreases Cs(+) partitioning in the ionic liquid phase by the competitive interaction of radiation-generated H(+) with BPC6, while irradiation of BPC6/[C(4)mim][NTf(2)] decreases Cs(+) partitioning more markedly due to the radiolysis of BPC6.

Studies on Human Hepatitis A Virus in Chimpanzees

PubMed Central

Thornton, A.; Tsiquaye, K. N.; Zuckerman, A. J.

1977-01-01

Several chimpanzees found to be seronegative for hepatitis A by immune electron microscopy and by radioimmunoassay were inoculated with known infective faecal extracts from several sources, including the MS-1 strain of hepatitis A virus, first passage material from chimpanzee George and a strain of hepatitis A virus obtained during a naturally occurring outbreak of infection in Germany. Elevated serum transaminase levels were found in the chimpanzees about 19 days after inoculation. Virus particles were found in faeces as early as 9 days after infection in one chimpanzee and by days 12 and 14 in the others. Excretion of virus continued for 9 to 19 days, and the maximum numbers of virus particles were found on the 17th to the 19th day after inoculation. The buoyant density in caesium chloride of virus particles separated from faeces was 1.31 to 1.43 g/ml. Most of the particles were found in the fraction with a density of 1.34 g/ml. Hepatitis A antibody was detected in the serum by immune electron microscopy and by radioimmunoassay during the period of incubation while virus particles were still being excreted in the faeces and coinciding approximately with the onset of biochemical evidence of liver damage. A very close or identical morphological and serological relationship was demonstrated between hepatitis A virus isolated from man and from the experimentally infected chimpanzees. ImagesFigs. 1-3 PMID:199227

Nicotinic acetylcholine receptors in porcine hypophyseal intermediate lobe cells.

PubMed Central

Zhang, Z W; Feltz, P

1990-01-01

1. Acetylcholine (ACh) was found to depolarize isolated porcine intermediate lobe cells maintained in primary cells culture. We investigated the ACh-induced responses in both whole-cell and cell-attached configurations of the patch-clamp technique. 2. From noise analysis of ACh-evoked whole-cell currents, we estimated an elementary conductance of 20 pS and a channel open duration of about 1.7 ms at -60 mV. From single-channel recordings, we obtained a slope conductance of 26 pS and a mean open time of 1.8 ms at membrane potentials between -60 and -80 mV. 3. ACh-evoked responses were blocked by d-tubocurarine (d-TC), hexamethonium and mecamylamine, but were insensitive to alpha-bungarotoxin. These characteristics define a neuronal type of nicotinic receptors. 4. The whole-cell current induced by ACh showed a strong inward rectification with no outward current being obtained. This phenomenon was observed when the intracellular ion is either sodium or caesium, and even when Ca2+ and Mg2+ were totally removed from the intracellular medium. 5. ACh-gated channels in intermediate lobe cells were cation selective and were permeable to Na+ and Cs+. In Ca2(+)-free extracellular solution, single-channel conductances were much larger (46 pS) than in the presence of 2 mM-Ca2+ (26 pS). 6. The possibility of an excitatory cholinergic control of intermediate lobe cells is discussed. PMID:1693685

Performance of the High Momentum Particle IDentification detector of ALICE during the LHC run period 2015-2016

NASA Astrophysics Data System (ADS)

de Cataldo, G.; ALICE Collaboration

2017-12-01

In the period June 2015-September 2016 the LHC has delivered pp and Pb-Pb collisions respectively at √s=13 TeV and √sNN=5.02 TeV for a total integrated luminosity in ALICE of 14 pb-1. The High Momentum Particle IDentification detector (HMPID) is part of the ALICE experiment. It is based on seven Ring Imaging Cherenkov (RICH) modules, 1.3×1.3 m2 each, with a proximity focusing geometry. The Cherenkov photon detection is achieved by pad segmented photocathodes, coated with 300 nm thick Caesium Iodide layer, installed in multiwire proportional chambers. Liquid C6F14 (perfluorohexane) with n=1.2989 at λ=175 nm is used as Cherenkov radiator. The HMPID identifies with three sigma separation charged π and K in the momentum range 1-3 GeV/c and protons in the range 1.5-5 GeV/c. The scatter plots of the Cherenkov angle for both pp and Pb-Pb events are presented as preliminary Particle Identification (PID) performance. After the good results shown during 2010-2013, in this paper the HMPID performance in the period 2015-2016, with emphasis on the CsI quantum efficiency stability, are presented. Finally the perspectives of the detector operation in the period HL-LHC 2019-2022, are briefly discussed.

Integration of magnetometric, gpr and geoelectric measurements applied to the study of the new Viggiano archaeological site (Southern Italy).

NASA Astrophysics Data System (ADS)

Rizzo, E.; Chianese, D.; Lapenna, V.; Piscitelli, S.

2003-04-01

In the frame of a collaboration with the Archaeological Superintendence of the Basilicata Region (Southern Italy), the Geophysical Lab of IMAA-CNR planned a multidisciplinary investigation in the archaeological site of Viggiano, integrating magnetic mapping, Ground Penetrating Radar profiling and 3D electrical resistivity imaging. The archaeological site, located in Agri Valley (Southern Italy, Basilicata), is an ancient structure developed in successive phases between IV and III century B.C. In this area during some shovel tests archaeological remnants have been identified in the western part. Successively the archaeologists hypothesized the presence of buried structures in the eastern part too, where we performed a geophysical survey. In particular, a magnetic map by means of a caesium vapour magnetometer G-858 GEOMETRICS has been carried to find the external perimeter; more than 50 Georadar profiles using SIR 2000 instrument have been performed to delineate the internal buried structures and the electrical resistivity method has been applied to estimate the depth of buried structures. According to the archaeological hypothesis significant wall structures have been identified in the eastern part. In conclusion, the integration of different geophysical techniques allows us to obtain very intriguing information about the shape, the dimension and the depth of the oriental buried wall structures giving a contribute to better develop a new hypothesis about the history of the archaeological site of Viggiano.

Effect of organic complexing agents on the interactions of Cs(+), Sr(2+) and UO(2)(2+) with silica and natural sand.

PubMed

Reinoso-Maset, Estela; Worsfold, Paul J; Keith-Roach, Miranda J

2013-05-01

Sorption processes play a key role in controlling radionuclide migration through subsurface environments and can be affected by the presence of anthropogenic organic complexing agents found at contaminated sites. The effect of these complexing agents on radionuclide-solid phase interactions is not well known. Therefore the aim of this study was to examine the processes by which EDTA, NTA and picolinate affect the sorption kinetics and equilibria of Cs(+), Sr(2+) and UO2(2+) onto natural sand. The caesium sorption rate and equilibrium were unaffected by the complexing agents. Strontium however showed greater interaction with EDTA and NTA in the presence of desorbed matrix cations than geochemical modelling predicted, with SrNTA(-) enhancing sorption and SrEDTA(2-) showing lower sorption than Sr(2+). Complexing agents reduced UO2(2+) sorption to silica and enhanced the sorption rate in the natural sand system. Elevated concentrations of picolinate reduced the sorption of Sr(2+) and increased the sorption rate of UO2(2+), demonstrating the potential importance of this complexing agent. These experiments provide a direct comparison of the sorption behaviour of Cs(+), Sr(2+) and UO2(2+)onto natural sand and an assessment of the relative effects of EDTA, NTA and picolinate on the selected elements. Copyright © 2013 Elsevier Ltd. All rights reserved.

Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

NASA Astrophysics Data System (ADS)

Stohl, A.; Seibert, P.; Wotawa, G.; Arnold, D.; Burkhart, J. F.; Eckhardt, S.; Tapia, C.; Vargas, A.; Yasunari, T. J.

2011-10-01

On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP) developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4-20.0) EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started very early, possibly immediately after the earthquake and the emergency shutdown on 11 March at 06:00 UTC. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3-50.1) PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude exactly when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions were not only coming from the damaged reactor cores, but also from the spent-fuel pool of unit 4 and confirms that the spraying was an effective countermeasure. We also explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. The plume was also dispersed quickly over the entire Northern Hemisphere, first reaching North America on 15 March and Europe on 22 March. In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement with each other. Altogether, we estimate that 6.4 TBq of 137Cs, or 19% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 TBq, or 2% of the total fallout were deposited on land areas other than Japan.

EDITORIAL: Award for Patrick Gill

NASA Astrophysics Data System (ADS)

Hauptmann, Peter

2007-12-01

On behalf of the journal I would like to congratulate Professor Patrick Gill, a long-serving member of the Editorial Board for Measurement Science and Technology, who has been awarded the prestigious Institute of Physics Young medal and prize for world-leading contributions to optical frequency metrology. He is recognized as the UK leader in the quest for very accurate optical clocks. Professor Gill's work is concerned with the development of cold trapped ion systems as optical frequency standards with potential for future redefinition of the SI second, and the frequency metrology needed to relate optical and microwave standards to high accuracy. Interested readers may wish to read a short review of the wider state-of-the-art development of single cold trapped ion frequency standards, coupled with a more detailed account of results achieved at the National Physical Laboratory, written by Professor Gill and co-workers from NPL: ''Trapped ion optical frequency standards'' by P Gill, G P Barwood, H A Klein, G Huang, S A Webster, P J Blythe, K Hosaka, S N Lea and H S Margolis 2003 Meas. Sci. Technol. 14 (8) 1174-86 He was one of the very early developers of the frequency comb idea, and in 2004 he led an experiment where the femtosecond laser frequency comb measured the prototype optical clock frequency, based on a strontium-ion optical transition, with accuracy close to the capability of the best caesium microwave clocks. Once again I congratulate Professor Gill and wish him every success for his future work.

Coupled calculation of the radiological release and the thermal-hydraulic behavior of a 3-loop PWR after a SGTR by means of the code RELAP5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Hove, W.; Van Laeken, K.; Bartsoen, L.

1995-09-01

To enable a more realistic and accurate calculation of the radiological consequences of a SGTR, a fission product transport model was developed. As the radiological releases strongly depend on the thermal-hydraulic transient, the model was included in the RELAP5 input decks of the Belgian NPPs. This enables the coupled calculation of the thermal-hydraulic transient and the radiological release. The fission product transport model tracks the concentration of the fission products in the primary circuit, in each of the SGs as well as in the condenser. This leads to a system of 6 coupled, first order ordinary differential equations with timemore » dependent coefficients. Flashing, scrubbing, atomisation and dry out of the break flow are accounted for. Coupling with the thermal-hydraulic calculation and correct modelling of the break position enables an accurate calculation of the mixture level above the break. Pre- and post-accident spiking in the primary circuit are introduced. The transport times in the FW-system and the SG blowdown system are also taken into account, as is the decontaminating effect of the primary make-up system and of the SG blowdown system. Physical input parameters such as the partition coefficients, half life times and spiking coefficients are explicitly introduced so that the same model can be used for iodine, caesium and noble gases.« less

Thirty years after Chernobyl: Long-term determination of 137Cs effective half-life in the lichen Stereocaulon vesuvianum.

PubMed

Savino, F; Pugliese, M; Quarto, M; Adamo, P; Loffredo, F; De Cicco, F; Roca, V

2017-06-01

It has been widely shown that nuclear fallout includes substances, which accumulate in organisms such as crustaceans, fish, mushrooms and lichens, helping to evaluate the activity concentration of contaminants accumulated on a long time. In this context, radiocaesium deposited in soil following the Chernobyl accident on 26 April 1986 is known to have remained persistently available for plant uptake in many areas of Europe. Studies on the lichen Stereocaulon vesuvianum show the plant's high capacity to retain radionuclides from the substrate and the air. After the Chernobyl accident, starting from September 1986, at the Radioactivity Laboratory (LaRa) of the University of Naples Federico II, four monitoring campaigns to evaluate the activity concentration of four isotopes of the two elements caesium and ruthenium ( 134 Cs, 137 Cs, 103 Ru and 106 Ru) were carried out until 1999. This study allowed the effective half-life of 134 Cs and 137 Cs to be estimated. Twenty-eight years after the accident, in December 2014, a further sampling was carried out; only 137 Cs was revealed beyond the detection limits, measuring activity concentrations ranging from 20 to 40 Bq/kg, while the other radionuclides were no longer observed due to their shorter half-life. The last sampling allowed more precise determination of the effective half-life of 137 Cs (6.2 ± 0.1 year), due to the larger dataset on a large time period. Copyright © 2017 Elsevier Ltd. All rights reserved.

Preliminary estimating the contemporary sedimentation trend in dry valley bottoms of first-order catchments of different landscape zones of the Russian Plain using the 137Cs as a chronomarker

NASA Astrophysics Data System (ADS)

Sharifullin, A.; Gusarov, A.; Gafurov, A.; Essuman-Quainoo, B.

2018-01-01

A general trend of erosion processes over the last 50-60 years can be estimated by dating sediments washed off from arable lands and accumulated in the first-order dry valleys bottoms. Three small (first-order) catchments were chosen as objects of the study. They are located, respectively, in the southern part of the taiga zone, the zone of temperate broad-leaf forests and the forest-steppe zone of the Russian Plain. To date the sediments accumulated in the bottoms the radioactive caesium-137 (137Cs) of global (since 1954) and Chernobyl origin (1986) had been used as a chronomarker. The average (for all the catchments) sedimentation rates during the global 137Cs fallout period (1963(1954)-1986) are at least 0.88-2.71 cm per year.For the period that has passed since the Chernobyl accident (1986-2015(2016)) the average rates were 0.15-1.07 cm per year. The greatest reduction in the sedimentation rates is observed in the subzone of the southern taiga, the lowest one is in the forest-steppe zone of the Russian Plain. The main reason for such significant reduction in the rates of sedimentation of the soil erosion products in the dry valley bottoms was a reduction of surface runoff within the catchments during a snowmelt period, as well as crop-rotation changes there.

Radioactive caesium (134Cs and 137Cs) in mushrooms of the genus Boletus from the Reggio Emilia in Italy and Pomerania in Poland.

PubMed

Cocchi, Luigi; Kluza, Karolina; Zalewska, Tamara; Apanel, Anna; Falandysz, Jerzy

2017-12-01

Activity concentrations of 134 Cs and 137 Cs were determined in mushrooms of the Boletus species B. aereus, B. reticulatus, B. appendiculatus, B. calopus, B. edulis, B. erythropus, B. fechtneri, B. pinophilus, B. pseudoregius, B. rhodopurpureus, B. rhodoxanthus collected in the Reggio Emilia, Italy, in 1993 and 1994 and in B. edulis collected in Pomerania in northern Poland in the period from 1995-2015. Boletus edulis from the Reggio Emilia showed presence of 137 Cs at 330 ± 220 Bq kg -1 dry biomass in 1993 and at 370 ± 180 Bq kg -1 dry biomass in 1994. In B. edulis sampled in the Reggio Emilia in 1993 and 1994, the pre-Chernobyl 137 Cs from global fallout amounted to 39-46 % of the total activity concentrations of isotope 137 Cs. B. edulis from Pomerania contained 137 Cs in caps at 270 ± 15 Bq kg -1 dry biomass in 1995, and in whole fruiting bodies it was found to be 470 ± 9 Bq kg -1 dry biomass in 2015. The activity concentrations of 137 Cs determined in fruiting bodies of B. edulis from Pomerania fluctuated but persisted over the period from 1995 to 2015, while the maximum activity concentrations were well below the tolerance limit of 600 Bq kg -1 fresh product.

A dual pathways transfer model to account for changes in the radioactive caesium level in demersal and pelagic fish after the Fukushima Daï-ichi nuclear power plant accident

PubMed Central

Bailly-du-Bois, Pascal; Laguionie, Philippe; Morillon, Mehdi; Arnaud, Mireille; Cunin, Pascal

2017-01-01

The Fukushima Daï-ichi nuclear power plant (FDNPP) accident resulted in radioactive Cs being discharged into the local marine environment. While Cs bioaccumulates in biota and slowly depurates, the Cs concentrated in biota constitutes a source of Cs for animals feeding on each other. The marine biota therefore serves as a pool that recycles Cs, and this recycling process delays depuration in the fish feeding on this biota pool. Because the continental shelf is squeezed between the coast and very deep sea, the demersal marine species are confined to a narrow strip along the coast, close to the source of the radioactive input. Unlike demersal species, however, pelagic species are not restricted to the most contaminated area but instead spend some, if not most, of their time and feeding off-shore, far from the input source. We suggest that the feeding pathway for fish is a box whose size depends on their mobility, and that this feeding box is much larger and less contaminated (because of dilution through distance) for pelagic fish than for demersal fish. The aim of this paper is to test this hypothesis and to propose a simple operational model implementing two transfer routes: from seawater and from feeding. The model is then used to match the observational data in the aftermath of the FDNPP accident. PMID:28248982

Estimation of the Lyman-α signal of the EFILE diagnostic under static or radiofrequency electric field in vacuum

NASA Astrophysics Data System (ADS)

Carlo, POGGI; Théo, GUILLAUME; Fabrice, DOVEIL; Laurence, CHÉRIGIER-KOVACIC

2018-07-01

The electric field induced Lyman-α emission diagnostic aims to provide a non intrusive and precise measurement of the electric field in plasma, using a beam of hydrogen atoms prepared in the metastable 2s state. The metastable particles are obtained by means of a proton beam extracted from a hydrogen plasma source, and neutralised by interaction with vaporised caesium. When a 2s atom enters a region where an electric field is present, it undergoes a transition to the 2p state (Stark mixing). It then quickly decays to the ground level, emitting Lyman-α radiation, which is collected by a photomultiplier. The 2s\\to 2p transition rate is proportional to the square of the magnitude of the electric field, and depends on the field oscillation frequency (with peaks around 1 GHz). By measuring the intensity of the Lyman-α radiation emitted by the beam it is possible to determine the magnitude of the field in a defined region. In this work, an analysis of the behaviour of the diagnostic under static or radiofrequency electric field is presented. Electric field simulations obtained with a finite element solver of Maxwell equations, combined with theoretical calculations of the Stark mixing transition rate, are used to develop a model for the interpretation of photomultiplier data. This method shows good agreement with experimental results for the static field case, and allows to measure the field magnitude for the oscillating case.

Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies

NASA Astrophysics Data System (ADS)

Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

2011-05-01

The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.

A first characterization of the NIO1 particle beam by means of a diagnostic calorimeter

NASA Astrophysics Data System (ADS)

Pimazzoni, A.; Cavenago, M.; Cervaro, V.; Fasolo, D.; Serianni, G.; Tollin, M.; Veltri, P.

2017-08-01

Powerful neutral beam injectors (NBI) are required as heating and current drive systems for tokamaks like ITER. The development of negative ion sources and accelerators (40 A; 1 MeV D- beam) in particular, is a crucial point and many issues still require a better understanding. In this framework, the experiment NIO1 (9 beamlets of 15 mA H- each, 60 kV) operated at Consorzio RFX started operation in 2014[1]. Both its RF negative ion source (up to 2.5 kW) and its beamline are equipped with many diagnostics [2]. For the early tests on the extraction system, oxygen has been used as well as hydrogen due to its higher electronegativity, which allows reaching currents large enough to test the beam diagnostics even without caesium injection. In particular a 1D-CFC (carbon-fibre-carbon composite) tile is used as a calorimeter to determine the beam power deposition by observing the rear surface of the tile with an infra-red camera; the same design is applied as for STRIKE [3], one of the diagnostics of SPIDER (the ITER-like ion source prototype [4]) whose facility is currently under construction at Consorzio RFX. From this diagnostic it is also possible to assess the beam divergence and thus the beam optics. The present contribution describes the characterization of the NIO1 particle beam by means of temperature and current measurements with different source and accelerator parameters.

Charge injection engineering of ambipolar field-effect transistors for high-performance organic complementary circuits.

PubMed

Baeg, Kang-Jun; Kim, Juhwan; Khim, Dongyoon; Caironi, Mario; Kim, Dong-Yu; You, In-Kyu; Quinn, Jordan R; Facchetti, Antonio; Noh, Yong-Young

2011-08-01

Ambipolar π-conjugated polymers may provide inexpensive large-area manufacturing of complementary integrated circuits (CICs) without requiring micro-patterning of the individual p- and n-channel semiconductors. However, current-generation ambipolar semiconductor-based CICs suffer from higher static power consumption, low operation frequencies, and degraded noise margins compared to complementary logics based on unipolar p- and n-channel organic field-effect transistors (OFETs). Here, we demonstrate a simple methodology to control charge injection and transport in ambipolar OFETs via engineering of the electrical contacts. Solution-processed caesium (Cs) salts, as electron-injection and hole-blocking layers at the interface between semiconductors and charge injection electrodes, significantly decrease the gold (Au) work function (∼4.1 eV) compared to that of a pristine Au electrode (∼4.7 eV). By controlling the electrode surface chemistry, excellent p-channel (hole mobility ∼0.1-0.6 cm(2)/(Vs)) and n-channel (electron mobility ∼0.1-0.3 cm(2)/(Vs)) OFET characteristics with the same semiconductor are demonstrated. Most importantly, in these OFETs the counterpart charge carrier currents are highly suppressed for depletion mode operation (I(off) < 70 nA when I(on) > 0.1-0.2 mA). Thus, high-performance, truly complementary inverters (high gain >50 and high noise margin >75% of ideal value) and ring oscillators (oscillation frequency ∼12 kHz) based on a solution-processed ambipolar polymer are demonstrated.

Experimental identification of a comb-shaped chaotic region in multiple parameter spaces simulated by the Hindmarsh—Rose neuron model

NASA Astrophysics Data System (ADS)

Jia, Bing

2014-03-01

A comb-shaped chaotic region has been simulated in multiple two-dimensional parameter spaces using the Hindmarsh—Rose (HR) neuron model in many recent studies, which can interpret almost all of the previously simulated bifurcation processes with chaos in neural firing patterns. In the present paper, a comb-shaped chaotic region in a two-dimensional parameter space was reproduced, which presented different processes of period-adding bifurcations with chaos with changing one parameter and fixed the other parameter at different levels. In the biological experiments, different period-adding bifurcation scenarios with chaos by decreasing the extra-cellular calcium concentration were observed from some neural pacemakers at different levels of extra-cellular 4-aminopyridine concentration and from other pacemakers at different levels of extra-cellular caesium concentration. By using the nonlinear time series analysis method, the deterministic dynamics of the experimental chaotic firings were investigated. The period-adding bifurcations with chaos observed in the experiments resembled those simulated in the comb-shaped chaotic region using the HR model. The experimental results show that period-adding bifurcations with chaos are preserved in different two-dimensional parameter spaces, which provides evidence of the existence of the comb-shaped chaotic region and a demonstration of the simulation results in different two-dimensional parameter spaces in the HR neuron model. The results also present relationships between different firing patterns in two-dimensional parameter spaces.

Electromagnetic energy and food processing.

PubMed

Mudgett, R

1988-01-01

The use of electromagnetic energy in food processing is reviewed with respect to food safety, nutritional quality, and organoleptic quality. The effects of nonionizing radiation sources such as microwave and radio-frequency energy and ionizing radiation sources, e.g. radioactive cobalt-60 and caesium-137, on the inactivation of microbes and nutrients are compared with those of conventional heating processes both in terms of their kinetic behavior and their mechanisms of interaction with foods. The kinetics of microwave and conventional thermal inactivation are considered for a generalized nth-order model based on time and temperature conditions. However, thermal inactivation effects are often modeled by 1st-order kinetics. Microbial and nutrient inactivation by ionizing sources are considered for a 1st-order model based on radiation dose. Both thermal and radiation resistance concepts are reviewed and some typical values of radiation resistance are given for sensitive vegetative bacterial cells, yeasts, and molds and for resistant bacterial spores and viruses. Nonionizing microwave energy sources are increasingly used in home and industrial food processing and are well-accepted by the American public. But, despite recent Food and Drug Administration approval of low and intermediate ionizing radiation dose levels for grains and other plants products and the fact that irradiated foods are sold in more than 20 countries of the world, public fears in the U.S. about nuclear energy may limit the role of ionizing radiation in food processing and preservation and may also limit the use of nuclear fuels as an alternate source of electrical energy.

Landslide development within the Barlad Plateau of Eastern Romania

NASA Astrophysics Data System (ADS)

Niacsu, Lilian; Ionita, Ion

2014-05-01

The Barlad Plateau, extending about 8,230 square kilometers is considered as the most typical unit of the Moldavian Plateau of the Eastern Romania. The Miocene-Pliocene clay-sandy layers are inter-bedded with shallow sandstone and limestone seams. These sedimentary layers that have outcropped as a result of erosion are gently dipping toward S-SE in the form of a monocline. Landslides have been recognized as an important environmental threat in the major subunits of the Barlad Plateau, namely: Central Moldavian Plateau, Falciu Hills and Tutova Rolling Hills. Four main areas of monitoring landslides were explored such as successive aerial photographs of the 1960, 1970, 2005 and 2009 flights, repeated field surveys for a thorough reconnaissance of the study area, classical levelling work and GIS software applications as TNT Mips and Arc GIS. Also, the Caesium-137 technique has been used to get information on documenting sedimentation rates in some small catchments. Results have indicated that the landslide development is strongly controlled by the northern and western looking steep faces of cuestas, by changes of rock composition and by human impact. Also, it showed great pulses in conjunction with the rainfall distribution. For example, half of the Upper Barlad catchment that drains an area of 22,560 ha is covered by landslides. Furthermore, the active landslides amounted 11% of the total (2,317 ha) after the rainy 1968-1973 period and since 1982 under drier conditions they gradually limited to 444.0 ha (2% of the total).

Radioecological modelling of Polonium-210 and Caesium-137 in lichen-reindeer-man and top predators.

PubMed

Persson, Bertil R R; Gjelsvik, Runhild; Holm, Elis

2018-06-01

This work deals with analysis and modelling of the radionuclides 210 Pb and 210 Po in the food-chain lichen-reindeer-man in addition to 210 Po and 137 Cs in top predators. By using the methods of Partial Least Square Regression (PLSR) the atmospheric deposition of 210 Pb and 210 Po is predicted at the sample locations. Dynamic modelling of the activity concentration with differential equations is fitted to the sample data. Reindeer lichen consumption, gastrointestinal absorption, organ distribution and elimination is derived from information in the literature. Dynamic modelling of transfer of 210 Pb and 210 Po to reindeer meat, liver and bone from lichen consumption, fitted well with data from Sweden and Finland from 1966 to 1971. The activity concentration of 210 Pb in the skeleton in man is modelled by using the results of studying the kinetics of lead in skeleton and blood in lead-workers after end of occupational exposure. The result of modelling 210 Pb and 210 Po activity in skeleton matched well with concentrations of 210 Pb and 210 Po in teeth from reindeer-breeders and autopsy bone samples in Finland. The results of 210 Po and 137 Cs in different tissues of wolf, wolverine and lynx previously published, are analysed with multivariate data processing methods such as Principal Component Analysis PCA, and modelled with the method of Projection to Latent Structures, PLS, or Partial Least Square Regression PLSR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Frequency Comparison of [Formula: see text] Ion Optical Clocks at PTB and NPL via GPS PPP.

PubMed

Leute, J; Huntemann, N; Lipphardt, B; Tamm, Christian; Nisbet-Jones, P B R; King, S A; Godun, R M; Jones, J M; Margolis, H S; Whibberley, P B; Wallin, A; Merimaa, M; Gill, P; Peik, E

2016-07-01

We used precise point positioning, a well-established GPS carrier-phase frequency transfer method to perform a direct remote comparison of two optical frequency standards based on single laser-cooled [Formula: see text] ions operated at the National Physical Laboratory (NPL), U.K. and the Physikalisch-Technische Bundesanstalt (PTB), Germany. At both institutes, an active hydrogen maser serves as a flywheel oscillator which is connected to a GPS receiver as an external frequency reference and compared simultaneously to a realization of the unperturbed frequency of the (2)S1/2(F=0)-(2)D3/2(F=2) electric quadrupole transition in [Formula: see text] via an optical femtosecond frequency comb. To profit from long coherent GPS-link measurements, we extrapolate the fractional frequency difference over the various data gaps in the optical clock to maser comparisons which introduces maser noise to the frequency comparison but improves the uncertainty from the GPS-link instability. We determined the total statistical uncertainty consisting of the GPS-link uncertainty and the extrapolation uncertainties for several extrapolation schemes. Using the extrapolation scheme with the smallest combined uncertainty, we find a fractional frequency difference [Formula: see text] of -1.3×10(-15) with a combined uncertainty of 1.2×10(-15) for a total measurement time of 67 h. This result is consistent with an agreement of the frequencies realized by both optical clocks and with recent absolute frequency measurements against caesium fountain clocks within the corresponding uncertainties.

Effect of simple solutes on the long range dipolar correlations in liquid water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baul, Upayan, E-mail: upayanb@imsc.res.in; Anishetty, Ramesh, E-mail: ramesha@imsc.res.in; Vemparala, Satyavani, E-mail: vani@imsc.res.in

2016-03-14

Intermolecular correlations in liquid water at ambient conditions have generally been characterized through short range density fluctuations described through the atomic pair distribution functions. Recent numerical and experimental results have suggested that such a description of order or structure in liquid water is incomplete and there exist considerably longer ranged orientational correlations in water that can be studied through dipolar correlations. In this study, using large scale classical, atomistic molecular dynamics simulations using TIP4P-Ew and TIP3P models of water, we show that salts such as sodium chloride (NaCl), potassium chloride (KCl), caesium chloride (CsCl), and magnesium chloride (MgCl{sub 2}) havemore » a long range effect on the dipolar correlations, which cannot be explained by the notion of structure making and breaking by dissolved ions. Observed effects are explained through orientational stratification of water molecules around ions and their long range coupling to the global hydrogen bond network by virtue of the sum rule for water. The observations for single hydrophilic solutes are contrasted with the same for a single methane (CH{sub 4}) molecule. We observe that even a single small hydrophobe can result in enhancement of long range orientational correlations in liquid water, contrary to the case of dissolved ions, which have been observed to have a reducing effect. The observations from this study are discussed in the context of hydrophobic effect.« less

Fukushima fallout at Milano, Italy.

PubMed

Ioannidou, Alexandra; Manenti, Simone; Gini, Luigi; Groppi, Flavia

2012-12-01

The radionuclides (131)I, (137)Cs and (134)Cs were observed in the Milano region (45°) of Italy early after the nuclear accident in Fukushima, Japan. Increased atmospheric radioactivity was observed on an air filter taken on 30 March 2011, while the maximum activity of 467 μBq m(-3) for (131)I was recorded at April 3-4, 2011. The first evidence of Fukushima fallout was confirmed with (131)I and (137)Cs measured in precipitation at two sampling sites at Milano on 28 March, 2011, with the concentrations of (131)I and (137)Cs in the rainwater equal to 0.89 Bq L(-1) and 0.12 Bq L(-1), respectively. A sample of dry deposition that was collected 9 days after the first rainfall event of 27-28 March, 2011 showed that the dry deposition was more effective in the case of (137)Cs than it was for (131)I, probably because iodine was mainly in gaseous form whereas caesium was rapidly bound to aerosols and thus highly subject to dry deposition. The relatively high observed values of (137)Cs in grass, soil and fresh goat and cow milk samples were probably from Chernobyl fallout and global fallout from past nuclear tests rather than from the Fukushima accident. Finally, a dose assessment for the region of investigation showed clearly that the detected activities in all environmental samples were very far below levels of concern. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cost-effective sampling of (137)Cs-derived net soil redistribution: part 2 - estimating the spatial mean change over time.

PubMed

Chappell, A; Li, Y; Yu, H Q; Zhang, Y Z; Li, X Y

2015-06-01

The caesium-137 ((137)Cs) technique for estimating net, time-integrated soil redistribution by the processes of wind, water and tillage is increasingly being used with repeated sampling to form a baseline to evaluate change over small (years to decades) timeframes. This interest stems from knowledge that since the 1950s soil redistribution has responded dynamically to different phases of land use change and management. Currently, there is no standard approach to detect change in (137)Cs-derived net soil redistribution and thereby identify the driving forces responsible for change. We outline recent advances in space-time sampling in the soil monitoring literature which provide a rigorous statistical and pragmatic approach to estimating the change over time in the spatial mean of environmental properties. We apply the space-time sampling framework, estimate the minimum detectable change of net soil redistribution and consider the information content and cost implications of different sampling designs for a study area in the Chinese Loess Plateau. Three phases (1954-1996, 1954-2012 and 1996-2012) of net soil erosion were detectable and attributed to well-documented historical change in land use and management practices in the study area and across the region. We recommend that the design for space-time sampling is considered carefully alongside cost-effective use of the spatial mean to detect and correctly attribute cause of change over time particularly across spatial scales of variation. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simulation of RF power and multi-cusp magnetic field requirement for H- ion sources

NASA Astrophysics Data System (ADS)

Pathak, Manish; Senecha, V. K.; Kumar, Rajnish; Ghodke, Dharmraj. V.

2016-12-01

A computer simulation study for multi-cusp RF based H- ion source has been carried out using energy and particle balance equation for inductively coupled uniformly dense plasma considering sheath formation near the boundary wall of the plasma chamber for RF ion source used as high current injector for 1 Gev H- Linac project for SNS applications. The average reaction rates for different reactions responsible for H- ion production and destruction have been considered in the simulation model. The RF power requirement for the caesium free H- ion source for a maximum possible H- ion beam current has been derived by evaluating the required current and RF voltage fed to the coil antenna using transformer model for Inductively Coupled Plasma (ICP). Different parameters of RF based H- ion source like excited hydrogen molecular density, H- ion density, RF voltage and current of RF antenna have been calculated through simulations in the presence and absence of multicusp magnetic field to distinctly observe the effect of multicusp field. The RF power evaluated for different H- ion current values have been compared with the experimental reported results showing reasonably good agreement considering the fact that some RF power will be reflected from the plasma medium. The results obtained have helped in understanding the optimum field strength and field free regions suitable for volume emission based H- ion sources. The compact RF ion source exhibits nearly 6 times better efficiency compare to large diameter ion source.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dell'Erba, Giorgio; Natali, Dario; Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano

Ambipolar semiconducting polymers, characterized by both high electron (μ{sub e}) and hole (μ{sub h}) mobility, offer the advantage of realizing complex complementary electronic circuits with a single semiconducting layer, deposited by simple coating techniques. However, to achieve complementarity, one of the two conduction paths in transistors has to be suppressed, resulting in unipolar devices. Here, we adopt charge injection engineering through a specific interlayer in order to tune injection into frontier energy orbitals of a high mobility donor-acceptor co-polymer. Starting from field-effect transistors with Au contacts, showing a p-type unbalanced behaviour with μ{sub h} = 0.29 cm{sup 2}/V s and μ{sub e} = 0.001more » cm{sup 2}/V s, through the insertion of a caesium salt interlayer with optimized thickness, we obtain an n-type unbalanced transistor with μ{sub e} = 0.12 cm{sup 2}/V s and μ{sub h} = 8 × 10{sup −4} cm{sup 2}/V s. We applied this result to the development of the basic pass-transistor logic building blocks such as inverters, with high gain and good noise margin, and transmission-gates. In addition, we developed and characterized information storage circuits like D-Latches and D-Flip-Flops consisting of 16 transistors, demonstrating both their static and dynamic performances and thus the suitability of this technology for more complex circuits such as display addressing logic.« less

Estimation of the time-dependent radioactive source-term from the Fukushima nuclear power plant accident using atmospheric transport modelling

NASA Astrophysics Data System (ADS)

Schoeppner, M.; Plastino, W.; Budano, A.; De Vincenzi, M.; Ruggieri, F.

2012-04-01

Several nuclear reactors at the Fukushima Dai-ichi power plant have been severely damaged from the Tōhoku earthquake and the subsequent tsunami in March 2011. Due to the extremely difficult on-site situation it has been not been possible to directly determine the emissions of radioactive material. However, during the following days and weeks radionuclides of 137-Caesium and 131-Iodine (amongst others) were detected at monitoring stations throughout the world. Atmospheric transport models are able to simulate the worldwide dispersion of particles accordant to location, time and meteorological conditions following the release. The Lagrangian atmospheric transport model Flexpart is used by many authorities and has been proven to make valid predictions in this regard. The Flexpart software has first has been ported to a local cluster computer at the Grid Lab of INFN and Department of Physics of University of Roma Tre (Rome, Italy) and subsequently also to the European Mediterranean Grid (EUMEDGRID). Due to this computing power being available it has been possible to simulate the transport of particles originating from the Fukushima Dai-ichi plant site. Using the time series of the sampled concentration data and the assumption that the Fukushima accident was the only source of these radionuclides, it has been possible to estimate the time-dependent source-term for fourteen days following the accident using the atmospheric transport model. A reasonable agreement has been obtained between the modelling results and the estimated radionuclide release rates from the Fukushima accident.

A Monte Carlo investigation of lung brachytherapy treatment planning

NASA Astrophysics Data System (ADS)

Sutherland, J. G. H.; Furutani, K. M.; Thomson, R. M.

2013-07-01

Iodine-125 (125I) and Caesium-131 (131Cs) brachytherapy have been used in conjunction with sublobar resection to reduce the local recurrence of stage I non-small cell lung cancer compared with resection alone. Treatment planning for this procedure is typically performed using only a seed activity nomogram or look-up table to determine seed strand spacing for the implanted mesh. Since the post-implant seed geometry is difficult to predict, the nomogram is calculated using the TG-43 formalism for seeds in a planar geometry. In this work, the EGSnrc user-code BrachyDose is used to recalculate nomograms using a variety of tissue models for 125I and 131Cs seeds. Calculated prescription doses are compared to those calculated using TG-43. Additionally, patient CT and contour data are used to generate virtual implants to study the effects that post-implant deformation and patient-specific tissue heterogeneity have on perturbing nomogram-derived dose distributions. Differences of up to 25% in calculated prescription dose are found between TG-43 and Monte Carlo calculations with the TG-43 formalism underestimating prescription doses in general. Differences between the TG-43 formalism and Monte Carlo calculated prescription doses are greater for 125I than for 131Cs seeds. Dose distributions are found to change significantly based on implant deformation and tissues surrounding implants for patient-specific virtual implants. Results suggest that accounting for seed grid deformation and the effects of non-water media, at least approximately, are likely required to reliably predict dose distributions in lung brachytherapy patients.

Atmospheric emissions from the Windscale accident of October 1957

NASA Astrophysics Data System (ADS)

Garland, J. A.; Wakeford, R.

Although it occurred nearly 50 years ago, the nuclear reactor fire of October 1957 at Windscale Works, Sellafield, England, continues to attract interest. Several attempts have been made to quantify the releases of radionuclides and their radiological consequences, but additional information and a re-analysis of meteorological data encourage a further examination of emissions. The limited instrumentation of the reactor provided little relevant information and, as in previous estimates, the discharges are deduced from environmental evidence, but here the recent meteorological analysis is used. The interpretation of the meteorological and environmental evidence requires both timing and quantity of the emitted radionuclides to be considered together. Significant fission product emission continued from about 15:00 or 16:00 on 10 October 1957 until noon the following day. There were two main peaks in discharge rate, during the evening and early hours and from roughly 06:00 until 10:30, and the amounts emitted during each of these periods were probably comparable. Iodine-131 ( 131I), caesium-137 ( 137Cs) and polonium-210 ( 210Po) activities dominated the radioactive emissions and there is sufficient environmental evidence for releases of these radionuclides to be estimated within a factor of about two. (Some additional 131I may have escaped in a chemical form that was not included in the estimate, but it appears likely that the fraction was small.) There is evidence that the plume extended further east than accepted in previous assessments and the estimates of quantities emitted have been increased to allow for this. For other radionuclides the environmental measurements were fewer and the uncertainties are greater.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joseph, Kitheri; Stennett, Martin C.; Hyatt, Neil C.

Bulk properties such as glass transition temperature, density and thermal expansion of iron phosphate glass compositions, with replacement of Cs by Ba, are investigated as a surrogate for the transmutation of 137Cs to 137Ba, relevant to the immobilisation of Cs in glass. These studies are required to establish the appropriate incorporation rate of 137Cs in iron phosphate glass. Density and glass transition temperature increases with the addition of BaO indicating the shrinkage and reticulation of the iron phosphate glass network. The average thermal expansion coefficient reduces from 19.8 × 10-6 K-1 to 13.4 × 10-6 K-1, when 25 wt. %more » of Cs2O was replaced by 25 wt. % of BaO in caesium loaded iron phosphate glass. In addition to the above bulk properties, the role of Ba as a network modifier in the structure of iron phosphate glass is examined using various spectroscopic techniques. The FeII content and average coordination number of iron in the glass network was estimated using Mössbauer spectroscopy. The FeII content in the un-doped iron phosphate glass and barium doped iron phosphate glasses was 20, 21 and 22 ± 1% respectively and the average Fe coordination varied from 5.3 ± 0.2 to 5.7 ± 0.2 with increasing Ba content. The atomic scale structure was further probed by Fe K-edge X-ray absorption spectroscopy. The average coordination number provided by extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge structure was in good agreement with that given by the Mössbauer data.« less

Alkali metal complexes of a phosphine-borane-stabilised carbanion: influence of co-ligands on structure.

PubMed

Izod, Keith; Wills, Corinne; Clegg, William; Harrington, Ross W

2007-09-07

The adducts [[(Me(3)Si)(2){Me(2)P(BH(3))}C]K(L)(n)](m) [L = THF, n = 0.5, m = infinity (2a); L = tmeda (2b), pmdeta (2c), n = 1, m = 2] may be synthesised by treatment of solvent-free [[(Me(3)Si)(2){Me(2)P(BH(3))}C]K](infinity) (2) with the corresponding Lewis base (tmeda = N,N,N',N'-tetramethylethylenediamine; pmdeta = N,N,N',N'',N''-pentamethyldiethylenetriamine). X-Ray crystallography reveals that, whereas 2 crystallises with a complex 2-dimensional sheet structure, 2a crystallises as a ribbon-type one-dimensional polymer and both 2b and 2c crystallise as dimers. The corresponding complex with 12-crown-4, [K(12-crown-4)(2)][(Me(3)Si)(2){Me(2)P(BH(3))}C] (2d) crystallises as a separated ion pair. The complexes [[(Me(3)Si)(2){Me(2)P(BH(3))}C]M(pmdeta)](n) [M = Na, n = 1 (6); M = Rb, n = 2 (7)] may be synthesised by treatment of [(Me(3)Si)(2){Me(2)P(BH(3))}C]M with pmdeta. Whereas crystallises as a discrete monomer, compound 7 crystallises as a dimer. Compounds 2, 2a-2d, 6, 7 and the corresponding caesium derivative [[(Me(3)Si)(2){Me(2)P(BH(3))}C]Cs(pmdeta)](2) () provide an opportunity to consider the influence of the ionic radius of the metal and the nature of the co-ligands on the structures of alkali metal complexes of a phosphine-borane-stabilised carbanion.

Carbon dioxide utilization via carbonate-promoted C-H carboxylation.

PubMed

Banerjee, Aanindeeta; Dick, Graham R; Yoshino, Tatsuhiko; Kanan, Matthew W

2016-03-10

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO3(2-)) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)--a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO3(2-)-promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

On the occurrence of metallic character in the periodic table of the chemical elements.

PubMed

Hensel, Friedrich; Slocombe, Daniel R; Edwards, Peter P

2015-03-13

The classification of a chemical element as either 'metal' or 'non-metal' continues to form the basis of an instantly recognizable, universal representation of the periodic table (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23; Poliakoff M. & Tang S. 2015 Phil. Trans. R. Soc. A 373: , 20140211). Here, we review major, pre-quantum-mechanical innovations (Goldhammer DA. 1913 Dispersion und Absorption des Lichtes; Herzfeld KF. 1927 Phys. Rev. 29: , 701-705) that allow an understanding of the metallic or non-metallic status of the chemical elements under both ambient and extreme conditions. A special emphasis will be placed on recent experimental advances that investigate how the electronic properties of chemical elements vary with temperature and density, and how this invariably relates to a changing status of the chemical elements. Thus, the prototypical non-metals, hydrogen and helium, becomes metallic at high densities; and the acknowledged metals, mercury, rubidium and caesium, transform into their non-metallic forms at low elemental densities. This reflects the fundamental fact that, at temperatures above the absolute zero of temperature, there is therefore no clear dividing line between metals and non-metals. Our conventional demarcation of chemical elements as metals or non-metals within the periodic table is of course governed by our experience of the nature of the elements under ambient conditions. Examination of these other situations helps us to examine the exact divisions of the chemical elements into metals and non-metals (Mendeleeff D. 1905 The principles of chemistry, vol. II, p. 23). © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Spectroscopic (FT-IR, FT-Raman, UV absorption, 1H and 13C NMR) and theoretical (in B3LYP/6-311++G** level) studies on alkali metal salts of caffeic acid.

PubMed

Świsłocka, Renata

2013-01-01

The effect of some metals on the electronic system of benzoic and nicotinic acids has recently been investigated by IR, Raman and UV spectroscopy [1-3]. Benzoic and nicotinic acids are regarded model systems representing a wide group of aromatic ligands which are incorporated into enzymes. In this work the FT-IR (in solid state and in solution), FT-Raman, UV absorption and (1)H and (13)C NMR spectra of caffeic acid (3,4-dihydroxycinnamic acid) and its salts with lithium, sodium, potassium, rubidium and caesium were registered, assigned and analyzed. The effect of alkali metals on the electronic system of ligands was discussed. Studies of differences in the number and position of bands from the IR, Raman, UV absorption spectra and chemical shifts from NMR spectra allowed to conclude on the distribution of electronic charge in the molecules, the delocalization energy of π electrons and the reactivity of ligands in metal complexes. Optimized geometrical structures of studied compounds were calculated by B3LYP method using 6-311++G** basis set. Bond lengths, angles and dipole moments for the optimized structures of caffeic acid and lithium, sodium, potassium caffeinates were also calculated. The theoretical wavenumbers and intensities of IR spectra were obtained. The calculated parameters were compared to the experimental characteristics of investigated compounds. Microbial activity of studied compounds was tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Proteus vulgaris. Copyright © 2012 Elsevier B.V. All rights reserved.

Demand driven salt clean-up in a molten salt fast reactor - Defining a priority list.

PubMed

Merk, B; Litskevich, D; Gregg, R; Mount, A R

2018-01-01

The PUREX technology based on aqueous processes is currently the leading reprocessing technology in nuclear energy systems. It seems to be the most developed and established process for light water reactor fuel and the use of solid fuel. However, demand driven development of the nuclear system opens the way to liquid fuelled reactors, and disruptive technology development through the application of an integrated fuel cycle with a direct link to reactor operation. The possibilities of this new concept for innovative reprocessing technology development are analysed, the boundary conditions are discussed, and the economic as well as the neutron physical optimization parameters of the process are elucidated. Reactor physical knowledge of the influence of different elements on the neutron economy of the reactor is required. Using an innovative study approach, an element priority list for the salt clean-up is developed, which indicates that separation of Neodymium and Caesium is desirable, as they contribute almost 50% to the loss of criticality. Separating Zirconium and Samarium in addition from the fuel salt would remove nearly 80% of the loss of criticality due to fission products. The theoretical study is followed by a qualitative discussion of the different, demand driven optimization strategies which could satisfy the conflicting interests of sustainable reactor operation, efficient chemical processing for the salt clean-up, and the related economic as well as chemical engineering consequences. A new, innovative approach of balancing the throughput through salt processing based on a low number of separation process steps is developed. Next steps for the development of an economically viable salt clean-up process are identified.

Iron phosphate glasses: Bulk properties and atomic scale structure

NASA Astrophysics Data System (ADS)

Joseph, Kitheri; Stennett, Martin C.; Hyatt, Neil C.; Asuvathraman, R.; Dube, Charu L.; Gandy, Amy S.; Govindan Kutty, K. V.; Jolley, Kenny; Vasudeva Rao, P. R.; Smith, Roger

2017-10-01

Bulk properties such as glass transition temperature, density and thermal expansion of iron phosphate glass compositions, with replacement of Cs by Ba, are investigated as a surrogate for the transmutation of 137Cs to 137Ba, relevant to the immobilisation of Cs in glass. These studies are required to establish the appropriate incorporation rate of 137Cs in iron phosphate glass. Density and glass transition temperature increases with the addition of BaO indicating the shrinkage and reticulation of the iron phosphate glass network. The average thermal expansion coefficient reduces from 19.8 × 10-6 K-1 to 13.4 × 10-6 K-1, when 25 wt. % of Cs2O was replaced by 25 wt. % of BaO in caesium loaded iron phosphate glass. In addition to the above bulk properties, the role of Ba as a network modifier in the structure of iron phosphate glass is examined using various spectroscopic techniques. The FeII content and average coordination number of iron in the glass network was estimated using Mössbauer spectroscopy. The FeII content in the un-doped iron phosphate glass and barium doped iron phosphate glasses was 20, 21 and 22 ± 1% respectively and the average Fe coordination varied from 5.3 ± 0.2 to 5.7 ± 0.2 with increasing Ba content. The atomic scale structure was further probed by Fe K-edge X-ray absorption spectroscopy. The average coordination number provided by extended X-ray absorption fine structure spectroscopy and X-ray absorption near edge structure was in good agreement with that given by the Mössbauer data.

First international comparison of fountain primary frequency standards via a long distance optical fiber link

NASA Astrophysics Data System (ADS)

Guéna, J.; Weyers, S.; Abgrall, M.; Grebing, C.; Gerginov, V.; Rosenbusch, P.; Bize, S.; Lipphardt, B.; Denker, H.; Quintin, N.; Raupach, S. M. F.; Nicolodi, D.; Stefani, F.; Chiodo, N.; Koke, S.; Kuhl, A.; Wiotte, F.; Meynadier, F.; Camisard, E.; Chardonnet, C.; Le Coq, Y.; Lours, M.; Santarelli, G.; Amy-Klein, A.; Le Targat, R.; Lopez, O.; Pottie, P. E.; Grosche, G.

2017-06-01

We report on the first comparison of distant caesium fountain primary frequency standards (PFSs) via an optical fiber link. The 1415 km long optical link connects two PFSs at LNE-SYRTE (Laboratoire National de métrologie et d’Essais—SYstème de Références Temps-Espace) in Paris (France) with two at PTB (Physikalisch-Technische Bundesanstalt) in Braunschweig (Germany). For a long time, these PFSs have been major contributors to accuracy of the International Atomic Time (TAI), with stated accuracies of around 3× {{10}-16} . They have also been the references for a number of absolute measurements of clock transition frequencies in various optical frequency standards in view of a future redefinition of the second. The phase coherent optical frequency transfer via a stabilized telecom fiber link enables far better resolution than any other means of frequency transfer based on satellite links. The agreement for each pair of distant fountains compared is well within the combined uncertainty of a few 10-16 for all the comparisons, which fully supports the stated PFSs’ uncertainties. The comparison also includes a rubidium fountain frequency standard participating in the steering of TAI and enables a new absolute determination of the 87Rb ground state hyperfine transition frequency with an uncertainty of 3.1× {{10}-16} . This paper is dedicated to the memory of André Clairon, who passed away on 24 December 2015, for his pioneering and long-lasting efforts in atomic fountains. He also pioneered optical links from as early as 1997.

Study and optimisation of SIMS performed with He+ and Ne+ bombardment

NASA Astrophysics Data System (ADS)

Pillatsch, L.; Vanhove, N.; Dowsett, D.; Sijbrandij, S.; Notte, J.; Wirtz, T.

2013-10-01

The combination of the high-brightness He+/Ne+ atomic level ion source with the detection capabilities of secondary ion mass spectrometry (SIMS) opens up the prospect of obtaining chemical information with high lateral resolution and high sensitivity on the Zeiss ORION helium ion microscope (HIM). A feasibility study with He+ and Ne+ ion bombardment is presented in order to determine the performance of SIMS analyses using the HIM. Therefore, the sputtering yields, useful yields and detection limits obtained for metallic (Al, Ni and W) as well as semiconductor samples (Si, Ge, GaAs and InP) were investigated. All the experiments were performed on a Cameca IMS4f SIMS instrument which was equipped with a caesium evaporator and oxygen flooding system. For most of the elements, useful yields in the range of 10-4 to 3 × 10-2 were measured with either O2 or Cs flooding. SIMS experiments performed directly on the ORION with a prototype secondary ion extraction and detection system lead to results that are consistent with those obtained on the IMS4f. Taking into account the obtained useful yields and the analytical conditions, such as the ion current and typical dwell time on the ORION HIM, detection limits in the at% range and better can be obtained during SIMS imaging at 10 nm lateral resolution with Ne+ bombardment and down to the ppm level when a lateral resolution of 100 nm is chosen. Performing SIMS on the HIM with a good detection limit while maintaining an excellent lateral resolution (<50 nm) is therefore very promising.

Study of leaching mechanisms of caesium ions incorporated in Ordinary Portland Cement.

PubMed

Papadokostaki, Kyriaki G; Savidou, Anastasia

2009-11-15

In this work, a study of the leaching kinetics of Cs(+) ions from cement paste solids, containing inactive Cs(2)SO(4), is presented, involving (i) the parallel performance of leaching experiments at two temperatures (30 degrees C and 70 degrees C); (ii) the performance of leaching tests with intermediate changes in temperature between 30 degrees C and 70 degrees C; (iii) the use of specimens of two different thicknesses and (iv) the determination of the distribution of Cs(+) in the cement specimen at various stages of the leaching test. The results of leaching studies at 30 degrees C with cement solids simulating the composition of real radioactive wastes, containing NaNO(3), small amounts of inactive CsNO(3) and traces of (137)Cs(+) are also reported. Concentration profiles of Cs(+) in inactive specimens showed that part of the Cs(+) (20-30%) tends to be immobilized in the matrix, while elution of the readily leachable portion follows Fick's law reasonably well. No immobilized Cs(+) was detected in the samples containing considerable amounts of NaNO(3). Long-term leaching experiments (up to 8 years) revealed acceleration of the elution process (not detectable in short-term tests), attributable to increase in porosity caused by erosion of the cement matrix. Sorption experiments of Cs(+) ions by cement granules indicated that adsorption on cement pore surfaces is not significant. On the other hand, the leaching tests at two different temperatures or with intermediate changes in temperature between 30 degrees C and 70 degrees C, yielded activation energies that indicated a more complicated kinetic behavior.

Simultaneous measurements of work function and H‒ density including caesiation of a converter surface

NASA Astrophysics Data System (ADS)

Cristofaro, S.; Friedl, R.; Fantz, U.

2017-08-01

Negative hydrogen ion sources rely on the surface conversion of neutral atomic hydrogen and positive hydrogen ions to H-. The efficiency of this process depends on the actual work function of the converter surface. By introducing caesium into the source the work function decreases, enhancing the negative ion yield. In order to study the impact of the work function on the H- surface production at similar conditions to the ones in ion sources for fusion devices like ITER and DEMO, fundamental investigations are performed in a flexible laboratory experiment. The work function of the converter surface can be absolutely measured by photoelectric effect, while a newly installed cavity ring-down spectroscopy system (CRDS) measures the H- density. The CRDS is firstly tested and characterized by investigations on H- volume production. Caesiation of a stainless steel sample is then performed in vacuum and the plasma effect on the Cs layer is investigated also for long plasma-on times. A minimum work function of (1.9±0.1) eV is reached after some minutes of plasma treatment, resulting in a reduction by a value of 0.8 eV compared to vacuum measurements. The H- density above the surface is (2.1±0.5)×1015 m-3. With further plasma exposure of the caesiated surface, the work function increases up to 3.75 eV, due to the impinging plasma particles which gradually remove the Cs layer. As a result, the H- density decreases by a factor of at least 2.

The use of 137Cs to establish longer-term soil erosion rates on footpaths in the UK.

PubMed

Rodway-Dyer, S J; Walling, D E

2010-10-01

There is increasing awareness of the damage caused to valuable and often unique sensitive habitats by people pressure as degradation causes a loss of plant species, disturbance to wildlife, on-site and off-site impacts of soil movement and loss, and visual destruction of pristine environments. This research developed a new perspective on the problem of recreational induced environmental degradation by assessing the physical aspects of soil erosion using the fallout radionuclide caesium-137 ((137)Cs). Temporal sampling problems have not successfully been overcome by traditional research methods monitoring footpath erosion and, to date, the (137)Cs technique has not been used to estimate longer-term soil erosion in regard to sensitive recreational habitats. The research was based on-sites within Dartmoor National Park (DNP) and the South West Coast Path (SWCP) in south-west England. (137)Cs inventories were reduced on the paths relative to the reference inventory (control), indicating loss of soil from the path areas. The Profile Distribution Model estimated longer-term erosion rates (ca. 40 years) based on the (137)Cs data and showed that the combined mean soil loss for all the sites on 'paths' was 1.41 kg m(-2) yr(-1) whereas the combined 'off path' soil loss was 0.79 kg m(-2) yr(-1), where natural (non-recreational) soil redistribution processes occur. Recreational pressure was shown to increase erosion in the long-term, as greater soil erosion occurred on the paths, especially where there was higher visitor pressure. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Carbon dioxide utilization via carbonate-promoted C-H carboxylation

NASA Astrophysics Data System (ADS)

Banerjee, Aanindeeta; Dick, Graham R.; Yoshino, Tatsuhiko; Kanan, Matthew W.

2016-03-01

Using carbon dioxide (CO2) as a feedstock for commodity synthesis is an attractive means of reducing greenhouse gas emissions and a possible stepping-stone towards renewable synthetic fuels. A major impediment to synthesizing compounds from CO2 is the difficulty of forming carbon-carbon (C-C) bonds efficiently: although CO2 reacts readily with carbon-centred nucleophiles, generating these intermediates requires high-energy reagents (such as highly reducing metals or strong organic bases), carbon-heteroatom bonds or relatively acidic carbon-hydrogen (C-H) bonds. These requirements negate the environmental benefit of using CO2 as a substrate and limit the chemistry to low-volume targets. Here we show that intermediate-temperature (200 to 350 degrees Celsius) molten salts containing caesium or potassium cations enable carbonate ions (CO32-) to deprotonate very weakly acidic C-H bonds (pKa > 40), generating carbon-centred nucleophiles that react with CO2 to form carboxylates. To illustrate a potential application, we use C-H carboxylation followed by protonation to convert 2-furoic acid into furan-2,5-dicarboxylic acid (FDCA)—a highly desirable bio-based feedstock with numerous applications, including the synthesis of polyethylene furandicarboxylate (PEF), which is a potential large-scale substitute for petroleum-derived polyethylene terephthalate (PET). Since 2-furoic acid can readily be made from lignocellulose, CO32--promoted C-H carboxylation thus reveals a way to transform inedible biomass and CO2 into a valuable feedstock chemical. Our results provide a new strategy for using CO2 in the synthesis of multi-carbon compounds.

Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

NASA Astrophysics Data System (ADS)

Stohl, A.; Seibert, P.; Wotawa, G.; Arnold, D.; Burkhart, J. F.; Eckhardt, S.; Tapia, C.; Vargas, A.; Yasunari, T. J.

2012-04-01

This presentation will show the results of a paper currently under review in ACPD and some additional new results, including more data and with an independent box modeling approach to support some of the findings of the ACPD paper. On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant (FD-NPP) developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined the first guess with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 16.7 (uncertainty range 13.4-20.0) EBq, which is the largest radioactive noble gas release in history not associated with nuclear bomb testing. There is strong evidence that the first strong 133Xe release started early, before active venting was performed. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. For 137Cs, the inversion results give a total emission of 35.8 (23.3-50.1) PBq, or about 42% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude exactly when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions were not only coming from the damaged reactor cores, but also from the spent-fuel pool of unit 4 and confirms that the spraying was an effective countermeasure. We also explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. The plume was also dispersed quickly over the entire Northern Hemisphere, first reaching North America on 15 March and Europe on 22 March. In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement with each other. Altogether, we estimate that 6.4 PBq of 137Cs, or 19% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 PBq, or 2% of the total fallout were deposited on land areas other than Japan.

From {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} to {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite chains in A{sub 6}U{sub 2}Mo{sub 4}O{sub 21} (A=Na, K, Rb, Cs) compounds: Synthesis and crystal structure of Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yagoubi, S.; Groupe de Radiochimie, Institut de Physique Nucleaire d'Orsay, Universite Paris-Sud XI, 91406 Orsay Cedex; Obbade, S., E-mail: said.obbade@phelma.grenoble-inp.f

2011-05-15

A new caesium uranyl molybdate belonging to the M{sub 6}U{sub 2}Mo{sub 4}O{sub 21} family has been synthesized by solid-state reaction and its structure determined from single-crystal X-ray diffraction data. Contrary to the other alkali uranyl molybdates of this family (A=Na, K, Rb) where molybdenum atoms adopt only tetrahedral coordination and which can be formulated A{sub 6}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}], the caesium compound Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 21} should be written Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] with molybdenum atoms in tetrahedral and square pyramidal environments. Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] crystallizes in the triclinic symmetry withmore » space group P1-bar and a=10.4275(14) A, b=15.075(2) A, c=17.806(2) A, {alpha}=70.72(1){sup o}, {beta}=80.38(1){sup o} and {gamma}=86.39(1){sup o}, V=2604.7(6) A{sup 3}, Z=4, {rho}{sub mes}=5.02(2) g/cm{sup 3} and {rho}{sub cal}=5.08(3) g/cm{sup 3}. A full-matrix least-squares refinement on the basis of F{sup 2} yielded R{sub 1}=0.0464 and wR{sub 2}=0.0950 for 596 parameters with 6964 independent reflections with I{>=}2{sigma}(I) collected on a BRUKER AXS diffractometer with Mo(K{alpha}) radiation and a CCD detector. The crystal structure of Cs compound is characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} parallels chains built from U{sub 2}O{sub 13} dimeric units, MoO{sub 4} tetrahedra and MoO{sub 5} square pyramids, whereas, Na, K and Rb compounds are characterized by {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}O(MoO{sub 4}){sub 4}]{sup 6-} parallel chains formulated simply of U{sub 2}O{sub 13} units and MoO{sub 4} tetrahedra. Infrared spectroscopy measurements using powdered samples synthesized by solid-state reaction, confirm the structural results. The thermal stability and the electrical conductivity are also studied. The four compounds decompose at low temperature (between 540 and 610 {sup o}C). -- Graphical abstract: The staking of {sub {infinity}}{sup 1}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})]{sup 6-} infinite uranyl molybdate ribbons in the Cs{sub 6}[(UO{sub 2}){sub 2}(MoO{sub 4}){sub 3}(MoO{sub 5})] structure. Display Omitted Highlights: {yields} Cs{sub 6}U{sub 2}Mo{sub 4}O{sub 2} a new compound with bidimensional crystal structure, characterized by infinite uranyl molybdate chains. {yields} Crystal structure similar to these of the compounds containing Na, K, Rb. {yields} Molybdenum atoms surrounded by five oxygen atoms to form an original and strongly distorted MoO{sub 5} environment. {yields} The chains arrangement illustrates the key role of the alkaline ionic radius, in the crystal structure distortion for Cs compound.« less

Exposure from the Chernobyl accident had adverse effects on erythrocytes, leukocytes, and, platelets in children in the Narodichesky region, Ukraine: A 6-year follow-up study

PubMed Central

Stepanova, Eugenia; Karmaus, Wilfried; Naboka, Marina; Vdovenko, Vitaliy; Mousseau, Tim; Shestopalov, Viacheslav M; Vena, John; Svendsen, Erik; Underhill, Dwight; Pastides, Harris

2008-01-01

Background After the Chernobyl nuclear accident on April 26, 1986, all children in the contaminated territory of the Narodichesky region, Zhitomir Oblast, Ukraine, were obliged to participate in a yearly medical examination. We present the results from these examinations for the years 1993 to 1998. Since the hematopoietic system is an important target, we investigated the association between residential soil density of 137Caesium (137Cs) and hemoglobin concentration, and erythrocyte, platelet, and leukocyte counts in 1,251 children, using 4,989 repeated measurements taken from 1993 to 1998. Methods Soil contamination measurements from 38 settlements were used as exposures. Blood counts were conducted using the same auto-analyzer in all investigations for all years. We used linear mixed models to compensate for the repeated measurements of each child over the six year period. We estimated the adjusted means for all markers, controlling for potential confounders. Results Data show a statistically significant reduction in red and white blood cell counts, platelet counts and hemoglobin with increasing residential 137Cs soil contamination. Over the six-year observation period, hematologic markers did improve. In children with the higher exposure who were born before the accident, this improvement was more pronounced for platelet counts, and less for red blood cells and hemoglobin. There was no exposure×time interaction for white blood cell counts and not in 702 children who were born after the accident. The initial exposure gradient persisted in this sub-sample of children. Conclusion The study is the first longitudinal analysis from a large cohort of children after the Chernobyl accident. The findings suggest persistent adverse hematological effects associated with residential 137Cs exposure. PMID:18513393

Fibrotic-like changes in degenerate human intervertebral discs revealed by quantitative proteomic analysis.

PubMed

Yee, A; Lam, M P Y; Tam, V; Chan, W C W; Chu, I K; Cheah, K S E; Cheung, K M C; Chan, D

2016-03-01

Intervertebral disc degeneration (IDD) can lead to symptomatic conditions including sciatica and back pain. The purpose of this study is to understand the extracellular matrix (ECM) changes in disc biology through comparative proteomic analysis of degenerated and non-degenerated human intervertebral disc (IVD) tissues of different ages. Seven non-degenerated (11-46 years of age) and seven degenerated (16-53 years of age) annulus fibrosus (AF) and nucleus pulposus (NP) samples were used. Proteins were extracted using guanidine hydrochloride, separated from large proteoglycans (PGs) by caesium chloride (CsCl) density gradient ultracentrifugation, and identified using liquid chromatography (LC) coupled with tandem mass spectrometry (MS/MS). For quantitative comparison, proteins were labeled with iTRAQ reagents. Collagen fibrils in the NP were assessed using scanning electron microscopy (SEM). In the AF, quantitative analysis revealed increased levels of HTRA1, COMP and CILP in degeneration when compared with samples from older individuals. Fibronectin showed increment with age and degeneration. In the NP, more CILP and CILP2 were present in degenerated samples of younger individuals. Reduced protein solubility was observed in degenerated and older non-degenerated samples correlated with an accumulation of type I collagen in the insoluble fibers. Characterization of collagen fibrils in the NP revealed smaller mean fibril diameters and decreased porosity in the degenerated samples. Our study identified distinct matrix changes associated with aging and degeneration in the intervertebral discs (IVDs). The nature of the ECM changes, together with observed decreased in solubility and changes in fibril diameter is consistent with a fibrotic-like environment. Copyright © 2015 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

High-power Al-free active region (λ= 852nm) DFB laser diodes for atomic clocks and interferometry applications

NASA Astrophysics Data System (ADS)

Ligeret, V.; Vermersch, F.-J.; Bansropun, S.; Lecomte, M.; Calligaro, M.; Parillaud, O.; Krakowski, M.

2017-11-01

Atomic clocks will be used in the future European positioning system Galileo. Among them, the optically pumped clocks provide a better alternative with comparable accuracy for a more compact system. For these systems, diode lasers emitting at 852nm are strategic components. The laser in a conventional bench for atomic clocks presents disadvantages for spatial applications. A better approach would be to realise a system based on a distributed-feedback laser (DFB). We have developed the technological foundations of such lasers operating at 852nm. These include an Al free active region, a single spatial mode ridge waveguide and a DFB structure. The device is a separate confinement heterostructure with a GaInP large optical cavity and a single compressive strained GaInAsP quantum well. The broad area laser diodes are characterised by low internal losses (<3cm -1 ), a high internal efficiency (94%) and a low transparency current density (100A/cm2). For an AR-HR coated ridge Fabry Perot laser, we obtain a power of 230mW with M2=1.3. An optical power of 150mW was obtained at 854nm wavelength, 20°C for AR-HR coated devices. We obtain a single spatial mode emission with M2=1.21 and a SMSR over 30dB, both at 150mW. DFB Lasers at 852.12nm, corresponding to the D2 caesium transition, were then realised with a power of 40mW, 37°C for uncoated devices. The SMSR is over 30dB and the M2=1.33 at 40mW. Furthermore, the preliminary results of the linewidth obtained with a Fabry Perot interferometer give a value of less than 2MHz.

Total cancer incidence in relation to 137Cs fallout in the most contaminated counties in Sweden after the Chernobyl nuclear power plant accident: a register-based study

PubMed Central

Alinaghizadeh, Hassan; Wålinder, Robert; Vingård, Eva; Tondel, Martin

2016-01-01

Objectives To determine the total cancer incidence in relation to a 5-year exposure to caesium-137 (137Cs) from the 1986 Chernobyl nuclear power plant accident. Methods A closed cohort was defined as all individuals living in the three most contaminated counties in mid-Sweden in 1986. Fallout of 137Cs was retrieved as a digital map from the Geological Survey of Sweden, demographic data from Statistics Sweden, and cancer diagnosis from the National Board of Health and Welfare. Individuals were assigned an annual 137Cs exposure based on their place of residence (1986–1990), from which 5-year cumulative 137Cs exposures were calculated, accounting for the physical decay of 137Cs and changing residencies. HRs were adjusted for age, sex, rural/non-rural residence and pre-Chernobyl total cancer incidence. Results The 734 537 people identified were categorised by exposure: the first quartile was low exposure (0.0–45.4 kBq/m2), the second and third quartiles were intermediate exposure (45.41–118.8 kBq/m2), and the fourth quartile was the highest exposure (118.81–564.71 kBq/m2). Between 1991 and 2010, 82 495 cancer cases were registered in the 3 counties. Adjusted HRs (95% CI) were 1.03 (1.01 to 1.05) for intermediate exposure and 1.05 (1.03 to 1.07) for the highest exposure compared to the reference exposure. Conclusions We found a small overall exposure–response pattern of the total cancer incidence related to 137Cs after adjustment for age, sex, rural residence and pre-Chernobyl cancer incidence. PMID:27998898

Incorporating Cs and Sr into blast furnace slag inorganic polymers and their effect on matrix properties

NASA Astrophysics Data System (ADS)

Vandevenne, Niels; Iacobescu, Remus Ion; Pontikes, Yiannis; Carleer, Robert; Thijssen, Elsy; Gijbels, Katrijn; Schreurs, Sonja; Schroeyers, Wouter

2018-05-01

Minimizing harmful effects to the environment in waste-management practices requires continuous innovation. This is especially important in the field of radioactive waste management. Alternatives to the commonly used ordinary Portland cement matrices are being increasingly studied for improved immobilisation purposes. The development of inorganic polymers (IP) from industrial residues has been successfully studied for the immobilisation of caesium (Cs+) and strontium (Sr2+). However, knowledge of the effect of these introduced elements on the IP-matrix is scarce, especially considering that studied effects are dependent on the IP-precursor characteristics and the form in which the Cs+ and Sr2+ are introduced. In this study, IPs containing varying amounts of CsNO3 and Sr(NO3)2 were developed to study the effect of the introduced elements on the IP-characteristics. IP-samples were developed from ground granulated blast furnace slag (GGBFS) and 6 M NaOH activating solution. Cs+ and Sr2+ were added to account for 0.5, 1 and 2 wt% of the total IP-mass. Throughout the entire study, Cs+-addition showed no significant effects on the studied parameters. Calorimetric results showed that Sr2+ severely affects reaction kinetics, consuming hydroxide ions necessary for the alkali activation reaction. Sr2+-addition also caused a severe decrease in compressive strength, increased calcium leaching, and decreased sodium and hydroxide leaching. Micro-chemical analyses showed that Cs+ is almost fully incorporated in the formed IP-matrix, while Sr2+ mainly precipitates as Sr(OH)2 in concentrated regions throughout the IP-structure. The findings presented in this paper give insights on the effect of contaminant elements on the immobilising matrix.

Hydrogen suppresses UO 2 corrosion

NASA Astrophysics Data System (ADS)

Carbol, Paul; Fors, Patrik; Gouder, Thomas; Spahiu, Kastriot

2009-08-01

Release of long-lived radionuclides such as plutonium and caesium from spent nuclear fuel in deep geological repositories will depend mainly on the dissolution rate of the UO 2 fuel matrix. This dissolution rate will, in turn, depend on the redox conditions at the fuel surface. Under oxidative conditions UO 2 will be oxidised to the 1000 times more soluble UO 2.67. This may occur in a repository as the reducing deep groundwater becomes locally oxidative at the fuel surface under the effect of α-radiolysis, the process by which α-particles emitted from the fuel split water molecules. On the other hand, the groundwater corrodes canister iron generating large amounts of hydrogen. The role of molecular hydrogen as reductant in a deep bedrock repository is questioned. Here we show evidence of a surface-catalysed reaction, taking place in the H 2-UO 2-H 2O system where molecular hydrogen is able to reduce oxidants originating from α-radiolysis. In our experiment the UO 2 surface remained stoichiometric proving that the expected oxidation of UO 2.00 to UO 2.67 due to radiolytic oxidants was absent. As a consequence, the dissolution of UO 2 stopped when equilibrium was reached between the solid phase and U 4+ species in the aqueous phase. The steady-state concentration of uranium in solution was determined to be 9 × 10 -12 M, about 30 times lower than previously reported for reducing conditions. Our findings show that fuel dissolution is suppressed by H 2. Consequently, radiotoxic nuclides in spent nuclear fuel will remain immobilised in the UO 2 matrix. A mechanism for the surface-catalysed reaction between molecular hydrogen and radiolytic oxidants is proposed.

Does the Fukushima NPP disaster affect the caesium activity of North Atlantic Ocean fish?

NASA Astrophysics Data System (ADS)

Kanisch, G.; Aust, M.-O.

2013-08-01

Fillet samples of marine fish collected from the East/West Greenland currents (GC) and from the Baltic Sea (BS) have been investigated by gamma-ray spectrometry within the regular German monitoring programme. In samples of the second half of 2011, 134Cs traces have been detected that are suggested to originate from the Fukushima fallout that was deposited in March/April 2011 over the northern North Atlantic and accumulated by fish. The radionuclide 134Cs (half-life 2 yr) was indeed detected with quite small activities at about 0.0036 Bq kg-1 w.w. Existing box models describing the transport of Cs within seawater boxes of the northeast Atlantic allowed for estimation of 134Cs contributions from other sources, i.e. from the Chernobyl fallout and from discharges by the two major European nuclear reprocessing plants; both were negligible around Greenland, while for the Chernobyl fallout a small 134Cs background contribution to BS fish was estimated. Model results confirmed the level of 134C measured in BS fish and showed its maximum to have occurred in winter 2011/2012 followed by a continuous decrease. It was also determined that 134Cs activity, but not that of 134Cs, showed a significant negative correlation with sampling depth (150-400 m) of GC fish; this strengthens our Fukushima fallout assumption. As a result, the Fukushima fallout in these sea areas only marginally enhanced (GC: 4%; BS: 0.1%) pre-Fukushima levels of individual dose rates received by human fish consumers; the addition was around 0.001 μSv following the consumption of 10 kg of fish per year, which is not expected to cause concern according to present guidelines for radiation protection.

Does the Fukushima NPP disaster affect the caesium activity of North Atlantic Ocean fish?

NASA Astrophysics Data System (ADS)

Kanisch, G.; Aust, M.-O.

2013-03-01

Fillet samples of marine fish collected from the East/West Greenland current (GC) and from the Baltic Sea (BS), have been investigated by gamma-ray spectrometry within the regular German monitoring program. In samples of the second half of 2011 134Cs traces have been detected, suggested to originate from the Fukushima fallout being deposited in March/April 2011 over the northern North Atlantic and accumulated by fish. The radionuclide 134Cs (half-live 2 yr) was indeed detected with quite small activities at about 0.0036 Bq kg-1 w.w. Existing box-models describing the transport of Cs within seawater boxes of the NE Atlantic allowed estimating that 134Cs contributions from other sources, i.e. from the Chernobyl fallout and from discharges by the two major European nuclear reprocessing plants, both were negligible around Greenland, while for the Chernobyl fallout a small 134Cs background contribution to BS fish was estimated. Model results confirmed the level of 134Cs measured in BS fish and showed its maximum to have occurred in winter 2011/2012 followed by a continuous decrease. It was also determined that 134Cs activity, but not that of 134Cs, showed a significant negative correlation with sampling depth (150-400 m) of GC fish; this strengthens our Fukushima fallout assumption. As a result, the Fukushima fallout in these sea areas only marginally enhanced (GC: 4%; BS: 0.1%) pre-Fukushima levels of individual dose rates received by human fish consumers; the addition was around 0.001 μSv following the consumption of 10 kg fish per year, which is not expected to cause concern according to present guidelines for radiation protection.

Purified human breast milk MUC1 and MUC4 inhibit human immunodeficiency virus.

PubMed

Mthembu, Yolanda; Lotz, Zoe; Tyler, Marilyn; de Beer, Corena; Rodrigues, Jeronimo; Schoeman, Leann; Mall, Anwar Suleman

2014-01-01

The HIV-AIDS pandemic is prevalent in sub-Saharan Africa. Breastfeeding is a risk factor, with transmission from mother to child being as high as 40%. To determine the antiviral activity of crude breast milk and its purified mucins MUC1 and MUC4 against HIV-1 in patients who were HIV positive compared to those who were not. Twenty-one human milk samples were taken from both groups. Breast milk mucins were purified by density-gradient ultracentrifugation in caesium chloride and analyzed by SDS-PAGE, Western blotting and amino acid content. The inhibition of the virus by crude milk and purified mucin was assayed by an in vitro HIV-1 p24 assay. SDS-PAGE for purified mucin showed several high-molecular-weight bands for the HIV-negative group and prominently stained single bands on the stacking gel with faintly periodic acid Schiff-positive glycoprotein bands observed in some cases in the running gel for the HIV-positive mucins. Western blot analysis identified the mucins in both groups to be MUC1 and MUC4. Both mucins showed more intensity on Western blotting for the HIV-positive group. There was no difference in the content of serine, threonine and proline of purified mucins for both groups. HIV-1 was not inhibited by crude breast milk from normal (13/14 samples) and infected individuals (19/19 samples). Fifteen of 20 and 16/18 samples of purified mucin from the uninfected and HIV-positive groups, respectively, inhibited the virus. Crude breast milk does not inhibit HIV-1, whilst purified mucins do in an in vitro assay. © 2014 S. Karger AG, Basel.

Demand driven salt clean-up in a molten salt fast reactor – Defining a priority list

PubMed Central

Litskevich, D.; Gregg, R.; Mount, A. R.

2018-01-01

The PUREX technology based on aqueous processes is currently the leading reprocessing technology in nuclear energy systems. It seems to be the most developed and established process for light water reactor fuel and the use of solid fuel. However, demand driven development of the nuclear system opens the way to liquid fuelled reactors, and disruptive technology development through the application of an integrated fuel cycle with a direct link to reactor operation. The possibilities of this new concept for innovative reprocessing technology development are analysed, the boundary conditions are discussed, and the economic as well as the neutron physical optimization parameters of the process are elucidated. Reactor physical knowledge of the influence of different elements on the neutron economy of the reactor is required. Using an innovative study approach, an element priority list for the salt clean-up is developed, which indicates that separation of Neodymium and Caesium is desirable, as they contribute almost 50% to the loss of criticality. Separating Zirconium and Samarium in addition from the fuel salt would remove nearly 80% of the loss of criticality due to fission products. The theoretical study is followed by a qualitative discussion of the different, demand driven optimization strategies which could satisfy the conflicting interests of sustainable reactor operation, efficient chemical processing for the salt clean-up, and the related economic as well as chemical engineering consequences. A new, innovative approach of balancing the throughput through salt processing based on a low number of separation process steps is developed. Next steps for the development of an economically viable salt clean-up process are identified. PMID:29494604

Hydrometallurgical recovery of metals: Ce, La, Co, Fe, Mn, Ni and Zn from the stream of used Ni-MH cells.

PubMed

Sobianowska-Turek, Agnieszka

2018-04-11

The utilization of the stream of waste secondary nickel-metal hydride (Ni-MH) and lithium-ion (Li-ion) cells, representing annually about 33% of all consumer batteries and accumulators placed on the Polish market, will soon become a big challenge for both legislators and plants dealing with the recycling of this type of hazardous waste. It is due to the fact that no company in Poland operating on the market has a complete technology for the processing of a full stream of waste chemical energy sources produced in this country. Until now, the most commonly used techniques of processing this type of waste were pyrometallurgical process. In this paper, the quantitative and qualitative characteristics of the stream of waste batteries and accumulators collected at separate collection points are presented. The results of metal recovery: caesium, lanthanum, cobalt, iron, manganese, nickel and zinc from the stream of waste Ni-MH cells, type R6 (AA), using hydrometallurgical methods are also offered. The paper demonstrates that one-stage leaching at an initial temperature of 25.0 °C, with 3 M H 2 SO 4 and at the solid to liquid ratio of s/l = 1/10, within 75 min, at a mixing speed of 500 rpm and in a strongly acidic environment should be adopted as optimal parameters for acid leaching of the paramagnetic fraction created after mechanical machining of Ni-MH battery, for which the leaching rates of individual metals were as follows: Ce - 97.7%, La - 88.7%, Co - 79.4%, Fe - 68.5%, Mn - 91.9%, Ni - 66.2% and Zn - 100%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Investigations on Cs-free alternatives for negative ion formation in a low pressure hydrogen discharge at ion source relevant parameters

NASA Astrophysics Data System (ADS)

Kurutz, U.; Friedl, R.; Fantz, U.

2017-07-01

Caesium (Cs) is applied in high power negative hydrogen ion sources to reduce a converter surface’s work function and thus enabling an efficient negative ion surface formation. Inherent drawbacks with the usage of this reactive alkali metal motivate the search for Cs-free alternative materials for neutral beam injection systems in fusion research. In view of a future DEMOnstration power plant, a suitable material should provide a high negative ion formation efficiency and comply with the RAMI issues of the system: reliability, availability, maintainability, inspectability. Promising candidates, like low work function materials (molybdenum doped with lanthanum (MoLa) and LaB6), as well as different non-doped and boron-doped diamond samples were investigated in this context at identical and ion source relevant parameters at the laboratory experiment HOMER. Negative ion densities were measured above the samples by means of laser photodetachment and compared with two reference cases: pure negative ion volume formation with negative ion densities of about 1× {10}15 {{{m}}}-3 and the effect of H- surface production using an in situ caesiated stainless steel sample which yields 2.5 times higher densities. Compared to pure volume production, none of the diamond samples did exhibit a measurable increase in H- densities, while showing clear indications of plasma-induced erosion. In contrast, both MoLa and LaB6 produced systematically higher densities (MoLa: ×1.60 LaB6: ×1.43). The difference to caesiation can be attributed to the higher work functions of MoLa and LaB6 which are expected to be about 3 eV for both compared to 2.1 eV of a caesiated surface.

Purification of adenoviral vectors by combined anion exchange and gel filtration chromatography.

PubMed

Eglon, Marc N; Duffy, Aoife M; O'Brien, Timothy; Strappe, Padraig M

2009-11-01

Adenoviral vectors are used extensively in human gene therapy trials and in vaccine development. Large-scale GMP production requires a downstream purification process, and liquid chromatography is emerging as the most powerful mode of purification, enabling the production of vectors at a clinically relevant scale and quality. The present study describes the development of a two-step high-performance liquid chromatography (HPLC) process combining anion exchange (AIEX) and gel filtration (GF) in comparison with the caesium chloride density gradient method. HEK-293 cells were cultured in ten-layer CellStacks() and infected with 10 pfu/cell of adenoviral vector expressing green fluorescent protein (Ad5-GFP). Cell-bound virus was harvested and benzonase added to digest DNA, crude lysate was clarified by centrifugation and filtration prior to HPLC. Chromatography fractions were added to HEK-293 cells and GFP expression measured using a fluorescent plate reader. Using AIEX then GF resulted in an adenoviral vector with purity comparable to Ad5-GFP purified by CsCl, whereas the reverse process (GF-AIEX) showed a reduced purity by electrophoresis and required further buffer exchange of the product. The optimal process (AIEX-GF) resulted in a vector yield of 2.3 x 10(7) pfu/cm(2) of cell culture harvested compared to 3.3 x 10(7) pfu/cm(2) for CsCl. The process recovery for the HPLC process was 36% compared to 27.5% for CsCl and total virion to infectious particle ratios of 18 and 11, respectively, were measured. We present a simple two-step chromatography process that is capable of producing high-quality adenovirus at a titre suitable for scale-up and clinical translation.

Atomic weights of the elements 2013 (IUPAC Technical Report)

USGS Publications Warehouse

Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna; Loss, Robert D.; Walczyk, Thomas; Prohaska, Thomas

2016-01-01

The biennial review of atomic-weight determinations and other cognate data has resulted in changes for the standard atomic weights of 19 elements. The standard atomic weights of four elements have been revised based on recent determinations of isotopic abundances in natural terrestrial materials:cadmium to 112.414(4) from 112.411(8),molybdenum to 95.95(1) from 95.96(2),selenium to 78.971(8) from 78.96(3), andthorium to 232.0377(4) from 232.038 06(2). The Commission on Isotopic Abundances and Atomic Weights (ciaaw.org) also revised the standard atomic weights of fifteen elements based on the 2012 Atomic Mass Evaluation:aluminium (aluminum) to 26.981 5385(7) from 26.981 5386(8),arsenic to 74.921 595(6) from 74.921 60(2),beryllium to 9.012 1831(5) from 9.012 182(3),caesium (cesium) to 132.905 451 96(6) from 132.905 4519(2),cobalt to 58.933 194(4) from 58.933 195(5),fluorine to 18.998 403 163(6) from 18.998 4032(5),gold to 196.966 569(5) from 196.966 569(4),holmium to 164.930 33(2) from 164.930 32(2),manganese to 54.938 044(3) from 54.938 045(5),niobium to 92.906 37(2) from 92.906 38(2),phosphorus to 30.973 761 998(5) from 30.973 762(2),praseodymium to 140.907 66(2) from 140.907 65(2),scandium to 44.955 908(5) from 44.955 912(6),thulium to 168.934 22(2) from 168.934 21(2), andyttrium to 88.905 84(2) from 88.905 85(2). The Commission also recommends the standard value for the natural terrestrial uranium isotope ratio, N(238U)/N(235U)=137.8(1).

Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

PubMed Central

Sutton, Rebecca; Sposito, Garrison

2002-01-01

Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers) provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

Bioindicator responses and performance of plant species along a vehicular pollution gradient in western Himalaya.

PubMed

Kashyap, Rachit; Sharma, Rohit; Uniyal, Sanjay Kr

2018-04-21

Loss of green cover, and increasing pollution is a prime global concern. The problem calls for screening of pollution-tolerant tree species that can be integrated into plantation drives. Recognizing this, the study analyzed bio-indicator responses and performance of commonly occurring plant species along a pollution gradient in western Himalaya. Based on distance from the road, three sites viz., highly polluted (HP), moderately polluted (MP), and least polluted (LP), were identified. From these sites, leaves of commonly occurring 26 tree species were collected and analyzed for dust accumulation, total chlorophyll, relative water content (RWC), ascorbic acid, and pH using standard protocols. Later, assessment of Air Pollution Tolerance Index (APTI) and Anticipated Performance Indices (API) was carried out. The results revealed variations in biochemical characteristics. The pH, RWC, and total chlorophyll increased with decreasing pollution while ascorbic acid increased with increasing pollution. Dust capturing potential of Ficus carica (1.191 mg/m 2 ) and Toona ciliata (0.820 mg/m 2 ) was relatively higher. Based on the results of APTI, Grevillea robusta was classified as tolerant. It scored significantly higher values (21.06, 21.19, and 19.61 in LP, MP, and HP sites, respectively). Quercus floribunda, G. robusta (68.75% each), Juglans regia (68.7%), and T. ciliata (62.50%) were good performers in HP sites. Acer caesium, Betula utilis, and Morus alba that had low API scores (43.75%) were predicted as poor performers. Thus, G. robusta, Q. floribunda, J. regia, T. ciliata, and F. carica were evaluated as best performers. They could be integrated into plantations drives for environmental management.

Xenon-133 and caesium-137 releases into the atmosphere from the Fukushima Dai-ichi nuclear power plant: determination of the source term, atmospheric dispersion, and deposition

NASA Astrophysics Data System (ADS)

Stohl, A.; Seibert, P.; Wotawa, G.; Arnold, D.; Burkhart, J. F.; Eckhardt, S.; Tapia, C.; Vargas, A.; Yasunari, T. J.

2012-03-01

On 11 March 2011, an earthquake occurred about 130 km off the Pacific coast of Japan's main island Honshu, followed by a large tsunami. The resulting loss of electric power at the Fukushima Dai-ichi nuclear power plant developed into a disaster causing massive release of radioactivity into the atmosphere. In this study, we determine the emissions into the atmosphere of two isotopes, the noble gas xenon-133 (133Xe) and the aerosol-bound caesium-137 (137Cs), which have very different release characteristics as well as behavior in the atmosphere. To determine radionuclide emissions as a function of height and time until 20 April, we made a first guess of release rates based on fuel inventories and documented accident events at the site. This first guess was subsequently improved by inverse modeling, which combined it with the results of an atmospheric transport model, FLEXPART, and measurement data from several dozen stations in Japan, North America and other regions. We used both atmospheric activity concentration measurements as well as, for 137Cs, measurements of bulk deposition. Regarding 133Xe, we find a total release of 15.3 (uncertainty range 12.2-18.3) EBq, which is more than twice as high as the total release from Chernobyl and likely the largest radioactive noble gas release in history. The entire noble gas inventory of reactor units 1-3 was set free into the atmosphere between 11 and 15 March 2011. In fact, our release estimate is higher than the entire estimated 133Xe inventory of the Fukushima Dai-ichi nuclear power plant, which we explain with the decay of iodine-133 (half-life of 20.8 h) into 133Xe. There is strong evidence that the 133Xe release started before the first active venting was made, possibly indicating structural damage to reactor components and/or leaks due to overpressure which would have allowed early release of noble gases. For 137Cs, the inversion results give a total emission of 36.6 (20.1-53.1) PBq, or about 43% of the estimated Chernobyl emission. Our results indicate that 137Cs emissions peaked on 14-15 March but were generally high from 12 until 19 March, when they suddenly dropped by orders of magnitude at the time when spraying of water on the spent-fuel pool of unit 4 started. This indicates that emissions may not have originated only from the damaged reactor cores, but also from the spent-fuel pool of unit 4. This would also confirm that the spraying was an effective countermeasure. We explore the main dispersion and deposition patterns of the radioactive cloud, both regionally for Japan as well as for the entire Northern Hemisphere. While at first sight it seemed fortunate that westerly winds prevailed most of the time during the accident, a different picture emerges from our detailed analysis. Exactly during and following the period of the strongest 137Cs emissions on 14 and 15 March as well as after another period with strong emissions on 19 March, the radioactive plume was advected over Eastern Honshu Island, where precipitation deposited a large fraction of 137Cs on land surfaces. Radioactive clouds reached North America on 15 March and Europe on 22 March. By middle of April, 133Xe was fairly uniformly distributed in the middle latitudes of the entire Northern Hemisphere and was for the first time also measured in the Southern Hemisphere (Darwin station, Australia). In general, simulated and observed concentrations of 133Xe and 137Cs both at Japanese as well as at remote sites were in good quantitative agreement. Altogether, we estimate that 6.4 PBq of 137Cs, or 18% of the total fallout until 20 April, were deposited over Japanese land areas, while most of the rest fell over the North Pacific Ocean. Only 0.7 PBq, or 1.9% of the total fallout were deposited on land areas other than Japan.

Formation of titanium phosphate composites during phosphoric acid decomposition of natural sphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maslova, Marina V.; Rusanova, Daniela; Naydenov, Valeri

2008-12-15

Decomposition of mineral sphene, CaTiOSiO{sub 4}, by H{sub 3}PO{sub 4} is investigated in detail. During the dissolution process, simultaneous calcium leaching and formation of titanium phosphate (TiP) take place. The main product of decomposition is a solid titanium phosphate-silica composite. The XRD, solid-sate NMR, IR, TGA, SEM and BET data were used to identify and characterize the composite as a mixture of crystalline Ti(HPO{sub 4}){sub 2}.H{sub 2}O and silica. When 80% phosphoric acid is used the decomposition degree is higher than 98% and calcium is completely transferred into the liquid phase. Formation of Ti(HPO{sub 4}){sub 2}.H{sub 2}O proceeds via formationmore » of meta-stable titanium phosphate phases, Ti(H{sub 2}PO{sub 4})(PO{sub 4}).2H{sub 2}O and Ti(H{sub 2}PO{sub 4})(PO{sub 4}). The sorption affinities of TiP composites were examined in relation to caesium and strontium ions. A decrease of H{sub 3}PO{sub 4} concentration leads to formation of composites with greater sorption properties. The maximum sorption capacity of TiP is observed when 60% H{sub 3}PO{sub 4} is used in sphene decomposition. The work demonstrates a valuable option within the Ti(HPO{sub 4}){sub 2}.H{sub 2}O-SiO{sub 2} composite synthesis scheme, to use phosphoric acid flows for isolation of CaHPO{sub 4}.2H{sub 2}O fertilizer. - Graphical abstract: A new synthesis scheme for preparation of composite titanium phosphate (TiP) ion-exchangers upon one-stage decomposition process of natural sphene with phosphoric acid is presented. Syntheses of {alpha}-TiP-silica composites proceed via formation of meta-stable titanium phosphate phases. The concentration of H{sub 3}PO{sub 4} determines the porosity of final products and their sorption affinities.« less

The in vivo performance of a novel thermal accelerant agent used for augmentation of microwave energy delivery within biologic tissues during image-guided thermal ablation: a porcine study.

PubMed

Park, William Keun Chan; Maxwell, Aaron Wilhelm Palmer; Frank, Victoria Elizabeth; Primmer, Michael Patrick; Paul, Jarod Brian; Collins, Scott Andrew; Lombardo, Kara Anne; Lu, Shaolei; Borjeson, Tiffany Marie; Baird, Grayson Luderman; Dupuy, Damian Edward

2018-02-01

To investigate the effects of a novel caesium-based thermal accelerant (TA) agent on ablation zone volumes following in vivo microwave ablation of porcine liver and skeletal muscle, and to correlate the effects of TA with target organ perfusion. This prospective study was performed following institutional animal care and use committee approval. Microwave ablation was performed in liver and resting skeletal muscle in eight Sus scrofa domesticus swine following administration of TA at concentrations of 0 mg/mL (control), 100 mg/mL and 250 mg/mL. Treated tissues were explanted and stained with triphenyltetrazolium chloride (TTC) for quantification of ablation zone volumes, which were compared between TA and control conditions. Hematoxylin and eosin (H&E) staining was also performed for histologic analysis. General mixed modelling with a log-normal distribution was used for all quantitative comparisons (p = 0.05). A total of 28 ablations were performed in the liver and 18 in the skeletal muscle. The use of TA significantly increased ablation zone volumes in a dose-dependent manner in both the porcine muscle and liver (p < 0.01). Both the absolute mean ablation zone volume and percentage increase in ablation zone volume were greater in the resting skeletal muscle than in the liver. In one swine, a qualitative mitigation of heat sink effects was observed by TTC and H&E staining. Non-lethal polymorphic ventricular tachycardia was identified in one swine, treated with intravenous amiodarone. The use of a novel TA agent significantly increased mean ablation zone volumes following microwave ablation using a porcine model. The relationship between TA administration and ablation size was dose-dependent and inversely proportional to the degree of target organ perfusion, and a qualitative reduction in heat-sink effects was observed.

SU-F-P-24: Radiological Disperse Device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alam, R

Purpose: We are now living in a society of constant fear of terrorism. This topic is pertaining to give a general knowledge of what is a radiological dispersion device or RDD and in case of its detonation, what are the options open to public for a safe action in terms of reducing the exposure and knowing the proper steps. These RDD are also called dirty bombs. Methods: Compared to nuclear weapons, dirty bombs are easy to make. In order for a terrorist organization to construct and detonate a dirty bomb, it must acquire radioactive material by stealing it or buyingmore » it through legal or illegal channels. Possible RDD material could come from the millions of radioactive sources used in the industry, for medical purposes and in academic applications mainly for researches. These are, americium-{sup 241}, californium-{sup 252}, caesium-{sup 137}, cobalt-{sup 60}, iridium-{sup 192}, plutonium-{sup 238}, polonium-{sup 210}, radium-{sup 226} and strontium-{sup 90}. Results: Prompt detection of the type of radioactive material used will greatly assist advising people on the protective measures, like sheltering in place, or quickly leaving the immediate area. The effects of radiation are determined by:°the amount of radiation absorbed by body°the type of radiation °the distance from the radiation to an individual°the means of exposure absorbed by the skin, inhaled, or ingested; and length of time exposed. Conclusion: In any facility it is now much more important to keep a log list of all radioactive materials in use. In case there is a dirty bomb explosion, the chaos and economic cost could be enormous. The economic cost for the evaluation of the contamination, survey of people and surroundings and the after treatment, decontamination cost and effort will be a big challenge in any country. So awareness and preparation is the start to face this new type of challenge.« less

Investigations of antioxidant-mediated protection and mitigation of radiation-induced DNA damage and lipid peroxidation in murine skin.

PubMed

Jelveh, Salomeh; Kaspler, Pavel; Bhogal, Nirmal; Mahmood, Javed; Lindsay, Patricia E; Okunieff, Paul; Doctrow, Susan R; Bristow, Robert G; Hill, Richard P

2013-08-01

Radioprotection and mitigation effects of the antioxidants, Eukarion (EUK)-207, curcumin, and the curcumin analogs D12 and D68, on radiation-induced DNA damage or lipid peroxidation in murine skin were investigated. These antioxidants were studied because they have been previously reported to protect or mitigate against radiation-induced skin reactions. DNA damage was assessed using two different assays. A cytokinesis-blocked micronucleus (MN) assay was performed on primary skin fibroblasts harvested from the skin of C3H/HeJ male mice 1 day, 1 week and 4 weeks after 5 Gy or 10 Gy irradiation. Local skin or whole body irradiation (100 kVp X-rays or caesium (Cs)-137 γ-rays respectively) was performed. DNA damage was further quantified in keratinocytes by immunofluorescence staining of γ-histone 2AX (γ-H2AX) foci in formalin-fixed skin harvested 1 hour or 1 day post-whole body irradiation. Radiation-induced lipid peroxidation in the skin was investigated at the same time points as the MN assay by measuring malondialdehyde (MDA) with a Thiobarbituric acid reactive substances (TBARS) assay. None of the studied antioxidants showed significant mitigation of skin DNA damage induced by local irradiation. However, when EUK-207 or curcumin were delivered before irradiation they provided some protection against DNA damage. In contrast, all the studied antioxidants demonstrated significant mitigating and protecting effects on radiation-induced lipid peroxidation at one or more of the three time points after local skin irradiation. Our results show no evidence for mitigation of DNA damage by the antioxidants studied in contrast to mitigation of lipid peroxidation. Since these agents have been reported to mitigate skin reactions following irradiation, the data suggest that changes in lipid peroxidation levels in skin may reflect developing skin reactions better than residual post-irradiation DNA damage in skin cells. Further direct comparison studies are required to confirm this inference from the data.

Simultaneous quantification of iodine and high valent metals via ICP-MS under acidic conditions in complex matrices.

PubMed

Brix, Kristina; Hein, Christina; Sander, Jonas Michael; Kautenburger, Ralf

2017-05-15

The determination of iodine as a main fission product (especially the isotopes I-129 and I-131) of stored HLW in a disposal beside its distribution as a natural ingredient of many different products like milk, food and seawater is a matter of particular interest. The simultaneous ICP-MS determination of iodine as iodide together with other elements (especially higher valent metal ions) relevant for HLW is analytically very problematic. A reliable ICP-MS quantification of iodide must be performed at neutral or alkaline conditions in contrast to the analysis of metal ions which are determined in acidic pH ranges. Herein, we present a method to solve this problem by changing the iodine speciation resulting in an ICP-MS determination of iodide as iodate. The oxidation from iodide to iodate with sodium hypochlorite at room temperature is a fast and convenient method with flexible reaction time, from one hour up to three days, thus eliminating the disadvantages of quantifying iodine species via ICP-MS. In the analysed concentration range of iodine (0.1-100µgL -1 ) we obtain likely quantitative recovery rates for iodine between 91% and 102% as well as relatively low RSD values (0.3-4.0%). As an additional result, it is possible to measure different other element species in parallel together with the generated iodate, even high valent metals (europium and uranium beside caesium) at recovery rates in the same order of magnitude (93-104%). In addition, the oxidation process operates above pH 7 thus offering a wide pH range for sample preparation. Even analytes in complex matrices, like 5M saline (NaCl) solution or artificial cement pore water (ACW) can be quantified with this robust sample preparation method. Copyright © 2017 Elsevier B.V. All rights reserved.

The role of livestock-poached pasture as a sediment source

NASA Astrophysics Data System (ADS)

Greenwood, Philip; Walling, Desmond; Quine, Timothy

2015-04-01

Historically, the occurrence of sediment-laden runoff has almost exclusively been associated with cultivated hillslopes and particularly with arable land. This association was commonly accompanied by the presumption that, in comparison with cultivated slopes, erosion from intensively-managed lowland pasture was relatively low. Recent developments in sediment source tracing and fingerprinting techniques have, however, challenged these assumptions by demonstrating that soil loss from grasslands may be greater than previously assumed. In attempting to identify potential source areas within grassland environments, attention has frequently focused on areas of livestock poaching where herd animals tend to congregate. However, the role of poached grassland as a sediment-source remains uncertain. Reasons include the difficulties associated with accurately documenting the movement or redistribution of small quantities of fine sediment over relevant spatial and temporal scales. Motivated by an urgent need for such information, this communication presents preliminary results from a tracing study aimed at measuring sediment redistribution within areas of poached pasture over short (i.e. event-based) timescales using the artificial radionuclides, caesium-134 (134Cs) and cobalt-60 (60Co). The approach involved labelling six small areas (0.2 * 0.2 m) of poached soil, each with a contrasting gradient, with either 134Cs or 60Co, and then measuring changes in the radiometric inventory at predetermined points before and after periods of rainfall. Each labelled area of poached pasture was measured on three separate occasions over a 65 day period. At the end of the monitoring phase, the mean net soil redistribution depth (mm) was negative for all plots, with values ranging from -6.8 mm to -15.2 mm. This is interpreted as evidence of the removal, or erosion, of surface material. The findings indicate that areas of livestock-poached pasture can act as significant sediment sources. These findings are discussed with regard to the potential contribution of poaching to the off-site transfer of fine-sediment from affected grasslands, and to the implications for the water quality of receiving streams.

‘… a metal conducts and a non-metal doesn't’

PubMed Central

Edwards, P. P.; Lodge, M. T. J.; Hensel, F.; Redmer, R.

2010-01-01

In a letter to one of the authors, Sir Nevill Mott, then in his tenth decade, highlighted the fact that the statement ‘… a metal conducts, and a non-metal doesn’t’ can be true only at the absolute zero of temperature, T=0 K. But, of course, experimental studies of metals, non-metals and, indeed, the electronic and thermodynamic transition between these canonical states of matter must always occur above T=0 K, and, in many important cases, for temperatures far above the absolute zero. Here, we review the issues—theoretical and experimental—attendant on studies of the metal to non-metal transition in doped semiconductors at temperatures close to absolute zero (T=0.03 K) and fluid chemical elements at temperatures far above absolute zero (T>1000 K). We attempt to illustrate Mott’s insights for delving into such complex phenomena and experimental systems, finding intuitively the dominant features of the science, and developing a coherent picture of the different competing electronic processes. A particular emphasis is placed on the idea of a ‘Mott metal to non-metal transition’ in the nominally metallic chemical elements rubidium, caesium and mercury, and the converse metallization transition in the nominally non-metal elements hydrogen and oxygen. We also review major innovations by D. A. Goldhammer (Goldhammer 1913 Dispersion und absorption des lichtes) and K. F. Herzfeld (Herzfeld 1927 Phys. Rev. 29, 701–705. (doi:10.1103/PhysRev.29.701)) in a pre-quantum theory description of the metal–non-metal transition, which emphasize the pivotal role of atomic properties in dictating the metallic or non-metallic status of the chemical elements of the periodic table under ambient and extreme conditions; a link with Pauling’s ‘metallic orbital’ is also established here. PMID:20123742

Total cancer incidence in relation to 137Cs fallout in the most contaminated counties in Sweden after the Chernobyl nuclear power plant accident: a register-based study.

PubMed

Alinaghizadeh, Hassan; Wålinder, Robert; Vingård, Eva; Tondel, Martin

2016-12-20

To determine the total cancer incidence in relation to a 5-year exposure to caesium-137 ( 137 Cs) from the 1986 Chernobyl nuclear power plant accident. A closed cohort was defined as all individuals living in the three most contaminated counties in mid-Sweden in 1986. Fallout of 137 Cs was retrieved as a digital map from the Geological Survey of Sweden, demographic data from Statistics Sweden, and cancer diagnosis from the National Board of Health and Welfare. Individuals were assigned an annual 137 Cs exposure based on their place of residence (1986-1990), from which 5-year cumulative 137 Cs exposures were calculated, accounting for the physical decay of 137 Cs and changing residencies. HRs were adjusted for age, sex, rural/non-rural residence and pre-Chernobyl total cancer incidence. The 734 537 people identified were categorised by exposure: the first quartile was low exposure (0.0-45.4 kBq/m 2 ), the second and third quartiles were intermediate exposure (45.41-118.8 kBq/m 2 ), and the fourth quartile was the highest exposure (118.81-564.71 kBq/m 2 ). Between 1991 and 2010, 82 495 cancer cases were registered in the 3 counties. Adjusted HRs (95% CI) were 1.03 (1.01 to 1.05) for intermediate exposure and 1.05 (1.03 to 1.07) for the highest exposure compared to the reference exposure. We found a small overall exposure-response pattern of the total cancer incidence related to 137 Cs after adjustment for age, sex, rural residence and pre-Chernobyl cancer incidence. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Effective Half-Life of Caesium-137 in Various Environmental Media at the Savannah River Site

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paller, M. H.; Jannik, G. T.; Baker, R. A.

2014-05-01

During the operational history of the Savannah River Site (SRS), many different radionuclides have been released from site facilities into the SRS environment. However, only a relatively small number of pathways, most importantly 137Cs in fish and deer, have contributed significantly to doses and risks to the public. The “effective” half-lives (T e) of 137Cs (which include both physical decay and environmental dispersion) in Savannah River floodplain soil and vegetation and in fish and white-tailed deer from the SRS were estimated using long-term monitoring data. For 1974–2011, the T es of 137Cs in Savannah River floodplain soil and vegetation weremore » 17.0 years (95% CI = 14.2–19.9) and 13.4 years (95% CI = 10.8–16.0), respectively. These T es were greater than in a previous study that used data collected only through 2005 as a likely result of changes in the flood regime of the Savannah River. Field analyses of 137Cs concentrations in deer collected during yearly controlled hunts at the SRS indicated an overall T e of 15.9 years (95% CI = 12.3–19.6) for 1965–2011; however, the T e for 1990–2011 was significantly shorter (11.8 years, 95% CI = 4.8–18.8) due to an increase in the rate of 137Cs removal. The shortest T es were for fish in SRS streams and the Savannah River (3.5–9.0 years), where dilution and dispersal resulted in rapid 137Cs removal. Long-term data show that T es are significantly shorter than the physical half-life of 137Cs in the SRS environment but that they can change over time. Therefore, it is desirable have a long period of record for calculating Tes and risky to extrapolate T es beyond this period unless the processes governing 137Cs removal are clearly understood.« less

Using plot experiments to test the validity of mass balance models employed to estimate soil redistribution rates from 137Cs and 210Pb(ex) measurements.

PubMed

Porto, Paolo; Walling, Des E

2012-10-01

Information on rates of soil loss from agricultural land is a key requirement for assessing both on-site soil degradation and potential off-site sediment problems. Many models and prediction procedures have been developed to estimate rates of soil loss and soil redistribution as a function of the local topography, hydrometeorology, soil type and land management, but empirical data remain essential for validating and calibrating such models and prediction procedures. Direct measurements using erosion plots are, however, costly and the results obtained relate to a small enclosed area, which may not be representative of the wider landscape. In recent years, the use of fallout radionuclides and more particularly caesium-137 ((137)Cs) and excess lead-210 ((210)Pb(ex)) has been shown to provide a very effective means of documenting rates of soil loss and soil and sediment redistribution in the landscape. Several of the assumptions associated with the theoretical conversion models used with such measurements remain essentially unvalidated. This contribution describes the results of a measurement programme involving five experimental plots located in southern Italy, aimed at validating several of the basic assumptions commonly associated with the use of mass balance models for estimating rates of soil redistribution on cultivated land from (137)Cs and (210)Pb(ex) measurements. Overall, the results confirm the general validity of these assumptions and the importance of taking account of the fate of fresh fallout. However, further work is required to validate the conversion models employed in using fallout radionuclide measurements to document soil redistribution in the landscape and this could usefully direct attention to different environments and to the validation of the final estimates of soil redistribution rate as well as the assumptions of the models employed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Gamma greenhouse: A chronic facility for crops improvement and agrobiotechnology

NASA Astrophysics Data System (ADS)

Azhar, M.; Ahsanulkhaliqin, A. W.

2014-02-01

Gamma irradiation is one of the most common procedures in plant mutagenesis and agrobiotechnology activities. The procedures consist of chronic and acute gamma radiation. Generally, 60Co and 137Cs are gamma radiation sources for radiation processing with relatively high energy (half-life 5.27 years for 60Co and 30.1 years for 137Cs). The energy associated with gamma radiation is high enough to break the molecular bonds and ionize atoms without affecting structure of the atomic nucleus (avoiding induction of radioactivity). The Gamma Green House (GGH) is the only chronic irradiation facility in Malaysia, located at Malaysian Nuclear Agency (Nuclear Malaysia). GGH is used for induction of mutation in plants and other biological samples at low dose radiation over period of time depending on the nature and sensitivity of the plant species. The GGH consist of circular green house with 30 meters radius, control room and irradiator with interlock system. The irradiator produces low dose gamma radiation derived from Caesium-137 radioactive source. The biological samples can be exposed to low dose radiation in days, weeks, months or years. The current irradiation rate for GGH is 2.67 Gy/hr at 1 meter from the source. Chronic gamma irradiation produces a wider mutation spectrum and useful for minimizing radiation damages towards obtaining new improved traits for research and commercial values. The prospect of the gamma greenhouse is its uses in research, educations and services on induced mutation techniques for the improvement of plant varieties and microbes. In generating awareness and attract users to the facility, Nuclear Malaysia provides wide range of irradiation services for plant species and mutagenesis consultancies to academicians, students scientists, and plant breeders, from local universities, other research institutes, and growers. Charges for irradiation and consultancy services are at nominal rates. The utilization activities of the gamma greenhouse mainly cover Research and Development, Research Collaboration, Exchange of Information, Irradiation Services, Training Programs, Education, Exchange of Scientists and Seminars/ Conferences.

New Detector Developments for Future UV Space Missions

NASA Astrophysics Data System (ADS)

Werner, Klaus; Kappelmann, Norbert

Ultraviolet (UV) astronomy is facing “dark ages”: After the shutdown of the Hubble Space Tele-scope only the WSO/UV mission will be operable in the UV wavelength region with efficient instruments. Improved optics and detectors are necessary for future successor missions to tackle new scientific goals. This drives our development of microchannel plate (MCP) UV-detectors with high quantum efficiency, high spatial resolution and low-power readout electronics. To enhance the quantum efficiency and the lifetime of the MCP detectors we are developing new cathodes and new anodes for these detectors. To achieve high quantum efficiency, we will use caesium-activated gallium nitride as semitransparent photocathodes with a much higher efficiency than default CsI/CsTe cathodes in this wavelength range. The new anodes will be cross-strip anodes with 64 horizontal and 64 vertical electrodes. This type of anode requires a lower gain and leads to an increased lifetime of the detector, compared to MCP detectors with other anode types. The heart of the new developed front-end-electronic for such type of anode is the so called “BEETLE chip”, which was designed by the MPI für Kernphysik Heidelberg for the LHCb ex-periment at CERN. This chip provides 128 input channels with charge-sensitive preamplifiers and shapers. Our design of the complete front-end readout electronics enables a total power con-sumption of less than 10 W. The MCP detector is intrinsically solar blind, single photon counting and has a very low read-out noise. To qualify this new type of detectors we are presently planning to build a small UV telescope for the usage on the German Technology Experimental Carrier (TET). Furthermore we are involved in the new German initiative for a Public Telescope, a space telescope equipped with an 80 cm mirror. One of the main instruments will be a high-resolution UV-Echelle Spectrograph that will be built by the University of Tübingen. The launch of this mission is scheduled for 2017.

Modelling of caesium dynamics in the negative ion sources at BATMAN and ELISE

NASA Astrophysics Data System (ADS)

Mimo, A.; Wimmer, C.; Wünderlich, D.; Fantz, U.

2017-08-01

The knowledge of Cs dynamics in negative hydrogen ion sources is a primary issue to achieve the ITER requirements for the Neutral Beam Injection (NBI) systems, i.e. one hour operation with an accelerated ion current of 40 A of D- and a ratio between negative ions and co-extracted electrons below one. Production of negative ions is mostly achieved by conversion of hydrogen/deuterium atoms on a converter surface, which is caesiated in order to reduce the work function and increase the conversion efficiency. The understanding of the Cs transport and redistribution mechanism inside the source is necessary for the achievement of high performances. Cs dynamics was therefore investigated by means of numerical simulations performed with the Monte Carlo transport code CsFlow3D. Simulations of the prototype source (1/8 of the ITER NBI source size) have shown that the plasma distribution inside the source has the major effect on Cs dynamics during the pulse: asymmetry of the plasma parameters leads to asymmetry in Cs distribution in front of the plasma grid. The simulated time traces and the general simulation results are in agreement with the experimental measurements. Simulations performed for the ELISE testbed (half of the ITER NBI source size) have shown an effect of the vacuum phase time on the amount and stability of Cs during the pulse. The sputtering of Cs due to back-streaming ions was reproduced by the simulations and it is in agreement with the experimental observation: this can become a critical issue during long pulses, especially in case of continuous extraction as foreseen for ITER. These results and the acquired knowledge of Cs dynamics will be useful to have a better management of Cs and thus to reduce its consumption, in the direction of the demonstration fusion power plant DEMO.

Aerial and Geophysical Archaeological Reconnaissance At Yangling, The Mausoleum of Emperor Jingdi In The Han Dynasty, China

NASA Astrophysics Data System (ADS)

Luo, Xizhe; Ye, Xinshi; Fassbinder, J. W. E.; Becker, H.

In 1998-2000, Shaanxi Province Conservation Bureau for Historical Monuments con- ducted an archaeology prospection research project at Yangling, Shaanxi province, China. Yangling, the mausoleum of Emperor Jingdi, is located about 20 kilometres northwest of the city of Xi'an. His mausoleum was constructed in the shape of a four- sided dipper or pyramid 31m high and 170m long each side, surrounded by a square wall of 401m along each side. Today the vestiges of the eastern, western and south- ern remains of the watchtowers previously on either side of gate can be clearly seen. Yangling took a long time to build and had the richest funeral objects. The Empress Wang died in 126 B.C. and also buried at Yangling to the northeastern side of Jingdi's tomb. The city of Yangling County was purposely built to the east of mausoleum. The officials, the rich and noble lived in the town, numbering over 100,000. Two groups of satellite tombs of imperial concubines, high officials and noble relations were dis- tributed over north and east part of the mausoleum, as well as tombs of convicts in the west. Inside the cemetery there were many palaces and houses inhabited by the tomb keepers and palace maids. Air photography, geophysical methods, remote sensing have been proved to be the most successful application in archaeological prospecting and surveying in recent years. In May 1998, we got several vertical images at a scale of 1:8000. Each im- age contains 30 photographs covering an area of 180km2 with an overlap of 65 In the autumn of 2000 about 2 hectares were surveyed with a Caesium magnetometer with a sensitivity of 0.01 Nanotesla (10 pT). This instrument was applied with duo- sensor configuration at 0.5 m traverse interval and 0.1 sec cycle, which corresponds to about 25 cm sample distance.

Assessment of doses to game animals in Finland.

PubMed

Vetikko, Virve; Kostiainen, Eila

2013-11-01

A study was carried out to assess the dose rates to game animals in Finland affected by the radioactive caesium deposition that occurred after the accident at the Chernobyl nuclear power plant in Ukraine in 1986. The aim of this assessment was to obtain new information on the dose rates to mammals and birds under Finnish conditions. Dose rates were calculated using the ERICA Assessment Tool developed within the EC 6th Framework Programme. The input data consisted of measured activity concentrations of (137)Cs and (134)Cs in soil and lake water samples and in flesh samples of selected animal species obtained for environmental monitoring. The study sites were located in the municipality of Lammi, Southern Finland, where the average (137)Cs deposition was 46.5 kBq m(-2) (1 October 1987). The study sites represented the areas receiving the highest deposition in Finland after the Chernobyl accident. The selected species included moose (Alces alces), arctic hare (Lepus timidus) and several bird species: black grouse (Tetrao tetrix), hazel hen (Bonasia bonasia), mallard (Anas platurhynchos), goldeneye (Bucephala clangula) and teal (Anas crecca). For moose, dose rates were calculated for the years 1986-1990 and for the 2000s. For all other species, maximal measured activity concentrations were used. The results showed that the dose rates to these species did not exceed the default screening level of 10 μGy h(-1) used as a protection criterion. The highest total dose rate (internal and external summed), 3.7 μGy h(-1), was observed for the arctic hare in 1986. Although the dose rate of 3.7 μGy h(-1) cannot be considered negligible given the uncertainties involved in predicting the dose rates, the possible harmful effects related to this dose rate are too small to be assessed based on current knowledge on the biological effects of low doses in mammals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reconstruction of sub-surface archaeological remains from magnetic data using neural computing.

NASA Astrophysics Data System (ADS)

Bescoby, D. J.; Cawley, G. C.; Chroston, P. N.

2003-04-01

The remains of a former Roman colonial settlement, once part of the classical city of Butrint in southern Albania have been the subject of a high resolution magnetic survey using a caesium-vapour magnetometer. The survey revealed the surviving remains of an extensive planned settlement and a number of outlying buildings, today buried beneath over 0.5 m of alluvial deposits. The aim of the current research is to derive a sub-surface model from the magnetic survey measurements, allowing an enhanced archaeological interpretation of the data. Neural computing techniques are used to perform the non-linear mapping between magnetic data and corresponding sub-surface model parameters. The adoption of neural computing paradigms potentially holds several advantages over other modelling techniques, allowing fast solutions for complex data, while having a high tolerance to noise. A multi-layer perceptron network with a feed-forward architecture is trained to estimate the shape and burial depth of wall foundations using a series of representative models as training data. Parameters used to forward model the training data sets are derived from a number of trial trench excavations targeted over features identified by the magnetic survey. The training of the network was optimized by first applying it to synthetic test data of known source parameters. Pre-processing of the network input data, including the use of a rotationally invariant transform, enhanced network performance and the efficiency of the training data. The approach provides good results when applied to real magnetic data, accurately predicting the depths and layout of wall foundations within the former settlement, verified by subsequent excavation. The resulting sub-surface model is derived from the averaged outputs of a ‘committee’ of five networks, trained with individualized training sets. Fuzzy logic inference has also been used to combine individual network outputs through correlation with data from a second geophysical technique, allowing the integration of data from a separate series of measurements.

Assessing the use of reflectance spectroscopy in determining CsCl stress in the model species Arabidopsis thaliana

DOE PAGES

Martinez, N. E.; Sharp, J. L.; Kuhne, W. W.; ...

2015-11-23

Here, reflectance spectroscopy is a rapid and non-destructive analytical technique that may be used for assessing plant stress, and has potential applications for use in remediation. Changes in reflectance such as that due to metal stress may occur before damage is visible, and existing studies have shown that metal stress does cause changes in plant reflectance. To further investigate the potential use of reflectance spectroscopy as a method for assessing metal stress in plants, an exploratory study was conducted in which Arabidopsis thaliana plants were treated twice weekly in a laboratory setting with varying levels (0, 0.5, or 5 mMmore » (millimolar)) of caesium chloride (CsCl) solution, and reflectance spectra were collected every week for three weeks using an Analytical Spectral Devices FieldSpec Pro spectroradiometer with both a contact probe (CP) and a field of view (FOV) probe at 36.8 and 66.7 cm, respectively, above the plant. Plants were harvested each week after spectra collection for determination of relative water content and chlorophyll content. A visual assessment of the plants was also conducted using point observations on a uniform grid of 81 points. A mixed-effects model analysis was conducted for each vegetation index (VI) considered to determine the effects of length of treatment, treatment level, view with which spectra were acquired, and the interactions of these terms. Two-way analyses of variance (ANOVAs) were performed on the aforementioned endpoints (e.g. chlorophyll content) to determine the significance of the effects of treatment level and length of treatment. Multiple linear regression (MLR) was used to develop a predictive model for each endpoint, considering VI acquired at each view (CP, high FOV, and low FOV). Of the 14 VI considered, 8 were included in the MLR models. Contact probe readings and FOV readings differed significantly, but FOV measurements were generally consistent at each height.« less

A measurement routine to determine 137Cs activities at steep mountain slopes

NASA Astrophysics Data System (ADS)

Schaub, Monika; Konz, Nadine; Meusburger, Katrin; Alewell, Chrstine

2010-05-01

Caesium-137 (137Cs) is a common tracer for soil erosion. So far, in-situ measurements in steep alpine environments have not often been done. Most studies have been carried out in arable lands and with Ge detectors. However, the NaI detector system is a good priced, easy to handle field instrument. A comparison of laboratory measurements with GeLi detector and in-situ measurements with NaI detector of 137Cs gamma soil radiation has been done in an alpine catchment (Urseren Valley, Swizerland). The aim of this study was to calibrate the in-situ NaI detector system for application at steep alpine slopes. Replicate samples from an altitudinal transect through the Urseren Valley were measured ex situ in the laboratory with a GeLi detector, and compared to in situ NaI detector measurements. Ex situ soil samples showed a big variability in 137Cs activities at a meter-scale. This large, small scale heterogeneity determined with the GeLi detector is smoothed out by uncollimated in-situ measurements with the NaI detector, which provide integrated estimates of 137Cs within the field of view of each measurement (3.1 m2). There was no dependency of 137Cs on pH, clay content and carbon content. However, a close relationship was determined between 137Cs and soil moisture. Thus, in-situ data must be corrected for soil moisture. Close correlation (R2 = 0.86) was found for 137Cs activities (in Bq kg-1) estimated with both, in-situ (NaI detector) and laboratory (GeLi detector) methods which proves the validity of the in-situ measurements with the NaI detector system. This paper describes the calibration of the NaI detector system for field application under elevated 137Cs activities originating from Chernobyl fallout.

Use of 137Cs measurements to estimate changes in soil erosion rates associated with changes in soil management practices on cultivated land.

PubMed

Schuller, P; Walling, D E; Sepúlveda, A; Trumper, R E; Rouanet, J L; Pino, I; Castillo, A

2004-05-01

Intensification of agricultural production in south-central Chile since the 1970s has caused problems of increased soil erosion and associated soil degradation. These problems have prompted a shift from conventional tillage to no-till management practices. Faced with the need to establish the impact of this shift in soil management on rates of soil loss, the use of caesium-137 (137Cs) measurements has been explored. A novel procedure for using measurements of the 137Cs depth distribution to estimate rates of soil loss at a sampling point under the original conventional tillage and after the shift to no-till management has been developed. This procedure has been successfully applied to a study site at Buenos Aires farm near Carahue in the 9th region of Chile. The results obtained indicate that the shift from conventional tillage to no-till management has caused net rates of soil loss to decrease to about 40% of those existing under conventional tillage. This assessment of the impact of introducing no-till management at the study site must, however, be seen as provisional, since only a limited number of sampling points were used. A simplified procedure aimed at documenting the reduction in erosion rates at additional sampling points, based solely on measurements of the 137Cs inventory of bulk cores and the 137Cs activity in the upper part of the soil has been developed and successfully tested at the study site. Previous application of 137Cs measurements to estimate erosion rates has been limited to estimation of medium-term erosion rates during the period extending from the beginning of fallout receipt to the time of sampling. The procedures described in this paper, which permits estimation of the change in erosion rates associated with a shift in land management practices, must be seen as representing a novel application of 137Cs measurements in soil erosion investigations.

Targeted versus statistical approaches to selecting parameters for modelling sediment provenance

NASA Astrophysics Data System (ADS)

Laceby, J. Patrick

2017-04-01

One effective field-based approach to modelling sediment provenance is the source fingerprinting technique. Arguably, one of the most important steps for this approach is selecting the appropriate suite of parameters or fingerprints used to model source contributions. Accordingly, approaches to selecting parameters for sediment source fingerprinting will be reviewed. Thereafter, opportunities and limitations of these approaches and some future research directions will be presented. For properties to be effective tracers of sediment, they must discriminate between sources whilst behaving conservatively. Conservative behavior is characterized by constancy in sediment properties, where the properties of sediment sources remain constant, or at the very least, any variation in these properties should occur in a predictable and measurable way. Therefore, properties selected for sediment source fingerprinting should remain constant through sediment detachment, transportation and deposition processes, or vary in a predictable and measurable way. One approach to select conservative properties for sediment source fingerprinting is to identify targeted tracers, such as caesium-137, that provide specific source information (e.g. surface versus subsurface origins). A second approach is to use statistical tests to select an optimal suite of conservative properties capable of modelling sediment provenance. In general, statistical approaches use a combination of a discrimination (e.g. Kruskal Wallis H-test, Mann-Whitney U-test) and parameter selection statistics (e.g. Discriminant Function Analysis or Principle Component Analysis). The challenge is that modelling sediment provenance is often not straightforward and there is increasing debate in the literature surrounding the most appropriate approach to selecting elements for modelling. Moving forward, it would be beneficial if researchers test their results with multiple modelling approaches, artificial mixtures, and multiple lines of evidence to provide secondary support to their initial modelling results. Indeed, element selection can greatly impact modelling results and having multiple lines of evidence will help provide confidence when modelling sediment provenance.

Portable gamma spectrometry: measuring soil erosion in-situ at four Critical Zone Observatories in P. R. China

NASA Astrophysics Data System (ADS)

Sanderson, N. K.; Green, S. M.; Chen, Z.; Wang, J.; Wang, Y.; Wang, R.; Yu, K.; Tu, C.; Jia, X.; Li, G.; Peng, X.; Quine, T. A.

2017-12-01

Detecting patterns of soil erosion, redistribution, and/soil nutrient loss is important for long-term soil conservation and agricultural sustainability. Caesium-137 (137Cs) and other fallout radionuclide inventories have been used over the the last 50 years to track soil erosion, transport and deposition on a catchment scale, and have been shown to be useful for informing models of temporal/spatial soil redistribution. Traditional sampling methods usually involves coring, grinding, sieving, sub-sampling and laboratory analysis using HPGe detectors, all of which can be costly and time consuming. In-situ measurements can provide a mechanism for assessment of 137Cs over larger areas that integrate the spatial variability, and expand turnover of analyses. Here, we assess the applicability of an in-situ approach based on radionuclide principles, and provide a comparison of the two approaches: laboratory vs. in-situ. The UK-China Critical Zone Observatory (CZO) programme provides an ideal research platform to assess the in-situ approach to measuring soil erosion: using a portable gamma spectrometer to determine 137Cs inventories. Four extensive field slope surveys were conducted in the CZO's, which covers four ecosystem types in China: karst, red soil, peri-urban, and loess plateau. In each CZO, 3-6 plots were measured along 2 slope transects, with 3 replicated 1 hour counts of 137Cs in each plot. In addition, 137Cs soil depth and bulk density profiles were also sampled for each plot, and lab-derived inventories calculated using traditional methods for comparison. Accurately and rapidly measuring 137Cs inventories using a portable field detector allows for a greater coverage of sampling locations and the potential for small-scale spatial integration, as well as the ability to re-visit sites over time and continually adapt and improve soil erosion/redistribution models, thus more effectively targeting areas of interest with reduced cost and time constraints.

Retrospective dosimetry of Iodine-131 exposures using Iodine-129 and Caesium-137 inventories in soils--A critical evaluation of the consequences of the Chernobyl accident in parts of Northern Ukraine.

PubMed

Michel, R; Daraoui, A; Gorny, M; Jakob, D; Sachse, R; Romantschuk, L D; Alfimov, V; Synal, H-A

2015-12-01

The radiation exposure of thyroid glands due to (131)I as a consequence of the Chernobyl accident was investigated retrospectively based on (129)I and (137)Cs inventories in soils in Northern Ukraine. To this end, soil samples from 60 settlements were investigated for (129)I, (127)I, and (137)Cs by AMS, ICP-MS and gamma-spectrometry, respectively. Sampling was performed between 2004 und 2007. In those parts of Northern Ukraine investigated here the (129)I and (137)Cs inventories are well correlated, the variability of the individual (129)I/(137)Cs ratios being, however, high. Both the (129)I and (137)Cs inventories in the individual 5 samples for each settlement allowed estimating the uncertainties of the inventories due to the variability of the radionuclide deposition and consequently of the retrospective dosimetry. Thyroid equivalent doses were calculated from the (129)I and the (137)Cs inventories using aggregated dose coefficients for 5-year old and 10-year-old children as well as for adults. The highest thyroid equivalent doses (calculated from (129)I inventories) were calculated for Wladimirowka with 30 Gy for 5-years-old children and 7 Gy for adults. In 35 settlements of contamination zone II the geometric mean of the thyroid equivalent doses was 2.0 Gy for 5-years-old children with a geometric standard deviation (GSD) of 3.0. For adults the geometric mean was 0.47 Gy also with a GSD of 3.0. In more than 25 settlements of contamination zone III the geometric means were 0.82 Gy for 5-years old children with a GSD of 1.8 and 0.21 Gy for adults (GSD 1.8). For 45 settlements, the results of the retrospective dosimetry could be compared with thyroid equivalent doses calculated using time-integrated (131)I activities of thyroids which were measured in 1986. Thus, a critical evaluation of the results was possible which demonstrated the general feasibility of the method, but also the associated uncertainties and limitations. Copyright © 2015 Elsevier Ltd. All rights reserved.

The secretion of alkali metal ions by the perfused cat pancreas as influenced by the composition and osmolality of the external environment and by inhibitors of metabolism and Na+, K+-ATPase activity

PubMed Central

Case, R. M.; Scratcherd, T.

1974-01-01

1. The secretion of sodium, potassium and lithium has been studied in the isolated cat pancreas, perfused with bicarbonate buffered saline solutions of varying composition and osmolality, and stimulated maximally with secretin. 2. Under isosmolal conditions, when perfusate sodium chloride was replaced by sucrose, sodium secretion and potassium secretion were directly related to perfusate sodium concentration, [Na]p. 3. When osmolality was varied by increasing or decreasing perfusate sodium chloride concentration, the secretion of sodium and of potassium were maximal at [Na]p of about 120 and 80 mM respectively. 4. At a given [Na]p, sodium secretion was greater under hypo-osmolal conditions than under isosmolal conditions. 5. When potassium concentration was varied over the range 0-130 mM under isosmolal conditions, by adjusting perfusate NaCl concentration, the secretion of potassium and of sodium were maximal at [K]p of about 50 and 10 mM respectively. Water flux was maximal at a [K]p of 10-15 mM. The concentration of potassium in the secretion was almost identical with that in the perfusate over the whole concentration range. 6. Replacement of perfusate sodium by lithium reduced the volume of secretion, though a small secretion was maintained even in the complete absence of sodium. The concentration of lithium in the secretion was generally slightly greater than that in the perfusate. 7. Omission of potassium from the perfusate reduced secretion by about 65%. Rubidium was a complete substitute for potassium; caesium was not. 8. Energy for secretion is derived largely from oxidative phosphorylation. Secretion was reduced by more than 90% under anaerobic conditions and in the presence of dinitrophenol or cyanide. Removal of glucose from the perfusate reduced secretion by more than 50% within 30 min; lactate was a complete substitute for glucose. 9. Ouabain, ethacrinic acid and frusimide, known inhibitors of Na+, K+-ATPase activity, all inhibited pancreatic electrolyte secretion. 10. The observations are interpreted with reference to the nature of active transport processes involved in pancreatic electrolyte secretion. PMID:4281836

Influence of H2 and D2 plasmas on the work function of caesiated materials

NASA Astrophysics Data System (ADS)

Friedl, R.; Fantz, U.

2017-08-01

Caesium-covered surfaces are used in negative hydrogen ion sources as a low work function converter for H-/D- surface production. The work function χ of the converter surface is one of the key parameters determining the performance of the ion source. Under idealized conditions, pure bulk Cs has 2.14 eV. However, residual gases at ion source background pressures of 10-7-10-6 mbar and the plasma surface interaction with the hydrogen discharge in front of the caesiated surface dynamically affect the actual surface work function. Necessary fundamental investigations on the resulting χ are performed at a dedicated laboratory experiment. Under the vacuum conditions of ion sources, the incorporation of impurities into the Cs layer leads to very stable Cs compounds. The result is a minimal work function of χvac ≈ 2.75 eV for Cs evaporation rates of up to 10 mg/h independent of substrate material and surface temperature (up to 260 °C). Moreover, a distinct degradation behavior can be observed in the absence of a Cs flux onto the surface leading to a deterioration of the work function by about 0.1 eV/h. However, in a hydrogen discharge with plasma parameters close to those of ion sources, fluxes of reactive hydrogen species and VUV photons impact on the surface which reduces the work function of the caesiated substrate down to about 2.6 eV even without Cs supply. Establishing a Cs flux onto the surface with ΓCs ≈ 1017 m-2 s-1 further enhances the work function obtaining values around 2.1 eV, which can be maintained stable for several hours of plasma exposure. Hence, Cs layers with work functions close to that of pure bulk Cs can be achieved for both H2 and D2 plasmas. Isotopic differences can be neglected within the measurement accuracy of about 0.1 eV due to comparable plasma parameters. Furthermore, after shutting down the Cs evaporation, continuing plasma exposure helps against degradation of the Cs layer resulting in a constant low work function for at least 1 h.

Dynamics of radiocesium exchange and interstratification in anhydrous clay interlayers: Bridging the atom and single crystal scales

NASA Astrophysics Data System (ADS)

Lammers, L. N.; Pestana, L. R.; Schaettle, K. B.; Head-Gordon, T.

2016-12-01

High structural charge clay minerals govern the transport and retention of radiocesium in soils and clay-rich geologic repositories. Cation exchange capacities in these phases are typically assumed to be limited to fast-exchanging basal and high-affinity edge sites, while ions in anhydrous interlayers, usually K+, are considered non-exchangeable. However, recent high resolution imaging and spectroscopic studies have demonstrated that Cs ions can in fact exchange with interlayer K without the formation of a hydrated intermediate.1,2 These exchange reactions result in sharp exchange fronts wherein K+ ions are completely replaced by Cs+ at the exchange interface, and the rate of exchange varies from layer to layer, resulting in the formation of interstratified structures (i.e., randomly alternating layers of exchanged and pristine interlayers). Currently, this process cannot be explained by any known exchange mechanism, and consequently, no kinetic expressions are available to account for this phenomenon in models of subsurface radiocesium fate and transport. We present a mesoscale model for direct exchange in anhydrous clay interlayers that is based on the kinetics of single ion migration events. Single atom migration kinetics derived from density functional theory (DFT) calculations are used as inputs to kinetic Monte Carlo (kMC) simulations, which capture the collective dynamics of the exchange process over length- and timescales relevant for implementation in reactive transport models. Potential energy surfaces derived from DFT demonstrate that exchange of Cs+ for K+ in anhydrous interlayers lowers the energy barrier to K ion migration by 145 kJ/mol, leading to a positive feedback mechanism that generates atomically sharp exchange fronts. Our work demonstrates the application of "coarse-graining" techniques to develop models for processes with characteristic length- and timescales not accessible by direct atomistic simulation. 1 Okumura T. et al. (2014) Direct observation of cesium at the interlayer region in phlogopite mica. Microscopy 63(1), 65-72. 2 Fuller A. J. et al. (2015) Caesium incorporation and retention in illite interlayers. Appl. Clay Sci. 108, 128-134.

Is exposure to ionising radiation associated with childhood cardiac arrhythmia in the Russian territories contaminated by the Chernobyl fallout? A cross-sectional population-based study

PubMed Central

Clero, Enora; Doroshchenko, Vladimir; Silenok, Aleksandr; Kurnosova, Irina; Butsenin, Andrei; Denjoy, Isabelle; Franck, Didier; Heuze, Jean-Pierre; Gourmelon, Patrick

2018-01-01

Objective To investigate childhood cardiac arrhythmia and chronic exposure to caesium-137 (137Cs) resulting from the Chernobyl accident. Design Prospective cross-sectional study using exposed/unexposed design conducted in the Bryansk region from May 2009 to May 2013 on children selected on the basis of 137Cs soil deposition: control territories ([137Cs]<37 kBq per square metre, where children were considered as unexposed) and contaminated territories ([137Cs]>555 kBq per square metre, where children were considered as exposed). Setting Russian territories affected by the Chernobyl fallout (Bryansk region). Participants This cross-sectional study included 18 152 children aged 2–18 years and living in the Bryansk region (Russia). Main outcome measures All children received three medical examinations (ECG, echocardiography and 137Cs whole-body activity measurement) and some of them were given with a 24-hour Holter monitoring and blood tests. Results Cardiac arrhythmia was diagnosed in 1172 children living in contaminated territories and 1354 children living in control territories. The crude prevalence estimated to 13.3% in contaminated territories was significantly lower than in control territories with 15.2% over the period 2009–2013 (P<0.001). Considering 137Cs whole-body burden as exposure, cardiac arrhythmia was found in 449 contaminated children and 2077 uncontaminated children, corresponding to an estimated crude prevalence of 14.5% and 14.2%, respectively, which does not differ significantly (P=0.74). Also, we investigated the association between territory, exposure to 137Cs and cardiac arrhythmia: the adjusted OR was not significant (0.90 with 95% CI 0.81 to 1.00; P=0.06) for the territory. For 137Cs whole-body burden, the ORs close to 1 did not reach statistical significance (P for trend=0.97). Conclusion This study does not observe an association between cardiac arrhythmia and 137Cs deposition levels in the Bryansk region exposed to Chernobyl fallout. The suspected increase of cardiac arrhythmia in children exposed to Chernobyl fallout is not confirmed. PMID:29581199

Backward-in-time methods to simulate large-scale transport and mixing in the ocean

NASA Astrophysics Data System (ADS)

Prants, S. V.

2015-06-01

In oceanography and meteorology, it is important to know not only where water or air masses are headed for, but also where they came from as well. For example, it is important to find unknown sources of oil spills in the ocean and of dangerous substance plumes in the atmosphere. It is impossible with the help of conventional ocean and atmospheric numerical circulation models to extrapolate backward from the observed plumes to find the source because those models cannot be reversed in time. We review here recently elaborated backward-in-time numerical methods to identify and study mesoscale eddies in the ocean and to compute where those waters came from to a given area. The area under study is populated with a large number of artificial tracers that are advected backward in time in a given velocity field that is supposed to be known analytically or numerically, or from satellite and radar measurements. After integrating advection equations, one gets positions of each tracer on a fixed day in the past and can identify from known destinations a particle positions at earlier times. The results provided show that the method is efficient, for example, in estimating probabilities to find increased concentrations of radionuclides and other pollutants in oceanic mesoscale eddies. The backward-in-time methods are illustrated in this paper with a few examples. Backward-in-time Lagrangian maps are applied to identify eddies in satellite-derived and numerically generated velocity fields and to document the pathways by which they exchange water with their surroundings. Backward-in-time trapping maps are used to identify mesoscale eddies in the altimetric velocity field with a risk to be contaminated by Fukushima-derived radionuclides. The results of simulations are compared with in situ mesurement of caesium concentration in sea water samples collected in a recent research vessel cruise in the area to the east of Japan. Backward-in-time latitudinal maps and the corresponding material-line techniques are applied to document transport of water masses across strong currents. Backward-in-time drift maps are shown to be useful in identifying the Lagrangian fronts favorable for fishery.

Consensus building for interlaboratory studies, key comparisons, and meta-analysis

NASA Astrophysics Data System (ADS)

Koepke, Amanda; Lafarge, Thomas; Possolo, Antonio; Toman, Blaza

2017-06-01

Interlaboratory studies in measurement science, including key comparisons, and meta-analyses in several fields, including medicine, serve to intercompare measurement results obtained independently, and typically produce a consensus value for the common measurand that blends the values measured by the participants. Since interlaboratory studies and meta-analyses reveal and quantify differences between measured values, regardless of the underlying causes for such differences, they also provide so-called ‘top-down’ evaluations of measurement uncertainty. Measured values are often substantially over-dispersed by comparison with their individual, stated uncertainties, thus suggesting the existence of yet unrecognized sources of uncertainty (dark uncertainty). We contrast two different approaches to take dark uncertainty into account both in the computation of consensus values and in the evaluation of the associated uncertainty, which have traditionally been preferred by different scientific communities. One inflates the stated uncertainties by a multiplicative factor. The other adds laboratory-specific ‘effects’ to the value of the measurand. After distinguishing what we call recipe-based and model-based approaches to data reductions in interlaboratory studies, we state six guiding principles that should inform such reductions. These principles favor model-based approaches that expose and facilitate the critical assessment of validating assumptions, and give preeminence to substantive criteria to determine which measurement results to include, and which to exclude, as opposed to purely statistical considerations, and also how to weigh them. Following an overview of maximum likelihood methods, three general purpose procedures for data reduction are described in detail, including explanations of how the consensus value and degrees of equivalence are computed, and the associated uncertainty evaluated: the DerSimonian-Laird procedure; a hierarchical Bayesian procedure; and the Linear Pool. These three procedures have been implemented and made widely accessible in a Web-based application (NIST Consensus Builder). We illustrate principles, statistical models, and data reduction procedures in four examples: (i) the measurement of the Newtonian constant of gravitation; (ii) the measurement of the half-lives of radioactive isotopes of caesium and strontium; (iii) the comparison of two alternative treatments for carotid artery stenosis; and (iv) a key comparison where the measurand was the calibration factor of a radio-frequency power sensor.

High-resolution 17O double-rotation NMR characterization of ring and non-ring oxygen in vitreous B2O3.

PubMed

Wong, Alan; Howes, Andy P; Parkinson, Ben; Anupõld, Tiit; Samoson, Ago; Holland, Diane; Dupree, Ray

2009-08-28

The application of double rotation (DOR) NMR to crystalline materials (both inorganic and organic) has made tremendous strides in providing site-specific information about materials in recent years. However (17)O DOR has yet to demonstrate its potential in disordered materials such as glasses. In the present study, we have successfully recorded high resolution (17)O DOR spectra of vitreous B(2)O(3) (v-B(2)O(3)), a highly effective glass-forming oxide of considerable technological importance. Two distinct oxygen sites are resolved and a complete set of (17)O NMR parameters were determined from the DOR spectra. These were assigned to oxygen atoms in the planar boroxol ring [B(3)O(6)] and in the non-boroxol [BO(3)] groups which share oxygen with the ring boron atoms. This assignment was based on the similarity of all of their (17)O parameters with those found by DFT calculation for caesium enneaborate, Cs(2)O.9B(2)O(3), which has two boroxol rings in its structure. The boroxol ring oxygens have a more positive chemical shift, a larger shift anisotropy and a smaller electric field gradient than non ring oxygens (O(R): delta(iso) = 100 +/- 1 ppm, span = 180 +/- 20 ppm, skew = -0.4 +/- 0.1, P(q) = 5.0 +/- 0.2 MHz; O(NR): delta(iso) = 86 +/- 1 ppm, span = 100 +/- 20 ppm, skew = 0.1 +/- 0.1, P(q) = 5.7 +/- 0.2 MHz). The relative proportions of the two sites in v-B(2)O(3) are approximately 1 : 1, as expected if all three boron atoms in the boroxol ring are each connected to one oxygen in a linking [BO(3)] group and there are very few [BO(3)]-[BO(3)] linkages. We see no evidence for a third oxygen site such as has been reported in an earlier study of v-B(2)O(3). This work demonstrates the potential of (17)O DOR to provide site-specific information in disordered materials.

Decommissioning of magnox Ltd fuel cooling pond facilities in the UK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bertoncini, Carlo

2013-07-01

Magnox reactors were the first generation of nuclear power stations built in the UK; ten sites in total, of which, nine had wet fuel routes with cooling ponds. Five ponds are currently in a decommissioning phase; this paper will focus primarily on Hunterston-A (HNA) Site and the central programme of work which governs its management. During its operation, the Cartridge Cooling Pond at HNA was used to receive the spent fuel discharged from the Site's two reactors, it was then stored for cooling purposes prior to dispatch off site. The current decommissioning phase focusses on draining the 6500 m{sup 3}more » pond. Due to the Site's limited caesium removal facilities, a stand-alone effluent treatment plant was constructed to improve abatement and reduce the pond activity from 200 to 0.7 Bq/ml (β). This was necessary due to increased environmental standards introduced since the site had ceased generation ten years previously. Early characterisation and experience from other sites concluded that if the pond were to be drained without any treatment to the walls, doses to the Operators, during subsequent decommissioning works, would routinely be in excess of 1 mSv.hr{sup -1}(γ). An opportunity was realised within the Ponds Programme that if the surface layer of the pond walls were to be removed during drain-down, ambient dose rates would be reduced by a factor of 10; this would allow for more cost-effective decommissioning options in the future. Ultrahigh pressure water jetting was tested and proved to yield a ∼95% total-activity reduction on treated surfaces. Challenges were overcome in providing safe and secure access to Decommissioning Operators to perform this operation by means of floating platforms on the surface of the pond. As strategies to clear facilities to exemption levels are becoming both cost prohibitive and not reasonably practicable, work is now underway in the Programme to determine the optimum condition for entry into long-term quiescent storage, prior to final demolition. This paper will discuss the strategy and techniques which led to Magnox Ltd ponds to be of national and international interest to the nuclear community. (authors)« less

Atmospheric removal times of the aerosol-bound radionuclides 137Cs and 131I during the months after the Fukushima Dai-ichi nuclear power plant accident - a constraint for air quality and climate models

NASA Astrophysics Data System (ADS)

Kristiansen, N. I.; Stohl, A.; Wotawa, G.

2012-05-01

Caesium-137 (137Cs) and iodine-131 (131I) are radionuclides of particular concern during nuclear accidents, because they are emitted in large amounts and are of significant health impact. 137Cs and 131I attach to the ambient accumulation-mode (AM) aerosols and share their fate as the aerosols are removed from the atmosphere by scavenging within clouds, precipitation and dry deposition. Here, we estimate their removal times from the atmosphere using a unique high-precision global measurement data set collected over several months after the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. The noble gas xenon-133 (133Xe), also released during the accident, served as a passive tracer of air mass transport for determining the removal times of 137Cs and 131I via the decrease in the measured ratios 137Cs/133Xe and 131I/133Xe over time. After correction for radioactive decay, the 137Cs/133Xe ratios reflect the removal of aerosols by wet and dry deposition, whereas the 131I/133Xe ratios are also influenced by aerosol production from gaseous 131I. We find removal times for 137Cs of 10.0-13.9 days and for 131I of 17.1-24.2 days during April and May 2011. We discuss possible caveats (e.g. late emissions, resuspension) that can affect the results, and compare the 137Cs removal times with observation-based and modeled aerosol lifetimes. Our 137Cs removal time of 10.0-13.9 days should be representative of a "background" AM aerosol well mixed in the extratropical Northern Hemisphere troposphere. It is expected that the lifetime of this vertically mixed background aerosol is longer than the lifetime of AM aerosols originating from surface sources. However, the substantial difference to the mean lifetimes of AM aerosols obtained from aerosol models, typically in the range of 3-7 days, warrants further research on the cause of this discrepancy. Too short modeled AM aerosol lifetimes would have serious implications for air quality and climate model predictions.

Validating the use of 137Cs and 210Pbex measurements to estimate rates of soil loss from cultivated land in southern Italy.

PubMed

Porto, Paolo; Walling, Des E

2012-04-01

Soil erosion represents an important threat to the long-term sustainability of agriculture and forestry in many areas of the world, including southern Italy. Numerous models and prediction procedures have been developed to estimate rates of soil loss and soil redistribution, based on the local topography, hydrometeorology, soil type and land management. However, there remains an important need for empirical measurements to provide a basis for validating and calibrating such models and prediction procedures as well as to support specific investigations and experiments. In this context, erosion plots provide useful information on gross rates of soil loss, but are unable to document the efficiency of the onward transfer of the eroded sediment within a field and towards the stream system, and thus net rates of soil loss from larger areas. The use of environmental radionuclides, particularly caesium-137 ((137)Cs) and excess lead-210 ((210)Pb(ex)), as a means of estimating rates of soil erosion and deposition has attracted increasing attention in recent years and the approach has now been recognised as possessing several important advantages. In order to provide further confirmation of the validity of the estimates of longer-term erosion and soil redistribution rates provided by (137)Cs and (210)Pb(ex) measurements, there is a need for studies aimed explicitly at validating the results obtained. In this context, the authors directed attention to the potential offered by a set of small erosion plots located near Reggio Calabria in southern Italy, for validating estimates of soil loss provided by (137)Cs and (210)Pb(ex) measurements. A preliminary assessment suggested that, notwithstanding the limitations and constraints involved, a worthwhile investigation aimed at validating the use of (137)Cs and (210)Pb(ex) measurements to estimate rates of soil loss from cultivated land could be undertaken. The results demonstrate a close consistency between the measured rates of soil loss and the estimates provided by the (137)Cs and (210)Pb(ex) measurements and can therefore been seen as validating the use of these fallout radionuclides to document soil erosion rates in that environment. Further studies are clearly required to exploit other opportunities for validation in contrasting environments and under different land use conditions. Copyright © 2011 Elsevier Ltd. All rights reserved.

NASA Astrophysics Data System (ADS)

Porto, Paolo

2016-05-01

IAEA-TECDOC-1741 'Guidelines for Using Fallout Radionuclides to Assess Erosion and Effectiveness of Soil Conservation Strategies' represents a product of a long-term initiative by the International Atomic Energy Agency (IAEA) to promote the use of fallout radionuclides (FRNs) for investigating soil erosion and soil and sediment redistribution processes in the environment. Numerous papers dealing with the use of FRNs, and more particularly caesium-137 (137Cs), excess lead-210 (210Pbex), and beryllium-7 (7Be), for this purpose have been published in recent years and FRNs are now widely used in soil erosion investigations around the world (see among the others, Loughran et al., 1993; Mabit et al., 2008; Navas et al., 2005; Owens et al., 1996; Porto et al., 2001, 2013; Wallbrink and Murray, 1996; Walling, 2012; Zhang et al., 1990). There have, however, been few manuals or related publications produced to provide guidelines for the application of the approach. This deficiency has arguably hindered standardisation of the procedures used by different researchers, with the result that there is often considerable variation between studies in the details of the approach used and the nature of the data generated. The Handbook for the Assessment of Soil Erosion and Sedimentation Using Environmental Radionuclides edited by Felipe Zapata, an IAEA officer, and published in 2002 (Zapata, 2002) was an important milestone in progressing towards standardisation. However, it is now becoming outdated, not least because it focuses on 137Cs rather than covering all three FRNs. There have also been many developments in the field since the Handbook was produced. This recently published volume must therefore be welcomed as updating that Handbook and, more particularly, covering the application of all three FRNs. It draws on the experience of around 30 researchers from around the world, who have been involved with the recent IAEA Coordinated Research Projects (CRPs) linked to the use of FRNs and provides a clear demonstration of the value of such projects and the international collaboration that they promote. The contributors were coordinated by Dr. Lionel Mabit, a well-known researcher in the field, who is a member of staff within the Soil and Water Management and Crop Nutrition Section of the joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, based in Vienna, Austria.

Is exposure to ionising radiation associated with childhood cardiac arrhythmia in the Russian territories contaminated by the Chernobyl fallout? A cross-sectional population-based study.

PubMed

Jourdain, Jean-Rene; Landon, Geraldine; Clero, Enora; Doroshchenko, Vladimir; Silenok, Aleksandr; Kurnosova, Irina; Butsenin, Andrei; Denjoy, Isabelle; Franck, Didier; Heuze, Jean-Pierre; Gourmelon, Patrick

2018-03-25

To investigate childhood cardiac arrhythmia and chronic exposure to caesium-137 ( 137 Cs) resulting from the Chernobyl accident. Prospective cross-sectional study using exposed/unexposed design conducted in the Bryansk region from May 2009 to May 2013 on children selected on the basis of 137 Cs soil deposition: control territories ([ 137 Cs]<37 kBq per square metre, where children were considered as unexposed) and contaminated territories ([ 137 Cs]>555 kBq per square metre, where children were considered as exposed). Russian territories affected by the Chernobyl fallout (Bryansk region). This cross-sectional study included 18 152 children aged 2-18 years and living in the Bryansk region (Russia). All children received three medical examinations (ECG, echocardiography and 137 Cs whole-body activity measurement) and some of them were given with a 24-hour Holter monitoring and blood tests. Cardiac arrhythmia was diagnosed in 1172 children living in contaminated territories and 1354 children living in control territories. The crude prevalence estimated to 13.3% in contaminated territories was significantly lower than in control territories with 15.2% over the period 2009-2013 (P<0.001). Considering 137 Cs whole-body burden as exposure, cardiac arrhythmia was found in 449 contaminated children and 2077 uncontaminated children, corresponding to an estimated crude prevalence of 14.5% and 14.2%, respectively, which does not differ significantly (P=0.74). Also, we investigated the association between territory, exposure to 137 Cs and cardiac arrhythmia: the adjusted OR was not significant (0.90 with 95% CI 0.81 to 1.00; P=0.06) for the territory. For 137 Cs whole-body burden, the ORs close to 1 did not reach statistical significance (P for trend=0.97). This study does not observe an association between cardiac arrhythmia and 137 Cs deposition levels in the Bryansk region exposed to Chernobyl fallout. The suspected increase of cardiac arrhythmia in children exposed to Chernobyl fallout is not confirmed. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Particle tracking in the eastern Irish Sea

NASA Astrophysics Data System (ADS)

Wolf, Judith; Amoudry, Karen; Phillips, Hazel; Brown, Jenny

2017-04-01

The unstructured grid finite volume community ocean model (FVCOM) has been applied to the west coast of the UK, in order to examine the circulation and transport in the eastern Irish Sea. Tides, freshwater river discharge and meteorological forcing for the year 2008 were used to force the baroclinic hydrodynamic circulation. The hydrodynamics of the Irish Sea are largely governed by the semidiurnal tide, which has a tidal range reaching 10m at Liverpool is the eastern Irish Sea. Tidal currents reach 1 ms-1 over the majority of the area, which means that much of Irish Sea is vertically well-mixed throughout the year period, with a few areas affected by seasonal stratification, such as the cyclonic gyre in the deep channel off Ireland in the western Irish Sea which experiences thermal stratification in summer. In Liverpool Bay, horizontal density gradients, created through freshwater influence from estuaries along the coastline interact with the strong tidal current to produce a phenomenon known as strain-induced periodic stratification (SIPS). There are water quality concerns due to the tendency to eutrophication, as the area is often exposed to industrial pollution and excess nutrients from effluent waters and rivers. There is also concern about the fate of radioactive materials discharged from the Sellafield nuclear reprocessing plant since 1952. In addition to the present discharges from the site, it has been estimated that it is likely that all of the americium and plutonium and around 10% of the caesium entering the Irish Sea were originally assimilated into deposits of silt and mud sediments; this material may be regarded as a considerable potential source of radionuclides. Determining suspended sediment pathways in this region is important in order to identify potential areas vulnerable to deposition of radioactive material, particularly as radionuclide uptake onto sediments takes place in the offshore 'mud patch' before returning to the coast to be deposited in saltmarshes. A particle tracking experiment has been carried out in order to examine advection and dispersion of particles released at different levels in the water column. The particle tracking has been carried out using the FVCOM offline particle tracking software, using multiple particle releases at select locations. The results are used to identify possible fates of suspended sediment and associated pollutants.

Reversibility of radiocaesium sorption on illite

NASA Astrophysics Data System (ADS)

de Koning, Arjan; Comans, Rob N. J.

2004-07-01

Adsorption of trace amounts of radiocaesium on NH 4-, K-, and Na-saturated Fithian illite and subsequent desorption by 1 M NH 4 showed that a substantial amount of radiocaesium (44%, 46%, and 91% for NH 4-, K-, and Na-illite, respectively) cannot be desorbed after only 5 min of adsorption. Our results suggest that this instantaneous fixation is caused by the collapse of the frayed edges of the clay mineral and the relatively high concentration of radiocaesium building up in solution in the batch desorption experiments. Consequently, commonly applied high-NH 4 extractions underestimate truly exchangeable amounts of radiocaesium in soils and sediments containing illitic clay minerals. The rate of desorption of trace amounts of radiocaesium from the solids using high NH 4 or Cs concentrations has a half-life of about 2 yr, reflecting radiocaesium desorption from (partially) collapsed interlayers. Extraction of radiocaesium from illite after 5 min of contact time with a Cs-selective adsorbent or a 1 × 10 -6 M CsCl solution shows that 100% of the bound radiocaesium is readily available. The desorption rate in the presence of a Cs-selective adsorbent has a half-life of about 0.2 yr. Desorption of radiocaesium from illite using different ammonium concentrations shows that radiocaesium partitioning follows reversible ion-exchange theory if the NH 4 concentration is below 1 × 10 -4 M, and sufficient time (weeks) is allowed for the reaction to proceed. Thus, radiocaesium sorption reversibility in the natural environment is much higher than generally assumed, and equilibrium solid/liquid partitioning may be assumed for the long-term modelling of radiocaesium mobility in the natural environment. In the particular case of anoxic freshwater sediments with very high NH 4 concentrations in the pore waters (up to several mmol.L -1), collapse of the frayed edges of illite may occur, influencing radiocaesium partitioning. If collapse occurs before radiocaesium adsorbs to illite, high caesium sorption reversibility as measured by high-NH 4 extraction can be expected because further collapse of the frayed edges during the extraction procedure will be limited. This effect has indeed been observed earlier in the extraction of radiocaesium from anoxic freshwater sediments with high-NH 4 solutions and was as yet unexplained.

Excess Lead-210 and Plutonium-239+240: Two suitable radiogenic soil erosion tracers for mountain grassland sites.

PubMed

Meusburger, K; Porto, P; Mabit, L; La Spada, C; Arata, L; Alewell, C

2018-01-01

The expected growing population and challenges associated with globalisation will increase local food and feed demands and enhance the pressure on local and regional upland soil resources. In light of these potential future developments it is necessary to define sustainable land use and tolerable soil loss rates with methods applicable and adapted to mountainous areas. Fallout-radionuclides (FRNs) are proven techniques to increase our knowledge about the status and resilience of agro-ecosystems. However, the use of the Caesium-137 ( 137 Cs) method is complicated in the European Alps due to its heterogeneous input and the timing of the Chernobyl fallout, which occurred during a few single rain events on partly snow covered ground. Other radioisotopic techniques have been proposed to overcome these limitations. The objective of this study is to evaluate the suitability of excess Lead-210 ( 210 Pb ex ) and Plutonium-239+240 ( 239+240 Pu) as soil erosion tracers for three different grassland management types at the steep slopes (slope angles between 35 and 38°) located in the Central Swiss Alps. All three FRNs identified pastures as having the highest mean (± standard deviation) net soil loss of -6.7 ± 1.1, -9.8 ± 6.8 and -7.0 ± 5.2 Mg ha -1 yr -1 for 137 Cs, 210 Pb ex and 239+240 Pu, respectively. A mean soil loss of -5.7 ± 1.5, -5.2 ± 1.5 and-5.6 ± 2.1 was assessed for hayfields and the lowest rates were established for pastures with dwarf-shrubs (-5.2 ± 2.5, -4.5 ± 2.5 and -3.3 ± 2.4 Mg ha -1 yr -1 for 137 Cs, 210 Pb ex and 239+240 Pu, respectively). These rates, evaluated at sites with an elevated soil erosion risk exceed the respective soil production rates. Among the three FRN methods used, 239+240 Pu appears as the most promising tracer in terms of measurement uncertainty and reduced small scale variability (CV of 13%). Despite a higher level of uncertainty, 210 Pb ex produced comparable results, with a wide range of erosion rates sensitive to changes in grassland management. 210 Pb ex can then be as well considered as a suitable soil tracer to investigate alpine agroecosystems. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Atmospheric removal times of the aerosol-bound radionuclides 137Cs and 131I measured after the Fukushima Dai-ichi nuclear accident - a constraint for air quality and climate models

NASA Astrophysics Data System (ADS)

Kristiansen, N. I.; Stohl, A.; Wotawa, G.

2012-11-01

Caesium-137 (137Cs) and iodine-131 (131I) are radionuclides of particular concern during nuclear accidents, because they are emitted in large amounts and are of significant health impact. 137Cs and 131I attach to the ambient accumulation-mode (AM) aerosols and share their fate as the aerosols are removed from the atmosphere by scavenging within clouds, precipitation and dry deposition. Here, we estimate their removal times from the atmosphere using a unique high-precision global measurement data set collected over several months after the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. The noble gas xenon-133 (133Xe), also released during the accident, served as a passive tracer of air mass transport for determining the removal times of 137Cs and 131I via the decrease in the measured ratios 137Cs/133Xe and 131I/133Xe over time. After correction for radioactive decay, the 137Cs/133Xe ratios reflect the removal of aerosols by wet and dry deposition, whereas the 131I/133Xe ratios are also influenced by aerosol production from gaseous 131I. We find removal times for 137Cs of 10.0-13.9 days and for 131I of 17.1-24.2 days during April and May 2011. The removal time of 131I is longer due to the aerosol production from gaseous 131I, thus the removal time for 137Cs serves as a better estimate for aerosol lifetime. The removal time of 131I is of interest for semi-volatile species. We discuss possible caveats (e.g. late emissions, resuspension) that can affect the results, and compare the 137Cs removal times with observation-based and modeled aerosol lifetimes. Our 137Cs removal time of 10.0-13.9 days should be representative of a "background" AM aerosol well mixed in the extratropical Northern Hemisphere troposphere. It is expected that the lifetime of this vertically mixed background aerosol is longer than the lifetime of fresh AM aerosols directly emitted from surface sources. However, the substantial difference to the mean lifetimes of AM aerosols obtained from aerosol models, typically in the range of 3-7 days, warrants further research on the cause of this discrepancy. Too short modeled AM aerosol lifetimes would have serious implications for air quality and climate model predictions.

Status of the Negative Ion Based Heating and Diagnostic Neutral Beams for ITER

NASA Astrophysics Data System (ADS)

Schunke, B.; Bora, D.; Hemsworth, R.; Tanga, A.

2009-03-01

The current baseline of ITER foresees 2 Heating Neutral Beam (HNB's) systems based on negative ion technology, each accelerating to 1 MeV 40 A of D- and capable of delivering 16.5 MW of D0 to the ITER plasma, with a 3rd HNB injector foreseen as an upgrade option [1]. In addition a dedicated Diagnostic Neutral Beam (DNB) accelerating 60 A of H- to 100 keV will inject ≈15 A equivalent of H0 for charge exchange recombination spectroscopy and other diagnostics. Recently the RF driven negative ion source developed by IPP Garching has replaced the filamented ion source as the reference ITER design. The RF source developed at IPP, which is approximately a quarter scale of the source needed for ITER, is expected to have reduced caesium consumption compared to the filamented arc driven ion source. The RF driven source has demonstrated adequate accelerated D- and H- current densities as well as long-pulse operation [2, 3]. It is foreseen that the HNB's and the DNB will use the same negative ion source. Experiments with a half ITER-size ion source are on-going at IPP and the operation of a full-scale ion source will be demonstrated, at full power and pulse length, in the dedicated Ion Source Test Bed (ISTF), which will be part of the Neutral Beam Test Facility (NBTF), in Padua, Italy. This facility will carry out the necessary R&D for the HNB's for ITER and demonstrate operation of the full-scale HNB beamline. An overview of the current status of the neutral beam (NB) systems and the chosen configuration will be given and the ongoing integration effort into the ITER plant will be highlighted. It will be demonstrated how installation and maintenance logistics have influenced the design, notably the top access scheme facilitating access for maintenance and installation. The impact of the ITER Design Review and recent design change requests (DCRs) will be briefly discussed, including start-up and commissioning issues. The low current hydrogen phase now envisaged for start-up imposed specific requirements for operating the HNB's at full beam power. It has been decided to address the shinethrough issue by installing wall armour protection, which increases the operational space in all scenarios. Other NB related issues identified by the Design Review process will be discussed and the possible changes to the ITER baseline indicated.

ICRP Publication 137: Occupational Intakes of Radionuclides: Part 3.

PubMed

Paquet, F; Bailey, M R; Leggett, R W; Lipsztein, J; Marsh, J; Fell, T P; Smith, T; Nosske, D; Eckerman, K F; Berkovski, V; Blanchardon, E; Gregoratto, D; Harrison, J D

2017-12-01

The 2007 Recommendations of the International Commission on Radiological Protection (ICRP, 2007) introduced changes that affect the calculation of effective dose, and implied a revision of the dose coefficients for internal exposure, published previously in the Publication 30 series (ICRP, 1979, 1980, 1981, 1988) and Publication 68 (ICRP, 1994). In addition, new data are now available that support an update of the radionuclide-specific information given in Publications 54 and 78 (ICRP, 1988a, 1997b) for the design of monitoring programmes and retrospective assessment of occupational internal doses. Provision of new biokinetic models, dose coefficients, monitoring methods, and bioassay data was performed by Committee 2, Task Group 21 on Internal Dosimetry, and Task Group 4 on Dose Calculations. A new series, the Occupational Intakes of Radionuclides (OIR) series, will replace the Publication 30 series and Publications 54, 68, and 78. OIR Part 1 has been issued (ICRP, 2015), and describes the assessment of internal occupational exposure to radionuclides, biokinetic and dosimetric models, methods of individual and workplace monitoring, and general aspects of retrospective dose assessment. OIR Part 2 (ICRP, 2016), this current publication and upcoming publications in the OIR series (Parts 4 and 5) provide data on individual elements and their radioisotopes, including information on chemical forms encountered in the workplace; a list of principal radioisotopes and their physical half-lives and decay modes; the parameter values of the reference biokinetic model; and data on monitoring techniques for the radioisotopes encountered most commonly in workplaces. Reviews of data on inhalation, ingestion, and systemic biokinetics are also provided for most of the elements. Dosimetric data provided in the printed publications of the OIR series include tables of committed effective dose per intake (Sv Bq−1 intake) for inhalation and ingestion, tables of committed effective dose per content (Sv Bq−1 measurement) for inhalation, and graphs of retention and excretion data per Bq intake for inhalation. These data are provided for all absorption types and for the most common isotope(s) of each element. The electronic annex that accompanies the OIR series of publications contains a comprehensive set of committed effective and equivalent dose coefficients, committed effective dose per content functions, and reference bioassay functions. Data are provided for inhalation, ingestion, and direct input to blood. This third publication in the series provides the above data for the following elements: ruthenium (Ru), antimony (Sb), tellurium (Te), iodine (I), caesium (Cs), barium (Ba), iridium (Ir), lead (Pb), bismuth (Bi), polonium (Po), radon (Rn), radium (Ra), thorium (Th), and uranium (U).

Measurement of caesium-137 in the human body using a whole body counter

NASA Astrophysics Data System (ADS)

Elessawi, Elkhadra Abdulmula

Gamma radiation in the environment is mainly due to naturally occurring radionuclides. However, there is also a contribution from anthropogenic radionuclides such as 137Cs which originate from nuclear fission processes. Since 1986, the accident at the Chernobyl power plant has been a significant source of artificial environmental radioactivity. In order to assess the radiological impact of these radionuclides, it is necessary to measure their activities in samples drawn from the environment and in plants and animals including human populations. The whole body counter (WBC) at the University Hospital of Wales in Cardiff makes in vivo measurements of gamma emitting radionuclides using a scanning ring of six large-volume thallium-doped sodium iodide (Nal(Tl)) scintillation detectors. In this work the WBC was upgraded by the addition of two high purity germanium (HPGe) detectors. The performance and suitability of the detection systems were evaluated by comparing the detection limits for Cs. Sensitivities were measured using sources of known activity in a water filled anthropomorphic phantom and theoretical minimum detectable count-rates were estimated from phantom background pulse height spectra. The theoretical minimum detectable activity was about 24 Bq for the combination of six Nal(Tl) detectors whereas for the individual HPGe detectors it was 64 Bq and 65 Bq, despite the much improved energy resolution Activities of 137Cs in the human body between 1993 and 2007 were estimated from the background Nal(Tl) spectra of 813 patients and compared with recent measurements in 14 volunteers. The body burden of Cs in Cardiff patients increased from an average of about 60 Bq in the early and mid 1990s to a maximum of about 100 Bq in 2000. By 2007 it had decreased to about 40 Bq. This latter value was similar to that of Cardiff residents at the time of the Chernobyl accident and to that of the volunteers measured in 2007 (51 Bq). However, it was less than the mean activity of Cardiff residents in 1988 (130 Bq) indicating an overall decrease over a period of about 20 years. The variation in the in vivo activity is probably due to complex inter-relationships between a number of factors such as the removal of deposited 137Cs into the sea by rainfall, individual dietary choices, the imposition and removal of restrictions on foodstuffs from Chernobyl-affected areas and travel to countries that suffered greater initial fall-out than the UK.

Combined interpretation of multiple geophysical techniques: an archaeological case study

NASA Astrophysics Data System (ADS)

Riedl, S.; Reichmann, S.; Tronicke, J.; Lück, E.

2009-04-01

In order to locate and ascertain the dimensions of an ancient orangery, we explored an area of about 70 m x 60 m in the Rheinsberg Palace Garden (Germany) with multiple geophysical techniques. The Rheinsberg Park, situated about 100 km northwest of Berlin, Germany, was established by the Prussian emperors in the 18th century. Due to redesign of the architecture and the landscaping during the past 300 years, buildings were dismantled and detailed knowledge about some original buildings got lost. We surveyed an area close to a gazebo where, after historical sources, an orangery was planned around the year 1740. However, today it is not clear to what extent this plan has been realized and if remains of this building are still buried in the subsurface. Applied geophysical techniques include magnetic gradiometry, frequency domain electromagnetic (FDEM) and direct current (DC) resistivity mapping as well as ground penetrating radar (GPR). To get an overview of the site, we performed FDEM electrical conductivity mapping using an EM38 instrument and magnetic gradiometry with caesium magnetometers. Both data sets were collected with an in- and crossline data point spacing of ca. 10 cm and 50 cm, respectively. DC resistivity surveying was performed using a pole-pole electrode configuration with an electrode spacing of 1.5 m and a spacing of 1.0 m between individual readings. A 3-D GPR survey was conducted using 200 MHz antennae and in- and crossline spacing of ca. 10 cm and 40 cm, respectively. A standard processing sequence including 3-D migration was applied. A combined interpretation of all collected data sets illustrates that the magnetic gradient and the EM38 conductivity maps is are dominated by anomalies from metallic water pipes from belonging to the irrigation system of the park. The DC resistivity map outlines a rectangular area which might indicate the extension of a former building south of the gazebo. The 3-D GPR data set provides further insights about subsurface structures and relevant geometries. From this data set, we interpret the depth and the extent of foundation and wall remains in the southern and central part of the site indicating the extent of the old orangery. This case study clearly illustrates the benefit of using multiple geophysical methods in archaeological studies. It further illustrates the advantage of 3-D GPR surveying at sites where anthropogenic disturbances (such as metallic pipes and other utilities) might limit the applicability of commonly applied mapping techniques such as magnetic gradiometry or EM38 conductivity mapping.

Dynamics of body burdens and doses due to internal irradiation from intakes of long-lived radionuclides by residents of Ozyorsk situated near Mayak PA.

PubMed

Suslova, K G; Romanov, S A; Efimov, A V; Sokolova, A B; Sneve, M; Smith, G

2015-12-01

This paper presents and discusses new autopsy results and other historic data from earlier autopsies and environmental monitoring linked to releases from the Mayak PA facilities in the Chelyabinsk oblast in the southern Urals. The focus is on residents of the town of Ozyorsk located near to Mayak PA and the dynamics of body burdens and radiation doses from inhalation of plutonium alpha and americium-241, and ingestion of strontium-90 and caesium-137. It is demonstrated that accumulation and exposure from these radionuclides was mainly due to unplanned releases in the 1950s and 60s. The mean content of plutonium alpha at the time of autopsy of people commencing residence in Ozyorsk from 1949 to 1959 was about 3.5 Bq, falling to 0.2 Bq in those arriving after 1990. A reducing trend was also seen for (241)Am. The highest (90)Sr content in Ozyorsk residents was measured in 1967. The (137)Cs body content of residents arriving in Ozyorsk at any time was in almost all cases below the limit of detection. The committed effective dose from internal exposure to these long-lived radionuclides which would have been accumulated in Ozyorsk residents if present from 1949 to 2013 is estimated to be 13 mSv. This dose is primarily attributed to intakes during 1949 to 1959 when the annual effective dose rate was approximately 1 mSv y(-1). The current value is about 0.1 mSv y(-1). This dose is about 20 times higher than the dose from global man-made fallout, which is about 0.005 mSv y(-1) at present, but much lower than that from natural background radiation, i.e. about 2 mSv y(-1). The experience gained from this work and continuing activities can contribute to the development of improved international guidance in legacy situations, particularly as regards the provision and use of monitoring data to test and thereby build confidence in prognostic models for radiation conditions and potential future exposures. The scope includes evidence for the rate of reduction in radionuclide concentrations in environmental media and in their bioavailability, resuspension of long-lived alpha radionuclides, uptake of (90)Sr and (137)Cs in the food-chain, and confirmation of cumulative uptake via autopsy and whole body counting measurements. Continuing investigations will thus support decisions on future planned releases and contribute to planning of remediation of other areas affected by historic releases.

OBITUARY: Leslie E Howlett, 1904 1992

NASA Astrophysics Data System (ADS)

Preston-Thomas, H.

1992-01-01

Dr L E Howlett of Ottawa (Canada), who died in his 88th year on 21 January 1992, was a member of the Comité International des Poids et Mesures (CIPM) from 1955 to 1968 and was President of the Comité Consultatif pour la Définition du Mètre (CCDM) from 1956. He was elected Vice-President of the CIPM in 1960 and President in 1964, and was made an honorary member following his retirement in 1968. After taking degrees from the universities of British Colombia, Toronto and McGill, Howlett joined Canada's National Research Council in 1931, remaining with that institution for virtually all of his working life. He initially set up, singlehandedly, an optics laboratory at the NRC, being joined by a technician in 1932. By the beginning of the war in September 1939 the laboratory had a staff of four, and this was the basis from which, under Howlett's direction, and with no prior optical production in the country, a Canadian optical industry was generated, with samples of a variety of optical instruments being completed by the end of April 1940, and many thousands of precision optical components being manufactured during the course of the war. Much of this precision optical work involved testing, measurement and calibration. Howlett's interests in such work were substantially enlarged when in 1948 he was put in charge, as Assistant Director, of applied research in the Division of Physics. This was, in effect, to be in charge of Canada's standards laboratory, and he then was naturally a candidate for membership of the CIPM. On the subsequent establishment of the Division of Applied Physics Howlett became its Director, a position he retained until his retirement. It was under Howlett's direction that Canada progressed from a state of having only commercial and surveying standards of very moderate precision to that of possessing a world-class standards laboratory. During the period of his membership of the CIPM, he was an enthusiastic proponent of the establishment of the ionizing radiation laboratory at the BIPM, and of the introduction of quantum metrology to the SI in the form of the krypton-86 definition of the metre, adopted in 1960 during his presidency of the CCDM, and the caesium-133 definition of the second in 1967. He was responsible for establishing Metrologia, under the auspices of the CIPM, being editor from its inception in 1965 until his retirement. For these, and for many other related services, Canada and the world measurement community will remember him and his work with gratitude.

Comparative study of A-site order in the lead-free bismuth titanates M{sub 1/2}Bi{sub 1/2}TiO{sub 3} (M=Li, Na, K, Rb, Cs, Ag, Tl) from first-principles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gröting, Melanie, E-mail: groeting@mm.tu-darmstadt.de; Albe, Karsten, E-mail: albe@mm.tu-darmstadt.de

2014-05-01

We investigate the possibility of enhancing chemical order in the relaxor ferroelectric Na{sub 1/2}Bi{sub 1/2}TiO{sub 3} upon substitution of Na{sup +} by other monovalent cations M{sup +} using total energy calculations based on density functional theory. All chemically available monovalent cations M{sup +}, which are Li, Na, Ag, K, Tl, Rb and Cs, are considered and an analysis of the structurally relaxed structures in terms of symmetry-adapted distortion modes is given in order to quantify the chemically induced structural distortions. We demonstrate that the replacement of Na{sup +} by other monovalent cations can hardly alter the tendency of chemical ordermore » with respect to Na{sub 1/2}Bi{sub 1/2}TiO{sub 3}. Only Tl{sub 1/2}Bi{sub 1/2}TiO{sub 3} and Ag{sub 1/2}Bi{sub 1/2}TiO{sub 3} show enhanced tendency for chemical ordering. Both heavy metals behave similar to the light alkali metals in terms of structural relaxations and relative stabilities of the ordered configurations. Although a comparison of the Goldschmidt factors of components (M TiO{sub 3}){sup −} reveals for Tl a value above the upper stability limit for perovskites, the additional lone-pair effect of Tl{sup +} stabilizes the ordered structure. - Graphical abstract: Amplitudes of chemically induced distortion modes in different ordered perovskites M{sub 1/2}Bi{sub 1/2}TiO{sub 3} and visualisation of atomic displacements associated with distortion mode X{sup +}{sub 1} in the 001-ordered compounds Li{sub 1/2}Bi{sub 1/2}TiO{sub 3} and Cs{sub 1/2}Bi{sub 1/2}TiO{sub 3}. Due to a substantial size mismatch between bismuth (green) and caesium (dark blue), incorporation of the latter leads to enhanced displacements of oxygen atoms (red) and suppresses displacements of titanium (silver) as compared to lithium (light blue) or other smaller monovalent cations. - Highlights: • Lead-free A-site mixed bismuth titanates M{sub 1/2}Bi{sub 1/2}TiO{sub 3} are studied by first-principles calculations. • Investigation of chemical ordering tendency for M=Li, Na, K, Rb, Cs, Ag, and Tl. • Group theoretical analysis of different ordered structures. • Ag and Tl compounds are the most promising candidates for study of chemical order dependent ferroelectric properties.« less

A comparative sensitivity analysis focused on wet deposition models for the Fukushima and Chernobyl atmospheric dispersion events

NASA Astrophysics Data System (ADS)

Quérel, Arnaud; Roustan, Yelva; Quélo, Denis; Bocquet, Marc; Winiarek, Victor

2014-05-01

In order to model the transport of radionuclides bound to atmospheric particles and the ground contamination at the synoptic scale, the wet deposition is a crucial point. Usually, the wet deposition is divided in two different mechanisms, the below-cloud scavenging (washout) and the in-cloud scavenging (rainout). Since the micro-physics of both deposition processes is not well known yet, the modeling of the wet deposition of particles at the synoptic scale is uncertain and difficult to validate. This leads to an abundance of wet deposition models, none of them being fully adequate. The existing models of particle scavenging can be distinguished by the nature and the number of physical parameters they rely on. For instance the scavenging coefficient variability can be determined only by the rainfall intensity or take into account the rainfall intensity and the particle size distribution. Beyond their intrinsic formulations, the deposition models are sensitive to the input data necessary to use them, cloud height for instance. Finally, the simulated ground deposition is more or less sensitive to the choices of the overall-models involved in the atmospheric transport of particles and the meteorology in general. For accidental atmospheric releases, the uncertainties linked to the source-term are for instance crucial, what justifies the use of different ones in the study. The Polyphemus air quality system is used to perform the simulations of the radioactive dispersion, considering Caesium-137 as particulate matter for the accidental releases from the Fukushima and Chernobyl nuclear power plants. In this study, two different approaches are used. In the first one, the influence of the different components taking part in the scavenging modeling are confronted separately (whether the scavenging models or the overall models). The second approach is a global sensitivity analysis computed both on the Chernobyl and Fukushima cases. It relies on simulations performed with several combinations of possible models that influence the wet deposition. These results are then compared to ground deposition observations, in order to determine the best model configurations, or at least to identify the worst ones, for each case. This study also enables the emphasis on sets of "good" or "bad" combinations common to both cases. The large number of models combinations implemented is also useful to investigate the robustness of reconstructed source terms, which are here determined on the basis of only one model configuration. Finally, the aim is to provide a better view of the limits of the currently available models.

Polonium-210 and Caesium-137 in lynx (Lynx lynx), wolverine (Gulo gulo) and wolves (Canis lupus).

PubMed

Gjelsvik, Runhild; Holm, Elis; Kålås, John Atle; Persson, Bertil; Asbrink, Jessica

2014-12-01

Wolves, lynx and wolverines are on the top of the food-chain in northern Scandinavia and Finland. (210)Po and (137)Cs have been analysed in samples of liver, kidney and muscle from 28 wolves from Sweden. In addition blood samples were taken from 27 wolves. In 9 of the wolves, samples of muscle, liver and blood were analysed for (210)Po. Samples of liver and muscle were collected from 16 lynx and 16 wolverines from Norway. The liver samples were analysed for (210)Po and (137)Cs. Only (137)Cs analyses were carried out for the muscle samples. The wolves were collected during the winter 2010 and 2011, while the samples for lynx and wolverines were all from 2011. The activity concentrations of (210)Po in wolves were higher for liver (range 20-523 Bq kg(-1) d.w.) and kidney (range 24-942 Bq kg(-1) d.w.) than muscle (range 1-43 Bq kg(-1) d.w.) and blood (range 2-54 Bq kg(-1) d.w.). Activity ratios, (210)Po/(210)Pb, in wolf samples of muscle, liver and blood were in the ranges 2-77, 9-56 and 2-54. Using a wet weight ratio of 3.8 the maximal absorbed dose from (210)Po to wolf liver was estimated to 3500 μGy per year. Compared to wolf, the ranges of (210)Po in liver samples were lower in lynx (range 22-211 Bq kg(-1) d.w.) and wolverine (range16-160 Bq kg(-1) d.w.). Concentration of (137)Cs in wolf samples of muscle, liver, kidney and blood were in the ranges 70-8410 Bq kg(-1) d.w., 36-4050 Bq kg(-1) d.w., 31-3453 Bq kg(-1) d.w. and 4-959 Bq kg(-1) d.w., respectively. (137)Cs in lynx muscle and liver samples were in the ranges 44-13393 Bq kg(-1) d.w. and 125-10260 Bq kg(-1) d.w. The corresponding values for (137)Cs in wolverine were 22-3405 Bq kg(-1) d.w. for liver and 53-4780 Bq kg(-1) d.w. for muscle. The maximal absorbed dose from (137)Cs to lynx was estimated to 3000 μGy per year. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exploring the potential for using 210Pbex measurements within a re-sampling approach to document recent changes in soil redistribution rates within a small catchment in southern Italy.

PubMed

Porto, Paolo; Walling, Desmond E; Cogliandro, Vanessa; Callegari, Giovanni

2016-11-01

In recent years, the fallout radionuclides caesium-137 ( 137 Cs) and unsupported lead-210 ( 210 Pb ex) have been successfully used to document rates of soil erosion in many areas of the world, as an alternative to conventional measurements. By virtue of their different half-lives, these two radionuclides are capable of providing information related to different time windows. 137 Cs measurements are commonly used to generate information on mean annual erosion rates over the past ca. 50-60 years, whereas 210 Pb ex measurements are able to provide information relating to a longer period of up to ca. 100 years. However, the time-integrated nature of the estimates of soil redistribution provided by 137 Cs and 210 Pb ex measurements can be seen as a limitation, particularly when viewed in the context of global change and interest in the response of soil redistribution rates to contemporary climate change and land use change. Re-sampling techniques used with these two fallout radionuclides potentially provide a basis for providing information on recent changes in soil redistribution rates. By virtue of the effectively continuous fallout input, of 210 Pb, the response of the 210 Pb ex inventory of a soil profile to changing soil redistribution rates and thus its potential for use with the re-sampling approach differs from that of 137 Cs. Its greater sensitivity to recent changes in soil redistribution rates suggests that 210 Pb ex may have advantages over 137 Cs for use in the re-sampling approach. The potential for using 210 Pb ex measurements in re-sampling studies is explored further in this contribution. Attention focuses on a small (1.38 ha) forested catchment in southern Italy. The catchment was originally sampled for 210 Pb ex measurements in 2001 and equivalent samples were collected from points very close to the original sampling points again in 2013. This made it possible to compare the estimates of mean annual erosion related to two different time windows. This comparison suggests that mean annual rates of net soil loss had increased during the period between the two sampling campaigns and that this increase was associated with a shift to an increased sediment delivery ratio. This change was consistent with independent information on likely changes in the sediment response of the study catchment provided by the available records of annual sediment yield and changes in the annual rainfall documented for the local area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Status of the Negative Ion Based Heating and Diagnostic Neutral Beams for ITER

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schunke, B.; Bora, D.; Hemsworth, R.

2009-03-12

The current baseline of ITER foresees 2 Heating Neutral Beam (HNB's) systems based on negative ion technology, each accelerating to 1 MeV 40 A of D{sup -} and capable of delivering 16.5 MW of D{sup 0} to the ITER plasma, with a 3rd HNB injector foreseen as an upgrade option. In addition a dedicated Diagnostic Neutral Beam (DNB) accelerating 60 A of H{sup -} to 100 keV will inject {approx_equal}15 A equivalent of H{sup 0} for charge exchange recombination spectroscopy and other diagnostics. Recently the RF driven negative ion source developed by IPP Garching has replaced the filamented ion sourcemore » as the reference ITER design. The RF source developed at IPP, which is approximately a quarter scale of the source needed for ITER, is expected to have reduced caesium consumption compared to the filamented arc driven ion source. The RF driven source has demonstrated adequate accelerated D{sup -} and H{sup -} current densities as well as long-pulse operation. It is foreseen that the HNB's and the DNB will use the same negative ion source. Experiments with a half ITER-size ion source are on-going at IPP and the operation of a full-scale ion source will be demonstrated, at full power and pulse length, in the dedicated Ion Source Test Bed (ISTF), which will be part of the Neutral Beam Test Facility (NBTF), in Padua, Italy. This facility will carry out the necessary R and D for the HNB's for ITER and demonstrate operation of the full-scale HNB beamline. An overview of the current status of the neutral beam (NB) systems and the chosen configuration will be given and the ongoing integration effort into the ITER plant will be highlighted. It will be demonstrated how installation and maintenance logistics have influenced the design, notably the top access scheme facilitating access for maintenance and installation. The impact of the ITER Design Review and recent design change requests (DCRs) will be briefly discussed, including start-up and commissioning issues. The low current hydrogen phase now envisaged for start-up imposed specific requirements for operating the HNB's at full beam power. It has been decided to address the shinethrough issue by installing wall armour protection, which increases the operational space in all scenarios. Other NB related issues identified by the Design Review process will be discussed and the possible changes to the ITER baseline indicated.« less

Sediment source fingerprinting to quantify fine sediment sources in forested catchments, Chile.

NASA Astrophysics Data System (ADS)

Schuller, P.; Walling, D. E.; Iroume, A.; Castillo, A.; Quilodran, C.

2012-04-01

A study to improve the understanding of the primary sediment sources and transfer pathways in catchments disturbed following forest plantation harvesting is being undertaken in South-Central Chile. The study focuses on two sets of paired experimental catchments (treatment and control), located about 400 km apart, with similar soil type but contrasting mean annual rainfall: Nacimiento (1,200 mm year-1) and Los Ulmos (2,500 mm year-1). Sediment source fingerprinting techniques are being used to document the primary fine sediment sources. In each catchment, three potential sediment sources were defined: clearcut slopes (Z1), forest roads (Z2) and the stream channel (Z3). In each catchment, multiple representative composite samples of the different potential source materials were collected before harvest operations from the upper 1 cm layer in Z1, Z2, and from the channel bank and bed for Z3. A time-integrating trap sampler installed in the discharge monitoring station constructed at the outlet of each catchment has been used to collect samples of the suspended sediment and these have been supplemented by sediment collected from the weir pools. Total suspended sediment load is been quantified in the monitoring stations using discharge records and integrated water sampling. Caesium-137 (137Cs), excess lead-210 (210Pbex) and other sediment properties are being used as fingerprints. After air-drying, oven-drying at 40°C and disaggregation, both the source material samples and the sediment samples collected in the discharge monitoring stations were sieved through a 63-μm sieve and the <63-μm fractions were used for subsequent analyses. For radionuclide assay, the samples were sealed in Petri dishes and after 4 weeks the mass activity density (activity concentration) of 137Cs and 210Pbex was determined by gamma analysis, using an ORTEC extended range Ge detector of 53% relative efficiency. The 137Cs and 210Pbex activity and organic carbon (Corg) concentration associated with potential source materials and the target sediment show that the two radionuclides used in combination with the Corg property provide effective source fingerprints. Additional work using a mixing model taking account of particle size effects is required to establish the relative contributions of the three sources to the fine sediment loads of the study catchments. This research is supported by the Chilean Government through FONDECYT Project 1090574 and by the IAEA through CRP D1.20.11 (Contract CHI-15531 and Technical Contract 15478) and the RLA 05/051 Project.

Cold Atom Optics on Ground and in Space

NASA Astrophysics Data System (ADS)

Rasel, E. M.

Microgravity is the ultimate laboratory environment for experiments in fundamental physics based on cold atoms. The talk will give a survey of recent activities on atomic quantum sensors and atom lasers. Inertial atomic quantum sensors are a promising and complementary technique for experiments in fundamental physics. Pioneering experiments at Yale [1,2] and Stanford [3] displayed recently the fascinating potential of matter-wave interferometers for precision measurements. The talk will present the status of a transportable matter-wave sensor under development at the Institut für Quantenoptik in Hannover: CASI. CASI stands for Cold Atom Sagnac Interferometer. The use of cold atoms makes it possible to realise compact devices with sensitivities competitive with classical state-of-the-art sensors. CASI's projected sensitivity is about 10-9 rad/ssurd Hz at the projection noise limit. The heart of our set-up will be a 15cm-long Mach-Zehnder interferometer formed by coherently splitting the atoms with Raman-type interactions. CASI is designed as a movable device, that it can be compared with other matter-wave sensors such as the cold caesium atom gyroscope at the BNM-SYRTE in Paris [4]. CASI is intimately connected with HYPER, an European initiative to send four atom interferometers in space hosted on a drag-free satellite. Main emphasis of the mission is placed on the mapping of the Earth's Lense-Thirring effect. Tests of the Equivalence Principle is under consideration as an alternative goal of high scientific value. HYPER was selected three years ago by the European Space Agency (ESA) as candidate for a future small-satellite mission within the next 10 to 15 years and is supported with detailed feasibility studies [5]. The latest status of the mission will be given. [1] T.L. Gustavson, A. Landragin, M.A, Kasevich, Rotation sensing with a dual atom-interferometer Sagnac gyroscope, Class. Quantum Grav. 17, 2385-2398 (2000) [2] J.M. McGuirk, G.T. Foster, J.B. Fixler, M.J. Snadden, M.A. Kasevich, Sensitive absolute-gravity gradiometry using atom interferometry, Phys. Rev. A 65, 033608-1 (2002) [3] A. Peters, K.Y. Chung, S. Chu, High-precision gravity measurements using atom interferometry, Metrologia 38, 25-61 (2001) [4] F. Yver-Leduc, P. Cheinet, J. Fils, A. Clairon, N. Dimarcq, D. Holleville, P. Bouyer, and A. Landragin. A. J. Opt. B : Quant. Semiclass. Opt. 5, S136 (2003) [5] http://sci.esa.int/home/hyper/index.cfm

The Study of Anti-/Pro-Oxidant, Lipophilic, Microbial and Spectroscopic Properties of New Alkali Metal Salts of 5-O-Caffeoylquinic Acid

PubMed Central

Kalinowska, Monika; Bajko, Ewelina; Matejczyk, Marzena; Kaczyński, Piotr; Łozowicka, Bożena; Lewandowski, Włodzimierz

2018-01-01

Lithium, sodium, potassium, rubidium and caesium salts of 5-O-caffeoylquinic acid (chlorogenic acid, 5-CQA) were synthesized and described by FT-IR (infrared spectroscopy), FT-Raman (Raman spectroscopy), UV (UV absorption spectroscopy), 1H (400.15 MHz), 13C (100.63 MHz) NMR (nuclear magnetic resonance spectroscopy). The quantum–chemical calculations at the B3LYP/6-311++G** level were done in order to obtain the optimal structures, IR spectra, NBO (natural bond orbital) atomic charges, HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) orbitals and chemical reactivity parameters for 5-CQA and Li, Na and K 5-CQAs (chlorogenates). The DPPH (α, α-diphenyl-β-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays were used for the preliminary estimation of the antioxidant properties of alkali metal chlorogenates and chlorogenic acid. In the DPPH assay the EC50 parameter were equal to 7.39 μM for 5-CQA and was in the range of 4.50–5.89 μM for salts. The FRAP values for two different concentrations (5 and 2.5 μM) of the studied compounds were respectively 114.22 and 72.53 μM Fe2+ for 5-CQA, whereas for salts they were 106.92–141.13 and 78.93–132.00 μM Fe2+. The 5-CQA and its alkali metal salts possess higher antioxidant properties than commonly applied antioxidants (BHA, BHT, l-ascorbic acid). The pro-oxidant action of these compounds on trolox oxidation was studied in the range of their concentration 0.05–0.35 μM. The lipophilicity (logkw) of chlorogenates and chlorogenic acid was determined by RP-HPLC (reverse phase—high performance liquid chromatography) using five different columns (C8, PHE (phenyl), CN (cyano), C18, IAM (immobilized artificial membrane)). The compounds were screened for their in vitro antibacterial activity against E. coli, Bacillus sp., Staphylococcus sp., Streptococcus pyogenes and antifungal activity against Candida sp. The 5-CQA possessed lower antibacterial (minimal inhibitory concentration, MIC = 7.06 mM) and antifungal (MIC = 14.11 mM) properties than its alkali metal salts (MIC values: 6.46–2.63 mM and 12.91–5.27mM, respectively). The synthesized chlorogenates possessed better antioxidant, lipophilic, antimicrobial as well as lower pro-oxidant properties than the ligand alone. Moreover, a systematic change of the activity of alkali metal salts along the series Li→Cs suggests that there are correlations between the studied biological properties. The type of metal cation in the carboxylate group of chlorogenate is crucial for the activity of studied compounds. PMID:29401704

Current radiological situation in areas of Ukraine contaminated by the Chernobyl accident: Part 1. Human dietary exposure to Caesium-137 and possible mitigation measures.

PubMed

Labunska, I; Kashparov, V; Levchuk, S; Santillo, D; Johnston, P; Polishchuk, S; Lazarev, N; Khomutinin, Y

2018-08-01

This study reports for the first time temporal trends for the period of 2011-2016 in 137 Cs content in cow's milk originating from private farms and households of 14 settlements located in the territories of the Rivne region, Ukraine. These areas are still radioactively contaminated as a result of the accident at the Chernobyl Nuclear Power Plant (ChNPP) in 1986. In 2016, the average 137 Cs activity concentration in milk exceeded the Ukrainian Permissible Level (PL) for adults of 100 Bq/l in samples from 6 settlements and the PL for children of 40 Bq/l in 8 settlements, reaching activity concentration of around 500 Bq/l in some samples. Estimated annual effective doses calculated utilizing two different methodologies were in the range of 1.4-2.6 mSv/year and 1.2-1.8 mSv/year, respectively. The estimated effective period of milk semi-purification (T 1/2 _ eff ) from 137 Cs in these settlements was in the range from 8 to 17 years. The estimated ecological period of milk semi-purification (T 1/2 _ eco ) from 137 Cs was in the range from 11 to 36 years. The optimization of the remedial actions strategy for investigated settlements exposed to an effective dose above 1 mSv/year (as estimated in 2016) has shown that a diversity of measures can decrease effective dose for a representative person to below 1 mSv/year. Such measures include application of Ferrocyn to cows, mineral fertilization of potato fields, information campaigns on consumption of wild mushrooms and other forestry products, and feeding pigs with uncontaminated fodder. The total costs of such measures are estimated to be about 71,000 Euro per year for the combined population (8336 inhabitants) of the six villages investigated in this study that showed the highest median residual 137 Cs activity concentrations in milk, with a subsequent decrease in cost in the future. This would result in an averted collective dose of 11 man-Sv, at an average cost of 6.5 kEuro/man-Sv averted. In the absence of governmental programs for implementation of necessary protective measures to reduce radiological risks to impacted populations, the exceedance of PL for the activity concentration of 137 Cs in cow's milk for adults of 100 Bq/l in the Chernobyl-affected areas of Ukraine could persist for many more years - until at least 2040. Copyright © 2018 Elsevier Ltd. All rights reserved.

External dose assessment in the Ukraine following the Chernobyl accident

NASA Astrophysics Data System (ADS)

Frazier, Remi Jordan Lesartre

While the physiological effects of radiation exposure have been well characterized in general, it remains unclear what the relationship is between large-scale radiological events and psychosocial behavior outcomes in individuals or populations. To investigate this, the National Science Foundation funded a research project in 2008 at the University of Colorado in collaboration with Colorado State University to expand the knowledge of complex interactions between radiation exposure, perception of risk, and psychosocial behavior outcomes by modeling outcomes for a representative sample of the population of the Ukraine which had been exposed to radiocontaminant materials released by the reactor accident at Chernobyl on 26 April 1986. In service of this project, a methodology (based substantially on previously published models specific to the Chernobyl disaster and the Ukrainian population) was developed for daily cumulative effective external dose and dose rate assessment for individuals in the Ukraine for as a result of the Chernobyl disaster. A software platform was designed and produced to estimate effective external dose and dose rate for individuals based on their age, occupation, and location of residence on each day between 26 April 1986 and 31 December 2009. A methodology was developed to transform published 137Cs soil deposition contour maps from the Comprehensive Atlas of Caesium Deposition on Europe after the Chernobyl Accident into a geospatial database to access these data as a radiological source term. Cumulative effective external dose and dose rate were computed for each individual in a 703-member cohort of Ukrainians randomly selected to be representative of the population of the country as a whole. Error was estimated for the resulting individual dose and dose rate values with Monte Carlo simulations. Distributions of input parameters for the dose assessment methodology were compared to computed dose and dose rate estimates to determine which parameters were driving the computed results. The mean external effective dose for all individuals in the cohort due to exposure to radiocontamination from the Chernobyl accident between 26 April 1986 and 31 December 2009 was found to be 1.2 mSv; the geometric mean was 0.84 mSv with a geometric standard deviation of 2.1. The mean value is well below the mean external effective dose expected due to typical background radiation (which in the United States over this time period would be 12.0 mSv). Sensitivity analysis suggests that the greatest driver of the distribution of individual dose estimates is lack of specific information about the daily behavior of each individual, specifically the portion of time each individual spent indoors (and shielded from radionuclides deposited on the soil) versus outdoors (and unshielded).

Analysis of whole-cell currents by patch clamp of guinea-pig myenteric neurones in intact ganglia

PubMed Central

Rugiero, François; Gola, Maurice; Kunze, Wolf A A; Reynaud, Jean-Claude; Furness, John B; Clerc, Nadine

2002-01-01

Whole-cell patch-clamp recordings taken from guinea-pig duodenal myenteric neurones within intact ganglia were used to determine the properties of S and AH neurones. Major currents that determine the states of AH neurones were identified and quantified. S neurones had resting potentials of −47 ± 6 mV and input resistances (Rin) of 713 ± 49 MΩ at voltages ranging from −90 to −40 mV. At more negative levels, activation of a time-independent, caesium-sensitive, inward-rectifier current (IKir) decreased Rin to 103 ± 10 MΩ. AH neurones had resting potentials of −57 ± 4 mV and Rin was 502 ± 27 MΩ. Rin fell to 194 ± 16 MΩ upon hyperpolarization. This decrease was attributable mainly to the activation of a cationic h current, Ih, and to IKir. Resting potential and Rin exhibited a low sensitivity to changes in [K+]o in both AH and S neurones. This indicates that both cells have a low background K+ permeability. The cationic current, Ih, contributed about 20 % to the resting conductance of AH neurones. It had a half-activation voltage of −72 ± 2 mV, and a voltage sensitivity of 8.2 ± 0.7 mV per e-fold change. Ih has relatively fast, voltage-dependent kinetics, with on and off time constants in the range of 50–350 ms. AH neurones had a previously undescribed, low threshold, slowly inactivating, sodium-dependent current that was poorly sensitive to TTX. In AH neurones, the post-action-potential slow hyperpolarizing current, IAHP, displayed large variation from cell to cell. IAHP appeared to be highly Ca2+ sensitive, since its activation with either membrane depolarization or caffeine (1 mm) was not prevented by perfusing the cell with 10 mm BAPTA. We determined the identity of the Ca2+ channels linked to IAHP. Action potentials of AH neurones that were elongated by TEA (10 mm) were similarly shortened and IAHP was suppressed with each of the three Ω-conotoxins GVIA, MVIIA and MVIIC (0.3–0.5 μm), but not with Ω-agatoxin IVA (0.2 μm). There was no additivity between the effects of the three conotoxins, which indicates the presence of N- but not of P/Q-type Ca2+ channels. A residual Ca2+ current, resistant to all toxins, but blocked by 0.5 mm Cd2+, could not generate IAHP. This patch-clamp study, performed on intact ganglia, demonstrates that the AH neurones of the guinea-pig duodenum are under the control of four major currents, IAHP, Ih, an N-type Ca2+ current and a slowly inactivating Na+ current. PMID:11790812

Distribution of Technetium-99 in sub-tidal sediments of the Irish Sea

NASA Astrophysics Data System (ADS)

McCubbin, David; Leonard, Kinson S.; McDonald, Paul; Bonfield, Rachel; Boust, Dominique

2006-03-01

To date, relatively little attention has been given to the accumulation of 99Tc discharged from Sellafield in the subtidal sediments of the Irish Sea. The potential implications for secondary seafood contamination from contaminated sediment has driven the UK Food Standards Agency to commission further research into this pathway. The work reported here reviews existing data and provides new measurements of 99Tc specific activity in surface and sub-surface sediments of the Irish Sea, together with environmental Kd values. The results are used to assess the spatial and temporal evolution of 99Tc in the seabed after 8 years of enhanced Sellafield discharges (between 1994 and 2002), of the aforementioned radionuclide. The information is discussed with reference to other studies, in an attempt to infer the processes controlling 99Tc uptake and release from seabed sediments. The average environmental Kd value for 99Tc in the Irish Sea (1.9×10 3) was more than an order of magnitude greater than the presently recommended value of 10 2 [IAEA, 2004. Sediment distribution coefficients and concentration factors for biota in the marine environment. Technical Report Series No. 422, IAEA, Vienna]. Comparison with results from laboratory studies indicates that the observed distribution may represent metastable binding rather than thermodynamic equilibrium. Activities in surface sediments decreased with increasing distance from Sellafield but were also dependent upon the nature of the underlying substrate, being greater on muddy material. Preliminary measurements of grain-size distribution indicated that the observed variation in activities was probably not due to surface area effects. There is an emerging body of evidence from other studies that indicate the differences were most likely due to variations in redox regimes between the different substrates. Vertical profiles were significantly irregular, probably due to the effects of variable sediment mixing processes. Comparison of profiles, close to the Sellafield pipeline, with a core taken over 20 years earlier (pre-EARP) indicated that the increase in the cumulative Sellafield discharge and redissolution from surficial sediment were required to explain the temporal variation. Since the surveys reported here were completed, substantial progress has been made in reducing 99Tc discharges from Sellafield. Assuming that the rate and extent of 99Tc remobilisation follows a similar pattern to that previously observed for caesium ( 137Cs), then the half-time for redissolution of 99Tc bound to sedimentary material in the Irish Sea is likely to be of the order of several tens of years. It is probable that small but nevertheless measurable 99Tc contamination of local seafood will persist for several decades, due to this secondary source.

Radiocaesium soil-to-wood transfer in commercial willow short rotation coppice on contaminated farm land.

PubMed

Gommers, A; Gäfvert, T; Smolders, E; Merckx, R; Vandenhove, H

2005-01-01

The feasibility of willow short rotation coppice (SRC) for energy production as a revaluation tool for severely radiocaesium-contaminated land was studied. The effects of crop age, clone and soil type on the radiocaesium levels in the wood were assessed following sampling in 14 existing willow SRC fields, planted on radiocaesium-contaminated land in Sweden following Chernobyl deposition. There was only one plot where willow stands of different maturity (R6S2 and R5S4: R, root age and S, shoot age) and clone (Rapp and L78183 both of age category R5S4) were sampled and no significant differences were found. The soils differed among others in clay fraction (3-34%), radiocaesium interception potential (515-6884 meq kg(-1)), soil solution K (0.09-0.95 mM), exchangeable K (0.58-5.77 meq kg(-1)) and cation exchange capacity (31-250 meq kg(-1)). The soil-to-wood transfer factor (TF) of radiocaesium differed significantly between soil types. The TF recorded was generally small (0.00086-0.016 kg kg(-1)), except for willows established on sandy soil (0.19-0.46 kg kg(-1)). Apart from the weak yet significant exponential correlation between the Cs-TF and the solid/liquid distribution coefficient (R2 = 0.54) or the radiocaesium interception potential, RIP (R2 = 0.66), no single significant correlations between soil characteristics and TF were found. The wood-soil solution 137Cs concentration factor (CF) was significantly related to the potassium concentration in the soil solution. A different relation was, however, found between the sandy Trödje soils (CF = 1078.8 x m(K)(-1.83), R2 = 0.99) and the other soils (CF = 35.75 x m(K)(-0.61), R2 =0.61). Differences in the ageing rate of radiocaesium in the soil (hypothesised fraction of bioavailable caesium subjected to fast ageing for Trödje soils only 1% compared to other soils), exchangeable soil K (0.8-1.8 meq kg(-1) for Trödje soils and 1.5-5.8 meq kg(-1) for the other soils) and the ammonium concentration in the soil solution (0.09-0.31 mM NH4+ for the Trödje soils compared to 0.003-0.11 mM NH4+ for the other soils) are put forward as potential factors explaining the higher CF and TF observed for the Trödje soils. Though from the dataset available it was not possible to unequivocally predict the Cs-soil-to-wood-transfer, the generally low TFs observed point to the particular suitability for establishment of SRC on radiocaesium-contaminated land.

Magnetic signatures of the orogenic crust of the Patagonian Andes with implication for planetary exploration

NASA Astrophysics Data System (ADS)

Díaz Michelena, Marina; Kilian, Rolf

2015-11-01

The Patagonian Andes represent a good scenario of study because they have outcrops of diverse plutonic rocks representative of an orogenic crust on Earth and other planets. Furthermore, metamorphic surface rocks provide a window into deeper crustal lithologies. In such remote areas, satellite and aerial magnetic surveys could provide important geological information concerning exposed and not exposed rocks, but they integrate the magnetic anomalies in areas of kilometres. For the southernmost Andes long wavelength satellite data show clear positive magnetic anomalies (>+100 nT) for the Patagonian Batholith (PB), similar as parts of the older martian crust. This integrated signal covers regions with different ages and cooling histories during magnetic reversals apart from the variability of the rocks. To investigate the complex interplay of distinct magnetic signatures at short scale, we have analysed local magnetic anomalies across this orogen at representative sites by decimeter-scale magnetic ground surveys. As expected, the investigated sites have positive and negative local anomalies. They are related to surface and subsurface rocks, and their different formation and alternation processes including geomagnetic inversions, distinct Curie depths of the magnetic carriers, intracrustal deformation among other factors. Whole rock chemistry (ranging from 45 to >80 wt.% SiO2 and from 1 to 18 wt.% FeOtot.), magnetic characteristics (susceptibilities, magnetic remanence and Königsberger ratios) as well as the composition and texture of the magnetic carriers have been investigated for representative rocks. Rocks of an ultramafic to granodioritic intrusive suite of the western and central PB contain titanomagnetite as major magnetic carrier. Individual magnetic signatures of these plutonic rocks reflect their single versus multidomain status, complex exolution processes with ilmenite lamella formations and the stoichiometric proportions of Cr, Fe and Ti in the oxides. At the eastern margin of the PB the investigated plutons and mafic dykes have been emplaced and equilibrated at 4-6 km depth. They do not contain magnetite but include variable amounts of ferrimagnetic monoclinic C4 pyrrhotite, which was formed along fractures zones by a hydrothermal gold-bearing mineralisation. The intensity of their positive magnetic anomalies (up to +220 nT) is well correlated with the amount of pyrrhotite (1-4 vol.%). In all cases, high resolution ground surveys variations of the magnetic signature down to 20 nT could be used to clearly distinguish different rock types on a decimeter scale. Vector magnetometer MOURA designed for martian exploration was successfully used for these surveys and provides results comparable to a commonly used caesium scalar magnetometer. This is important for near future ground surveys on Mars and the Moon.

Understanding Polycyclic Aromatic Hydrocarbon transfers at the catchment scale combining chemical and fallout radionuclide analyses

NASA Astrophysics Data System (ADS)

Gateuille, D.; Evrard, O.; Lefevre, I.; Moreau-Guigon, E.; Alliot, F.; Chevreuil, M.; Mouchel, J.-M.

2012-04-01

Reducing environmental contamination constitutes a major challenge for industrialized countries. Furthermore, in the European Union, Water Framework Directive (WFD; Directive 2000/60/EC) requires that the member state water bodies reach good ecological and chemical status by 2015. Polycyclic Aromatic Hydrocarbons (PAHs) are a group of persistent organic pollutants considered as priority pollutants because of their mutagenic and carcinogenic properties. They are mostly emitted by human activities such as household heating or road traffic. Although emissions have decreased during the last decades, a large amount of PAHs have been released into the atmosphere for the last two centuries. In recent years, studies dealing with PAHs have grown in number but most of them were restricted to the measurement of PAHs concentrations in the different compartments of the environment (air, soil, sediment, water, etc.). In this context, there remains a lack of knowledge about the transfers and, consequently, about the persistence of these compounds in the environment. This question is particularly acute in the Seine River basin where very high concentrations in PAHs are reported in sediment, thereby compromising the achievement of the good chemical status required by WFD. Our study aims to quantify PAHs transfers at the catchment scale by combining chemical analysis with gamma spectrometry. Atmospheric fallout, soil, river water and sediment samples were collected in two upstream sub-catchments of the Seine River basin during one year. Chemical analyses, restricted to 15 of the 16 PAHs selected by the US Environmental Protection Agency (USEPA), were carried out to determine PAHs concentrations in all samples. Contamination spectra were used to outline the potential origin of pollution. Measurement of fallout radionuclides (Beryllium-7, Lead-210, Caesium-137) in both rainfall and river sediment provided a way to discriminate between freshly eroded sediment vs. material that deposited on the riverbed. These data are crucial to estimate PAH residence time in the Seine River basin and to know if current river pollution is resulting from recent emissions or from the persistence of former sources. Results show that spectra of contaminants in sediment are similar in most of the sampling sites. This underlines the possibility of a common primary source. Moreover, local variations of atmospheric PAHs fallout are poorly significant within the subcatchments, even though concentrations greatly vary in sediment. This underlines the presence of local secondary sources where accumulation of atmospheric fallout is more important but their deposition ways still remain to determine. At other sites, impact of urbanized area is more likely to be the source of light HAPs in sediment. Measurements in soils show larger concentrations in forest than in grassland or in cropland. This can be explained by a bigger affinity of PAHs for the soils richer in Organic matter (OM) and lower erodibility of woodland.

FOREWORD: Fifty years of atomic time-keeping: 1955 to 2005

NASA Astrophysics Data System (ADS)

Quinn, Terry

2005-06-01

The year 2005 is the centenary of Einstein's four famous papers that were published in 1905. This anniversary is being widely celebrated all over the world and, indeed, 2005 has been dubbed World Year of Physics. The year 2005, however, also marks the fiftieth anniversary of the first operation of Essen and Parry's caesium beam atomic frequency standard at the NPL in May 1955. While Einstein's papers signalled a revolution in physics and in our understanding of the natural world, the first atomic clock signalled a revolution in time-keeping that has become, among other things, one of the most powerful tools in pushing back the frontiers of Einstein's theories of special and general relativity. The atomic clock has also had consequences for navigation comparable to those brought about by Harrison's mechanical clocks almost exactly two hundred years before. Harrison's H3 was completed in 1757 and H4 in 1759. The atomic clock, and the creation of an atomic time scale that quickly followed, led ten years later to the adoption of an atomic definition for the SI second in Resolution 1 of the 13th General Conference on Weights and Measures, 1967/68. This marked the end of time-keeping based on the movements of the heavenly bodies that had beaten the rhythm of the days and the seasons since the dawn of human civilization. Fifty years on is a good occasion to look back, to look forward and at the same time to examine where we are today, in terms of measuring time. While we still arrange for our atomic clocks to show noon when the sun is overhead on the Greenwich meridian, everything else has changed in the fifty years since 1955. In this special issue of Metrologia the reader will find articles on the development of the atomic clock, its theory and practice, how the first atomic time scale was devised and formally introduced and how we maintain atomic time today, as well as articles looking forward to even more accurate clocks and time scales. Included also are articles on the commercial development of atomic clocks of various types and on some of their applications. At the beginning there is a deliberate emphasis on the history of the introduction of atomic time, including the technical problems to be resolved and the personalities involved. You will see that it includes one article based on notes left by Louis Essen himself, for which we are most grateful to his son, Mr Ray Essen, for permission to use them and to Dale Henderson of the NPL, who arranged them for publication here. I hope that this issue will stand as a reference for years to come and I am most grateful to all those who have contributed. I also wish to thank most particularly Norman Ramsey, whose name is indelibly associated with atomic clocks, for having contributed the first article to this special issue.

Downstream mixing of sediment and tracers in agricultural catchments: Evidence of changing sediment sources and fluvial processes?

NASA Astrophysics Data System (ADS)

Ralph, Timothy; Wethered, Adam; Smith, Hugh; Heijnis, Henk

2014-05-01

Land clearance, soil tillage and grazing in agricultural catchments have liberated sediment and altered hydrological connectivity between hillslopes and channels, leading to increased sediment availability, mobilisation and delivery to rivers. The type and amount of sediment supplied to rivers is critical for fluvial geomorphology and aquatic ecosystem health. Contemporary sediment dynamics are routinely investigated using environmental radionuclides such as caesium-137 (Cs-137) and excess lead-210 (Pb-210ex), which can provide information regarding sediment source types and fluvial processes if sediment sources can be distinguished from one another and mixing models applied to representative samples. However, downstream transport, mixing and dilution of radionuclide-labelled sediment (especially from sources with low initial concentrations) can obliterate the tracer signal; sometimes before anything of geomorphological importance happens in the catchment. Can these findings be used as evidence of sediment source variations and fluvial processes when the limits of detection (of Cs-137 in particular) are being exceeded so rapidly downstream? Sediment sources and downstream sediment dynamics were investigated in Coolbaggie Creek, a major supplier of sediment to the Macquarie River in an agricultural catchment with temperate to semi-arid climate in Australia. Radionuclides were used to discriminate between the <63 micron fraction of sediment sources including forested topsoils (Cs-137 11.28 +/- 0.75 Bq/kg; Pb-210ex 181.87 +/- 20.00 Bq/kg), agricultural topsoils (Cs-137 3.21 +/- 0.26 Bq/kg; Pb-210ex 29.59 +/- 10.94 Bq/kg) and sub-soils from channel banks and gullies (Cs-137 1.45 +/- 0.47 Bq/kg; Pb-210ex 4.67 +/- 1.93 Bq/kg). Within the trunk stream, suspended sediment, organic matter and Cs-137 and Pb-210ex concentrations declined downstream. Results from a mixing model suggest that agricultural topsoils account for 95% of fine sediment entering the channel in the upper reach (<10 km long), while sub-soils account for 90 to 100% of sediment entering and being transported in the remaining ~50 km of the system. This shift in dominant sediment source material coincided with a large increase in channel cross sectional area (~20 to >200 m2) downstream, with channel expansion and gullies contributing fine sediment to the system. A lack of topsoil being supplied to the channel suggests minimal lateral connectivity between the catchment and the trunk stream in all areas apart from the upper catchment. The enlargement and entrenchment of the channel downstream has also resulted in lateral disconnection between the channel and floodplain. In this case, a rapid reduction in radionuclide concentrations downstream does coincide with hydrogeomorphic changes, supporting their use for studying short-term sediment dynamics. These findings highlight the importance of understanding hydrogeomorphic processes and connectivity when interpreting sediment source and tracer data.

Geomorphic and ecological effects of Hurricanes Katrina and Rita on coastal Louisiana marsh communities

USGS Publications Warehouse

Piazza, Sarai C.; Steyer, Gregory D.; Cretini, Kari F.; Sasser, Charles E.; Visser, Jenneke M.; Holm, Guerry O.; Sharp, Leigh A.; Evers, D. Elaine; Meriwether, John R.

2011-01-01

Hurricanes Katrina and Rita made landfall in 2005, subjecting the coastal marsh communities of Louisiana to various degrees of exposure. We collected data after the storms at 30 sites within fresh (12), brackish/intermediate (12), and saline (6) marshes to document the effects of saltwater storm surge and sedimentation on marsh community dynamics. The 30 sites were comprised of 15 pairs. Most pairs contained one site where data collection occurred historically (that is, prestorms) and one Coastwide Reference Monitoring System site. Data were collected from spring 2006 to fall 2007 on vegetative species composition, percentage of vegetation cover, aboveground and belowground biomass, and canopy reflectance, along with discrete porewater salinity, hourly surface-water salinity, and water level. Where available, historical data acquired before Hurricanes Katrina and Rita were used to compare conditions and changes in ecological trajectories before and after the hurricanes. Sites experiencing direct and indirect hurricane influences (referred to in this report as levels of influence) were also identified, and the effects of hurricane influence were tested on vegetation and porewater data. Within fresh marshes, porewater salinity was greater in directly impacted areas, and this heightened salinity was reflected in decreased aboveground and belowground biomass and increased cover of disturbance species in the directly impacted sites. At the brackish/intermediate marsh sites, vegetation variables and porewater salinity were similar in directly and indirectly impacted areas, but porewater salinity was higher than expected throughout the study. Interestingly, directly impacted saline marsh sites had lower porewater salinity than indirectly impacted sites, but aboveground biomass was greater at the directly impacted sites. Because of the variable and site-specific nature of hurricane influences, we present case studies to help define postdisturbance baseline conditions in fresh, brackish/ intermediate, and saline marshes. In fresh marshes, the mechanism of hurricane influence varied across the landscape. In the western region, saltwater storm surge inundated freshwater marshes and remained for weeks, effectively causing damage that reset the vegetation community. This is in contrast to the direct physical disturbance of the storm surge in the eastern region, which flipped and relocated marsh mats, thereby stressing the vegetation communities and providing an opportunity for disturbance species to colonize. In the brackish/intermediate marsh, disturbance species took advantage of the opportunity provided by shifting species composition caused by physical and saltwater-induced perturbations, although this shift is likely to be short lived. Saline marsh sites were not negatively impacted to a severe degree by the hurricanes. Species composition of vegetation in saline marshes was not affected, and sediment deposition appeared to increase vegetative productivity. The coastal landscape of Louisiana is experiencing high rates of land loss resulting from natural and anthropogenic causes and is experiencing subsidence rates greater than 10.0 millimeters per year (mm yr-1); therefore, it is important to understand how hurricanes influence sedimentation and soil properties. We document long-term vertical accretion rates and accumulation rates of organic matter, bulk density, carbon and nitrogen. Analyses using caesium-137 to calculate long-term vertical accretion rates suggest that accretion under impounded conditions is less than in nonimpounded conditions in the brackish marsh of the chenier plain. Our data also support previous studies indicating that accumulation rates of organic matter explain much of the variability associated with vertical accretion in brackish/intermediate and saline marshes. In fresh marshes, more of the variability associated with vertical accretion was explained by mineral accumulation than in the other mars

Human metabolism and ecological transfer of radioactive caesium: Comparative studies of Chernobyl debris and nuclear weapons fallout, in Southern Sweden and in Bryansk, Russia

NASA Astrophysics Data System (ADS)

Raaf, Christopher Leopold

The whole-body content of radiocaesium was measured in a South-Swedish urban group of people residing in the city of Lund (55.7°N, 13.2°E) between 1960 and 1994. The results from the survey have been analysed in order to estimate the ecological half-time, Teff,eco, of fallout radiocaesium and the aggregate transfer from ground deposition to man in the region. After 1987, the biological half-times, Ts, of 137Cs and 40K in man were also determined in the reference group through whole-body content measurements in combination with 24-hour urine sampling. Relationships between 24-hour urinary excretion and body burden of 137Cs in the group together with data from the literature were then applied to urine samples collected in 1994 and 1995 from adult subjects living in the highly contaminated region of Bryansk, Russia, in order to estimate their average body burden of 137Cs. The equivalent biological half-time for 137Cs in females of the Lund reference group was, on average (+/-1 WSE), 66 +/- 3 d, which agrees with other findings, whereas the value for the males, 81 +/- 4 d, was, on average, significantly lower than what is found in the literature. This is partly explained by the elevated mean age and relatively low mean body muscle mass of the males investigated in the group during the post-Chernobyl study period. The effective ecological half-time for 137Cs from Chernobyl was found to be 1.8 +/- 0.2 y. The aggregate transfer of 137Cs from deposition to mean activity concentration in man was estimated to be 1.7 Bq kg-1/kBq m-2. These vales may be compared with an effective ecological half-time of 1.3 years found in the reference group in the 1960s, and an aggregate transfer factor of 9.8 Bq kg-1/kBq m-2. The average committed effective dose from ingested 137Cs Chernobyl fallout in the study group was estimated to be 0.02 mSv and from the nuclear weapons fallout to 0.20 mSv. The estimates of whole-body content of 137Cs in the Russian subjects obtained through creatinine normalisation of the 137Cs content in urine were, on average, a factor of 2 higher than estimates obtained through a potassium normalisation procedure; 55 +/- 8 (1 SE) kBq for creatinine and 29 +/- 4 (1 SE) kBq for potassium normalisation in the year 1994. This was due to a significant difference in the relationship between the urinary potassium and creatinine concentration between the Swedish and Russian group. The elevated potassium concentration found in the rural Russian subjects indicated a higher dietary intake of potassium, which greatly influences the accuracy and applicability of the potassium normalisation method when estimating body burden of 137Cs through urine assay. It is therefore recommended not to use the potassium normalisation procedure in cases where the daily intake of potassium is unknown. The estimated body burden of 137Cs in the Bryansk group in 1994 corresponds to a contribution to the estimated annual effective dose of 1.8 mSv y-1, which is approximately 200 times greater than the average annual dose received from ingested 137Cs by the subjects of the Lund reference group during the period 1987-1994.

Caesium-137 soil-to-plant transfer for representative agricultural crops of monocotyledonous and dicotyledonous plants in post-Chernobyl steppe landscape

NASA Astrophysics Data System (ADS)

Paramonova, Tatiana; Komissarova, Olga; Turykin, Leonid; Kuzmenkova, Natalia; Belyaev, Vladimir

2016-04-01

The accident at the Chernobyl nuclear power plant in 1986 had a large-scale action on more than 2.3 million hectares agricultural lands in Russia. The area of radioactively contaminated chernozems of semi-arid steppe zone with initial levels of Cs-137 185-555 kBq/m2 in Tula region received the name "Plavsky radioactive hotspot". Nowadays, after the first half-life period of Cs-137 arable chernozems of the region are still polluted with 3-6-fold excess above the radioactive safety standard (126-228 kBq/m2). Therefore, qualitative and quantitative characteristics of Cs-137 soil-to-plant transfer are currently a central problem for land use on the territory. The purpose of the present study was revealing the biological features of Cs-137 root uptake from contaminated arable chernozems by different agricultural crops. The components of a grass mixture growing at the central part of Plavsky radioactive hotspot with typical dicotyledonous and monocotyledonous plants - galega (Galega orientalis, Fabaceae family) and bromegrass (Bromus inermis, Gramineae family) respectively - were selected for the investigation, that was conducted during the period of harvesting in 2015. An important point was that the other factors influenced on Cs-137 soil-to-plant transfer - the level of soil pollution, soil properties, climatic conditions, vegetative phase, etc. - were equal. So, biological features of Cs-137 root uptake could be estimated the most credible manner. As a whole, general discrimination of Cs-137 root uptake was clearly shown for both agricultural crops. Whereas Cs-137 activity in rhizosphere 30-cm layer of arable chernozem was 371±74 Bq/kg (140±32 kBq/m2), Cs-137 activities in plant biomass were one-two orders of magnitude less, and transfer factor (TF) values (the ratio of the Cs-137 activities in vegetation and in soil) not exceeded 0.11. At the same time bioavailability of Cs-137 for bromegrass was significantly higher than for galega: TFs in total biomass of the crops were 0.11 and 0.01 correspondingly. But the most dramatic difference between the investigated crops was connected with peculiarities of Cs-137 distribution within above- and belowground parts of biomass. While TF in aboveground fraction of galega (0.02) was slightly higher than in belowground fraction (0.01), the bulk of Cs-137 in bromegrass was detected not in shoots but in roots (TFs 0.05 and 0.11 correspondingly). More extensive examination of Cs-137 behavior in "soil-plant" systems of agricultural crops in the area of Plavsky radioactive hotspot has revealed that all investigated dicotyledonous plants with taproot system (potatoes, soya, amaranth, rape) accumulated 71±14% of Cs-137 inventories in aboveground biomass, whereas monocotyledonous plants with fibrous root system (wheat, barley, maize, cereal pasture species) deposited 94±5% of Cs-137 supplies in their belowground biomass. Thus, the first had effective biological root barrier protecting vegetation from general Cs-137 incorporation into biomass, but relatively active radionuclide translocation into shoots, while the second were characterized by slight rhizofiltration property and occurrence an additional barrier between roots and shoots determining only moderate radionuclide translocation into aboveground biomass. Such biological features should be taken into account in deciding on rehabilitation strategy of radioactively contaminated lands. The study was conducted with the support from the Russian Foundation for Basic Research (project no. 14-05-00903).

High resolution analysis of northern Patagonia lake sediments

NASA Astrophysics Data System (ADS)

Jarvis, S. W.; Croudace, I. W.; Langdon, P. G.; Rindby, A.

2009-04-01

Sediment cores covering the period from the last glacial maximum through the Holocene to the present have been collected from sites in the Chacubuco valley, southern Chile (around 47°08'S, 72°25'W, to the east of the North Patagonian Icecap). Cores were taken from five lakes and one recently dried lake bed. Short cores (0.2 to 0.5m), covering approximately the last two hundred years, were taken from all the lakes. Additionally, long sequences were obtained from one of the lakes and from the dried lake bed, the latter sequence extending back to the last glacial maximum as indicated by thick clay at the base. Each of the lakes are small-medium sized and are open systems situated at 300-1000m above sea level. The shorter cores comprise predominantly clastic gyttja but show a number of distinct changes in colour and chemical composition that suggest major environmental changes over the period of sediment accumulation. This is also reflected in variations in the loss on ignition of samples from the cores and in elemental profiles produced by scanning the cores with the Itrax micro-XRF corescanner at 200μm resolution. The long sequence from the dried lake bed has very low organic content glacial clay at the base, interpreted as last glacial maximum basal clay following determination in the field that this layer exceeded 2m in thickness. Similar sediments occur within a stratigraphically discrete section of approximately 14cm and may relate to a stadial event. The latter section also shows a drop in organic content and appears to be glacial clay incorporating some coarse sandy components indicative of detrital input from the catchment. The second long sequence, from a carbonate lake, includes two mineral layers indicating increased detrital input from the catchment. The deeper and thicker of these layers appears similar to the 14cm layer in the first long sequence, while the upper layer comprises a fine grain size indicative of rock flour and hence also of glacial activity in the catchment. Variation of elemental composition of these ‘glacial' layers is also clear from the Itrax data. It therefore appears that there have been significant reglaciation events in the catchment since the last glacial maximum. Many cores contain tephra layers, identified both visually and from the Itrax scans. Some of these have been confirmed as volcanic ash from the 1991 eruption of Mt Hudson, which at 45°54'S, 72°58'W is the southern-most volcano in the Chilean Andes and only 140km from the study area. Further work is underway to confirm and identify the source and age of other suspected tephra layers. Sediment accumulation rates in the upper parts of the cores are of the order of 1mm/yr (as determined by lead-210, caesium-137 dating and the 1991 Hudson tephra). Given XRF scan resolutions of up to 200μm there is thus the potential for investigation of sub-annual variability. Funding has been obtained to determine carbon-14 dates for the lower parts of the longer cores. The reproducibility and accuracy of the Itrax data has been validated using conventional WD-XRF spectrometry and the work presented will also include geochemical interpretation of the XRF data and comparison with recorded and proxy-inferred climate data for the region.

Effect of tree thinning and litter removal on the radiocesium (Cs-134, 137) discharge rates in the Kawauchi forest plantation (Fukushima Prefecture, northern Japan)

NASA Astrophysics Data System (ADS)

López-Vicente, Manuel; Onda, Yuichi; Takahashi, Junko; Kato, Hiroaki; Hisadome, Keigo

2016-04-01

On 11 March 2011 a 9.0 earthquake and the resulting tsunami occurred in central-eastern Japan triggering, one day after, the Fukushima Dai-ichi nuclear power plant (DNPP) accident. Despite the bulk of radionuclides (ca. 80%) were transported offshore and out over the Pacific Ocean, significant wet and dry deposits of those radionuclides occurred mainly in the Fukushima Prefecture and in a minor way in the Miyagi, Tochigi, Gunma and Ibaraki Prefectures. As a consequence and among other radionuclides, a total of 511,000 TBq of I-131, 13,500 TBq of Cs-134 and 13,600 TBq of Cs-137 were released into the atmosphere and the ocean, contaminating cultivated soils, rivers, settlements and forested areas. This accident caused severe environmental and economic damages. Several decontamination practices have done, including tree thinning and litter removal within the forests and tree plantations. In this study we analysed the effect of eight different management practices on the radiocesium (Cs-134 and Cs-137) discharge rates during 20 months (May'2013 - Dec'2014) in a Japanese cedar (Cryptomeria japonica) plantation (stand age of 57 years), located in a hillslope near the Kawauchi village, Fukushima Prefecture, northern Japan. This study area (37⁰ 20' 04" N, 140⁰ 53' 13.5" E) is located 16 km southwestern from the DNPP and within the evacuation area. The soils are Andosols. Ten runoff plots (5 x 2 meters) were installed and measurements started on May 2013. Two plots remained without any treatment as control plots and the other eight plots represented the following management practices: Mng1) Litter removal + clear-cutting (no sheet); Mng2) Litter removal + clear-cutting (no sheet); Mng3) Litter removal + clear-cutting (no sheet); Mng4) Litter removal; Mng5) Thinning (logged area); Mng6) Thinning (under remnant trees); Mng7) Litter removal + thinning (logged area); Mng8) Litter removal + thinning (under remnant trees). Each plot had a gauging station and sediment samples were collected every three weeks. Litter removal and tree thinning were done twice. The minimum of ground and vegetation coverages occurred in May and June 2013 and between February and April 2014. The maximum coverages appeared in September-October 2013 and between July and September 2014. The radioactivities of Cs-134 and Cs-137 were determined in the soil and litter fractions by gamma-ray spectrometry. Emissions were measured using a high purity n-type Ge coaxial detector coupled to an amplified and multichannel analyser at the CRiED laboratory of the University of Tsukuba. The activity concentration (Bq / kg) of Cs-134 and Cs-137 were calculated as well as the inventory (Bq / m2) and daily inventory (Bq / m2 day) of Cs-137. A total of 70 correlations were analysed: between the dry weight of the leaf and soil and the corresponding activity of Cs-134 and Cs-137 as well as between the total movement and total daily movement of leaf and soil and the inventory and daily inventory of Cs-137. The amount of soil and caesium movement in the experimental slopes was considerably decreased in the year 2014 than in 2013 due to the vegetation recovery after the operations in each plot.

Caesium-137 root uptake by agricultural and wild crops in post-Chernobyl landscape: the possibilities for phytoremediation?

NASA Astrophysics Data System (ADS)

Paramonova, Tatiana; Shamshurina, Eugenia; Komissarova, Olga; Belyaev, Vladimir

2015-04-01

In spite of long term period after Chernobyl fallout (≈25 years after the accident) the level of Cs-137 in soils of contaminated landscapes remains several times more than radiation safety standard (= 37 kBq/m2). In particular, within the area of Plavsk radioactive hot spot (Tula region, Russia) current Cs-137 activities in soil are 460-500 Bq/kg (170-200 kBq/m2) on watershed, 580-680 Bq/kg (200-220 kBq/m2) in arable lower parts of slopes and 620-710 Bq/kg (210-280 kBq/m2) in untilled foots of slopes and river floodplains. To estimate the process of Cs-137 root uptake and incorporation of the radionuclide in plant tissues 6 agricultural crops of typical field rotation (spring barley, maize, summer rape, galega, potatoes, amaranth) as well as natural ecosystems of dry and wet meadows were selected for the detailed study. Total bioproductivity of agricultural crops varies between 1.7-3.9 kg/m2, natural grass ecosystems - 1.9-2.2 g/m2, and is obviously unaffected by radioactive land contamination. At the same time Cs-137 activity in total biomass slightly increases with Cs-137 activity in soil (correlation coefficient r=0.45) and with total biomass (correlation coefficient r=0.51) in the row: rape (5 Bq/kg) < amaranth, galega (17-19 Bq/kg) < barley, potatoes (31-37 Bq/kg) < maize (58 Bq/kg) < dry meadow (73 Bq/kg) < wet meadow (120 Bq/kg). Commonly, Cs-137 activity in vegetation of natural ecosystems with predominance of perennial grasses is significantly higher than in agrosystems with annual crops. But a substantial portion of Cs-137 in meadow vegetation is associated with belowground biomass, where the radionuclide's activity is 3-5 times greater than in the aboveground part. The distribution of Cs-137 activities between above- and belowground parts of agricultural crops greatly varies depending on the biological characteristics of plants: barley and maize (Gramíneae family) are also characterized by elevated Cs-137 concentrations in belowground parts (12-14 times higher than in shoots); rape (Brassicaceae family) and potatoes (Solanaceae family) are characterized by similar Cs-137 concentrations in the structural parts (but note, that belowground part of the last is mostly represented by modified shoots); while galega and amaranth (Fabaceae and Amaranthaceae families respectively) are characterized by higher Cs-137 activity in aboveground part (4-6 times more than in roots). Therefore, meadow grasses and cereals that are true accumulators of Cs-137 seem to be useless for phytoremediation purposes, as 86-97% of the radionuclide inventory is associated with roots and remains in soil after cutting of aboveground parts. On the other hand, galega and amaranth could be considered as agricultural crops potentially being used for phytoremediation, since 87-93% of Cs-137 inventory is located in shoots. Potatoes having rather high aboveground biomass and easily removed from soil underground part could be also used for phytoremediation. However, it should be clearly understood that in total Cs-137 inventory in "soil-plant" system the annual amount of the radionuclide's consumption (that may be alienated when harvesting) is less than 0.01%, while the rate of Cs-137 radioactive decay is estimated as about 2% per year. Study was conducted with the support from the Russian Foundation for Basic Research (project no. 14-05-00903).

Partition Coefficients at High Pressure and Temperature

NASA Astrophysics Data System (ADS)

Righter, K.; Drake, M. J.

2003-12-01

Differentiation of terrestrial planets includes separation of a metallic core and possible later fractionation of mineral phases within either a solid or molten mantle (Figure 1). Lithophile and siderophile elements can be used to understand these two different physical processes, and ascertain whether they operated in the early Earth. The distribution of elements in planets can be understood by measuring the partition coefficient, D (ratio of concentrations of an element in different phases (minerals, metals, or melts)). (14K)Figure 1. Schematic cross-section through the Earth, showing: (a) an early magma ocean stage and (b) a later cool and differentiated stage. The siderophile elements (iron-loving) encompass over 30 elements and are defined as those elements for which D(metal/silicate)>1, and are useful for deciphering the details of core formation. This group of elements is commonly broken up into several subclasses, including the slightly siderophile elements (1104). Because these three groups encompass a wide range of partition coefficient values, they can be very useful in trying to determine the conditions under which metal may have equilibrated with the mantle (or a magma ocean). Because metal and silicate may equilibrate by several different mechanisms, such as at the base of a deep magma ocean, or as metal droplets descend through a molten mantle, partition coefficients can potentially shed light on which mechanism may be most important, thus linking the physics and chemistry of core formation. In this chapter, we summarize metal/silicate partitioning of siderophile elements and show how they may be used to understand planetary core formation.Once a planet is differentiated into core and mantle, a mantle will cool during convection, and can start in either a molten or solid state, depending upon the initial thermal conditions. If hot enough, minerals will crystallize from a molten mantle, and become entrained in the convecting melt, or eventually settle out at the bottom. The entrainment and settling process has been studied in detail (e.g., Tonks and Melosh, 1990), and is a potential mechanism for differentiation between the deep and shallow parts of Earth's mantle. The lithophile elements, those elements that have D(metal/silicate) <1, fall into many different subclasses and all hold information about the deep mineral structure of the mantle. Rare-earth elements (REEs) have proven to be useful: europium anomalies have helped elucidate the role of plagioclase in lunar crust formation (e.g., Schnetzler and Philpotts, 1971; Weill et al., 1974), and LREE/HREE depletion and enrichment are indicators of partial melting in the presence of garnet in the mantle. High-field-strength elements (HFSEs) - niobium, zirconium, tantalum, and hafnium - are all refractory and hence more resilient to fractionation processes such as volatility or condensation. They also have an affinity for ilmenite and rutile, and can explain differences between lunar and martian samples as well as features of Earth's continental crust ( Taylor and McLennan, 1985). Alkaline-earth and alkaline elements include rubidium, strontium, barium, potassium, caesium, and calcium, some of which are involved in radioactive decay couples, e.g., Rb-Sr and K-Ar. The latter is important in understanding the contribution of radioactive decay to planetary heat production, and potential deep sources of radiogenic argon (see Chapter 2.06). Rubidium and potassium are further useful as tracers of hydrous phases such as mica and amphibole. Possible fractionation of any of these elements from chondritic abundances (see Chapter 2.01) can be assessed with the knowledge of partition coefficients. In this chapter we summarize our understanding of mineral/melt fractionation of minor and trace elements at high pressures and temperatures and discuss the implications for mantle differentiation.

Geochemistry of Groundwater

NASA Astrophysics Data System (ADS)

Chapelle, F. H.

2003-12-01

Differentiation of terrestrial planets includes separation of a metallic core and possible later fractionation of mineral phases within either a solid or molten mantle (Figure 1). Lithophile and siderophile elements can be used to understand these two different physical processes, and ascertain whether they operated in the early Earth. The distribution of elements in planets can be understood by measuring the partition coefficient, D (ratio of concentrations of an element in different phases (minerals, metals, or melts)). (14K)Figure 1. Schematic cross-section through the Earth, showing: (a) an early magma ocean stage and (b) a later cool and differentiated stage. The siderophile elements (iron-loving) encompass over 30 elements and are defined as those elements for which D(metal/silicate)>1, and are useful for deciphering the details of core formation. This group of elements is commonly broken up into several subclasses, including the slightly siderophile elements (1104). Because these three groups encompass a wide range of partition coefficient values, they can be very useful in trying to determine the conditions under which metal may have equilibrated with the mantle (or a magma ocean). Because metal and silicate may equilibrate by several different mechanisms, such as at the base of a deep magma ocean, or as metal droplets descend through a molten mantle, partition coefficients can potentially shed light on which mechanism may be most important, thus linking the physics and chemistry of core formation. In this chapter, we summarize metal/silicate partitioning of siderophile elements and show how they may be used to understand planetary core formation.Once a planet is differentiated into core and mantle, a mantle will cool during convection, and can start in either a molten or solid state, depending upon the initial thermal conditions. If hot enough, minerals will crystallize from a molten mantle, and become entrained in the convecting melt, or eventually settle out at the bottom. The entrainment and settling process has been studied in detail (e.g., Tonks and Melosh, 1990), and is a potential mechanism for differentiation between the deep and shallow parts of Earth's mantle. The lithophile elements, those elements that have D(metal/silicate) <1, fall into many different subclasses and all hold information about the deep mineral structure of the mantle. Rare-earth elements (REEs) have proven to be useful: europium anomalies have helped elucidate the role of plagioclase in lunar crust formation (e.g., Schnetzler and Philpotts, 1971; Weill et al., 1974), and LREE/HREE depletion and enrichment are indicators of partial melting in the presence of garnet in the mantle. High-field-strength elements (HFSEs) - niobium, zirconium, tantalum, and hafnium - are all refractory and hence more resilient to fractionation processes such as volatility or condensation. They also have an affinity for ilmenite and rutile, and can explain differences between lunar and martian samples as well as features of Earth's continental crust ( Taylor and McLennan, 1985). Alkaline-earth and alkaline elements include rubidium, strontium, barium, potassium, caesium, and calcium, some of which are involved in radioactive decay couples, e.g., Rb-Sr and K-Ar. The latter is important in understanding the contribution of radioactive decay to planetary heat production, and potential deep sources of radiogenic argon (see Chapter 2.06). Rubidium and potassium are further useful as tracers of hydrous phases such as mica and amphibole. Possible fractionation of any of these elements from chondritic abundances (see Chapter 2.01) can be assessed with the knowledge of partition coefficients. In this chapter we summarize our understanding of mineral/melt fractionation of minor and trace elements at high pressures and temperatures and discuss the implications for mantle differentiation.

Rare isotope beam energy measurements and scintillator developments for ReA3

NASA Astrophysics Data System (ADS)

Lin, Ling-Ying

The ReAccelerator for 3 MeV/u beams (ReA3) at the National Superconducting Cyclotron Laboratory (NSCL) in Michigan State University can stop rare isotope beams produced by in-flight fragmentation and reaccelerate them in a superconducting linac. The precise knowledge of the energy and the energy spread of the ion beams extracted from the ReA3 linac is essential for experimental requirement in many applications. Beam energy determination methods such as implantation on a Si detector and/or using calibrated linac settings are precise within a few tens of keV/u. In order to determine beam energies with good resolution of less than 0.5 % FWHM, a 45 degree bending magnet with a movable slit is used to determine the absolute beam energy based on the magnetic rigidity. Two methods have been developed for the energy calibration of the beam analyzing magnet: gamma-ray nuclear resonance reactions and a time-of-flight (TOF) technique. The resonance energies of gamma-ray resonant reactions provide well-known and precise calibration points. The gamma ray yields of the 27Al(p,gamma)28Si at Ep= 992 keV and 632 keV resonances and 58Ni(p,gamma)59Cu at Ep= 1843 keV resonance have been measured with the high efficiency CAESAR (CAESium iodide ARray) and SuN (Summing NaI(Tl)) detectors. By fitting the observed resonant gamma-ray yields, not only the beam energy can be precisely correlated with the magnetic field but also beam energy spread can be obtained. The measured beam energy spread is consistent with beam optics calculations. A time-of-flight system for determining the absolute energy of ion beams and calibrating the 45 degree magnetic analyzer has been developed in ReA3 by using two identical secondary electron monitors (grid-MCP detectors) with appropriate separation. The TOF technique is applicable to the variety of beam energies and ion particles. Velocities of ion beam are determined by simultaneously measuring the arrival time of beam bunches at the two detectors with respect to the acceleration RF clock. The time-of-flight system can provide beam energy information with precision of <0.1%. Scintillators are widely used to reliably measure beam profiles and beam distributions. At low energies, scintillator-based diagnostic devices are more problematic because of their fast light yield degradation under ion bombardment. The degradation of the scintillation yield of single crystal YAG: Ce under He+ irradiation at low energies between 28 and 58 keV has been systematically studied. The scintillator was irradiated at the rare isotope ReAccelerator (ReA) facility. The scintillation emission is attributed to its rapid 5d-4f transition of Ce3+ ions. As the bombardment time increases, an exponential decay of the light output is observed due to the induced radiation damage of the crystal lattice. The decrease of the experimentally observed light yield as a function of particle fluence is found to be in fair agreement with the Birks model. Analysis indicates that the damage cross section of scintillation centers slightly decreases with the ion energy. The scintillator degrades slower under higher-energy irradiation. In order to investigate scintillation degradation over a wide range of irradiation energies and scintillator materials, the scintillation processes for KBr, YAG:Ce, CaF2:Eu and CsI:Tl crystals under H2 + irradiation in the energy range of 600-2150 keV/u have been investigated. The data indicates that YAG:Ce and CsI:Tl can maintain stable luminescence under continuous ion bombardment for at least a total fluence of 1.8x10 12 ions/mm2. On the other hand, the luminescence of CaF2:Eu shows a rapid initial decay but then maintains a nearly constant luminescence yield. The extraordinary scintillation response of KBr is initially enhanced under ion bombardment, approaches a maximum, and then eventually decays. The scintillation efficiency of the CsI:Tl scintillator is superior to the other materials. The low-energy H2+ bombardment (25 keV/u) on the YAG:Ce scintillator can lead to the significant degradation of the scintillation yields. Different scintillation degradation responses for the low- and high-energy bombardments can be attributed to the transmission loss of the emitted light inside the crystal caused by displacement damages.

Continuum Theory (CT):. Its Particle-Tied Aether Yields a Continuous Auto-creation, Non-expanding Cosmology and New Light on Galaxy Evolution and Clusters

NASA Astrophysics Data System (ADS)

Osmaston, Miles F.

2013-09-01

Our preceding paper "Implementing Maxwell's aether......." (Paper I) concluded:- (A) Maxwell's aether, ignored in Relativity, is a massless, quasi-superfluid continuum of extremely high negative charge density; (B) Fundamental particles are not infinitesimal singularities within the aether but develop their mass by being `made out of it' (hence the name Continuum Theory) as finite-sized vortical constructs of its motion. So reproduction (`auto-creation') of more of them requires only the addition of suitable dynamical energy, with Ampere's law providing charge-coupling in shear to get rotations. (C) In the resulting gravitational process, generating the Newtonian force simultaneously also generates a radial electric field, the Gravity-Electric (G-E) field, whose action on astronomical plasmas could explain the flat tangential velocity profiles of spiral galaxies without resort to Cold Dark Matter (CDM) if outward disc flow is present. One of the objectives here is to provide that flow by axial infall and to examine its consequences. But first, if particles are `made out of aether' the associated random aether-charge motion will generate radiation (the CMB) and impose four distance-cumulative, wavelength-independent transmission effects upon electromagnetic waves. One of these - a redshift - we see here as the cosmic redshift, plus intrinsic redshifts in stellar and galaxy `atmospheres'. Such a redshift appears to have been reliably observed with caesium clocks over long ground-level paths in 1968 but, lacking an appreciation of its mechanism, its wide significance was doubted. In fact, our extrapolation to intergalactic conditions dispenses with the BigBang. The other 3 transmission effects are:- spectral line broadening, scattering and attenuation, each of which has significant astronomical/cosmological expression. If the cosmic redshift is not a velocity, the reason for Dark Energy vanishes. In the resulting no-expansion cosmology the Universe was originally equipped with randomly moving aether, from whose motion and energy content the entire mass content of the Universe has grown over time by auto-creation, the local rate of which experiences positive feedback and acceleration as gravitational accumulations drive energy levels higher. Hence the clumpiness of galaxy distributions. The infall of cosmogonally young material from the auto-creation auras of clusters has 3 major implications. (1) It completely inverts the Big Bang perspective that lowmetallicity material, widespread in galaxy haloes, is very ancient. (2) Quasi-axial infall of such broadly neutral material (mostly H) onto a Spiral will spread out in the galactic plane, driven radially from the ionizing bulge by the G-E field, maintaining constant tangential velocity; all without CDM. This pattern means that the arms, although trailing, are actually being blown outward (unwrapping). See Paper I for detail. For such ongoing disruption of Spirals to prevail so widely means that originally each must have started life as an a.m.-conserving, tightly-wound spiral of mostly neutral, cosmogonically young material (mainly H), in which G-E field action was minimal until star formation and ionization had set in. (3) In cluster interiors, other cluster members may deflect the two infall streams as they converge onto a Spiral, introducing a dynamical rotational couple near the centre, with an axis roughly in the galactic plane, to produce a Barred Spiral. Cessation of infall then results in endwise collapse of that bar, yielding a fattened Elliptical. Those are indeed typically concentrated in the centres of clusters and show a dearth of active star formation, consistent with being deprived of young infall. We present images and diagrams in support and elaboration of (2) and (3). The CT model for quasars provides large intrinsic redshift by the CT analogue of Transverse Doppler Effect and offers light-element synthesis by the evolutionary precipitation of a runaway rotational shrinkage, with mass annihilation and emission of a GRB. Of special interest, relative to the arm's-length nature of BigBang cosmology, is that continuous auto-creation (CAC) cosmology is in principle available near-by for direct study and the development of strong observational constraints. In the context of (1), the very low metallicity (Pop II) of globular (star) clusters abundantly present in the haloes of galaxies points to them being (infallen?) local concentrations of quite young auto-creation. In that case the `blue straggler' stars more recently formed in their core regions may be our youngest examples of ongoing auto-creation. In summary, CT offers a much more directly observable Universe, with no Big Bang, CDM, or Dark Energy, and a CMB that records the true temperature of intergalactic space along the path taken by the radiation. Its closely cavity-radiation character arises from the random aether's transmission-related opacity (Olbers' Paradox) of the infinite CT Universe. Fundamentally, the aether's random motion constitutes all-penetrating random electromagnetic excitation at the atomic scale that may offer the accommodation between classical physics and stochastic quantum electrodynamics so long obstructed by Relativity Theory.

Quantification Of Erosion Rates Of Agriculturally Used Soils By Artificial

NASA Astrophysics Data System (ADS)

Jha, Abhinand

2010-05-01

0.0.1 1. Introduction to soil erosion measurement by radionuclides Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Studying this phenomenon would be one of the advancements in science. Soil erosion occurs worldwide and since the last two decades it has been a main topic of discussion all over the world. The use of environmental radionuclides such as 90Sr, 137Cs to study medium term soil erosion (40 yrs) started in the early 1990's. Using these new techniques better knowledge about erosion can be gained and this knowledge can be implemented for erosion risk management. The erosion and sedimentation study by using man-made and natural radioisotopes is a key technique, which has developed over the past 30 years. Fallout 137Cs and Cosmogenic 7Be are radionuclides that have been used to provide independent measurements of soil-erosion and sediment-deposition rates and patterns [1] [2] [3] [4]. Erosion measurements using radionuclides 137Cs, 7Be Caesium-137 from atmospheric nuclear-weapons tests in the 1950s and 1960s (Fig.1) is a unique tracer of erosion and sedimentation, since there are no natural sources of 137Cs. Unique events such as the Chernobyl accident in April 1986 caused regional dispersal of 137Cs that affects the total global deposition budget. This yearly pattern of fallout can be used to develop a chronology of deposition horizons in lakes, reservoirs, and floodplains. 137Cs can be easily measured by gamma spectroscopy. Using 137Cs is a fast and cheap method to study erosion-deposition processes compared to the traditional methods like silt bags. PIC Figure 1: Global 137Cs fallout (Modified from SAAS Bulletin 353, Part E, DDR, 1986) When 137Cs, 7Be reach the soil surface by wet and dry deposition, they are quickly and strongly adsorbed by ion exchange and are essentially non exchangeable in most environments. Each radionuclide is distributed differently in the soil because of differences in half-lives (30 yrs for 137Cs and 53 days for 7Be), delivery rates, delivery histories, and land use (Fig. 2). An Physical processes, such as water and wind, are the dominant factors moving 137Cs, 7Be tagged soil particles within and between landscape compartments. PIC Figure 2: Generalized sketch illustrating the distributions of 137Cs and 7Be in tilled and undisturbed soils 2 Erosion study at Young Moraine regions of Germany Recently, a study had been performed to evaluate erosion rates in a typical pattern of landscapes in the Young Moraine regions of North-East Germany [5]. The 137Cs concentrations were measured at selected sampling points of various study sites. Among the areas selected for sampling was Basedow, which is a cultivated area, situated north of Berlin. During a master thesis study at university of Bremen in the academic year 2008-2009 [6] a second sampling campaign was performed at the same study site and 137Cs and 7Be concentrations were measured. Two mathematical models (a proportional model and a mass balance model) were applied to estimate erosion or deposition rates giving a distinction between uncultivated or essentially undisturbed soils and cultivated or soils under permanent pasture (Fig.3A). An improved depositional model was developed during this study. The simulation results from this model are presented in Fig.4. Due to the half-life (53.2 days) of 7Be, a mass balance model was developed and used to calculate erosion rates from 7Be (Fig.3B). PIC Figure 3: A: Erosion rates for 137Cs calculated by mass balance model. B: Erosion rates calculated with mass balance model using the 7Be data at Basedow (2008). The results verify that there is long term erosion as a result of wind, water and agricultural practices. The annual erosion rates at Basedow calculated using a mass balance and a proportional model were in the range between 30-50 t ha-1yr-1. These values were comparable to the erosion rates calculated in the previous study [5] by the models mentioned above. PIC Figure 4: Profiles of sediment calculated for different erosion rates by Cs-137 within the ploughed soil 3 Conclusions and outlook Erosion rates for agricultural soils at Young Moraine regions of North-East Germany were determined by using two radionuclides, 137Cs and 7Be. In combination, the two radionuclides provide a valuable means of investigating soil erosion and assessing erosion risk in the study area. Potentials and limitations of the erosion measurement techniques using radiotracers are discussed in this study. The models used to quantify erosion rates using 137Cs and 7Be were studied. Erosion rates calculated by theses models are difficult to measure over a period of 50 years. A validation of these erosion rates for the time period (50 years) used in the 137Cs-based models will give a new perspective to the use of soil erosion modeling. Most of the regions in India are suffering from high erosion rates [7]. By using the new techniques in erosion quantification the land management practices can be improved and the erosion risk can be reduced in India.

Book Review:

NASA Astrophysics Data System (ADS)

Sanders, J. H.

1984-01-01

The NATO Advanced Study Institute held at Erice, Sicily, in November 1981 brought together specialists in precise measurement to present a tutorial introduction to quantum metrology and the measurement of the fundamental physical constants. Ever since the evolution of experimental physics as a scientific pursuit the measurement of the values of quantities accepted to be constants of nature has commanded the attention of some of the world's most accomplished workers in this field. Their efforts to seek out the sources of systematic error and to reduce the random errors have produced significant advances in techniques and a continual interest in their results from users and critics: as Raymond T Birge, who pioneered the evaluation of the 'best' values of the constants from the available measurements, observed (perhaps with tongue-in-cheek) "it is the continual variation in the values of these quantities that furnishes most of the interest in the subject". Long before the recognition of the fundamental constants the measurement of mass, length and time grew as a matter of necessity in organized communities, especially in agriculture, commerce and navigation. The adoption of standards, first local, then national, and now international, was a natural consequence. It is particularly relevant that the published proceedings of the NATO school opens with a historical survey by Pierre Giacomo of the Bureau International des Poids et Mesures, which places the subsequent papers in perspective. Measurements which realize the standards of length and time, and those from which values of the fundamental constants are derived, are of such a nature that a considerable background knowledge of physics is needed for their understanding. (The principle of the caesium frequency standard and the physics of the Josephson junction are a long haul from Michelson's measurement of the speed of light and the Millikan oil drop experiment familiar in the school books.) With this in mind, George Series presents as an introductory article a characteristically clear résumé of the quantum mechanical background of spectroscopy which, although too condensed to compete with the textbooks, provides an admirable checklist of what one needs to know. Pierre Cerez does the same for the physics of masers and lasers, and follows this with an account of present-day time and frequency standards. The establishment and world-wide distribution of these standards, and the related subjects of length, wavelength and optical frequency standards are covered in detail, and more history is related in a review of past measurements of the speed of light. Now that the measurement of the speed of light has become an irrelevance as a result of its definition as an exact quantity, thus abolishing the need for a direct standard of length, the article by K M Baird is bound to rouse nostalgia. In this connection it is a delight to find reprinted at the end of the volume the text of the article, published in 1773, giving an account of Roemer's method (1676) for measuring the speed of light and the first indication that it is finite. The most significant impact on the measurement of the fundamental constants was made by the discovery of quantum effects and the development of the quantum theory. Planck's constant plays the key role here, and quantum metrology has merged the quantum and classical fields. Thus the volt can be referred to a frequency, through the Josephson effect, in a particularly (and unexpectedly) direct manner, and magnetic field strengths can be compared as a ratio of frequencies, and measured in terms of the gyromagnetic ratio of the proton. Techniques of this sort are reviewed by Brian Petley of the National Physical Laboratory, who also contributes valuable articles on the particular measurements which involve magnetic moments, and a general survey of the significance of the fundamental constants as a whole. Laser spectroscopy has in recent years played an important part in the measurement of quantities, such as the fine-structure constant, which are related to fundamental constants, and in tests of quantum electrodynamics. A clear example of this is given in an article by Carl Wieman of the University of Michigan illustrating the spectacular advances that have been made in resolving the spectrum of atomic hydrogen by saturated absorption techniques. On a more practical note, there are articles on the application of metrological techniques to geoscience and astrophysics, and, in particular, of precise time and frequency measurements to navigation, gravity and positioning. Richard Cohen, who has been concerned with the subject for a considerable time, summarizes the present status of the fundamental constants, and as a tail-piece of the volume there are a number of seminar contributions on specialized topics. The scope of the volume is wide-ranging, both in subject matter and level. Its primary aim, as was the aim of the NATO school, is tutorial, and in this it succeeds admirably. The choice, both of authors and titles, ensures this; but there is more besides. Those already familiar with the field can still find much of interest in the review articles and in the more specialized contributions. It is a source of instruction for the beginner and a place for the expert to browse.

Electrical quantum standards and their role in the SI

NASA Astrophysics Data System (ADS)

Robinson, Ian; Georgakopoulos, Dimitrios

2012-12-01

The International System of Units, SI, is poised to make a quantum change and become a measurement system based entirely on the fundamental properties of the natural world. In the next version of the SI, the Planck constant h, the elementary charge e, the Avogadro constant NA and the Boltzmann constant k will be fixed, in addition to the already fixed values of the speed of light c and the ground state hyperfine splitting in caesium-133. As a result, six out of the seven base units of the SI will be based directly on true invariants of nature. A major part of this change has been enabled by the ready availability of electrical quantum standards of exquisite precision and mechanisms for using them to make measurements outside the electrical arena. The overall effect will be to eliminate the remaining imprecise definitions of physical units associated with the use of artefact standards and aid direct SI measurements without problems of scaling. Fixing the Planck constant and the elementary charge will have the effect of incorporating the best physical realizations of electrical quantities into the SI, providing a system of units fit for the 21st century. The purpose of this special feature is to review the status of electrical quantum standards and report the latest developments in those areas and their applications to other areas of metrology. The special feature coincides with the 50th anniversary of the seminal paper of Josephson, 'Possible new effects in superconductive tunnelling' [1], which established the basic physical principle upon which the quantum voltage standards are based. Josephson voltage standards are based on the inverse Josephson effect. When a junction of two superconducting electrodes, weakly linked through a thin insulator or a normal metal, is irradiated with a radiofrequency electromagnetic field of frequency f and is biased by a dc current, then the voltage across the junction is quantized (i.e. small changes in either the dc current or the power of the rf irradiation, or both, do not change the voltage). The value of this quantized Josephson voltage is equal to nfh/2e, where n is the quantum step of the current-voltage characteristic curve. In this special feature there are three papers on dc Josephson voltage standards. Solve and Stock review the programme conducted by the Bureau International des Poids et Mesures (BIPM) to perform on-site comparisons of Josephson voltage standards, and give a comprehensive analysis of the possible sources of errors of such comparisons. Behr et al summarize the developments of Josephson voltage standards at Physikalisch-Technische Bundesanstalt (PTB) and their applications in dc voltage and other areas of metrology. Finally, Georgakopoulos et al report a reduction, by a factor of a thousand, in the smallest voltage that can be generated by dc Josephson voltage standards. Although dc voltage standards are well established, significant challenges exist when extending this extremely precise technology to ac. There are two approaches to producing accurate ac voltages using the inverse Josephson effect: the programmable Josephson voltage standard (PJVS) and the pulse-driven ac voltage standard. The PJVS contains an array of Josephson junctions, organized into independently biased segments. By biasing chosen, binary-related, segments on the first quantum step (positive or negative) or zero, the array can be made to behave as a quantum digital to analogue converter. The PJVS approach can produce stepwise approximated sine waves with rms values of some volts, but it suffers from parasitic capacitances and inductances distributed in the different parts of the system and, more importantly, the voltage is not quantized during the finite transition time between successive voltage levels. Hence the output frequency of PJVS-based systems is limited to a few kilohertz. In this special feature, Jeanneret et al review the Josephson locked synthesizer, a PJVS-based system where the effect of transients between successive steps on the output voltage is reduced. This special feature also presents two applications of PJVS-based quantum voltage standards: the evaluation of conventional ac voltage standards based on thermal converters (Budovsky et al) and the measurement of the settling time of a high resolution digital voltmeter (Henderson et al). In the pulse-driven ac voltage standard, arbitrary voltages can be produced by modulating the rf irradiation of an array of Josephson junctions by a series of high frequency pulses, usually by means of Δ-Σ modulation. The output voltage of the array of junctions is a series of quantized voltage pulses that correspond to the desired waveform after the high frequency components are removed. The pulse-driven standard can operate at much higher frequencies than the PJVS. Eliminating the effects of parasitic impedances of the, necessarily long, connecting leads therefore becomes a significant challenge. In this special feature, van den Brom and Houtzager report a voltage lead correction technique. Quantum resistance standards are based on the quantum Hall effect in which the resistance of a two-dimensional electron gas in a strong magnetic field is quantized. The value of the quantized Hall resistance is h/ie2, where i is the number of the quantum step in the resistance-magnetic field curve. Quantum Hall resistance devices can be combined in series to form a resistive voltage divider with low uncertainty in the ratio. In this special feature, Domae et al report the realization of such a resistive voltage divider on a chip. Quantum Hall resistance standards have been routinely used at dc for over two decades. However, the operation of quantum Hall devices at ac is complicated by the flow of current in capacitances around the device, which can compromise measurement of its resistance. Schurr et al review the status of ac quantum Hall resistance standards and their role in the SI. Ohm's law can be applied to quantum realizations of voltage, resistance and current to test their consistency. Active research into this 'metrological triangle' is underway and, at present, there is no evidence to indicate a discrepancy at any level. However, work is continuing on current sources which utilize a countable flow of electrons (the electric current produced is proportional to ef, f being the operating frequency of the device), but the work has some way to go before the question of consistency can be resolved at levels approaching 1 part in 109. In this special feature, Scherer and Camarota review the state-of-the-art of metrological triangle experiments and Devoille et al report on the status of the metrological triangle experiment at the Laboratoire National de Métrologie et d'Essais (LNE), France. The availability of precise representations of the volt and the ohm based on quantum mechanics has enabled the watt balance, an apparatus which relates electrical and mechanical power, to link the kilogram to the Planck constant. This has paved the way for the proposed redefinition of the kilogram, the last artefact standard in the SI, in terms of a fixed value of the Planck constant. In the past few years a number of papers, e.g. [2, 3], have been published describing the working principles of the watt balance and the characteristics of the existing implementations of the experiment. The measurements of the principal quantities—mass, velocity, gravitational acceleration, resistance and voltage—are reasonably well documented but the ultimate precision of the apparatus depends on a number of techniques that are required to eliminate second-order effects. In this special feature, Robinson provides details of these general alignment techniques with special reference to the NPL Mark II watt balance. Acknowledgments We would like to thank the authors for supporting the special feature with their excellent contributions; the guardians of the quality of a scientific paper, the referees, for their valuable comments and suggestions; Professor Wuqiang Yang and the members of the editorial board of Measurement Science and Technology for their support. Finally, we would like to thank Dr Sharon D'Souza, James Dimond and all the editorial and publication staff at Measurement Science and Technology, for their help in making the special feature a reality. References [1] Josephson B D 1962 Possible new effects in superconductive tunnelling Phys. Lett. 1 251-3 [2] Li S, Han B, Li Z and Lan J 2012 Precisely measuring the Planck constant by electromechanical balances Measurement 45 1-13 [3] Stock M 2011 The watt balance: determination of the Planck constant and redefinition of the kilogram Phil. Trans. R. Soc. A 369 3936-53