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Sample records for caesium isothermal migration

  1. Caesium and plutonium migration in forest soils of the Chernobyl 30 km zone

    International Nuclear Information System (INIS)

    Vertical distributions of radiocaesium and plutonium inventories and uranium ratios (238U:235U) are presented for forest soils at three sites within the Chernobyl 30 km exclusion zone. The uranium ratios indicate the presence of reactor fuel fragments ('hot particles') at all sites, but with declining significance with distance from the ChNPP. Caesium and plutonium distributions in soil profiles were evaluated using a compartmental model to derive migration half times for each horizon. Migration rates at each site were lowest for the AoH horizon. The AoH horizon at the site with the largest apparent population of 'hot particles' exibited the longest caesium and plutonium migration half times, which generally decreased with distance from the ChNPP (i.e. with decreasing 'hot particle' densities). Plutonium appears to be more mobile than radiocaesium, possibly due to the movement of soluble Pu humic complexes formed within the surface organic soil horizons. (author)

  2. Type I Migration in a Non-Isothermal Protoplanetary Disk

    CERN Document Server

    Jang-Condell, H; Jang-Condell, Hannah; Sasselov, Dimitar D.

    2004-01-01

    We calculate rates of Type I migration of protoplanets in a non-isothermal three-dimensional protoplanetary disk, building upon planet-disk models developed in previous work. We find that including the vertical thickness of the disk results in a decrease in the Type I migration rate by a factor of ~2 from a two-dimensional disk. The vertical temperature variation has only a modest effect on migration rates since the torques at the midplane are weighted heavily both because the density and the perturbing potential are maximized at the midplane. However, temperature perturbations resulting from shadowing and illumination at the disk's surface can decrease the migration rate by up to another factor of 2 for planets at the gap-opening threshold at distances where viscous heating is minimal. This would help to resolve the timescale mismatch between the standard core-accretion scenario for planet formation and the survival of planets, and could help explain some of the rich diversity of planetary systems already ob...

  3. Study of caesium sorption on Na and Ca-Mg bentonites using batch and diffusion experiments

    International Nuclear Information System (INIS)

    In most deep geological repository concepts sorption of radionuclides on bentonite represents a very important process in retarding radionuclide migration into geosphere. Despite a huge amount of studies concerning caesium sorption on bentonites, there are still some problems requiring deeper clarification. One of the most important issues is the difference between distribution coefficients (Kd) obtained using batch and diffusion experiments. The results of a comprehensive study of caesium sorption on Na bentonite (industrial sorbent Volclay KWK 20-80, Suedchemie, Germany) and Ca-Mg bentonite (raw bentonite, Rokle deposit, Czech Republic) using both of these methods suggest that the reasons of this difference can originate from different sources connected with conditions of experiments and the ways of their evaluation. The main uncertainties of caesium sorption on two different bentonites using the batch method were described and the influence on sorption has been demonstrated. Detailed mineralogical and chemical analysis of bentonite samples confirmed the differences in mineral composition and physical-chemical properties of selected bentonite types. These data are necessary for better understanding of their sorption behaviour and for sorption results evaluation. The results suggest that caesium-selective minerals present in bentonites as admixtures can govern the sorption behaviour of caesium on different bentonites at its trace concentrations. At higher concentrations, the ion exchange on non-selective sites dominates the sorption and can be well-described using sorption isotherms and ion-exchange models. It also follows from the performed experiments that the caesium sorption on studied bentonites cannot be described using the simple Kd method that is often used to evaluate distribution coefficients from diffusion experiments. The uncertainties of evaluation of sorption coefficients from diffusion experiments can also be connected with the way of diffusion

  4. Near-isothermal conditions in the middle and lower crust induced by melt migration.

    Science.gov (United States)

    Depine, Gabriela V; Andronicos, Christopher L; Phipps-Morgan, Jason

    2008-03-01

    The thermal structure of the crust strongly influences deformation, metamorphism and plutonism. Models for the geothermal gradient in stable crust predict a steady increase of temperature with depth. This thermal structure, however, is incompatible with observations from high-temperature metamorphic terranes exhumed in orogens. Global compilations of peak conditions in high-temperature metamorphic terranes define relatively narrow ranges of peak temperatures over a wide range in pressure, for both isothermal decompression and isobaric cooling paths. Here we develop simple one-dimensional thermal models that include the effects of melt migration. These models show that long-lived plutonism results in a quasi-steady-state geotherm with a rapid temperature increase in the upper crust and nearly isothermal conditions in the middle and lower crust. The models also predict that the upward advection of heat by melt generates granulite facies metamorphism, and widespread andalusite-sillimanite metamorphism in the upper crust. Once the quasi-steady-state thermal profile is reached, the middle and lower crust are greatly weakened due to high temperatures and anatectic conditions, thus setting the stage for gravitational collapse, exhumation and isothermal decompression after the onset of plutonism. Near-isothermal conditions in the middle and lower crust result from the thermal buffering effect of dehydration melting reactions that, in part, control the shape of the geotherm. PMID:18322532

  5. Caesium radionuclides migration in an alluvial soil of the Po River Valley (Northern Italy) after the Chernobyl nuclear accident

    International Nuclear Information System (INIS)

    Investigation was carried out to study the migration of Cs-137 and Cs-134 deposited by the radioactive cloud from Chernobyl. Distribution depth profiles and diffusion coefficients are reported and correlated to soil quality parameters. (orig./HP)

  6. Sorption/desorption processes of caesium and strontium in soil: is the Kd-concept adequate?

    International Nuclear Information System (INIS)

    Interaction with the soil matrix is one of the key processes for the migration of radionuclides in the terrestrial environment. Usually it is modeled by a simple distribution coefficient Kd of trace concentrations between solid and liquid phases. Laboratory experiments using a modified diffusion technique have been performed to study the interaction of caesium with a Eutric Cambisol soil pellet. Of the sorption models tested, assuming first order kinetics incorporating a Freundlich isotherm resulted in the best fit to the experimental data. The Kd model completely failed to describe the experimental data. Desorption showed a marked hysteresis. (author)

  7. Caesium incorporation and retention in illite interlayers

    OpenAIRE

    Fuller, AJ; Shaw, S.; Ward, MB; Haigh, SJ; Mosselmans, JFW; Peacock, CL; Stackhouse, S.; Dent, AJ; Trivedi, D; Burke, IT

    2015-01-01

    Radioactive caesium (chiefly 137Cs) is a major environmental pollutant. The mobility of Cs in temperate soils is primarily controlled by sorption onto clay minerals, particularly the frayed edges of illite interlayers. This paper investigates the adsorption of Cs to illite at the molecular scale, over both the short and long term. Transmission electron microscopy (TEM) images showed that after initial absorption into the frayed edges, Cs migrated into the illite interlayer becoming incorporat...

  8. Sorption and migration of radiocaesium in natural zeolite-water systems

    International Nuclear Information System (INIS)

    The sorption properties for caesium and its migration in a system zeolite-aqueous solution were studied for natural zoelites from Zaloshka gorica. It was found that zeolites are rather efficient sorbents for caesium even in the presence of some other electrolytes. A correlation between the rate of migration of caesium in the system zeolite-water and the sorption intensity was established. Migration of caesium from a zeolite layer by diffusion is described. (author) 7 refs.; 2 figs,; 1 tab

  9. Human metabolism of caesium

    Energy Technology Data Exchange (ETDEWEB)

    Raeaef, C.L. [Lund Univ., Dept. of Radiation Physics in Malmoe (Sweden); Falk, R. [Swedish Radiation Protection Authority (Sweden); Lauridsen, Bente [Risoe National Lab. (Denmark); Rahola, T. [STUK - Radiation and Nuclear Safety Authority (Finland); Soogard-Hansen, J. [NRPA - Norwegian Radiation Protection Authority (Norway)

    2006-04-15

    A study of the human biokinetics of caesium in two forms, i.) incorporated in foodstuff (137Cs in perch and mushrooms) and ii.) in ionic state ({sup 134}Cs in aqueous solution) has been carried out at the department of Radiation Physics in Malmoe, starting in 2001. The results of the pilot study were published in 2004, and a continuation of that study has now been carried out by means of NKS funding (NKS-B Cskinetik). The aim is to, i.) investigate whether Scandinavian populations exhibit shorter biological half-time of radiocaesium than other populations; ii.) extend the biokinetic study to additional human subjects from the other Nordic countries. Results from the continued study further indicate a near complete absorption of radiocaesium in the gastro-intestinal tract, be it in ion state or contained in food matrix. So far, the literature survey of Nordic studies on biokinetics of Cs suggests that the biological half time is somewhat shorter among Scandinavian males (84 days vs. ICRP-value of 110 days), although females do not exhibit any significant difference (64 days vs ICRP value of 65 days). (au)

  10. Human metabolism of caesium

    International Nuclear Information System (INIS)

    A study of the human biokinetics of caesium in two forms, i.) incorporated in foodstuff (137Cs in perch and mushrooms) and ii.) in ionic state (134Cs in aqueous solution) has been carried out at the department of Radiation Physics in Malmoe, starting in 2001. The results of the pilot study were published in 2004, and a continuation of that study has now been carried out by means of NKS funding (NKS-B Cskinetik). The aim is to, i.) investigate whether Scandinavian populations exhibit shorter biological half-time of radiocaesium than other populations; ii.) extend the biokinetic study to additional human subjects from the other Nordic countries. Results from the continued study further indicate a near complete absorption of radiocaesium in the gastro-intestinal tract, be it in ion state or contained in food matrix. So far, the literature survey of Nordic studies on biokinetics of Cs suggests that the biological half time is somewhat shorter among Scandinavian males (84 days vs. ICRP-value of 110 days), although females do not exhibit any significant difference (64 days vs ICRP value of 65 days). (au)

  11. Radioactive caesium in British mushrooms

    International Nuclear Information System (INIS)

    Thirty-four different taxa of larger fungi have been analysed for their content of caesium 137 over a 3 year period. The majority of the material has been collected from various sites in Central Scotland; 38% of the collections were from North Wales and Merseyside. Comparison has been made between the same species from different sites and different species from the same site. It has also been possible to analyse the same species from the same plot on two consecutive years. The levels of caesium 137 in the fungal species analysed were extremely low when compared with their counterparts in Central Europe and it is concluded that the Chernobyl incident had little effect on the accumulation by these fungi of this radionuclide. There is no evidence that edible species accumulate caesium 137 at levels considered to be dangerous for consumption

  12. The behaviour of caesium in mountainous soils

    International Nuclear Information System (INIS)

    In the mountainous area of the Friuli-Venezia Giulia region (North-Eastern part of Italy) the Cs-137 deposition, due to Chernobyl accident, ranged from 20 to 40 kBq/m2. To study the vertical migration of radionuclides in mountainous soils, ENEA-DISP and the Regional Centre for Agricultural Experimentation (C.R.S.A.) have located four sampling stations in areas selected on vegetational basis: two in deciduous forests, one in a Abies-Fagus forest and one in a natural grassland. In these sampling stations soil chemico-physical characteristics were determined (soil texture, pH and organic matter) and the meteorological parameters daily recorded. This paper presents caesium residence half times in the superficial soil horizons evaluated on the bases of results obtained from June 1987 to December 1988. (author)

  13. Caesium concentration in the Pakistani diet

    International Nuclear Information System (INIS)

    Daily dietary intakes of radioactive and non-radioactive caesium for the Pakistani population were measured. Food samples were collected on market basket method and were analysed using Instrumental Neutron Activation Analysis technique. The radioactive caesium (137Cs) in these samples was below the detectable limit, i.e. 1 mBq g-1. The geometric mean of the mass fraction of stable caesium was 9.56x1.53 ng g-1. The estimated daily dietary intake of caesium was 5.65x1.53 μg d-1 or 0.088 μg kg-1 of body weight of the reference Pakistani man weighing 64 kg. These values are 38.2% smaller than the recommended ICRP values for a 70 kg standard man. However, caesium concentration in the Pakistani diet is comparable with other reported values in the literature

  14. Leakage of caesium braquitherapy sources

    International Nuclear Information System (INIS)

    In several Venezuelan public hospitals where cervix uteri tumours are treated by intracavitary radiotherapy, that use manual after loading Fletcher method, with Caesium 137 sources, the use of improper source holders, locally manufactured from pieces of drainage plastic tubing, which deteriorated and created a corrosive environment all around the sources, omission of manufacturer's recommendations regarding corrosion information, source storage, inspection and testing, violation of International Atomic Energy Agency Radiation Protection Procedures, and lack of proper regulatory control, resulted integrity damage to about sixty special form sources (ISO2919 C 63322), leakage of Cs-137 from a supposed insoluble refractory active content (caesium silicoaluminate), and contamination of applicators, floors and bedding. When the situation was detected by means removal contamination tests, after routine inspections, the sources were removed from the hospitals, decontaminated by means of immersion in 3% EDTA solution in ultrasonic bath, subjected to leaking assessment tests, and the ones that passed were placed in low cost stainless steel source holders, designed and built by the instituto Venezolano de Investigaciones Cientificas (IVIC) returned to the hospitals. The leaking sources were removed from use and considered radioactive waste. In order to avoid the occurrence of similar situations, all the importers of such sources are now required to send them to IVIC for testing and placement in proper source holders, before they are shipped to the hospitals. (author)

  15. Maternal and Infantile Metabolism of Caesium

    International Nuclear Information System (INIS)

    Investigations concerning the caesium metabolism of three women from late pregnancy to some months after partus are reported. In two cases, biological half-times of about 30 d are found, in contrast to the half-times usually found of about 70 d. The transfer of activity from mother to child via placenta and later via breast milk has been investigated in the three cases. The specific activity of the infant was, at partus, close to that of its mother. A biological half-time for caesium in children of only 25 d was obtained in two cases. Both caesium-137 and caesium-132 were used for the investigations. The radiation doses to the subjects from these isotopes were very small and comparable with the monthly doses from body potassium. Some conclusions on the possibilities of future work are presented. (author)

  16. Contamination of pork by caesium radioisotopes

    International Nuclear Information System (INIS)

    A dynamic compartmental model for assessment of caesium transport from pigs' feed to pork has been constructed using the food chain monitoring data obtained in Czechoslovakia after the Chernobyl accident. The model is described by a set of linear first-order differential equations, the solution of which provides reliable information on the kinetics of caesium metabolism in pigs, including its retention and degree of resorption through the gastrointestinal tract wall into blood. (author)

  17. Transfer of atmospheric caesium to agricultural products

    International Nuclear Information System (INIS)

    A huge quantity of radioactive rubble was generated by the Great East Japan Earthquake. The Japanese government is considering incineration processing of such rubble in waste incinerators which have suitable equipment, and the government is urged to manage appropriately the radiation exposure of residents living in the vicinity of incinerators by inhalation and ingestion of food. In this study, we developed a model describing plant uptake of atmospheric caesium by direct deposition and root-absorption via soil. Analysis using our model has suggested that wet deposition contributes to transfer to a plant most, when caesium exists in the atmosphere. (author)

  18. Caesium-137 Chloride Retention following Accidental Ingestion

    International Nuclear Information System (INIS)

    Four men became contaminated with caesium-137 chloride due to leaks in a 100 c source. The source was believed to be completely leak proof, since the caesium chloride was contained in a welded stainless-steel capsule which was covered with an outer steel jacket of standard Oak Ridge design. Most of the contamination occurred while the men were cleaning the components of a pneumatic device used to move the source. The most heavily- contaminated individual placed his mouth over the end of a transport tube and attempted to blow some ''dust'' out of the tube. The other men handled various parts of the transport mechanism and wiped ''dust'' out of holes with their fingers. None of the men washed their hands before eating lunch. When radioactive contamination was discovered on the following day, immediate efforts were made to decontaminate the men. Arrangements for whole-body counts were also made and, on the fifth day following contamination, the men reported to the Radiation Exposure Evaluation laboratory. The body burdens on the fifth day ranged from 35 - 970 nc of caesium-137. During the next five to six days the burdens dropped rapidly and on the eleventh day ranged from 28- 780 nc. After the eleventh day the body burdens of caesium-137 changed much more slowly. Whole-body counts made between the 11th and 160th day yielded biological half-lives of 76, 95 and 126 d for the three most heavily-contaminated individuals. During the period of rapid excretion all urine and faeces were collected and counted. These counts indicated a considerable superficial contamination prior to the eleventh day since only a portion of the removed caesium-137 was found in the urine and stool specimens. The body burdens of the four men are compared with normals of the same size, build, age and diet habits. A short discussion of normal burdens is included. A brief description of the counting system, data handling techniques and calibration procedures is also included. (author)

  19. Adiabatic and isothermal compressibility in the liquid state

    International Nuclear Information System (INIS)

    The paper reviews the work carried out on the adiabatic and isothermal compressibility of liquid alkali metals. Saturated liquid states are discussed, including thermodynamic relations, adiabatic compressibility and isothermal compressibility. Results for the compressibility, and other related quantities, for the saturated liquids: lithium, potassium, rubidium, caesium and sodium, over the temperature range approx.= 300 - 18000 K, are presented. Subcooled liquid states are also examined with respect to its thermodynamic relations, and compressibility results (and other related quantities) for the same elements are given. An assessment of errors and data reliability is briefly discussed. (U.K.)

  20. Structure of caesium disulfate at 120 and 273 K

    DEFF Research Database (Denmark)

    Ståhl, Kenny; Berg, Rolf W.; Eriksen, Kim Michael; Fehrmann, Rasmus

    2009-01-01

    The crystal structures of Cs2S2O7 at 120 and 273 K have been determined from X-ray single-crystal data. Caesium disulfate represents a new structure type with a uniquely high number of independent formula units at 120 K: In one part caesium ions form a tube surrounding the disulfate ions, [Cs8(S2...

  1. Treatment of solutions of fission products - Separation of caesium-137

    International Nuclear Information System (INIS)

    For the industrial recovery of caesium-137 from solutions of fission products, the authors utilized the analytical method for determination of caesium by dipicrylamine, adapting it to use on an industrial scale and to the high level of the activities encountered. The process recommended makes it possible both to isolate caesium as a chloride and to recover the precipitation reagent, in one and the same operation. A basic method is suggested. The authors studied the effect of radiation on dipicrylamine and its compounds, this effect proving to be practically nil for solid compounds and negligible for their solutions. The entrainment of caesium by ammonia ion was also studied. The advantages of the proposed process are : high decontamination of the caesium, simple operation and free recycling fo the reagent, high yield for caesium recovery and for dipicrylamine, considerable concentration of caesium activity, operation at room temperature and possibility of continuous operation. By this process caesium can be recovered before certain fission products are eliminated. (author)

  2. Measurement of Caesium-137 in the Normal Person

    International Nuclear Information System (INIS)

    During the period June 1959 to October 1963 the Landstuhl whole-body counter has measured the caesium-137 content of more than 15 000 normal persons. The monthly averages of these measurements indicate a steady increase In the caesium-137 content since June 1962. This increase has become more rapid during the period June 1963 to October 1963. A further evaluation of the monthly averages since June 1962 indicates a mean biologic half-life of caesium-137 of 140 d for persons older than 22 yr. A comparison of the mean caesium-137 content of persons between 8 and 17 yr of age with those older than 22 appears to indicate that the biologic half-life of caesium-137 is shorter in the younger people. This is in agreement with earlier data from this counter concerning measurements of caesium-137 content between June 1959 and December 1960: these data showed a lower caesium-137 content in children than in adults. Another evaluation of recent data from this unit concerns the standard deviation (sigma) of the caesium-137 content in a large population. From this population the sigma of measured caesium/g body potassium values is 33%. This is more than twice the sigma of the body potassium content of this same population. By comparing a group of persons who have undergone several repeat assays over an extended period of time with the monthly means of the total population measured, it has been found that the large sigma of caesium-137 content cannot be caused solely by the varying diets of the population measured. (author)

  3. Caesium dosing reduces uptake of radiocaesium by sheep

    International Nuclear Information System (INIS)

    In sheep grazing pasture contaminated by radiocaesium, administration of stable caesium was found to inhibit the uptake of radiocaesium. Eight lambs feeding on a contaminated pasture received an oral dose of 500 mg CsCl and after 6 days had a radiocaesium load 17% lower than that of a control group on the same pasture. The rate of radiocaesium excretion from 4 lambs, in metabolism cages and fed uncontaminated grass, was unaffected by CsCl dosing in comparison with controls. Thus, caesium dosing appeared to inhibit uptake but did not alter rates of caesium loss by normal processes of metabolism. Measurements of stable and radioactive caesium excretion rates were interpreted using a compartment model, based on the hypothesis of two major caesium reservoirs within the sheep, with derived biological half-lives approximately 4 and 25 days, and capacities 20 and 80% of total, respectively. Caesium dosing appeared to saturate the latter reservoir and consequently inhibit further uptake. If a practicable method of application could be achieved, caesium dosing could be useful in the management of sheep and other grazing animals on radiocaesium-contaminated pasture and could find application to radiological protection in humans. (Author)

  4. Studies of Sorption and Migration of Radioactive Elements in Soils

    International Nuclear Information System (INIS)

    The paper presents the results of investigations into the sorption and migration of radioelements during radioactive filtering flow through the soil. For this purpose the authors used the types, of sand, oi average coarseness and effective porosity, which are to be found widely disseminated throughout the central belt of the Soviet Union. It is shown that the sorption of strontium and caesium take place separately and that the capture of caesium by soils is an irreversible process. It is also shown that sorption processes inhibit the filter-diffusion process at low diffusion rates and that die strontium movement is 40-60 times slower than the filtering and the caesium movement 100 times slower. Trials were made with a method of calculating the basic kinetic parameters of sorption, thus making it possible to characterize the movement of radioactive strontium and describe the migration of radioactive caesium. (author)

  5. Determination of caesium-137 in fast-reactor coolant systems.

    Science.gov (United States)

    Oldham, G; Ware, A R; Sykes, D J

    1969-03-01

    A method for the separation of caesium by ion-exchange involving ammonium 12-molybdophosphate has been investigated, and found to be 100% efficient for aqueous solutions with high sodium and potassium concentrations. PMID:18960518

  6. Sorption of caesium and strontium onto calcium silicate hydrate in saline groundwater

    International Nuclear Information System (INIS)

    Full text of publication follows: In the concept for radioactive waste disposal in Japan, cement is a potential waste packaging and backfilling material and is expected to provide chemical containment. The sorption of radionuclides onto cement materials, which controls the aqueous concentrations of elements in the pore-water, is a very important parameter when considering the release of radionuclides from the near field of a cementitious radioactive waste repository. Many safety assessment calculations currently assume radionuclide retardation as linear sorption equilibrium and describe it with a distribution ratio (Rd value). In this study, the sorption mechanism is discussed by measuring the sorption isotherm of caesium, strontium (10-5 ∼ 10-2 mol dm-3) and sodium (10-4 ∼ 10-1 mol dm-3) onto Calcium Silicate Hydrate (C-S-H gel, Ca/Si 0.65 ∼ 1.2) at a liquid:solid ratio of 100:1, to support the assumption. In addition, the competitive sorption between caesium or strontium, and sodium is studied by sorption measurements using a range of sodium chloride concentration to simulate different ionic strengths in saline groundwater. The initial and equilibrated aqueous compositions were measured in the sorption experiments and it was found that caesium, strontium and sodium were sorbed by substitution for Ca in C-S-H phases by examining the mass balance. Based on the experimental results, we propose a modelling approach in which the ion-exchange model is employed and the presence of some calcium sites with different ion-exchange log K values in C-S-H is assumed by considering the composition and the structure of C-S-H. The modelling calculation results predict the measured Rd values well and also describe the competition of sorption of caesium or strontium, and sodium in the experiments. The log K values for sorption of each cation element decreased as Ca/Si ratio of C-S-H gel increased. This agrees with the trend that C-S-H gel is negatively charged at low Ca

  7. Influence of herbivory on caesium turnover in a forest ecosystem

    International Nuclear Information System (INIS)

    The effect of herbivory by bank vole (Clethrionomys glareolus) and moose (Alces alces) in relation to litterfall in a boreal forest is analysed. The main purpose is to estimate the relative importance of these processes for the transfer of caesium-137 to soil. Biomasses of litterfall and food consumption were selected from different forest biotopes. The analysis of the input and output of caesium-137 in the vole and moose populations is based on mass balance calculations for caesium-137 in steady state conditions. From this assessment, herbivory appears to be within an order of magnitude of litterfall. With due regard to the lower caesium level in litterfall than in living plant tissue, transfer of radioactive caesium by herbivory is seen to be even higher in comparison to that by litterfall, than apparent from the corresponding transfer of organic matter. In addition, the availability of caesium-137 from animal excrements is expected to be high and fast, which further emphasises the relative importance of herbivory in feed-back from vegetation to soil

  8. Project Caesium - An ion exchange model for the prediction of distribution coefficients of caesium in bentonite

    International Nuclear Information System (INIS)

    A surface chemical model is established to thermodynamically describe caesium sorption on bentonite. Caesium sorption is studied on Wyoming bentonite MX-80 in solutions of NaCl, KCl, MgCl2, CaCl2, NaNO3 and Ca(NO3)2 of concentrations varying between 0.025M and 1M, as well as in the weakly saline Allard groundwater and the strongly saline Aespoe groundwater. Based on these experiments it is shown that the sorption behaviour of caesium on bentonite can be described, within the experimental and model uncertainties, in terms of a one-site ion exchange model. The ion exchange constant for the replacement of Na+ on montmorillonite by Cs+ is logKex degrees = 1.6. The model predictions compare well with sorption data published in the open literature on both Wyoming bentonite MX-80 and other types of bentonite. For the analysis of diffusion experiments in compacted bentonite, the apparent diffusivity of tritiated water, HTO, is used as an analogue to estimate the pore diffusivity of Cs+. Since insufficient information is available at present to estimate the porosity actually available for diffusion in compacted bentonite, it is assumed that the diffusion porosity can be approximated by using the value of the bulk porosity. Under these circumstances, the cation ex change capacity (CEC) found to be available for the diffusing species in compacted bentonite corresponds to about 12% of the total CEC of bentonite. It is recognised that the errors made in the estimation of the pore diffusivity and of the diffusion porosity are contained in the reduction factor of the CEC. A discussion of the factors affecting the diffusivities of radionuclides and the problem of establishing consistent sets of diffusivity data is given in the Appendix. 33 refs, 7 figs, 12 tabs

  9. Note on Two Types of Contamination of Human Beings by Caesium-137

    International Nuclear Information System (INIS)

    The authors present an elimination curve for a case of occupational contamination by caesium-137. They also show how the caesium-137 body burden varied during 1963 in a group of persons who did not undergo occupational exposure. (author)

  10. Simultaneous resolution of reactive radioactive decay, non-isothermal flow, and migration with application to the performance assessment for HLW repositories

    International Nuclear Information System (INIS)

    Radioactive decay is an important subject to take into account when studying the thermo-hydro-dynamic behavior of the buffer clay material used in the containment of radioactive waste. The modern concepts for the multibarrier design of a repository of high level waste in deep geologic formations consider that once canisters have failed, the buffer clay material must ensure the retention and/or delay of radionuclides within the time framework given in the assessment studies. Within the clay buffer, different chemical species are retarded/fixed according to several physicochemical processes (ion exchange, surface complexation, precipitation, matrix diffusion,..) but typical approaches do not consider the eventuality that radioactive species change their chemical nature (i.e. phase) thereby affecting their reactive behavior. The radioactive decay of an element takes place independently of the phase (aqueous, solid or gaseous) to which it belongs. This means that, in terms of radionuclide fixation, some geochemical processes will be effective scavengers (for instance mineral precipitation of crystal growth) while others will not (for instance ion exchange and/or sorption). In this contribution we present a reactive radioactive decay model of any number of chemical components including those that belong to decay series. The model, which is named FLOW-DECAY, also takes into account flow and isotopic migration and it has been applied considering a hypothetical model scenario provided by the project ENRESA 2000 and direct comparison with the results generated by the probabilistic code GoldSim. Results indicate that FLOW-DECAY may simulate the decay processes in a similar way that GoldSim, being the differences related to factors associated to code architecture. (orig.)

  11. Human metabolism of caesium[Radioecology

    Energy Technology Data Exchange (ETDEWEB)

    Raeaef, C.L. [Lund Univ., Malmoe Univ. Hospital, Dept. of Radiation Physics, Malmoe (Sweden); Falk, R. [Swedish Radiation Protection Authority, Stockholm (Sweden); Rahola, T. [STUK - Radiation and Nuclear Safety Authority, Helsinki (Finland); Lauridsen, B.; Soogaard-Hansen, S. [Risoe National Lab., Roskilde (Denmark); Skuterud, L. [NRPA - Norwegian Radiation Protection Authority, Oesteraes (Norway)

    2006-04-15

    A study of the human biokinetics of caesium in two forms, i.) incorporated in foodstuff ({sup 137}Cs in perch and mushrooms) and ii.) in ionic state ({sup 134}Cs in aqueous solution) has been carried out at the department of Radiation Physics in Malmoe, starting in 2001. The results of the pilot study was published in 2004, and a continuation of that study is now undertaken by means of NKS funding (NKS-B Cskinetik). The aim is to, i.) investigate whether Scandinavian populations exhibit shorter biological half-time of radiocaesium than other populations; ii.) extend the biokinetic study to additional human subjects from the other Nordic countries. Results from the continued study further indicate a near complete absorption of radiocaesium in the gastro-intestinal tract, be it in ion state or contained in food matrix. So far, the literature survey of Nordic studies on biokinetics of Cs does not suggest that the biological half-time is shorter among Scandinavians, although there is a considerable variation between individuals. (au)

  12. Distribution coefficients of caesium, chlorine, iodine, niobium, selenium and technetium on Olkiluoto soils

    International Nuclear Information System (INIS)

    Retention of caesium, chlorine, iodine, niobium, selenium and technetium was investigated on soil samples from Olkiluoto using laboratory batch sorption experiments. Distribution coefficients were measured for both dried and sieved and untreated (wet, not sieved) mineral soil and humus in aerobic and anaerobic conditions. Mineralogical composition of the samples was determined by XRD-analysis. Caesium was sorbed efficiently on mineral soil samples and less efficiently on humus. Sorption decreased with decreasing cation exchange capacity and clay fraction content. The effect of competing cations decreased in the order Cs+>NH4+>K+>Ca2+>Na+. Chlorine was not retained by mineral soil samples, and the sorption was weak on humus. The sorption of iodine was the strongest on humus and the weakest on the untreated mineral soil samples in the anaerobic conditions. In the mineral soil samples, the sorption decreased with decreasing organic matter content and increasing pH. The retention of niobium on soil samples was the most efficient among the studied elements. The retention was high regardless of the aeration conditions. Sorption on humus was smaller. Selenium was retained efficiently on humus. Sorption on mineral soil samples was stronger in aerobic conditions. Sorption increased with time. Technetium was sorbed well on humus and anaerobic, untreated mineral soil samples. Sorption increased with increasing organic matter content and decreasing redox potential. The results from the sorption experiments are used in the site specific radionuclide migration modelling. (orig.)

  13. Retention capacity of the calcium silicates hydrates (CSH) for caesium

    International Nuclear Information System (INIS)

    Alkalis are poorly trapped by cement and this constitutes one of the problem for the use of cement as nuclear waste matrix. Therefore we have studied the sorption of 137Cs on the CSH which are the major components of a Portland cement. CSH of different Ca/Si has been synthetised in suspension. Caesium chloride, which is highly soluble, was placed in a reactor with the CSH. To have a high precision for the caesium quantity fixed by the CSH, radioactive caesium was used as tracer. We observed that the maximum exchange capacity occurs at low Ca/Si ratio, when the structure is close to that of tobermorite. A Cs/Ca molar ratio around one could be obtained in this structure. (orig.)

  14. The utilization of caesium 137 in studying soil degradation

    International Nuclear Information System (INIS)

    The caesium 137 isotope is distributed in the atmosphere during nuclear explosions, and is absorbed in the upper horizons of the soil on reaching the ground. When it is incorporated in the fine fraction of the soil, caesium 137 measurement allows movements affecting cultivated lands (mass movements, runoff effects, wind action) and rate of soil degradation over half a century to be evaluated. Vegetal cover and techniques of soil utilization must be considered; this method has been tested on a watershed in the Parisian Basin. 5 figs., 26 refs

  15. Caesium fallout as a tracer of erosion-sedimentation

    International Nuclear Information System (INIS)

    The purpose of this paper is to set up a methodology of use of radioactive caesium fallout, to measure erosion and sedimentation in a sub-catchment and to establish the effects of geomorphological parameters, land uses and soil nature, on the losses caesium by physical process. The result obtained by this new and elegant approach, on a watershed of 4114 ha., studied before by classical and conventional techniques, gives a good evaluation of erosion, but also sedimentation rate, and permit to stand up, a model and sampling strategy, to extend the method to large catchment. 1 tab., 2 refs. (author)

  16. The mechanisms of caesium uptake by plants

    International Nuclear Information System (INIS)

    Persistent radioactive isotopes of caesium (134Cs and 137Cs) in the environment are of concern because they impact on both health and commerce. They enter the terrestrial food chain through plants. Plant roots take up Cs+ from the soil solution. To reach the shoot via the xylem, Cs+ must cross the plasma membranes of root cells at least twice. This is catalysed by transport proteins. Since Cs is an alkali metal with chemical properties similar to potassium (K), it has been suggested that the same proteins that transport K+ also transport Cs+. However, the Cs:K ratio in the shoots of different plant species grown under identical conditions varies widely. Since different transport proteins have contrasting abilities to discriminate between Cs+ and K+, this varying Cs:K ratio suggests that a different complement of transport proteins operates in different plant species. In the plasma membrane of root cells inward-rectifying K+ channels (KIRCs), outward-rectifying cation channels (KORCs and NORCs), voltage-independent cation channels (VICCs) and voltage-dependent Ca2+ channels (HACCs and DACCs) are all permeable to Cs+ and K+. In addition, the 'high-affinity' K+/H+ symporters (KUPs) and 'low affinity' transporters, such as the wheat TaLCT1 protein, may also transport Cs+ and K+. The relative abundance and selectivity of these transport proteins in the root plasma membrane will determine the relative fluxes of Cs+ and K+ to the shoot. Theoretical models describing Cs+ fluxes across the plasma membrane of root cells predict that, under natural conditions, VICCs mediate most (30 to 90%) of the Cs+ influx, with KUPs mediating the remainder, Cs+ influx through KIRCs is negligible, and stelar KORCs load Cs+ into the xylem. These predictions are consistent with the identical pharmacology of VICCs and Cs+ uptake by plants, which are both partially inhibited by La3+, Ba2+ or Ca2+ at millimolar concentrations, and the phenotypes of Arabidopsis mutants lacking the dominant root

  17. Elements of reflection on pathologies possibly induced by caesium 137

    International Nuclear Information System (INIS)

    The author discusses the content of few known publications on the possible pathological effects of caesium 137: a Belarus study on the consequences of Chernobyl, results of few autopsies performed on babies and adults, a study performed on rats, and a study performed on a set of 94 children in a sanatorium

  18. Low Level Caesium Mapping in Latvia Anno 1995

    DEFF Research Database (Denmark)

    Aage, Helle Karina

    1999-01-01

    In Latvia the caesium-137 contamination from the Chernobyl accident and from the nuclear weapon tests in the 1960´es is very low. Conventional techniques for extracting information from the measured spectra cannot be used here. Therefore a new, sensitive technique - the pseudo concentration method...

  19. Low Level Caesium Mapping in Latvia Anno 1996

    DEFF Research Database (Denmark)

    Aage, Helle Karina

    1999-01-01

    In Latvia the caesium-137 contamination from the Chernobyl accident and from the nuclear weapon tests in the 1960´es is very low. Conventional techniques for extracting information from the measured spectra cannot be used here. Therefore a new, sensitive technique - the pseudo concentration method...

  20. The Effect of Chlorothiazide on Caesium-137 Excretion in Human Subjects

    International Nuclear Information System (INIS)

    The present study was carried out to determine factors that influence caesium metabolism in normal human subjects with particular interest in finding a therapeutic regimen for reducing the body burden of caesium. Since caesium and potassium are chemically similar, and are both localized in the intracellular compartment of the body, principally in muscle, it seemed possible that chlorothiazide, which has a marked potassium diuretic effect, might also increase caesium excretion. Four normal subjects were given a single dose of 0.1 μc of caesium-137 by mouth. Two subjects were given chlorothiazide 2.0 g/d for a total of three consecutive days starting 1 h after the caesium intake. The chlorothiazide dose was repeated at two weeks. The other two subjects were used as controls. The body burden of caesium-137 was measured by a whole-body counter at intervals up to 320 d. Daily urine collections were made for three control days and 20 d following caesium intake. The samples were analysed for electrolytes and caesium activity. Although chlorothiazide increased K excretion to 1. 5 times the control values, it had no significant effect on caesium excretion or in reducing the body burden of caesium. In all subjects a small fraction of caesium (10-20%) was excreted rapidly with a biological half-life (T),) of less than 1 d. The remainder was excreted at a constant rate with Tb of 90 to 155 d. More than 70% of the caesium eliminated from the body per day was excreted by the kidney. Tb of K was also calculated by the formula TbK = Total body K/Urine K x 0,693 x 0,8 assuming 80% of the total potassium excreted is by kidney. Tb of K was 35 to 42 d. The discrimination ratio TbCs/TbK was 2.1 to 3.8. These results demonstrate that caesium and potassium are not utilized interchangeably. Caesium is retained preferentially over potassium and changes in potassium turnover have no effect on caesium turnover. Studies are being carried out at the present time to determine the effect of

  1. Study of caesium adsorption on hydrated calcium-silicate-aluminate systems

    International Nuclear Information System (INIS)

    Immobilization of caesium in cementitious matrixes was studied in the present paper which is a key issue of handling radioactive caesium containig wastes for caesium does not form stabile compounds therefor it can not be readily immobilized. Model matrices were prepared to map up the calcium-silicate-aluminate system considering caesium immobilization, which were of different starting compositions. To caracterize Cs sorption, distribution ratios were determined. Based on the results obtained the model matrix compositions were prepared using industrial grade materials and their caesium retardation and trapping were examined by means of leaching and sorption experiments. In the light of the results obtained, it can be established that immobilization of caesium significantly depend on the starting composition of the used matrix. (orig.)

  2. Chernobyl caesium distribution in two forest soils

    International Nuclear Information System (INIS)

    The Chernobyl nuclear accident on April 26, 1986 affected a considerable part of Europe, including the Romanian territory too. The soil acts as an integrator and the main part of the received radionuclides remains here. However, due to diffusion, leaching and runoff, activity of living organisms in soil, human activity and different other factors, the deposited radionuclides on the soil surface can be removed from the original deposition areas. Mainly, the transport of Cs-137 from soil to other environmental factors is intensively studied having in view the natural resource exploitation in radioactive contaminated areas, this radionuclide being one of the most important radioisotopes released by earlier nuclear weapon tests and nuclear accidents. Generally, migration rates of radionuclides in soil are evaluated by column and percolation experiments, in controlled conditions and using well-defined concentrations of the radionuclide. As part of the environment, the forests have been contaminated up to a depth of 30 cm by the radionuclides resulting from Chernobyl nuclear accident. As the forest is a source of radionuclides for intake and habitat for some critical groups and also a secondary source of contamination (resuspension, erosion), its radioecology became an increasing research topic. The depth distribution of radiocaesium was analysed in the brown-reddish forest type soil of two forests. The depth profile and the specific activity of each layer permit the assessment of total deposition, migration rate and diffusion coefficient for Cs-137 and Cs-134. The total deposition of Cs-137 is about 47 kBq/m2 for Magurele area and about 14 kBq/m2 for Naipu forest. The migration rate is more than 10 times higher in Naipu forest as compared to Magurele forest. The diffusion coefficients are similar, namely about 0.2 cm2/year. (authors)

  3. Reduction of radioactive caesium in meat and fish by soaking

    Energy Technology Data Exchange (ETDEWEB)

    Petaejae, E.; Puolanne, E. (Helsinki Univ. (Finland). Dept. of Meat Technology); Rantavaara, A.; Paakkola, O. (Finnish Centre for Radiation and Nuclear Safety (STUK), Helsinki (Finland))

    1992-01-01

    The removal of radioactive caesium from meat by soaking in brine or water and the effect of injection curing, temperature, size of meat piece and cooking on this removal were studied. The availability of the brined meat for the manufacture of cured, smoked and cooked meat, oven-cooked meat and cooked sausages was also investigated. The soaking method was also tested on fish. (Author).

  4. Modelling of caesium deposition in CAGR reactor circuits

    International Nuclear Information System (INIS)

    A laboratory rig at BNL has been used to measure the deposition of radiocaesium in a CO2 gas stream onto steel surfaces in a thermal gradient furnace. The results of these measurements show that at high temperatures the deposition can be described by a model in which caesium diffuses into and out of the oxide film on the steel surface, with an evaporation boundary condition at the gas-oxide interface. A simple version of the model gives the deposition rate (dN)/dt = ngAot1/2 where ng is the concentration of caesium in the gas and Ao, the 'absorptivity', is a property of the surface. At low temperatures (below about 300 deg. C), caesium was retained by the surface. More recently, the experimental programme has been extended to cover deposition on graphite surfaces. Results show that significant retention takes place at temperatures typical of the cooler region of a CAGR circuit, although desorption is rapid at higher temperatures. A computer programme, CAESAR3, has been written to apply this model to the circuit of a CAGR. The programme handles a flexible set of parameters and can accommodate changing temperatures, pressures, flow rates, leak rates and source terms in a circuit which may have two interconnected branches. Measurements have been made of caesium distributions in the boilers of the Windscale prototype AGR and in the Hinkley Point 'B' CAGR. The results obtained are broadly in agreement with the model, although there are a number of apparent differences. Possible reasons for these are discussed. (author)

  5. Bichromatic State-insensitive Trapping of Caesium Atoms

    OpenAIRE

    Metbulut, M. M.; Renzoni, F.

    2015-01-01

    State-insensitive dipole trapping of multilevel atoms can be achieved by an appropriate choice of the wavelength of the trapping laser, so that the interaction with the different transitions results in equal AC Stark shifts for the ground and excited states of interest. However this approach is severely limited by the availability of coherent sources at the required wavelength and of appropriate power. This work investigates state-insensitive trapping of caesium atoms for which the required w...

  6. Distribution of Caesium-137 in Samples Consisting of Soft Tissue, Bone and Bone Marrow

    International Nuclear Information System (INIS)

    The investigations which were performed up to now on the distribution of-caesium-137 in the human organism could not explain exactly the distribution of the radiocaesium between bone and bone marrow. That is why a reliable estimation of the radiation burden of the skeleton caused by the incorporation of atmospheric caesium-137 is not given in the literature. Therefore, the concentration of caesium-137 in compact bones as well as in bone marrow was determined. Furthermore, the concentration of caesium-137 in the soft tissue of the same individuals was measured. (author)

  7. Interdigitated electrode array based sensors for environmental monitoring of caesium

    Energy Technology Data Exchange (ETDEWEB)

    Nickson, I D [John Tyndall Nuclear Research Institute and Centre for Materials Science, University of Central Lancashire, Preston PR1 2HE (United Kingdom); Boxall, C [Engineering Department, Lancaster University, Lancaster LA1 4YR (United Kingdom); Port, S N, E-mail: c.boxall@lancaster.ac.uk [DSTL, Salisbury, Wiltshire SP4 0JQ (United Kingdom)

    2010-03-15

    The requirement for on-line and in-situ monitoring of analytes in process and effluent streams and in ground waters has become increasingly more important in recent years. We therefore describe the development of the transduction element for a fully automated online instrument for the detection of caesium. The sensor layer for this instrument employs an Ion Selective Conductimetric Microsensor (ISCOM) as the detector. This is based upon a plasticized polymeric membrane incorporating a selective ionophore, overlaying two interdigitated microelectrode arrays. A direct relationship has been observed between the bulk conductance (as determined by the microelectrodes) of the ionophore loaded membrane and the concentration of the primary ions in solution. Caesium selective ISCOMs were prepared using an ion selective membrane containing the commercially available ionophore Calix [6]arene-hexaacetic acid hexaethyl ester, polyvinylchloride (PVC) and plasticiser Nitrophenylether (NPOE). The relative levels of membrane components have also been varied in order to further enhance the ISCOM response. We also present preliminary data concerning the caesium selectivity with respect to a range of possible interferents, including rubidium.

  8. Interdigitated electrode array based sensors for environmental monitoring of caesium

    Science.gov (United States)

    Nickson, I. D.; Boxall, C.; Port, S. N.

    2010-03-01

    The requirement for on-line and in-situ monitoring of analytes in process and effluent streams and in ground waters has become increasingly more important in recent years. We therefore describe the development of the transduction element for a fully automated online instrument for the detection of caesium. The sensor layer for this instrument employs an Ion Selective Conductimetric Microsensor (ISCOM) as the detector. This is based upon a plasticized polymeric membrane incorporating a selective ionophore, overlaying two interdigitated microelectrode arrays. A direct relationship has been observed between the bulk conductance (as determined by the microelectrodes) of the ionophore loaded membrane and the concentration of the primary ions in solution. Caesium selective ISCOMs were prepared using an ion selective membrane containing the commercially available ionophore Calix [6]arene-hexaacetic acid hexaethyl ester, polyvinylchloride (PVC) and plasticiser Nitrophenylether (NPOE). The relative levels of membrane components have also been varied in order to further enhance the ISCOM response. We also present preliminary data concerning the caesium selectivity with respect to a range of possible interferents, including rubidium.

  9. Interdigitated electrode array based sensors for environmental monitoring of caesium

    International Nuclear Information System (INIS)

    The requirement for on-line and in-situ monitoring of analytes in process and effluent streams and in ground waters has become increasingly more important in recent years. We therefore describe the development of the transduction element for a fully automated online instrument for the detection of caesium. The sensor layer for this instrument employs an Ion Selective Conductimetric Microsensor (ISCOM) as the detector. This is based upon a plasticized polymeric membrane incorporating a selective ionophore, overlaying two interdigitated microelectrode arrays. A direct relationship has been observed between the bulk conductance (as determined by the microelectrodes) of the ionophore loaded membrane and the concentration of the primary ions in solution. Caesium selective ISCOMs were prepared using an ion selective membrane containing the commercially available ionophore Calix [6]arene-hexaacetic acid hexaethyl ester, polyvinylchloride (PVC) and plasticiser Nitrophenylether (NPOE). The relative levels of membrane components have also been varied in order to further enhance the ISCOM response. We also present preliminary data concerning the caesium selectivity with respect to a range of possible interferents, including rubidium.

  10. The removal of caesium ions using supported clinoptilolite.

    Science.gov (United States)

    De Haro-Del Rio, D A; Al-Jubouri, S; Al-Joubori, S; Kontogiannis, O; Papadatos-Gigantes, D; Ajayi, O; Li, C; Holmes, S M

    2015-05-30

    In this paper, the sorptive kinetic and diffusional characteristics of caesium ion removal from aqueous solution by carbon-supported clinoptilolite composites are presented. Natural clinoptilolite was supported on carbonaceous scaffolds prepared from date stones. Thermal treatment was applied to produce voids in the carbon which was conditioned using polydiallyldimethylammonium chloride to facilitate the clinoptilolite attachment. This method allowed the formation of a consistent zeolite layer on the carbon surface. The composite was applied in the removal of non-radioactive caesium ions showing an enhanced uptake from 55 mg g(-1) to 120.9 mg g(-1) when compared to clinoptilolite. Kinetic studies using Pseudo First Order model revealed an enhanced rate constant for carbon-clinoptilolite (0.0252 min(-1)) in comparison with clinoptilolite (0.0189 min(-1)). The Pseudo-First Order model described the process for carbon-clinoptilolite, meanwhile Pseudo Second Order model adjusted better for pure clinoptilolite. Diffusivity results suggested that mass transfer resistances involved in the Cs(+) sorption are film and intraparticle diffusion for natural clinoptilolite and intraparticle diffusion as the mechanism that controls the process for carbon-clinoptilolite composite. The most significant aspect being that the vitrified volume waste can be reduced by over 60% for encapsulation of the same quantity of caesium due to the enhanced uptake of zeolite. PMID:25702634

  11. The behaviour of radioactive caesium in a boreal forest ecosystem

    International Nuclear Information System (INIS)

    The distribution of radioactive caesium (Cs-134 and Cs-137) in a boreal forest ecosystem is studied with focus in the dynamics of the turnover in, and loss from, the system. Measurements of the distribution in soil and vegetation, as well as the loss of radioactive caesium by run-off from a catchment, constitute the basis for an analysis of the caesium budget in the system. Comparisons of the distribution of 'old' Cs-137, i.e. originating from fallout due to the atmospheric nuclear weapons test, and that due to deposition after the accident in Chernobyl 1986 are used for extrapolations to future situations concerning transport of Cs-137 via the food chains over berries and moose to man. The exposure in a long term perspective due to the average intake of Cs-137 in the Swedish population by consumption of meat, milk, and milk products (i.e. of an agricultural origin) is compared to that due to ingestion of the forest products: berries (bilberry, lingonberries, and cloudberries) and moose meat. (au) (34 refs.)

  12. Chernobyl caesium distribution in two forest soils

    International Nuclear Information System (INIS)

    The Chernobyl nuclear accident on April 26, 1986, affected a considerable part of Europe, including the Romanian territory too. As part of the environment, the forests, covering up to 30 % area of Romania, were contaminated by the radionuclides resulting from Chernobyl nuclear accident. Being a source of radionuclides for intake and habitat for some critical groups and also a secondary source of contamination (resuspension, erosion), forest radioecology is an increasing research topic. The distribution of radiocaesium with depth was analysed in the brown-reddish forest type soil of two forests. The profile with depth and the specific activity of each layer permit the assessment of: total deposition, migration rate and diffusion coefficient for Cs-137 and also Cs-134. The total deposition of Cs-137 is about 47 kBq/m2 for Magurele area and about 14 kBq/m2 for Naipu forest. The migration rate is more than 10 times greater in Naipu forest as in Magurele forest. The diffusion coefficients are similar, about 0.2 cm2/an. (author)

  13. Caesium absorption by barley - influence of its retention by the soil - competitive action of potassium

    International Nuclear Information System (INIS)

    We have studied, in various culture media, how the absorption of caesium by barley varies with its concentration, and how this absorption can be in competition with a similar alkali cation-potassium. We have also considered the caesium distribution in the ground in particular radio-active caesium, between the soil and solution, as a function of the amount of caesium. From our work it is clear that barley behaves very differently according to whether the caesium is in a nutritive solution or is in the soil: for a nutritive solution, the fraction of caesium (radioactive and stable) absorbed by barley remains practically constant in the presence of increasing amounts (relatively small) of stable caesium; in soil, the fraction of the radio-active caesium absorbed increases as the stable caesium content (fairly low) of the soil increases, in relationship with a rapidly decreasing selectivity of the soil for Cs+. The difference between these results is thus explained by the very pronounced selectivity of the illitic soil studied for Cs+, as long as the proportion of Cs remains low, about as low as that of most natural soils. Furthermore, the K+ ion is in competition with the Cs+ ion, for absorption by barley in a culture medium in a nutritive solution or in soil, only when the potassium concentrations are relatively low, of the order of the nutritive maximum. This shows that the addition of potassium to a medium already rich in this element does not reduce the absorption of caesium by barley. The choice of experimental conditions close to natural conditions (nutritive media strong in calcium) and the examination of the distribution of radioactive caesium between the soil, the soil solution and the plant in the presence of very low doses of stable caesium make these results interesting from the 'atomic health' point of view; it should be expected that a definite contamination risk exists for plants cultivated on synthetic media and for plants such as rice and cress

  14. Development of electrokinetic remediation for caesium: A feasibility study of 2D electrode configuration system

    Science.gov (United States)

    Syah Putra, Rudy

    2016-02-01

    Agar matrix was artificially contaminated with caesium and subjected to rapid assessment of electrokinetic treatment on the basis of the 2D electrode configuration. The effect of caesium concentration on the process was investigated using different electrode configuration (i.e. rectangular, hexagonal and triangular). During treatment the in situ pH distribution, the current flow, and the potential distribution were monitored. At the end of the treatment, the caesium concentration distribution was measured. The results of these experiments showed that for caesium contamination, pH control is essential in order to create a suitable environment throughout the agar matrix to enable contaminant removal. It was found that the type of electrode configuration used to control the pH affected the rate of caesium accumulation. All of the electrode configurations tested was effective, but the highest caesium extraction was achieved when the hexagonal pattern was used to control the pH. After 72 h of treatment at 50 mA, the concentration of caesium decreased gradually from the second and first layer of agar matrix throughout the cell, suggesting that most of the caesium was concentrated on the cathode part.

  15. Isothermal Containment Module

    Science.gov (United States)

    1999-01-01

    Isothermal Containment Modules are the temperature-controlling carrier that BioServe built to carry Commercial Generic Bioprocessing Apparatus (CGBA) and in the future, Space Automated Bioproduct Lab (SABL) to the International Space Station.

  16. Uptake Evaluation Of Glass house Grown Grasses In Radio phyto remediation Of Caesium-Contaminated Soil

    International Nuclear Information System (INIS)

    A glass house experiment was performed to evaluate the uptake of grasses viz. Napier and Vetiver in radiophytoremediation of caesium-contaminated soil. The glass house radiophytoremediation experiment was designed according to the Randomized Complete Block Design (RCBD). The grasses were grown in troughs filled with soil mixed with a known specific activity of 134Cs. Initial Cs activity and activity after different cultivation time intervals of 1, 3, 6 and 9 months were analyzed using gamma spectrometer direct measurement. The results showed the uptake of caesium by Napier and Vetiver after 9 months with the transfer factors (TF) were 4.70 and 6.25, respectively. Meanwhile, the remediation of caesium from contaminated soil at the same time was 95.25 % (Napier) and 95.58 % (Vetiver). Both grasses have been found to accumulate caesium, with Vetiver accumulating higher than Napier. Thus, the present study suggests that Vetiver could be used as a potential plant for radiophytoremediation of caesium. (author)

  17. A modified version of the combined in-diffusion/abrasive peeling technique for measuring diffusion of strongly sorbing radionuclides in argillaceous rocks: A test study on the diffusion of caesium in Opalinus Clay

    International Nuclear Information System (INIS)

    A filter free diffusion set-up was developed for measuring the diffusion of strongly sorbing radionuclides in indurated argillaceous rocks such as Opalinus Clay (OPA) that normally disintegrate when contacted with a solution. Small bore cores drilled parallel to the bedding plane and embedded in epoxy resin were found to be stable and could be used for performing in-diffusion measurements. The method was tested with the diffusion of caesium, spiked with caesium-134, in Opalinus Clay. The profile of Cs in the clay sample was determined with a modified version of the abrasive peeling technique. The diffusion parameters obtained for caesium were in fair agreement with those determined earlier using the classical through-diffusion technique where stainless steel filters were used to confine the samples. - Highlights: • We developed a simple method to study diffusion of radionuclides in clay rocks. • We tested the method with diffusion of caesium in Opalinus Clay. • The obtained diffusion parameters are in agreement with previous studies. • The proposed technique forms a step forward for migration studies in clay rock

  18. Caesium uptake by Callovian-Oxfordian clayrock under alkaline perturbation

    OpenAIRE

    Gaboreau, Stéphane; Claret, Francis; Crouzet, Catherine; Giffaut, Eric; Tournassat, Christophe

    2012-01-01

    Caesium is one of the main radionuclides present in radioactive waste. 135Cs has a very long half-life (~2.3 106 yr) and Cs is, therefore, one of the main safety relevant elements (Kissane, 2009). For these reasons, Cs is one of the most widely studied radionuclides in environmental sciences. Numerous works have been devoted to developing sorption models enabling the prediction of Cs sorption in clay-rich media. These models consider the presence of different exchange sites at clay surfaces h...

  19. Assessment of the caesium-137 flux adsorbed to suspended sediment in a reservoir in the contaminated Fukushima region in Japan

    International Nuclear Information System (INIS)

    We estimated the flux of caesium-137 adsorbed to suspended sediment in the Kusaki Dam reservoir in the Fukushima region of eastern Japan, which was contaminated by the Fukushima Nuclear Power Plant accident. The amount and rate of reservoir sedimentation and the caesium-137 concentration were validated based on the mixed-particle distribution and a sediment transport equation. The caesium-137 and sediment flux data suggested that wash load, suspended load sediment, and caesium-137 were deposited and the discharge and transport processes generated acute pollution, especially during extreme rainfall-runoff events. Additionally, we qualitatively assessed future changes in caesium-137 and sediment fluxes in the reservoir. The higher deposition and discharge at the start of the projection compared to the 2090s are most likely explained by the radioactive decay of caesium-137 and the effects of reservoir sedimentation. Predictions of the impacts of future climate on sediment and caesium-137 fluxes are crucial for environmental planning and management. - Highlights: • Sediment and caesium-137 fluxes were validated incorporating the effects of extensive reservoir operations. • The sediment and caesium-137 concentrations in a reservoir within a contaminated territory were determined. • The impacts of future projection on suspended sediment and caesium-137 fluxes were qualitatively assessed. - This study estimated the flux of caesium-137 adsorbed to suspended sediment focussing on a major reservoir in the Fukushima region of eastern Japan

  20. Caesium transfer to placenta, urine and human milk

    International Nuclear Information System (INIS)

    After the Chernobyl accident few measurements on radioactive contamination of maternal milk, placenta and urine of nursing mothers were carried out. Two previous studies on breast milk contamination were conducted in different Italian areas by the Physics Department of the National Institute of Health (Laboratorio di Fisica, Istituto Superiore di Sanita). In the first study conducted in collaboration with the Epidemiological Unit of the Lazio District, I-131, Cs-134 and Cs-137 concentrations were measured in mixed breast milk samples pooled from 5-10 women in the first week after delivery, from May 1986 to December 1987, in the Rome area. The second research was conducted, in collaboration with the Lecco Hospital, in 1989 on a group of women living in the Como Lake area (Lombardia), which was one of the areas of Northern Italy most heavily affected by Chernobyl fallout, because of intensive rainfall in the first few days after the accident. The specific diet and caesium content in maternal milk were studied recruiting pregnant women at the ''respiratory autogen training'' course. In this case, Cs-l37, Cs-134 and K-40 concentration in placenta and urine of the mothers under study had also been measured. Aim of this paper is to discuss these data and investigate the relationship between Cs-137 contamination of maternal milk, placenta and urine as a contribution to a better understanding of caesium metabolism in pregnant and nursing women

  1. Bichromatic State-insensitive Trapping of Caesium Atoms

    CERN Document Server

    Metbulut, M M

    2015-01-01

    State-insensitive dipole trapping of multilevel atoms can be achieved by an appropriate choice of the wavelength of the trapping laser, so that the interaction with the different transitions results in equal AC Stark shifts for the ground and excited states of interest. However this approach is severely limited by the availability of coherent sources at the required wavelength and of appropriate power. This work investigates state-insensitive trapping of caesium atoms for which the required wavelength of 935.6 nm is inconvenient in terms of experimental realization. Bichromatic state-insensitive trapping is proposed to overcome the lack of suitable laser sources. We first consider pairs of laser wavelengths in the ratio 1:2 and 1:3, as obtained via second- and third- harmonic generation. We found that the wavelength combinations 931.8-1863.6 nm and 927.5-2782.5 nm are suitable for state-insensitive trapping of caesium atoms. In addition, we examine bichromatic state-insensitive trapping produced by pairs of l...

  2. Bichromatic state-insensitive trapping of caesium atoms

    Science.gov (United States)

    Metbulut, M. M.; Renzoni, F.

    2015-12-01

    State-insensitive dipole trapping of multilevel atoms can be achieved by an appropriate choice of the wavelength of the trapping laser, so that the interaction with the different transitions results in equal AC Stark shifts for the ground and excited states of interest. However this approach is severely limited by the availability of coherent sources at the required wavelength and of appropriate power. This work investigates state-insensitive trapping of caesium atoms for which the required wavelength of 935.6 nm is inconvenient in terms of experimental realization. Bichromatic state-insensitive trapping is proposed to overcome the lack of suitable laser sources. We first consider pairs of laser wavelengths in the ratio 1:2 and 1:3, as obtained via second- and third- harmonic generation. We found that the wavelength combinations 931.8-1863.6 nm and 927.5-2782.5 nm are suitable for state-insensitive trapping of caesium atoms. In addition, we examine bichromatic state-insensitive trapping produced by pairs of laser wavelengths corresponding to currently available high power lasers. These wavelength pairs were found to be in the range of 585-588 nm and 623-629 for one laser and 1064-1080 nm for the other.

  3. Behavioural Changes in Rats Internally Contaminated with Caesium-137

    International Nuclear Information System (INIS)

    Full text: The effect of low doses of 137Cs on the exercise performances, behavioural and learning processes in rats is analysed. The experiments were performed on albino male and female Wistar rats. The animals were divided as follows: two groups, M1 and F1 (males and females) internally contaminated with 490 Bq 137Cs by milk ingestion during 34 days, groups M2 and F2, internally contaminated with 283 Bq by ingestion of milk during 38 days and two control groups. The duration of forced swimming, the active avoidance reaction and the total latency time in the shuttle-box and the score of aggressive behaviour were analysed. The following results were obtained: (1) the duration of forced swimming decreased significantly in the contaminated groups as compared with controls. (2) The active avoidance reaction in the shuttle-box increased in female groups and decrease in male groups. (3) The total latency time of the same reaction was lower in animals internally contaminated with 137Cs in the first day of learning. (4) The score of aggressive behavioural rise significantly, especially in female groups. The results can be explained by neurotoxic action of the caesium on several central neural areas including monoaminergic and endocrine mechanisms and sex dependence of caesium accumulation in the organism. (author)

  4. Migration of 137Cs and 134Cs in different forest soil layers

    International Nuclear Information System (INIS)

    Caesium-134 and 137Cs measurements in about 250 samples from L-, Of-, Oh-, Ah- and B-horizons of a Bavarian forest from 1987 to 1994 are analysed with respect to migration by using a compartment model. The derived ecological half-lives are 2.8 years, 3.8 years, 4.4 years and 7.7 years, respectively. By using these results, caesium behaviour can be predicted for about 25 years. The resulting profile is similar to that found nowadays for weapons fallout caesium, migrating within about 25 years in the same forest. Therefore, the model is suitable for the estimation of future behaviour of radiocaesium in the forest investigated for a period of about 25 years after deposition. (Author)

  5. Industrial treatment of solutions of fission products. Separation of caesium-137

    International Nuclear Information System (INIS)

    Two types of chemical treatment can be considered for the manufacture of solid sources for industrial uses from fission product solutions remaining after plutonium extraction: a) concentration of the solution and preparation of solid sources from the bulk material, without separation, b) separation of one or several fission products from which the sources are made. Examination of the radio-chemical composition of the mixture of fission products that will be available from the Marcoule reactors (G1, G2 and G3) shows that caesium-137 accounts for 30 per cent of the γ energy available immediately after the plutonium separation, 70 per cent two years after and 100 per cent after five years. There is practically no advantage in making sources from bulk fission products, since the separation of caesium-137 is no more complicated and yet it results in a material with more potential uses. The separation of caesium-137 by a method based on the standard phospho-tungstate precipitation method has been considered. Previously, the precipitated caesium phospho-tungstate was dissolved and caesium was recovered from the solution by cation-exchange or by removal of phosphate and tungstate ions by anion-exchange. A study has now been made, of the metathesis of caesium phospho-tungstate to barium phosphate and tungstate by the action of barium hydroxide, the caesium being obtained in solution as the hydroxide. The advantages of this new procedure are: - greater decontamination of caesium-137 without further purification, - possibility of direct transformation to caesium sulphate, - general simplification of the procedure and, consequently, of the equipment. (author)

  6. Caesium sorption-desorption behaviour in bottom sediments

    International Nuclear Information System (INIS)

    The objective of this study is to focus on the sorption and desorption behavior of Cs in the complex heterogeneous system of bottom sediments in order to better understand the cesium behavior during the Baltic Sea water flooding events to the Curronian Lagoon and transport of suspended particles from the Curronian Lagoon to the Baltic Sea. Three sorption and desorption experiments were carried out. A sample of bottom sediments collected in the Curronian Lagoon was used for sorption experiments. Total carbon (TC) and total organic carbon (TOC) were determined using a LECO CS-125 analyser. The stable Cs concentration was determined using ICP-MS, and clay minerals were identified by X-ray diffraction. Filtered sea water of 7.0 salinity labelled with 134Cs was used for the sorption experiment. The total concentration of Cs in solution was 0.04ppb. The solids were separated by centrifugation at 4000 rpm after different contact time between solution and sediments. Details of the experiment are described in publication. The modified Tesser sequential extraction method was used to study association of Cs in sediments. 137Cs and 134Cs activities were measured using an intrinsic germanium detector (resolution 1.9keV/1.33MeV and efficiency - 42%). The precision of 134Cs measurements by gamma spectrometry was 134Cs in sediments after different contact time indicated that more than 70% of 134Cs tracer was sorbed during the first three days. Similar results were obtained during the second experiment. The decrease in the caesium amount in the exchangeable fraction desorbed by NH4+ possibly corresponds to the decrease in the number of frayed edge sites available for Cs sorption. The decrease in the sorption rate accompanied by an increase in association of 134Cs with carbonate fraction can be attributed to the effect of coatings that are usually present in natural heterogeneous sediments. In the sediment sample used for the sorption experiment, a high content of carbonate was

  7. Prepubertal changes in the metabolism of caesium in girls?

    International Nuclear Information System (INIS)

    The results are presented of determinations from 1963 to 1967 of the 137Cs/K ratio in three children (two girls and a younger boy). In the two girls the ratio was at a maximum in late 1963. The decline by a factor of more than four during 1965-1967 was consistent with the contemporaneous reduction in dietary contamination. When adjusted to allow for the decreasing intake, the ratio shows an increase from the age of about 9.5 in each girl. It is suggested that this is a reflection of an increase in the biological half-life of caesium in the girls, associated with prepubertal hormonal changes. 5 refs.; 4 figs.; 2 tabs

  8. Caesium immobilization in hydrated calcium-silicate-aluminate systems

    International Nuclear Information System (INIS)

    A special field of application of cementitious materials in using cements for immobilization of low and medium level radioactive wastes. Clarification of mechanisms of binding is complicated by the multicomponent nature of the solidifying matrix. In the present work, interest is turned to one of the most difficult to confine, long half-life isotopes, the caesium isotope. The cement matrix for solidification of the radioactive waste can be considered, with simplification, as a CaO-SiO2-Al2O3-H2O system. The various compositions of hydrated cementitious assemblages were investigated with respect to their Cs sorption by measuring the Cs distribution ratios (Rd) therein. Trends in sorption properties were detected, and the section of the ternary phase diagram with the best performance was identified

  9. Sorption of caesium in soils from various regions of Libya

    International Nuclear Information System (INIS)

    The sorption characteristics of caesium in some common Libyan soils from various regions of Libya were studied using batch techniques. The influences of clay content, contact time and various concentrations of Cs+, K+, and NH4+ in the solution on the sorption ratio for Cs+ were determined by using tracer 134Cs. All experiments were carried out in the presence of a supporting electrolyte (0.01 N CaCl2). An apparent steady state was reached in 4 - 7 days. Important parameters influencing the sorption were clay content, pH, and the concentrations of other cations, in particular K+ and NH4+ which compete with Cs+ for the sorption sites. (orig.)

  10. Highly efficient H- ion source for cyclotrons without caesium

    International Nuclear Information System (INIS)

    Full text: An internal high current H- ion source for cyclotrons and other injectors was developed which makes use of some very effective methods of H- ion production. The source is distinguished by high gas efficiency. A surface-plasma method for H- ion production without using caesium vapor was realized. A strong current arc discharge was applied for dissociation and dissociative ionization of H2 molecules. An H+-H- recharge method using a residual gas layer adjusted by thickness and pressure was realized in this source. In a double-chamber ion source with high-current discharge in the single chamber and low-current low-volt discharge in the different chamber is used the supplementary electrode which a composite-plate cover with low electronic work function (∼1,5 eV). Anticipate of ion current of H- is 1-2 mA. (author)

  11. Observation of EIA in closed and open caesium atomic system

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

    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 → 6P3/2F'=3 open transitions was also obtained. As the repumping laser couples with the transition of 6S1/2 F=3 → 6P3/2F'=4, the EIA signal is increased due to the hyperfine optical pumping.

  12. Crustaceous lichens sensitive monitor of caesium-137 radiation level in terrestrial environment

    Institute of Scientific and Technical Information of China (English)

    Du Chunguang; Zhao Ye; Zhang Jing; Xu Cuihua

    2005-01-01

    The activity of caesium-137 (Bq/kg) in the crustaceous lichens and other samples was determined to prove the feasibility that crustaceous lichens work as a sensitive biology monitor to record the caesium-137 (Bq/kg) radiation levels of terrestrial environment. The measurements were performed with GEM series HPGe (high-purity Germanium) coaxial detector system (ADCAM -100) made by EC & GORTEC Company in USA. It was found that the activity of caesium-137 (Bq/kg) in the crustaceous lichens was one order of magnitude higher than that found in surface soil,and was over three orders of magnitude higher than those found in the familiar biological samples. These results proved that crustaceous lichens may be one of the most sensitive biological monitors about the remote transmission and environmental radiation levels of caesium-137.

  13. Modelling of radionuclide migration in forest ecosystems. A literature review

    Energy Technology Data Exchange (ETDEWEB)

    Avila, R.; Moberg, L.; Hubbard, L.

    1998-03-01

    The Chernobyl accident has clearly shown the long-term effects of a radioactive contamination of forest ecosystems. This report is based on a literature review of models which describe the migration of radionuclides, radioactive caesium in particular, in forest ecosystems. The report describes the particularities of the forest ecosystem, the time dynamics of the contamination, the transfer processes and factors influencing caesium migration. This provides a basis for a discussion of different approaches for modelling caesium migration in the forest. It is concluded that the studied dynamic models include the most relevant transfer processes both for the acute and the long-term phase after a radioactive deposition. However, most models are site specific and do not consider some of the factors responsible for the differences in radionuclide behaviour and distribution in different types of forests. Although model improvements are constrained by the availability of experimental data and by the lack of knowledge of the migration mechanisms some possible improvements are discussed. This report is part of the LANDSCAPE project. -An integrated approach to radionuclide flow in the semi-natural ecosystems underlying exposure pathways to man. 42 refs, 3 tabs, 9 figs.

  14. Modelling of radionuclide migration in forest ecosystems. A literature review

    International Nuclear Information System (INIS)

    The Chernobyl accident has clearly shown the long-term effects of a radioactive contamination of forest ecosystems. This report is based on a literature review of models which describe the migration of radionuclides, radioactive caesium in particular, in forest ecosystems. The report describes the particularities of the forest ecosystem, the time dynamics of the contamination, the transfer processes and factors influencing caesium migration. This provides a basis for a discussion of different approaches for modelling caesium migration in the forest. It is concluded that the studied dynamic models include the most relevant transfer processes both for the acute and the long-term phase after a radioactive deposition. However, most models are site specific and do not consider some of the factors responsible for the differences in radionuclide behaviour and distribution in different types of forests. Although model improvements are constrained by the availability of experimental data and by the lack of knowledge of the migration mechanisms some possible improvements are discussed. This report is part of the LANDSCAPE project. -An integrated approach to radionuclide flow in the semi-natural ecosystems underlying exposure pathways to man

  15. Molecular and collisional processes during three photon ionisation transitions in caesium and rubidium vapours

    International Nuclear Information System (INIS)

    Interesting molecular and collisional processes are evident during three photon ionisation transitions in caesium and rubidium vapours. In particular, for caesium vapour broad hybrid resonances (molecular plus atomic transitions) have been identified. In rubidium vapour three photon ionisation s-nd, s-ns transitions as well as forbidden s-np have been observed with the s-s transitions being more prominent than theory predicts. These observations have been explained in terms of collisional ionisation. (author)

  16. Density functional theory metadynamics of silver, caesium and palladium diffusion at β-SiC grain boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Rabone, Jeremy, E-mail: jeremy.rabone@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, D-76125 Karlsruhe (Germany); López-Honorato, Eddie [Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV), Unidad Saltillo, Industria Metalúrgica 1062, Parque Industrial, Ramos Arizpe 25900, Coahuila (Mexico)

    2015-03-15

    Highlights: • DFT metadynamics of diffusion of Pd, Ag and Cs on grain boundaries in β-SiC. • The calculated diffusion rates for Pd and Ag tally with experimental release rates. • A mechanism of release other than grain boundary diffusion seems likely for Cs. - Abstract: The use of silicon carbide in coated nuclear fuel particles relies on this materials impermeability towards fission products under normal operating conditions. Determining the underlying factors that control the rate at which radionuclides such as Silver-110m and Caesium-137 can cross the silicon carbide barrier layers, and at which fission products such as palladium could compromise or otherwise alter the nature of this layer, are of paramount importance for the safety of this fuel. To this end, DFT-based metadynamics simulations are applied to the atomic diffusion of silver, caesium and palladium along a Σ5 grain boundary and to palladium along a carbon-rich Σ3 grain boundary in cubic silicon carbide at 1500 K. For silver, the calculated diffusion coefficients lie in a similar range (7.04 × 10{sup −19}–3.69 × 10{sup −17} m{sup 2} s{sup −1}) as determined experimentally. For caesium, the calculated diffusion rates are very much slower (3.91 × 10{sup −23}–2.15 × 10{sup −21} m{sup 2} s{sup −1}) than found experimentally, suggesting a different mechanism to the simulation. Conversely, the calculated atomic diffusion of palladium is very much faster (7.96 × 10{sup −11}–7.26 × 10{sup −9} m{sup 2} s{sup −1}) than the observed penetration rate of palladium nodules. This points to the slow dissolution and rapid regrowth of palladium nodules as a possible ingress mechanism in addition to the previously suggested migration of entire nodules along grain boundaries. The diffusion rate of palladium along the Σ3 grain boundary was calculated to be slightly slower (2.38 × 10{sup −11}–8.24 × 10{sup −10} m{sup 2} s{sup −1}) than along the Σ5 grain boundary. Rather

  17. Isothermal Gaseous Detonation Model

    Science.gov (United States)

    Prokhorov, E. S.

    2015-05-01

    We propose an isothermal gaseous detonation model taking into account the initial pressure of the explosive mixture that permits describing in a simplified form both the self-sustaining and the supercompressed and undercompressed detonation regimes. The exactness of this model has been estimated on the basis of a comparative analysis with the results of equilibrium calculations of the gas-dynamic parameters at the front of detonation waves.

  18. Isothermal Martensite Formation

    DEFF Research Database (Denmark)

    Villa, Matteo

    Isothermal (i.e. time dependent) martensite formation in steel was first observed in the 40ies of the XXth century and is still treated as an anomaly in the description of martensite formation which is considered as a-thermal (i.e. independent of time). Recently, the clarification of the mechanism...... leading to isothermal kinetics acquired new practical relevance because of the identification of isothermal martensite formation as the most likely process responsible for enhanced performances of sub-zero Celsius treated high carbon steel products. In the present work, different iron based alloys are...... chosen to investigate time dependent martensite formation. Among them, a Fe-11wt%Ni-0.6wt%C model alloy and Fe-1.6wt%Cr-1wt%C (AISI 52100), Fe-17wt%Cr-7wt%Ni (AISI 631) and Fe-16wt%Cr-5wt%Ni (AISI 630) commercial steels. The investigation was performed with in situ magnetometry, dilatometry, synchrotron...

  19. The behaviour of fission product caesium in LMFBR primary circuits: experiments in a small stainless steel loop containing circulating sodium

    International Nuclear Information System (INIS)

    The available information which can be used to determine the likely behaviour of fission product caesium, released from defective fuel pins, in the primary circuit of a sodium-cooled fast reactor has been reviewed and assessed. For a relatively small number of fuel pin failures over a reactor lifetime 137Cs is potentially a predominant contributor to dose rates on out-of-core steel components if the adsorption of caesium on these components is sufficiently high. Shortcomings are identified in the existing data on caesium adsorption from liquid sodium onto austenitic steel surfaces. This has enabled the definition of those areas of work which are necessary before the behaviour of fission product caesium in the primary circuit, and the possible requirement of any alleviatory measures, can be predicted with precision and confidence. Experiments are described from which the mechanism of adsorption of caesium onto steel surfaces was elucidated, thereby enabling the prediction of the likely sorption behaviour of fission product caesium on components in the primary circuits of LMFBRs. The potential use of cold-trapping as a means of removing caesium from sodium was also investigated and found to be of no significant value; alternative methods for caesium removal are discussed. The development of methods for decontamination of steelwork which has become contaminated by caesium sorption onto chromium (III) oxides is described, although it is not clear that the levels of contamination which would arise by this mechanism under normal LMFBR operating conditions would necessitate such treatment. (author)

  20. DECOMMISSIONING OF A CAESIUM-137 SEALED SOURCE PRODUCTION FACILITY

    Energy Technology Data Exchange (ETDEWEB)

    Murray, A.; Abbott, H.

    2003-02-27

    Amersham owns a former Caesium-137 sealed source production facility. They commissioned RWE NUKEM to carry out an Option Study to determine a strategy for the management of this facility and then the subsequent decommissioning of it. The decommissioning was carried out in two sequential phases. Firstly robotic decommissioning followed by a phase of manual decommissioning. This paper describes the remote equipment designed built and operated, the robotic and manual decommissioning operations performed, the Safety Management arrangements and summarizes the lessons learned. Using the equipment described the facility was dismantled and decontaminated robotically. Some 2300kg of Intermediate Level Waste containing in the order of 4000Ci were removed robotically from the facility. Ambient dose rates were reduced from 100's of R per hour {gamma} to 100's of mR per hour {gamma}. The Telerobotic System was then removed to allow man access to complete the decommissioning. Manual decommissioning reduced ambient dose rates further to less than 1mR per hour {gamma} and loose contamination levels to less than 0.25Bq/cm2. This allowed access to the facility without respiratory protection.

  1. Determination of erosion and accretion rates using caesium-137

    International Nuclear Information System (INIS)

    Within drainage basins, soil erosion status may be indicated by levels of absorbed 137Cs within the soil. Further refinements of the relationship between soil loss and 137Cs loss for various soil types, geographic locations for soils experiencing severe erosion will enable more accurate predictions of net soil loss rates to be made. For a long time quantification of sediment sources within catchments has been a difficulty for hydrogeomorphologists interpreting sediment outputs, and the 137Cs technique holds much promise for its resolution. Storage, another major component of the sediment budget, may also be quantified by 137Cs, provided careful sampling and interpretation are practised. Caesium-137 as a dating-tool is less useful at sites with low rates of sediment accumulation, ostensibly those unaffected by human activity in the catchment. The tracer 137Cs has become a well-established tool in sediment research in several countries. The provision of adequate detector facilities will ensure the further development of the technique in Australia, thus helping hydrogeomorphologists achieve the goal of predicting sediment delivery ratios and drainage basin sediment budgets with some certainty

  2. Influence of chemical composition of precipitation on migration of radioactive caesium in natural soils

    International Nuclear Information System (INIS)

    The aim of the present work was to study the impact of the chemical composition of precipitation on radiocaesium mobility in natural soil. This was done through column studies. Three types of precipitation regimes were studied, representing a natural range found in Norway: Acidic precipitation (southernmost part of the country); precipitation rich in marine cations (highly oceanic coastal areas); and low concentrations of sea salts (slightly continental inland areas). After 50 weeks and a total precipitation supply of ∼10 000 L m−2 per column, results indicate that acidic precipitation increased the mobility of 134Cs added during the experiment. However, depth distribution of already present Chernobyl fallout 137Cs was not significantly affected by the chemical composition of precipitation. - Highlights: • Mobility of freshly added Cs-134 was higher in soil receiving acidic precipitation. • Depth penetration of Cs-134 was higher in soil profiles with a thicker humus layer. • Depth distribution of Chernobyl Cs-137 was not affected by precipitation type

  3. The effect of caesium and xenon addition on negative hydrogen ion production

    International Nuclear Information System (INIS)

    The presence of caesium in hydrogen discharges is known to increase the extracted negative hydrogen ion current by up to sixteen fold. The mechanism for this phenomenon is not understood. Here Langmuir probe and photodetachment techniques have been used to measure the effects on plasma parameters, including the negative ion density, of adding caesium and xenon to a multicusp ion source. The addition of xenon, also a heavy element but unreactive, allows possible negative ion confinement effects to be explored. No significant change in the negative ion density was observed when up to 20% xenon was introduced, although other plasma parameter changes were observed. Caesium addition increased the negative ion concentration. This increase was found to depend on the wall temperature. copyright 1996 American Institute of Physics

  4. Recent studies on the interception and the retention of caesium by grass, barley and peas

    International Nuclear Information System (INIS)

    Experiments with artificial depositions of radio caesium during the growth period have been carried out. The studies are complementary to experiences after the Chernobyl fallout and aimed at a description of the relative transfer to the harvest products of grass, barley and peas after initial interception during growth. It was found that the apparent residence half-time of caesium in grass on old established leys producing winter feed was about one month and that the reduction in nuclide content up to the harvest time for this reason mainly depended on dilution by growth. Also the grain crops were found to be sensitive to depositions during almost the whole season. It should be due to translocation of caesium within the plant. The data obtained can make the basis for prediction of the consequences of fallouts. (au)

  5. Caesium dynamics in the peats and associated vegetation of northern Greece and northern Scotland

    International Nuclear Information System (INIS)

    Sequential analyses have shown that Chernobyl-derived caesium has been largely retained in Greek basin peats (highly cultivated, base-rich, sedge peats) and retained/cycled in Scottish upland peats (uncultivated, base-poor, blanket peats). To investigate the mechanisms of retention and cycling in the Scottish peat/vegetation system, a laboratory experiment was carried out involving 'microcosms' intact peat cores. Festuca ovina was grown from seed in the cores prior to nebuliser-application of simulated rain containing caesium-134. The major factors investigated were competitive ion exchange from ammonium (designed to simulate animal waste inputs), freeze-thaw activity, and cropping (designed to simulate upland grazing). The effects of these factors are discussed in relation to the physio-cochemical and biological properties of the peat and vegetation and to our observations of the movement of caesium in the field. (author)

  6. A simple method with imaging plates for examination of soil contaminated with radioactive caesium

    International Nuclear Information System (INIS)

    A simple and convenient system with imaging plates (IPs) was well constructed for the radioactivity examination of soil contaminated with radioactive caesium. A set of two IP strips was vacuum-sealed with thin polyethylene film to prevent the IP strips from direct contacting soil and from being moisturized. In the examination of radioactive soil, a stainless steel pipe including this IP strip monitor was put into the ground and then it was kept in a lead container after being pulled out of the ground for the reduction of the surrounding gamma-ray background. In addition, a sensitive reader was well made for the measurement of the photostimulated luminescence through the scanning of a laser beam on the IP strip. It was confirmed from experiments on actual radioactive-caesium-contaminated soil that the IP strip monitor with the reader effectively detected beta-rays from radioactive caesium and could be satisfactorily used for the examination of radioactive soil. (author)

  7. Uptake and retention of radio-caesium in earthworms cultured in soil contaminated by the Fukushima nuclear power plant accident

    International Nuclear Information System (INIS)

    To understand the effects of radionuclides on non-human biota and the environment, it is essential to study the intake and metabolism of radio-isotopes in earthworms which are among the most important soil organisms, and Eisenia fetida, which were used in this study, are known to be sufficiently sensitive to chemicals and representative of common earthworms. In this study, we assessed the concentration ratios, uptake and retention, absorbed dose rate, and distribution of radio-caesium in earthworms. The concentration ratios of 137Cs (i.e., the concentrations of radio-caesium in earthworms relative to those in dry soil) were higher early in the culturing period and decreased gradually over the experimental period. 137Cs taken up by E. fetida was cleared rapidly after the worms were cultured in radio-caesium-free soil, suggesting that the metabolism of radio-caesium in earthworms is very rapid. Autoradiography demonstrated that the concentration of radio-caesium within the digestive tract was as high as that in the soil, while radio-caesium in the body tissue was lower than radio-caesium in the soil and was almost uniformly distributed among earthworm tissues. The highest absorbed dose rate of total exposure to radio-caesium (137Cs + 134Cs) was calculated to be 1.9 × 103 (μGy/day) in the earthworms. - Highlights: • We assessed the concentration ratios of 137Cs in earthworms/dry soil. • The distribution of radio-caesium was relatively uniform throughout the earthworm body without any distinguishable accumulation in specific organs or tissues. • We estimated the absorbed dose rate of radio-caesium for earthworms

  8. The Body Burden of Caesium-137 in People of Southern Finland 1961-1963

    International Nuclear Information System (INIS)

    In connection with the investigations of the caesium-137, body burden of Finnish Lapps several measurements of smaller groups of people living in Southern Finland were carried out. In November 1961 eleven Helsinki inhabitants, five men and six women, 15 to 54 yr. old, were counted for caesium-137 and potassium in Stockholm. None of these persons were laboratory workers, two were schoolboys. They were apparently healthy. Their diet was studied by the interview method. Ten of these people were counted again in the mobile whole-body counter of the Radiochemical Department of the University of Helsinki one year later. The average body burden of caesium-137 in men (5, average age 29) had increased from 8.4 nc in November 1961 to 18.4 nc in November 1962, in women (5, average age 34) from 2.9 nc to 8.7 nc. Potassium contents were the same within 2% (men 140 g, women, 100 g) For more detailed studies larger control groups were selected at the beginning of 1963 and counted four times, in February, May, August and October. For the group of men 25 privates of an infantry battalion (age 19, average weight 65 kg), for women 24 girl students of a household school (age 22, average weight 60 kg), were selected. In both cases the diet could be checked in detail and could be considered to be an average Finnish diet. In addition, the individual food consumption of each subject was studied by interview with the aid of weighed samples. Caesium-137 contents of both diets were determined for the time periods between the measurements. In both groups the caesium-137 content remained about constant (men, 17,5 nc; women, 11 nc) until the end of June, when the caesium-137 content of milk and meat was approximately doubled within about one week. At the end of August the body burden of caesium-137 had increased in, both groups to about 40% above the spring level in the middle of October the men's values had increased by 22%, the women's values by 14% of the August level. The determination of

  9. Radiometric detection of non-radioactive caesium flux using displaced naturally abundant potassium

    International Nuclear Information System (INIS)

    We report on a method that allows for the radiometric detection of non-radioactive caesium by the measurement of potassium ions displaced from an ion exchange barrier. Electrokinetic transport of K+ and Cs+ through concrete samples was measured using a bespoke scintillation detector to monitor electrolyte concentrations. Results show experimental ionic flux and diffusion parameters of non-active caesium (∼1 x 10-5 mol m-3) were consistent with those recorded for potassium and also with values reported in relevant literature. This work demonstrates a novel concept that can be applied to proof-of-concept studies that help develop the next generation of nuclear decommissioning technologies. (author)

  10. Investigations on caesium 134 and 137 contamination of game hunted for food in Hessia

    International Nuclear Information System (INIS)

    The amount of caesium 134 and 137 in Hessian game hunted for food (556 animals) after the reactor accident at Chernobyl was investigated. Comparisons have been made before and after the accident. Although there was only a very low level of contamination, the contamination rate of different species varied; on average, the Red Deer showed the highest activity (130 Bq/kg). The level of caesium contamination was mostly influenced by the permanent habitat of the animals. The main influence was due to regional, geographical and meteorological conditions. The influence of age or sex could not be determined. The contamination rate was shown to decrease with time

  11. Kinetics of caesium and potassium absorption by roots of three grass pastures and competitive effects of potassium on caesium uptake in Cynodon sp

    International Nuclear Information System (INIS)

    Caesium uptake by plant roots has been normally associated with the uptake of potassium as the potassium transport systems present in plants have also the capacity to transport caesium. Three grass species (Eragrostis curvula, Cynodon sp and Distichlis spicata) growing in seminatural grassland of central Argentina were selected to study their capability to incorporate Cs+ (and K+) using electrophysiological techniques. Although the 137Cs soil inventory ranged between 328-730 Bq m-2 in this region, no 137Cs activity was detected in these plants. However, all the species, submitted previously to K+ starvation, showed the uptake of both Cs+ and K+ when micromolar concentrations of these cations were present in the medium. The uptake showed saturation kinetics for both cations that could be fitted to the Michelis-Menten model. KM values were smaller for K+ than for Cs+, indicating a higher affinity for the first cation. The presence of increasing K+ concentrations in the assay medium inhibited Cs+ uptake in Cynodon sp., as expected if both cations are transported by the same transport systems. This effect is due to the competition of both ions for the union sites of the high affinity potassium transporters. In field situation, where soil concentration of Cs+ is smaller than K+ concentration, is then expectable that caesium activity in plants is not detectable. Nevertheless, the studied plants would have the capacity to incorporate caesium if its availability in soil solution increases. In addition, studies of Cs/K interaction can help us to understand the variability in transfer factors

  12. Kinetics of caesium and potassium absorption by roots of three grass pastures and competitive effects of potassium on caesium uptake in Cynodon sp.

    Science.gov (United States)

    Ayub, J. Juri; Valverde, L. Rubio; Garcia-Sanchez, M. J.; Fernandez, J. A.; Velasco, R. H.

    2008-08-01

    Caesium uptake by plant roots has been normally associated with the uptake of potassium as the potassium transport systems present in plants have also the capacity to transport caesium. Three grass species (Eragrostis curvula, Cynodon sp and Distichlis spicata) growing in seminatural grassland of central Argentina were selected to study their capability to incorporate Cs+ (and K+) using electrophysiological techniques. Although the 137Cs soil inventory ranged between 328-730 Bq m-2 in this region, no 137Cs activity was detected in these plants. However, all the species, submitted previously to K+ starvation, showed the uptake of both Cs+ and K+ when micromolar concentrations of these cations were present in the medium. The uptake showed saturation kinetics for both cations that could be fitted to the Michelis-Menten model. KM values were smaller for K+ than for Cs+, indicating a higher affinity for the first cation. The presence of increasing K+ concentrations in the assay medium inhibited Cs+ uptake in Cynodon sp., as expected if both cations are transported by the same transport systems. This effect is due to the competition of both ions for the union sites of the high affinity potassium transporters. In field situation, where soil concentration of Cs+ is smaller than K+ concentration, is then expectable that caesium activity in plants is not detectable. Nevertheless, the studied plants would have the capacity to incorporate caesium if its availability in soil solution increases. In addition, studies of Cs/K interaction can help us to understand the variability in transfer factors.

  13. Adsorption of nuclides on hydrous oxides: Sorption isotherms on natural materials

    International Nuclear Information System (INIS)

    Hydrous oxides and minerals which have adsorbing groups that behave like hydrous oxides are ubiquitous components of geological formations and may dominate the adsorptive properties of the formations at conditions of natural groundwaters. An understanding of the adsorptive behavior of hydrous oxides is therefore necessary for reliable prediction of migration of nuclides through the formations. Various isotherms are derived from equilibrium ion-exchange theory for the sorption of non-hydrolyzed ions on hydrous oxides. These isotherms are compared with experimental isotherms for sorption of Cs/sup +/, Sr/sup 2+/, Eu/sup 3+/, and TcO/sub 4//sup -/ on several hydrous oxides. General features of these isotherms are predictable from ion-exchange equilibrium theory as applied to hydrous oxides. By combining isotherms for hydrous oxides with those for layer-type clay minerals, many unusual features of isotherms found on geological materials can be explained

  14. Caesium activity in nursing mothers and in the mother's milk one year after Chernobyl accident

    International Nuclear Information System (INIS)

    Linear correlation between Cs-137 concentration in mother's milk and the mother's Cs-137 whole body activity was obtained. A simple metabolic model is proposed to interpret measured data. Caesium activity in mother's milk was five times lower than in dairy products. (orig./HP)

  15. The selectivity of zirconium phosphate for caesium in electrochemical ion exchange

    International Nuclear Information System (INIS)

    The properties of amorphous zirconium phosphate are investigated as an inorganic ion exchanger for use in liquid waste treatment by electrochemical ion exchange. Experiments to determine and increase the selectivity for caesium exchange over sodium are discussed, including various pulsed waveforms and studies with rotating membranes. Automation of a sampling system with pH and atomic absorption measurements is described. (author)

  16. In vivo experiments on the accumulation of caesium-134 in heart and skeletal muscle of pigs

    International Nuclear Information System (INIS)

    The accumulation of 134Cs in muscle tissue of pigs after intravenous application of the isotope was studied. Calculated on the basis of plasma concentration the accumulation of the caesium isotope in muscle tissue was quantitatively affected by the following factors: mode and duration of application (single dose or continuous application), condition of the muscle (healthy or damaged muscle), proportion of red fibres in the muscle, and time elapsed between end of infusion and assay. The excretion of 134Cs from plasma of pigs by the kidney and intestine was faster than the removal of the caesium isotope from skeletal muscles. Two weeks after a l6-day period of continuous infusion of 134Cs, the radioisotope concentrations in skeletal muscles were 150 to 400 times those found in plasma. Compared with potassium ions in muscles, accumulation of the heavier and slightly larger caesium ions was 1.7 to 2.5 times higher. Caesium accumulation in muscles with a relatively high proportion of red fibres was higher than in white muscles. When the muscles were damaged by feeding a selenium- and vitamin-E-deficient diet for six weeks, accumulation of 134Cs was greatly reduced. (author)

  17. Theoretical calculations of primary particle condensation for cadmium and caesium iodide vapours

    International Nuclear Information System (INIS)

    This report considers a model of aerosol nucleation from the vapour phase which has been developed by Buckle. The applicability of the model has been tested by considering the condensation of caesium iodide and cadmium vapours under a wide variety of pre-mixed flow conditions of interest to PWR severe accident studies. (U.K.)

  18. Rhenium volatilisation as caesium perrhenate from simulated vitrified high level waste from a melter crucible

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, T.A.; Short, R.J.; Gribble, N.R.; Roe, J.I. [National Nuclear Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom); Steele, C.J. [Sellafield Ltd, Sellafield, Seascale, Cumbria, CA20 1PG (United Kingdom)

    2013-07-01

    The Waste Vitrification Plant (WVP) converts Highly Active Liquor (HAL) from spent nuclear fuel reprocessing into a stable vitrified product. Recently WVP have been experiencing accumulation of solids in their primary off gas (POG) system leading to potential blockages. Chemical analysis of the blockage material via Laser Induced Breakdown Spectroscopy (LIBS) has shown it to exclusively consist of caesium, technetium and oxygen. The solids are understood to be caesium pertechnetate (CsTcO{sub 4}), resulting from the volatilisation of caesium and technetium from the high level waste glass melt. Using rhenium as a chemical surrogate for technetium, a series of full scale experiments have been performed in order to understand the mechanism of rhenium volatilisation as caesium perrhenate (CsReO{sub 4}), and therefore technetium volatilisation as CsTcO{sub 4}. These experiments explored the factors governing volatilisation rates from the melt, potential methods of minimising the amount of volatilisation, and various strategies for mitigating the deleterious effects of the volatile material on the POG. This paper presents the results from those experiments, and discusses potential methods to minimise blockages that can be implemented on WVP, so that the frequency of the CsTcO{sub 4} blockages can be reduced or even eradicated altogether. (authors)

  19. Caesium inhibits the colonization of Medicago truncatula by arbuscular mycorrhizal fungi

    International Nuclear Information System (INIS)

    Contamination of soils with radioisotopes of caesium (Cs) is of concern because of their emissions of harmful β and γ radiation. Radiocaesium enters the food chain through vegetation and the intake of Cs can affect the health of organisms. Arbuscular mycorrhizal (AM) fungi form mutualistic symbioses with plants through colonization of the roots and previous studies on the influence of AM on Cs concentrations in plants have given inconsistent results. These studies did not investigate the influence of Cs on AM fungi and it is therefore not known if Cs has a direct effect on AM colonization. Here, we investigated whether Cs influences AM colonization and if this effect impacts on the influence of Rhizophagus intraradices on Cs accumulation by Medicago truncatula. M. truncatula was grown with or without R. intraradices in pots containing different concentrations of Cs. Here, we present the first evidence that colonization of plants by AM fungi can be negatively affected by increasing Cs concentrations in the soil. Mycorrhizal colonization had little effect on root or shoot Cs concentrations. In conclusion, the colonization by AM fungi is impaired by high Cs concentrations and this direct effect of soil Cs on AM colonization might explain the inconsistent results reported in literature that have shown increased, decreased or unaffected Cs concentrations in AM plants. - Highlights: • Colonization of plants by arbuscular mycorrhizal fungi is negatively affected by increasing soil caesium concentrations. • Shoot caesium concentrations are not influenced by AM fungi at soil caesium concentrations above about 3 μg Cs kg−1. • The direct effect of caesium on AM fungi might impact on the influence of AM fungi on Cs accumulation in plants. • This might explain the inconsistent results reported in literature on Cs accumulation in AM plants

  20. The use of bentonite and zeolite as caesium-binders in feed to reindeer - experiences from Sweden

    Directory of Open Access Journals (Sweden)

    Birgitta Åhman

    1990-09-01

    Full Text Available Feeding is used in Sweden to lower radiocaesium levels in reindeer before slaughter. In feeds used for this purpose, bentonite is added as a caesium-binder to prevent absorption of radiocaesium, since the animals usually have som access to contaminated pasture in their corrals. Bentonite is efficient as a caesium-binder but increases water consumption and excretion of urine. Zeolite has been used as a caesium-binder to reindeer in a few experiments. The effect, however, has been inferior to that of bentonite. It seems that zeolite, mixed in feeds, loose some of its effect as the feed is stored. The need of a caesium-binder is demonstrated by results from practical feeding of reindeer where radiocaesium levels have not decreased as expected when feed without bentonite has been used.

  1. Deposition of caesium and strontium substances on growing crops: Effects and countermeasures

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, S. (Swedish Univ. of Agricultural Sciences, Dept. of Soil and Environment (Sweden))

    2010-03-15

    Full text: To investigate how the two radionuclides caesium (134Cs) and strontium (85Sr) are taken up and transported to the harvested parts (the seeds) by fallout in a growing crop. Further on how this is related to the size and time of the fallout. From the information collected recommendation of suitable countermeasures at different scenarios to prevent further spreading to food stuff can be suggested. In the project a number of field trials where artificial deposited by the two radionuclides 134Cs and 85Sr in a contaminated rainfall, on the two agricultural crops Brassica napus L. (spring rape) and Triticum aestivum L. (spring wheat). The trial contained different treatments where the radionuclides where deposited by a rainfall simulator at different growing stages of the crops. The field trial continues for two more years and the reason for that is due to the variation of the climate for the different years. The radionuclides were applied in the form of a wet deposition and the rainfall was about 1 mm m-1 with a concentration of 20 kBq m-1 for each radionuclide. Samples were taken from the plots at the day(s) after the treatment of contaminated rainfall, both from the latest treated plots and from the earlier treated plots. The hypotheses are: 1. That the size of the deposition and the time in relation to the development stages of the crop will steer how much caesium and strontium that are coughed, detained and transferred to the harvested parts. 2. That the levels of caesium and strontium in the harvested parts of the crops are related to the insensitivity of the rainfall after a deposition and also how long time the first intensive rain will occur. 3. That the size of caesium and strontium in harvested plant parts are related to the size of uptake throw the leaves. 4. If the deposition of caesium and strontium will be the same, the levels of caesium will be much higher than strontium in the harvested parts. (author)

  2. Caesium-137 as an indicator of geomorphic processes in a drainage basin system

    International Nuclear Information System (INIS)

    Caesium-137 from fallout from nuclear weapons tests is adsorbed on fine sediments and becomes an effective tracer. It is hypothesised that within a drainage basin, sites undergoing little or no erosion accumulate Cs-137 in their upper layers; cultivated soils will have Cs-137 uniformly distributed within the cultivated layer; eroded soils, cultivated or not, will have relatively less Cs-137, depending on the severity of erosion. Accumulated sediments will have characteristic Cs-137 profiles reflecting temporal fallout variations and sedimentation history. This hypothetical model is largely confirmed by results from Maluna Creek basin, where erosion and accumulation of sediments has taken place. Soils under viticulture have about one third the Cs-137 content of soils with grass cover, indicating more severe erosion under cultivation. Caesium-137 profiles in alluvial fan and flood plain deposits correlate with sediment layers and known cultivation history

  3. New ion selective materials. Application to the selective extraction of caesium

    International Nuclear Information System (INIS)

    This research thesis addresses the synthesis and assessment of ion selective materials. The first part reports the development of a general method of assessment of ion selective materials. In the second part, the author describes different methods used to insolubilize macro-cycles on hydrophilic polymers. The obtained polyurethanes are synthesised. These hydrophilic polymers display interesting complexing properties and selectivities with respect to cations of alkali metals. Then the author addresses the improvement of selectivity with respect to caesium of ion exchange resorcinol-formaldehyde resins. Different factors affecting selectivity are identified, and the concept of molecular print is used to study the improvement of selectivity. The effect of macro-cyclic structures on phenolic resins with respect to caesium is highlighted

  4. Experimental investigations of caesium and iodine release from irradiated UO2

    International Nuclear Information System (INIS)

    The modelling of the behaviour of fuel rods whose temperature is rising requires a knowledge of fission product release under such conditions. For this purpose an experimental apparatus has been developed and built for the determination of vapour pressures by the Knudsen method. The results obtained on UO2 samples of light-water reactor fuel with a burnup of 32 MWd tU-1 shows that a noticeable release of iodine and caesium occurs only at fuel temperature above 1400-15000C. Thus the influence of iodine on the mechanical behaviour of fuel rods under loss-of-coolant-accident conditions can be neglected. The onset temperature for iodine release matches excellently the pellet-clad-interaction (PCI) threshold identified in ramping experiments. The relative release is nearly equal for iodine and caesium, and increases rapidly with temperature and burnup. (author)

  5. Psychosocial aspects of the victims of the accident with caesium-137 in Goiania (1987-1994)

    International Nuclear Information System (INIS)

    In September of 1987 two men took possession of and violated a source containing Caesium-137, which caused the Radiological Accident of Goiania. Besides the direct victims, a significant part of the community of Goiania was directly involved with this accident. The psychosocial impact in the social groups involved in this radiological accident - the population as a whole, immediate neighbours of contaminated sites, professionals and the victims themselves - gave rise to specific behaviour and attitudes which will be discussed in this paper. (author)

  6. Caesium-137 in a boreal forest ecosystem. Aspects on the long-term behaviour

    International Nuclear Information System (INIS)

    Cycling of radioactive caesium, particularly the isotope Cs-137, is studied in boreal forest biotopes mainly located at the Vindeln experimental forest, 60 km NW of Umeaa, Sweden, (64 degrees 16'N, 19 degrees 48'E). The distribution of radioactive caesium in this forest ecosystem, prior to and in different periods after the Chernobyl accident, reflects the existence of fast changes particularly at an early stage after the deposition, superimposed on slow redistribution over long time periods. The definite causes to this complex dynamic behaviour are not yet unambiguously established. In this work we use the specific results from local field studies as a basis to describe the general pattern and time dependence of Cs-137 redistribution in a boreal forest. We raise the hypothesis that: 'Cs-137 present in a boreal forest tends towards a homogenous distribution among the living cells of that system'. This hypothesis is based on physiological characteristics concerning transport over cell membranes and intracellular distribution in comparison to potassium, and the apparently conservative conditions prevailing for caesium in boreal ecosystems - e.g. the facts that very little of the radioactive caesium deposited over the forest area is lost from the system by run off, more than 90% of the total deposition of Cs-137 resides in the upper organic horizon in podzol areas, and that the availability in the ecosystem, as can be seen from the Cs-137 concentration in moose meat, is not significantly different in 1985 (i.e. prior to the Chernobyl accident) in comparison to the period 1986-1990. The aim of this work is to elucidate how predictions, based on our hypothesis about redistribution processes in the boreal forest, corroborates with the main features in the time-dependent change of Cs-137 activity, according to measurements on perennial vegetation from the local sites. In particular the implicit dependence of the dynamics of the redistribution processes on primary

  7. Investigations on frequency distribution of whole-body retention parameters of caesium in humans

    International Nuclear Information System (INIS)

    The fission product caesium radionuclides, 137Cs and 134Cs, play an important role in internal dose received by members of the population as the consequence of reactor accidents or nuclear weapon tests. Better knowledge on the biokinetic parameters of these radionuclides leads to more realistic dose estimate. Since these parameters, apart from their age and sex dependence have also individual variability, it is worth to investigate quantitatively and characterize statistically these variations. (author)

  8. BINDING ISOTHERMS SURFACTANT-PROTEINS

    OpenAIRE

    Elena Irina Moater; Cristiana Radulescu; Ionica Ionita

    2011-01-01

    The interactions between surfactants and proteins shows some similarities with interactions between surfactants and polymers, but the hydrophobic amphoteric nature of proteins and their secondary and tertiary structure components make them different from conventional polymer systems. Many studies from the past about surfactant - proteins bonding used the dialysis techniques. Other techniques used to determine the binding isotherm, included ultrafiltration, ultracentrifugation, potentiometry, ...

  9. Environmental study of radioactive caesium in Greek lake fish after the Chernobyl accident

    International Nuclear Information System (INIS)

    The radiological status of radiocaesium in the Greek environment until 1986 has been characterized by the impact of world-wide fallout. During 1986, the Chernobyl nuclear accident resulted in an average deposition of total caesium(134Cs + 137Cs) of ∼ 9 kBq m-2 in Greece, while regional averages ranged within 3-45 kBq m-2. The radioactive contamination of the lake ecosystems is potentially a radiologically important consequence of the accident. The effects of 137Cs and 134Cs introduced into a number of major Greek lake ecosystems has been evaluated in the present work by determination of their concentrations in various lake fish species during the years 1986, 1988 and 1989. Although the representative and predominant species typically differ from lake to lake, while the local deposition of caesium varies significantly, the bioaccumulation of caesium by the examined species seems to depend rather on the fish species than on the local environmental parameters. The time-dependence of the fish contamination has been used to evaluate the contribution of lake fish consumption to the total ingestion dose of the population. (author)

  10. The use of the tracer caesium-137 for studying sediment movement in a drainage basin

    International Nuclear Information System (INIS)

    The environmental isotope caesium-137 (137Cs), a product of atmospheric nuclear weapons tests, was used as a tracer to assess sediment sources and sediment redistribution in the drainage of Maluna Creek, Hunter Valley, New South Wales. Caesium-137 levels were found to be significantly different between the three main land-use groups of forest, grassland and vines. Caesium-137 amounts per unit area were greatest in the forest and least in cultivated vineyards, and were attributed to accelerated soil erosion from cultivated areas. Soil losses from four runoff plots correlated positively with the loss of 137Cs (in relation to estimated input) in soils adjacent to the plots. Relative amounts of 137Cs in soil profiles in a northern tributary basin of Maluna Creek were used to trace eroded soils from vineyards to sedimentation sites in adjacent alluvial fans and a downstream farm dam reservoir. The redistribution of 137Cs in the sedimentary deposits was related to particle size, the greatest amounts of the isotope being found on finer sediments in the reservoir

  11. The Time Analysis and Frequency Distribution of Caesium-137 Fall-Out in Muscle Samples

    International Nuclear Information System (INIS)

    For low concentrations of artificial radioactivity in the body, detrimental effect will be most likely in that fraction of the population having many times the average amount. A meaningful evaluation of the nuclear fall-out hazard can only be made if the frequency distribution of radioactivity in the population is known. Attempts to determine the shape of the distribution curve from Kulp's data on strontium-90 concentration in children's bones have met limited success because of the small sample size and lack of strontium-90-calcium equilibrium in bone. To overcome these limitations, we have measured the caesium-137 content in approximately 900 muscle samples. These tissue samples were removed during post-mortem operations from January 1959 to August 1963. The use of caesium-137 as a fission product monitor assures that all members of the group, regardless of their age, were essentially in equilibrium with the radioactive environment at the time of death. The period of investigation coincides with the first weapon test moratorium and the resumption of large- scale testing in the fall of 1961. Average caesium-137 in the samples was relatively constant throughout 1959, decreased a factor of two during 1960, and remained relatively stable until the early summer of 1962. Since mid-1962 the average level of caesium-137 radioactivity in the sample population has steadily increased and was four times greater than the 1962 minimum by the summer of 1963. Time-independent histograms of the data have been assembled by fitting a polynomial to the raw data (sample radioactivity as a function of data of death). This pooled data has been tested statistically against normal, log-normal, and gamma frequency distributions. Results indicate that the experimental distribution is definitely not Gaussian and is best fitted by a gamma distribution. By using the empirically derived gamma distribution it is possible to predict the fraction of the population having N times the average

  12. Vortex migration in protoplanetary discs

    Directory of Open Access Journals (Sweden)

    Papaloizou John C. B.

    2013-04-01

    Full Text Available Vortices embedded in protoplanetary discs can act as obstacles to the unperturbed disc flow. The resulting velocity perturbations propagate away from the vortex in the form of density waves that transport angular momentum. Any asymmetry between the inner and the outer density wave means that the region around the vortex has to change its angular momentum. We find that this leads to orbital migration of the vortex. Asymmetric waves always arise except in the case of a disc with constant pressure, for isothermal as well as non-isothermal discs. Depending on the size and strength of the vortex, the resulting migration time scales can be as short as a few thousand orbits.

  13. Isothermal Titration Calorimetry of RNA

    OpenAIRE

    Salim, Nilshad N.; Feig, Andrew L.

    2008-01-01

    Isothermal titration calorimetry (ITC) is a fast and robust method to study the physical basis of molecular interactions. A single well-designed experiment can provide complete thermodynamic characterization of a binding reaction, including Ka, ΔG, ΔH, ΔS and reaction stoichiometry (n). Repeating the experiment at different temperatures allows determination of the heat capacity change (ΔCP) of the interaction. Modern calorimeters are sensitive enough to probe even weak biological interactions...

  14. The determination of caesium and silver in soil and fungal fruiting bodies by electrothermal atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Methods have been developed for the determination of caesium and silver in soil and fungal samples by microwave-assisted aqua regia digestion, followed by electrothermal atomic absorption spectrometry. The procedure was found to be repeatable (for soil, RSD -1, respectively, and for fungi, RSD -1, respectively) and reasonably efficient. Silver was recovered quantitatively from reference soils, but only about 80-85% of the caesium present could be extracted. Poorer caesium recoveries (< 70%) were obtained if, as part of the sample preparation procedure, solutions were taken to dryness in glass beakers prior to analysis. The detection limits were 0.02 mg Ag and 0.09 mg Cs per gram of dry soil, which are adequate for the determination of the analytes at typical environmental levels. The methods were applied in the analysis of three types of soil, a peaty podzol, a clay loam and a sandy loam and no significant matrix interferences were observed except in the determination of caesium in the sandy loam. For caesium, non-linear response curves, thought to be due to ionisation interference, were encountered using one atomic absorption spectrometer, but were not observed with the other instrument

  15. An experimental study on the possibilities of direct transfer of caesium 137 from sediment to the carps (Cyprinus carpio L.)

    International Nuclear Information System (INIS)

    The exchanges of caesium 137 with the Rhone river water and deposits and its direct transfer from water and deposits to the carp are studied. The sediments have a high retention capacity for radiocaesium associated with fine particles and certain clays (illite). Caesium desorption from sediment to water is always very weak (less than 5% of the initial activity of the sediments); it varies with the agitation and salinity of the water. The transfer of caesium from the water to the carps is characterized by a regular increase of activity in the fish. After 63 days of experimentation, equilibrium has not been reached, the carp have retained only 1% of the water activity, and their concentration factor is about 4. The transfer of caesium from sediment to the fish is weak but regular. After 79 days of experimentation, equilibrium has not been reached. Less than 1% of the sediments activity is found in the fish; the transfer factor is about 10-3. Because of the high content of caesium 137 in sediments, the activity of the carp is increased and the concentration factor, calculated in relation to the surface water, is greater than 60

  16. Adsorption isotherm special study. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-05-01

    The study was designed to identify methods to determine adsorption applicable to Uranium Mill Tailings Remedial Action (UMTRA) Project sites, and to determine how changes in aquifer conditions affect metal adsorption, resulting retardation factors, and estimated contaminant migration rates. EPA and ASTM procedures were used to estimate sediment sorption of U, As, and Mo under varying groundwater geochemical conditions. Aquifer matrix materials from three distinct locations at the DOE UMTRA Project site in Rifle, CO, were used as the adsorbents under different pH conditions; these conditions stimulated geochemical environments under the tailings, near the tailings, and downgradient from the tailings. Grain size, total surface area, bulk and clay mineralogy, and petrography of the sediments were characterized. U and Mo yielded linear isotherms, while As had nonlinear ones. U and Mo were adsorbed strongly on sediments acidified to levels similar to tailings leachate. Changes in pH had much less effect on As adsorption. Mo was adsorbed very little at pH 7-7.3, U was weakly sorbed, and As was moderately sorbed. Velocities were estimated for metal transport at different pHs. Results show that the aquifer materials must be characterized to estimate metal transport velocities in aquifers and to develop groundwater restoration strategies for the UMTRA project.

  17. Adsorption isotherm special study. Final report

    International Nuclear Information System (INIS)

    The study was designed to identify methods to determine adsorption applicable to Uranium Mill Tailings Remedial Action (UMTRA) Project sites, and to determine how changes in aquifer conditions affect metal adsorption, resulting retardation factors, and estimated contaminant migration rates. EPA and ASTM procedures were used to estimate sediment sorption of U, As, and Mo under varying groundwater geochemical conditions. Aquifer matrix materials from three distinct locations at the DOE UMTRA Project site in Rifle, CO, were used as the adsorbents under different pH conditions; these conditions stimulated geochemical environments under the tailings, near the tailings, and downgradient from the tailings. Grain size, total surface area, bulk and clay mineralogy, and petrography of the sediments were characterized. U and Mo yielded linear isotherms, while As had nonlinear ones. U and Mo were adsorbed strongly on sediments acidified to levels similar to tailings leachate. Changes in pH had much less effect on As adsorption. Mo was adsorbed very little at pH 7-7.3, U was weakly sorbed, and As was moderately sorbed. Velocities were estimated for metal transport at different pHs. Results show that the aquifer materials must be characterized to estimate metal transport velocities in aquifers and to develop groundwater restoration strategies for the UMTRA project

  18. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Directory of Open Access Journals (Sweden)

    Sposito Garrison

    2002-09-01

    Full Text Available 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.

  19. Studies on an araldite-based membrane of copper hexacyanoferrate (III) as a caesium ion-sensitive electrode

    International Nuclear Information System (INIS)

    Solid membranes of copper hexacyanoferrate (III) in araldite are evaluated as a caesium ion-sensitive electrode. The electrode can be used for caesium determination in the concentration range of 10-1 to 10-4M. The potentials generated across the membrane are reproducible and steady potentials are attained in about 1 to 2 min. The same electrode can be used over a period of 6 months without significant change in potential. The electrode can be used in the pH ranges 2.5 to 6.0 at 10-2M Cs+ and 3.0 to 6.0 at 10-3M Cs+, and in presence of a number of interfering ions. Potentiometric titration of caesium nitrate with 12-molybdophosphoric acid was also carried out using the membrane as an end point indicator. (author)

  20. Caesium 137: Properties and biological effects resulting of an internal contamination

    International Nuclear Information System (INIS)

    Caesium-137 (137Cs) is a radionuclide present in the environment mainly as the result of the atmospheric nuclear weapons testing and accidents arising in nuclear power plants like the Chernobyl accident in 1986. Nowadays, the health consequences resulting from a chronic exposure to this radionuclide remain unknown. After absorption, the caesium is distributed relatively homogeneously within the body, with a more important load in children than in adults. The toxicity of 137Cs is mainly due to its radiological properties. A high dose of 137Cs is responsible for a medullar dystrophy, disorders of the reproductive function, and effects on liver and renal functions. Disorders of bone mineralization and brain damages were also described in human beings. At lowest dose, 137Cs induces disturbances of wakefulness-sleep cycle, but not accompanied with behavioural disorders. The cardiovascular system was also perturbed. Biological effects of 137Cs on the metabolisms of the vitamin D, cholesterol and steroid hormones were described, but do not lead to clinical symptoms. In human beings, 137Cs leads to an immune deficiency, congenital and foetal deformations, an increased of thyroid cancer, as well as neurological disorders. It seems that children are more sensitive to the toxic effects of caesium than the adults. At present, the only effective treatment for the decorporation of the ingested 137Cs is the Prussian Blue (Radiogardase). The use of pectin to de-corporate the ingested 137Cs, in children notably, is sometimes proposed, but its administration still remains an open question. To conclude, the available scientific data suggest that 137Cs could affect a number of physiological and metabolic functions and consequently, could participate in the health risks associated to the presence of other contaminants in the environment. (authors)

  1. Absorption spectroscopy of cold caesium atoms confined in a magneto-optical trap

    Institute of Scientific and Technical Information of China (English)

    Yan Shu-Bin; Liu Tao; Geng Tao; Zhang Tian-Cai; Peng Kun-Chi; Wang Jun-Min

    2004-01-01

    Absorption spectra of cold caesium atoms confined in a magneto-optical trap are measured around D2 line at 852nm with a weak probe beam. Absorption reduction dip due to electromagnetically induced transparency (EIT)effect induced by the cooling/trapping field in a V-type three-level system and a gain peak near the cycling transition are clearly observed. Several mechanisms mixed with EIT effect in a normal V-type three-level system are briefly discussed. A simple theoretical analysis based on a dressed-state model is presented for interpretation of the absorption spectra.

  2. Isolation and identification of cobalt and caesium resistant bacteria from a nuclear fuel storage pond.

    OpenAIRE

    Dekker, L.; Osborne, T. H.; Santini, J. M.

    2014-01-01

    One of the issues facing the nuclear power industry is how to store spent nuclear fuel which is contaminated with radionuclides produced during nuclear fission, including caesium ((134) Cs(+) , (135) Cs(+) and (137) Cs(+) ) and cobalt ((60) Co(2+) ). In this study we have isolated Co(2+) and Cs(+) resistant bacteria from water collected from a nuclear fuel storage pond. The most resistant Cs(+) and Co(2+) isolates grew in the presence of 500 mM CsCl and 3 mM CoCl2 . Strain Cs67-2 is resistant...

  3. Alteration in caesium behavior in rice caused by the potassium, phosphorous, and nitrogen deficiency

    International Nuclear Information System (INIS)

    The physiological effects of critical nutrient deficiencies (K, P, N) on the uptake of caesium (Cs) and impact on plant growth has been investigated in rice plants. Growth defects were observed after 2 weeks of a state of nutrient starvation (K, P, or N). However, only K starvation produced increased Cs content in the shoot and the intensive transport to young leaves. These observations support that modification of Cs uptake and transport in rice plants was achieved based on the distinctive physiological effect of K. (author)

  4. A possible role of caesium radiations in the control of propagation of hookworm

    International Nuclear Information System (INIS)

    Faeces charcoal mixtures containing eggs of sheep hookworm, Haemonelus ocatorus were exposed to caesium radiation (23 r to 1656 r) from 1st to 7th day incubation. Each plate was exposed only once. A dose related inhibition of transformation of eggs to infective larvae was observed. The maximum effect was observed on 2nd day of incubation. The radiation has maximum effect on the 1st stage larvae followed by 2nd stage. The 3rd stage or infective larvae are relatively resistant to the effect of radiation. (author). 14 refs

  5. Poly[μ3-aqua-aqua-μ5-(4-nitro­benzoato)-caesium

    OpenAIRE

    Graham Smith

    2013-01-01

    In the structure of the title complex, [Cs(C7H4NO2)(H2O)2]n, the caesium salt of 4-nitrobenzoic acid, the irregular CsO9 coordination sphere comprises three bridging nitro O-atom donors, a bidentate carboxylate O,O′-chelate interaction, a triple-bridging water molecule and a monodentate water molecule. A three-dimensional framework polymer is generated, within which there are water–carboxylate O—H...O and water–water O—H...O hydrogen-bonding interactions.

  6. Patients blood serum ferritin concentrations changes associated with Caesium-137 incorporation

    International Nuclear Information System (INIS)

    The results of radioimmune study of ferritin and carcinoembryonic antigen in 60 persons: 35 those who took part in liquidation of the Chernobyl accident and incorporated 25.9-70.4 MBq of Cesium-137,25 residents of Rivno Region with 7.4-203.5 MBq of the radionuclide in the organism are reported. The increased concentration of ferritin and carcinoembryonic antigen in blood serum was noted to be determined more often in the residents of the areas polluted with Caesium-137 than in liquidators. The tumor markers levels depended to some extent on bad habits (smoking, alcohol) and existing chronic diseases of the alimentary system

  7. A facility for the production of 123I by spallation of caesium

    International Nuclear Information System (INIS)

    An on-line facility for the production of 123I by spallation of elemental caesium by 482 MeV protons has been in operation at a TRIUMF beam dump for about two years. Radioxenon from the target is efficiently trapped on alumina which is subsequently used to remove the 121Te decay product. The yield is 100 mCi/h from a 20 g/cm2 target at 10 μA. Impurities are 125I 121Te 123I consists mainly of iodide along with significant iodate impurity. The product is used extensively in Canadian clinics for thyroid analyses and labelling radiopharmaceuticals. (auth)

  8. Isothermal Shock Wave in Magnetogasdynamics

    OpenAIRE

    B. G. Verma; J. P. Vishwakarma; Vishnu Sharan

    1983-01-01

    The problem of propagation of a plane isothermal discontinuity (shock) wave in a homogeneous semi-infinite body of a perfect gas, in the presence of amagnetic field have been solved. It has been shown that under certain definiteconditions, the density p at the wave front may be arbitrarily high for a singlecompression pulse. A certain class of solutions of the present problem for a nonhomogeneous semi-infinite body have been derived. Such solutions are expected to be of great importance in co...

  9. Biosorption isotherm for uranium recovery

    International Nuclear Information System (INIS)

    An analysis of the biological sorption of uranium on mycelia of Penicillium C-1 is provided. From an isotherm test, a rough estimate of the biomass, required for removal of uranium to a certain level can be attained. The process presents a new approach towards water pollution control and resource recovery. The biosorption method may find its greatest application in solutions of low uranium concentration (100 ppM to 300 ppM) such as in waste mine water or very lean leach solutions

  10. Effects of sorption behaviour on contaminant migration

    International Nuclear Information System (INIS)

    The effects of sorption behaviour on contaminant migration in groundwater systems are varied. Retardation of migration and dispersive effects can vary widely and contaminant concentration profiles can take a number of different shapes. This report examines the nature of some of these effects, especially those due to sorption behaviours that are dependent on the concentration of the contaminant in the groundwater. The effects are calculated using, in most cases, analytical solutions to the chemical equations imbedded in a simple reaction-cell or box-model transport algorithm. The hydrogeological parameters are held constant, and radioactive decay and hydrodynamic dispersion are excluded. A general discussion of the role of sorption equations in transport modelling is followed by presentation of migration results for a number of models of sorption behaviour varying from linear isotherms, Langmuir, Freundlich and ion-exchange isotherms, to precipitation reactions and multiple-site sorption reactions. The results are compared and general conclusions are drawn about the various migration behaviours calculated. The conclusions are that equilibrium sorption of trace contaminants can be modelled with linear isotherms (constant distribution coefficients or constant retardation factors) but the evaluation and extrapolation of the distribution coefficient are not easy. Nonlinear isotherms lead to unsymmetrical migration fronts. A comparison of Freundlich and linear isotherms is made. Sorption/desorption kinetic factors can be significant on the time scale of laboratory experiments and can cause large dispersive effects. Slow but important reactions can be missed altogether. Precipitation or mineralization behaviour cannot be modelled with constant distribution coefficients. Also, mineralization reactions can be kinetically slow even on the geological time scale. 89 refs

  11. Room temperature isotherms for Mo and Ni

    International Nuclear Information System (INIS)

    Isotherms at room temperature for Mo and Ni are proposed. They are of three types: BIRCH, KEANE and BORN-MIE. The adjustable constants appearing in these isotherms have been determined from experimental quantities at zero pressure. An evaluation of the limit of (δBT/δP)T as P #-> # ∞, where BT is the isothermal bulk modulus, has been also used. These three isotherms obtained for Mo and Ni are compared with isotherms derived from shock-wave data according to the PRIETO's model. There is a good agreement between these and these derived from shock-wave data. The three isotherms proposed for Mo and Ni can be considered as valid until pressures of several BTo, where BTo is the bulk modulus BT at P = o

  12. Caesium-137 and sediment budgeting within a partially closed drainage basin

    International Nuclear Information System (INIS)

    Caesium-137 (137Cs) when combined with landform element analysis and sediment budgeting provides a powerful geomorphological tool in studies of erosion. Application of the 137Cs technique to a partially closed cultivated drainage basin in Saskatchewan, Canada, allowed for the identification of eroded areas, zones of stability, and depositional areas. Sediment redistribution was calculated for a 30 year period and indicated that 68% of the sites had experienced accelerated erosion rates in excess of soil formation rates (1.0 t ha-1 yr-1) 47% of the sites had rates in excess of 5.0 t ha-1 yr-1, and 14% of the sites had erosion rates greater than the upper tolerable soil loss boundary of 11.0 ha-1 yr-1. A digital elevation model indicated that eroded sites primarily had convex (divergent) shapes. These areas were also characterized by thin A-horizons, decreased total nitrogen percent, and thin zones of CaCO3 depletion. Caesium-137 and sediment budgeting indicated that there was a minor net loss of 137Cs and sediment from the partially closed basin and this was attributed to aeolian transport, which is generally ignored in 'closed' basin studies. (orig./BBR)

  13. The deposition of Chernobyl caesium-137 in heavy rain and its persistent uptake by grazing sheep

    International Nuclear Information System (INIS)

    Activity escaped from the wrecked reactor at Chernobyl for 10 days and spread over most of Europe. Part of the debris crossed Britain a week after it was emitted. Heavy thunderstorms and a northward-moving cold front washed out much of the radioactive iodine and caesium it carried, especially on to the upland areas of North Wales, northern England, SW Scotland and Ulster. Several lessons have been learnt, including information on the dry and wet removal rates. The deposition of Chernobyl debris was of transient importance to agriculture in lowland areas which are rich in clay minerals. There, levels of iodine-131 in milk in the 2 weeks following the debris' passage over the country were readily detected, even though the levels were well below Government limits, but fell to insignificance thereafter. In contrast, in upland sheep-rearing areas, the caesium has remained mobile in the acidic soils and levels in sheep have often exceeded Government limits, and have been decreasing only slowly since 1986

  14. Factors influencing caesium-137 levels in moose (Alces alces) and small game in Northern Sweden

    International Nuclear Information System (INIS)

    In the third annual hunting season after the Chernobyl accident the concentration of Cs-137 in meat of northern Swedish moose was significantly higher than in the first one (1986). In September 1986 the mean Cs concentration was 500 Bq/kg in calves but in September 1988 it has risen 1300 Bq/kg. This increase was only temporary and a rapid decline occured after September and by December 1988 the concentration of Cs was the same as in late 1986. Adult moose showed the same increase during the hunt 1988 but to a lower magnitude. Typical food plants of moose such as bilberry (Vaccinum myrtillus) and birch (Betula pubescens) showed, contradictory to expected by the level in moose, a decline of concentration caesium from 1986 to 1988. A probable explanation to the dramatically increased concentration of Cs in moose is a change in diet selection during 1988. Small mammals such as voles and lemmings showed a variation in concentration of caesium-137 which was more dependent on other factors than on their body size. This emphasize the necessity to study diet selection by herbivores in detail in order to predict uptake and changes in environmental contaminants. (orig.)

  15. Adiabatic Theorems and Reversible Isothermal Processes

    CERN Document Server

    Abou-Salem, W K

    2005-01-01

    Reversible isothermal processes of a finitely extended, driven quantum system in contact with an infinite heat bath are studied from the point of view of quantum statistical mechanics. Notions like heat flux, work and entropy are defined for trajectories of states close to, but distinct from states of joint thermal equilibrium. A theorem characterizing reversible isothermal processes as quasi-static processes ("isothermal theorem") is described. Corollaries concerning the changes of entropy and free energy in reversible isothermal processes and on the 0th law of thermodynamics are outlined.

  16. Hydroxyapatite supported caesium carbonate as a new recyclable solid base catalyst for the Knoevenagel condensation in water

    OpenAIRE

    Monika Gupta; Rajive Gupta; Medha Anand

    2009-01-01

    The Knoevenagel condensation between aromatic aldehydes and malononitrile, ethyl cyanoacetate or malonic acid with hydroxyapatite supported caesium carbonate in water is described. HAP–Cs2CO3 was found to be a highly active, stable and recyclable catalyst under the reaction conditions.

  17. Use of caesium-137 as a tracer of erosion and sedimentation: Handbook for the application of the caesium-137 technique. UK Overseas Development Administration research scheme R4579

    International Nuclear Information System (INIS)

    The caesium 137 technique has become an important tool for investigating soil erosion. It permits retrospective assessment of medium-term erosion rates. The application of the technique requires only one field visit, and the results can be provided within a relatively short time. The soil redistribution rates estimated represent an average for the last 30-35 years, and are therefore less influenced by extreme events. The rates estimated represent the sum of all erosive processes. Both rates and patterns of soil redistribution may be quantitatively assessed. A range of erosion estimates may be obtained, including mean rates of erosion and deposition and net rates of soil export from the field. The whole field may be studied without disturbance to the slope environment. The spatial resolution of the data obtained is defined by the sampling strategy. Chapters of part 1 discuss the basis of the 137Cs technique, the potential for its further development, and define a protocol for its application. Part 2 includes descriptions of case studies from China, Zimbabwe and Lesotho, which illustrate the value of the 137Cs technique in the assessment of soil erosion

  18. Migration peculiarities of long-lived radionuclides in soils in areas contaminated by the Chernobyl NPP accident

    International Nuclear Information System (INIS)

    We studied migration of long-lived radionuclides of caesium-134/137, cerium-144 and ruthenium-106 in soil samples from regions contaminated by the Chernobyl accident. Samples of three types of contamination - fuel (A), quasi-fuel (B) and aerosol (C) - were taken at calibration sites in August 1988 down to a depth of 5 cm using conventional core samplers. The radioactivity of the samples was measured at intervals of 0.5 cm, as was the activity of three mechanical fractions of the samples: 1-2 (> 2) mm; 0.25-1.0 mm; 2) mm fractions (grass, roots and tillering nodes) in the 0-1 (to 2) cm layer, which reflects the increasing role of biogenic migration processes in mass transfer of radionuclides despite their apparent lack of mobility in biocenoses. The soil's dust and clay fraction (< 0.25 mm) helps to fix the radionuclides in the crystal structures of soil minerals and organic matter. The ratio of caesium-134/caesium-137 in soils exhibiting the quasi-fuel type of contamination varies from 0.17-0.55 in the 1-2 mm and < 0.25 mm sample fractions, evidently reflecting the various radionuclide occurrence forms and topographies in the fallout matrix, isotope separation included. (author)

  19. Specific features of 137Cs migration and accumulation in chernozem soils of forest ecosystems in the zone contaminated due to the Chornobyl accident

    International Nuclear Information System (INIS)

    A number of factors influencing 137Cs fate and biological availability in chernozem soils under the forest vegetation were assessed for various climatic zones. The migration rates of 137Cs in the profile of chernozem soils were shown to depend primary on forest litter composition and structure. In the absence of forest litter the soil mineralogical composition and humus content become the most influential factors of caesium mobility

  20. Isothermal air ingress validation experiments

    International Nuclear Information System (INIS)

    Idaho National Laboratory carried out air ingress experiments as part of validating computational fluid dynamics (CFD) calculations. An isothermal test loop was designed and set to understand the stratified-flow phenomenon, which is important as the initial air flow into the lower plenum of the very high temperature gas cooled reactor (VHTR) when a large break loss-of-coolant accident occurs. The unique flow characteristics were focused on the VHTR air-ingress accident, in particular, the flow visualization of the stratified flow in the inlet pipe to the vessel lower plenum of the General Atomic's Gas Turbine-Modular Helium Reactor (GT-MHR). Brine and sucrose were used as heavy fluids, and water was used to represent a light fluid, which mimics a counter current flow due to the density difference between the stimulant fluids. The density ratios were changed between 0.87 and 0.98. This experiment clearly showed that a stratified flow between simulant fluids was established even for very small density differences. The CFD calculations were compared with experimental data. A grid sensitivity study on CFD models was also performed using the Richardson extrapolation and the grid convergence index method for the numerical accuracy of CFD calculations . As a result, the calculated current speed showed very good agreement with the experimental data, indicating that the current CFD methods are suitable for predicting density gradient stratified flow phenomena in the air-ingress accident. (author)

  1. ISOTHERMAL AIR INGRESS VALIDATION EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Chang H Oh; Eung S Kim

    2011-09-01

    Idaho National Laboratory carried out air ingress experiments as part of validating computational fluid dynamics (CFD) calculations. An isothermal test loop was designed and set to understand the stratified-flow phenomenon, which is important as the initial air flow into the lower plenum of the very high temperature gas cooled reactor (VHTR) when a large break loss-of-coolant accident occurs. The unique flow characteristics were focused on the VHTR air-ingress accident, in particular, the flow visualization of the stratified flow in the inlet pipe to the vessel lower plenum of the General Atomic’s Gas Turbine-Modular Helium Reactor (GT-MHR). Brine and sucrose were used as heavy fluids, and water was used to represent a light fluid, which mimics a counter current flow due to the density difference between the stimulant fluids. The density ratios were changed between 0.87 and 0.98. This experiment clearly showed that a stratified flow between simulant fluids was established even for very small density differences. The CFD calculations were compared with experimental data. A grid sensitivity study on CFD models was also performed using the Richardson extrapolation and the grid convergence index method for the numerical accuracy of CFD calculations . As a result, the calculated current speed showed very good agreement with the experimental data, indicating that the current CFD methods are suitable for predicting density gradient stratified flow phenomena in the air-ingress accident.

  2. Can inter-cultivar variation in caesium and strontium uptake reduce contamination of forage grasses? - Can inter-cultivar variation in caesium and strontium accumulation by forage grasses be used to reduce contamination of cows' milk in radiologically contaminated areas?

    International Nuclear Information System (INIS)

    Radiocaesium and radiostrontium primarily enter the food chain via plant root uptake, including indirectly via animal fodders. Inter-species variation in caesium and strontium accumulation in plants has previously been reported to be over two orders of magnitude. This variation could be exploited to select crops with relatively low uptake to reduce transfer of these radionuclides to consumers in contaminated areas. Exploiting intra-species (i.e. inter-cultivar) variation in caesium and strontium uptake has not yet been evaluated as a remediation strategy as sufficient data have not been available. As cows' milk has been one of the main contributors to human dose following the Chernobyl and Mayak accidents, we have chosen to focus on elucidating the extent and nature of inter-cultivar variation in caesium and strontium uptake in forage grasses. A total of 412 cultivars from four species of forage grass; perennial ryegrass (Lolium perenne; 284 cultivars), Italian ryegrass (Lolium multiflorum; 17 cultivars), hybrid ryegrass (Lolium hybridum; 101 cultivars) and tall fescue (Festuca arundinacea; 10 cultivars) were sampled from 20 sets of experimental plots in Aberystwyth (Wales, UK) and Edinburgh (Scotland, UK). Fifty-nine cultivars were grown in both locations. At least three replicates of the same cultivar were grown in each set of plots. Vegetation samples from 2208 plots were collected both in spring 2013 (May-June) and summer 2013 (August-September). The samples were oven-dried and milled then analysed for elemental composition using inductively coupled plasma mass spectrometry (ICP-MS). Stable caesium and strontium were measured as a proxy measurement for radiocaesium and radiostrontium concentrations. Concentrations of chemical analogues of caesium and strontium (potassium and calcium) and a number of other elements were measured. Soil samples from the experimental plots were also collected, dried, milled and analysed using ICP-MS. This paper will present the

  3. Medical migration.

    Science.gov (United States)

    Loefler, I J

    2001-10-01

    The issue of professional migration, however emotional it may have become, ought not to be regarded in moralizing terms. The history of western medicine is the history of migrating physicians. A doctor who moves from a locality to another to take up a new assignment there cannot be said to have "abandoned his patients". This emotional bond has become the victim of specialization and of depersonalization of medical services and not of medical migration, brain drain or otherwise. The primary reason for medical migration is not financial; the desire to migrate usually begins with the desire to learn. Professionals crave in the first line for professional satisfaction. The migration of medical manpower cannot be stopped with administrative measures and will not be stopped by exhortations and appeals, moralization and condemnations. Brain drain is a global phenomenon and has always been so. A country which loses its professionals, its doctors, should examine the social relationships within the profession and should investigate whether the opportunities for deriving professional satisfaction from everyday work exist or whether these have been thwarted by the hierarchy, conservatism, cronyism and the general lack of comprehension of what good medical care is about. PMID:11593497

  4. Migration chemistry

    International Nuclear Information System (INIS)

    Migration chemistry, the influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour of pollutants in the environment, is an interplay between the actual natur of the pollutant and the characteristics of the environment, such as pH, redox conditions and organic matter content. The wide selection of possible pollutants in combination with varying geological media, as well as the operation of different chemical -, biochemical - and physico-chemical reactions compleactes the prediction of the influence of these processes on the mobility of pollutants. The report summarizes a wide range of potential pollutants in the terrestrial environment as well as a variety of chemical -, biochemical - and physico-chemical reactions, which can be expected to influence the migration behaviour, comprising diffusion, dispersion, convection, sorption/desorption, precipitation/dissolution, transformations/degradations, biochemical reactions and complex formation. The latter comprises the complexation of metal ions as well as non-polar organics to naturally occurring organic macromolecules. The influence of the single types of processes on the migration process is elucidated based on theoretical studies. The influence of chemical -, biochemical - and physico-chemical reactions on the migration behaviour is unambiguous, as the processes apparently control the transport of pollutants in the terrestrial environment. As the simple, conventional KD concept breaks down, it is suggested that the migration process should be described in terms of the alternative concepts chemical dispersion, average-elution-time and effective retention. (AB) (134 refs.)

  5. Caesium carbonate as a highly efficient catalyst for the synthesis of macrocyclicdiamides

    Directory of Open Access Journals (Sweden)

    Esmael Rostami

    2014-07-01

    Full Text Available In this research work, we report the synthesis of macrocyclicdiamides from the reaction of diesters and aliphatic diamines in the presence of caesium carbonate. It has been demonstrated that among the carbonate of alkali metals (Li2CO3, Na2CO3, K2CO3 and CS2CO3, CS2CO3 appears to be the best catalyst for macrocyclization. Diesters with different substitution patterns on the aromatic ring reacted smoothly with diamines under optimal conditions, affording the corresponding macrocycles in high yields. Introducing a rigid group (e.g., sulfone on the substrate led to somewhat decreased yield. Various substrates proved to be suitable for this macrocyclization reaction, especially, the flexible ones.

  6. Caesium Radionuclide Uptake from Wet Soil to Kangkung Plant (Ipomoea sp)

    International Nuclear Information System (INIS)

    Caesium radionuclide transfer from soil to kangkung plant (Ipomoea sp) generally consumed by people had been examined to obtain transfer factor value for internal radiation dose assessment via soil-plant-human pathway. The kangkung plants were cultivated on watered soil medium containing 134Cs with concentration of about 80 Bq/g, and the 134Cs uptake by plants, i.e root, stem, and leaves, were measured using gamma spectrometer. The 134Cs plant uptake was expressed as transfer factor, i.e. ratio of plant 134Cs concentration to 134Cs concentration on soil medium. From this research it was obtained transfer factor value of 134C from soil to plant is 0.07, and the transfer factor for root, stem, and leaves are 0.34 ; 0.05 ; 0,03 respectively, after 45 days cultivation. The transfer factor values are less than one, indicate that kangkung plant do not accumulate Cs radionuclide from soil. (author)

  7. Synthetic crystalline calcium silicate hydrate (I): cation exchange and caesium selectivity

    International Nuclear Information System (INIS)

    Solid crystalline calcium silicate hydrate (I) synthesized from equimolar amounts of Ca and Si under hydrothermal conditions at 120 oC shows cation exchange properties towards divalent metal cations such as Ni, Cu, Cd, or Hg. It also exhibits caesium selectivity in the presence of Na+. The exchange capacity and selectivity of the solid can be increased by 10 and 28 %, respectively, upon substitution of 0.01 mol of the Ca2+ in its structure by Na+. The ability of metal cation uptake by the solid was found to obey the order Ni2+ > Hg2+ > Cu2+ > Cd2+. The different affinities of calcium silicate hydrate (I) towards these ions can be used for their separation from solutions and also in nuclear waste treatment. The mechanism of the exchange reaction is discussed. (author)

  8. Promoting the conversion of caesium phospho-molybdate to zirconium molybdate

    International Nuclear Information System (INIS)

    During the management of Highly Active Liquors precipitation of caesium phospho-molybdate occurs. It was recently discovered that this solid can convert to another solid, zirconium molybdate. under certain process conditions This contribution focuses on the background chemistry to molybdates in high acid media, various chemical factors that have been considered for effecting the conversion rate, along with some experimental results. It has been observed that high temperature and low acidity are favourable to conversion. Other factors such as phosphate levels and concentration lead to an increase in the conversion time. A two-stage mechanism for the conversion has been proposed based on the experimental data and knowledge of molybdate chemistry. (authors)

  9. Redistribution of caesium-137 by erosion and deposition on an australian soil

    International Nuclear Information System (INIS)

    Caesium-137, a nuclear fallout product which is carried down to the ground by rainfall and becomes tightly adsorbed to soil particles, is being used to study soil erosion and accumulation. The measurement of 137Cs activity in soil cores in an upland catchment on the Darling Downs has revealed a vertical and areal distribution of this isotope which is in general agreement with expectations based on the topography, the observed erosion and deposition sites, the variation in 137Cs fallout through time, and hypotheses of 137Cs redistribution. Such information may allow the development of a practical technique for estimating soil erosion and accumulation rates using this isotope; it also allows testing of mathematical models of erosion/deposition processes

  10. Enhanced Raman sideband cooling of caesium atoms in a vapour-loaded magneto-optical trap

    CERN Document Server

    Li, Y; Feng, G; Nute, J; Piano, S; Hackermuller, L; Ma, J; Xiao, L; Jia, S

    2015-01-01

    We report enhanced three-dimensional degenerated Raman sideband cooling (3D DRSC) of caesium (Cs) atoms in a standard single-cell vapour-loading magneto-optical trap. Our improved scheme involves using a separate repumping laser and optimized lattice detuning. We load $1.5 \\times 10^7$ atoms into the Raman lattice with a detuning of -15.5 GHz (to the ground F = 3 state). Enhanced 3D DRSC is used to cool them from 60 $\\mu$K to 1.7 $\\mu$K within 12 ms and the number of obtained atoms is about $1.2 \\times 10^7$. A theoretical model is proposed to simulate the measured number of trapped atoms. The result shows good agreement with the experimental data. The technique paves the way for loading a large number of ultracold Cs atoms into a crossed dipole trap and efficient evaporative cooling in a single-cell system.

  11. Experimental observation of pump-probe spectra of caesium D2 line with a vapour cell

    Institute of Scientific and Technical Information of China (English)

    Wang Yan-Hua; Yang Hai-Jing; Zhang Tian-Cai; Wang Jun-Min

    2005-01-01

    Pump-probe spectra of caesium D2 line are experimentally investigated in a Cs atomic vapour cell with copropagating orthogonal linearly-polarized pump and probe laser beams. Absorption-reduction dips duo to electromagnetically induced transparency (EIT) in multi-A-type Zeeman sublevels of 6 S1/2 F=3-6 P3/2 F'=2 hyperfine transition and absorption-enhanced peaks due to electromagnetically induced absorption (EIA) in 6 S1/2 F=4-6 P3/2 F'=5 hyperfine transition are demonstrated. With detuned pump beam abnormal sign-reversed signals inside the EIT dip and the EIA peak are clearly observed.

  12. Observation of four-wave mixing in caesium atoms using a noncycling transition

    Institute of Scientific and Technical Information of China (English)

    Wang Li-Rong; Ma Jie; Zhao Jian-Ming; Xiao Lian-Tuan; Jia Suo-Tang

    2006-01-01

    In this paper the generation of four-wave mixing (FWM) signal using a noncycling transition of caesium atoms is investigated when the pumping laser is locked to the transition 6S1/2F = 4 → 6P3/2F' = 4, and meanwhile the probe frequency is scanned across the 6S1/2F = 4 → 6P3/2 transition. The efficiency of the four-wave mixing signal as a function of the intensity of the pumping beams and the detuning of the pumping beams is also studied. In order to increase the detection efficiency, a repumping laser which is resonant with 6S1/2F = 3 → 6P3/2F' = 4 transition is used. A theoretical model is also introduced, and the theoretical results are in qualitative agreement with experimental ones.

  13. Monitoring of caesium-137 in food plants and muscle from moose, red deer and wild reindeer in 2010

    International Nuclear Information System (INIS)

    The monitoring of Cs-137 fall-out from the Chernobyl accident in 1986, started the same year. Several plants and wild reindeer in natural ecosystems in Nord-Rondane have been followed annually ever since. Four more wild reindeer ranges were included in 2001: Setesdal-Ryfylkeheiene, Hardangervidda, Nord-Ottadalen, Snoehetta and Nord-Rondane. From 2007 Forollhogna was also included. On fixed plots in Nord-Rondane and Snoehetta some of the reindeer forage plants, including both higher plants and fruticose lichens, have been sampled and analyzed annually since 1986. This was also done in 2010. In addition plants and lichens were sampled at five locations along an altitudinal gradient at Soendre Knutshoe, and at 7-8 locations along an east-west gradient from Kollaflata to Skarhoe in the Jora valley continuing along the Aursjoe to Torbudalen. All these locations were sampled annually between 1987-1990, but they have not been sampled since. In 2010 samples from red deer and moose was also collected from eight different regions located within the following counties: Oppland, Telemark, Vest-Agder, Rogaland, Sogn and Fjordane, Nord-Troendelag, Nordland and Troms. Red deer were sampled in four regions and moose in six. Both species were sampled in Oppland. In 2010 76, 49 and 61 samples were collected from wild reindeer, red deer and moose respectively. All measures of caesium levels were performed on dried samples. For the 596 samples of plants and lichen the results refer to caesium-levels in dried samples. For the meat samples, results refer to caesium-137 levels in raw meat. Due to large variation in measured levels of caesium within species and sampling area, we give median values instead of mean values.The highest caesium levels in wild reindeer were found in Snoehetta (1010 Bq/kg) and Nord-Rondane (2686 Bq/kg). The levels found in the other areas were considerably lower. The highest caesium levels in both red deer (Sel, 677 Bq/kg) and moose (Vaaga, 365 Bq/kg) were found

  14. Effects of potassium fertilization on caesium transfer to grass, barley and vegetables after Chernobyl

    International Nuclear Information System (INIS)

    The fallout in 1986 caused considerable problems on grassland in several Swedish districts. For all agricultural crops in these districts a higher level of potassium fertilization was recommended in 1987. The situation was also under observation on many field sampling and field experimental sites. The latter, which have given data for 1987-1989, were selected in different environments, on organic and on sandy soils, on permanent and temporary grassland and on land used for arable crops as well as for vegetables. Some of them were permanent pastures in the mountain district. The experimental treatments were 0, 50, 100, and 200 kg K per ha. It was found that the highest annual transfer to grass, 4-10% of the total deposition per unit area, occurred on permanent grasslands from one pasture on peat soil and from one pasture in the mountain district. The total transfer to arable crops from peat soil in control treatments was about 0.5% of the total deposition. From the mineral soils the corresponding transfers were about 0.05%. The potassium treatments were effective already on the 50-100 kg level, although 200 kg K per ha gave the highest reduction in total caesium transfer with 60-80% on grassland. The effect was observed already in the 1st cut. In the barley crops the potassium applications caused a relative reduction in caesium transfer to the same extent as on the grassland but on a lower absolute level. Among the vegetables, the order in cesium transfer to the crop took place in the order: Lettuce>Potatoes>Carrots>Leek. (au)

  15. Caesium concentration factors in wild herbivores and the fox (Vulpes vulpes L.)

    International Nuclear Information System (INIS)

    A selection of wild animals was sampled in the winter of 1986/87. The sites chosen for sampling were based on information obtained from surveys carried out by The Institute of Terrestrial Ecology in the spring and autumn of 1986. Animals included deer, grouse, hares and rabbits, and foxes which were collected as a top carnivore in the food chain. Variation in concentration of caesium between species from the same area was unpredictable; rabbits never exceeded 200 Bq kg-1 (fresh wt) of 137Cs in their flesh, even when adjacent to deer forests with over 1000 Bq kg-1 in the venison. The greatest complication arose from areas of peaty uplands where the pre-Chernobyl 137Cs from weapons-testing was much higher than expected. This pre-Chernobyl contribution amounted to 630 Bq kg-1 in a red grouse from the Pennines, and 650 Bq kg-1 in a roe deer from near the Borders, being c. 60% of the total. Significant differences in concentration factors were found depending on species, food, sex, breeding condition and age. Contrasting the decrease of the two caesium isotopes in roe deer from forestry on peat with those from woodlands on mineral soils, it appeared that after an initial fall in concentration, the only decrease thereafter occurred on the mineral soils. Nowhere were radiocaesium concentrations high enough to cause concern amongst consumers of game and other wild animals, even when levels exceed 3000 Bq kg-1 (fresh wt) as they did in red deer, red grouse and the blue hare. (author)

  16. Radionuclide migration in the Chernobyl contamination zone

    International Nuclear Information System (INIS)

    It is well known that the Chernobyl fallout of 137 reaching the land soils with precipitation was rapidly and tightly sorbed to the fine fraction of sediment or soils. The majority of the 137Cs is retained in the top few centimetres of the soil or sediment profiles. In the absence of strong variations in precipitation over a relatively small area the total bomb-derived 137Cs fallout can assumed to be spatial uniform. The Chernobyl 137Cs fallout was mostly connected with one or two rains. So the spatial variability of this 137Cs can be higher. Furthermore because the explosion of the Chernobyl nuclear plant happened together with fire lot of ashes particles with radionuclide were distributed within vast areas. So even microvariability of Chernobyl 137Cs can be very high in some places. The horizontal migration of 137Cs connects with soil erosion processes that dominate on the agricultural lands of the Central Russia. The main goal of this investigation is to evaluate the caesium-137 horizontal and vertical migration within typical landscape of the Central Russia 11 years after the Chernobyl accident. (author). 7 figs., 2 tabs

  17. Radionuclide migration in the Chernobyl contamination zone

    International Nuclear Information System (INIS)

    It is well known that fallout of 137Cs reaching the land soils with precipitation was rapidly and tightly sorbed to the fine fraction of sediment or soils. The majority of the 137Cs is retained in the top few centimetres of the soil or sediment profiles (Loughran et al, 1993, Owens et al, 1996). In the absence of strong variations in precipitation over a relatively small area the total bomb-derived 137Cs fallout can assumed to be spatial uniform. The Chernobyl 137Cs fallout was mostly connected with one or two rains. So the spatial variability of this 137Cs can be higher. Furthermore because the explosion on the Chernobyl nuclear plant happen together with fire, a lot of ashes particles with radionuclide were distributed within vast areas. So even microvariability of Chernobyl 137Cs can be very high in some places. The horizontal migration of 137Cs connects with soil erosion processes that dominate on the agricultural lands of the Central Russia. The main goal of this investigation is to evaluate the caesium-137 horizontal and vertical migration within typical landscape of the Central Russia 11 years after the Chernobyl accident

  18. Applicability of Different Isothermal EOS at Nanomaterials

    OpenAIRE

    Deepika P. Joshi; Anjali Senger

    2013-01-01

    The present study explains the behaviour of nanomaterials such as AlN, CdSe, Ge, WC, and Ni- and Fe-filled-MWCNTs under high pressure. Among the number of isothermal EOSs available, we prefer only two parameter-based isothermal equations (i.e., Murnaghan equation, usual Tait's equation, Suzuki equation and Shanker equation). The present work shows the theoretical study of thermo-elastic properties especially relative compression (V/V0), isothermal bulk modulus (KP/K0), and compressibility (αP...

  19. Reproducing 137Cs vertical migration in Spanish soils - Reproducing 137Cs and 90Sr vertical migration in Spanish mainland

    International Nuclear Information System (INIS)

    As a result of caesium's and strontium's activity migration study developed in Spanish mainland soils, there has been obtained convective - diffusive migration equation that will reproduce adequately the movement that an activity deposit would follow in this land. Taking into account the dependence on rain that apparent convection velocity shows, it has been defined a new migration parameter that depends only on soil's properties. By means of a least square method and fitting the migration equation to experimental activity profiles, the values showed by the migration parameters in the studied soils, characteristics of that area, have been obtained. After that, there have been obtained the mean values of these parameters for each defined group that, depending on soil's texture, have been observed in the study performed about the movement of both radionuclides in soils and to whom these soils belong. Using these mean values and obtained equation, it has been properly reproduce those vertical activity profiles that were experimentally determined. In order to validate these values, a new sampling programme is carrying out in the north of Spain and, with obtained new sampling points' information, is going to verify if, indeed, obtained mean values also reproduce these new sampling points' activity vertical profile. (authors)

  20. Adsorption Isotherms and Surface Reaction Kinetics

    Science.gov (United States)

    Lobo, L. S.; Bernardo, C. A.

    1974-01-01

    Explains an error that occurs in calculating the conditions for a maximum value of a rate expression for a bimolecular reaction. The rate expression is derived using the Langmuir adsorption isotherm to relate gas pressures and corresponding surface coverages. (GS)

  1. Binary Brayton cycle with two isothermal processes

    International Nuclear Information System (INIS)

    Highlights: • This paper presents binary Brayton cycle with two isothermal processes. • Different parameters affecting the cycle performance have been studied. • The present cycle is a promising cycle for future power generation. - Abstract: The literature introduced isothermal concept and binary Brayton cycle as two promising methods used to enhance the performance of the gas turbine. Consequently, this work presents a cycle based on the blending of the two methods. This cycle is composed of gas turbine topping cycle with isothermal combustion and air turbine bottoming cycle with isothermal heating. Different parameters affecting the cycle performance have been studied. Simulations demonstrate that the present cycle achieves drastic enhancement in performance. The cycle merits justify its potential utilization for future power generation

  2. The importance of feeding rate for the accumulation of radioactive caesium in fish after the Chernobyl accident

    International Nuclear Information System (INIS)

    The accumulation of radioactive caesium in roach (Rutilus rutilus) and perch (Perca fluviatilis) was studied in a Swedish forest lake which was heavily contaminated in spring 1986 with fallout from the reactor accident in Chernobyl. During the whole growing season of 1986, the diet, feeding rate and Cs-137 activity in the food (zooplankton) were monitored simultaneously. The activities in small perch were about twice as high as in small roach, although their diet was very similar. This can be explained solely by differences in feeding rates and metabolic activity. By accounting for these factors, the accumulation rate of radioactive caesium in fish during the first growing season after contamination of the lake could be predicted with a simple box model, with feeding rate as one of the most important regulating factors. (au) (23 refs.)

  3. Isothermal calorimeter for reactor radiation dosimetry

    International Nuclear Information System (INIS)

    An isothermal calorimeter with thermistors for measuring absorbed dose rates from 104-5-6.105 rad/h in reactor experimental holes has been designed. A kinetics method for determining the equilibrium temperature difference has been developed, and its application in isothermal calorimetry proved. The expected accuracy in measurements within ± 2-5% has been proved by measurements carried out in the reactor. Some data obtained by measurements in the reactor RA are presented (author)

  4. Radioactive caesium in Boreal forest landscapes - Dynamics and transport in food webs. Summary of research 1986-1996

    International Nuclear Information System (INIS)

    The need for - but also the paucity of - radioecological knowledge concerning the boreal forest became particularly apparent after the nuclear power plant accident in Chernobyl in April 1986. As a consequence several new projects were initiated in the Nordic countries with particular focus on the behaviour of radioactive caesium in terrestrial and aquatic systems characteristic for the Fenno-Scandinavian landscapes. Among these new projects a multi-disciplinary co-operation in Umeaa between scientists at the Swedish University of Agricultural Sciences, and the Defence Research Establishment emerged. Initially this joint work focused mainly on descriptions of the dynamic changes of the content of radioactive caesium in soil-plant and animal communities in the county of Vaesterbotten. Most of the studies have been performed at the Vindeln experimental forest, 60 km NW of Umeaa. Plants of key interest were: bilberry (Vaccinium myrtillus), birch (Betula spp.), and pine (Pinus sylvestris), and among the animals: the moose (Alces alces) and a small rodent, the forest vole (Clethrionomus glareolus). Gradually over the past ten years the research has entered the stage where the specific causes of the caesium behaviour have been addressed - partly by the help of models developed for simulating forest ecosystems, partly by complementary field experiments. This paper reviews our main findings on this theme concerning the behaviour of radioactive caesium in boreal landscapes and significant pathways to man, as has become apparent from the radioecological co-operation dating from about ten years back. A list of the publications arising from these studies since 1986 is also presented in this report

  5. ON THE ISOTHERMALITY OF SOLAR PLASMAS

    International Nuclear Information System (INIS)

    Recent measurements have shown that the quiet unstructured solar corona observed at the solar limb is close to isothermal, at a temperature that does not appear to change over wide areas or with time. Some individual active region loop structures have also been found to be nearly isothermal both along their axis and across their cross section. Even a complex active region observed at the solar limb has been found to be composed of three distinct isothermal plasmas. If confirmed, these results would pose formidable challenges to the current theoretical understanding of the thermal structure and heating of the solar corona. For example, no current theoretical model can explain the excess densities and lifetimes of many observed loops if the loops are in fact isothermal. All of these measurements are based on the so-called emission measure (EM) diagnostic technique that is applied to a set of optically thin lines under the assumption of isothermal plasma. It provides simultaneous measurement of both the temperature and EM. In this work, we develop a new method to quantify the uncertainties in the technique and to rigorously assess its ability to discriminate between isothermal and multithermal plasmas. We define a formal measure of the uncertainty in the EM diagnostic technique that can easily be applied to real data. We here apply it to synthetic data based on a variety of assumed plasma thermal distributions and develop a method to quantitatively assess the degree of multithermality of a plasma.

  6. Internal dosimetry for continuous chronic intake of caesium-137 in cedar pollen after the Fukushima Daiichi nuclear power plant accident

    International Nuclear Information System (INIS)

    Internal exposures of members of the public were assessed for chronic intake of caesium-137 in cedar pollen after the Fukushima Daiichi nuclear power plant accident. Committed effective doses were evaluated using the DSYS-chronic code, which was developed at the Japan Atomic Energy Agency (JAEA). The Activity Median Aerodynamic Diameter (AMAD) and particle density for cedar pollen were assumed to be 32 μm and 0.7 g·cm-3, respectively. The observation period was from early February to the end of May, 2012. It was found that the committed effective doses for adults in Fukushima, Ibaraki, and Tokyo were 1.6-1.8×10-3 μSv, 4.5×10-4 μSv, and 3.0×10-4 μSv, respectively. Hence, it can be stated that internal doses from chronic intake of caesium-137 in cedar pollen were insignificant in 2012. In addition, retention and excretion functions for caesium-137 in the whole body were found to be dependent on the times of intake and the fractional activity related to chronic intake. (author)

  7. Long-term loss rates of radioisotopes of cobalt, zinc, ruthenium, caesium and silver by Mytilus edulis under field conditions

    International Nuclear Information System (INIS)

    Long-term loss rates of cobalt, zinc, ruthenium, caesium and silver by Mytilus edulis soft parts as well as shells were measured under field conditions in the Mediterranean Sea at Monaco during a period of 13 months after experimental contamination. For all 5 elements, the loss could be described by two exponential functions for the soft parts and one for the shells. Biological half lives for the long-lived compartment ranged from ∼20 days for caesium to 100 - 200 days for cobalt, zinc, ruthenium and silver for soft parts as well as for shells. A comparison with results from similar experiments performed under very different environmental conditions in the Baltic Sea indicated that caesium and maybe silver had a faster turnover in the warm and saline Mediterranean, whereas loss rates for cobalt and zinc were comparable. It is argued, that reliable deduction of loss rates require experiments running over several months to a year, and it is pointed out that shorter term experiments - even up to 3 months - may give biased results. (author)

  8. Monarch Migration.

    Science.gov (United States)

    Williamson, Brad; Taylor, Orley

    1996-01-01

    Describes the Monarch Watch program that tracks the migration of the monarch butterfly. Presents activities that introduce students to research and international collaboration between students and researchers. Familiarizes students with monarchs, stimulates their interest, and helps them generate questions that can lead to good research projects.…

  9. Vortex migration in protoplanetary disks

    CERN Document Server

    Paardekooper, S -J; Papaloizou, J C B

    2010-01-01

    We consider the radial migration of vortices in two-dimensional isothermal gaseous disks. We find that a vortex core, orbiting at the local gas velocity, induces velocity perturbations that propagate away from the vortex as density waves. The resulting spiral wave pattern is reminiscent of an embedded planet. There are two main causes for asymmetries in these wakes: geometrical effects tend to favor the outer wave, while a radial vortensity gradient leads to an asymmetric vortex core, which favors the wave at the side that has the lowest density. In the case of asymmetric waves, which we always find except for a disk of constant pressure, there is a net exchange of angular momentum between the vortex and the surrounding disk, which leads to orbital migration of the vortex. Numerical hydrodynamical simulations show that this migration can be very rapid, on a time scale of a few thousand orbits, for vortices with a size comparable to the scale height of the disk. We discuss the possible effects of vortex migrat...

  10. Experimental investigations on the caesium dynamics in H2/D2 low temperature plasmas

    International Nuclear Information System (INIS)

    The fusion experiment ITER requires powerful neutral beam injection (NBI) systems for heating and current drive. The neutral beam with a power of 16.5 MW at an energy of 1 MeV is generated via accelerating negative hydrogen ions and subsequent neutralization in a gas target. A key component of the NBI system is the ion source which has to provide accelerated current densities of 200 A/m2 D- and 300 A/m2 H-. Such ion sources are currently under development and are based on the surface conversion mechanism: atoms and positive ions from a low temperature hydrogen plasma are converted into negative ions at a low work function surface, which is therefore coated with the alkali metal caesium. For that purpose Cs is introduced into the ion source via evaporation from a reservoir. Due to its high chemical reactivity, the adsorbed Cs layer is susceptible to impurities from the residual gas, which degrades the work function of the converter surface. Consequently, the stability and reliability of a high negative ion current density significantly depends on the Cs dynamics in the hydrogen plasma and in the vacuum phases between the pulses. In order to investigate the Cs dynamics on a fundamental level including plasma and surface chemistry, dedicated studies are performed in a flexible laboratory experiment under ion source relevant conditions. The inductively coupled plasma (ICP) setup is equipped with a comprehensive set of diagnostics to measure Cs fluxes, the Cs density, local and global plasma parameters, the work function of a sample surface as well as the impurity content. Owing to the strong Cs dynamics the diagnostics can moreover be applied simultaneously to relate parameters from different diagnostics to the same experimental condition. Furthermore, a reliable Cs source is developed, capable of stable Cs evaporation with well adjustable evaporation rates. The fundamental investigations have emphasized that the Cs dynamics in vacuum as well as in hydrogen and

  11. Caesium-137 distribution, inventories and accumulation history in the Baltic Sea sediments

    International Nuclear Information System (INIS)

    The Baltic Sea is susceptible to pollution by hazardous substances due to limited water exchange, shallowness, and the large catchment area. Radionuclides, particularly 137Cs, are one of the most hazardous anthropogenic substances present in the Baltic environment. This study was conducted to present 137Cs present contamination that should further be a subject of reliable monitoring when the new Nuclear Power Plant is put into operation in the northern Poland. The sea-wide, up to date distribution of 137Cs activities and inventories in the Baltic Sea bottom sediments are presented. The 137Cs activity concentrations were measured in 30 cm long sediment cores collected at 22 sampling stations. Sediment accumulation rates were quantified by 210Pb geochronology to follow the history of 137Cs accumulation. The 137Cs inventories and fluxes were calculated. Most of the Baltic Sea sediments accumulated 137Cs in the range from 750 to 2675 Bq m−2. The Bothnian Bay is severely contaminated by 137Cs with inventories up to 95,191 Bq m−2. This region is moreover characterized by extremely large patchiness of 137Cs inventories. The 137Cs annual fluxes are highest at the two stations located at the Bothnian Bay (342 Bq m−2 and 527 Bq m−2) due to large Chernobyl 137Cs contamination of that region and high sediment accumulation rates. When these stations are excluded, the recent, annual mean value of 137Cs load to the Baltic Sea deposits is 38 ± 22 Bq m−2. The distribution of radio-caesium inventories over the Baltic Sea nowadays reflects the pattern of Chernobyl contamination. The radio-caesium deposited in surface sediments is not permanently buried, but may be resuspended and redeposited by currents, bioturbation or anthropogenic activities. -- Highlights: • 137Cs contamination in the Baltic Sea was studied before the new NPP is put into operation. • Bothnian Sea sediments are severely contaminated by 137Cs (inventories up to 95,191 Bq m−2). • Most of the

  12. Gideon's Migration

    OpenAIRE

    Eagly, Ingrid

    2013-01-01

    For the past fifty years, immigration law has resisted integration of Gideon v.Wainwright’s legacy of appointed counsel for the poor. Today, however, this resistance has given way to Gideon’s migration. At the level of everyday practice, criminal defense attorneys appointed pursuant to Gideon now advise clients on the immigration consequences of convictions, negotiate “immigration safe” plea bargains, defend clients charged with immigration crimes, and, in some model programs, even represent ...

  13. Modeling of Experimental Adsorption Isotherm Data

    Directory of Open Access Journals (Sweden)

    Xunjun Chen

    2015-01-01

    Full Text Available Adsorption is considered to be one of the most effective technologies widely used in global environmental protection areas. Modeling of experimental adsorption isotherm data is an essential way for predicting the mechanisms of adsorption, which will lead to an improvement in the area of adsorption science. In this paper, we employed three isotherm models, namely: Langmuir, Freundlich, and Dubinin-Radushkevich to correlate four sets of experimental adsorption isotherm data, which were obtained by batch tests in lab. The linearized and non-linearized isotherm models were compared and discussed. In order to determine the best fit isotherm model, the correlation coefficient (r2 and standard errors (S.E. for each parameter were used to evaluate the data. The modeling results showed that non-linear Langmuir model could fit the data better than others, with relatively higher r2 values and smaller S.E. The linear Langmuir model had the highest value of r2, however, the maximum adsorption capacities estimated from linear Langmuir model were deviated from the experimental data.

  14. Soil erosion of agricultural land in Western Australia estimated by caesium - 137

    International Nuclear Information System (INIS)

    The caesium-137 technique was used to estimate net soil loss from 10 hill slopes in the agricultural area of Western Australia. The gravel fraction of the soil was found to have approximately 56% of the total 137Cs activity found on the 137Cs appeared not to have uniformly labelled the soils in uncleared areas, possibly due to the redistribution of rainfall in the canopy and above the soil surface, and the water repellence of some soils. A previously established calibration curve was used to calculate net soil losses from the 10 hill slopes. Potato-growing land and slopes below rock outcrops in the Wheat Belt appear to have experienced the most severe erosion since the soils were first labelled with 137Cs in the mid 1950s (19-27 t ha-1 yr-1). Hill slopes below rock outcrops had appreciably less 137Cs than those below lateritic breakaways, indicating the presence of sheet erosion. 15 refs., 2 tabs., 7 figs

  15. A dynamic model of caesium transport in lakes and their catchments

    International Nuclear Information System (INIS)

    A mathematical model has been developed to predict radiocaesium concentrations over time within individual compartments of the lake and its catchment. The lake has been divided into five compartments; catchment, lake water (epilimnion and hypolimnion during stratification), lake sediment and fish. Radiocaesium enters the lake via contaminated rainfall and catchment runoff. A proportion of this radiocaesium absorbs onto suspended solids in the lake. This proportion is represented by a distribution coefficient. Sedimentation of the suspended solids occurs at a rate defined by the areal removal coefficient and results in increased caesium concentrations in the sediment. The ingestion of radiocaesium by either water column or benthic feeding fish is described by transfer functions. The model has been tested against data collected from Esthwaite water and Windermere shortly after the Chernobyl reactor accident from May 1986 to December 1987. The model simulates observed radiocaesium concentrations in Esthwaite lake water and sediment and also in lake water, sediment and fish in Windermere. The model could form the basis of a valuable management tool for the water industry should a major airborne pollution event occur again. (author)

  16. The use of caesium-137 measurements to establish a sediment budget for the Start catchment, Devon

    International Nuclear Information System (INIS)

    Caesium-137 (137Cs) measurements have been used to investigate the delivery of sediment from the hillslopes to a lake which marks the downstream limit of the small agricultural Start basin in Devon, UK. Total 137Cs inventories and 137Cs depth distributions in sediment cores were used to estimate that the eroded sediment stored within the fields and on the flood plain of the main river was equivalent to sediment yields of ca. 21 and 30 t km-2 year-1. Based on published information on sediment accumulation in the lake, the minerogenic sediment yield from the basin was estimated to be ca 29 t km-2 year-1. The erosion rate on the hillslopes in the basin, calculated as the sum of the sediment yield to the lake and the two storage components, is ca. 80 t KM-2 year-1. Of the soil eroded from the slopes more than 60% is stored at intermediate locations and the sediment delivery to the lake is less than 40%. The calculated soil erosion rate for the Start basin is consistent with an estimate of the erosion rate for the basin of the nearby Old Mill Reservoir of ca. 63 t km-2 year-1. (Author)

  17. Mapping of caesium fallout from the Chernobyl accident in the Jotunheimen area

    Energy Technology Data Exchange (ETDEWEB)

    Baranwal, Vikas C.; Ofstad, Frode; Roenning, Jan S.; Watson, Robin J.

    2011-07-01

    As a consequence of the Chernobyl accident, several areas in Norway received radioactive fallout. One of these areas is the eastern part of Jotunheimen in central Norway. Immediately after the accident in 1986, the Geological Survey of Norway (NGU) performed airborne gamma-ray spectroscopy in central Norway. At that time, it was not possible to calculate reliable radionuclide concentrations, and the data were presented as total counts per second. Several man-made radionuclides were present in the initial fallout, but due to short half-lives, most of these have now disintegrated into stable isotopes. 137Cs, with a half-life of 11.000 days ({approx} 30 years) is still present in the environment in significant quantities, leading to high radioactivity levels in meat from reindeer and sheep. To obtain a detailed map of the caesium fallout concentration in Jotunheimen, an airborne gamma-ray spectrometry (AGRS) survey was carried out, focussing on reindeer grazing areas. This project was a cooperation between Reindeer Husbandry Administration, Norwegian Radiation Protection Authority and the Geological Survey of Norway. (auth)

  18. Radiative heat transfer in plasma of pulsed high pressure caesium discharge

    Science.gov (United States)

    Lapshin, V. F.

    2016-01-01

    Two-temperature many component gas dynamic model is used for the analysis of features of radiative heat transfer in pulsed high pressure caesium discharge plasma. It is shown that at a sufficiently high pressure the radial optical thickness of arc column is close to unit (τR (λ) ∼ 1) in most part of spectrum. In this case radiative heat transfer has not local character. In these conditions the photons which are emitted in any point of plasma volume are absorbed in other point remote from an emission point on considerable distance. As a result, the most part of the electric energy put in the discharge mainly near its axis is almost instantly redistributed on all volume of discharge column. In such discharge radial profiles of temperature are smooth. In case of low pressure, when discharge plasma is optically transparent for own radiation in the most part of a spectrum (τR(λ) << 1), the emission of radiation without reabsorption takes place. Radiative heat transfer in plasma has local character and profiles of temperature have considerable gradient.

  19. Caesium and tungsten behaviour in the filamented arc driven Kamaboko-III negative ion source

    International Nuclear Information System (INIS)

    The ITER neutral beam injection is based on the acceleration and neutralization of negative deuterium ions. The target performance for the ITER beam source is to accelerate to 1 MeV a 40 A D- beam, with a current density of 200 A m-2, with pulse lengths of ≥1000 s. It was found that in long pulse operation the negative ion yield from the filamented Kamaboko III ion source (a model of ITER ion source) degrades in comparison with short pulse operation, <5 s. This could be linked to the behaviour of caesium (Cs), which is added to the source to increase its negative ion yield and tungsten (W) evaporated from filaments. Cs and W are co-adsorbed on the source walls and the plasma grid and the composition of this coating can vary during long pulse operation. The possible consequences of this changing surface on the negative ion production will be discussed. Tungsten filaments have a limited lifetime in the ion source and changing filaments and refilling of the Cs oven are the only scheduled maintenance events for the ITER injectors. These are complicated operations as the ITER injectors will be highly activated and all maintenance has to be carried out remotely. Therefore, increasing the filament lifetime and decreasing the Cs consumption are highly desirable. This paper presents results of relative measurements (including spectroscopic and chemical) of the W content of the Kamaboko-III source and reports relevant calculations on Cs consumption and W evaporation

  20. Enhancement of the work function of indium tin oxide by surface modification using caesium fluoride

    International Nuclear Information System (INIS)

    The work function of indium tin oxide (ITO) was modified using caesium fluoride (CsF). Various concentrations of CsF was spin-coated on top of ITO and baked while the residual CsF was washed away with DI water. The work function of all the ITO samples was measured using ultraviolet photoelectron spectroscopy and it was found that the work function of ITO reaches as high as 5.75 eV. The work function rapidly increases with small concentrations of CsF solution and then decreases for higher concentrations. Using atomic force microscopy and x-ray photoelectron spectroscopy, the cause was determined to be the change in surface roughness and the oxygen concentration, with the former having a much greater influence on the work function than the latter. The current density of ITO/poly(vinylcarbazole)/Al hole-only devices using the modified ITO increases by more than seven orders of magnitude compared with the control device. (paper)

  1. Effect of soil potassium and calcium on caesium and strontium uptake by plant roots

    International Nuclear Information System (INIS)

    Caesium-134 and 85Sr root uptake was studied in lettuce plants growing in two contaminated soils with contrasting properties: sandy-loam versus sandy texture, each with 1.5 and 0.1 cmol kg-1 of K exchangeable forms, and 9.1 and 1.6 cmol/ kg-1 of Ca exchangeable forms, respectively. The soil was contaminated by aerosols representative of a nuclear power plant accidental release at far-field conditions. The percentage of the total deposition absorbed by mature plants was always very low: 0.04% and 0.28% for 134Cs and, 1.33% and 5.17% for 85Sr in sandy-loam and sandy soil, respectively. In plants, 134Cs and 85Sr radionuclide activity concentrations decreased over time. The transfer factors were higher in the sandy soil. Greater K selectivity than 134Cs was always observed, although the selectivity of K was higher in the sandy soil which had a lower K concentration. In the sandy-loam soil which had a higher Ca concentration, selectivity of 85Sr was higher than that of Ca. These results suggest that radionuclide uptake by roots depended on the availability in the soil of the radionuclides and root uptake selectivity, which were both related to the nutrient concentration in the soil solution. (Author)

  2. Strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions

    International Nuclear Information System (INIS)

    This work is devoted to the quantification and the identification of the predominant processes involved in strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions. The transport and fate of radionuclides in the subsurface is affected by various physical and chemical processes including advective and diffusive transport as well as chemical and biological transformations. Laboratory experiments and the use of a multiple tracer approach allow to isolate the contributions of each elementary process and to control the physico-chemical conditions in the system. To be more representative of the field conditions, we decided to perform column miscible displacement experiments. We perform batch and flow-through reactor experiments to characterize the radionuclides sorption mechanisms. Miscible displacement experiments within homogeneous columns and modeling allow to characterize the hydrodynamic properties of the soil and to describe the radionuclides behaviour under dynamic conditions at different water contents. We show that the water content of porous media affect the transport behaviour of inert and strongly sorbing radionuclides. Our results demonstrate that a parametrized transport model that was calibrated under completely saturated conditions was not able to describe the advective-dispersive transport of reactive solutes under unsaturated steady state conditions. Under our experimental conditions, there is no effect of a decrease of the mean water content on the sorption model parameters, but the transport parameters are modified. We established for the studied soil the relation between hydrodynamic dispersion and water content and the relation between pore water velocity and water content. (author)

  3. A preference for migration

    OpenAIRE

    Stark, Oded

    2007-01-01

    At least to some extent migration behavior is the outcome of a preference for migration. The pattern of migration as an outcome of a preference for migration depends on two key factors: imitation technology and migration feasibility. We show that these factors jointly determine the outcome of a preference for migration and we provide examples that illustrate how the prevalence and transmission of a migration-forming preference yield distinct migration patterns. In particular, the imitation of...

  4. The kinetics of caesium absorption by roots of winter wheat and the possible consequences for the derivation of soil-to-plant transfer factors for radiocaesium

    International Nuclear Information System (INIS)

    Caesium (Cs) uptake in roots of winter wheat followed a dual pattern similar to that established for potassium uptake in barley roots. This suggests the operation of two discrete uptake systems for Cs. The 'System 1' (low concentration) uptake mechanism for caesium, however, can be resolved into two hyperbolic components which both obey Michaelis-Menten kinetics. The Michaelis-Menten equation was used to derive a function which describes the variation in solution-to-root transfer factor for any element for which the appropriate root uptake constants (Km and Vmax) can be determined. This function successfully described available data for root uptake of caesium and potassium, predicting that the solution-to-root transfer factor decreases in relation to an increase in the substrate concentration of each respective element. At substrate concentrations equivalent to carrier-free radiocaesium concentrations, however, the solution-to-root transfer factor predicted by the function and by empirical data suggests that the relationship between root uptake and solution concentration of caesium is linear. These findings are discussed in relation to the comparative physiology of caesium and potassium uptake by plant roots and with respect to radioecological studies. (author)

  5. Higher order Godunov schemes for isothermal hydrodynamics

    Science.gov (United States)

    Balsara, Dinshaw S.

    1994-01-01

    In this paper we construct higher order Godunov schemes for isothermal flow. Isothermal hydrodynamics serves as a good representation for several systems of astrophysical interest. The schemes designed here have second-order accuracy in space and time and some are third-order accurate for advection. Moreover, several ingredients of these schemes are essential components of even higher order. The methods designed here have excellent ability to represent smooth flow yet capture shocks with high resolution. Several test problems are presented. The algorithms presented here are compared with other algorithms having a comparable formal order of accuracy.

  6. Modeling of the sorptive behavior of a clay material used as reactive barrier for cesium migration in Huelva (Spain)

    International Nuclear Information System (INIS)

    different homo-ionic forms (Na, Ca, K) and sorption of caesium evaluated at different ionic strengths. Sorption data in the homo-ionic system were modeled considering the ionic exchange approach. Figure 1 shows an example of the procedure carried out. The Figure shows the sorption isotherms obtained on the Na-exchanged RC clay dispersed in NaCl at two different concentration 0.28 and 0.13 mol/L. The adsorption isotherm showed a non linear behavior, most probably dominated by the presence of illite, thus was modeled considering the existence of three sorption sites. The result of the modeling is superimposed to the experimental points. With the basic selectivity coefficient determined in this way the blind prediction of the sorption behavior of the material under different in-situ conditions was carried out along with a sensitivity study on the main parameters of interest (content of clay, site density, BET, presence of competing ions,...). The application of this modeling approach was shown to be quite successful in reproducing the distribution coefficient previously measured under different experimental conditions; furthermore it allowed estimating the actual experimental variability and range of uncertainty of Kd values determination

  7. In-vivo estimates for the uptake of caesium-137 by cattle grazing contaminated pasture around the Esk and Irt estuaries, Cumbria, U.K

    International Nuclear Information System (INIS)

    Sea water contaminated with diluted radioactive effluent from the Windscale nuclear complex in Cumbria periodically floods low-lying grazing pasture around the estuaries of the rivers Esk, Irt and Mite near Ravenglass. During 1979, an experiment was carried out to measure the transfer of caesium-137 from grass to muscle in cows grazing these pastures. Grass samples were taken and in vivo external gamma-ray measurements were made on cattle. A very low transfer coefficient was found, less than 9 x 10-4 days kg-1 with a best estimate of 4 x 10-4 days kg-1, compared with a more usual value of around 3 x 10-2 days kg-1. The low transfer seems to occur because the bulk of the caesium-137 on the grass is bound to resuspended estuarine surface sediment deposited during flooding. In this form, the caesium-137 is only poorly adsorbed across the gut of the grazing cattle. (orig.)

  8. In-vivo estimates for the uptake of caesium-137 by cattle grazing contaminated pasture around the ESK and IRT estuaries, Cumbria, U.K.

    Science.gov (United States)

    Sumerling, T J

    1981-12-01

    Sea water contaminated with diluted radioactive effluent from the Windscale nuclear complex in Cumbria periodically floods low-lying grazing pasture around the estuaries of the rivers Esk, Irt and Mite near Ravenglass. During 1979, an experiment was carried out to measure the transfer of caesium-137 from grass to muscle in cows grazing these pastures. Grass samples were taken in a vivo external gamma-ray measurements were made on cattle. A very low transfer coefficient was found, less than 9 X 10-4 days kg-1 with a best estimate of 4 X 10-4 days kg-1, compared with a more usual value of around 3 X 10-2 days kg-1. The low transfer seems to occur because the bulk of the caesium-137 on the grass is bound to resuspended estuarine surface sediment deposited during flooding. In this form, the caesium-137 is only poorly absorbed across the gut of the grazing cattle. PMID:7336201

  9. The influence of caesium-137 distribution in Poland's north-eastern ecosystem on effective dose 10 years after the Chernobyl disaster

    International Nuclear Information System (INIS)

    A comparison is presented of particular methods of exposure in the first year after the Chernobyl disaster and ten years later. This comparison shows that the population exposure due to the presence of radiocaesium in the environment results from the presence of caesium contained in the soil, which provides 68% of the dose (as compared to 32% in 1987) while the influence of diet has been reduced to 32% (from 68%). The exposure from caesium-137 contained in the air has dropped from 14% to 0. The effective dose from caesium has been 50 times smaller than that from environmental sources of the natural radiation estimated for the region under study to be 1.61 mSv.y-1. (author)

  10. Isothermal Gravitational Segregation: Algorithms and Specifications

    DEFF Research Database (Denmark)

    Halldórsson, Snorri; Stenby, Erling Halfdan

    2000-01-01

    New algorithms for calculating the isothermal equilibrium state of reservoir fluids under the influence of gravity are presented. Two types of specifications are considered: the specification of pressure and composition at a reference depth; and the specification of the total overall content of t...

  11. Performance Characteristics of an Isothermal Freeze Valve

    Energy Technology Data Exchange (ETDEWEB)

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  12. Isothermal Titration Calorimetry in the Student Laboratory

    Science.gov (United States)

    Wadso, Lars; Li, Yujing; Li, Xi

    2011-01-01

    Isothermal titration calorimetry (ITC) is the measurement of the heat produced by the stepwise addition of one substance to another. It is a common experimental technique, for example, in pharmaceutical science, to measure equilibrium constants and reaction enthalpies. We describe a stirring device and an injection pump that can be used with a…

  13. Measurements of Caesium-137 in Finnish Lapps in 1962-1964 by a Mobile Whole-Body Counter

    International Nuclear Information System (INIS)

    The construction, calibration and use in-field investigations of a mobile whole-body counter of the type developed by K. Lidén et al, in Sweden are described. The lead shield of the present system (2 t) is located)in-the middle of a covered heavy truck. The subject is surrounded by a 4-cm thick lead coffin, the Nal(Tl) crystal (5 an-diam. x 3 in) being protected from the other directions than the coffin by 8 cm of lead. The instrumentation consists of a 512-channel analyser, printer, x, y-recorder, and stabilizer, which are kept in shock- and dust-proof boxes during transport. The truck is provided with a thermostated heating system and contains two dressing cubicles. The system was calibrated for caesium-137 by two methods: (1) By administering per os a precisely known amount (200 to 300 nc) caesium-137 to several subjects and determining the counting efficiency after 3 to 6 d. The excreted portion of caesium-137 was determined by collecting and analysing the faeces and urine. (2) By counting a plastic phantom filled with 70.kg of a solution containing 1552 nc caesium-137. The first method gave a 4,6% higher efficiency than the second. The efficiency obtained by the first method was adopted as, the true calibration. This was also checked by three inter-calibration measurements with two other whole-body counting laboratories. The agreement was good (within 1 to 4%). For potassium a preliminary calibration was made by the use of the phantom. The efficiency is 2.51 cpm/nc caesium-137 (0.60- 0.72 MeV, 20 channels), and 0.145 cpm/g K (1.38- 1.55 MeV, 30 channels). When the truck is parked on rock, the corresponding background counts with a 70 kg sugar phantom-are 77 cpm and, 58 cpm, respectively. On sandy soil the background is about half of that on rock. With this mobile counter three field investigations were carried out in Finnish Lapland. In May 1962 218 Lapps statistically representative groups from the three Finnish Lapp countries, Inari, Karesuanto and Utsjoki

  14. Radioactive caesium in Boreal forest landscapes - Dynamics and transport in food webs. Summary of research 1986-1996

    Energy Technology Data Exchange (ETDEWEB)

    Bergman, R.; Nylen, T.; Palo, T

    1998-12-01

    The need for - but also the paucity of - radioecological knowledge concerning the boreal forest became particularly apparent after the nuclear power plant accident in Chernobyl in April 1986. As a consequence several new projects were initiated in the Nordic countries with particular focus on the behaviour of radioactivecaesium in terrestrial and aquatic systems characteristic for the Fenno-Scandinavian landscapes. Among these new projects a multi-disciplinary co-operation in Umeaa between scientists at the Swedish University of Agricultural Sciences, and the Defence Research Establishment emerged. Initially this joint work focused mainly on descriptions of the dynamic changes of the content of radioactive caesium in soil-plant and animal communities in the county of Vaesterbotten. Most of the studies have been performed at the Vindeln experimental forest, 60 km NW of Umeaa. Plants of key interest were: bilberry (Vaccinium myrtillus), birch (Betula spp.), and pine (Pinus sylvestris), and among the animals: the moose (Alces alces) and a small rodent, the forest vole (Clethrionomus glareolus). Gradually over the past ten years the research has entered the stage where the specific causes of the caesium behaviour have been addressed - partly by the help of models developed for simulating forest ecosystems, partly by complementary field experiments. This paper reviews our main findings on this theme concerning the behaviour of radioactive caesium in boreal landscapes and significant pathways to man, as has become apparent from the radioecological co-operation dating from about ten years back. A list of the publications arising from these studies since 1986 is also presented in this report.

  15. Coronal Loops: Evolving Beyond the Isothermal Approximation

    Science.gov (United States)

    Schmelz, J. T.; Cirtain, J. W.; Allen, J. D.

    2002-05-01

    Are coronal loops isothermal? A controversy over this question has arisen recently because different investigators using different techniques have obtained very different answers. Analysis of SOHO-EIT and TRACE data using narrowband filter ratios to obtain temperature maps has produced several key publications that suggest that coronal loops may be isothermal. We have constructed a multi-thermal distribution for several pixels along a relatively isolated coronal loop on the southwest limb of the solar disk using spectral line data from SOHO-CDS taken on 1998 Apr 20. These distributions are clearly inconsistent with isothermal plasma along either the line of sight or the length of the loop, and suggested rather that the temperature increases from the footpoints to the loop top. We speculated originally that these differences could be attributed to pixel size -- CDS pixels are larger, and more `contaminating' material would be expected along the line of sight. To test this idea, we used CDS iron line ratios from our data set to mimic the isothermal results from the narrowband filter instruments. These ratios indicated that the temperature gradient along the loop was flat, despite the fact that a more complete analysis of the same data showed this result to be false! The CDS pixel size was not the cause of the discrepancy; rather, the problem lies with the isothermal approximation used in EIT and TRACE analysis. These results should serve as a strong warning to anyone using this simplistic method to obtain temperature. This warning is echoed on the EIT web page: ``Danger! Enter at your own risk!'' In other words, values for temperature may be found, but they may have nothing to do with physical reality. Solar physics research at the University of Memphis is supported by NASA grant NAG5-9783. This research was funded in part by the NASA/TRACE MODA grant for Montana State University.

  16. Caesium removal from fuel pond water using a composite ion exchanger containing nickel hexacyanoferrate

    International Nuclear Information System (INIS)

    Spent fuel elements from the Bohunice A1 reactor were stored in a pond. To limit corrosion of the cladding, they were held within thimbles which contained a corrosion inhibiting solution of potassium chromate (Chrompik). This proved to be not effective enough, fuel pins did fail, releasing significant amounts of radioactive caesium and also, due to hydrogen gas pressurisation, significant amounts of contaminated Chrompik were released into the pond together with approximately 100 TBq of Cs-137. This paper presents the work undertaken to remove this Cs-137 as part of the first phase of decommissioning the pond. The design is based on a skid mounted unit, comprising a shielded mechanical filter unit and a shielded ion exchange (IX) column unit, with interconnecting pipework and valves. The IX column is housed within a lead shielded overpack and connections to it are made by self-sealing quick release couplings. The IX column is of upward flow design and filled with a composite ion exchanger containing Nickel Hexacyanoferrate (II). The IX column packages may be stored within their own shielding once spent. Two operational runs have been completed, removing 25 TBq of Cs137 in each run. With a fresh column, the Decontamination Factor (DF) for Cs-137 uptake was initially over 5000. The DF then fell slowly over the first 1000 bed volumes to 3500, where it remained for most of the run. The run was terminated when calculations indicated that the column packing had absorbed the specified maximum loading of 25 TBq of Cs137. At this point the DF was 1500

  17. Promotion of radiation peroxidation in models of lipid membranes by caesium and rubidium counter-ions: micellar linolenic acids

    International Nuclear Information System (INIS)

    Caesium and rubidium counter-ions increase peroxidation in irradiated micelles of linoleic (18 : 2) and linolenic (18 :3) acids. The effect was specific to Cs+ and Rb+ in the alkali metal series. The effect was independent of the salts used (Cl-, NO3-, Cl04-) and, therefore, independent of the chaotropic nature, and reactivity with hydroxyl radicals of Cl-, NO3- and ClO4-. The promotion of peroxidation by Cs+ and Rb+ is interpreted in terms of their effect on fatty acid micelle structure. The dependence of radiation peroxidation on lipid structure in the micelles may be significant for studies of peroxidation in highly structured cell membranes. (author)

  18. Results of several years experiments on the absorption of radioactive strontium and caesium by cultivated plants (1962)

    International Nuclear Information System (INIS)

    This report follows on to the report number CEA 1860 and uses results obtained in 1960 to give more precise details concerning the data presented in the preceding report. First results obtained on the vine are given. The Sr absorption coefficient has varied very little from one year to the next and that of caesium has slightly diminished. The values obtained suggest that the concentrations of 90Sr and 137Cs in irrigation water should not exceed 1/5 of the maximum permissible concentration in drinking water. (authors)

  19. Poly[μ-aqua-μ5-[2-(2,3,6-tri­chloro­phenyl)acetato]-caesium

    OpenAIRE

    Graham Smith

    2013-01-01

    In the structure of the title complex, [Cs(C8H4Cl3O2)(H2O)]n, the caesium salt of the commercial herbicide fenac [(2,3,6-trichlorophenyl)acetic acid], the irregular eight-coordination about Cs+ comprises a bidentate O:Cl-chelate interaction involving a carboxylate-O atom and an ortho-related ring-substituted Cl atom, which is also bridging, a triple-bridging carboxylate-O atom and a bridging water molecule. A two-dimensional polymer is generated, lying parallel to (100), within which there ar...

  20. EU Migration Policy

    OpenAIRE

    Kleinschmidt, Harald

    2004-01-01

    I shall confine myself in this paper to international migration as migration across international borders.I do so despite the fact that,still today,international migration accounts only for a small share of migration at large.Likewise,I shall deal widh voluntary migration and shall thus exclude,deportation ...

  1. Studies of nuclear-waste migration in geologic media. Annual report, October 1977-September 1978

    International Nuclear Information System (INIS)

    The first phenomenon studied is incomplete water-nuclide-rock reaction because of slow reaction kinetics. A kinetic factor derived from the experimental results for strontium migration through glauconite (a hydrous silicate) was expressed in terms of the linear flow rate of solution and can be used to predict migration due to solution flow at rates of 0 to about 12 cm/min (60 km/y). Continuous-flow infiltration experiments with americium in fissures gave results that are predicted by a migration model that includes kinetic factors measured in experiments with static fluids. The results suggest that kinetic factors are as important as equilibrium adsorption parameters in predicting nuclide migration. The second phenomenon studied was the amount of adsorbed nuclide not being proportional to the nuclide concentration in solution (nonlinear adsorption isotherm). For cesium adsorption on limestone, a nonlinear isotherm was found to occur in the range of initial cesium concentrations from about 10-3 to 10-9M. This adsorption property was confirmed by results of column-infiltration experiments in which cesium migration through oolitic limestone was found to be sensitive to the amount of cesium in solution. The existence of a nonlinear isotherm precludes the use of a single partition value (K/sub D/) to describe cesium migration in limestone at cesium concentrations above about 10-9M. Therefore, the effects of nonlinear isotherms are germane to nuclide migration. 24 figures, 6 tables

  2. Isothermal calorimetry on enzymatic biodiesel production

    DEFF Research Database (Denmark)

    Fjerbæk, Lene

    2008-01-01

    information about effects taking place when using lipases immobilized on an inert carrier for transesterification of a triglyceride and an alcohol as for biodiesel production. The biodiesel is produced by rapeseed oil and methanol as well as ethanol and a commercial biocatalyst Novozym 435 from Novozymes...... containing a Candida Antarctica B lipase immobilized on an acrylic resin. The reaction investigated is characterized by immiscible liquids (oil, methanol, glycerol and biodiesel) and enzymes imm. on an inert carrier during reaction, which allows several effects to take place that during normal reaction...... conditions can not be elucidated. These effects have been observed with isothermal calorimetry bringing forth new information about the reaction of enzymes catalyzing transesterification. Enzymatic biodiesel production has until now not been investigated with isothermal microcalorimetry, but the results...

  3. Concerning isothermal self-similar blast waves

    International Nuclear Information System (INIS)

    The two-dimensional self-similar flow behind a blast wave from a line explosion in a medium whose density varies with distance as rsup(-ω) is investigated with the assumption that the flow is isothermal. If ω ω > 0, no critical points exist and a continuous solution passing through both the origin and the shock is shown to exist. If 16/9 = 2 no physically acceptable solution exists since the mass behind the shock is infinite. The dependence of the solutions which have zero flow velocity at the origin on the parameter ω is analytic for ω > 0 so that interpolation between neighboring values of ω is permitted. The stability of these isothermal blast waves is investigated to two-dimensional but non-self-similar perturbations. (Auth.)

  4. Isothermal blast wave model of supernova remnants

    International Nuclear Information System (INIS)

    The validity of the ''adiabatic'' assumption in supernova remnant calculations is examined, and the alternative extreme of an isothermal blast wave is explored. It is concluded that, because of thermal conductivity, the large temperature gradients predicted by the adiabatic model probably are not maintained in nature. Self-similar solutions to the hydrodynamic equations for an isothermal blast wave have been found and studied. These solutions are then used to determine the relationship between X-ray observations and inferred parameters of supernova remnants. A comparison of the present results with those for the adiabatic model indicates differences which are less than present observational uncertainties. It is concluded that most parameters of supernova remnants inferred from X-ray measurements are relatively insensitive to the specifics of the blast wave model

  5. Isothermal blast wave model of supernova remnants

    Science.gov (United States)

    Solinger, A.; Buff, J.; Rappaport, S.

    1975-01-01

    The validity of the 'adiabatic' assumption in supernova-remnant calculations is examined, and the alternative extreme of an isothermal blast wave is explored. It is concluded that, because of thermal conductivity, the large temperature gradients predicted by the adiabatic model probably are not maintained in nature. Self-similar solutions to the hydrodynamic equations for an isothermal blast wave have been found and studied. These solutions are then used to determine the relationship between X-ray observations and inferred parameters of supernova remnants. A comparison of the present results with those for the adiabatic model indicates differences which are less than present observational uncertainties. It is concluded that most parameters of supernova remnants inferred from X-ray measurements are relatively insensitive to the specifics of the blast-wave model.

  6. ISOTHERMAL PYROLYSIS OF KRAFT PULP MILL SLUDGE

    OpenAIRE

    Syamsudin Syamsudin; Herri Susanto; Subagjo Subagjo

    2014-01-01

    Kraft pulp mill sludge cake composed of rejected wood fibers and activated sludge microorganisms. With a heating value about 14 MJ/kg (dried basis), this type of biomass had a potential as an alternative energy source. Unfortunately, it had an ash content of 27.6% and a moisture content of 80%. For reducing moisture content with minimum energy consumption, a combination of mechanical dewatering and thermal drying was studied previously. Meanwhile, experiments on isothermal pyrolysis had been ...

  7. Temperature effects for isothermal polymer crystallization kinetics

    OpenAIRE

    Yang, Jiao; McCoy, Benjamin J; Madras, Giridhar

    2005-01-01

    We adopt the cluster size distribution model to investigate the effect of temperature on homogeneous nucleation and crystal growth for isothermal polymer crystallization. The model includes the temperature effects of interfacial energy, nucleation rate, growth and dissociation rate coefficients, and equilibrium solubility. The time dependencies of polymer concentration, number and size of crystals, and crystallinity (in Avrami plots) are presented for different temperatures. The denucleation ...

  8. Quasistatic isothermal evolution of shape memory alloys

    OpenAIRE

    Frigeri, Sergio; Krejčí, Pavel; Stefanelli, Ulisse

    2011-01-01

    This paper focuses on a three-dimensional phenomenological model for the isothermal evolution of a polycrystalline shape memory alloy. The model, originally proposed by Auricchio, Taylor, and Lubliner in 1997, is thermodynamically consistent and reproduces the crucial martensitic reorientation effect as well as the tension-compression asymmetric behavior of the material. We prove the existence of a weak solution of the corresponding quasistatic evolution problem by passing to the limit within...

  9. Analysis of Cooperativity by Isothermal Titration Calorimetry

    OpenAIRE

    Alan Brown

    2009-01-01

    Cooperative binding pervades Nature. This review discusses the use of isothermal titration calorimetry (ITC) in the identification and characterisation of cooperativity in biological interactions. ITC has broad scope in the analysis of cooperativity as it determines binding stiochiometries, affinities and thermodynamic parameters, including enthalpy and entropy in a single experiment. Examples from the literature are used to demonstrate the applicability of ITC in the characterisation of coop...

  10. The Use of Caesium-137 Measurements for Assessing Soil Erosion and Sedimentation in the Riva Basin (Istanbul, NW Turkey)

    International Nuclear Information System (INIS)

    The paper summarizes the findings of an assessment of soil redistribution in the Riva basin, upstream of the Omerli reservoir, based on use of the fallout radionuclide Caesium-137. This reservoir is located at the eastern side of Istanbul, Turkey, and is the main provider for water to Istanbul. In the Riva basin, soil erosion and associated sediment deposition and potential mass movements are natural landscape forming processes. However, these processes are being accelerated by human intervention, creating a serious threat for sustainable intensification of the agricultural production, watershed management and the conservation of the local natural resources. To determine soil redistribution rates and patterns using the fallout radionuclide approach, samples were collected from an uncultivated flat reference sites and the cultivated sloping farmland (two transects). According to the results of gamma spectroscopy measurements of Caesium-137 and the outputs from the proportional model and simplified mass balance model for both transects, erosion rates varied between -2.4 t ha-1 a-1 and -36.0 t ha-1 a-1 and deposition rates between +1.7 t ha-1 a-1 and +10.5 t ha-1 a-1. (author)

  11. Neuronal Migration Disorders

    Science.gov (United States)

    ... Enhancing Diversity Find People About NINDS NINDS Neuronal Migration Disorders Information Page Table of Contents (click to ... being done? Clinical Trials Organizations What are Neuronal Migration Disorders? Neuronal migration disorders (NMDs) are a group ...

  12. Migration of birds

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This report covers the migration of birds. Topics covered include why birds migrate, when birds migrate, speed, altitude, courses, distance, major flyways and...

  13. Research on Protocol Migration

    Institute of Scientific and Technical Information of China (English)

    汪芸; 顾冠群; 等

    1996-01-01

    This paper elaborates the concept and model of protocol migration in network interconnection.Migration strategies and principles are discussed and several cases are studied in detail which show the basic procedure and techniques used in protocol migration.

  14. A Short Note on Non-isothermal Diffusion Models

    Directory of Open Access Journals (Sweden)

    T. Ficker

    2003-01-01

    Full Text Available Asymptotic behaviour of the DIAL and DRAL non-isothermal models, derived previously for the diffusion of water vapour through a porous building structure, is studied under the assumption that the initially non-isothermal structure becomes purely isothermal.

  15. Isothermal martensite formation at sub-zero temperatures

    DEFF Research Database (Denmark)

    Stojko, Allan; Hansen, Mikkel Fougt; Slycke, Jan;

    2012-01-01

    temperatures in the range of 80-233 K. The kinetics of isothermal martensite formation depends strongly on the temperature and can be described by Johnson-Mehl-Avrami-Kolmogorov kinetics. Isothermal experiments with dilatometry indicated the occurrence of a volume increase on isothermal holding, consistent...

  16. Isothermal martensite formation at sub-zero temperatures

    DEFF Research Database (Denmark)

    Stojko, Allan; Hansen, Mikkel Fougt; Slycke, Jan;

    2011-01-01

    temperatures in the range of 80-233 K. The kinetics of isothermal martensite formation depends strongly on the temperature and can be described by Johnson-Mehl-Avrami-Kolmogorov kinetics. Isothermal experiments with dilatometry indicated the occurrence of a volume increase on isothermal holding, consistent...

  17. An isothermal equation of state for solids

    International Nuclear Information System (INIS)

    An isothermal equation of state (EOS) for solids, recently suggested by the authors in the realistic form, V/V0=f(P), with relative volume as the dependent and the pressure as the independent variable, was shown to have an advantage for some close-packed materials in that it allows B'∞=(∂Bs/∂P)s(P→∞) to be fitted, and this is where the usual standard equations fail. In the present study, our EOS is applied to a number of inorganic as well as organic solids, including alloys, glasses, rubbers and plastics; varying widely in their bonding and structural characteristics, as well as in their bulk modulus values. A very good agreement is observed between the data and fits. The results obtained are compared with those from two well-known equations, expressible in the realistic form, proposed by Murnaghan and Luban. Further, the results are also compared with those from the widely used two- and three-parameter EOSs, expressible in the unrealistic form only, P=f(V/V0), proposed by Birch--and also with those from the EOS model of Keane in which B'∞ is explicitly expressed as an equation of state parameter. The results obtained from our model compare well to these EOSs. Our EOS, in general, yields the smallest mean-squared deviations between data and fits. The values of B'∞calculated from our EOS are compared with those from Keane's model. Further, we have studied the variation of B'∞with temperature using the experimental isotherms of Mo and W at 10 different temperatures ranging from 100 to 1000 K, and observed that the values of B'∞ yielded by our model and that of Keane vary, as expected, within a narrow range. Furthermore, our EOS is applied to study the stability of the fit parameters with variation in the pressure ranges with reference to the isothermal compression data on Mo and W--and also to study the variation of isothermal bulk modulus with pressure, with reference to the ultrasonic data on NaCl and noted a very good agreement with experiment

  18. Sediment Budgets and Source Determinations Using Fallout Caesium-137 in a Semiarid Rangeland Watershed, Arizona, USA

    International Nuclear Information System (INIS)

    Analysis of soil redistribution patterns and sediment sources in semiarid and arid watersheds provides information for understanding watershed sediment budgets and for implementing management practices to improve rangeland conditions and reduce sediment loads in streams. The purpose of this research was to develop sediment budgets and to identify potential sediment sources using 137Caesium (137Cs) and other soil properties in a series of small semiarid subwatersheds on the USDA ARS Walnut Gulch Experimental Watershed near Tombstone, Arizona, USA. Soils were sampled in a grid pattern on two small subwatersheds and along transects associated with soils and geomorphology on six larger subwatersheds. Soil samples were analyzed for 137Cs and selected physical and chemical properties (i.e. bulk density, rocks, particle size, soil organic carbon). Suspended sediment samples collected at flume sites on the Walnut Gulch Experimental Watershed were also analyzed for the same properties. Sediment budgets measured using 137Cs inventories for a small shrub and a small grass subwatersheds found eroding areas in these watersheds were losing 5.6 and 3.2 t ha-1 a-1, respectively; however, a sediment budget for each of the small subwatersheds, including depositional areas, found net soil loss to be 4.3 t ha-1 a-1 from the shrub watershed and near zero t ha-1 a-1 from the grass subwatershed. The suspended sediments collected at the flumes of the larger subwatersheds were enriched in silt, clay, and 40K, but not for 137Cs. Using multivariate mixing models to determine sediment source indicated that the shrub dominated subwatersheds were contributing most of the suspended sediments measured at the outlet flume of the Walnut Gulch Experimental Watershed. Both methodologies (sediment budgets and sediment source analyses) indicate that shrub dominated systems provide more suspended sediments to the stream systems. These studies also suggest that sediment yields measured at the outlet of a

  19. 137 Caesium distribution in the eastern Mediterranean Sea. Recent changes and future trends

    International Nuclear Information System (INIS)

    A series of sampling campaigns were carried out in the eastern Mediterranean in the period 1995-1997, to examine the relationship between the distribution of 137Cs in the water column and water mass circulation. 137Cs concentration in the surface water ranges between 3.3 and 4.0 mBq/l all over the area, indicating that the input due to the Chernobyl accident has been transferred to deep water layers by convection processes. In fact, in the vertical profiles, relative maxima are observed in the intermediate (4 mBq/l) and deep waters (∼2.5 mBq/l) formed after the Chernobyl accident. A clear Chernobyl signal also traces the new deep waters formed in the Aegean Sea that, exiting from the Cretan Arc Straits, since 1991 are spreading in the bottom layer of the eastern Mediterranean. The changes in 137Cs vertical profiles related to the new thermohaline circulation of the intermediate and deep waters of the eastern Mediterranean are being monitored at a deep station in the western Ionian Sea. The 1997 profile shows a decrease in 137Cs concentration both in the Levantine intermediate water and in the eastern Mediterranean deep water with respect to 1996. The decrease in Levantine intermediate water is likely due to seasonal/interannual variability, while the changes in the deep layer are related to the spreading westward into the Ionian of the new Aegean dense water. Along the path towards the western Mediterranean, 137Cs content in the Levantine intermediate water decreases from ∼4 mBq/l in the W-Ionian Sea to ∼2 mBq/l at the western sill of the Sicily Straits, due to mixing with underlying water, with lower caesium content, near the Malta Sill. Time-series measurements at the western sill of the Sicily Straits show that, while 137Cs concentration in the surface water entering the eastern Mediterranean remained constant (∼3.5 mBq/l) in the period 1993-1997, its level in the Levantine intermediate water leaving the basin decreased from 3.5 to 2.0 mBq/l

  20. {sup 137} Caesium distribution in the eastern Mediterranean Sea. Recent changes and future trends

    Energy Technology Data Exchange (ETDEWEB)

    Papucci, C.; Delfanti, R. [ENEA, Marine Environment Research Centre, P.O. Box 316, 19100 La Spezia (Italy)

    1999-09-30

    A series of sampling campaigns were carried out in the eastern Mediterranean in the period 1995-1997, to examine the relationship between the distribution of 137Cs in the water column and water mass circulation. 137Cs concentration in the surface water ranges between 3.3 and 4.0 mBq/l all over the area, indicating that the input due to the Chernobyl accident has been transferred to deep water layers by convection processes. In fact, in the vertical profiles, relative maxima are observed in the intermediate (4 mBq/l) and deep waters ({approx}2.5 mBq/l) formed after the Chernobyl accident. A clear Chernobyl signal also traces the new deep waters formed in the Aegean Sea that, exiting from the Cretan Arc Straits, since 1991 are spreading in the bottom layer of the eastern Mediterranean. The changes in 137Cs vertical profiles related to the new thermohaline circulation of the intermediate and deep waters of the eastern Mediterranean are being monitored at a deep station in the western Ionian Sea. The 1997 profile shows a decrease in 137Cs concentration both in the Levantine intermediate water and in the eastern Mediterranean deep water with respect to 1996. The decrease in Levantine intermediate water is likely due to seasonal/interannual variability, while the changes in the deep layer are related to the spreading westward into the Ionian of the new Aegean dense water. Along the path towards the western Mediterranean, 137Cs content in the Levantine intermediate water decreases from {approx}4 mBq/l in the W-Ionian Sea to {approx}2 mBq/l at the western sill of the Sicily Straits, due to mixing with underlying water, with lower caesium content, near the Malta Sill. Time-series measurements at the western sill of the Sicily Straits show that, while 137Cs concentration in the surface water entering the eastern Mediterranean remained constant ({approx}3.5 mBq/l) in the period 1993-1997, its level in the Levantine intermediate water leaving the basin decreased from 3.5 to 2

  1. Combined Use of Caesium-137 Methodology and Conventional Erosion Measurements in the Mistelbach Watershed (Austria)

    International Nuclear Information System (INIS)

    Over the past thirty years, many studies identified water erosion worldwide as one of the major causes of soil degradation on arable land. However, in order to develop appropriate soil conservation strategies more quantitative long term assessments of the soil erosion process are still needed. Therefore, in the present study, the magnitude of erosion and sedimentation was quantified using Fallout RadioNuclides (FRN) in combination with conventional runoff plots measurements in a small agricultural watershed under conventional and conservation cropping practices at Mistelbach located in Austria. A preliminary test of the use of the FRN Caesium-137 (137Cs) was successfully implemented in the Mistelbach watershed. A valid reference site - a small forest within the watershed - was identified and characterized (texture and physicochemical parameters). In this undisturbed area, a classical exponential depth distribution of 137Cs activity was found with 90% of the 137Cs in the first 15 cm; no 137Cs was detected below 20 cm. Seventy six (76) samples were collected on integrated grids basis. The reference value was 1954±91 Bq m-2 (mean ± 95% confidence interval) with a coefficient of variation of 20.4%. Two one meter soil profiles were also collected in the sedimentation area and analysed using the 137Cs method combined with the conversion model Mass Balance Model 2 (MBM 2). Using the 137Cs data, the sedimentation rates down slope of the field containing the runoff plots were estimated to be 26 t-1 ha-1 a-1 using the 137Cs depth distribution profile and at 20 t-1 ha-1 a-1 using the MBM 2. In the lowest part of the watershed sedimentation rates of up to 51 t-1 ha-1 a-1 were estimated through the 137Cs depth distribution profile. These results were linked to long term erosion measurements (1994-2006) from runoff plots just up-slope from the sedimentation area. The average soil erosion reached 29 t ha-1 a-1 from the conventional tilled plot, 4 t ha-1 a-1 from the

  2. Analysis of the kinetic behaviour of iodine and caesium isotopes in the primary circuit of LWR's during severe fuel damage accidents

    International Nuclear Information System (INIS)

    This State of the Art report deals with the chemical behaviour of caesium and iodine in the primary system, focusing particularly on kinetic chemical aspects. In case of a postulated severe accident in a nuclear reactor, cesium and iodine fission products are among the major contributors to health harm because of their high volatility and radiotoxicity. The extent of the release of such fission products to the environment depends on the effectiveness of transport through different structures in the reactor coolant system and within the reactor building. The release from fuel has been briefly studied; only those aspects concerning to iodine and caesium chemical forms when released have been reviewed; nevertheless the emphasis has been put on the transport of such elements and their species through the primary system. Some thermochemical equilibrium studies, applied to primary circuit conditions in LWR's, have been analyzed. The revision of the few kinetic studies existing on this matter has shown that kinetic behaviour of iodine and caesium isotopes in the primary circuit is an aspect poorly studied, despite the fact that kinetic aspects could have great importance on the chemical species formed under certain conditions. Other phenomena affecting iodine and caesium transport, besides chemical reactions, such as interactions with surfaces, aerosols or other chemical species have also been examined from available information on diverse experiments

  3. Studies of nuclear waste migration in geologic media. Annual report, October 1978-September 1979

    International Nuclear Information System (INIS)

    Experimental results obtained this year confirm the results obtained in previous years - that nuclides migrating by fluid flow in rock often exhibit complex behavior not predicted by simple chromatographic-type models. A phenomenon found previously to lead to complex behavior for leached radionuclides is that the amount of adsorbed nuclide was not proportional to the nuclide concentration in solution (nonlinear adsorption isotherm). For cesium adsorption on limestone and on basalt, nonlinear isotherms were found this year to occur in the range of cesium concentrations in the groundwater of about 10-3 to 10-9M. Because cesium concentrations in this range can readily be attained by the leaching of solid waste by groundwater, the effects of nonlinear isotherms are germane to nuclide migration. This dependence of cesium migration on the leached concentration of cesium emphasizes the importance of treating the leaching and migration processes simultaneously such as is done in the leach-migration experiments performed in this work. The existence of nonlinear isotherms precludes the use of a single partition coefficient (K/sub d/) to describe cesium migration at an arbitrary cesium concentration above 10-9M. Nonetheless, nonlinear isotherms can be studied experimentally (e.g., to give K/sub d/ as a function of concentration) and effects of nonlinear adsorption can be predicted quantitatively. Comparison of results from column and batch tests indicate that, in addition to nonlinear adsorption, kinetic effects need to be considered in predicting nuclide migration from the partition coefficients measured in batch tests. Results of batch experiments of 2 weeks or longer duration pertained to migration expected only at the very lowest (< 50 m/y) groundwater flow rates of interest

  4. Stability properties of an isothermal accretion disk

    International Nuclear Information System (INIS)

    A local stability analysis of an isothermal, transonic accretion disk around a non-rotating black hole is used to infer the time-dependent behaviour of linear perturbations. The three modes in the problem are one viscous Lightman-Eardley mode, which is always stable, and two acoustic modes, which are always overstable. If the growth rate is required to be greater than the escape rate, then the acoustic modes become stable in the outer region, and unstable in the innermost region, if the viscosity parameter α is greater than 0.5. (orig.)

  5. Magnetostatic atmospheres: A family of isothermal solutions

    International Nuclear Information System (INIS)

    Most models of large scale solar magnetic fields assume either that the fields are potential or that they are force free. We present a new, analytic, two parameter family of magnetic fields in equilibrium with isothermal plasma in a gravitational field. We discuss these models from the viewpoint of the insight into the balance of magnetic pressure gradient, and gravitational forces that they provide. We show that substantial deviations from the potential field configuration are obtained for plasma β of order unity, and we emphasize the variety of possible relationships between isobars and magnetic fieldlines. (orig.)

  6. Isothermal calorimetry of enzymatic biodiesel reaction

    DEFF Research Database (Denmark)

    Fjerbæk Søtoft, Lene; Westh, Peter; Christensen, Knud Villy;

    2010-01-01

      Isothermal calorimetry ITC has been used to investigate enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by the immobilized lipase Novozym 435 at 40°C. The ITC-experiments clearly demonstrate the possibilities of investigating complex...... and composition change in the system, the heat of reaction at 40°C for the two systems has been determined to -9.8 ± 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and - 9.3 ± 0.7 kJ/mole when rapeseed oil and ethanol is used....

  7. Artificial neural network modeling of phase volume fraction of Ti alloy under isothermal and non-isothermal hot forging conditions

    International Nuclear Information System (INIS)

    An artificial neural network (ANN) model was applied to simulate the phase volume fraction of titanium alloy under isothermal and non-isothermal hot forging condition. For isothermal hot forging process, equilibrium phase volume fraction at specific temperature was predicted. For this purpose, chemical composition of six alloy elements (i.e. AI, Y, Fe, 0, N, and C) and specimen temperature were chosen as input parameter. After that, phase volume fraction under non-isothermal condition was simulated again. Input parameters consist of initial phase volume fraction, equilibrium phase volume fraction at specific temperature, cooling rate, and temperature.The ANN model was coupled with the FE simulation in order to predict the variation of phase volume fraction during non-isothermal forging. Ti-6AI-4Y alloy was forged under isothermal and non-isothermal condition and then, the resulting microstructures were compared with simulated data

  8. Migration and trade

    OpenAIRE

    Peter H. Egger; Ehrlich, Maximilian von; Nelson, Douglas R.

    2011-01-01

    Theoretical and empirical research in economics suggests that bilateral migration triggers bilateral trade through a number of channels. This paper assesses the functional form of the impact of migration on trade flows in a quasi-experimental setting. We provide evidence that the relationship is not log-linear. In particular, at small levels of migration (stocks) the elasticity of trade to migration is quite high, and it declines to zero at about 4,000 immigrants. If migration stocks exceed s...

  9. ISOTHERMAL PYROLYSIS OF KRAFT PULP MILL SLUDGE

    Directory of Open Access Journals (Sweden)

    Syamsudin Syamsudin

    2014-12-01

    Full Text Available Kraft pulp mill sludge cake composed of rejected wood fibers and activated sludge microorganisms. With a heating value about 14 MJ/kg (dried basis, this type of biomass had a potential as an alternative energy source. Unfortunately, it had an ash content of 27.6% and a moisture content of 80%. For reducing moisture content with minimum energy consumption, a combination of mechanical dewatering and thermal drying was studied previously. Meanwhile, experiments on isothermal pyrolysis had been carried out for further improvement on ultimate and proximate analysis of solid fuel. Final mass of char obtained from pyrolysis at 500oC was not significantly different from that of 700oC, so pyrolysis was considered to be optimum at 500oC. A char obtained from pyrolysis at temperature of 500oC had a pore surface area of 77.049 m2/g (highest among other temperatures. Kinetic of isothermal pyrolysis was well represented with a first order modified volumetric model with a frequency factor of 0.782 1/s and an activation of 34.050 kJ/mol.

  10. Segregation isotherms at the surfaces of oxide

    International Nuclear Information System (INIS)

    A non-Arrhenius segregation isotherm is derived which includes the change in the heat of segregation with surface coverage due to impurity-impurity interactions. It is shown that a linear dependence of log(xs) on the reciprocal temperature, where xs is the surface atomic ratio, can derive either from a constant heat of segregation, i.e., Arrhenius behavior, or from a heat of segregation that varies as xs-1. This isotherm is then used to calculate the equilibrium surface coverages of Ca at the {001} surface of MgO, Mg at the {0001} surface of α-Al2O3, Y at the {1012} and {1 bar 120} surfaces of α-Al2O3, and Na at the {111} and {110} surfaces of Li2O from the calculated heats of segregation. Where possible, comparisons are made with experiment. The more useful operational definition of the heat of segregation, namely, that derived from the measured coverage or that defined atomistically and obtained by calculation, is discussed

  11. Investigation of non-isothermal and isothermal gasification process of coal char using different kinetic model

    Institute of Scientific and Technical Information of China (English)

    Wang Guangwei; Zhang Jianliang; Shao Jiugang; Li Kejiang; Zuo Haibin

    2015-01-01

    Isothermal and non-isothermal gasification kinetics of coal char were investigated by using thermogravi-metric analysis (TGA) in CO2 atmosphere, and the experimental data were interpreted with the aids of random pore model (RPM), unreacted shrinking core model (URCM) and volume model (VM). With the increase of heating rate, gasification curve moves into high temperature zone and peak rate of gasification increases;with the increase of gasification temperature, gasification rate increases and the total time of gasification is shortened. The increase of both heating rate and gasification temperature could improve gasification process of coal char. Kinetics analysis indicates that experimental data agree better with the RPM than with the other two models. The apparent activation energy of non-isothermal and isother-mal gasification of coal char using RPM is 193.9 kJ/mol and 212.6 kJ/mol respectively, which are in accor-dance with reported data. Gasification process of coal char under different heating rates and different temperatures are predicted by the RPM derived in this study, and it is found that the RPM predicts the reaction process satisfactorily.

  12. The effect of organics on the sorption of strontium, caesium, iodine, neptunium, uranium and europium by glacial sand

    International Nuclear Information System (INIS)

    This study has been undertaken within the Commission of the European Communities MIRAGE II program on the determination of radionuclides in the geosphere. Preliminary batch sorption experiments have been carried out to study the behaviour of strontium, caesium, iodine, europium and uranium in a glacial sand-groundwater system. The effect of (i) the presence or absence of natural organic material and (ii) the addition of increasing quantities of EDTA or acetate on the distribution ratios was determined. In some cases speciation modelling was used as an aid to designing the experiments and interpreting the results. The aim of this work was to select suitable tracers for use in field experiments at Drigg. Cumbria and the results are intended to aid the design of future experiments rather than to provide a complete analysis of the radionuclide-organic interactions. 11 tabs., 49 refs

  13. Ultra-high and persistent optical depths of caesium in Kagom\\'e-type hollow-core photonic crystal fibres

    CERN Document Server

    Kaczmarek, Krzysztof T; Sprague, Michael R; Kolthammer, W Steven; Feizpour, Amir; Ledingham, Patrick M; Brecht, Benjamin; Poem, Eilon; Abdolvand, Amir; Russell, Philip St J; Walmsley, Ian A; Nunn, Joshua

    2015-01-01

    Alkali-filled hollow-core fibres are a promising medium for investigating light-matter interactions, especially at the single-photon level, due to the tight confinement of light and high optical depths achievable by light-induced atomic desorption. However, until now these large alkali vapour densities could only be generated for seconds at most once per day, severely limiting the practicality of the technology. Here we report the generation of highest observed transient ($>10^5$ for minutes) and highest observed persistent (>2000 for hours) optical depths of alkali vapours in hollow-core fibres to date, using a caesium-filled Kagom\\'e-type hollow-core photonic crystal fibre. Our results pave the way to light-matter interaction experiments in confined geometries requiring long operation times and large atomic number densities, such as single-photon-level light-matter interaction experiments and fundamental investigations of hot dense atomic gases.

  14. Solvothermal Synthesis of Caesium Tungsten Bronze in the Presence of Various Organic Acids and Its NIR Absorption Properties

    International Nuclear Information System (INIS)

    Nanoparticles of caesium tungsten bronze were successfully synthesized by solvothermal reactions in ethanol with the introduction of different organic fatty acids with various carbon numbers of 1 to 5. Compared to the sample prepared in pure ethanol, the samples obtained by mixed solvent of ethanol and fatty acids showed higher production yield, smaller particle size, more uniform particles size distribution and higher Cs/W atomic ratio. In addition, all of samples obtained using acids-ethanol mixed solvent exhibited higher visible light transmittance and greater NIR absorption performance, indicating the potential application for smart window and heat-ray shielding materials. The addition of acetic acid showed the best performance to facilitate the formation of well dispersed CsxWO3 regular nanorods, leading to its excellent optical properties.

  15. Determining the hyperfine structure constants of caesium 8S1/2 state aided by atomic coherence

    International Nuclear Information System (INIS)

    High-sensitivity spectroscopy of caesium's higher excited 8S1/2 state is obtained by a coherent two-photon transition via an intermediate resonance state. The ladder-type atomic system is driven by two counter-propagating low-power diode lasers, the probe laser being tuned to the transition from the ground state to the intermediate state (6S1/2–6P1/2), and the coupling laser to that between the intermediate and the final state (6P1/2–8S1/2). By locking the probe laser and scanning the coupling laser, the electromagnetically induced transparency (EIT) peaks appear in the probe transmission when the coupling laser resonates with each of the hyperfine levels. Compared with conventional EIT, where the signal-to-noise ratio is limited by the absorptive Doppler background, here these narrow-linewidth peaks have no Doppler background. The peak centres are well determined from theoretical fits to the experimental data. To accurately measure the 8S1/2 hyperfine structure splitting, we developed a simple method to eliminate error arising from the nonlinear frequency scanning by employing an optical waveguide phase modulator and a confocal Fabry–Perot cavity. The hyperfine structure constants of the caesium 8S1/2 state are obtained from hyperfine structure splitting measurements. Systematic effects from the ac-Stark and Zeeman shifts are studied. The measured hyperfine magnetic dipole constant A = (219.08 ± 0.12) MHz is consistent with previous results. (paper)

  16. Sorption of caesium and strontium by graphite materials in gas cooled high temperature reactors

    International Nuclear Information System (INIS)

    The experiments have revealed that coked phenol resin binder has got an extremely high sorption capacity for Cs and Sr. For this reason the sorption capacity of A3 matrix graphite for fuel elements exceeds the capacity of the highly graphitized material that does not contain this component. The strong chemical binding for Cs and Sr by chemisorption indicates a retention of these elements when the nucleus is heated up by accident. The release calculations carried out with definite sorption isotherms revealed a larger retention effect by sorption for Sr than for Cs. In this respect the matrix graphite in the ball-shaped fuel elements is of special importance for the retention. It is applied at German high temperature reactors and contains non-graphitized phenol resin binder. (orig./DG)

  17. Calculation of Thermodynamic Parameters for Freundlich and Temkin Isotherm Models

    Institute of Scientific and Technical Information of China (English)

    ZHANGZENGQIANG; ZHANGYIPING; 等

    1999-01-01

    Derivation of the Freundlich and Temkin isotherm models from the kinetic adsorption/desorption equations was carried out to calculate their thermodynamic equilibrium constants.The calculation formulase of three thermodynamic parameters,the standard molar Gibbs free energy change,the standard molar enthalpy change and the standard molar entropy change,of isothermal adsorption processes for Freundlich and Temkin isotherm models were deduced according to the relationship between the thermodynamic equilibrium constants and the temperature.

  18. Pyrolysis of petroleum pitches. 1. Non-isothermal kinetics

    OpenAIRE

    Okyay, Firuze; Yürüm, Yuda; Yurum, Yuda

    2012-01-01

    The chemical composition and reactivity of petroleum pitches under non-isothermal thermogravimetric conditions were studied. Thermogravimetry (TG) was used to study pyrolysis of petroleum pitches. Non-isothermal thermogravimetric data were used to evaluate the kinetics of the pyrolysis of this carbonaceous material. The paper reports application of Ozawa–Flynn–Wall model to deal with non-isothermal TG data for the evaluation of the activation energy corresponding to the pyrolysis of two diffe...

  19. Isothermal aging of three polyurethane elastomers

    Energy Technology Data Exchange (ETDEWEB)

    Guess, T.R.

    1996-05-01

    Two polyurethane systems, EN-7 and L-100, have a long history as encapsulants and coatings in Sandia programs. These materials contain significant amounts of toluene diisocyanate (TDI), a suspect human carcinogen. As part of efforts to reduce the use of hazardous materials in the workplace, PET-90A, a polyurethane with less than 0.1% free TDI, was identified as a candidate for new applications and as a replacement for the more hazardous polyurethanes in selected programs. This report documents the results of a two-year accelerated aging study of PET-90A, EN-7, and L-100 polyurethane elastomers to characterize the effect of 135{degrees}F isothermal aging on selected physical, electrical, mechanical and thermal properties. In general, there was very little change in properties over the two year period for the three elastomers. The largest changes occurred in EN-7, which is the polyurethane with the longest service history in Sandia applications.

  20. A family of lowered isothermal models

    CERN Document Server

    Gieles, Mark

    2015-01-01

    We present a family of self-consistent, spherical, lowered isothermal models, consisting of one or more mass components, with parameterised prescriptions for the energy truncation and for the amount of radially biased pressure anisotropy. The models are particularly suited to describe the phase-space density of stars in tidally limited, mass-segregated star clusters in all stages of their life-cycle. The models extend a family of isotropic, single-mass models by Gomez-Leyton and Velazquez, of which the well-known Woolley, King and Wilson (in the non-rotating and isotropic limit) models are members. We derive analytic expressions for the density and velocity dispersion components in terms of potential and radius, and introduce a fast model solver in PYTHON (LIMEPY), that can be used for data fitting or for generating discrete samples.

  1. A family of lowered isothermal models

    Science.gov (United States)

    Gieles, Mark; Zocchi, Alice

    2015-11-01

    We present a family of self-consistent, spherical, lowered isothermal models, consisting of one or more mass components, with parametrized prescriptions for the energy truncation and for the amount of radially biased pressure anisotropy. The models are particularly suited to describe the phase-space density of stars in tidally limited, mass-segregated star clusters in all stages of their life-cycle. The models extend a family of isotropic, single-mass models by Gomez-Leyton and Velazquez, of which the well-known Woolley, King and Wilson (in the non-rotating and isotropic limit) models are members. We derive analytic expressions for the density and velocity dispersion components in terms of potential and radius, and introduce a fast model solver in PYTHON (LIMEPY), that can be used for data fitting or for generating discrete samples.

  2. Non-isothermal effects on Be disks

    CERN Document Server

    Vieira, Rodrigo G; Bjorkman, Jon E

    2016-01-01

    In the last decade, the viscous decretion disk model has emerged as the new paradigm for Be star disks. In this contribution, we propose a simple analytical model to estimate the continuum infrared excess arising from these circumstellar disks, in the light of the currently accepted scenario. We demonstrate that the disk can be satisfactorily described by a two component system: an inner optically thick region, which we call the pseudo-photosphere, and a diffuse outer part. In particular, a direct connexion between the disk brightness profile and the thermal structure is derived, and then confronted to realistic numerical simulations. This result quantifies how the non-isothermality of the disk ultimately affects both infrared measured fluxes and visibilities.

  3. On migration of primary/peritectic interface during interrupted directional solidification of Sn-Ni peritectic alloy

    Science.gov (United States)

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie; Fu, Hengzhi

    2016-04-01

    The migration of the primary/peritectic interface in local isothermal condition is observed in dendritic structure of Sn–Ni peritectic alloy after experiencing interrupted directional solidification. It was observed that this migration of primary Ni3Sn2/peritectic Ni3Sn4 interface towards the primary Ni3Sn2 phase was accompanied by migration of liquid film located at this interface. The migration velocity of this interface was confirmed to be much faster than that of peritectic transformation, so this migration was mostly caused by superheating of primary Ni3Sn2 phase below TP, leading to nucleation and migration of liquid film at this interface. This migration can be classified as a kind of liquid film migration (LFM), and the migration velocity at the horizontal direction has been confirmed to be much faster than that along the direction of temperature gradient. Analytical prediction has shown that the migration of liquid film could be divided into two stages depending on whether primary phase exists below TP. If the isothermal annealing time is not long enough, both the liquid film and the primary/peritectic interface migrate towards the primary phase until the superheated primary phase has all been dissolved. Then, this migration process towards higher temperature is controlled by temperature gradient zone melting (TGZM).

  4. On migration of primary/peritectic interface during interrupted directional solidification of Sn-Ni peritectic alloy

    Science.gov (United States)

    Peng, Peng; Li, Xinzhong; Li, Jiangong; Su, Yanqing; Guo, Jingjie; Fu, Hengzhi

    2016-01-01

    The migration of the primary/peritectic interface in local isothermal condition is observed in dendritic structure of Sn–Ni peritectic alloy after experiencing interrupted directional solidification. It was observed that this migration of primary Ni3Sn2/peritectic Ni3Sn4 interface towards the primary Ni3Sn2 phase was accompanied by migration of liquid film located at this interface. The migration velocity of this interface was confirmed to be much faster than that of peritectic transformation, so this migration was mostly caused by superheating of primary Ni3Sn2 phase below TP, leading to nucleation and migration of liquid film at this interface. This migration can be classified as a kind of liquid film migration (LFM), and the migration velocity at the horizontal direction has been confirmed to be much faster than that along the direction of temperature gradient. Analytical prediction has shown that the migration of liquid film could be divided into two stages depending on whether primary phase exists below TP. If the isothermal annealing time is not long enough, both the liquid film and the primary/peritectic interface migrate towards the primary phase until the superheated primary phase has all been dissolved. Then, this migration process towards higher temperature is controlled by temperature gradient zone melting (TGZM). PMID:27075006

  5. Migration and revolution

    Directory of Open Access Journals (Sweden)

    Nando Sigona

    2012-06-01

    Full Text Available The Arab Spring has not radically transformed migration patterns in the Mediterranean, and the label ‘migration crisis’ does not do justice to the composite and stratified reality.

  6. Structure of magnesium alloy MA14 after multistep isothermal forging and subsequent isothermal rolling

    Science.gov (United States)

    Nugmanov, D. R.; Sitdikov, O. Sh.; Markushev, M. V.

    2015-10-01

    Optical metallography and electron microscopy have been used to analyze the structural changes in magnesium MA14 alloy subjected to processing that combines multistep isothermal forging and isothermal rolling. It has been found that forging of a bulk workpiece leads to the formation of a structure, 85-90% of which consists of recrystallized grains with an average size of less than 5 µm. Subsequent rolling results in a completely recrystallized structure with a grain size of 1-2 µm. It is shown that the resultant structural states are characterized by grain size nonuniformity inherited from the initial hot-pressed semi-finished product. The nature and features of crystallization processes that take place in the alloy during processing are discussed.

  7. International Migration and Remittances

    OpenAIRE

    Dattatray Sitaram Bagade

    2012-01-01

    Human migration is a physical movement by human beings from one geographical areato another geographical area. Migration is internal as well as external. At theinternational level, no universally accepted definition for “Migrant” exists. The UniteNations defines “migration as an individual who has resided in a foreign country formore than one year irrespective of the causes, voluntary or involuntary, and the means,regular or irregular, used migrate”. Key terms of migrations is documented migr...

  8. Migration, Remittances and Growth

    OpenAIRE

    Nurgul Ukueva

    2011-01-01

    This paper analyzes the effect of migration and remittances on a small, open, migrant-sending country in the context of an endogenous growth model with technology transfers. The paper demonstrates that, due to a dynamic feedback effect from economic conditions to migration and from migration to economic development in an economy exposed to migration, initial conditions can determine its long-run steady state, leading to the rise of vicious or virtues circles of development. Countries with a l...

  9. Essays on temporary migration

    OpenAIRE

    Mestres Domenech, J.

    2012-01-01

    My thesis dissertation focuses on the temporariness of migration, its diverse effects as well as on migration selection. The first paper, A Dynamic Model of Return Migration analyzes the decision process underlying return migration using a dynamic model. We explain how migrants decide whether to stay or to go back to their home country together with their savings and consumption decisions. We simulate our model with return intentions and perform policy simulations. The se...

  10. On Marriage and Migration

    OpenAIRE

    Stark, Oded

    1988-01-01

    Marriage, migration and related phenomena such as marital stability, fertility and investment in human capital may be better explained by studying marriage and migration jointly. We thus proceed in this paper to explore the role of migration in obtaining joint labour-market and marriage-market equilibrium. This facilitates identification of several novel and testable hypotheses.

  11. Experimental research of gas flows through isothermal and non-isothermal membranes

    Science.gov (United States)

    Nikolskiy, Yu. V.; Friedlander, O. G.

    2012-11-01

    In specialized test bench and in vacuum aerodynamic facilities VAT-2M TsAGI three types of a gas flows with observed kinetic effects were researched. Firstly, the flow through the membrane with uniform temperature was investigated. The dependence of flow rate through membranes on pressure drop across it was measured at various values of permeability. The experimental data at various flow regimes in the pores were compared with numerical data. The comparison gives the opportunity to associate the model perforated membrane with definite diameter of perforation channels and with definite permeability to each porous membrane with intricate pores. Flow rate through real and model membranes are the same ones for two limit regimes: the free-molecular regime and the Stokes ones. For experimental research of a gas flows induced by temperature difference across membrane the method of creation such temperature difference (uniform on membrane surface) was used. In this method thermoelectric effect is utilized. The dependence of thermo-transpiration flow rate and thermo-molecular pressure difference across non-isothermal membrane (for zero flow rate) on gas pressure were measured. The comparison of results of direct and indirect measurements of the velocity of thermo-transpiration was carried out. In the second case the flow rate of thermal transpiration was calculated by the experimental results on thermo-molecular pressure difference across non-isothermal membrane and the results of measurement of pressure driven flow through isothermal membrane.

  12. Integral migration and source-term experiments on cement and bitumen waste forms

    International Nuclear Information System (INIS)

    This is the final report of a programme of research which formed a part of the CEC joint research project into radionuclide migration in the geosphere (MIRAGE). This study addressed the aspects of integral migration and source term. The integral migration experiment simulated, in the laboratory, the intrusion of water into the repository, the leaching of radionuclides from two intermediate-level waste-forms and the subsequent migration through the geosphere. The simulation consisted of a source of natural ground water which flowed over a sample of waste-form, at a controlled redox potential, and then through backfill and geological material packed in columns. The two waste forms used here were cemented waste from the WAK plant at Karlsruhe in the Federal Republic of Germany and bitumenized intermediate concentrates from the Marcoule plant in France. The soluble fission products such as caesium were rapidly released from the cemented waste but the actinides, and technetium in the reduced state, were retained in the waste-form. The released of all nuclides from the bitumenized waste was very low

  13. Integral migration and source term experiments on cement and bitumen waste forms

    International Nuclear Information System (INIS)

    This is the final report of a programme of research which formed a part of the CEC joint research project into radionuclide migration in the geosphere (MIRAGE). This study addressed the aspects of integral migration and source term. The integral migration experiment simulated, in the laboratory, the intrusion of water into the repository, the leaching of radionuclides from two intermediate level wasteforms and the subsequent migration through the geosphere. The simulation consisted of a source of natural ground water which flowed over a sample of wasteform, at a controlled redox potential, and then through backfill and geological material packed in columns. The two wasteforms used here were cemented waste from the WAK plant at Karlsruhe, W. Germany and bitumenised intermediate concentrates from the Marcoule plant in France. The soluble fission products such as caesium wire rapidly released from the cemented waste but the actinides, and technetium in the reduced state, were retained in the wasteform. The release of all nuclides from the bitumenised waste was very low. (author)

  14. Financial Statement Audit Report of Isothermal Community College.

    Science.gov (United States)

    Campbell, Ralph

    This report presents the results of the Isothermal Community College financial statement audit for the fiscal year ending on June 30, 1998. Isothermal Community College is a component of the State of North Carolina, thus the authority to audit is granted by Article 5A of G.S. 147. The accounts and operations of the institution were subject to…

  15. Influence of viscosity and the adiabatic index on planetary migration

    Science.gov (United States)

    Bitsch, B.; Boley, A.; Kley, W.

    2013-02-01

    Context. The strength and direction of migration of low mass embedded planets depends on the disk's thermodynamic state. It has been shown that in active disks, where the internal dissipation is balanced by radiative transport, migration can be directed outwards, a process which extends the lifetime of growing embryos. Very important parameters determining the structure of disks, and hence the direction of migration, are the viscosity and the adiabatic index. Aims: In this paper we investigate the influence of different viscosity prescriptions (α-type and constant) and adiabatic indices on disk structures. We then determine how this affects the migration rate of planets embedded in such disks. Methods: We perform three-dimensional numerical simulations of accretion disks with embedded planets. We use the explicit/implicit hydrodynamical code NIRVANA that includes full tensor viscosity and radiation transport in the flux-limited diffusion approximation, as well as a proper equation of state for molecular hydrogen. The migration of embedded 20 MEarth planets is studied. Results: Low-viscosity disks have cooler temperatures and the migration rates of embedded planets tend toward the isothermal limit. Hence, in these disks, planets migrate inwards even in the fully radiative case. The effect of outward migration can only be sustained if the viscosity in the disk is large. Overall, the differences between the treatments for the equation of state seem to play a more important role in disks with higher viscosity. A change in the adiabatic index and in the viscosity changes the zero-torque radius that separates inward from outward migration. Conclusions: For larger viscosities, temperatures in the disk become higher and the zero-torque radius moves to larger radii, allowing outward migration of a 20-MEarth planet to persist over an extended radial range. In combination with large disk masses, this may allow for an extended period of the outward migration of growing

  16. Patterns of migration in Tanzania.

    OpenAIRE

    Bernstein, H

    1981-01-01

    ILO pub-wep pub. Working paper identifying internal migration patterns and employment implications in Tanzania - discusses reasons for migration, types (seasonal workers, permanent, etc.), Migration within rural areas or urban areas, rural migration, land settlement trends, etc. References.)

  17. Isothermal composite adsorbent. Part I: Thermal characterisation

    International Nuclear Information System (INIS)

    Adsorption and desorption are respectively exo and endothermic phenomena leading to significant temperature changes in adsorption columns. Enhanced efficiency of a sorption process could be obtained under isothermal conditions, either for gas storage, purification or separation applications. The heat transfer within the adsorbent beds can be managed in situ, using thermal energy storage material: a phase change materials (PCM) for example. The thermal behaviour of a mixture of activated carbon and PCM during CO2 adsorption has been studied. The thermal characteristics of the involved materials have been determined and experiments carried out to highlight the positive effect of the PCM to reduce the CO2 adsorption heat effects on an activated carbon bed. Calorimetry was the technique used for all the thermal characterisations. It appears that the heat effects induced by CO2 adsorption are reduced by the presence of the PCM together with the adsorbent. The endothermic effect of fusion balances the heat effect of adsorption and significantly reduces the temperature changes

  18. Isothermal Dilatometric Study of Sintering in Kaolin

    Science.gov (United States)

    Ondruška, Ján; Trník, Anton; Keppert, Martin; Medved', Igor; Vozár, Libor

    2014-10-01

    Solid-state sintering for kaolin samples was studied by dilatometric measurements in the isothermal regime in the temperature range from 600 °C to 1100 °C. The relative expansion was measured for a period of 10h. For the temperatures up to 850 °C, we observed only a small shrinkage (less than 0.5 %), most of which took place within the first 3h of the measurements. For the temperatures above 850 °C, a significant shrinkage occurred for the whole measured time interval and reached up to 2.7 %. Anomalous behavior—a decrease in the shrinkage with the temperature—was observed in the range from 700 °C to 850 °C. The dilatometric measurements are supplemented by porosity distribution measurements. The standard spherical-grains microscopic model was applied to determine that for the initial stages of the sintering process, grain boundary diffusion was the dominant mechanism at lower temperatures (600 °C to 850 °C), whereas lattice diffusion was dominant at higher temperatures (900 °C, 1050 °C, and 1100 °C).

  19. Non isothermal drying process optimisation - Drying of clay tiles

    Science.gov (United States)

    Vasić, M.; Radojević, Z.

    2015-11-01

    In our previous studies we have developed a model for determination of the variable effective diffusivity and identification of the exact transition points between possible drying mechanisms. The next goal was to develop a drying regime which could in advance characterize the real non isothermal process of drying clay tiles. In order to do this four isothermal experiments were recorded. Temperature and humidity were maintained at 350C / 75%; 450C / 70%; 450C / 60% and 500C / 60%; respectively in each experiment. All experimentally collected data were analyzed and the exact transition points between possible drying mechanisms were detected. Characteristic drying period (time) for each isothermal drying mechanism was also detected. The real, non-isothermal drying process was approximated by 5 segments. In each of these segments approximately isothermal drying condition were maintained. Temperature and humidity of the drying air, in the first four segments, was maintained on the same level as in recorded isothermal experiments while in the fifth segment, it were maintained at 700C / 40%. The duration of the first four segments were calculated from the diagrams Deff - t respectively for each experiment. The clay tile in experiment five was dried without cracking using the proposed non isothermal drying regime.

  20. Radioactive caesium in fish in Swedish lakes 1986-1988 -general pattern related to fallout and lake characteristics

    International Nuclear Information System (INIS)

    This study investigates how the concentration of 137Cs varied geographically in Sweden during 1986, 1987 and 1988 in different fish species to study how different lake properties influence the 137Cs uptake in fish, to try to develop a load diagram for lakes when 137Cs in fish is used as an effect parameter, and to study how the caesium concentration varies seasonally and with fish size. A register was compiled, containing a broad set of data from 644 Swedish lakes. The median 137Cs concentration in fish increased between 1986 and 1987 by between 13% (trout) and 240% (pike). The increase between 1987 and 1988 has stagnated for most species, but not for pike where the concentration increased 82% in the 'the median lake'. The in-lake, between-lake and temporal variations are large and differ from species to species. About 14 000 lakes in Sweden had fish ('100 g perch') with 137Cs concentrations above 1500 Bq/kg (w/w) during the autumn of 1987. Apart from the radioactive fallout, the water retention time is the individual factors of greatest importance for the variability of 137Cs concentration in fish between these lakes. Lake water hardness and/or conductivity also influence the uptake of 137Cs in fish. (author)

  1. Determining soil redistribution in Dian Lake catchment by combined use of caesium-137 and selected chemical properties

    Institute of Scientific and Technical Information of China (English)

    Zhang Mingli; Yang Hao; Xu Congan; Wang Yihong

    2009-01-01

    Recent development in the use of the environmental radionuclide caesium-137 for documenting rates and patterns of soil redistribution on the cultivated or uncultivated land and estimating rates of sediment deposition on floodplains represents an important advance that overcomes many of the limitations' of the conventional techniques commonly applied in such investigations.A study on soil redistribution (including soil erosion and deposition) was carried out in the Dian Lake catchment,Yunnan Province,using 137Cs and selected chemical properties.The average soil erosion rate was 1,280.2 t km-2yr-1.Soil erosion rate occurring on different parts of the slope was significantly different on different parts of the slope,increasing from the top,the bottom to the middle slope.The average soil erosion rate is also different with the land use type and that of the cultivated land (1,672.8 t km-2 yr-1) is higher than of the uncultivated land (1,161.2 t km-2yr-1).The result shows that landform,slope gradient and land use type are key factors that influence the size of soil erosion.In addition,we also find the SOC and TN contents and amount of the soil erosion to be correlated in the soil.With the soil erosion occurring,there are land degradation and the local eco-environmental problems,such as water eutrophication in Dian Lake

  2. Long range transport of caesium isotopes from temperate latitudes to the equatorial zone during the winter monsoon period

    International Nuclear Information System (INIS)

    An air radioactivity monitoring study carried out in Dalat, Vietnam since 1986 has revealed distinct peaks of caesium isotope concentrations in air and fallout during December-January, when the monthly average air temperature was lowest and dry fallout dominated. These peaks provide evidence of the intrusion of more radioactive cold air masses from temperate northern latitudes during the development of large-scale anti cyclones, frequently observed in the most active winter monsoon period. High dry fallout velocity (about 10 cm/s) determined from the measured concentrations, clearly demonstrates one of the most relevant features of cold air masses: behind the cold front, vertical air motion is descending. The role of other processes, such as injection of radioactive air from stratosphere and local resuspension of soil dust, has been shown to be insignificant. The interpretation of the experimental results was based on the analysis of environmental -meteorological factors as well as the behaviour of other naturally-occurring radionuclides. (author). 7 refs, 2 figs

  3. Spatial variability of caesium-137 inventories at reference sites: an example from two contrasting sites in England and Zimbabwe

    International Nuclear Information System (INIS)

    Bomb-derived caesium-137 (137Cs) fallout has been widely used to investigate rates and patterns of soil erosion and sediment deposition. Within this approach considerable importance is placed on establishing the local total 137Cs fallout or inventory at a reference site. However, relatively little information currently exists concerning the variability of 137Cs inventories at reference sites. This paper reports an investigation of the spatial variability of 137Cs inventories at two contrasting reference sites at Yendacott, England and Msana, Zimbabwe. Replicate bulk soil cores were collected at the intersections of a grid, yielding 60 and 27 samples from Yendacott and Msana, respectively. Although the total variability may be derived from four sources (random spatial, systematic spatial, sampling and measurement), the observed variability was in both cases primarily due to random spatial variations in 137Cs inventories. The reference inventory range (at the 95% confidence level) was 205-230 and 17.0-33.4 mBq cm-2 for the Yendacott and Msana sites, respectively. (Author)

  4. Change of the radionuclide content of landscapes contamination in the small catchment at the Bryansk-Belarus caesium spot

    International Nuclear Information System (INIS)

    The results of the joint Russian-Belarus RFBR-BelRFBR project no. 02-05-81011 will be shown. Information on the spatial redistribution of 137Cs within small catchment and through the connected landscapes is an important background for estimating consequences of the Chernobyl contamination. 137Cs can be used as a tracer for study the direction and intensity of geo-chemical processes in landscapes of small catchment. The experimental data on the modern radionuclide content of soil and plant contamination have been received at the expeditions of 2000-2004 in the regions situated on distances 50, 150 and 250 km from the Chernobyl NPP on territories of Belarus and Russia. Some small catchment in the Dnieper basin have been studied (Braginka, Sozh and Moskovka rivers). The content of 137Cs, 90Sr, 239+240Pu and 241Am in soils will be presented. The modern variability of contamination levels in each of connected landscapes will be compared with the variability estimated immediately after the Chernobyl accident. The high spatial fixation of Caesium spots by the Polessye landscapes will be shown. (author)

  5. Isothermal sintering kinetics of UOsub(2+x)

    International Nuclear Information System (INIS)

    The isothermal sintering kinetics of UOsub(2+x) were studied by measuring the densification rate in an optical dilatometer developed for this purpose. The sintering was conducted at constant temperature by using thin UOsub(2+x) compacts with a constant nonstoichiometry. The oxygen partial pressure in the sintering atmosphere was continuously measured by a stabilized ZrO2 solid electrolyte cell, particular attention being paid to the starting conditions of the ideal sintering. An empirical densification rate equation that describes the sintering kinetics within a large range was verified: density range 52 - 83% of the theoretical density, temperature range 1000 degC - 1550 degC, nonstoichiometry range Psub(O2)=10sup(-15.3)-10sup(-8.4)Pa, at 1100 degC, sintering time 12 s - 281 h. The effect of temperature on the sintering rate was compatible with the values reported in the literature for the effect of temperature on the uranium self-diffusion, the determined activation energy being 432 +- 13 kJ/mole. It was also noted that the uranium self-diffusion is suitable as the dominating factor in the sintering kinetics of UOsub(2+x). The rise in temperature from 1000 degC to 1550 degC increased the densification rate constant k 40-fold, and the change in oxygen partial pressure from Psub(O2)=10sup(-15.3) to Psub(O2)=10sup(-8.4) Pa at 1100 degC 4-fold. At 800 degC and at composition UOsub(2.1) a sintering rate was measured that corresponds to the sintering rate of a stoichiometric compact at 1320 degC. With the method applied in the present study and the verified empirical equation, the effect of the various factors on the sintering of the uranium dioxide compacts used as fuel elements can be studied accurately. (author)

  6. Isothermal reduction of titanomagnetite concentrates containing coal

    Institute of Scientific and Technical Information of China (English)

    Tu Hu; Xue-wei Lü; Chen-guang Bai; Gui-bao Qiu

    2014-01-01

    The isothermal reduction of the Panzhihua titanomagnetite concentrates (PTC) briquette containing coal under argon atmosphere was investigated by thermogravimetry in an electric resistance furnace within the temperature range of 1250-1350°C. The samples reduced in argon at 1350°C for different time were examined by X-ray diffraction (XRD) analysis. Model-fitting and model-free methods were used to evaluate the apparent activation energy of the reduction reaction. It is found that the reduction rate is very fast at the early stage, and then, at a later stage, the reduction rate becomes slow and decreases gradually to the end of the reduction. It is also observed that the reduction of PTC by coal depends greatly on the temperature. At high temperatures, the reduction degree reaches high values faster and the final value achieved is higher than at low temperatures. The final phase composition of the reduced PTC-coal briquette consists in iron and fer-rous-pseudobrookite (FeTi2O5), while Fe2.75Ti0.25O4, Fe2.5Ti0.5O4, Fe2.25Ti0.75O4, ilmenite (FeTiO3) and wustite (FeO) are intermediate products. The reaction rate is controlled by the phase boundary reaction for reduction degree less than 0.2 with an apparent activation energy of about 68 kJ·mol-1 and by three-dimensional diffusion for reduction degree greater than 0.75 with an apparent activation energy of about 134 kJ·mol-1. For the reduction degree in the range of 0.2-0.75, the reaction rate is under mixed control, and the activation energy increases with the increase of the reduction degree.

  7. Cascade theory for isothermal atmosphere, 1

    International Nuclear Information System (INIS)

    A cascade shower formed by the gamma-ray produced at the depth of tsub(o)(c. u) in isothermal atmosphere was calculated by approx. A, Landau, and its result is reported. The electromagnetic cascade theory in the atmosphere is necessary in order to obtain the lateral structure of electromagnetic components in EAS calculation, and the result in case of uniform substance has been utilized. Further, effects of the generating point tsub(o) of gamma ray of EAS must be learned as it is not emitted at the top of atmosphere. Therefore, the calculation of the cascade in atmosphere has been performed. in the case that the energy spectra of incident photons are Esub(o)sup(-γ-1) dEsub(o) is plotted, when γ is 1.0, 1.5, and 2.0. As tsub(o) becomes larger, it conforms to the case of uniform substance; whereas when tsub(o) is o, the difference from unifrom substance is maximum. The result of calculation by saddle point approximation was compared with Misaki's result in the case of uniform substance. The difference from unifrom substance is about twice as compared by the Moliere unit at the observed point. If the Moliere unit over several cascade units is used, good approximation can be obtained as Kamata-Nishimura have pointed out. Further, it is shown that over how much cascade units the Moliere unit used must be taken so that E)sup(2)>is in conformity, when tsub(o) is o, and Esub(o)/E is 104. Numerical calculation of f(a1, a2, t, tsub(o)) is appended. (Iwakiri, K.)

  8. Can inter-cultivar variation in caesium and strontium uptake reduce contamination of forage grasses? - Can inter-cultivar variation in caesium and strontium accumulation by forage grasses be used to reduce contamination of cows' milk in radiologically contaminated areas?

    Energy Technology Data Exchange (ETDEWEB)

    Penrose, B. [NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Lancaster, LA1 4AP (United Kingdom); School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD (United Kingdom); Beresford, N. [NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Lancaster, LA1 4AP (United Kingdom); Broadley, M.; Crout, N.M.J.; King, J.; Young, S. [School of Biosciences, University of Nottingham, Sutton Bonington Campus, Leicestershire, LE12 5RD (United Kingdom); Lovatt, A. [Institute of Biological, Environmental and Rural Sciences (IBERS), Aberystwyth University, Gogerddan, Aberystwyth, Ceredigion, SY23 3E E (United Kingdom); Thomson, R. [Science and Advice for Scottish Agriculture (SASA), Roddinglaw Road, Edinburgh, EH12 9FJ (United Kingdom)

    2014-07-01

    Radiocaesium and radiostrontium primarily enter the food chain via plant root uptake, including indirectly via animal fodders. Inter-species variation in caesium and strontium accumulation in plants has previously been reported to be over two orders of magnitude. This variation could be exploited to select crops with relatively low uptake to reduce transfer of these radionuclides to consumers in contaminated areas. Exploiting intra-species (i.e. inter-cultivar) variation in caesium and strontium uptake has not yet been evaluated as a remediation strategy as sufficient data have not been available. As cows' milk has been one of the main contributors to human dose following the Chernobyl and Mayak accidents, we have chosen to focus on elucidating the extent and nature of inter-cultivar variation in caesium and strontium uptake in forage grasses. A total of 412 cultivars from four species of forage grass; perennial ryegrass (Lolium perenne; 284 cultivars), Italian ryegrass (Lolium multiflorum; 17 cultivars), hybrid ryegrass (Lolium hybridum; 101 cultivars) and tall fescue (Festuca arundinacea; 10 cultivars) were sampled from 20 sets of experimental plots in Aberystwyth (Wales, UK) and Edinburgh (Scotland, UK). Fifty-nine cultivars were grown in both locations. At least three replicates of the same cultivar were grown in each set of plots. Vegetation samples from 2208 plots were collected both in spring 2013 (May-June) and summer 2013 (August-September). The samples were oven-dried and milled then analysed for elemental composition using inductively coupled plasma mass spectrometry (ICP-MS). Stable caesium and strontium were measured as a proxy measurement for radiocaesium and radiostrontium concentrations. Concentrations of chemical analogues of caesium and strontium (potassium and calcium) and a number of other elements were measured. Soil samples from the experimental plots were also collected, dried, milled and analysed using ICP-MS. This paper will present

  9. Total Correlation Function Integrals and Isothermal Compressibilities from Molecular Simulations

    DEFF Research Database (Denmark)

    Wedberg, Rasmus; Peters, Günther H.j.; Abildskov, Jens

    2008-01-01

    Generation of thermodynamic data, here compressed liquid density and isothermal compressibility data, using molecular dynamics simulations is investigated. Five normal alkane systems are simulated at three different state points. We compare two main approaches to isothermal compressibilities: (1...... approximately the same amount of time. This suggests that computation of total correlation function integrals is a route to isothermal compressibility, as accurate and fast as well-established benchmark techniques. A crucial step is the integration of the radial distribution function. To obtain sensible results...

  10. Modeling and Prediction of Soil Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Moldrup, Per;

    2015-01-01

    Soil water vapor sorption isotherms describe the relationship between water activity (aw) and moisture content along adsorption and desorption paths. The isotherms are important for modeling numerous soil processes and are also used to estimate several soil (specific surface area, clay content...... wide range of soils; and (ii) develop and test regression models for estimating the isotherms from clay content. Preliminary results show reasonable fits of the majority of the investigated empirical and theoretical models to the measured data although some models were not capable to fit both sorption...

  11. Phase field modeling of dendritic coarsening during isothermal

    Directory of Open Access Journals (Sweden)

    Zhang Yutuo

    2011-08-01

    Full Text Available Dendritic coarsening in Al-2mol%Si alloy during isothermal solidification at 880K was investigated by phase field modeling. Three coarsening mechanisms operate in the alloy: (a melting of small dendrite arms; (b coalescence of dendrites near the tips leading to the entrapment of liquid droplets; (c smoothing of dendrites. Dendrite melting is found to be dominant in the stage of dendritic growth, whereas coalescence of dendrites and smoothing of dendrites are dominant during isothermal holding. The simulated results provide a better understanding of dendrite coarsening during isothermal solidification.

  12. Radon depth migration

    International Nuclear Information System (INIS)

    A depth migration method is presented that used Radon-transformed common-source seismograms as input. It is shown that the Radon depth migration method can be extended to spatially varying velocity depth models by using asymptotic ray theory (ART) to construct wavefield continuation operators. These operators downward continue an incident receiver-array plane wave and an assumed point-source wavefield into the subsurface. The migration velocity model is constrain to have longer characteristic wavelengths than the dominant source wavelength such that the ART approximations for the continuation operators are valid. This method is used successfully to migrate two synthetic data examples: (1) a point diffractor, and (2) a dipping layer and syncline interface model. It is shown that the Radon migration method has a computational advantage over the standard Kirchhoff migration method in that fewer rays are computed in a main memory implementation

  13. Spatial distribution of caesium-137 in soil cover of background terrestrial ecosystems, Central European Russia

    Energy Technology Data Exchange (ETDEWEB)

    Paramonova, Tatiana A. [Radioecology and Ecotoxicology Department of Soil Science Faculty, Moscow State Lomonosov University, 119234 Moscow (Russian Federation); Shamshurina, Evgenia N. [Laboratory of soil erosion and fluvial processes of Geography Faculty, Moscow State Lomonosov University, 119234 Moscow (Russian Federation)

    2014-07-01

    ¹³⁷Cs - the main long-living anthropogenic radionuclide - arrived in mass at Russian terrestrial ecosystems after nuclear tests in the atmosphere in 1960-yy. and after Chernobyl accident in 1986 y., but in spite of a long period since these events soil cover contamination by ¹³⁷Cs is considered as extremely resistant due to its firmly fixation by soil solid matter and a long half-life of the radionuclide. Wide-scale investigation in maximal diversity of natural, semi-natural and anthropogenic landscapes of Central European Russia (more than 400 soils samples from Vologda, Yaroslavl, Ivanovo, Tver regions which are representative for the southern taiga zone) demonstrates that modern average specific activity of ¹³⁷Cs in the upper 15-cm layer of soil is 11±3 Bq/kg (contamination density 0.05±0.01 Ci/km²), that is fully ecologically acceptable. It is important that the average concentrations of ¹³⁷Cs in the soil cover of individual regions are close to each other. The most likely these average values are approximate assessment of background radioactive contamination of soils in central European Russia outside of the immediate Chernobyl trace. At the same time approximately 3% of soils are characterized by elevated ¹³⁷Cs content - 62-98 Bq/kg (0.24-0.43 Ci/km²), that indicates the presence of low radioactive spots on the territory and may be considered as local Chernobyl fallout. All of them attribute with forest soils which are commonly characterized by considerably more high accumulation of ¹³⁷Cs (18±5 Bq/kg, 0.06±0.01 Ci/km²) due to advanced absorbing surface of trees. Agricultural lands (plagued or under meadows) and soils of industrial plots with scarce vegetation contain only 6±2 Bq/kg (0.03±0.01 Ci/km²) of ¹³⁷Cs. About 84-92% of ¹³⁷Cs are concentrated in the upper 15-cm layer of natural soils or in Ap horizon of plagued soils, thus vertical migration of radionuclide is very slow in spite of ~30 years after Chernobyl

  14. Spatial distribution of caesium-137 in soil cover of background terrestrial ecosystems, Central European Russia

    International Nuclear Information System (INIS)

    137Cs - the main long-living anthropogenic radionuclide - arrived in mass at Russian terrestrial ecosystems after nuclear tests in the atmosphere in 1960-yy. and after Chernobyl accident in 1986 y., but in spite of a long period since these events soil cover contamination by 137Cs is considered as extremely resistant due to its firmly fixation by soil solid matter and a long half-life of the radionuclide. Wide-scale investigation in maximal diversity of natural, semi-natural and anthropogenic landscapes of Central European Russia (more than 400 soils samples from Vologda, Yaroslavl, Ivanovo, Tver regions which are representative for the southern taiga zone) demonstrates that modern average specific activity of 137Cs in the upper 15-cm layer of soil is 11±3 Bq/kg (contamination density 0.05±0.01 Ci/km2), that is fully ecologically acceptable. It is important that the average concentrations of 137Cs in the soil cover of individual regions are close to each other. The most likely these average values are approximate assessment of background radioactive contamination of soils in central European Russia outside of the immediate Chernobyl trace. At the same time approximately 3% of soils are characterized by elevated 137Cs content - 62-98 Bq/kg (0.24-0.43 Ci/km2), that indicates the presence of low radioactive spots on the territory and may be considered as local Chernobyl fallout. All of them attribute with forest soils which are commonly characterized by considerably more high accumulation of 137Cs (18±5 Bq/kg, 0.06±0.01 Ci/km2) due to advanced absorbing surface of trees. Agricultural lands (plagued or under meadows) and soils of industrial plots with scarce vegetation contain only 6±2 Bq/kg (0.03±0.01 Ci/km2) of 137Cs. About 84-92% of 137Cs are concentrated in the upper 15-cm layer of natural soils or in Ap horizon of plagued soils, thus vertical migration of radionuclide is very slow in spite of ∼30 years after Chernobyl accident. But it may by considerable

  15. Malaysia and forced migration

    OpenAIRE

    Arzura Idris

    2012-01-01

    This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysi...

  16. Unemployment, migration, and growth

    OpenAIRE

    Valerie R. Bencivenga; Bruce D. Smith

    1995-01-01

    Economic development is typically accompanied by a very pronounced migration of labor from rural to urban employment. This migration, in turn, is often associated with large scale urban underemployment. Both factors appear to play a very prominent role in the process of development. We consider a model in which rural-urban migration and urban underemployment are integrated into an otherwise conventional neoclassical growth model. Unemployment arises not from any exogenous rigidities, but from...

  17. TYPES OF MODERN MIGRATION

    OpenAIRE

    KAITMAZOVA KARINA RUSLANOVNA; CABERTI ALINA NODAROVNA

    2016-01-01

    The detailed classification of migration is analyzed, also a conclusion is drawn according to the fact that migration contributes to the development of the population of countries and regions, appearing to be a driving force and an important factor of globalization in the XXI century. Russia, also as other countries, strongly depends on migration: future of the Russian Federation depends on the fact how socially-spiritual community of Russian people will change, and also culture and values of...

  18. Many Faces of Migrations

    OpenAIRE

    Milica Antić Gaber; Marko Krevs

    2013-01-01

    Temporary or permanent, local or international, voluntary or forced, legal or illegal, registered or unregistered migrations of individuals, whole communities or individual groups are an important factor in constructing and modifying (modern) societies. The extent of international migrations is truly immense. At the time of the preparation of this publication more than 200 million people have been involved in migrations in a single year according to the United Nations. Furthermore, three time...

  19. Regional Redistribution and Migration

    DEFF Research Database (Denmark)

    Manasse, Paolo; Schultz, Christian

    We study a model with free migration between a rich and a poor region. Since there is congestion, the rich region has an incentive to give the poor region a transfer in order to reduce immigration. Faced with free migration, the rich region voluntarily chooses a transfer, which turns out to be...... equal to that a social planner would choose. Provided migration occurs in equilibrium, this conclusion holds even in the presence of moderate mobility costs. However, large migration costs will lead to suboptimal transfers in the market solution...

  20. The density variance - Mach number relation in isothermal and non-isothermal adiabatic turbulence

    CERN Document Server

    Nolan, Chris A; Sutherland, Ralph S

    2015-01-01

    The density variance - Mach number relation of the turbulent interstellar medium is relevant for theoretical models of the star formation rate, efficiency, and the initial mass function of stars. Here we use high-resolution hydrodynamical simulations with grid resolutions of up to 1024^3 cells to model compressible turbulence in a regime similar to the observed interstellar medium. We use Fyris Alpha, a shock-capturing code employing a high-order Godunov scheme to track large density variations induced by shocks. We investigate the robustness of the standard relation between the logarithmic density variance (sigma_s^2) and the sonic Mach number (M) of isothermal interstellar turbulence, in the non-isothermal regime. Specifically, we test ideal gases with diatomic molecular (gamma = 7/5) and monatomic (gamma = 5/3) adiabatic indices. A periodic cube of gas is stirred with purely solenoidal forcing at low wavenumbers, leading to a fully-developed turbulent medium. We find that as the gas heats in adiabatic comp...

  1. From Immigration to Migration Systems: New Concepts in Migration History.

    Science.gov (United States)

    Hoerder, Dirk

    1999-01-01

    Describes the characteristics of migration systems where two or more societies are connected through migration patterns. Identifies the four major migration systems that populated North America. Reviews the literature in relation to migration systems and discusses autobiographical accounts of migration. Provides an extensive bibliography. (CMK)

  2. The Calculation of Adsorption Isotherms from Chromatographic Peak Shapes

    Science.gov (United States)

    Neumann, M. G.

    1976-01-01

    Discusses the relationship between adsorption isotherms and elution peak shapes in gas chromatography, and describes a laboratory experiment which involves the adsorption of hexane, cyclohexane, and benzene on alumina at different temperatures. (MLH)

  3. Refrigeration Carnot-type cycle based on isothermal vapour compression

    Energy Technology Data Exchange (ETDEWEB)

    Meunier, F. [Laboratoire du Froid EA 21, Cnam-IFFI, 292 rue Saint-Martin (France)

    2006-01-01

    A refrigeration Carnot-type cycle based on isothermal compression and two reversible expansions is proposed. Although ideal, this cycle is close to a realistic one which could be designed with existing hardware. (author)

  4. Improved Isotherm Data for Adsorption of Methane on Activated Carbons

    KAUST Repository

    Loh, Wai Soong

    2010-08-12

    This article presents the adsorption isotherms of methane onto two different types of activated carbons, namely, Maxsorb III and ACF (A-20) at temperatures from (5 to 75) °C and pressures up to 2.5 MPa. The volumetric technique has been employed to measure the adsorption isotherms. The experimental results presented herein demonstrate the improved accuracy of the uptake values compared with previous measurement techniques for similar adsorbate-adsorbent combinations. The results are analyzed with various adsorption isotherm models. The heat of adsorption, which is concentration and temperature dependent, has been calculated from the measured isotherm data. Henry\\'s law coefficients for these adsorbent-methane pairs are also evaluated at various temperatures. © 2010 American Chemical Society.

  5. Equilibrium isotherm and kinetics modeling of U(VI) adsorption by natural soil systems

    International Nuclear Information System (INIS)

    This research examined the adsorption capability of natural soils of different origin for U(VI) at soil-water interface and the mechanism involved. Adsorption kinetics study indicates that adsorption followed the pseudo-second order kinetics irrespective of soil types and was not solely controlled by the diffusion step rather surface complexation and ion-exchange plays major role. Study of adsorption isotherms indicates adsorption involves chemisorption and soil with high Fe and Mn content better fit to Langmuir model. The study provides a better insight for site selection for radioactive waste (uranium) disposal facilities as well as soil suitable for back fill or permeable reactive barrier to inhibit migration of U(VI). (author)

  6. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    OpenAIRE

    Carlos Carvalho Engler-Pinto Júnior; Dirceu Spinelli

    2014-01-01

    Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF) and thermomechanical fatigue (TMF). Test ...

  7. A Study of Isothermal Curing of PMI Using DMA

    OpenAIRE

    Jing Zhang; Rui Ye; Jun Zou; Jijun Tang; Hongliang Wang

    2015-01-01

    The isothermal curing of polymethacrylimide (PMI) is studied through the use of dynamic mechanical analysis (DMA). Based on the growth rate of measured dynamic mechanical property, the relative conversion is defined to investigate the evolution of storage modulus E′ at different curing temperatures. Hsich’s nonequilibrium thermodynamic fluctuation theory, Avrami equation, and isoconversional methods are used to analyze isothermal cure kinetics of PMI. The results show that there are different...

  8. Non-isothermal Crystallization Kinetics of Poly(L-lactide)

    OpenAIRE

    Li, Suming

    2010-01-01

    International audience The non-isothermal crystallization kinetics of poly(L-lactide) (PLLA) in comparison with a polylactide stereocopolymer (PLA98) containing 98% L-lactyl and 2% D-lactyl units were investigated using differential scanning calorimetry to examine the effect of the configurational structure. Avrami, Ozawa and Liu models were applied to describe the crystallization process. The Avrami analysis exhibited two stages in non-isothermal crystallization, while the Ozawa and Liu m...

  9. On The Strategies Towards Isothermal Gas Compression And Expansion

    OpenAIRE

    Heidari, Mahbod; Lemofouet, Sylvain; Rufer, Alfred

    2014-01-01

    Isothermal compression/expansion is regarded as the most promising process in many applications and many researchers and inventors have tried different methods to achieve this goal. The current article first studies the gradual roadmap from adiabatic towards isothermal process from thermodynamics and heat transfer point of view. Different strategies are investigated to achieve this goal by evaluating different possibilities; the bottleneck of the problem is then identified and then increment ...

  10. Sampling the isothermal-isobaric ensemble by Langevin dynamics

    OpenAIRE

    Gao, Xingyu; Fang, Jun; Wang, Han

    2016-01-01

    We present a new method of conducting molecular dynamics simulation in isothermal-isobaric ensemble based on Langevin equations of motion. The stochastic coupling to all particle and cell degrees of freedoms is introduced in a correct way, in the sense that the stationary configurational distribution is proved to be in consistent with that of the isothermal-isobaric ensemble. In order to apply the proposed method in computer simulations, a second order symmetric numerical integration scheme i...

  11. Isothermal Calorimetry for Biological Applications in Food Science and Technology

    OpenAIRE

    Wadsö, Lars; Gomez, Federico

    2009-01-01

    All physical, chemical and biological processes produce heat and isothermal calorimetry is a general measurement technique to study all kinds of processes by the heat they produce. This paper gives several examples of studies of biological processes in the food area using isothermal calorimetry. It is for example shown how different unit operations influence respiration of vegetable tissue, how the kinetics of a fermentation process can be studied, and how spoilage processes can be followed f...

  12. High Temperature Behavior of Isothermally Compressed M50 Steel

    Institute of Scientific and Technical Information of China (English)

    Li-xing SUN; Miao-quan LI

    2015-01-01

    The isothermal compression of M50 steel is carried out on a Gleeble-3500 thermo-mechanical simulator in temperature range of 1 223—1 423 K and strain rates range of 10—70 s—1. The results show that the carbides play a signiifcant role in the lfow be-havior and microstructure evolution during isothermal compression of M50 steel. The average apparent activation energy for defor-mation in isothermal compression of M50 steel is (281.1±42.6) kJ∙mol—1 at the strains of 0.4—0.8. The dynamic recrystallization of austenite grains occurs in isothermal compression of M50 steel at 1 363 K and 1 393 K, enhancing with the increase of strain rate and/or strain. The volume fraction of the carbides decreases with the increase of deformation temperature during isothermal com-pression of M50 steel and the ifne carbides inhibit the dynamic recrystallization of austenite grain. With the occurrence of dynamic recrystallization, the austenite grains are reifned, leading to a minor increase in the lfow stress and apparent activation energy for deformation in isothermal compression of M50 steel. The austenite grains begin to coarsen at 1 423 K and dynamic recrystalliza-tion is limited. Hot working of M50 steel should not be performed above 1 393 K in order to achieve good workability.

  13. An Isothermal Steam Expander for an Industrial Steam Supplying System

    Directory of Open Access Journals (Sweden)

    Chen-Kuang Lin

    2015-01-01

    Full Text Available Steam is an essential medium used in the industrial process. To ensure steam quality, small and middle scale boilers are often adopted. However, because a higher steam pressure (compared to the necessary steam pressure is generated, the boiler’s steam pressure will be reduced via a pressure regulator before the steam is directed through the process. Unfortunately, pressure is somewhat wasted during the reducing process. Therefore, in order to promote energy efficiency, a pressure regulator is replaced by a steam expander. With this steam expander, the pressure will be transformed into mechanical energy and extracted during the expansion process. A new type of isothermal steam expander for an industrial steam supplying system will be presented in the paper. The isothermal steam expander will improve the energy efficiency of a traditional steam expander by replacing the isentropic process with an isothermal expansion process. With this, steam condensation will decrease, energy will increase, and steam quality will be improved. Moreover, the mathematical model of the isothermal steam expander will be established by using the Schmidt theory, the same principle used to analyze Stirling engines. Consequently, by verifying the correctness of the theoretical model for the isothermal steam expander using experimental data, a prototype of 100 c.c. isothermal steam expander is constructed.

  14. Numerical studies of pulsating buoyant plume in isothermal and non isothermal situations

    International Nuclear Information System (INIS)

    A computational study has been carried out for predicting the behaviour of buoyant plume in isothermal and non isothermal configuration. General simulation objectives of any buoyant flow simulation are macroscopic in nature and deals with the grass data in respect of buoyancy induced scalar transport. However, the accuracy of predicting such macroscopic parameters is a strong function of several other microscopic parameters which govern the overall macroscopic behaviour. Some of the microscopic parameters for analysis could be buoyancy induced stable/unstable flows, relative plume behaviour, baroclinic velocity distribution etc. Only the CFD based flow modelling approach is capable of calculating several of these aspects. LES based modelling scores over the conventional RANS based computational modelling. The primary objective of the present study was to model buoyant plume simulation of different types in order to explore the details regarding plume and flow structure, instabilities and puffing behaviour. One of the influencing parameters on the overall plume behaviour is the buoyancy resolution index i.e. fineness of chosen grid in relation to the buoyancy intensity and other hydrodynamic parameters. The grid sensitivity studies have been carried out to find out the optimum value grid size by way of buoyant pool fire simulations. Comparative simulation has also been made for a square and round pool fire and it was found that for engineering simulations equivalent area square pool modeling is sufficient. Using the optimum value of grid size and square pool shape simulations have been carried out for different value of fire intensity. The flame puffing frequency as calculated by the reported correlation was compared against the computationally observed puffing frequency and the agreement was generally found to be excellent. Besides these results the comparisons of predicted peak flames temperatures data for various case studies with the available experimental data

  15. Migration, klima og sundhed

    DEFF Research Database (Denmark)

    Tellier, Siri; Carballo, Manuel

    2009-01-01

    Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which...

  16. Migration to Windows NT.

    Science.gov (United States)

    Doles, Daniel T.

    In the constantly changing world of technology, migration is not only inevitable but many times necessary for survival, especially when the end result is simplicity for both users and IT support staff. This paper describes the migration at Franklin College (Indiana). It discusses the reasons for selecting Windows NT, the steps taken to complete…

  17. International Migration of Couples

    DEFF Research Database (Denmark)

    Munk, Martin D.; Junge, Martin; Poutvaara, Panu

    2016-01-01

    We develop a theoretical model regarding the migration of dual-earner couples and test it in the context of international migration. Our model predicts that the probability that a couple emigrates increases with the income of the primary earner, whereas the income of the secondary earner may affect...

  18. Migration, Narration, Identity

    DEFF Research Database (Denmark)

    Leese, Peter

    (co-editor with Carly McLaughlin and Wladyslaw Witalisz) This book presents articles resulting from joint research on the representations of migration conducted in connection with the Erasmus Intensive Programme entitled «Migration and Narration» taught to groups of international students over...

  19. Migrating Art History

    DEFF Research Database (Denmark)

    Ørum, Tania

    2012-01-01

    Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0.......Review of Hiroko Ikegami, The Great Migrator. Robert Rauschenberg and the Global Rise of American Art. Cambridge Mass., The MIT Press, 2010. 277 pages. ISBN 978-0-262-01425-0....

  20. Migrating for a Profession

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2015-01-01

    Youths from the Global South migrating for further education often face various forms of discrimination. This Caribbean case study discusses how conditions in the home country can provide a foundation for educational migration that helps the migrants overcome such obstacles and even develop a...

  1. Samtidskunst og migration

    DEFF Research Database (Denmark)

    Petersen, Anne Ring

    2010-01-01

    "Samtidskunst og migration. En oversigt over faglitteraturen" er en forskningsoversigt der gør status over hvad der hidtil er skrevet inden for det kunsthistoriske område om vor tids billedkunst og migration som politisk, socialt og kulturelt fænomen, primært i forbindelse med immigration til...

  2. Migration and Rural Development

    OpenAIRE

    Robert E. B. Lucas

    2007-01-01

    The paper summarizes the key routes through which internal and international migration impact rural development and some of the evidence pertaining to these effects in low income countries. It concludes that, although the study of migration impacts on rural economies has come a long way from the early dual theories of development, some of the potentially more important aspects remain to be investigated systematically.

  3. Environmental change and migration

    Czech Academy of Sciences Publication Activity Database

    Stojanov, Robert

    Santa Barbara, Calif : Praeger, 2012 - (Segal, U.; Elliot, D.), s. 55-89 ISBN 978-0-313-37807-2 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional research plan: CEZ:AV0Z60870520 Keywords : migration processes * environmental change * climate change * environmental migrants * human migration Subject RIV: AO - Sociology, Demography

  4. Isothermal and non-isothermal crystallization kinetics of PVA + ionic liquid [BDMIM][BF4]-based polymeric films

    Science.gov (United States)

    Saroj, A. L.; Chaurasia, S. K.; Kataria, Shalu; Singh, R. K.

    2016-06-01

    The effect of ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM][BF4], on crystallization behavior of poly(vinyl alcohol) (PVA) has been studied by isothermal and non-isothermal differential scanning calorimetry techniques. The PVA + IL based polymer electrolyte films have been prepared using solution casting technique. To describe the isothermal and non-isothermal crystallization kinetics, several kinetic equations have been employed on PVA + IL based films. There is strong dependence of the peak crystallization temperature (Tc), relative degree of crystallity (Xt), half-time of crystallization (t1/2), crystallization rate constants (Avrami Kt and Tobin AT), and Avrami (n) and Tobin (nT) exponents on the cooling rate and IL loading.

  5. World Migration Degree Global migration flows in directed networks

    CERN Document Server

    Porat, Idan

    2015-01-01

    In this article we analyze the global flow of migrants from 206 source countries to 145 destination countries (2006-2010) and focus on the differences in the migration network pattern between destination and source counters as represented by its degree and weight distribution. Degree represents the connectivity of a country to the global migration network, and plays an important role in defining migration processes and characteristics. Global analysis of migration degree distribution offers a strong potential contribution to understanding of migration as a global phenomenon. In regard to immigration, we found that it is possible to classify destination countries into three classes: global migration hubs with high connectivity and high migration rate; local migration hubs with low connectivity and high migration rate; and local migration hubs with opposite strategy of high connectivity and low migration rate. The different migration strategies of destination countries are emerging from similar and homogenies p...

  6. Malaysia and forced migration

    Directory of Open Access Journals (Sweden)

    Arzura Idris

    2012-06-01

    Full Text Available This paper analyzes the phenomenon of “forced migration” in Malaysia. It examines the nature of forced migration, the challenges faced by Malaysia, the policy responses and their impact on the country and upon the forced migrants. It considers forced migration as an event hosting multifaceted issues related and relevant to forced migrants and suggests that Malaysia has been preoccupied with the issue of forced migration movements. This is largely seen in various responses invoked from Malaysia due to “south-south forced migration movements.” These responses are, however, inadequate in terms of commitment to the international refugee regime. While Malaysia did respond to economic and migration challenges, the paper asserts that such efforts are futile if she ignores issues critical to forced migrants.

  7. Migration of health workers.

    Science.gov (United States)

    Buchan, James

    2008-01-01

    The discussion and debate stimulated by these papers focused across a range of issues but there were four main areas of questioning: "measuring" and monitoring migration (issues related to comparability, completeness and accuracy of data sets on human resources); the impact of migration of health workers on health systems; the motivations of individual health workers to migrate (the "push" and "pull" factors) and the effect of policies designed either to reduce migration (e.g "self ufficiency") or to stimulate it (e.g active international recruitment). It was recognised that there was a critical need to examine migratory flows within the broader context of all health care labour market dynamics within a country, that increasing migration of health workers was an inevitable consequence of globalisation, and that there was a critical need to improve monitoring so as to better inform policy formulation and policy testing in this area. PMID:18561695

  8. Analysis of the effect of hydraulic parameters on radionuclide migration in an unsaturated zone

    International Nuclear Information System (INIS)

    A One-Dimensional Water Flow and Contaminant Transport in Unsaturated Zone (FTUNS) code has been developed in order to interpret radionuclide migration in an unsaturated zone. The pore-size distribution index (n) and the inverse of the air-entry value (α) for an unsaturated zone were measured by KS M ISO 11275 method. The hydraulic parameters of the unsaturated soil are investigated by using soil from around a nuclear facility in Korea. The effect of hydraulic parameters on radionuclide migration in an unsaturated zone has been analyzed. The higher the value of the n-factor, the more the cobalt concentration was condensed. The larger the value of α-factor, the faster the migration of cobalt was and the more aggregative the cobalt concentration was. Also, it was found that an effect on contaminant migration due to the pore-size distribution index (n) and the inverse of the air-entry value (α) was minute. Meanwhile, migrations of cobalt and cesium a rein inverse proportion to the Freundich isotherm coefficient. That is to say, the migration velocity of cobalt was about 8.35times that of cesium. It was conclusively demonstrated that the Freundich isotherm coefficient was the most important factor for contaminant migration

  9. Isothermal and non-isothermal cure of a tri-functional epoxy resin (TGAP): A stochastic TMDSC study

    International Nuclear Information System (INIS)

    Highlights: ► First evaluation of Tg of tri-functional epoxy resin TGAP by DSC. ► Clearly shows advantages of TOPEM for isothermal and non-isothermal cure analysis. ► Evidence of highly non-linear enthalpy relaxation in partially cured TGAP system. - Abstract: The isothermal cure of a highly reactive tri-functional epoxy resin, tri-glycidyl para-amino phenol (TGAP), with diamino diphenyl sulphone (DDS), at two different cure temperatures Tc has been studied by both conventional differential scanning calorimetry (DSC) and by a stochastic temperature modulated DSC technique, TOPEM. From a series of isothermal cure experiments for increasing cure times, the glass transition temperature Tg as a function of isothermal cure time is determined by conventional DSC from a second (non-isothermal) scan, and the vitrification time tv is obtained as the time at which Tg = Tc. In parallel, TOPEM experiments at the same Tc lead directly to the determination of tv from the sigmoidal change in the quasi-static heat capacity. It is not possible to identify the glass transition temperature of the fully cured system, Tg∞, in a third scan by conventional DSC. In contrast, with TOPEM a second (non-isothermal) scan at 2 K/min after the isothermal cure gives rise to three separate transitions: devitrification of the partially cured and vitrified material; almost immediate vitrification as the Tg of the system again rises; finally another devitrification, at a temperature approximating closely to Tg∞. Thus with TOPEM it is possible to obtain a calorimetric measure of the glass transition temperature of this fully cured system.

  10. Caesium 137: Properties and biological effects resulting of an internal contamination;Cesium 137: proprietes et effets biologiques apres contamination interne

    Energy Technology Data Exchange (ETDEWEB)

    Lestaevel, P.; Racine, R.; Bensoussan, H.; Rouas, C.; Gueguen, Y.; Dublineau, I.; Bertho, J.M.; Gourmelon, P.; Jourdain, J.R.; Souidi, M. [Institut de Radioprotection et de Surete Nucleaire, IRSN, laboratoire de radiotoxicologie experimentale, direction de la radioprotection de l' homme, 92 - Fontenay-aux-Roses (France)

    2010-02-15

    Caesium-137 ({sup 137}Cs) is a radionuclide present in the environment mainly as the result of the atmospheric nuclear weapons testing and accidents arising in nuclear power plants like the Chernobyl accident in 1986. Nowadays, the health consequences resulting from a chronic exposure to this radionuclide remain unknown. After absorption, the caesium is distributed relatively homogeneously within the body, with a more important load in children than in adults. The toxicity of {sup 137}Cs is mainly due to its radiological properties. A high dose of {sup 137}Cs is responsible for a medullar dystrophy, disorders of the reproductive function, and effects on liver and renal functions. Disorders of bone mineralization and brain damages were also described in human beings. At lowest dose, {sup 137}Cs induces disturbances of wakefulness-sleep cycle, but not accompanied with behavioural disorders. The cardiovascular system was also perturbed. Biological effects of {sup 137}Cs on the metabolisms of the vitamin D, cholesterol and steroid hormones were described, but do not lead to clinical symptoms. In human beings, {sup 137}Cs leads to an immune deficiency, congenital and foetal deformations, an increased of thyroid cancer, as well as neurological disorders. It seems that children are more sensitive to the toxic effects of caesium than the adults. At present, the only effective treatment for the decorporation of the ingested {sup 137}Cs is the Prussian Blue (Radiogardase). The use of pectin to de-corporate the ingested {sup 137}Cs, in children notably, is sometimes proposed, but its administration still remains an open question. To conclude, the available scientific data suggest that {sup 137}Cs could affect a number of physiological and metabolic functions and consequently, could participate in the health risks associated to the presence of other contaminants in the environment. (authors)

  11. A new approach to predicting environmental transfer of radionuclides to wildlife: A demonstration for freshwater fish and caesium

    International Nuclear Information System (INIS)

    The application of the concentration ratio (CR) to predict radionuclide activity concentrations in wildlife from those in soil or water has become the widely accepted approach for environmental assessments. Recently both the ICRP and IAEA have produced compilations of CR values for application in environmental assessment. However, the CR approach has many limitations, most notably, that the transfer of most radionuclides is largely determined by site-specific factors (e.g. water or soil chemistry). Furthermore, there are few, if any, CR values for many radionuclide-organism combinations. In this paper, we propose an alternative approach and, as an example, demonstrate and test this for caesium and freshwater fish. Using a Residual Maximum Likelihood (REML) mixed-model regression we analysed a dataset comprising 597 entries for 53 freshwater fish species from 67 sites. The REML analysis generated a mean value for each species on a common scale after REML adjustment taking account of the effect of the inter-site variation. Using an independent dataset, we subsequently test the hypothesis that the REML model outputs can be used to predict radionuclide, in this case radiocaesium, activity concentrations in unknown species from the results of a species which has been sampled at a specific site. The outputs of the REML analysis accurately predicted 137Cs activity concentrations in different species of fish from 27 Finnish lakes; these data had not been used in our initial analyses. We recommend that this alternative approach be further investigated for other radionuclides and ecosystems. - Highlights: • An alternative approach to estimating radionuclide transfer to wildlife is presented. • Analysed a dataset comprising 53 freshwater fish species collected from 67 sites. • Residual Maximum Likelihood mixed model regression is used. • Model output takes account of the effect of inter-site variation. • Successfully predicted 137Cs concentrations in different fish

  12. Desorption behaviour of artificial radionuclides sorbed on to estuarine silt: (1) Caesium-137 and ruthenium-106, (2) Zirconium-95 and niobium-95

    International Nuclear Information System (INIS)

    A series of desorption tests was carried out on silt contaminated with radioactive waste from the Sellafield (formerly Windscale) fuel reprocessing plant. The aim of the desorptions was to attempt to elucidate the chemical form in which certain radionuclides were held by the sediments. The first part of the study indicated that caesium was held, in the main, on inaccessible ion-exchange sites and that ruthenium appeared to be partially adsorbed and partially held by anion-exchange sites. The second part of the study indicated that zirconium and niobium were sorbed chemically or physically in the form of complex hydrous oxides. (author)

  13. Spectral anomalies of the effect of light-induced drift of caesium atoms caused by the velocity dependence of transport collision frequencies

    International Nuclear Information System (INIS)

    The spectral features of the light-induced drift (LID) velocity of caesium atoms in inert buffer gases are studied theoretically. A strong temperature dependence of the spectral LID line shape of Cs atoms in Ar or Kr atmosphere in the vicinity of T ∼ 1000 K is predicted. It is shown that the anomalous LID of Cs atoms in binary buffer mixtures of two different inert gases can be observed at virtually any (including ambient) temperature, depending on the content of the components in these mixtures. The results obtained make it possible to precisely test the interatomic interaction potentials in the experiments on the anomalous LID. (quantum optics)

  14. Poly[(μ6-4-amino-3,5,6-trichloro­pyridine-2-carboxyl­ato)aqua­caesium

    OpenAIRE

    Smith, Graham

    2012-01-01

    In the structure of the title complex, [Cs(C6H2Cl3N2O2)(H2O)] n , the caesium salt of the commercial herbicide picloram, the Cs+ cation lies on a crystallographic mirror plane, which also contains the coordinating water mol­ecule and all non-H atoms of the 4-amino-3,5,6-trichloro­picolinate anion except the carboxyl­ate O-atom donors. The irregular CsCl4O5 coordination polyhedron comprises chlorine donors from the ortho-related ring substituents of the picloramate ligand in a bidentate chelat...

  15. Migration, Skills and Productivity

    OpenAIRE

    Robert Hierländer; Peter Huber; Anna Iara; Michael Landesmann; Klaus Nowotny; Mary O'Mahony; Fei Peng; Catherine Robinson; Robert Stehrer

    2010-01-01

    The literature on international migration has repeatedly emphasized that the extent and structure of migration has an important impact on the competitiveness of regions and countries. This report provides an overview of the extent and the potential effects of high-skill migration to the EU27. It shows how many high-skilled migrants live in the EU, where these migrants come from, and how the European Union is positioned in the international competition for talent. Second, we examine how high-s...

  16. Single time point isothermal drug stability experiments at constant humidity.

    Science.gov (United States)

    Tao, Jian-Lin; Zhan, Xian-Cheng; Li, Lin-Li; Lin, Bing; Jiang, Lu

    2009-03-01

    A single time point isothermal drug stability experiments at constant humidity is introduced. In the new method, kinetic parameters related to both moisture and temperature were obtained by a single pair of experiments: these related to moisture by one with a group of testing humidities and a fixed temperature, those related to temperature by the other with a group of testing temperatures and a constant humidity. By a simulation, the estimates for the kinetic parameters (E(a), m, A) obtained by the proposed method and the reported programmed humidifying and heating method were statistically evaluated and were compared with those obtained by the isothermal measurements at constant humidity. Results indicated that under the same experimental conditions, the estimates obtained by the proposed method were significantly more precise than those obtained by the reported programmed humidifying and heating method. The estimates obtained by the isothermal method at constant humidity were somewhat more precise than those obtained by the proposed method. However, the experimental period needed by the isothermal method at constant humidity was greatly longer than that needed by the proposed method. The stability of dicloxacillin sodium, as a solid state model, was investigated by the single time point isothermal drug stability experiments at constant humidity. The results indicated that the kinetic parameters obtained by the proposed method were comparable to those from the reported. PMID:19252391

  17. Binding Isotherms and Time Courses Readily from Magnetic Resonance.

    Science.gov (United States)

    Xu, Jia; Van Doren, Steven R

    2016-08-16

    Evidence is presented that binding isotherms, simple or biphasic, can be extracted directly from noninterpreted, complex 2D NMR spectra using principal component analysis (PCA) to reveal the largest trend(s) across the series. This approach renders peak picking unnecessary for tracking population changes. In 1:1 binding, the first principal component captures the binding isotherm from NMR-detected titrations in fast, slow, and even intermediate and mixed exchange regimes, as illustrated for phospholigand associations with proteins. Although the sigmoidal shifts and line broadening of intermediate exchange distorts binding isotherms constructed conventionally, applying PCA directly to these spectra along with Pareto scaling overcomes the distortion. Applying PCA to time-domain NMR data also yields binding isotherms from titrations in fast or slow exchange. The algorithm readily extracts from magnetic resonance imaging movie time courses such as breathing and heart rate in chest imaging. Similarly, two-step binding processes detected by NMR are easily captured by principal components 1 and 2. PCA obviates the customary focus on specific peaks or regions of images. Applying it directly to a series of complex data will easily delineate binding isotherms, equilibrium shifts, and time courses of reactions or fluctuations. PMID:27458657

  18. Migration og etnicitet

    DEFF Research Database (Denmark)

    Christiansen, Connie Carøe

    2004-01-01

    Migration og etnicitet er aktuelle og forbundne fænomener, idet migration øger berøringsfladerne mellem befolkningsgrupper. Etniciteter formes i takt med at grænser drages imellem disse grupper. Imod moderniserings-teoriernes forventning forsvandt etnicitet ikke som en traditionel eller oprindelig...... måde at skabe tilhørsforhold på; globalt set fremstår vor tid istedet som en "migrationens tidsalder", der tilsyneladende også er en tidsalder, hvor kulturelle særtræk, i form af etnicitet, udgør vigtige linjer, hvorefter grupper skilller sig ud fra hinanden. Både migration og etnicitet bringer fokus...... den finder sted i modtagerlandet, men nyere perspektiver på migration, som begreber om medborgerskab, transnationalisme og diaspora er eksponenter for, søger udover den nationalstatslige ramme og inddrager konsekvenserne af migrationen for afsenderlande....

  19. Kinetics of the chrysotile and brucite dehydroxylation reaction: a combined non-isothermal/isothermal thermogravimetric analysis and high-temperature X-ray powder diffraction study

    OpenAIRE

    Trittschack, Roy; Grobéty, Bernard; Brodard, Pierre

    2014-01-01

    The dehydroxylation reactions of chrysotile Mg₃Si₂O₅(OH)₄ and brucite Mg(OH)₂ were studied under inert nitrogen atmosphere using isothermal and non-isothermal approaches. The brucite decomposition was additionally studied under CO₂ in order to check the influence of a competing dehydroxylation/carbonation/decarbonisation reaction on the reaction kinetics. Isothermal experiments were conducted using in situ high-temperature X-ray powder diffraction, whereas non-isothermal experiments were perf...

  20. Indonesia's migration transition.

    Science.gov (United States)

    Hugo, G

    1995-01-01

    This article describes population movements in Indonesia in the context of rapid and marked social and economic change. Foreign investment in Indonesia is increasing, and global mass media is available to many households. Agriculture is being commercialized, and structural shifts are occurring in the economy. Educational levels are increasing, and women's role and status are shifting. Population migration has increased over the decades, both short and long distance, permanent and temporary, legal and illegal, and migration to and between urban areas. This article focuses specifically on rural-to-urban migration and international migration. Population settlements are dense in the agriculturally rich inner areas of Java, Bali, and Madura. Although the rate of growth of the gross domestic product was 6.8% annually during 1969-94, the World Bank ranked Indonesia as a low-income economy in 1992 because of the large population size. Income per capita is US $670. Indonesia is becoming a large exporter of labor to the Middle East, particularly women. The predominance of women as overseas contract workers is changing women's role and status in the family and is controversial due to the cases of mistreatment. Malaysia's high economic growth rate of over 8% per year means an additional 1.3 million foreign workers and technicians are needed. During the 1980s urban growth increased at a very rapid rate. Urban growth tended to occur along corridors and major transportation routes around urban areas. It is posited that most of the urban growth is due to rural-to-urban migration. Data limitations prevent an exact determination of the extent of rural-to-urban migration. More women are estimated to be involved in movements to cities during the 1980s compared to the 1970s. Recruiters and middlemen have played an important role in rural-to-urban migration and international migration. PMID:12347370

  1. Labour Migration in Europe

    OpenAIRE

    Menz, Georg; Caviedes, Alexander

    2010-01-01

    Economic migration has been rediscovered by governments across Europe. Highly skilled migrants are actively solicited, irregular migrants are being offered amnesties, and East-West migration is welcomed by business and employer associations. However, this is a highly politicized and contested policy domain. This timely collection of cutting-edge research explores and examines the new realities of economic immigration to Europe. The thematic focus rests on new trends and developments, includin...

  2. Migration of Interplanetary Dust

    OpenAIRE

    Ipatov, S. I.; Mather, J. C.; Taylor, P.A.

    2003-01-01

    We numerically investigate the migration of dust particles with initial orbits close to those of the numbered asteroids, observed trans-Neptunian objects, and Comet Encke. The fraction of silicate asteroidal particles that collided with the Earth during their lifetime varied from 1.1% for 100 micron particles to 0.008% for 1 micron particles. Almost all asteroidal particles with diameter d>4 microns collided with the Sun. The peaks in the migrating asteroidal dust particles' semi-major axis d...

  3. Remittances and Return Migration

    OpenAIRE

    Collier, William J.; Piracha, Matloob E; Randozza, Teresa

    2011-01-01

    This paper utilises survey data of return migrants to analyse the determinants of remittances sent while the migrants were abroad. We approach our research question from the perspective of three sending countries in the Maghreb, namely Algeria, Morocco and Tunisia. We investigate the remittance behaviour using the migrants’ conditions before migration as well as during the migration experience. Using a two-part model, we show that the decision to remit and the amount remitted depend on a comb...

  4. Migration and Culture

    OpenAIRE

    Epstein, Gil S.; Ira N. Gang

    2010-01-01

    Culture is not new to the study of migration. It has lurked beneath the surface for some time, occasionally protruding openly into the discussion, usually under some pseudonym. The authors bring culture into the open. They are concerned with how culture manifests itself in the migration process for three groups of actors: the migrants, those remaining in the sending areas, and people already living in the recipient locations. The topics vary widely. What unites the authors is an understanding...

  5. EFFICIENCY OF PROTECTIVE MEASURES TO REDUCE INTERNAL DOSE FROM CAESIUM RADIONUCLIDES FOR THE INHABITANTS OF RADIOACTIVE CONTAMINATION AREA IN THE FIRST YEARS AFTER THE CHERNOBYL ACCIDENT

    Directory of Open Access Journals (Sweden)

    I. G. Travnikova

    2012-01-01

    Full Text Available In the paper, we use the data on the content of caesium radionuclides in foodstuffs and in Bryansk region adult inhabitant’s body, on their food ration and its changes during the first years after the Chernobyl accident, and on the measures to protect the population from internal exposure. We calculate dynamics of 137Cs intake in the body and its contents therein, while maintaining a traditional diet and while replacing food products for radiationfree ones. The results show that the actual 137Cs content in the body is usually below the one calculated on the basis of the food ration. It was found out that individual 137Cs contents in the body correlate with the rate of meat, dairy and natural food products consumption and with factors of protection from internal exposure. The efficiency of the protective measures to reduce the intake and the content of caesium radionuclides in the body of inhabitants, as well as the average effective dose in the first years after the accident has been quantitatively assessed.

  6. Determination of Differential Enthalpy and Isotherm by Adsorption Calorimetry

    Directory of Open Access Journals (Sweden)

    V. Garcia-Cuello

    2008-01-01

    Full Text Available An adsorption microcalorimeter for the simultaneous determination of the differential heat of adsorption and the adsorption isotherm for gas-solid systems are designed, built, and tested. For this purpose, a Calvet heat-conducting microcalorimeter is developed and is connected to a gas volumetric unit built in stainless steel to record adsorption isotherms. The microcalorimeter is electrically calibrated to establish its sensitivity and reproducibility, obtaining K=154.34±0.23 WV−1. The adsorption microcalorimeter is used to obtain adsorption isotherms and the corresponding differential heats for the adsorption of CO2 on a reference solid, such as a NaZSM-5 type zeolite. Results for the behavior of this system are compared with those obtained with commercial equipment and with other studies in the literature.

  7. Non-isothermal Moisture Transport Through Insulation Materials

    DEFF Research Database (Denmark)

    Peuhkuri, Ruut Hannele; Rode, Carsten; Hansen, Kurt Kielsgaard

    2008-01-01

    An experimental investigation was conducted in order to draw some conclusions on the magnitude of moisture transport due to temperature gradient on a range of porous light-weight building materials. A special constructed non-isothermal set-up allowed the creation of a temperature gradient of 10K...... and given humidity gradient over the sample. The resulting moisture ux as well as the hygrothermal states around and within the material were monitored. The hypothesis of relative humidity being a driving force for non-isothermal moisture transport already in the hygroscopic range could not be......, diverging conclusions and therefore the question about existence of the type of transport forms driven by the non-isothermal effects remains open. Rather surprisingly, all the materials, including the almost non-hygroscopic materials (e.g. rock wool) and very hygroscopic materials (e.g. cellulose insulation...

  8. ORBITAL MIGRATION OF INTERACTING LOW-MASS PLANETS IN EVOLUTIONARY RADIATIVE TURBULENT MODELS

    International Nuclear Information System (INIS)

    The torques exerted by a locally isothermal disk on an embedded planet lead to rapid inward migration. Recent work has shown that modeling the thermodynamics without the assumption of local isothermality reveals regions where the net torque on an embedded planet is positive, leading to outward migration of the planet. When a region with negative torque lies directly exterior to this, planets in the inner region migrate outward and planets in the outer region migrate inward, converging where the torque is zero. We incorporate the torques from an evolving non-isothermal disk into an N-body simulation to examine the behavior of planets or planetary embryos interacting in the convergence zone. We find that mutual interactions do not eject objects from the convergence zone. Small numbers of objects in a laminar disk settle into near resonant orbits that remain stable over the 10 Myr periods that we examine. However, either or both increasing the number of planets or including a correlated, stochastic force to represent turbulence drives orbit crossings and mergers in the convergence zone. These processes can build gas giant cores with masses of order 10 Earth masses from sub-Earth mass embryos in 2-3 Myr.

  9. Return Migration, Wage Differentials, and the Optimal Migration Duration

    OpenAIRE

    Dustmann, Christian

    2001-01-01

    In simple static models, migration increases with the wage differential between host and home country. In a dynamic framework, and if migrations are temporary, the size of the migrant population in the host country depends also on the migration duration. This paper analyses optimal migration durations in a model which rationalises the decision of the migrant to return to his home country, despite persistently higher wages in the host country. The analysis shows that, if migrations are tempora...

  10. Adsorption isotherms of water on mica: redistribution and film growth.

    Science.gov (United States)

    Malani, Ateeque; Ayappa, K G

    2009-01-29

    Adsorption isotherms of water on muscovite mica are obtained using grand canonical Monte Carlo simulations over a wide range of relative vapor pressures, p/p(0) at 298 K. Three distinct stages are observed in the adsorption isotherm. A sharp rise in the water coverage occurs for 0 Clays Clay Miner. 2006 , 54 , 402 ), over the entire range of pressures investigated. Both SPC and extended simple point charge (SPC/E) water models were found to yield qualitatively similar adsorption and structural characteristics, with the SPC/E model predicting lower coverages than the SPC model for p/p(0) > 0.7. PMID:19123830

  11. Interpretation of Quasi-Isothermal Thermogravimetric Weight Curves

    DEFF Research Database (Denmark)

    Sørensen, Ole Toft

    1979-01-01

    Quasi-isothermal analysis (QIA) is a very useful technique. Compared to conventional non-isothermal thermogravimetry, close-lying reactions can easily be separated by use of this method and kinetic data can be obtained for each intermediate reaction in a single run. This paper discusses the shape...... of the weight and temperature curves expected in QIA for different controlling mechanisms, and a method is given for calculating the activation energies from these curves. As an example, the QIA curves obtained in thermal decomposition of ammonium-uranyl carbonate (AUC) are analysed and the kinetics of some...

  12. Construction of isotherms in solvent extraction of copper

    OpenAIRE

    Cvetkovski Vladimir B.; Conić Vesna T.; Vuković Milovan V.; Stojanovski Goran P.; Cvetkovska Milena V.

    2009-01-01

    The aim of this work is construction of equilibrium isotherms in solvent extraction. Technological parameters have been predicted for treatment of mine water by solvent extraction and electrowining. Two stages of extractions and one stage of stripping have been predicted for copper recovery by analyzing the equilibrium isotherms. The process was performed on mine water with 2,5 g/dm3 Cu2+, 3 g/dm Fe2+, pH 1,8, using 9 vol% LIX 984N in kerosene (organic solvent), with 95 and 98% stages efficie...

  13. Effects of Schwarzschild Geometry on Isothermal Plasma Wave Dispersion

    CERN Document Server

    Sharif, M

    2007-01-01

    The behavior of isothermal plasma waves has been analyzed near the Schwarzschild horizon. We consider a non-rotating background with non-magnetized and magnetized plasmas. The general relativistic magnetohydrodynamical equations for the Schwarzschild planar analogue spacetime with an isothermal state of the plasma are formulated. The perturbed form of these equations is linearized and Fourier analyzed by introducing simple harmonic waves. The determinant of these equations in each case leads to a complex dispersion relation, which gives complex values of the wave number. This has been used to discuss the nature of the waves and their characteristics near the horizon.

  14. MODERN MIGRATION POLICY OF RUSSIA

    Directory of Open Access Journals (Sweden)

    Kobylinsky S. V.

    2014-11-01

    Full Text Available Several peculiarities of the implementation of migration policy in the Russian Federation were considered in this article. We have shown main provisions on refugees and forced migrants from the Ukraine and labor migration. On the basis of the study we have suggested an improvement of migration legislation, in particular, creation of a single codex and migration police

  15. Managing Migration: The Brazilian Case

    OpenAIRE

    Eduardo L. G. Rios-Neto

    2005-01-01

    The objective of this paper is to present the Brazilian migration experience and its relationship with migration management. The article is divided into three parts. First, it reviews some basic facts regarding Brazilian immigration and emigration processes. Second, it focuses on some policy and legal issues related to migration. Finally, it addresses five issues regarding migration management in Brazil.

  16. TOWARD MIGRATION TRANSITION IN ROMANIA

    OpenAIRE

    Cristian Incaltarau

    2012-01-01

    Most studies regarding the contribution of migration to development are limited to an isolated analysis of the economic effects of migration. But the migration process is in turn influenced by other processes. So a wider framework including migration and other processes of development would be more appropriate. The experience of South European and East Asian countries have shown us that, during development, countries can change their migration profile from emigration to immigration. The prese...

  17. Biometrics and international migration.

    Science.gov (United States)

    Redpath, Jillyanne

    2007-01-01

    This paper will focus on the impact of the rapid expansion in the use of biometric systems in migration management on the rights of individuals; it seeks to highlight legal issues for consideration in implementing such systems, taking as the starting point that the security interests of the state and the rights of the individual are not, and should not be, mutually exclusive. The first part of this paper briefly describes the type of biometric applications available, how biometric systems function, and those used in migration management. The second part examines the potential offered by biometrics for greater security in migration management, and focuses on developments in the use of biometrics as a result of September 11. The third part discusses the impact of the use of biometrics in the management of migration on the individual's right to privacy and ability to move freely and lawfully. The paper highlights the increasing need for domestic and international frameworks to govern the use of biometric applications in the migration/security context, and proposes a number of issues that such frameworks could address. PMID:17536151

  18. Prestack depth migration

    International Nuclear Information System (INIS)

    Two lines form the southern North Sea, with known velocity inhomogeneities in the overburden, have been pre-stack depth migrated. The pre-stack depth migrations are compared with conventional processing, one with severe distortions and one with subtle distortions on the conventionally processed sections. The line with subtle distortions is also compared with post-stack depth migration. The results on both lines were very successful. Both have already influenced drilling decisions, and have caused a modification of structural interpretation in the respective areas. Wells have been drilled on each of the lines, and well tops confirm the results. In fact, conventional processing led to incorrect locations for the wells, both of which were dry holes. The depth migrated sections indicate the incorrect placement, and on one line reveals a much better drilling location. This paper reports that even though processing costs are high for pre-stack depth migration, appropriate use can save millions of dollars in dry-hole expense

  19. Derivation of the Freundlich Adsorption Isotherm from Kinetics

    Science.gov (United States)

    Skopp, Joseph

    2009-01-01

    The Freundlich adsorption isotherm is a useful description of adsorption phenomena. It is frequently presented as an empirical equation with little theoretical basis. In fact, a variety of derivations exist. Here a new derivation is presented using the concepts of fractal reaction kinetics. This derivation provides an alternative basis for…

  20. ISOTHERMAL AND THERMOMECHANICAL FATIGUE OF A NICKEL-BASE SUPERALLOY

    Directory of Open Access Journals (Sweden)

    Carlos Carvalho Engler-Pinto Júnior

    2014-06-01

    Full Text Available Thermal gradients arising during transient regimes of start-up and shutdown operations produce a complex thermal and mechanical fatigue loading which limits the life of turbine blades and other engine components operating at high temperatures. More accurate and reliable assessment under non-isothermal fatigue becomes therefore mandatory. This paper investigates the nickel base superalloy CM 247LC-DS under isothermal low cycle fatigue (LCF and thermomechanical fatigue (TMF. Test temperatures range from 600°C to 1,000°C. The behavior of the alloy is strongly affected by the temperature variation, especially in the 800°C-1,000°C range. The Ramberg-Osgood equation fits very well the observed isothermal behavior for the whole temperature range. The simplified non-isothermal stress-strain model based on linear plasticity proposed to represent the thermo-mechanical fatigue behavior was able to reproduce the observed behavior for both in-phase and out-of-phase TMF cycling.

  1. Isothermal Gas assisted displacement of a polystyrene melt

    DEFF Research Database (Denmark)

    Eriksson, Torbjörn Gerhard; Rasmussen, Henrik K.

    2007-01-01

    Isothermal gas displacements of a polystyrene melt (shaped as circular cylinder with a radius of 2.5mm) placed inside a circular steel annulus were performed. A flow valve ensures a constant flow rate and rotational symmetric flow during the displacement. The experiments show an increase in the...

  2. Isothermal martensite formation at sub-zero temperatures

    DEFF Research Database (Denmark)

    Stojko, Allan; Hansen, Mikkel Fougt; Slycke, Jan;

    2010-01-01

    austenitized and quenched in oil and thereafter investigated with vibrating sample agnetometry, which allows a quantitative assessment of the fraction of retained austenite as a function of the subzero temperature and time. Isothermal martensite formation was observed on interrupting the continuous cooling (5...

  3. Isothermal Titration Calorimetry Can Provide Critical Thinking Opportunities

    Science.gov (United States)

    Moore, Dale E.; Goode, David R.; Seney, Caryn S.; Boatwright, Jennifer M.

    2016-01-01

    College chemistry faculties might not have considered including isothermal titration calorimetry (ITC) in their majors' curriculum because experimental data from this instrumental method are often analyzed via automation (software). However, the software-based data analysis can be replaced with a spreadsheet-based analysis that is readily…

  4. The granulometrical fractions of soil, distributions of caesium-137 on its and the fastening of soil surface contaminated by radionuclides at locations of the 'Azgir test site'

    International Nuclear Information System (INIS)

    products of chain reaction in the moment of UGNE; radioactive ejections from spaces after explosions; contamination of locations during the break-down of spaces and a fulfilment of technological operations of different purposes; a burial of radioactive wastes in trenches in the limits of locations; local traces of atmospherical falls - out from radioactive clouds, formed as a result of the Chernobyl Catastrophe (traces were discovered during aero-gamma-spectro metrical surveys, carried out in the beginning of 1990). Accordingly to a change of granulometric composition there was taken place and a redistribution of caesium-137, the main part of which was concentrated in the fraction of 0.063 mm and was in limits of from 79.5% up to 92.2%. An efficiency of an action of polymeric composition, introduced into soil for fastening and binding of radionuclides in surface soil layer, can be estimated by data of measurements of caesium-137 distribution in granulometric fractions of soil samples, sieved and divided into 6 dimension components: 1.25 mm; 0.7 mm; 0.4 mm; 0.1 mm; 0.063 mm and <0.063 mm. Further, in indicated probes, by the method of wet sieving, there was also determined the granulometric composition by 6 above-mentioned fraction and the additional seventh fraction ('clay'), extracted during the wet sieving of soil samples. Then, in each obtained fraction there was measured the specific activity of caesium-137. In order to study the real distribution of caesium-137 on granulometric fractions there were measured specific activities of caesium-137 in all fractions, extracted after wet sieving and analogous to those, which were obtained during dry sieving, and in the fraction 'clay', formed during the process of wash-out of soil probes by water. The use of wet sieving had led to the redistribution of caesium-137 content in fractions, which was fixed by the method of dry sieving, where caesium-137 was mainly in fractions : 0.1 mm; 0.4 mm; 0.7 mm and 1.25 mm. In the same

  5. En fornemmelse for migration

    DEFF Research Database (Denmark)

    Schütze, Laura Maria

    Afhandlingen undersøger, hvordan sted, museets rolle som aktør og religion er relevante for produktionen af migration på Immigrantmuseet (2012) og i Københavns Museums udstilling At blive københavner (2010). Afhandlingen er baseret på udstillingsanalyse samt interview med relevant museumsfagligt......, anvendes som virkemidler til at nuancere migration og distancere udstillingen fra den offentlige debat om indvandring. Afhandlingen peger på, at produktionen af den nyere danske historie på museum er præget af et fravær af religion. Det skyldes, at de museumsfaglige praksisser og traditioner afspejler en...... identiteter, som vi tager for givet: nationer, byer, kvinder - såvel som migration og religion. Afhandlingen argumenterer følgelig for, at museernes produktion af (materiel) religion er et særdeles relevant, men kun ringe udforsket, genstandsfelt for religionssociologien....

  6. Migration Outflows and Optimal Migration Policy: Rules versus Discretion

    OpenAIRE

    Ismaël Issifou; Francesco Magris

    2015-01-01

    We study the effects of more open borders on return migration and show that migrants are more likely to return to the origin country when migration rules are softer, because this implies that they could more easily re-migrate if return migration is unsuccessful. As a result, softening migration rules leads to lower net inflows than generally acknowledged. We show that if government follows rules to shape the optimal migration policy, it will chose more open borders than in the case its behavi...

  7. Caesium absorption by barley - influence of its retention by the soil - competitive action of potassium; Absorption du cesium par l'orge - influence de sa retention dans le sol - action competitive du potassium

    Energy Technology Data Exchange (ETDEWEB)

    Ferron-Trosseau, F. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1964-06-01

    We have studied, in various culture media, how the absorption of caesium by barley varies with its concentration, and how this absorption can be in competition with a similar alkali cation-potassium. We have also considered the caesium distribution in the ground in particular radio-active caesium, between the soil and solution, as a function of the amount of caesium. From our work it is clear that barley behaves very differently according to whether the caesium is in a nutritive solution or is in the soil: for a nutritive solution, the fraction of caesium (radioactive and stable) absorbed by barley remains practically constant in the presence of increasing amounts (relatively small) of stable caesium; in soil, the fraction of the radio-active caesium absorbed increases as the stable caesium content (fairly low) of the soil increases, in relationship with a rapidly decreasing selectivity of the soil for Cs{sup +}. The difference between these results is thus explained by the very pronounced selectivity of the illitic soil studied for Cs{sup +}, as long as the proportion of Cs remains low, about as low as that of most natural soils. Furthermore, the K{sup +} ion is in competition with the Cs{sup +} ion, for absorption by barley in a culture medium in a nutritive solution or in soil, only when the potassium concentrations are relatively low, of the order of the nutritive maximum. This shows that the addition of potassium to a medium already rich in this element does not reduce the absorption of caesium by barley. The choice of experimental conditions close to natural conditions (nutritive media strong in calcium) and the examination of the distribution of radioactive caesium between the soil, the soil solution and the plant in the presence of very low doses of stable caesium make these results interesting from the 'atomic health' point of view; it should be expected that a definite contamination risk exists for plants cultivated on synthetic media and for

  8. [Migration and diabetes].

    Science.gov (United States)

    Aydinkoc-Tuzcu, Kadriye; Schindler, Karin; Kautzky-Willer, Alexandra; Ludvik, Bernhard; Fasching, Peter

    2016-04-01

    The article deals with the demographic data of migration in Austria and with therapeutic advice concerning drug therapy and diabetes education for patients with migration background. In this context socio-cultural specifics are discussed. These suggestions are seen complementary to the general treatment guidelines of the Austrian Diabetes Association.Especially for the fast months Ramadan there are a lot of informations. The most important point is that the patient care must be highly individualized and the management plan may differ for each patient. PMID:27052237

  9. Migration of seismic data

    International Nuclear Information System (INIS)

    Prospecting for oil and gas resources poses the problem of determining the geological structure of the earth's crust from indirect measurements. Seismic migration is an acoustic image reconstruction technique based on the inversion of the scalar wave equation. Extensive computation is necessary before reliable information can be extracted form large sets of recorded data. In this paper a collection of open-quotes industrialclose quotes migration techniques, each giving rise to a data parallel algorithm, is outlined. Computer simulations on synthetic seismic data illustrate the problem and the approach

  10. Making Migration Meaningful

    DEFF Research Database (Denmark)

    Benwell, Ann Fenger

    2013-01-01

    . The article focuses on changing patterns of mobility in the Mongolian ‘age of the market’ and its effects on population groups. Internal and international migration has continually risen as individuals and families have moved to places of opportunity. Connections are believed to be maintained during...... periods of absence by migrant family members, as both men and women are culturally permitted to be separate from their families. Migration is understood to contribute to prosperity, and separations contribute to generate growth and hishig (good fortune) for the good of the family. However, such mobility...

  11. Unix Application Migration Guide

    CERN Document Server

    Microsoft. Redmond

    2003-01-01

    Drawing on the experience of Microsoft consultants working in the field, as well as external organizations that have migrated from UNIX to Microsoft® Windows®, this guide offers practical, prescriptive guidance on the issues you are likely to face when porting existing UNIX applications to the Windows operating system environment. Senior IT decision makers, network managers, and operations managers will get real-world guidance and best practices on planning and implementation issues to understand the different methods through which migration or co-existence can be accomplished. Also detailing

  12. [Migration, climate and health].

    Science.gov (United States)

    Tellier, Siri; Carballo, Manuel; Calballo, Manuel

    2009-10-26

    Many tentative connections have been postulated between migration and climate. This article points to rural-urban migration, particularly into low elevation urban slums prone to flooding as an issue needing urgent attention by health professionals. It also notes the no-man's land in which environmental refugees find themselves and the consequences this may have. Finally, it points to the urgent need to reform health systems in both developing and developed countries to adapt to rapidly changing disease patterns and to become more responsive to them. PMID:19857400

  13. Migration = cloning; aliasiing

    DEFF Research Database (Denmark)

    Hüttel, Hans; Kleist, Josva; Nestmann, Uwe;

    1999-01-01

    In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider the creat......In Obliq, a lexically scoped, distributed, object-oriented programming language, object migration was suggested as the creation of a copy of an object’s state at the target site, followed by turning the object itself into an alias, also called surrogate, for the remote copy. We consider...

  14. Is Migration Feminized?

    OpenAIRE

    Toksöz, Gülay

    2012-01-01

    In the context of Turkey’s accession to the EU, the issue of potential migration from Turkey and its impact upon European labor markets became one of the concerns of the EU, considering Turkey’s growing population and young labor force. In 2011, half a century after the bi-lateral agreement between Turkey and Germany on labor recruitment in 1961, migration plays a key role in relations of Turkey with the EU and will even increase its significance – not necessarily for the next fifty years bu...

  15. 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

    Science.gov (United States)

    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 m

  16. Computer modelling of the chemical speciation of caesium, uranium(VI) and neptunium(V) in human duodenal fluids under fasting conditions

    International Nuclear Information System (INIS)

    A model simulating the human duodenal contents under physiologically realistic, fasting conditions was developed using the joint expert speciation system (JESS) computer program and database and used to investigate the chemical speciation of caesium, uranium(VI) and neptunium(V). Over the pH range 5.0-9.0, and the concentration range 5x10-15-5x10-5 mol dm-3, caesium was predicted to occur predominantly as the absorbable free monovalent cation Cs+ (∼95%) with species such as CsHPO4- and CsCl representing the remainder. The presence or absence of sulphate at 2.1x10-3 mol dm-3 did not influence the predicted speciation. Uranium was predicted to be present entirely as a soluble, highly charged species, both in the absence and in the presence of sulphate. Between pH 5.0 and ∼6.5 the UO2H2(PO4)22- predominated, above this pH carbonate species, either UO2(CO3)46- or, possibly, UO2(CO3)58-. At pH 8.0, and in the presence of sulphate, neptunium(V) was predicted to exist solely as the tetrasulphate species, whilst in the absence of sulphate, an array of negatively charged soluble carbonate species predominated. Studies over the pH range 5.0-9.0 predicted the formation of a spectrum of negatively charged carbonate and phosphate species, ∼40% of the total neptunium was predicted to be present as the electrically net-neutral species NpO2HCO3 at pH6.0, ∼20% at pH 7.0, ∼10% at pH 7.5 and ∼1% at pH 8.0. The observed speciation patterns of uranium and neptunium did not change over the concentration range 5x10-15-5x10-5 mol dm-3 and no solid species were predicted to occur under the conditions simulated. Whether the predicted electrically net-neutral neptunium species or the uranium pentacarbonate species do actually occur under true physiological conditions remains to be established. The observed speciation patterns for caesium and uranium are consistent with the observed absorption of these elements by humans; however, the observations for neptunium appear to be

  17. [Migration and health].

    Science.gov (United States)

    Litvinjenko, S

    1997-01-01

    In the last decades of this century we are witnesses of frequent crises in different parts of the world produced by internal disturbance and wars. These crises, together with natural disasters, poverty and hunger, follow the history of mankind often forcing huge population groups to leave their homes. The harmful health consequences are among negative effects of migrations. While stable populations have well-tried routines for maintaining health, migrations mean abandoning such support systems. The increased exposure to harmful factors contributes more to the bad health condition of the migrant population. Setting of newcomers and local people together in the same homes, reduction in food and heating resources, drug shortage as well as importation of new infectious agents, may also endanger health of the native population. These observations have also been confirmed by Yugoslav experience. Depending on the fact whether a migration is elemental or organized i.e. dependent on its place in the large scale between these two extreme endpoints, the size of risk is also dependent on the consequences and degree of their difficulty. Mass health disturbances occur during migrations of the population from war regions, migrations from areas of natural disasters, mass pilgrimage, migrations of seasonal workers and migrations of armies during wars. However, even in these difficult times and conditions, a good organization can contribute to the mitigation of harmful consequences caused by these migrations. For instance, in 1942 there was an epidemic of typhus fever in Bosnia when many refugees crossed the Drina river on the way to Serbia escaping from Ustasha terrorism. At the Serbian side there were checkpoints where the refugees could taka a bath and where their laundry and clothing were depediculated with dry air, and after a two-week quarantine they could continue to Serbian provinces without making new foci of typhus fever. The most vulnerable and numerous group of refugees

  18. Migration scenarii in extrasolar systems

    Directory of Open Access Journals (Sweden)

    Crida A.

    2011-02-01

    Full Text Available In this review talk, I present the theory of type I migration of small mass planets, and its latest developments that open the possibility of outward migration in the inner part of a protoplanetary disk. I also review the type II migration of giant planets, and mention the runaway, type III. Then, we focus on the migration of pairs of planets in resonance. The eccentricity of the planets raise, and possibly their mutual inclination as well. Also, the migration rate can be changed, and directed outward if the outer planet is the lighter. Last, we present a synthetic scenario of migration for the giant planets of our Solar System.

  19. MEXICAN MIGRATION PROJECT

    Science.gov (United States)

    The Mexican Migration Project is designed to make timely, high-quality data on documented and undocumented Mexican migrants available to researchers and policy analysts. Each year since 1987 the project has administered a semi-structured interview schedule to representative sampl...

  20. Brain Migration Revisited

    Science.gov (United States)

    Vinokur, Annie

    2006-01-01

    The "brain drain/brain gain" debate has been going on for the past 40 years, with irresolvable theoretical disputes and unenforceable policy recommendations that economists commonly ascribe to the lack of reliable empirical data. The recent report of the World Bank, "International migration, remittances and the brain drain", documents the…

  1. Migration and Africa

    DEFF Research Database (Denmark)

    Zoppi, Marco

    2014-01-01

    European powers imposed the nation-state on Africa through colonialism. But even after African independencies, mainstream discourses and government policies have amplified the idea that sedentariness and the state are the only acceptable mode of modernity. Migration is portrayed as a menace to the...

  2. Migration as Adventure

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2016-01-01

    Narratives of adventure constitute a well-established convention of describing travel experiences, yet the significance of this narrative genre in individuals’ accounts of their migration and life abroad has been little investigated. Drawing on Simmel and Bakhtin, among others, this article...

  3. Dispersal and migration

    Directory of Open Access Journals (Sweden)

    Schwarz, C.

    2004-06-01

    Full Text Available Ringing of birds unveiled many aspects of avian migration and dispersal movements. However, there is even much more to be explored by the use of ringing and other marks. Dispersal is crucial in understanding the initial phase of migration in migrating birds as it is to understand patterns and processes of distribution and gene flow. So far, the analysis of migration was largely based on analysing spatial and temporal patters of recoveries of ringed birds. However, there are considerable biases and pitfalls in using recoveries due to spatial and temporal variation in reporting probabilities. Novel methods are required for future studies separating the confounding effects of spatial and temporal heterogeneity of recovery data and heterogeneity of the landscape as well. These novel approaches should aim a more intensive and novel use of the existing recovery data by taking advantage of, for instance, dynamic and multistate modeling, should elaborate schemes for future studies, and should also include other marks that allow a more rapid data collection, like telemetry, geolocation and global positioning systems, and chemical and molecular markers. The latter appear to be very useful in the delineating origin of birds and connectivity between breeding and non–breeding grounds. Many studies of migration are purely descriptive. However, King and Brooks (King & Brooks, 2004 examine if movement patterns of dolphins change after the introduction of a gillnet ban. Bayesian methods are an interesting approach to this problem as they provide a meaningful measure of the probability that such a change occurred rather than simple yes/no response that is often the result of classical statistical methods. However, the key difficulty of a general implementation of Bayesian methods is the complexity of the modelling —there is no general userfriendly package that is easily accessible to most scientists. Drake and Alisauskas (Drake & Alisauskas, 2004 examine the

  4. Fall armyworm migration patterns.

    Science.gov (United States)

    Fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), infestations in most of North America arise from annual migrations of populations that overwinter in southern Texas and Florida. Cytochrome Oxidase I haplotype profiles within the fall armyworm corn-strain, the subgroup tha...

  5. Practical Data Migration

    CERN Document Server

    Morris, Johny

    2012-01-01

    This book is for executives and practitioners tasked with the movement of data from old systems to a new repository. It uses a series of steps guaranteed to get the reader from an empty new system to one that is working and backed by the user population. Using this proven methodology will vastly increase the chances of a successful migration.

  6. Migration pathways in soils

    International Nuclear Information System (INIS)

    This study looked at diffusive migration through three types of deformation; the projectile pathways, hydraulic fractures of the sediments and faults, and was divided into three experimental areas: autoradiography, the determination of diffusion coefficients and electron microscopy of model projectile pathways in clay. For the autoradiography, unstressed samples were exposed to two separate isotopes, Pm-147 (a possible model for Am behaviour) and the poorly sorbed iodide-125. The results indicated that there was no enhanced migration through deformed kaolin samples nor through fractured Great Meteor East (GME) sediment, although some was evident through the projectile pathways in GME and possibly through the GME sheared samples. The scanning electron microscopy of projectile pathways in clay showed that emplacement of a projectile appeared to have no effect on the orientation of particles at distances greater than two projectile radii from the centre of a projectile pathway. It showed that the particles were not simply aligned with the direction of motion of the projectile but that, the closer to the surface of a particular pathway, the closer the particles lay to their original orientation. This finding was of interest from two points of view: i) the ease of migration of a pollutant along the pathway, and ii) possible mechanisms of hole closure. It was concluded that, provided that there is no advective migration, the transport of radionuclides through sediments containing these defects would not be significantly more rapid than in undeformed sediments. (author)

  7. Migrating the Light

    DEFF Research Database (Denmark)

    Sørensen, Bent

    The migration of Blaga’s universalist, even centralist poems from Romanian of the first third of the 20th C. into American of the first fifth of the 21st C. illustrates the uses of Pierre Joris’s nomadic methods. My translations of Blaga read well for a teenage audience whose only exposure to lit...

  8. Migration and Narration

    Directory of Open Access Journals (Sweden)

    Brigitte Boenisch-Brednich

    2002-05-01

    Full Text Available The following article aims to work out the main narrative techniques of “telling migration”. The conclusions drawn on the subject of migration and narration are based on a one-year field work study, combining participant observation with interviewing. This study took place in New Zealand concentrating on German immigrants between 1936 and 1996. The main source for my analysis given in this paper is provided by 102 people I interviewed. The texts of these biographically-focussed interviews allowed me to work not only on an ethnographical history of migration but also to gain insights into peoples’ experiences, and over and above that, to learn what kind of stories and techniques of storytelling emigration creates. The book focuses on a comparatively wide time frame of sixty years (Boenisch- Brednich 2001. This makes it possible to analyse very different periods of migration and groups of migrants, contrasting social categories as well as exploring differences in education, milieu, age and gender. Furthermore, it becomes obvious that although all migrants were leaving Germany and arriving in New Zealand, they experienced what were in effect very different countries through time – different Germanys, different New Zealands. To work out the changing reasons for migrating (work migration, refuge, global lifestyle, etc. inside western societies is a major theme the book is aiming for. A second approach is to investigate migration from the perspective of focussing on everyday life, an investigation on the basis of personal experiences, such as “work, housing, food, celebrations, social life”. A special focus is set on the analysing of “mental narratives” as key stories, examples, comparatives etc. The central questions of this project were: What kind of strategies do people use to cope with a major changes in their biography, as constituted by emigration? What does integration really mean and how does it work for different groups? What

  9. Effect of self-interstitial cluster migration on helium diffusion in iron

    International Nuclear Information System (INIS)

    The influence of self-interstitial cluster migration on defect evolution in irradiated α-Fe is studied using an object kinetic Monte Carlo model with input from ab initio and molecular dynamics calculations. Helium implantation and desorption is simulated during isothermal annealing under different conditions of temperature and sample thickness. Results are compared with experimental measurements existing in the literature. In particular, the effect of self-interstitial cluster migration on the fraction of He released during annealing is studied. The results of these calculations point towards a strong effect of traps in the nucleation and growth of He-vacancy clusters

  10. Seasonal Survival Probabilities Suggest Low Migration Mortality in Migrating Bats

    OpenAIRE

    Giavi, Simone; Moretti, Marco; Bontadina, Fabio; Zambelli, Nicola; Schaub, Michael

    2014-01-01

    Migration is adaptive if survival benefits are larger than costs of residency. Many aspects of bat migration ecology such as migratory costs, stopover site use and fidelity are largely unknown. Since many migrating bats are endangered, such information is urgently needed to promote conservation. We selected the migrating Leisler's bat (Nyctalus leisleri) as model species and collected capture-recapture data in southern Switzerland year round during 6 years. We estimated seasonal survival and ...

  11. The behaviour of transport from the fission products caesium and strontium in coated particles for high temperature reactors under irradiation conditions

    International Nuclear Information System (INIS)

    At first survey is given about existing knowledge of the behaviour of caesium and strontium fission product transport in coated particles. In order to describe the complicated fission product transport mechanisms under irradiation conditions a suitable calculating model (SLIPPER) is taken over and modified to the special problems of an irradiation experiment. Fundamentally, the fission product transport is represented by the two contributions of diffusion and recoil, at which the diffusion is described by effective diffusion coefficients. In difference of that the possibility of a two-phase-diffusion is examined for the Cs diffusion in the fuel kernel. The model application on measuring results from irradiation experiments of KFA-Juelich and Mol-Belgien allowed the explanation from the characteristic of fission product transport in coated particles under irradiation conditions and produced effective diffusion coefficients for the fission products Cs and Sr. (orig.)

  12. Migration Turnover Rates in Mountain States Counties

    OpenAIRE

    Israelsen, William J.; Israelsen, L. Dwight; Israelsen, Ryan D.

    2006-01-01

    Studies of migration typically examine migration between countries, or, in the United States, migration between states. Recently, there have been several studies done on the determinants of migration at the county level. The current study introduces a new concept into the migration literature: the migration turnover rate (MTR). The migration turnover rate is similar to an employee turnover rate in that it measures the turnover through in-migration and out-migration of the population of an are...

  13. Migration Turnover Rates in United States Counties

    OpenAIRE

    Israelsen, L. Dwight; Israelsen, Ryan D.; Israelsen, William J.

    2006-01-01

    Studies of migration typically examine migration between countries, or, in the United States, migration between states. Recently, there have been several studies done on the determinants of migration at the county level. The current study introduces a new concept into the migration literature: the migration turnover rate (MTR). The migration turnover rate is similar to an employee turnover rate in that it measures the turnover through in-migration and out-migration of the population of an are...

  14. Globalization, Migration and Development

    Directory of Open Access Journals (Sweden)

    George, Susan

    2002-01-01

    Full Text Available EnglishMigration may become the most important branch of demography in the earlydecades of the new millennium in a rapidly globalizing world. This paper discusses the causes, costsand benefits of international migration to countries of the South and North, and key issues of commonconcern. International migration is as old as national boundaries, though its nature, volume,direction, causes and consequences have changed. The causes of migration are rooted in the rate ofpopulation growth and the proportion of youth in the population, their education and training,employment opportunities, income differentials in society, communication and transportationfacilities, political freedom and human rights and level of urbanization. Migration benefits the Souththrough remittances of migrants, improves the economic welfare of the population (particularly womenof South countries generally, increases investment, and leads to structural changes in the economy.However, emigration from the South has costs too, be they social or caused by factors such as braindrain. The North also benefits by migration through enhancement of economic growth, development ofnatural resources, improved employment prospects, social development and through exposure toimmigrants' new cultures and lifestyles. Migration also has costs to the North such as of immigrantintegration, a certain amount of destabilization of the economy, illegal immigration, and socialproblems of discrimination and exploitation. Issues common to both North and South include impact onprivate investment, trade, international cooperation, and sustainable development. Both North andSouth face a dilemma in seeking an appropriate balance between importing South's labour or itsproducts and exporting capital and technology from the North.FrenchLa migration est sans doute devenue la partie la plus importante de la démographie des premières décennies du nouveau millénaire dans un monde qui change rapidement. Ce

  15. The International Organization for Migration in Global Migration Governance

    OpenAIRE

    Poulsen, Sofie Havn; Andersen, Lise

    2011-01-01

    This project focuses on the IOM, the notion of global governance of migration and the interaction between these two. The point of departure has been an attempt to grasp the current global approach to migration and comprehend whether, or to what degree, there is governance of migration issues taking place at a global level.

  16. Monitoring of caesium-137 in food plants and muscle from moose, red deer and wild reindeer in 2010.; Overvaaking av cesium-137 i beitevekster og kjoett av elg, hjort og villrein i 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Veiberg, Vebjoern; Gaare, Eldar; Stokke, Sigbjoern; Solberg, Erling J.; Skuterud, Lavrans

    2011-07-01

    The monitoring of Cs-137 fall-out from the Chernobyl accident in 1986, started the same year. Several plants and wild reindeer in natural ecosystems in Nord-Rondane have been followed annually ever since. Four more wild reindeer ranges were included in 2001: Setesdal-Ryfylkeheiene, Hardangervidda, Nord-Ottadalen, Snoehetta and Nord-Rondane. From 2007 Forollhogna was also included. On fixed plots in Nord-Rondane and Snoehetta some of the reindeer forage plants, including both higher plants and fruticose lichens, have been sampled and analyzed annually since 1986. This was also done in 2010. In addition plants and lichens were sampled at five locations along an altitudinal gradient at Soendre Knutshoe, and at 7-8 locations along an east-west gradient from Kollaflata to Skarhoe in the Jora valley continuing along the Aursjoe to Torbudalen. All these locations were sampled annually between 1987-1990, but they have not been sampled since. In 2010 samples from red deer and moose was also collected from eight different regions located within the following counties: Oppland, Telemark, Vest-Agder, Rogaland, Sogn and Fjordane, Nord-Troendelag, Nordland and Troms. Red deer were sampled in four regions and moose in six. Both species were sampled in Oppland. In 2010 76, 49 and 61 samples were collected from wild reindeer, red deer and moose respectively. All measures of caesium levels were performed on dried samples. For the 596 samples of plants and lichen the results refer to caesium-levels in dried samples. For the meat samples, results refer to caesium-137 levels in raw meat. Due to large variation in measured levels of caesium within species and sampling area, we give median values instead of mean values.The highest caesium levels in wild reindeer were found in Snoehetta (1010 Bq/kg) and Nord-Rondane (2686 Bq/kg). The levels found in the other areas were considerably lower. The highest caesium levels in both red deer (Sel, 677 Bq/kg) and moose (Vaaga, 365 Bq/kg) were found

  17. EFFECTS OF TEMPERATURE ON TRICHLOROETHYLENE DESORPTION FROM SILICA GEL AND NATURAL SEDIMENTS. 1. ISOTHERMS. (R822626)

    Science.gov (United States)

    Aqueous phase isotherms were calculated from vapor phase desorption isotherms measured at 15, 30, and 60 C for trichloroethylene on a silica gel, an aquifer sediment, a soil, a sand fraction, and a clay and silt fraction, all at...

  18. Radionuclide migration studies in soil

    International Nuclear Information System (INIS)

    In this work a brief description about retention and migration parameters of radionuclides in soil, including main methods to determine the distribution coefficient (K) are given. Some of several factors that can act on the migration are also mentioned. (author)

  19. International Migration and Real Wages

    OpenAIRE

    Reza Oladi; Hamid Beladi

    2007-01-01

    We provide an analysis of the impact of migration on the skilled- unskilled wage gap. In particular, we show the possibility of a rise in the wage gap following the migration of skilled (unskilled ) labor.

  20. Halting Migration: Numerical Calculations of Corotation Torques in the Weakly Nonlinear Regime

    CERN Document Server

    Duffell, Paul C

    2014-01-01

    Planets in their formative years can migrate due to the influence of gravitational torques in the protoplanetary disk they inhabit. For low-mass planets in an isothermal disk, it is known that there is a strong negative torque on the planet due to its linear perturbation to the disk, causing fast inward migration. The current investigation demonstrates that in these same isothermal disks, for intermediate-mass planets, there is a strong positive nonlinear corotation torque due to the effects of gas being pulled through a gap on horseshoe orbits. For intermediate-mass planets, this positive torque can partially or completely cancel the linear (Type I) torque, leading to slower or outward migration, even in an isothermal disk. The effect is most significant for Super-Earth and Sub-Jovian planets, during the transition from a low-mass linear perturber to a non-linear gap-opening planet, when the planet has opened a so-called 'partial gap'. In this study, numerical calculations of planet-disk interactions calcula...

  1. Design of a high current extraction/strypping system using extraction and stripping isotherms

    OpenAIRE

    Danovska, Milena; Karanfilov, Dejan; Golomeova, Mirjana; Krstev, Boris; Zendelska, Afrodita

    2015-01-01

    The isotherms define the capacity of some extragent for its capability to extract required metal (in this case copper). They are used to evaluate how the system extraction/stripping works, or expected to work. The construction of extraction isotherm consists of the following stages: preparation of laboratory extragent, the organic phase is brought into contact with the electrolyte, optimization of the extraction equilibrium isotherm. Similarly, construct and stripping isotherm: or...

  2. High-temperature behaviour of IN 738 LC under isothermal and thermo-mechanical cyclic loading

    Energy Technology Data Exchange (ETDEWEB)

    Frenz, H. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Meersmann, J. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Ziebs, J. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Kuehn, H.-J. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Sievert, R. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany); Olschewski, J. [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany)

    1997-07-01

    The temperature dependence of the cyclic behavior of IN 738 LC was studied. Cyclic iso- and non-isothermal tests were performed with proportional and non-proportional tension/torsion strain paths. It was shown that maximum and minimum stress values measured in isothermal strain controlled tests correspond quite well with results of non-isothermal tests. Thermal-mechanical constitutive equations based on the viscoplastic Chaboche model were used to describe the non-isothermal stress-strain behavior. (orig.)

  3. Modelling granite migration by mesoscale pervasive flow

    Science.gov (United States)

    Leitch, A. M.; Weinberg, R. F.

    2002-06-01

    Mesoscale pervasive magma migration leads to granite injection complexes, common in hot crustal terranes. Pervasive migration is limited by magma freezing when intruding cold country rock. Here, we explore numerically the feedback mechanism between magma intrusion and heating of the country rock, which allows younger intrusive batches to reach increasingly shallower/cooler levels. This process relies on the higher solidus temperature of a rock compared to that of its melt, once melt is segregated. We define the 'free-ride layer' as the region above the melt source, where magma may freely migrate because rock temperature is above melt solidus. The top of the free-ride layer, which corresponds to the melt solidus ( TS) isotherm, is at the 'limiting depth', zS. After magma passes through the free-ride layer, the magma 'front' is always at the limiting depth. We modeled the thickening and heating of the crust above the source as melt at its liquidus ( TL) intrudes it pervasively from below. We found that: (a) magma quickly warms crust below zS to about TL, forming a step in temperature at zS; (b) the front ( zS) moves up through the crust as more magma is intruded; (c) as magma is emplaced at the front, a mingled layer of about half magma half crust forms below it, so that the total rise of the front corresponds approximately to half of the thickness of magma added to the free-ride layer; (d) the rate of rise of the front depends on the temperature difference between crust and TL, and slows down as the magma front rises; (e) for most reasonable intrusion rates and volumes, the crust above zS feels little influence of the intrusion, because the diffusion time scale is much smaller than the rise rate of the front. In summary, pervasive migration is an efficient way of heating the lower to middle crust, and can result in an injection complex several kilometers thick, consisting of about half magma and half original crust.

  4. Relation between Tolman length and isothermal compressibility for simple liquids

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Song; Zhu Ru-Zeng

    2013-01-01

    The Tolman length δ0 of a liquid with a plane surface has attracted increasing theoretical attention in recent years,but the expression of Tolman length in terms of observable quantities is still not very clear.In 2001,Bartell gave a simple expression of Tolman length δ0 in terms of isothermal compressibility.However,this expression predicts that Tolman length is always negative,which is contrary to the results of molecular dynamics simulations (MDS) for simple liquids.In this paper,this contradiction is analyzed and the reason for the discrepancy in the sign is found.In addition,we introduce a new expression of Tolman length in terms of isothermal compressibility for simple fluids not near the critical points under some weak restrictions.The Tolman length of simple liquids calculated by using this formula is consistent with that obtained using MDS regarding the sign.

  5. Entropy variation in isothermal fluid flow considering real gas effects

    Directory of Open Access Journals (Sweden)

    Maurício Guimarães da Silva

    2011-01-01

    Full Text Available The present paper concerns on the estimative of the pressure loss and entropy variation in an isothermal fluid flow, considering real gas effects. The 1D formulation is based on the isothermal compressibility module and on the thermal expansion coefficient in order to be applicable for both gas and liquid as pure substances. It is emphasized on the simple methodology description, which establishes a relationship between the formulation adopted for ideal gas and another considering real gas effects. A computational procedure has been developed, which can be used to determine the flow properties in duct with a variable area, where real gas behavior is significant. In order to obtain quantitative results, three virial coefficients for Helium equation of state are employed to determine the percentage difference in pressure and entropy obtained from different formulations. Results are presented graphically in the form of real gas correction factors, which can be applied to perfect gas calculations.

  6. Equilibrium Sequences and Gravitational Instability of Rotating Isothermal Rings

    CERN Document Server

    Kim, Woong-Tae

    2016-01-01

    Nuclear rings at centers of barred galaxies exhibit strong star formation activities. They are thought to undergo gravitational instability when sufficiently massive. We approximate them as rigidly-rotating isothermal objects and investigate their gravitational instability. Using a self-consistent field method, we first construct their equilibrium sequences specified by two parameters: alpha corresponding to the thermal energy relative to gravitational potential energy, and R_B measuring the ellipticity or ring thickness. Unlike in the incompressible case, not all values of R_B yield an isothermal equilibrium, and the range of R_B for such equilibria shrinks with decreasing alpha. The density distributions in the meridional plane are steeper for smaller alpha, and well approximated by those of infinite cylinders for slender rings. We also calculate the dispersion relations of nonaxisymmetric modes in rigidly-rotating slender rings with angular frequency Omega_0 and central density rho_max. Rings with smaller ...

  7. Resolving vortices with an isothermal HLLC Riemann solver

    CERN Document Server

    Jung, Manuel; Duschl, Wolfgang J

    2015-01-01

    The importance of contact discontinuities in 2D isothermal flows has rarely been discussed, since most Riemann solvers are derived for 1D Euler equations. We present a new contact resolving approximate Riemann solver for the isothermal Euler equations and show its performance for several one- and two-dimensional test problems. The new solver extends the well-known HLL solver, while retaining its computational simplicity. The significant gain in resolution of vortices is displayed by a simulation of the K\\'arm\\'an vortex street. We discuss the loss of Galilean invariance and its implications for the resolution of contact discontinuities, which is experienced by all modern numerical schemes for hydrodynamics in non-moving grids.

  8. Isothermal temperature reactivity coefficient measurement in TRIGA reactor

    International Nuclear Information System (INIS)

    Direct measurement of an isothermal temperature reactivity coefficient at room temperatures in TRIGA Mark II research reactor at Jozef Stefan Institute in Ljubljana is presented. Temperature reactivity coefficient was measured in the temperature range between 15 oC and 25 oC. All reactivity measurements were performed at almost zero reactor power to reduce or completely eliminate nuclear heating. Slow and steady temperature decrease was controlled using the reactor tank cooling system. In this way the temperatures of fuel, of moderator and of coolant were kept in equilibrium throughout the measurements. It was found out that TRIGA reactor core loaded with standard fuel elements with stainless steel cladding has small positive isothermal temperature reactivity coefficient in this temperature range.(author)

  9. Non-isothermal spreading of liquid drops on horizontal plates

    International Nuclear Information System (INIS)

    A viscous-liquid drop spreads on a smooth horizontal surface, which is uniformly heated or cooled. Lubrication theory is used to study thin drops subject to capillary, thermocapillary and gravity forces, and a variety of contact-angle-versus-speed conditions. It is found for isothermal drops that gravity is very important at large times and determines the power law for unlimited spreading. Predictions compare well with the experimental data on isothermal spreading for both two-dimensional and axisymmetric configurations. It is found that heating (cooling) retards (augments) the spreading process. When the advancing contact angle is zero, heating will cause the drop to spread only finitely far. For positive advancing contact angles, sufficient cooling will cause unlimited spreading. Thus, the heat transfer serves as a sentitive control on the spreading. (orig.)

  10. Construction of isotherms in solvent extraction of copper

    Directory of Open Access Journals (Sweden)

    Cvetkovski Vladimir B.

    2009-01-01

    Full Text Available The aim of this work is construction of equilibrium isotherms in solvent extraction. Technological parameters have been predicted for treatment of mine water by solvent extraction and electrowining. Two stages of extractions and one stage of stripping have been predicted for copper recovery by analyzing the equilibrium isotherms. The process was performed on mine water with 2,5 g/dm3 Cu2+, 3 g/dm Fe2+, pH 1,8, using 9 vol% LIX 984N in kerosene (organic solvent, with 95 and 98% stages efficiencies, respectively. This course produced an advanced electrolyte solution, suitable for electrowining and cathodic copper recovery, containing 51 g/dm3 Cu2+ and 160g/dm3 H2SO4 from a 30 g/dm3 Cu and 190 g/dm3 H2SO4.

  11. Non-Isothermal Desolvation Kinetics of Erythromycin A Acetone Solvate

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The desolvation of erythromycin acetone solvate was investigated under non-isothermal conditions by a thermogravimetric analyzer. This paper emphasized the kinetic analysis of non-isothermal TG-DTA data by Achar method and Coats-Redfern method to fit various solid-state reaction models, and to achieve kinetic parameters of desolvation. The mechanism of thermal desolvation was evaluated using the kinetic compensation effect. The results show that kinetics of desolvation of erythromycin acetone solvate was compatible with the mechanism of a two-dimensional diffusion controlled and was best expressed by Valensi equation. Corresponding to the integral method and the differential method, the activation energy of desolvation of erythromycin acetone solvate was estimated to be 51.26-57.11 kJ/mol, and the pre-exponential factor was 8.077 × 106 s-1-4.326 × 107 s-1,respectively.

  12. Non-isothermal Decomposition Kinetics of K(AHDNE)

    Institute of Scientific and Technical Information of China (English)

    L(U) Lei; XU Kang-zhen; QIU Qian-qian; WANG Gang; SONG Ji-rong; ZHAO Feng-qi

    2012-01-01

    The thermal behavior and non-isothermal decomposition kinetics of 1-amino-1-hydrazino-2,2-dinitroethylene potassium salt[K(AHDNE)] were studied under the non-isothermal conditions by different scanning calorimeter(DSC) method.The thermal behavior of K(AHDNE) presents three exothermic decomposition processes.The kinetic equation of the first thermal decomposition reaction obtained is da/dT=(101963/β)3(1-α)[-ln(1-α)]2/3exp(-1.862× 105/RT).The self-accelerating decomposition temperature(TSADT) and critical temperature of thermal explosion(Tb) of K(AHDNE) are 162.5 and 171.4 ℃,respectively.K(AHDNE) has higher thermal stability than AHDNE.

  13. Trade, Aid, Remittances and Migration

    OpenAIRE

    Akkoyunlu, Sule

    2009-01-01

    I investigated whether migration is interrelated with trade, aid and remittances so that any policies that consider trade, aid and remittances also affect the decision to migrate. We developed and estimated an empirical model of Turkish migration to Germany and tested the model for the 1969-2004, using the cointegration technique. A single cointegrating vector is found among the gross migration inflows and the following explanatory variables: the relative income ratio between Germany and Turk...

  14. Altruism and International Labour Migration

    OpenAIRE

    Damien Gaumont; Alice Mesnard

    1999-01-01

    This paper investigates the effect of altruism on the pattern of labour migration in a two-country overlapping generations model. We show that differences in degrees of altruism across countries lead to bilateral migration flows. Starting from the autarkic steady-state equilibrium, restrictions on labour migration are relaxed. In temporary post-migration equilibrium factor prices are equal across countries. We then characterize the unique stable steady-state equilibrium: both countries are po...

  15. The definition of illegal migration

    OpenAIRE

    DZHANSARAYEVA RIMA YERENATOVNA; MALIKOVA SHOLPAN BALTABEKOVNA

    2015-01-01

    The article analyzes the definitions of illegal migration. In theory, there is no consensus on the concept of illegal immigration. In the scientific revolution applied the concept of “illegal migration”, “illegal immigration”, “migration of the crime” and “criminal migration”. Crime and illegal migration, although they have common features, are different concepts. For the concept of illegal immigration is characterized by violation of migration laws. For the concept of mandatory criminal migr...

  16. Monitoring assembly of ribonucleoprotein complexes by isothermal titration calorimetry

    OpenAIRE

    Recht, Michael I.; Ryder, Sean P.; Williamson, James R.

    2008-01-01

    Isothermal titration calorimetry (ITC) is a useful technique to study RNA-protein interactions, as it provides the only method by which the thermodynamic parameters of free energy, enthalpy, and entropy can be directly determined. This chapter presents a general procedure for studying RNA-protein interactions using ITC, and gives specific examples for monitoring the binding of Caenorhabditis elegans GLD-1 STAR domain to TGE RNA and the binding of Aquifex aeolicus S6:S18 ribosomal protein hete...

  17. Isothermal pumping analysis for high-altitude tethered balloons

    OpenAIRE

    Kuo, Kirsty A.; Hunt, Hugh E.M.

    2015-01-01

    High-altitude tethered balloons have potential applications in communications, surveillance, meteorological observations and climate engineering. To maintain balloon buoyancy, power fuel cells and perturb atmospheric conditions, fluids could be pumped from ground level to altitude using the tether as a hose. This paper examines the pumping requirements of such a delivery system. Cases considered include delivery of hydrogen, sulfur dioxide (SO2) and powders as fluid-based slurries. Isothermal...

  18. Unsteady Heat Transfer From a Non Isothermal Rotating Disc

    Directory of Open Access Journals (Sweden)

    Bal Krishan

    1967-01-01

    Full Text Available An analytic solution of the energy equation is obtained for a non-isothermal disc rotating in an incompressible fluid at rest neglecting the viscous dissipation. Initially the disc and the fluid are at a common temperature. Without altering the velocity, the disc temperature is then changed and maintained at temperature varying according to the power law of radial distance. Expressions for temperature distribution in the fluid for large and small times have been evaluated.

  19. Isothermal Crystallization Kinetics of Palm Oil with Additives

    OpenAIRE

    Su, N.; Li, Y. M.; X.P. Bai; Zhang, Y.Z.; Liu, H. X.; Li, J.Q.; Jie, P

    2015-01-01

    This study investigates the isothermal crystallization kinetics of palm oil with additives by Differential Scanning Calorimetry (DSC). The induction time of nucleation and crystallization are obtained by simulating the crystal process using the Gompertz model. The equilibrium melting temperature is obtained via the Hoffman-Weeks methods. The Gibbs free energy of nucleation was calculated by using the Fisher-Turnbull equation and the equilibrium melting temperature. The results indicate that t...

  20. Can Hydrostatic Cores Form Within Isothermal Molecular Clouds?

    OpenAIRE

    Vazquez-Semadeni, Enrique; Shadmehri, Mohsen; Ballesteros-Paredes, Javier

    2002-01-01

    Under the assumptions that molecular clouds are nearly spatially and temporally isothermal and that the density peaks (``cores'') within them are formed by turbulent fluctuations, we argue that cores cannot reach a hydrostatic (or magneto-static) state as a consequence of their formation process. In the non-magnetic case, stabilization requires a Bonnor-Ebert truncation at a finite radius, which is not feasible for a single-temperature flow, unless it amounts to a shock, which is clearly a dy...

  1. Rapid compressions in a captive bubble apparatus are isothermal

    OpenAIRE

    Yan, Wenfei; Hall, Stephen B.

    2003-01-01

    Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting 10 min after the compression when the two phases shou...

  2. Parameter identification in non-isothermal nucleation and growth processes

    International Nuclear Information System (INIS)

    We study non-isothermal nucleation and growth phase transformations, which are described by a generalized Avrami model for the phase transition coupled with an energy balance to account for recalescence effects. The main novelty of our work is the identification of temperature dependent nucleation rates. We prove that such rates can be uniquely identified from measurements in a subdomain and apply an optimal control approach to develop a numerical strategy for its computation. (paper)

  3. Numerical Computation of Two Dimensional Wind Accretion of Isothermal Gas

    OpenAIRE

    Shima, Eiji; Matsuda, Takuya; Anzer, Ulrich; Borner, Gerhard; Boffin, Henri M. J.

    1998-01-01

    A new numerical algorithm for calculating isothermal wind accretion flows has been developed and is applied here to the analysis of the hydrodynamics of two-dimensional plane symmetric accretion flows in wind-fed sources. Polar coordinates are used to ensure fine resolution near the object. It is found that a thin accretion column is formed which shows wave-like oscillations. Small accretion disks are formed temporarily around the object. Mass accretion rate and angular momentum accretion rat...

  4. Sorption Isotherms and Probability Theory of Complex Systems

    OpenAIRE

    Brouers, F.

    2013-01-01

    We show that most of the empirical or semi-empirical isotherms proposed to extend the Langmuir formula to sorption (adsorption, chimisorption and biosorption) on heterogeneous surfaces in the gaseous and liquid phase belong to the family and subfamily of the Burr_{XII} cumulative distribution functions. As a consequence they obey relatively simple differential equations which describe birth and death phenomena resulting from mesoscopic and microscopic physicochemical processes. Using the prob...

  5. A mathematical model for isothermal heap and column leaching

    OpenAIRE

    L.R.P. de Andrade Lima

    2004-01-01

    Leaching occurs in metals recovery, in contaminated soil washing, and in many natural processes, such as fertilizer dissolution and rock weathering. This paper presents a model developed to simulate the transient evolution of the dissolved chemical species in the heap and column isothermal leaching processes. In this model, the solid bed is numerically divided into plane layers; the recovery of the chemical species, the enrichment of the pregnant leach solution, and the residual concentration...

  6. Isothermal glass transitions in supercooled and overcompressed liquids

    Science.gov (United States)

    Alba-Simionesco, C.

    1994-02-01

    We report the first calorimetric characterization of isothermal glass transitions obtained by changing the pressure at constant temperature. This isothermal glass transition is described in the case of m-fluoroaniline, a so-called fragile liquid. The method employed is based on Maxwell's equations and involves measurement of the heat of compression of a sample enclosed in a hydrostatic pressure cell under isothermal and reversible conditions. A discontinuity of the thermodynamic quantity αV, where α is the expansivity and V is the molar volume, defines the glass transition pressure Pg at which ergodicity is broken on the time scale of the experiments (300-1000 s) which depends on the pressure step employed. The step in αV is found initially to decrease rapidly with increasing pressure. The slope (∂Pg/∂T)τ seems smaller than that determined by the usual isobaric methods, implying some distinction in the degrees of freedom involved and associated differences in defining the values of Tg. Because of the high sensitivity and stability of the calorimeter, we can also observe annealing effects in the overcompressed glass at a pressure above Pg; the slow dynamic processes associated are called entropic relaxation because it is the entropy which is measured directly. An approximate relaxation function and a model for the compression data are discussed. Keeping in mind the overall pattern of ``strong and fragile'' liquid behavior, isothermal pressure variations appear to offer a useful tool to connect these extremes and may constrain the glass transition of a molecular liquid in a particular range of the P-T diagram. The concept of Kauzmann pressure PK is introduced, but it is noted that PK must become less well defined the further from ambient pressure it lies due to the decrease in ΔαV which is observed with increasing pressure.

  7. Microstructural change during isothermal aging in high manganese austenitic steels

    International Nuclear Information System (INIS)

    Microstructural change during isothermal aging has been investigated in 13%Mn-0.9%C and 22%Mn-0.6%C steels by means of optical and electron microscopy and X-ray diffractometry. High manganese austenitic steels undergo three kinds of reactions during isothermal aging; (1) grain boundary precipitation of carbide, (2) precipitation of platelet carbide within austenite (γ) grains and (3) formation of lamellar structure through eutectoid transformation (γ → ferrite (α + carbide). In 13%Mn-0.9%C steel, all of the reactions occur and the carbide concerning the reactions is M3C in any case. On the other hand, in 22%Mn-0.6%C steel, only two of them occur; grain boundary precipitation of M23C6 carbide (not M3C) and the eutectoid transformation (γ → α + M3C). Besides, both of the two reactions in 22%Mn-0.6%C steel were effectively suppressed due to the chemical composition; high Mn and low C content. Eutectoid transformation proceeds by being supplied carbon from untransformed γ, so that this results in the shortage of carbon in untransformed γ during isothermal aging and the γ phase undergoes γ → ε (hcp) martensitic transformation on the following cooling. (author)

  8. Micromechanisms of thermomechanical fatigue: A comparison with isothermal fatigue

    Science.gov (United States)

    Bill, R. C.

    1986-01-01

    Thermomechanical Fatigue (TMF) experiments were conducted on Mar-M 200, B-1900, and PWA-1480 (single crystals) over temperature ranges representative of gas turbine airfoil environments. The results were examined from both a phenomenological basis and a micromechanical basis. Depending on constituents present in the superalloy system, certain micromechanisms dominated the crack initiation process and significantly influenced the TMF lives as well as sensitivity of the material to the type TMF cycle imposed. For instance, high temperature cracking around grain boundary carbides in Mar-M 200 resulted in short in-phase TMF lives compared to either out-of-phase or isothermal lives. In single crystal PWA-1480, the type of coating applied was seen to be the controlling factor in determining sensitivity to the type of TMF cycle imposed. Micromechanisms of deformation were observed over the temperature range of interest to the TMF cycles, and provided some insight as to the differences between TMF damage mechanisms and isothermal damage mechanisms. Finally, the applicability of various life prediction models to TMF results was reviewed. Current life prediction models based on isothermal data must be modified before being generally applied to TMF.

  9. Isothermal dust models of Herschel-ATLAS galaxies

    CERN Document Server

    Smith, D J B; Jarvis, M J; Maddox, S J; Dunne, L; Bonfield, D G; Eales, S; Serjeant, S; Thompson, M A; Baes, M; Clements, D L; Cooray, A; De Zotti, G; Gonzàlez-Nuevo, J; van der Werf, P; Virdee, J; Bourne, N; Dariush, A; Hopwood, R; Ibar, E; Valiante, E

    2013-01-01

    We use galaxies from the Herschel-ATLAS survey, and a suite of ancillary simulations based on an isothermal dust model, to study our ability to determine the effective dust temperature, luminosity and emissivity index of 250um selected galaxies in the local Universe (z < 0.5). As well as simple far-infrared SED fitting of individual galaxies based on chi^2 minimisation, we attempt to derive the best global isothermal properties of 13,826 galaxies with reliable optical counterparts and spectroscopic redshifts. Using our simulations, we highlight the fact that applying traditional SED fitting techniques to noisy observational data in the Herschel Space Observatory bands introduces artificial anti-correlation between derived values of dust temperature and emissivity index. This is true even for galaxies with the most robust detections in our sample, making the results hard to interpret. We apply a method to determine the best-fit global values of isothermal effective temperature and emissivity index for z <...

  10. Disjoining pressure isotherms of water-in-bitumen emulsion films.

    Science.gov (United States)

    Taylor, Shawn D; Czarnecki, Jan; Masliyah, Jacob

    2002-08-01

    In the oil sands industry, undesirable water-in-oil emulsions are often formed during the bitumen recovery process where water is used to liberate bitumen from sand grains. Nearly all of the water is removed except for a small percentage (approximately 1 to 2%), which remains in the solvent-diluted bitumen as micrometer-sized droplets. Knowledge of the colloidal forces that stabilized these water droplets would help to increase our understanding of how these emulsions are stabilized. In this study, the thin liquid film-pressure balance technique has been used to measure isotherms of disjoining pressure in water/toluene-diluted bitumen/water films at five different toluene-bitumen mass ratios. Even though a broad range of mass ratios was studied, only two isotherms are obtained, indicating a possible change in the molecular orientation of surfactant molecules at the bitumen/water interfaces. At low toluene-bitumen mass ratios, the film stability appears to be due to a strong, short-range steric repulsion created by a surfactant bilayer. Similar isotherms were obtained for water/toluene-diluted asphaltene/water films, indicating that the surface active material at the interface probably originated from the asphaltene fraction of the bitumen. However, unlike the bitumen films, films of toluene-diluted asphaltenes often formed very rigid interfaces similar to the "protective skin" described by other researcher. PMID:16290773

  11. Gravitational lensing properties of an isothermal universal halo profile

    Institute of Scientific and Technical Information of China (English)

    Xin-Zhong Er

    2013-01-01

    N-body simulations predict that dark matter halos with different mass scales are described by a universal model,the Navarro-Frenk-White (NFW) density profiles.As a consequence of baryonic cooling effects,these halos will become more concentrated,and similar to an isothermal sphere over a large range in radii (~ 300 h-1 kpc).The singular isothermal sphere (SIS) model however has to be truncated artificially at large radii since it extends to infinity.We model a massive galaxy halo as a combination of an isothermal sphere and an NFW density profile.We give an approximation for the mass concentration at different baryon fractions and present exact expressions for the weak lensing shear and flexion for such a halo.We compare the lensing properties with the SIS and NFW profiles.We find that the combined profile can generate higher order lensing signals at small radii and is more efficient in generating strong lensing events.In order to distinguish such a halo profile from the SIS or NFW profiles,one needs to combine strong and weak lensing constraints for small and large radii.

  12. Non-isothermal Crystallization Kinetics of Kaolin Modified Polyester

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ruixin; GU Mingbo; CHEN Guoqiang

    2011-01-01

    Fiber-class modified kaolin and PET have been blended in the twin-screw and granulated to chips containing 4 wt% of kaolin.Non-isothermal crystallization process of kaolin modified polyester was investigated using a differential scanning calorimetry (DSC),and the addition of kaolin enhances either the melting temperature (Tm) or the crystallization temperature (Tc).The morphology of kaolin modified polyester,the melt of which is cooled at different cooling rate,was observed by scanning electron microscope (SEM).The relationship between Tc and cooling rate F was studied.Semi-crystalline phase t1/2 makes an exponential decline with increasing F,and the higher the cooling rate,the shorter the time of crystallization completion.Non-isothermal crystallization kinetics parameters and the activation energy were calculated,indicating that the higher rate of cooling needs the higher relative crystallinity in the unit crystallization time,the crystallization rate increased while speeding up the temperature reduction,and the activation energy AE was calculated to be -204.1566 kJ/mol for the non-isothermal crystallization processes by the Kissinger's methods.

  13. Religion, migration og integration

    DEFF Research Database (Denmark)

    Borup, Jørn

    2010-01-01

    Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i integrationss......Sammenhængen mellem religion og integration har de sidste år været genstand for debat. Artiklen kommer ind på begreber og sammenhænge relateret til området (migration, diaspora, assimilation, etnicitet, kultur) og ser på religionens mulige rolle som negativ eller positiv ressource i...

  14. Migration and Pension

    OpenAIRE

    Assaf Razin; Efraim Sadka

    1998-01-01

    Migration has important implications for the financial soundness of the pension system, which is an important pillar of the welfare state. While it is common sense to expect that young migrants, even if low-skilled, can help society pay the benefits to the currently elderly, it may nevertheless be reasonable to argue that these migrants would adversely affect current young since, after all, the migrants are net beneficiaries of the welfare state. In contrast to the adverse effects of low skil...

  15. MIGRATION AND POLITICAL ASYLUM

    OpenAIRE

    LUPSA FLORENTINA

    2014-01-01

    Migration is an important topic on the public agenda, as well as in the area of effervescent political debate and public policies, and has been so especially in this past decade, in the national and European plane. The recorded evolutions may easily exemplify the way in which liberal democracies function and the process of European construction, implicitly the process of change in the immigration policy, degree of adaptability and opening to change, the controversial character and the difficu...

  16. Halting Planetary Migration

    OpenAIRE

    Lecar, M.; Sasselov, D. D.

    1999-01-01

    When Jupiter's Roche Lobe radius exceeded the scale height of the protoplanetary disk, Jupiter opened a gap in the disk. When the gap was wide enough, tidal torques from the disk interior and exterior to Jupiter were suppressed and migration continued on the accretion time scale. In the 'minimum solar nebula' about two Jupiter masses of gas remained between Jupiter and Saturn and about five Jupiter masses between Jupiter and Uranus. Unless all but a Jupiter mass of the outer disk was removed,...

  17. Enforcement and illegal migration

    OpenAIRE

    Orrenius, Pia

    2014-01-01

    Border enforcement of immigration laws attempts to raise the costs of illegal immigration, while interior enforcement also lowers the benefits. Border and interior enforcement therefore reduce the net benefits of illegal immigration and should lower the probability that an individual will decide to migrate. While some empirical studies find that border and interior enforcement serve as significant deterrents to illegal immigration, immigration enforcement is costly and carries significant uni...

  18. Functorial Data Migration

    CERN Document Server

    Spivak, David I

    2010-01-01

    In this paper we present a simple database definition language: that of categories and functors. A database schema is a category and a state is a set-valued functor. We show that morphisms of schemas induce three "data migration functors" that translate states from one schema to the other in canonical ways. Database states form a boolean topos of which the classical "relational algebra" is a fragment. These ideas thus create a new denotational semantics for database theory.

  19. Schwerpunktbericht: Migration und Gesundheit

    OpenAIRE

    Razum, Oliver; Meesmann, Uta; Bredehorst, Maren; Brzoska, Patrick; Dercks, Tanja; Glodny, Susanne; Zeeb, Hajo; Schenk, Liane; Salman, Ramazan; Menkhaus, Björn; Ulrich, Ralf; Saß, Anke-Christine

    2008-01-01

    Fast ein Fünftel der Menschen in Deutschland hat einen Migrationshintergrund. Sie sind entweder selbst zugewandert oder Kinder und Enkel von Zuwanderern. Ein Migrationshintergrund bringt Chancen und Risiken mit sich, sowohl für die Lebenssituation als auch für die Gesundheit. Hinweis: Auf der RKI-Homepage können Sie Daten zum Schwerpunktbericht "Migration und Gesundheit" (ergänzende Wertetabellen zu den Abbildungen) herunterladen.

  20. Migration of uranium

    International Nuclear Information System (INIS)

    Uranium migration is treated as a process leading to mobilization and concentration of uranium in ore deposits. During the formation of global zonation, uranium migration contributed to the enrichment of this radioactive metal in the Earth's crust. The process of upper mantle and crust fractionation and differentiation is the first cycle of the mobilization process which led to uranium enrichment in rocks in some areas of the upper Earth's crust that could be considered as the primordial uranium provinces. Uranium migration is related to the structural history of sial Earth's crust and sial magmatism. During orogeny conditions could be created for development of progressive metamorphism and for magma generation. The latter is the best process for uranium mobilization. The effectiveness of this process depends on the composition of the primordial rocks and the intensity of the process. The importance of the magmatism for uranium mobilization is due to the magmatic differentiation. Selectively mobilized felsitic parts of the rocks migrate and form felsitic magmatic portions, which mobilize uranium. Solutions are the best uranium mobilization agents. Their generation starts with water separation from local permeable reservoirs and finishes with water dissociation from minerals during their dehydration. Such solutions could be endogenous or exogenous, depending on the igneous or sedimentary rocks which have been deformed. Some of the solutions can have mixed origin, if deformed magmatic rocks contain exogenous water in pores and cracks and endogenous water in minerals. The mobilizing ability of the solutions depends on their energy, which could derive from their chemical compositions and from physical conditions of the geological environment. The movement of the mineralized solutions can be due to steam pressure and the pressure difference between the starting and the final point of the juvenile solutions, gravity for meteoric waters, convection in geoconvection cells

  1. Syrian Crisis and Migration

    OpenAIRE

    Pinar Yazgan; Deniz Eroglu Utku; Ibrahim Sirkeci

    2015-01-01

    With the growing insurrections in Syria in 2011, an exodus in large numbers have emerged. The turmoil and violence have caused mass migration to destinations both within the region and beyond. The current "refugee crisis" has escalated sharply and its impact is widening from neighbouring countries toward Europe. Today, the Syrian crisis is the major cause for an increase in displacement and the resultant dire humanitarian situation in the region. Since the conflict shows no signs of abating i...

  2. Managing the Mass Migration

    Institute of Scientific and Technical Information of China (English)

    Lan Xinzhen

    2012-01-01

    Big crowds and foul air on the train,frighteningly long queues and fierce clashes at the station...these are common scenes during China's Spring Festival travel rush.The annual travel peak is known as the world's biggest human migration.This year's stampede is still ongoing.Lasting over 40 days,people began retuming to their hometowns on January 8 and the final stragglers will make their way back to the cities by February 16.

  3. Conservation physiology of animal migration.

    Science.gov (United States)

    Lennox, Robert J; Chapman, Jacqueline M; Souliere, Christopher M; Tudorache, Christian; Wikelski, Martin; Metcalfe, Julian D; Cooke, Steven J

    2016-01-01

    Migration is a widespread phenomenon among many taxa. This complex behaviour enables animals to exploit many temporally productive and spatially discrete habitats to accrue various fitness benefits (e.g. growth, reproduction, predator avoidance). Human activities and global environmental change represent potential threats to migrating animals (from individuals to species), and research is underway to understand mechanisms that control migration and how migration responds to modern challenges. Focusing on behavioural and physiological aspects of migration can help to provide better understanding, management and conservation of migratory populations. Here, we highlight different physiological, behavioural and biomechanical aspects of animal migration that will help us to understand how migratory animals interact with current and future anthropogenic threats. We are in the early stages of a changing planet, and our understanding of how physiology is linked to the persistence of migratory animals is still developing; therefore, we regard the following questions as being central to the conservation physiology of animal migrations. Will climate change influence the energetic costs of migration? Will shifting temperatures change the annual clocks of migrating animals? Will anthropogenic influences have an effect on orientation during migration? Will increased anthropogenic alteration of migration stopover sites/migration corridors affect the stress physiology of migrating animals? Can physiological knowledge be used to identify strategies for facilitating the movement of animals? Our synthesis reveals that given the inherent challenges of migration, additional stressors derived from altered environments (e.g. climate change, physical habitat alteration, light pollution) or interaction with human infrastructure (e.g. wind or hydrokinetic turbines, dams) or activities (e.g. fisheries) could lead to long-term changes to migratory phenotypes. However, uncertainty remains

  4. Many Faces of Migrations

    Directory of Open Access Journals (Sweden)

    Milica Antić Gaber

    2013-12-01

    We believe that in the present thematic issue we have succeeded in capturing an important part of the modern European research dynamic in the field of migration. In addition to well-known scholars in this field several young authors at the beginning their research careers have been shortlisted for the publication. We are glad of their success as it bodes a vibrancy of this research area in the future. At the same time, we were pleased to receive responses to the invitation from representatives of so many disciplines, and that the number of papers received significantly exceeded the maximum volume of the journal. Recognising and understanding of the many faces of migration are important steps towards the comprehensive knowledge needed to successfully meet the challenges of migration issues today and even more so in the future. It is therefore of utmost importance that researchers find ways of transferring their academic knowledge into practice – to all levels of education, the media, the wider public and, of course, the decision makers in local, national and international institutions. The call also applies to all authors in this issue of the journal.

  5. Measurements and modelling of 137Cs migration into various types of soil

    International Nuclear Information System (INIS)

    The behaviour and migration of long-lived radioisotopes is an important part of information in the prediction of the consequences of radioactive contamination in agricultural areas. The soil contamination in Central and Eastern Europe after the Chernobyl accident has been high enough to study the vertical migration of radiocaesium under natural conditions. In the project presented here, the distribution of 137Cs activity concentration has been measured and analysed over the period of 1987-1999. Four sites have been selected to represent four different soil types. Samples are taken regularly from plane, grassy, uncultivated fields. After physical processing, activities are measured by gamma spectrometry. The physical and chemical processes of the migration are assumed to follow the diffusion-convection model, taking into contaminations from both the atmospheric nuclear weapon tests and the Chernobyl accident. Fits of the initial surface activities, the effective convection velocities and the effective diffusion coefficients are obtained by Monte Carlo technique. The convection velocities vary from about 0.06 to 0.4 cm/y, whereas the range of the diffusion coefficients is about 0.02 to 0.8 cm2/y. The goodness of fit is somehow characterised by the fact that the initial surface activities are in the range of 0.5-1.0 Bq/cm2, for both the Chernobyl and the nuclear tests, as expected form earlier measurements. The penetration of caesium into the soil is a very slow process, the majority of the activities is still in the top 10 cm layer. Assuming the correctness of the model for longer time periods, predictions can be made for future times. (author)

  6. Migrations in Slovenian geography textbooks

    Directory of Open Access Journals (Sweden)

    Jurij Senegačnik

    2013-12-01

    Full Text Available In Slovenia, the migrations are treated in almost all geographical textbooks for different levels of education. In the textbooks for the elementary school from the sixth to ninth grade, students acquire knowledge of the migrations by the inductive approach. Difficulty level of treatment and quantity of information are increasing by the age level. In the grammar school program a trail of gaining knowledge on migration is deductive. Most attention is dedicated to migrations in general geography textbooks. The textbooks for vocational and technical school programs deal with migrations to a lesser extent and with different approaches.

  7. A simple isothermal DNA amplification method to screen black flies for Onchocerca volvulus infection.

    Science.gov (United States)

    Alhassan, Andy; Makepeace, Benjamin L; LaCourse, Elwyn James; Osei-Atweneboana, Mike Y; Carlow, Clotilde K S

    2014-01-01

    Onchocerciasis is a debilitating neglected tropical disease caused by infection with the filarial parasite Onchocerca volvulus. Adult worms live in subcutaneous tissues and produce large numbers of microfilariae that migrate to the skin and eyes. The disease is spread by black flies of the genus Simulium following ingestion of microfilariae that develop into infective stage larvae in the insect. Currently, transmission is monitored by capture and dissection of black flies and microscopic examination of parasites, or using the polymerase chain reaction to determine the presence of parasite DNA in pools of black flies. In this study we identified a new DNA biomarker, encoding O. volvulus glutathione S-transferase 1a (OvGST1a), to detect O. volvulus infection in vector black flies. We developed an OvGST1a-based loop-mediated isothermal amplification (LAMP) assay where amplification of specific target DNA is detectable using turbidity or by a hydroxy naphthol blue color change. The results indicated that the assay is sensitive and rapid, capable of detecting DNA equivalent to less than one microfilaria within 60 minutes. The test is highly specific for the human parasite, as no cross-reaction was detected using DNA from the closely related and sympatric cattle parasite Onchocerca ochengi. The test has the potential to be developed further as a field tool for use in the surveillance of transmission before and after implementation of mass drug administration programs for onchocerciasis. PMID:25299656

  8. Migration process in Russia in 2010

    OpenAIRE

    Lilia Karachurina

    2011-01-01

    This paper deals with a scope of issues related to migration process taking place in the Russian Federation. The author focuses on the issues of labor migration and domestic migration. New legislative initiatives in the area of migration were reviewed.

  9. Migration Processes in Russia in 2011

    OpenAIRE

    Lilia Karachurina

    2012-01-01

    This paper deals with a scope of issues related to migration process taking place in the Russian Federation. The author focuses on the issues of labor migration and domestic migration. New legislative initiatives in the area of migration were reviewed.

  10. Terrestrial Planet Formation in the Presence of Migrating Super-Earths

    Science.gov (United States)

    Izidoro, André; Morbidelli, Alessandro; Raymond, Sean N.

    2014-11-01

    Super-Earths with orbital periods less than 100 days are extremely abundant around Sun-like stars. It is unlikely that these planets formed at their current locations. Rather, they likely formed at large distances from the star and subsequently migrated inward. In this work we use N-body simulations to study the effect of super-Earths on the accretion of rocky planets. In our simulations, one or more super-Earths migrates inward through a disk of Moon-size to Mars-size protoplanetary embryos and much smaller planetesimals embedded in a gaseous disk. In order to qualitatively cover possible scenarios of type-I migration for super-Earths, we have performed simulations considering many different migration speeds and configurations for these bodies. Fast-migrating super-Earths, where super-Earth’s migration is comparable to the traditional type-I isothermal regime (τmig˜0.01-0.1 Myr), only have a modest effect on the protoplanetary embryos and planetesimals. Sufficient material survives to form rocky, Earth-like planets on orbits exterior to the super-Earths'. In contrast, slowly-migrating super-Earths shepherd rocky material interior to their orbits and strongly deplete the terrestrial planet-forming zone. In this situation any Earth-sized planets in the habitable zone are extremely volatile-rich and are therefore probably not Earth-like.

  11. ILO - International Migration Programme.

    Science.gov (United States)

    Boudraa, Miriam

    2011-01-01

    In a wide International Context characterised not only by the economical development but also by the social, cultural, political and individual development, we witness more and more to a exchange between the developed and the developing countries, which can be translated especially in the migration of the work force. In theory, all countries are either countries of origin either countries of transit or destination, and they are all responsible for the rights of migrant workers by promoting the rights, by monitoring and by preventing the abusive conditions. The process of migration of the workforce can be divided into three stages: the first coincides with the period prior to departure, the second is represented by the aftermath of the departure and the period of stay in the country of destination, the third stage corresponds to the return in the country of origin. The workers must be protected throughout this process by the international organizations that perform the catalytic role of communication and exchange between countries, for the only purpose of protecting the rights of immigrant and/or immigrants workers. The responsibility for the protection of workers is divided among the various players in the International Labour Organisation. Every country has to apply measures according to the international standards regarding workers' rights, standards that guide the various countries in the formulation and implementation of their policies and legislation. These standards are suggested by International Conventions, the ILO Conventions and other international instruments such as the human rights instrument. There has been a big step forward once the ILO Fundamental Conventions and Conventions on Migrant Workers where implemented and this implementation represented the use of the Guidelines "ILO Multilateral Framework on Labour Migration". PMID:22073693

  12. Radioactive caesium contamination due to Fukushima Daiichi Nuclear Power Plants accident in Osaka city. Evaluation of accumulation and decontamination of radioactive materials via reverse logistics function of a city

    International Nuclear Information System (INIS)

    We surveyed background level of radioactive contamination in city area of Osaka before combusting the wide area disposal of disastrous debris at a municipal waste incineration plant of Osaka city. The debris was caused by Tohoku district great earthquake disaster and suspected to be contaminated with radionuclides released from the Fukushima Daiichi Nuclear Power Plants. We also investigated radioactivity in incineration ash of municipal waste incineration plants and of sewage treatment plants, as well as in water clarifier sludge of potable water treatment plants, and evaluated the accumulation and cleansing of radioactive materials via the reverse logistic function of the city. Radioactive caesium deposited in Osaka city area was estimated to be approximately 4.3 GBq from the concentrations observed in the monthly fallout, whereas that collected as municipal wastes and sewage was estimated to be approximately 0.9 GBq a year in 2011. Even two years after the accident, 134Cs, which is the evidence of the Fukushima Daiichi Nuclear Power Plant accident, had been detected in the municipal wastes at a level comparable to the activities found just after the accident, however, the radioactive caesium concentration in fallout measured in the Osaka city area had decreased below a detection limit after May 2012. Introduction of materials contaminated with radioactive caesium from outside the city area was suspected because the observed contamination level was inexplicable by that of observed in the environmental wastes such as pruned branches which are contaminated by with the fallout in city area of Osaka. (author)

  13. Amenity migration and tourism

    Czech Academy of Sciences Publication Activity Database

    Bartoš, Michael; Kušová, Drahomíra; Těšitel, Jan

    Tábor: University of South Bohemia České Budějovice, University of Economics Bratislava, 2005 - (Hesková, M.; Šittler, E.; Dvořák, V.), s. 17-21 ISBN 80-7040-766-2. [Tourism, regional development and education. Sustainable development and tourism. Tábor (CZ), 12.05.2005-13.05.2005] Grant ostatní: EU(XE) European Union/'s Quality of Life and Management of Living Resources programme:QLK5-CT-2000-01211-SPRITE Institutional research plan: CEZ:AV0Z60870520 Keywords : sustainable tourism * amenity migration * regional development Subject RIV: AE - Management ; Administration

  14. [Obesity, migration and adolescence].

    Science.gov (United States)

    Chamay-Weber, Catherine; Shehu-Brovina, Shqipe; Narring, Françoise

    2012-06-13

    Weight management interventions during adolescence are challenging. Migration adds complexity to this problem, making migrant families more vulnerable. Teenagers confront families to new values transmitted by the host society: opulence, junk food, video games. Obesity should not be seen as a single issue of calories-excess, but must be considered as being part of a larger problem, which takes into account the context of the familial and societal life of the migrants. The caregivers must have an overall view of the situation to provide appropriate approaches to weight management. PMID:22787729

  15. Turkish migration in Europe: EU accession and migration flows

    OpenAIRE

    Wadim Strielkowski; Ondřej Glazar

    2014-01-01

    This paper analyses the impact of Turkey's potential EU membership on emigration from Turkey to the European Union. We apply panel data estimators using the data on emigration from EU15 countries into Germany and the Netherlands in order to construct possible future scenarios of Turkish migration to the EU. Three scenarios of migration, pessimistic, realistic and optimistic (depending on the fears related to the expected impact of Turkish migration on the EU labour markets), are drawn and fut...

  16. The migration flux: Understanding international immigration through internal migration

    OpenAIRE

    Rickard Sandell

    2011-01-01

    This paper introduces the idea that the network structure that emerges from a foreign-born population's internal migration process changes the conditions for international immigration. The idea is tested by using data from the period between 1998 and 2008 about virtually all internal and international migration events in Spain. The findings show that internal migration changes the intensity and the quality content of immigrant social capital transfers, with both positive and negative ramifica...

  17. Migration of liquid phase from the primary/peritectic interface in a temperature gradient

    Science.gov (United States)

    Peng, Peng; Li, XinZhong; Su, YanQing; Guo, JingJie

    2016-07-01

    The migration of the liquid droplets from the primary α/peritectic β interface at the peritectic temperature TP has been observed and analyzed in a Sn-Ni peritectic alloy. During the isothermal annealing stage of the interrupted directional solidification, a concentration gradient is established across the liquid droplets along the direction of the temperature gradient due to the temperature gradient zone melting. Simultaneous remelting/resolidification at the top/bottom of the liquid droplets by this concentration gradient have been confirmed to lead to migration of these droplets towards higher temperatures. The dependence of the migration distance of the liquid droplets on isothermal annealing time has been well predicted. Furthermore, since the lengths of the liquid droplet are not uniform along the direction of the temperature gradient, the remelting/resolidification rates which are dependent on the local morphology of liquid droplet are different at different local positions of the liquid droplets. It has been demonstrated that the morphology of the liquid droplet was also influenced by the morphologies of the liquid phase themselves. Therefore, the morphology of the liquid droplet itself changes from spherical to some kinds of irregular shapes during its migration.

  18. Generalized isothermal models with strange equation of state

    Indian Academy of Sciences (India)

    S D Maharaj; S Thirukkanesh

    2009-03-01

    We consider the linear equation of state for matter distributions that may be applied to strange stars with quark matter. In our general approach the compact relativistic body allows for anisotropic pressures in the presence of the electromagnetic field. New exact solutions are found to the Einstein–Maxwell system. A particular case is shown to be regular at the stellar centre. In the isotropic limit we regain the general relativistic isothermal Universe. We show that the mass corresponds to the values obtained previously for quark stars when anisotropy and charge are present.

  19. Modeling of the Adiabatic and Isothermal Methanation Process

    Science.gov (United States)

    Porubova, Jekaterina; Bazbauers, Gatis; Markova, Darja

    2011-01-01

    Increased use of biomass offers one of the ways to reduce anthropogenic impact on the environment. Using various biomass conversion processes, it is possible to obtain different types of fuels: • solid, e.g. bio-carbon; • liquid, e.g. biodiesel and ethanol; • gaseous, e.g. biomethane. Biomethane can be used in the transport and energy sector, and the total methane production efficiency can reach 65%. By modeling adiabatic and isothermal methanation processes, the most effective one from the methane production point of view is defined. Influence of the process parameters on the overall efficiency of the methane production is determined.

  20. Isothermal crystallization kinetic modeling of poly(etherketoneketone) (PEKK)

    Science.gov (United States)

    Choupin, T.; Paris, C.; Cinquin, J.; Fayolle, B.; Régnier, G.

    2016-05-01

    Isothermal melt and cold crystallization kinetics of poly(etherketoneketone) (PEKK) have been investigated by differential scanning calorimetry. A modified Avrami model has been used to describe the two-stage crystallization of PEKK. The primary crystallization stage is assumed to be a two dimensional nucleation growth with an Avrami exponent of 2 whereas the secondary stage is assumed to be a one dimensional nucleation growth with an Avrami exponent of 1. The evolution of the crystallization constant rates depending on temperature has been modeled with the Hoffman and Lauritzen growth equation. The activation energy of nucleation constants Kg for both crystallizations are presented.

  1. Isothermal Melt Crystallization Kinetics of PP/organoclay Blends

    Directory of Open Access Journals (Sweden)

    Wang Kunyan

    2016-01-01

    Full Text Available Polystyrene (PP/organoclay (OMMT blends were prepared by co-rotating twin-screw extruder. The effects of OMMT on isothermal crystallization behaviors of blends was studied by differential scanning calorimetry (DSC. Using Avrami equation analysis the crystallization kinetics of materials. The analysis result shows that the OMMT act as effective nucleating agents, accelerating the crystallization of PP, then lead the rate of crystallization increased. Avrami exponent n is between 2.04~3.57, which indicating that PP/OMMT blends crystallization process might correspond to a two-dimensional or three-dimensional growth process. The activation enerigies for isotheraml crystallization were determined by the Arrhenius equation.

  2. Non-isothermal plasticity model for cyclic behaviour of soils.

    OpenAIRE

    Laloui, L.; Cekerevac, C.

    2008-01-01

    On the one hand, it has been observed that liquefaction- induced shear deformation of soils accumulates in a cycle- by-cycle pattern. On the other hand, it is known that heating could induce plastic hardening. This study deals with the constitutive modelling of the effect that heat may have on the cyclic mechanical properties of cohesive soils, a relatively new area of interest in soil mechanics. In this paper, after a presentation of the thermo-mechanical framework, a non-isothermal pl...

  3. The density variance -- Mach number relation in supersonic, isothermal turbulence

    OpenAIRE

    Price, Daniel J.; Federrath, Christoph; Brunt, Christopher M.

    2010-01-01

    We examine the relation between the density variance and the mean-square Mach number in supersonic, isothermal turbulence, assumed in several recent analytic models of the star formation process. From a series of calculations of supersonic, hydrodynamic turbulence driven using purely solenoidal Fourier modes, we find that the `standard' relationship between the variance in the log of density and the Mach number squared, i.e., sigma^2_(ln rho/rhobar)=ln (1+b^2 M^2), with b = 1/3 is a good fit ...

  4. New Exact Solutions for Isothermal Magnetostatic Atmosphere Equations

    Directory of Open Access Journals (Sweden)

    Mohamed Tawfik ATTIA

    2014-12-01

    Full Text Available Here, an extended, (G'/G-expansion method with a computerized symbolic computation is used for constructing the exact travelling wave solutions for isothermal magnetostatic atmospheres equations. These equations depend on arbitrary functions that must be specified with choices of the different choice of the different arbitrary functions. The proposed method has been successfully used to obtain some exact travelling wave solutions for the Liouville and sinh-Poisson equations. The obtained travelling wave solutions are expressed by hyperbolic, triangular and exponential function. The solutions obtained via the propose method have many potential applications in physics.

  5. Isothermal plasma waves in a gravitomagnetic planar analog

    International Nuclear Information System (INIS)

    We investigate the wave properties of the Kerr black hole with isothermal plasma using 3+1 ADM formalism. The corresponding Fourier-analyzed perturbed GRMHD equations are used to obtain the dispersion relations. These relations lead to the real values of the components of the wave vector k which are used to evaluate quantities such as phase and group velocities etc. These have been discussed graphically in the neighborhood of the pair production region. The results obtained verify the conclusion of Mackay et al according to which rotation of a black hole is required for negative phase velocity propagation

  6. The oxidation kinetics of zircaloy - 4 under isothermal conditions

    International Nuclear Information System (INIS)

    The oxidation kinetics of zircaloy-4 tubes was studied by means of isothermal tests in the temperature interval 5000C to 9000C. Dry oxygen and water steam, were used as oxidant agents. The results show that the oxidation kinetics law exhibits a behaviour from cubic to parabolic in the range of the time and temperatures of the experiment. Dry oxygen shows a stronger oxidation effect than water steam. A special mechanical test to study the embrittlement effect in the small samples of zircaloy tubes was used. (Author)

  7. RuO2 Non-isothermal Thermometry

    Science.gov (United States)

    Ventura, Guglielmo; Giomi, Silvia

    2016-08-01

    The use of a RuO2 resistor in non-isothermal measuring setup is proposed. A calculation is presented to explain the principle for a resistor obeying variable-range-hopping theory and the results are compared to measurements in the range of 11.2-30 mK for a commercial resistor. The thermometer, which measures the electron temperature, does not show overheating effects at 11.2 mK with a measuring power of 10^{-12} W.

  8. The influence of soil properties and local characteristics on the distribution, migration and potential bioavailability of radio-cesium in Bavarian forest ecosystems more than 20 years after the Chernobyl accident

    International Nuclear Information System (INIS)

    Full text: Soil properties and local characteristics of landscapes and ecosystems influence the behaviour of radio-cesium. Humic horizons are a main factor in understanding the migration and potential bioavailability of radio-nuclides in soils. Until 1962 and in the year 1986, nuclear arms tests in the Pacific and the Chernobyl reactor accident emitted persistent radionuclides in the atmosphere that are stored in several European ecosystems. Short-term high as well as long-term low immissions lead to enrichments and increasing contamination of the environment up to superposition effects in certain ecosystems. South German forest ecosystems like the Bavarian Forest or the Northern pre-Alps are subareas of the caesium fallout affected sites after the Chernobyl accident. Cesium-137 is constantly contained in the vegetation and food chain in spite of decreasing local doses. Investigations have shown that the enrichment of caesium is mainly restricted to the organic top layers of the forest soils. Examples of several Bavarian forest ecosystems are given. Horizontal and vertical forest soil distributions of the cesium contamination and its bioavailability were determined to provide a default-document how to act in case of a repetition of a nuclear accident. Such a guideline has been created by order of the Bavarian State Government and its scope is presented here. (author)

  9. Microstructure evolution and deformation mechanisms of the electroslag refined-continuous directionally solidified (ESR-CDS{sup ®}) superalloy Rene88DT during isothermal compression

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Rui [Superalloys Department, Central Iron & Steel Research Institute, Beijing 100081 (China); Li, Fulin, E-mail: lifulin1016@sina.com [Superalloys Department, Central Iron & Steel Research Institute, Beijing 100081 (China); Yin, Fajie; Feng, Di; Tian, Zhiling [Superalloys Department, Central Iron & Steel Research Institute, Beijing 100081 (China); Chang, Litao [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an 710048 (China)

    2015-06-25

    The microstructure evolution and deformation mechanisms of alloy Rene88DT prepared by ESR-CDS{sup ®} during isothermal compression have been investigated by optical microscopy (OM), electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results showed that two cycles of dynamic recrystallization (DRX) occurred during the compressive deformation of the sample at super-solvus temperature with total true strain of 1.2, and this led to a near completely recrystallized fine-grained microstructure. For samples deformed at sub-solvus temperature, only one cycle of DRX occurred during compression with total true strain of 1.2, resulting in a partial recrystallized microstructure, and large misorientation formed in the un-recrystallized coarse grains. DRX is mainly initiated at the columnar grain boundaries or stimulated by the carbide particles within the grains. The main DRX mechanisms are grain boundary bulging and migration, second phase particles stimulation, sub-grain coarsening and migration.

  10. Microstructure evolution and deformation mechanisms of the electroslag refined-continuous directionally solidified (ESR-CDS®) superalloy Rene88DT during isothermal compression

    International Nuclear Information System (INIS)

    The microstructure evolution and deformation mechanisms of alloy Rene88DT prepared by ESR-CDS® during isothermal compression have been investigated by optical microscopy (OM), electron back scattered diffraction (EBSD) and transmission electron microscopy (TEM). The results showed that two cycles of dynamic recrystallization (DRX) occurred during the compressive deformation of the sample at super-solvus temperature with total true strain of 1.2, and this led to a near completely recrystallized fine-grained microstructure. For samples deformed at sub-solvus temperature, only one cycle of DRX occurred during compression with total true strain of 1.2, resulting in a partial recrystallized microstructure, and large misorientation formed in the un-recrystallized coarse grains. DRX is mainly initiated at the columnar grain boundaries or stimulated by the carbide particles within the grains. The main DRX mechanisms are grain boundary bulging and migration, second phase particles stimulation, sub-grain coarsening and migration

  11. Underground radionuclide migration

    International Nuclear Information System (INIS)

    The number 9 sub-report of the safety assesment studies of the disposal of radioactive waste in rock-salt formations concerns the calculation of radio-nuclide migration with groundwater. Calculations ar carried out in two phases. The first phase consists of calculation of the groundwater flow system under a great number of different hydrological boundary conditions, which possibly can be encountered in future. Variations in sea level and consequences of glaciations are included. Given a great number of possible groundwater flow systems, in the second phase radionuclide migration is calculated for a restricted number of representative situations. Transport of radionuclides with groundwater takes place, starting at a release point at the top (edge) of the rock salt formation until the landsurface, the bottom of a sea or an extraction-well for public water supply has been reached, at which places concentrations radionuclides have been computed as a function of time. Calculations continued till all concentrations had reached their maxima. Results form the input for biosphere dose-calculations, as reported in the number 10 sub-report. (author). 26 refs.; 43 figs.; 22 tabs

  12. The challenges of managing migration

    Energy Technology Data Exchange (ETDEWEB)

    Tacoli, Cecilia

    2005-10-15

    Migration and urbanisation are driven by economic growth and social change, but also by deepening inequalities. Managing migration should not be equated with curbing it, as this inevitably reduces migrants' rights. But managing population movement whilst respecting the rights of migrants and nonmigrants, supporting the contribution of migration to poverty reduction and economic growth in sending and receiving areas and reducing the human and material costs of movement means that fundamental challenges need to be addressed.

  13. Modelling Turkish Migration to Germany

    OpenAIRE

    Akkoyunlu, Sule; Siliverstovs, Boriss

    2006-01-01

    This study develops a time series model of Turkish migration to Germany for the period 1963-2004 using the cointegration technique. A single cointegrating relation between the migration flow variable and the relative income ratio between Germany and Turkey, the unemployment rates in Germany and Turkey, and the trade variable, that captures intensity of bilateral economic cooperation, is found. By including the trade variable in the empirical migration function we investigate whether trade and...

  14. Migration and the Demographic Shift

    OpenAIRE

    Zaiceva, Anzelika; Zimmermann, Klaus F.

    2014-01-01

    This chapter connects population aging with international migration. After documenting the trends for both, we review the supply-push and demand-pull determinants of migration, focusing particularly on the role of age and aging. We subsequently discuss the literature concerning the implications of migration in the context of aging for labor markets, health and public budgets including the political economy context. Although immigration is sometimes suggested as a solution for the aging proble...

  15. Gender and Migration: Overview Report

    OpenAIRE

    Jolly, Susie; Reeves, Hazel; Piper, Nicola

    2005-01-01

    Abstract. Over the past four decades total numbers of international migrants have more than doubled but the percentage of the world population migrating has remained fairly constant. There are now 175 million international migrants worldwide or approximately 3.5 per cent of the global population – about half of whom are women, despite the common misconception that men are the migrants. This Overview Report on Gender and Migration takes a broad approach to migration – it looks at the gender dy...

  16. 3D Finite Element Analysis of Spider Non-isothermal Forging Process

    Science.gov (United States)

    Niu, Ling; Wei, Wei; Wei, Kun Xia; Alexandrov, Igor V.; Hu, Jing

    2016-06-01

    The differences of effective stress, effective strain, velocity field, and the load-time curves between the spider isothermal and non-isothermal forging processes are investigated by making full use of 3D FEA, and verified by the production experiment of spider forging. Effective stress is mainly concentrated on the pin, and becomes lower closer to the front of the pin. The maximum effective strain in the non-isothermal forging is lower than that in the isothermal. The great majority of strain in the non-isothermal forging process is 1.76, which is larger than the strain of 1.31 in the isothermal forging. The maximum load required in the isothermal forging is higher than that in the non-isothermal. The maximum experimental load and deformation temperature in the spider production are in good agreement with those in the non-isothermal FEA. The results indicate that the non-isothermal 3D FEA results can guide the design of the spider forging process.

  17. Thermistor based, low velocity isothermal, air flow sensor

    International Nuclear Information System (INIS)

    The semiconductor thermistor technology is applied as a flow sensor to measure low isothermal air velocities (<2 ms−1). The sensor is subjected to heating and cooling cycles controlled by a multifunctional timer. In the heating stage, the alternating current of a main AC power supply source guarantees a uniform thermistor temperature distribution. The conditioning circuit assures an adequate increase of the sensors temperature and avoids the thermal disturbance of the flow. The power supply interruption reduces the consumption from the source and extends the sensors life time. In the cooling stage, the resistance variation of the flow sensor is recorded by the measuring chain. The resistive sensor parameters proposed vary significantly and feature a high sensitivity to the flow velocity. With the aid of a computer, the data transfer, storage and analysis provides a great advantage over the traditional local anemometer readings. The data acquisition chain has a good repeatability and low standard uncertainties. The proposed method measures isothermal air mean velocities from 0.1 ms−1 to 2 ms−1 with a standard uncertainty error less than 4%. (paper)

  18. Isothermal behaviour of a Gloetzl in the HAW test field

    International Nuclear Information System (INIS)

    The HAW test field in the Asse mine (Germany) is a one-to-one scale test facility of an underground repository. One objective of the HAW project is to measure thermally induced stresses and deformation fields in the surrounding rock. Many measuring instruments have been placed in specially drilled holes at various locations to measure pressure change in the test field. One of the types used is the so-called 'Gloetzl' pressure cell. The measuring result of a 'Gloetzl' is a combination of pressure build-up as result of local borehole deformation due to creep and stress changes due to changes in the global field around the measuring borehole. Especially in the isothermal and low temperature situation results are dominated by this local borehole deformation. To understand the measuring results of a 'Gloetzl' better an analysis had been performed in which time-dependent (isothermal) behaviour of the measuring hole is investigated using a finite element program. Delay between borehole drilling and final emplacement of the device into the borehole is varied. From the results it can be obtained that the time between drilling of the hole and 'Gloetzl'-emplacement influences the pressure result for a very long period of time and the recuperation to the boundary stresses needs more than 300 years. Thus, the measuring results of the 'Gloetzls' can not be considered to represent directly the stresses in the field. The behaviour under heated conditions needs more detailed analyses. (author). 2 refs.; 9 figs

  19. Laser velocimetry measurements in non-isothermal CVD systems

    Science.gov (United States)

    Johnson, E. J.; Hyer, P. V.; Culotta, P. W.; Clark, I. O.

    1991-01-01

    Researchers at the NASA Langley Research Center are applying laser velocimetry (LV) techniques to characterize the fluid dynamics of non-isothermal flows inside fused silica chambers designed for chemical vapor deposition (CVD). Experimental issues involved in the application of LV techniques to this task include thermophoretic effects on the LV seed particles, seeding the hazardous gases, index of refraction gradients in the flow field and surrounding media, optical access, relatively low flow velocities, and analysis and presentation of sparse data. An overview of the practical difficulties these issues represent to the use of laser velocimetry instrumentation for CVD applications is given. A fundamental limitation on the application of LV techniques in non-isothermal systems is addressed which involves a measurement bias due to the presence of thermal gradients. This bias results from thermophoretic effects which cause seed particle trajectories to deviate from gas streamlines. Data from a research CVD reactor are presented which indicate that current models for the interaction of forces such as Stokes drag, inertia, gravity, and thermophoresis are not adequate to predict thermophoretic effects on particle-based velocimetry measurements in arbitrary flow configurations.

  20. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot

    Directory of Open Access Journals (Sweden)

    R. Prasad

    2011-01-01

    Full Text Available To comply with the stringent emission regulations on soot, diesel vehicles manufacturers more and more commonly use diesel particulate filters (DPF. These systems need to be regenerated periodically by burning soot that has been accumulated during the loading of the DPF. Design of the DPF requires rate of soot oxidation. This paper describes the kinetics of catalytic oxidation of diesel soot with air under isothermal conditions. Kinetics data were collected in a specially designed mini-semi-batch reactor. Under the high air flow rate assuming pseudo first order reaction the activation energy of soot oxidation was found to be, Ea = 160 kJ/ mol. ©2010 BCREC UNDIP. All rights reserved(Received: 14th June 2010, Revised: 18th July 2010, Accepted: 9th August 2010[How to Cite: R. Prasad, V.R. Bella. (2010. Isothermal Kinetics of Catalyzed Air Oxidation of Diesel Soot. Bulletin of Chemical Reaction Engineering and Catalysis, 5(2: 95-101. doi:10.9767/bcrec.5.2.796.95-101][DOI:http://dx.doi.org/10.9767/bcrec.5.2.796.95-101 || or local:  http://ejournal.undip.ac.id/index.php/bcrec/article/view/796]Cited by in: ACS 1 |

  1. A New Potential-Density Pair for Isothermal Star Clusters

    CERN Document Server

    Stone, Nicholas C

    2015-01-01

    We present a new potential-density pair designed to model nearly isothermal star clusters (and similar self-gravitating systems) with a central core and an outer turnover radius, beyond which density falls off as $r^{-4}$. In the intermediate zone, the profile is similar to that of an isothermal sphere (density $\\rho \\propto r^{-2}$), somewhat less steep than the King 1962 profile, and with the advantage that many dynamical quantities can be written in a simple closed form. We derive analytic expressions for the cluster binding energy, central velocity dispersion, and escape velocity, and apply these to create toy models for cluster core collapse and evaporation. We rederive classical results for evaporating, collapsing, and quasi-equilibrium (heated) clusters, and fit our projected surface brightness profiles to observed globular and open clusters. We find that the quality of the fit is generally at least as good as that for the surface brightness profiles of King 1962. This model can be used for convenient ...

  2. Thermal cycling and isothermal tests on black-coated specimens

    International Nuclear Information System (INIS)

    Thermal cycling and isothermal tests were performed on AISI 316 L(N) austenitic steel with different types of black coating. The adhesion and the fatigue life of the coatings, as well as the fatigue of the base material were investigated. The tests were performed in different test rigs, using tubes and circular discs. The discs were subjected to cyclic heating on the coated side, using an Ar+He+1%H2 flame in a plasma spray facility. The tubes, coated on the outside, were induction heated. The temperature ranges typical for first wall applications were about 150-430 C on the discs and 80-435 C for the tubes. Isothermal strain-controlled uniaxial tests on coated tubes have been carried out as a base comparison for the thermal cycling experiments. In this report, the test rigs are described and the results of the tests are presented. For the tubes, the adhesion of the coatings up to high loadings was surprisingly good. Likewise, no accelerated fatigue of the base material was observed to be caused by the coatings. For the discs, nearly all the coatings survived 10000 load cycles. (orig.)

  3. Isothermal decomposition kinetics of nickel (II) hydroxide powder

    Energy Technology Data Exchange (ETDEWEB)

    Carney, C.S., E-mail: Casey.Carney@CONTR.NETL.DOE.GOV [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States); Chinn, R.E.; Doğan, Ö.N. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); Gao, M.C. [National Energy Technology Laboratory, U.S. Dept. of Energy, Albany, OR (United States); AECOM, P.O. Box 1959, Albany, OR (United States)

    2015-09-25

    Highlights: • A first order random nucleation model was proposed for the decomposition of nickel hydroxide. • Trapped lattice product water greatly suppressed high conversion reaction rates. • Annealing experiments of the Ni–Ni(OH){sub 2}–NiO phase triangle yielded only two phases: Ni and NiO. • This Ni–Ni(OH){sub 2}–NiO phase triangle in the Ni-rich corner of the Ni–O–H system was confirmed. - Abstract: Nickel (II) hydroxide powder was investigated by thermogravimetry for isothermal decomposition kinetics and verification of the Ni–O–H ternary phase diagram at low temperatures. The activation energy and frequency factor were measured as E{sub a} = 134 kJ/mol and A = 1.27 × 10{sup 10} s{sup −1}, respectively. The validity of the first-order random nucleation model was confirmed, as opposed to diffusion and or moving-boundary models. The dependence of TGA results on specimen size was noted. The Ni–Ni(OH){sub 2}–NiO phase triangle was confirmed. Accordingly, a thermodynamic description of the system was established in the Ni-rich corner, and the isotherm at room temperature is calculated.

  4. Estimating Uranium Partition Coefficients from Laboratory Adsorption Isotherms

    International Nuclear Information System (INIS)

    An estimated 330 metric tons of uranium have been buried in the radioactive waste Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). An assessment of uranium transport parameters is being performed to decrease the uncertainty in risk and dose predictions derived from computer simulations of uranium fate and transport to the underlying Snake River Plain Aquifer. Uranium adsorption isotherms have been measured in the laboratory and fit with a Freundlich isotherm. The Freundlich n parameter was statistically identical for 14 sediment samples. The Freundlich Kf for seven samples, where material properties have been measured, is correlated to sediment surface area. Based on these empirical observations, a model has been derived for adsorption of uranium on INEEL sedimentary materials using surface complexation theory. The model was then used to predict the range of adsorption conditions to be expected at the SDA. Adsorption in the deep vadose zone is predicted to be stronger than in near-surface sediments because the total dissolved carbonate decreases with depth

  5. Isothermal titration calorimetry: A thermodynamic interpretation of measurements

    International Nuclear Information System (INIS)

    Highlights: ► Literature review shows that many ITC utilizations are based on empirical rules. ► A proper and rigorous thermodynamic interpretation of heats of titration is proposed. ► Heats of titration are independent of the cell type using infinitesimal titrations. ► Heats of interaction between solutes require only two different titration runs. - Abstract: Isothermal titration calorimeters have been developed and in use since the 1960s and the number of applications based on empirical rules to use them steadily increases. In this paper a rigorous study of the physical interpretation of the titration heat and the thermodynamic framework underlying isothermal titration calorimetry are proposed. For infinitesimal titrations, the titration heat is independent of the cell type employed, and the interpretation of the titration heat depends on the titrant composition and on the experiment type. Moreover, for the study of the interaction between two solutes in solution, only a combination of two experiments is necessary, and the result is interpreted as the partial enthalpy of interaction at infinite dilution of the solute contained in the titrant solution.

  6. Bondi-like Accretion in Magnetized Supersonic Isothermal Turbulence

    Science.gov (United States)

    Burleigh, Kaylan J.; McKee, Christopher F.; Klein, Richard I.

    2016-01-01

    The Bondi and Bondi-Hoyle-Lytlleton formulas give the order of magnitude steady-accretion rate onto a point mass at rest or moving, respectively, in a uniform density gas in the limit of negligible gas self-gravity. This applies in star-forming clouds where self-gravity is negligible near protostars and new-born stars, but instead of being uniform the gas is supersonically turbulent and threaded by dynamically important (Alven Mach number ˜ 1) large-scale magnetic fields. To determine the Bondi-like accretion rate in these environments, we used the ORION2 code to carry out grid-based 3D adaptive mesh refinement (AMR) magnetohydrodynamic (MHD) simulations of accretion onto sink particles embedded in an environment of fully developed, magnetized supersonic isothermal turbulence. We evolved the models until the median and mean accretion rates, over particles, became steady. We present a simple semi-analytic model that predicts the median and mean accretion rate from the turbulent properties of the background medium, such as the 3D Mach number and RMS plasma-β, and show that it is highly consistent with our simulations. Numerical codes can use our semi-analytic model as an accurate sub-grid model for accretion in magnetized supersonic isothermal turbulence.

  7. Dynamic Evolution Model of Isothermal Voids and Shocks

    CERN Document Server

    Lou, Yu-Qing

    2009-01-01

    We explore self-similar hydrodynamic evolution of central voids embedded in an isothermal gas of spherical symmetry under the self-gravity. More specifically, we study voids expanding at constant radial speeds in an isothermal gas and construct all types of possible void solutions without or with shocks in surrounding envelopes. We examine properties of void boundaries and outer envelopes. Voids without shocks are all bounded by overdense shells and either inflows or outflows in the outer envelope may occur. These solutions, referred to as type $\\mathcal{X}$ void solutions, are further divided into subtypes $\\mathcal{X}_{\\rm I}$ and $\\mathcal{X}_{\\rm II}$ according to their characteristic behaviours across the sonic critical line (SCL). Void solutions with shocks in envelopes are referred to as type $\\mathcal{Z}$ voids and can have both dense and quasi-smooth edges. Asymptotically, outflows, breezes, inflows, accretions and static outer envelopes may all surround such type $\\mathcal{Z}$ voids. Both cases of c...

  8. A microfabrication-based approach to quantitative isothermal titration calorimetry.

    Science.gov (United States)

    Wang, Bin; Jia, Yuan; Lin, Qiao

    2016-04-15

    Isothermal titration calorimetry (ITC) directly measures heat evolved in a chemical reaction to determine equilibrium binding properties of biomolecular systems. Conventional ITC instruments are expensive, use complicated design and construction, and require long analysis times. Microfabricated calorimetric devices are promising, although they have yet to allow accurate, quantitative ITC measurements of biochemical reactions. This paper presents a microfabrication-based approach to integrated, quantitative ITC characterization of biomolecular interactions. The approach integrates microfabricated differential calorimetric sensors with microfluidic titration. Biomolecules and reagents are introduced at each of a series of molar ratios, mixed, and allowed to react. The reaction thermal power is differentially measured, and used to determine the thermodynamic profile of the biomolecular interactions. Implemented in a microdevice featuring thermally isolated, well-defined reaction volumes with minimized fluid evaporation as well as highly sensitive thermoelectric sensing, the approach enables accurate and quantitative ITC measurements of protein-ligand interactions under different isothermal conditions. Using the approach, we demonstrate ITC characterization of the binding of 18-Crown-6 with barium chloride, and the binding of ribonuclease A with cytidine 2'-monophosphate within reaction volumes of approximately 0.7 µL and at concentrations down to 2mM. For each binding system, the ITC measurements were completed with considerably reduced analysis times and material consumption, and yielded a complete thermodynamic profile of the molecular interaction in agreement with published data. This demonstrates the potential usefulness of our approach for biomolecular characterization in biomedical applications. PMID:26655185

  9. Obtaining a TRIP microstructure by thermomechanical treatment without isothermal holding

    Science.gov (United States)

    Masek, B.; Jirkova, H.; Kucerova, L.; F-X Wagner, M.

    2016-03-01

    The contemporary development of technological processes for the production of modern multiphase steels can be characterized by the need for precise control of their technological parameters. The design of modern technological processes that allow sophisticated microstructures to be obtained usually cannot be carried out on real production equipment for technical as well as economical reasons. Therefore, new processes and test devices are continuously being developed to make it possible to simulate and model thermomechanical treatments on small specimens with precise control and monitoring of process parameters. A simulator for experimental modelling of thermomechanical processes has been developed at the University of West Bohemia. In this paper, to demonstrate the feasibility of simulating thermomechanical treatments with this setup on a lab scale, we discuss the thermomechanical treatment of TRIP steels without isothermal holding - a processing route that is difficult to handle and thus poses several technological as well as economic problems. The realistic processing of wire rolling with different cooling strategies is tested on the TRIP CMnSiNb steel. Our results show that the processing route without isothermal holding allows to obtain multiphase microstructures with a tensile strength of up to 835 MPa and a ductility A5mm = 25%.

  10. Crystallographic orientation variation of isothermal pearlite under high magnetic field

    International Nuclear Information System (INIS)

    Crystallographic orientation (CO) variation of magnetic-induced pearlite (MIP) during its microstructure evolution in 19.8 T was investigated by electron back-scatter diffraction (EBSD). It is closely related to the isothermal temperatures (ITs) and the applied magnetic time (MT) during the process of MIP formation. The <100> easy magnetization direction in MIP colonies is strengthened with the MT within the certain transformed fraction of MIP (fMIP) at the relatively lower IT (983 K) above the eutectoid temperature but below the magnetically shifted upward eutectoid temperature, while this special CO tends to be weakened at a relatively higher IT (995 K). For the same MT, the higher the IT, the relatively larger is the proportion in <100> orientation for MIP colonies at the early growth stage. These results have demonstrated that the change of <100> orientation of MIP is closely related to the growth rate of pearlite ferrite (PF), and strengthened mainly at early transformation stage. When fMIP reaches some value, the growth rate of MIP at other COs, such as <110>, even at the hard magnetization direction, turns to present speed-up. - Highlights: • HMF can induce pearlite with different fractions above the eutectoid temperature. • CO is closely related to isothermal temperatures and applied magnetic time. • <100> direction is related to the growth rate of PF, and strengthened at early stage. • When fMIP reaches some value, the growth rate at other COs turns to present speed-up

  11. The Migration of Highly Skilled Asian Workers

    OpenAIRE

    Horáková, Jana

    2012-01-01

    This thesis is focused on migration of highly skilled workforce. The aim of this work to show current migration flows of highly skilled workers and particularly flows of highly skilled Asian migrants. First chapter explains migration terms and examines highly skilled migration causes through migration theories. Second chapter studies international migration flows and their long-term development. Last chapter is focused on migration flows of highly skilled Asians to OECD countries and within A...

  12. Amenity migration as an example of the environmental migration

    Czech Academy of Sciences Publication Activity Database

    Bartoš, Michael; Kušová, Drahomíra; Těšitel, Jan

    Newcastle upon Tyne: Cambridge Scholars Publishing, 2008, s. 58-75. ISBN 978-1-4438-0038-9 R&D Projects: GA ČR(CZ) GA403/07/0714 Institutional research plan: CEZ:AV0Z60870520 Keywords : amenity migration * environmental migration * local development Subject RIV: AO - Socio logy, Demography

  13. Effects of fluvial processes in different order river valleys on redistribution and storage of particle-bound radioactive caesium-137 in area of significant Chernobyl fallout and impact on linked rivers with lower contamination levels

    Science.gov (United States)

    Belyaev, Vladimir; Golosov, Valentin; Shamshurina, Evgeniya; Ivanov, Maxim; Ivanova, Nadezhda; Bezukhov, Dmitry; Onda, Yuichi; Wakiyama, Yoshifumi; Evrard, Olivier

    2015-04-01

    Detailed investigations of the post-fallout fate of radionuclide contamination represent an important task in terms of environmental quality assessment. In addition, particle-bound radionuclides such as the most widespread anthropogenic isotope caesium-137 can be used as tracers for quantitative assessment of different sediment redistribution processes. In landscapes of humid plains with agriculture-dominated land use the post-fallout redistribution of caesium-137 is primarily associated with fluvial activity of various scales in cascade systems starting from soil erosion on cultivated hillslopes through gully and small dry valley network into different order perennial streams and rivers. Our investigations in the so-called Plavsk hotspot (area of very high Chernobyl caesium-137 contamination within the Plava River basin, Tula Region, Central European Russia) has been continuing for more than 15 years by now, while the time passed since the Chernobyl disaster and associated radioactive fallout (1986) is almost 29 years. Detailed information on the fluvial sediment and associated caesium-137 redistribution has been obtained for case study sites of different size from individual cultivated slopes and small catchments of different size (2-180 km2) to the entire Plava River basin scale (1856 km2). It has been shown that most of the contaminated sediment over the time passed since the fallout has remained stored within the small dry valleys of the 1-4 Hortonian order and local reservoirs (>70%), while only about 5% reached the 5-6 order valleys (main tributaries of the Plava River) and storage of the Plava floodplain itself represents as low as 0.3% of the basin-scale total sediment production from eroded cultivated hillslopes. Nevertheless, it has been shown that contaminated sediment yield from the Plava River basin exerts significant influence on less polluted downstream-linked river system. Recent progress of the investigations involved sampling of 7 detailed depth

  14. Patterns of East to West migration in the context of European migration systems possibilities and limits of migration control

    OpenAIRE

    Irina Molodikova

    2008-01-01

    This paper gives an overview of the main migration trends of the CIS (Commonwealth of Independent States) migration system in the context of the development of EU migration and migration control and seeks to explain the peculiarities of the CIS migration system’s development.

  15. Migration and women's health.

    Science.gov (United States)

    Adanu, Richard M K; Johnson, Timothy R B

    2009-08-01

    Women have been migrating at similar rates to men for the past 40 years, and comprised about half of all migrants in 2005. Women and children are most affected by displacement as a result of wars and human trafficking. In some cases, the health of female migrants is improved via integration into better health systems in the host country. More often, however, the health of female migrants is affected negatively. Women are doubly disadvantaged because they are discriminated against as women and as migrants. Female migrants are also highly vulnerable to acts of sexual abuse, rape, and violence. This is especially true for women in refugee camps, whose reproductive health needs are often overlooked. To improve the health of female migrants it is important to develop and implement policies that recognize and insist on the respect of the rights of migrants. PMID:19539929

  16. Migration - utopia or myopia?

    Directory of Open Access Journals (Sweden)

    Peter Osborne

    1998-03-01

    Full Text Available Peter Osborne spent a sabbatical in northern America and was surprised that so many scientists and students stated that caribou migration was largely the result of mosquito pressure. He failed however to find any documented evidence of this claim although he was constantly confronted by the well known «facts» that mosquitoes had been observed to drive caribou crazy and even kill juveniles. The issue Osborne wishes to focus is that an experimentally unsubstantiated anthropomorphism appears to have become critical evidence in support of a theory. A recent article in Nature (393, 511-513, 1998 devoted to the uses of 'science in fiction' to stimulate thought and discussion about aspects of academia encouraged him to write the following comment in the form of a parody of ancient Greek dialogues.

  17. Nightly Test system migration

    CERN Document Server

    Win-Lime, Kevin

    2013-01-01

    The summer student program allows students to participate to the Cern adventure. They can follow several interesting lectures about particle science and participate to the experiment work. As a summer student, I had worked for LHCb experiment. LHCb uses a lot of software to analyze its data. All this software is organized in packages and projects. They are built and tested during the night using an automated system and the results are displayed on a web interface. Actually, LHCb is changing this system. It is looking for a replacement candidate. So I was charged to unify some internal interfaces to permit a swift migration. In this document, I will describe shortly the system used by LHCb, then I will explain what I have done in detail.

  18. Microstructural evolution during isothermal aging and strain-induced transformation followed by isothermal aging in Co-Cr-Mo-C alloy: A comparative study

    International Nuclear Information System (INIS)

    The present study was undertaken to investigate the effects of isothermal aging (at 850 deg. C for 4, 8, 16 and 24 h) and strain-induced transformation (engineering strains of 10% and 20%) followed by isothermal aging (at 850 deg. C for 4, 8 and 16 h) on the microstructural evolution of a Co-28Cr-5Mo-0.3C alloy. The obtained results showed that isothermal aging at 850 deg. C resulted in the formation of lamellar-type carbides at the grain boundaries. Moreover, X-ray diffraction analysis indicated that isothermal aging of solution treated specimens at 850 deg. C for 24 h did not lead to complete fcc phase transformation to hcp one. In contrast with the isothermally aged specimens, applying plastic deformation to the solutionized samples accelerated the completion and saturation of fcc(metastable) → hcp transformation after 8 h aging at 850 deg. C. In addition, the X-ray diffraction results indicated that implementing isothermal aging of the strain-induced specimens at the higher aging time (16 h) caused the formation of (1 1 1)fcc and (2 0 0)fcc diffraction peaks again. Also, the strain-induced specimens followed by isothermal aging showed higher amount of microhardness as compared with the other specimens aged solely.

  19. Growth behaviors of intermetallic compounds at Sn–3Ag–0.5Cu/Cu interface during isothermal and non-isothermal aging

    International Nuclear Information System (INIS)

    Highlights: •During isothermal aging, the growth rate of Cu6Sn5 is lower than that of Cu3Sn. •For non-isothermal aging, it is Cu6Sn5 that contributes more to the growth of IMC layer than Cu3Sn. •Re-crystallization of solder alloy during non-isothermal aging results in faster growth of IMC layer compared with isothermal aging. •During thermal shock, the growth rate of IMC layer might be slowed down by the propagation of cracks. -- Abstract: The morphology and growth mechanism of intermetallic compound (IMC) layer at Sn–3Ag–0.5Cu/Cu interface during isothermal aging, thermal cycling and thermal shock were investigated in this study by microstructural observations and phase analysis. The results showed that the IMC layer flattened with aging duration because the grooves in scallop-like IMC provide a more convenient access for Cu atoms to dissolve and react with solders and previous IMCs. When isothermal aging was subjected, the growth rate of Cu6Sn5 was lower than that of Cu3Sn. While for thermal cycling, it was Cu6Sn5 that contributed much to the growth of IMC layer. This had much to do with abundant supply of Sn and Cu atoms at the interface of solder/Cu6Sn5 caused by recrystallization of solder and compression stress during thermal cycling. Growth mechanisms of total IMC layer both during isothermal and non-isothermal aging are stated as empirical power-law relationship by using an equivalent aging time parameter. And the growth time exponent depended on the evolution of grain structures of solder matrix, thermal stress and propagation of cracks during non-isothermal conditions

  20. Progress report on a filed study of soil-to-plant transfer of radioactive caesium, strontium and zinc in tropical Northern Australia

    International Nuclear Information System (INIS)

    This report covers: background, study location, design and rationale, farming practice and application, climate monitoring, summaries of the results of chemical analyses, gamma spectrometry and other analyses performed on plants and soil samples and calculation of transfer factors. Comparison with data from the literature, and a brief discussion of the results and implications for the on-going study are also presented. A detailed evaluation of the results has not been performed at this stage as the study is in progress.The main general observations to date are as follows. Transfer factors for caesium (Cs) and strontium (Sr) are not substantially different from the expected values based on the earlier studies mainly within temperate climates. In contrast, the values for zinc (Zn) are more than an order of magnitude greater than anticipated. Most of the radioactivity added to the soils has been retained in the top 5 cm of both soils. There has been a general decline in decay-corrected radioactivity in soils but also an indication of increased heterogeneity in surface distribution. Additional sampling will be undertaken to address this issue

  1. Sensitivity of the modelled deposition of Caesium-137 from the Fukushima Dai-ichi nuclear power plant to the wet deposition parameterisation in NAME

    International Nuclear Information System (INIS)

    This paper describes an investigation into the impact of different meteorological data sets and different wet scavenging coefficients on the model predictions of radionuclide deposits following the accident at the Fukushima Dai-ichi nuclear power plant in March 2011. Three separate operational meteorological data sets, the UK Met Office global meteorology, the ECMWF global meteorology and the Japan Meteorological Agency (JMA) mesoscale meteorology as well as radar rainfall analyses from JMA were all used as inputs to the UK Met Office's dispersion model NAME (the Numerical Atmospheric-dispersion Modelling Environment). The model predictions of Caesium-137 deposits based on these meteorological models all showed good agreement with observations of deposits made in eastern Japan with correlation coefficients ranging from 0.44 to 0.80. Unexpectedly the NAME run using radar rainfall data had a lower correlation coefficient (R = 0.66), when compared to observations, than the run using the JMA mesoscale model rainfall (R = 0.76) or the run using ECMWF met data (R = 0.80). Additionally the impact of modifying the wet scavenging coefficients used in the parameterisation of wet deposition was investigated. The results showed that modifying the scavenging parameters had a similar impact to modifying the driving meteorology on the rank calculated from comparing the modelled and observed deposition

  2. Accumulation of potassium, rubidium and caesium (133Cs and 137Cs) in various fractions of soil and fungi in a Swedish forest

    International Nuclear Information System (INIS)

    Radiocaesium (137Cs) was widely deposited over large areas of forest in Sweden as a result of the Chernobyl accident in 1986 and many people in Sweden eat wild fungi and game obtained from these contaminated forests. In terms of radioisotope accumulation in the food chain, it is well known that fungal sporocarps efficiently accumulate radiocaesium (137Cs), as well as the alkali metals potassium (K), rubidium (Rb) and caesium (Cs). The fungi then enhance uptake of these elements into host plants. This study compared the accumulation of these three alkali metals in bulk soil, rhizosphere, soil-root interface, fungal mycelium and sporocarps of mycorrhizal fungi in a Swedish forest. The soil-root interface was found to be distinctly enriched in K and Rb compared with the bulk soil. Potassium concentrations increased in the order: bulk soil 137Cs could be prevented by providing additional Rb or K at contaminated sites. The levels of K, Rb, and Cs found in sporocarps were at least one order of magnitude higher than those in fungal mycelium. These results provide new insights into the use of transfer factors or concentration ratios. The final step, the transfer of alkali metals from fungal mycelium to sporocarps, raised some specific questions about possible mechanisms.

  3. Rapid and Fully-Automated Measurement of Water Vapor Sorption Isotherms

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Tuller, Markus; Møldrup, Per;

    2014-01-01

    measured isotherms, and ideas for further research in various vadose zone areas including water repellency, contaminant volatilization, and hysteresis are proposed. Eminent environmental challenges such as remediation of contaminated sites, the establishment and maintenance of nuclear waste repositories...... research. Detailed vapor sorption isotherms for 25 variably textured soils were measured with the VSA within 1 to 3 d. Links between generated isotherms and pesticide volatilization, toxic organic vapor sorption kinetics, and soil water repellency are illustrated. Several methods to quantify hysteresis...

  4. On the Helmholtz Potential metric: The Isotherm Length-Work Theorem

    OpenAIRE

    Santoro, Manuel

    2004-01-01

    In this paper we introduce the Isotherm Length-Work theorem using the Helmholtz potential metric and the virial expansion of pressure in inverse power of molar volume. The theorem tells us what length of a thermodynamical system described by equation of state through virial expansion along isotherms actually is with such a metric. We also give explicit solutions for thermodynamic length along isotherms in the case of first, second and third order expansion.

  5. Migrating foreign body from hypopharynx

    DEFF Research Database (Denmark)

    Mowinckel, Marius Storm; Charabi, Birgitte Wittenborg

    2014-01-01

    In this case report we present a 20-month-old girl with a migrating foreign body, a "smiley" sticker, that migrated from hypopharynx to surrounding tissue and created an abscess with a fistula, one year after ingestion. The foreign body was removed without difficulty under general anaesthesia, and...

  6. Migration in birds and fishes

    NARCIS (Netherlands)

    Verwey, J.

    1949-01-01

    Our knowledge concerning the periodical movements in animals called migrations is chiefly based on observations on birds. By and by, however, a number of facts concerning migration in other animal groups have been assembled and it seems worth while to compare them with those known for birds. There i

  7. Software Engineering Challenges of Migration Projects

    Directory of Open Access Journals (Sweden)

    S.Geetha

    2012-03-01

    Full Text Available Organisations often face the challenges of migration from legacy systems to new target systems. Such migration efforts represent a complex engineering problem. This paper describes migration planning, identifies influencing factors, outlines a set of migration planning activities and offers a set of guidelines for the migration planning

  8. Software Engineering Challenges of Migration Projects

    OpenAIRE

    Geetha, S.; Dr.Alagaramy

    2012-01-01

    Organisations often face the challenges of migration from legacy systems to new target systems. Such migration efforts represent a complex engineering problem. This paper describes migration planning, identifies influencing factors, outlines a set of migration planning activities and offers a set of guidelines for the migration planning

  9. Data Migration for Ontology Evolution

    Institute of Scientific and Technical Information of China (English)

    赵彦; 张雷; 林晨曦; 张卓; 俞勇

    2004-01-01

    Ontology is the conceptual backbone that provides meaning to data on the semantic web. However, ontology is not a static resource and may evolve over time, which often leaves the meaning of data in an undefined or inconsistent state. It is thus very important to have a method to preserve the data and its meaning when ontology changes. This paper proposed a general method that solves the problem using data migration. It analyzed some of the issues in the method including separation of ontology and data, migration specification, migration result and migration algorithm. The paper also instantiates the general mothod in RDF(S) as an example. The RDF(S) example itself is a simple but complete method for migrating RDF data when RDFS ontology changes.

  10. Ocean dynamic processes causing spatially heterogeneous distribution of sedimentary caesium-137 massively released from the Fukushima Daiichi Nuclear Power Plant

    Science.gov (United States)

    Higashi, H.; Morino, Y.; Furuichi, N.; Ohara, T.

    2015-12-01

    Massive amounts of anthropogenic radiocaesium 137Cs that were released into the environment by the Fukushima Daiichi Nuclear Power Plant accident in March 2011 are widely known to have extensively migrated to Pacific Ocean sediment off of eastern Japan. Several recent reports have stated that the sedimentary 137Cs is now stable with a remarkably heterogeneous distribution. The present study elucidates ocean dynamic processes causing this heterogeneous sedimentary 137Cs distribution in and around the shelf off Fukushima and adjacent prefectures. We performed a numerical simulation of oceanic 137Cs behaviour for about 10 months after the accident, using a comprehensive dynamic model involving advection-diffusion transport in seawater, adsorption and desorption to and from particulate matter, sedimentation and suspension on and from the bottom, and vertical diffusion transport in the sediment. A notable simulated result was that the sedimentary 137Cs significantly accumulated in a swath just offshore of the shelf break (along the 50-100 m isobath) as in recent observations, although the seabed in the entire simulation domain was assumed to have ideal properties such as identical bulk density, uniform porosity, and aggregation of particles with a single grain diameter. This result indicated that the heterogeneous sedimentary 137Cs distribution was not necessarily a result of the spatial distribution of 137Cs sediment adsorptivity. The present simulation suggests that the shape of the swath is mainly associated with spatiotemporal variation between bottom shear stress in the shallow shelf (simulation indicated that strong bottom friction suspending particulate matter from the seabed frequently occurred via a periodic spring tide about every 2 weeks and via occasional strong wind. The sedimentary 137Cs thereby could hardly stay on the surface of the seabed with the result that the simulated sediment-surface 137Cs activity tended to decrease steadily for a long term after

  11. Experimental and simulated propene isotherms on porous solids

    Science.gov (United States)

    Navarro, M. V.; Puértolas, B.; García, T.; Murillo, R.; Mastral, A. M.; Varela-Gandía, F. J.; Lozano-Castelló, D.; Cazorla-Amorós, D.; Bueno-López, A.

    2010-06-01

    The lack of treatment capacity of hydrocarbons by three-way catalysts during the "cold start" period creates an important environmental problem. During this period, the temperature of the three-way catalyst is too low for effective operation and cannot convert the hydrocarbons in the exhaust. 50-80% of the total hydrocarbon emissions are produced in this phase that accomplishes the first 60-120 s of the engine operation. In this study, the technology chosen to treat these emissions is the use of HC-traps, and molecular simulations are tested as a tool to reproduce the experimental adsorption behaviour of porous solids. Therefore, experimental and simulated adsorption isotherms of propene (model hydrocarbon) have been obtained for four different crystalline materials with distinctive framework structures (3D and 1D) and a variety of Si/Al ratios and cations (three zeolites: ZSM-5, BETA and Mordenite; and a silicoaluminophosphate molecular sieve: SAPO-5).

  12. Study on Non- Isothermal Decomposition Kinetics of Ephedrini Hydrochloridum

    Institute of Scientific and Technical Information of China (English)

    Tang Wan-jun; Chen Dong-hua; Sheng Yu-fang

    2003-01-01

    The thermal decomposition processes of ephed-rini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar meth-od, Coats-Redfern method, and Ozawa method, is put for-ward for determining kinetic model under non-isothermal con-ditions. By applying the combined method, it is determined that the thermal decomposition of ephedrini hydrochloridum is subjected to cylindrical symmetric diffusion. And the reaction function is f(α) = 2(1 - α)1/2, apparent activation energy(115. 26±3.55) kJ @ mol-1 , pre-exponential factor 4. 62 ×108 s-1. Results show that the combined method is feasible and simple.

  13. Novel investigation of enzymatic biodiesel reaction by isothermal calorimetry

    DEFF Research Database (Denmark)

    Søtoft, Lene Fjerbaek; Westh, Peter; Christensen, Knud V.;

    2010-01-01

    Isothermal calorimetry (ITC) was used to investigate solvent-free enzymatic biodiesel production. The transesterification of rapeseed oil with methanol and ethanol was catalyzed by immobilized lipase Novozym 435 at 40 °C. The aim of the study was to determine reaction enthalpy for the enzymatic...... transesterification and to elucidate the mass transfer and energetic processes taking place. Based on the measured enthalpy and composition change in the system, the heat of reaction at 40 °C for the two systems was determined as −9.8 ± 0.9 kJ/mole biodiesel formed from rapeseed oil and methanol, and −9.3 ± 0.7 k...

  14. Adsorption isotherm of uranyl ions by fish scales of corvina

    International Nuclear Information System (INIS)

    Fish scale is by-product of fishery. The scales are mainly formed by hydroxyapatite and collagen forming a kind of natural composite with a large specific surface area that intensifies the adsorption process. In this paper the potential of adsorption of scales of Corvina fish for uranyl ions from nitric solutions was studied. The scales were washed several times with faucet water, sun-dried, triturated and sieved. Equilibrium and kinetic studies in adsorption of uranyl ions in batch systems were carried out at room temperature. Equilibrium time was reached at 5 min for 0.1 g L-1 uranyl solution with removal efficiency over 82%, and at 1 min of contact was observed about 60% of removal. The equilibrium isotherm was obtained and the Langmuir model fitted best. These preliminary results are very promising, showing great perspectives of application of the fish scales as biosorbent for uranyl ions in radioactive wastewater treatment processes with a sustainable technology. (author)

  15. Applications of isothermal titration calorimetry in protein science

    Institute of Scientific and Technical Information of China (English)

    Yi Liang

    2008-01-01

    During the past decade,isothermal titration calorimetry (ITC)has developed from a specialist method for understanding molecular interactions and other biological processes within cells to a more robust,widely used method.Nowadays,ITC is used to investigate all types of protein interactions,including protein-protein interactions,protein-DNA/RNA interactions,protein-small molecule interactions and enzyme kinetics;it provides a direct route to the complete thermodynamic characterization of protein interactions.This review concentrates on the new applications of ITC in protein folding and misfolding,its traditional application in protein interactions,and an overview of what can be achieved in the field of protein science using this method and what developments are likely to occur in the near future.Also,this review discusses some new developments of ITC method in protein science,such as the reverse titration of ITC and the displacement method of ITC.

  16. Adsorption isotherm of uranyl ions by fish scales of corvina

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Caroline Hastenreiter; Santos, Bruno Zolotareff dos; Yamamura, Amanda Pongeluppe Gualberto; Yamaura, Mitiko, E-mail: hc.caroline@gmail.co, E-mail: bzsantos@gmail.co, E-mail: amandaifusp@yahoo.com.b, E-mail: myamaura@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    Fish scale is by-product of fishery. The scales are mainly formed by hydroxyapatite and collagen forming a kind of natural composite with a large specific surface area that intensifies the adsorption process. In this paper the potential of adsorption of scales of Corvina fish for uranyl ions from nitric solutions was studied. The scales were washed several times with faucet water, sun-dried, triturated and sieved. Equilibrium and kinetic studies in adsorption of uranyl ions in batch systems were carried out at room temperature. Equilibrium time was reached at 5 min for 0.1 g L{sup -1} uranyl solution with removal efficiency over 82%, and at 1 min of contact was observed about 60% of removal. The equilibrium isotherm was obtained and the Langmuir model fitted best. These preliminary results are very promising, showing great perspectives of application of the fish scales as biosorbent for uranyl ions in radioactive wastewater treatment processes with a sustainable technology. (author)

  17. Phosphorus isothermal adsorption characteristics of mulch of bioretention

    Directory of Open Access Journals (Sweden)

    Mei Ying

    2012-01-01

    Full Text Available This study aims to identify mulch of bioretention which has high phosphorus sorption capacity. The phosphorus adsorption characteristics of five types of mulch of bioretention are studied by three isothermal adsorption experiments. Results show that the Langmuir eqution is suitable for describing absorption characteristics of five types of mulch. The positive values of Gibbs free energy for phosphorus indicate that the phosphorus biosorption by five mulches is a non-spontaneous process, and the values of mean sorption free energy of mulch are less than 8 kJ/mol, which proves that the adsorption process can be dominated by physical forces. The vermiculite is the better mulch of bioretention based on high phosphorus removal capacity.

  18. Temperature stability limits for an isothermal demagnetization refrigerator

    Science.gov (United States)

    Kittel, P.

    1984-01-01

    It is pointed out that magnetic refrigeration can provide additional cooling for infrared detectors on space missions, taking into account the Shuttle Infrared Telescope Facility (SIRTF) and the Large Deployable Reflector (LDR). From a temperature of 2 K provided by the primary cryogens, magnetic refrigerators could cool bolometers or pumped photoconductors to 0.1 K or below. Such a reduction in operating temperature would increase the sensitivity for bolometers, while the response at longer wavelengths for pumped photoconductors would be improved. Two types of magnetic refrigeration cycles have been proposed. One type uses a complete demagnetization. The present investigation is concerned with the second type, which uses a feedback-controlled isothermal demagnetization, taking into account the temperature stability limits. Attention is given to control system resolution, thermometer noise, reaction time, and thermal time constants.

  19. Moisture ingress into electronics enclosures under isothermal conditions

    Science.gov (United States)

    Staliulionis, Ž.; Jabbari, M.; Hattel, J. H.

    2016-06-01

    The number of electronics used in outdoor environment is constantly growing. The humidity causes about 19 % of all electronics failures and, especially, moisture increases these problems due to the ongoing process of miniaturization and lower power consumption of electronic components. Moisture loads are still not understood well by design engineers, therefore this field has become one of the bottlenecks in the electronics system design. The objective of this paper is to model moisture ingress into an electronics enclosure under isothermal conditions. The moisture diffusion model is based on a 1D quasi-steady state (QSS) approximation for Fick's second law. This QSS approach is also described with an electrical analogy which gives a fast tool in modelling of the moisture response. The same QSS method is applied to ambient water vapour variations. The obtained results are compared to an analytical solution and very good agreement is found.

  20. Liouvillian integrability of gravitating static isothermal fluid spheres

    Science.gov (United States)

    Iacono, Roberto; Llibre, Jaume

    2014-10-01

    We examine the integrability properties of the Einstein field equations for static, spherically symmetric fluid spheres, complemented with an isothermal equation of state, ρ = np. In this case, Einstein's equations can be reduced to a nonlinear, autonomous second order ordinary differential equation (ODE) for m/R (m is the mass inside the radius R) that has been solved analytically only for n = -1 and n = -3, yielding the cosmological solutions by De Sitter and Einstein, respectively, and for n = -5, case for which the solution can be derived from the De Sitter's one using a symmetry of Einstein's equations. The solutions for these three cases are of Liouvillian type, since they can be expressed in terms of elementary functions. Here, we address the question of whether Liouvillian solutions can be obtained for other values of n. To do so, we transform the second order equation into an equivalent autonomous Lotka-Volterra quadratic polynomial differential system in {R}^2, and characterize the Liouvillian integrability of this system using Darboux theory. We find that the Lotka-Volterra system possesses Liouvillian first integrals for n = -1, -3, -5, which descend from the existence of invariant algebraic curves of degree one, and for n = -6, a new solvable case, associated to an invariant algebraic curve of higher degree (second). For any other value of n, eventual first integrals of the Lotka-Volterra system, and consequently of the second order ODE for the mass function must be non-Liouvillian. This makes the existence of other solutions of the isothermal fluid sphere problem with a Liouvillian metric quite unlikely.