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Добірка наукової літератури з теми "Traceurs radioactifs – Technique"

Автор: Grafiati

Опубліковано: 10 червня 2023

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Статті в журналах з теми "Traceurs radioactifs – Technique":

Taney, Norman E. "LABORATORY APPLICATIONS OF RADIOISOTOPIC TRACERS TO FOLLOW BEACH SEDIMENTS." Coastal Engineering Proceedings 1, no. 8 (January 29, 2011): 17. http://dx.doi.org/10.9753/icce.v8.17.

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For many years coastal scientists and engineers have attempted to label sedimentary particles in order that their movement paths might be determined. Several attempts have been made at the Beach Erosion Board, none of which met with any measure of success. Furthermore, inherent in this system is an extensive sampling program and arduous identification of the labeled particles. Recently, however, the labeling of natural sediments or simulated sediments with radioisotopes as tracers has proved successful and a long sought goal has been achieved. The utilization of radioactive material as sediment tracers has increased during the approximately 10 years since its inception. Since the initial test in the Thames River^1' in England, the utilization of this technique has spread until it is practically worldwide!2""8^ In the main, the objectives of these tests have been qualitative, the determination of movement path and of sedimentation areas of the tracer material, and thus of the sediments, which are being followed. Labeling techniques have varied widely and involve plating or precipitating a thin film of radioactive material on the natural sediments, the utilization of glass containing a radioactive tracer to simulate the natural sediments, the incorporation of radioactive material within the natural sediments or within simulated sediments, and ion exchange between the natural sediments and tracer material. The means of detection have also varied broadly: Geiger-Mueller systems with one or several GM tubes in gangs, scintillation systems making use of pulse-height spectrometry, and autoradiographic techniques have all been used. The monitoring has varied also as sediment and tracer materials have been monitored in situ or samples have been taken and the monitoring accomplished in the laboratory. The staff of the Beach Erosion Board has been interested in this new application of radioisotopes since 1955. A literature survey was initiated at that time and is continuing at present. A feasibility study was completed in 1958 which indicated that radioisotopic tracers presented a new technique with which to study sediment transport. The report strongly recommended that studies be planned and executed utilizing this technique. In the Annual Bulletin of the Beach Erosion Board, 1960,^9'several test objectives and procedures were outlined.

Siddle, H. J., D. B. Jones, and C. D. Warren. "The Use of Tracer Techniques to Assess Groundwater Flows in Site Investigations." Geological Society, London, Engineering Geology Special Publications 2, no. 1 (1986): 375–84. http://dx.doi.org/10.1144/gsl.1986.002.01.63.

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AbstractProcedures of site investigation included in BS 5930:1981 concentrate on obtaining information on ground conditions near proposed structures. Groundwater flow paths, however, are often influenced by hydrogeological conditions well beyond the area and tracer tests have been found a useful addition to investigations.Different types of groundwater tracers are described and their uses in establishing groundwater flow paths and other hydrogeological characteristics of some regimes are outlined. Precautions are always necessary when using tracers, however, and these are especially stringent with radioactive tracers. The paper shows how groundwater tracers were employed in investigations of landslips, waste disposal studies and other investigations with which the authors have been involved.The paper concludes that the specification of standard procedures for tracer tests is probably not appropriate but reference to the techniques available would be useful in promoting their application.

Minchin, Peter E. H., and Michael R. Thorpe. "Using the short-lived isotope 11C in mechanistic studies of photosynthate transport." Functional Plant Biology 30, no. 8 (2003): 831. http://dx.doi.org/10.1071/fp03008.

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Tracer techniques have been central in studies of transport in plants. In the case of carbon, the only readily available radioactive tracer has been 14C, although 11C was used for a short time before 14C could be made. Tracers have usually had to be measured by destructive harvesting of the plant, giving a practical limit to the data resolution in both time and space. A major advantage of the short-lived, positron-emitting tracers, of which 11C is one example, is that in vivo measurement is possible, giving detailed time series of tracer data in many locations and opening up powerful new techniques of data analysis. Medical applications of these isotopes have utilised both dynamic imaging and time courses of uptake or washout. Unfortunately, few plant biology laboratories have realised the potential of these techniques, possibly because of the large physics infrastructure needed. In this paper we review the concepts behind the use of these short-lived tracers in plant physiology, and illustrate with several cases where 11C was an essential tool.

Argoud, G. M., D. S. Schade, and R. P. Eaton. "Underestimation of hepatic glucose production by radioactive and stable tracers." American Journal of Physiology-Endocrinology and Metabolism 252, no. 5 (May 1, 1987): E606—E615. http://dx.doi.org/10.1152/ajpendo.1987.252.5.e606.

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Although negative hepatic glucose production rates are physiologically impossible, they have been observed when hepatic glucose production is measured with the tracer-dilution technique during the hyperinsulinemic, euglycemic glucose clamp. Because hepatic glucose production is determined from the difference between tracer-derived glucose disposal and the known exogenous glucose infusion rate, the negative values for hepatic glucose production must result from an underestimation of glucose disposal by the tracer technique. In the current investigation, tracer-derived glucose disposal was measured in 25 subjects undergoing hyperinsulinemic, euglycemic clamps. Glucose disposal was measured with both radioactive and stable isotopes that utilize different methodologies, to determine whether discriminant metabolism of the isotopes versus methodological error leads to underestimation of tracer-derived glucose disposal. Both the radioactive and stable methodologies underestimated the exogenous glucose infusion rate during the hyperinsulinemic euglycemic clamp by 27 and 17%, respectively. Mean hepatic glucose production was -2.1 +/- 0.2 and -1.3 +/- 0.2 mg X kg-1 X min-1 as determined by the radioactive and stable isotope methodologies, respectively. Methodological error was an unlikely cause of this underestimation because it occurred with two different methodologies. The most likely explanation for underestimated rates of glucose disposal determined by the two types of isotope methodologies is discrepant metabolism of glucose tracers in comparison with unlabeled glucose.

Cobelli, C., G. Toffolo, D. M. Bier, and R. Nosadini. "Models to interpret kinetic data in stable isotope tracer studies." American Journal of Physiology-Endocrinology and Metabolism 253, no. 5 (November 1, 1987): E551—E564. http://dx.doi.org/10.1152/ajpendo.1987.253.5.e551.

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In contrast to "weightless" radioactive tracers, stable isotope tracers have nonnegligible mass and are naturally present in the system, and the measured variable is a ratio of two isotopic species. These features do not allow stable isotopic tracer data analysis using straightforward analogy with radioactive tracer approaches, even though this practice is common. In this study, we present kinetic variables, models, and measurements for the analysis and interpretation of stable isotope tracer data. Assumptions and mathematical techniques for modeling the data when perturbation is both nonnegligible and negligible are discussed. Emphasis is placed on the rich information content of the dynamic portion of a stable isotope tracer curve and on the role of compartmental and noncompartmental modeling approaches for its interpretation. A presumed and commonly used analogy between the radioactive specific activity and stable isotopic enrichment is shown to be incorrect. We show that the proper analogue of specific activity is the tracer-to-tracee molar ratio. This variable is not a directly measurable one, but a formula is derived that allows its computation from the data. A method for reconstructing the time course in blood of the concentration component due to endogenous synthesis is presented. This allows measurement of the extent of the perturbation in the case where a nonweightless tracer is used. Special attention is given to data analysis originating from a multiple tracer experiment, a configuration necessary for studying more complex systems, e.g., the kinetics of interacting substrates.

Hill, A. D., Kathryn E. Boehm, and T. J. Akers. "Tracer-Placement Techniques for Improved Radioactive-Tracer Logging." Journal of Petroleum Technology 40, no. 11 (November 1, 1988): 1484–92. http://dx.doi.org/10.2118/17317-pa.

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Salbu, B. "Radioactive tracer techniques in speciation studies." Environmental Technology Letters 8, no. 1-12 (January 1987): 381–92. http://dx.doi.org/10.1080/09593338709384497.

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Salman, Muhammad, Christina Macano, Rishabha D. Sharma, and Alfonso Antequerra. "Magnetic nanoparticle technique versus radioisotope technique in detection of sentinel lymph node in early breast cancer: a systematic review and meta-analysis." International Surgery Journal 8, no. 6 (May 28, 2021): 1870. http://dx.doi.org/10.18203/2349-2902.isj20212284.

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Sentinel lymph node biopsy is the standard technique to stage the axilla in early breast cancer. The gold standard is the dual technique of radioisotope and blue dye injection. The drawbacks of dual technique include handling and disposal of radioactive material. Equally reliable, user and patient friendly, magnetic tracer super paramagnetic iron oxide, was compared with the radioisotope tracer in detection of Sentinel lymph node in a clinically node negative axilla in early breast cancer in this meta-analysis, with emphasis on the utility and safety of both techniques. PubMed, Medline were searched from April 2015 to October 2019. 1395 patients’ data was included from seven homogenous studies in this meta-analysis. A statistical analysis was performed using STATA 16.1 version for sentinel lymph node detection rate using standard technique, magnetic tracer technique and both techniques. Ratio of successes and failures of the outcomes was measured and analysed. A paired two sample ‘Z’ test was performed to compare between the standard technique and magnetic tracer techniques. The standardised mean difference of ratio of success rate between two techniques was; 1.013334 with a p value of 0.3136.The standardised mean difference of ratio of failure rate between two techniques was 1.016667, with a p value of 0.3132. Success and failure rate showed statistically no significant difference between the two techniques. This two-way analysis with paired two sample ‘Z’ test confirms that neither standard technique nor magnetic tracer techniques are superior or inferior to each other.

Coggan, Andrew R. "Use of stable isotopes to study carbohydrate and fat metabolism at the whole-body level." Proceedings of the Nutrition Society 58, no. 4 (November 1999): 953–61. http://dx.doi.org/10.1017/s0029665199001263.

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The present review discusses the advantages and limitations of using stable-isotope tracers to assess carbohydrate and fat metabolism at the whole-body level. One advantage of stable-(v. radioactive-) isotope tracers is the relative ease with which the location of a label within a molecule can be determined using selected-ion-monitoring GC-mass spectrometry (SIM-GC- MS). This technique minimizes potential problems due to label recycling, allows the use of multiple-labelled compounds simultaneously (e.g. to quantify glucose cycling), and perhaps most importantly, has led to the development of unique stable-isotope methods for, for example, quantifying gluconeogenesis. However, the limited sensitivity of SIM-GC-MS sometimes requires that relatively large amounts of a stable-isotope tracer be used, thus increasing cost and potentially altering metabolism. At least theoretically, stable- (or radioactive-) isotope tracers can also be used in conjunction with indirect calorimetry to estimate utilization of muscle glycogen or triacylglycerol stores, thus potentially circumventing the need to obtain muscle biopsies. These calculations, however, require certain critical assumptions, which if incorrect could lead to major errors in the values obtained. Despite such limitations, stable-isotope tracers provide a powerful and sometimes unique tool for investigating carbohydrate and fat metabolism at the whole-body level. With continuing advances in availability, instrumentation and methods, it is likely that stable-isotope tracers will become increasingly important in the immediate future.

Handoo, A. K., and P. K. Ray. "Sputtering of cobalt and chromium by argon and xenon ions near the threshold energy region." Canadian Journal of Physics 71, no. 3-4 (March 1, 1993): 155–58. http://dx.doi.org/10.1139/p93-024.

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Sputtering yields of cobalt and chromium by argon and xenon ions with energies below 50 eV are reported. The targets were electroplated on copper substrates. Measurable sputtering yields were obtained from cobalt with ion energies as low as 10 eV. The ion beams were produced by an ion gun. A radioactive tracer technique was used for the quantitative measurement of the sputtering yield.57Co and 51Cr were used as tracers. The yield–energy curves are observed to be concave, which brings into question the practice of finding threshold energies by linear extrapolation.

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Дисертації з теми "Traceurs radioactifs – Technique":

Ménard, Laurent. "Étude, développement et évaluation clinique d'un imageur gamma per-operatoire." Versailles-St Quentin en Yvelines, 1999. http://www.theses.fr/1999VERS0002.

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L'efficacité du traitement chirurgical du cancer dépend de la localisation précise et de l'ablation complète des lésions tumorales. Dans ce contexte, l'introduction en bloc opératoire de systèmes de détection nucléaire miniaturisés associés à des radio pharmaceutiques pour le marquage des tumeurs permet, en guidant le geste opératoire du chirurgien, de s'assurer en temps réel de la qualité de l'exérèse des tissus cancéreux. L'imageur gamma poci (per-opérative compact imager), qui fait l'objet de cette thèse, a été conçu pour développer et renforcer la technique d'assistance chirurgicale par radio-guidage en apportant un nouvel outil de discrimination entre tissus sains et tissus pathologiques. La phase initiale de recherche des techniques de détection les mieux adaptées a une localisation haute-résolution au contact de la plaie opératoire a abouti au choix d'un imageur modulable élabore autour d'un tube intensificateur d'image lu par une photodiode à localisation bidimensionnelle. La géométrie de deux têtes de détection gamma associant un collimateur à trous parallèles et un scintillateur a ensuite été définie à l'aide de simulations numériques. A partir de ces solutions instrumentales, un premier prototype de poci, possédant un champ de vision de 24 mm de diamètre, a été développé sa caracterisation a mis en evidence une resolution spatiale millimetrique et une efficacité de détection proche de celle des gamma-cameras cliniques, conformement aux previsions numeriques. En collaboration avec l'hôpital Gustave Roussy, l'évaluation clinique de cet imageur per-operatoire a alors été menée sur la localisation transcutanée du ganglion sentinelle pour des patients atteints de mélanomes malins ou de cancers du sein. Les résultats prometteurs obtenus lors de cette étude préliminaire permettent d'envisager, des a présent, de manière favorable, l'utilisation de poci en bloc opératoire et d'étendre son utilisation a d'autres pathologies cancéreuses.

Ponchon, Jean. "Réalisation d'un système d'acquisition pour un appareil destiné à l'étude du métabolisme cérébral au moyen de traceurs radioactifs." Grenoble 1, 1988. http://www.theses.fr/1988GRE10035.

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Thomas, Vincent. "Développement d’un système de mesure ultra-compact à coïncidences électron/photon pour la détection et la caractérisation de radionucléides du xénon." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS454/document.

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Dans le cadre du Traité d'Interdiction Complète des Essais Nucléaires (TICE), le Système de Surveillance International (SSI) a été développé. Ce réseau consiste en plusieurs centaines de stations de mesures dont le rôle est de détecter la signature d'un essai nucléaire clandestin. Quatre types de mesures sont effectués: sismique, hydro-acoustique, infrason et radionucléide. Dans le cas particulier d'un essai nucléaire souterrain, seule la mesure des radionucléides est adéquate pour mettre en évidence le caractère nucléaire de l'explosion. Quatre radionucléides du xénon sont produits en masse lors d'un essai nucléaire: le 131m-Xe, le 133m-Xe, le 133-Xe, et le 135-Xe. Une faible proportion de ces gaz parvient à diffuser à travers les fissures de la cavité et se retrouver dans l'atmosphère. A cause de la dilution atmosphérique, les concentrations de ces quatre radionucléides sont extrêmement faibles et par conséquent difficiles à détecter. De plus, le bruit de fond atmosphérique ne cesse d'augmenter car ces gaz radioactifs sont également produits et relâchés par les usines de production de radio-isotopes médicaux et les centrales nucléaires. Afin de renforcer le réseau de surveillance, le CEA-DAM a proposé de développer un système de détection des radionucléides du xénon ultra-compact et mobile, afin de pouvoir effectuer des mesures de vérification directement sur site suspect, et ainsi contourner la contrainte de dilution atmosphérique. Ces travaux présentent le développement et l'optimisation de ce système. Le système a d'abord été modélisé sur ordinateur et ses performances en terme d'efficacité de détection ont été simulées par méthode de Monte-Carlo avec le logiciel Geant4. Les mesures se font en utilisant la technique de mesure en coïncidences électron/photon. En parallèle, une chaîne d'acquisition ultra-compacte a été développée, ainsi qu'un réseau de communication permettant de synchroniser en temps les différents spectromètres numériques utilisés pour le traitement du signal (protocole IEEE 1588 PTP). Les concentrations minimales détectables de ce système sont inférieures à 5 mBq/m³ pour une acquisition de 12 h, et ce pour les quatre radionucléides du xénon d'intérêt
As part of the Comprehensive nuclear Test Ban Treaty (CTBT), an International Monitoring System (IMS) has been developed. This network consists of several hundred measuring stations whose role is to detect the signatures of a clandestine nuclear test. Four types of measurements are carried out: seismic, hydroacoustic, infrasound and radionuclide. In the particular case of an underground nuclear test, only the radionuclide measurement is adequate to detect the explosion and quantify its yield. Four xenon radionuclides with long half-lives are produced during a nuclear test: the 131m-Xe, the 133m-Xe, the 133-Xe and the 135-Xe. A small proportion of these gases may diffuse through the cracks in the cavity and end up in the atmosphere. Due to atmospheric dilution, the concentrations of these four radionuclides are extremely low and therefore difficult to detect. In addition, atmospheric background continues to increase as these radioactive gases are also produced by medical radioisotope facilities and nuclear power plants. In order to strengthen the IMS, the CEA-DAM has proposed to develop an ultra-compact and mobile system for detecting xenon radionuclides, in order to be able to carry out verification measurements directly on site, and thus to avoid the problem of atmospheric dilution. This work presents the development and optimization of this system. The system was first modelled on a computer and its performances in terms of detection efficiency were simulated by the Monte-Carlo method using Geant4 software. Measurements are made in electron-photon coincidence mode. In parallel, an ultra-compact acquisition chain has been developed, as well as a communication network to synchronize in time the various digital spectrometers used for signal processing (IEEE 1588 PTP protocol). The minimum detectable concentrations of this system are less than 5 mBq/m³ for a 12 h acquisition, for the four xenon radionuclides of interest

Riou, Laurent. "Mecanismes de fixation cellulaire de tcn-noet, un nouveau traceur radioactif de la perfusion myocardique." Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10111.

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Les maladies cardiovasculaires representent la premiere cause de mortalite en france. L'ischemie myocardique est principalement responsable de ces accidents. Le diagnostic de l'ischemie myocardique est actuellement effectue grace a la realisation de scintigraphies myocardiques apres injection d'un traceur radioactif du debit sanguin coronaire, le thallium 201. Cependant, le thallium 201 presente des inconvenients (dosimetrie elevee, energie d'emission mal adaptee, cout de production eleve). Le technetium-99m est un isotope mieux adapte (dosimetrie faible, energie d'emission bien adaptee, cout de production faible). Plusieurs complexes techneties ont ete proposes en remplacement du thallium 201, mais aucun ne presente le meme comportement. Le thallium 201 reste donc le traceur de debit le plus utilise. Tcn-noet est un nouveau complexe technetie presentant le meme comportement que le thallium 201 chez le chien et chez l'homme. Ce traceur est actuellement en essais cliniques de phase iii. L'objectif de ce travail est la determination des mecanismes de fixation cellulaire de tcn-noet. Les etudes realisees in vitro sur cardiomyocytes de rats nouveau-nes indiquent que la fixation cellulaire du traeur est independante de l'etat metabolique des cellules. Cette fixation est inhibee et augmentee par des drogues inhibant et activant, respectivement, les canaux calciques voltage-dependants membranaires. Compte-tenu de l'utilisation frequente des antagonistes calciques en pratique clinique, l'effet du verapamil, du diltiazem et de la nifedipine sur la fixation cardiaque de tcn-noet a ete evalue sur le modele du cur isole et perfuse de rat. Ces drogues sont sans effet sur l'activite cardiaque en tcn-noet. De meme, le verapamil n'affecte pas la fixation myocardique de tcn-noet in vivo chez le chien. Ceci peut s'expliquer par une fixation du traceur ex-vivo et in vivo sur l'endothelium vasculaire, qui ne presente pas de canaux calciques voltage-dependants. En conclusion, tcn-noet est le premier complexe technetie presentant le meme comportement que le thallium 201. In vitro sur cardiomyocytes, ses mecanismes de fixation cellulaire impliquent les canaux calciques voltage-dependants. L'effet d'inhibiteurs de ces canaux n'est pas mis en evidence ex vivo et in vivo, ce qui suggere qu'un traitement par inhibiteurs calciques n'affectera pas la fixation myocardique de tcn-noet en pratique clinique.

Duncan, Henry J. "An isotope washout technique to study skin perfusion pressure and vascular resistance in diabetes, hypertension and peripheral vascular disease /." Cover title, title page, table of contents and summary only, 1986. http://web4.library.adelaide.edu.au/theses/09MD/09mdd911.pdf.

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Thambipillai, Vasumathy. "A study of the diffusion of mercury into cadmium telluride using mainly radioactive tracer techniques." Thesis, Coventry University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278545.

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Hatton, Pierre-Joseph. "Séquestration du carbone et de l’azote des feuilles de hêtre dans les associations organo-minérales du sol : Approches macroscopiques, nanométriques & moléculaires." Electronic Thesis or Diss., Paris, AgroParisTech, 2012. http://www.theses.fr/2012AGPT0050.

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Les associations organo-minérales jouent un rôle prépondérant dans la séquestration à long terme des matières organiques des sols forestiers, mais les contributions des différents types d’association organo-minérale à la stabilisation, ainsi que les processus microbiens qui en sont responsables, restent mal connus. Pour y remédier, des techniques de traçage isotopique ont été combinées à la séparation densitométrique séquentielle des associations organo-minérales. Ces dernières ont été investiguées in et ex situ, à différentes échelles spatiales (macroscopique, submicrométrique et moléculaire) et temporelles (de 8 heures à 12 ans).Quatre types d’association organo-minérale ont été distingués : les débris végétaux associés à quelques rares minéraux, les agrégats végétaux, les agrégats microbiens et les grains minéraux. Le traçage isotopique du carbone et de l’azote dérivés des litières de feuilles a mis en évidence, à l’échelle de la décennie, des transferts entre les différentes associations organo-minérales. Tous deux entrent dans le sol sous forme de fragments végétaux, puis migrent progressivement vers les agrégats végétaux et microbiens. Les agrégats apparaissent pertinents pour la stabilisation du carbone et de l’azote à l’échelle décennale. Une petite fraction du carbone et de l’azote apparaît rapidement stabilisée dans les grains minéraux denses. Nos observations du devenir du 15N indiquent que l’activité des microorganismes du sol est responsable de ces transferts. Les fragments de feuilles colonisés par les microorganismes sont progressivement incorporés dans les agrégats végétaux. A mesure que la décomposition se poursuit, les agrégats végétaux se disloquent pour former des agrégats plus stables, plus pauvres en matières organiques, plus enrichis en produits microbiens et plus compacts : les agrégats microbiens. La stabilisation microbienne a été étudiée aux échelles macroscopique, submicrométrique et moléculaire, principalement par NanoSIMS et LC-IRMS. Elle opère (i) directement par immobilisation dans les cellules microbiennes et (ii) indirectement via une abondante production de métabolites extracellulaires. La calibration des C/N obtenus par NanoSIMS a permis de déterminer qu’ils sont stabilisés dans les associations organo-minérales sans contrôle apparent de la chimie des matières organiques. L’incorporation du 13C dans les sucres aminés, biomarqueurs des biomasses bactériennes et fongiques, indique que les microorganismes vivants croissent où la ressource se trouve. Ils s’accumulent dans les agrégats microbiens via les processus de transfert précédemment évoqués. Ce travail souligne l’importance des agrégats pour la séquestration du carbone et de l’azote dérivés des litières à l’échelle de la décennie. Il met également en évidence le rôle des microorganismes dans les transferts et la stabilisation du carbone et de l’azote dérivés des feuilles au sein d’associations organo-minérales
Organo-mineral associations play a key role in the long-term sequestration of organic matter in forest soils. However, knowledge about the contribution of the different types of organo-mineral associations and the microbial processes involved in soil organic matter stabilisation is scant. To solve it, stable isotope techniques have been combined with the sequential density fractionation of organo-mineral associations. Isolated fractions were investigated in field and in lab, at different temporal (from 8 hours to 12 years) and spatial scales (macro-, submicron- and molecular scales).Four types of organo-mineral associations were distinguished: plant debris with little mineral attached, plant aggregates, microbial aggregates and mineral grains. Isotopically labeled beech leaf litters were tracked at a decadal time-scale to reveal transfers in between organo-mineral associations. Both litter-derived carbon and nitrogen entered the soil as plant fragments to progressively pass through plant and microbial aggregates. Aggregates appeared particularly meaningful for the stabilisation of litter-derived carbon and nitrogen at a decadal time-scale. Little of the litter-derived carbon and nitrogen was found quickly stabilized to mineral grains. Microbial activities appeared as a major controlling factor for the evolvement of organo-mineral associations, responsive for the transfers of litter-derived carbon and nitrogen. Indeed, plant debris colonized by microorganisms are progressively trapped into plant aggregates. As decomposition proceeds, plant aggregates disrupt into denser microbial aggregates. These aggregates are loaded with lesser organic matter, but enriched in stable microbial materials.Stabilisation by soil microorganisms has been studied at the macro-, submicronand molecular- scales, using mostly NanoSIMS and LC-IRMS. Microbial stabilization operated (i) directly through immobilization in microbial cells and, (ii) indirectly through large production of extracellular microbial products. By calibrating the NanoSIMS for accurate C/N ratios, extracellular microbial products have been shown to be stabilized onto organo-mineral associations without apparent control of the mineral-attached organic matter chemistry. The incorporation of 13C tracers into amino sugars, biomarkers of bacterial and fungal biomasses, revealed that living microorganisms grow where the resource is, but accumulate in microbial aggregates. Microbial biomasses moved from plant debris to microbial aggregates, likely along with the transfers of decaying litter residues as described above.This work points aggregates as meaningful organo-mineral associations for the sequestration of litter-derived carbon and nitrogen at the decadal time-scale. It also revealed the role of microorganisms in the transfers and stabilization of litterderived carbon and nitrogen within organo-mineral associations

Singh, D. P. "Flow and mixing studies in a co-rotating intermeshing twin screw extruder." Thesis, Brunel University, 1988. http://bura.brunel.ac.uk/handle/2438/5548.

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The basic understanding of mixing in the process of polymer melt extrusion by twin screw extruder is limited by their geometrical complexity and the interactions of the process parameters. Mixing and flow in a 100mm diameter, trapezoidal channeled, intermeshing co-rotating twin-screw extruder have been characterised by determination of residence time distribution (RTD) and of the paths taken by tracers added to the melt. The axial mixing and the effects of varius parameters on it were established by studying RTD using tracer techniques. As the tail of the distribution is of paramount importance, the reproducibility of the RTD curve was extensively studied. Radioactive NnO2 was used as a tracer and detected by gamma ray spectroscopy giving more reproducible results than added barytes estimated gravimetrically after ashing. Shock cooling of the extruder and sectioning of the solidified compound in the screw channels was used to-study the flow mechanism. The maximum throughput achieved, polymer melting mechanism, filled volume and axial mixing Are interrelated, and are dependent on the configuration and position of segmented mixing discs present in the screw profile. In the upstream position these act as melting discs and their efficiency is increased in a closed configuration. Initial melting is achieved over a remarkably short distance along the screw profile. The screw speed affects the axial mixing which is shown to be related to the net relative pressure change at the screw tips. A flow model is proposed such that the overall material flow taking place in an anticlockwise direction along the screw channel comprises two separate flow regimes. The upper regime rotates anti-clockwise and is made up of main and small tetrahedron flow and calender flow. The lower flow regime rotates clockwise and is made up of main and small side leakage flows and a portion of the main tetrahedron flows together with a central flow. The flow studies show conclusively that the melt from a particular site ahead of the intermeshing zone occupies a predestined site after passing through the intermeshing zone.

Grimaldo, Morón José Teófilo. "Contribution à la synthèse de macrocycles tétraphosphorés : ligands polydentates présentant un intérêt biomédical." Grenoble 1, 1987. http://www.theses.fr/1987GRE10161.

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Synthese de ligands macrocycles tetraphores, complexants potentiels de cations paramagnetiques (gd**(3+), fe**(3+)) et de nucleide radioactifs. Etude de la reactivite de ces ligands et des essais de complexation

Duncan, Henry J. (Henry John). "An isotope washout technique to study skin perfusion pressure and vascular resistance in diabetes, hypertension and peripheral vascular disease." 1986. http://web4.library.adelaide.edu.au/theses/09MD/09mdd911.pdf.

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Книги з теми "Traceurs radioactifs – Technique":

International Symposium on Modern Insect Control (1987 Vienna, Austria). Modern insect control: Nuclear techniques and biotechnology ; proceedings of an International Symposium on Modern Insect Control: nuclear techniques and biotechnology. Vienna: International Atomic Energy Agency, 1988.

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International Symposium on Modern Insect Control: Nuclear Techniques and Biotechnology (1987 Vienna, Austria). Modern insect control: Nuclear techniques and biotechnology : proceedings of an International Symposium on Modern Insect Control: Nuclear Techniques and Biotechnology. Vienna: The Agency, 1988.

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International Symposium on Isotope Techniques in Water Resources Development (1991 Vienna, Austria). Isotope techniques in water resources development 1991: Proceedings of an International Symposium on Isotope Techniques in Water Resources Development. Vienna: International Atomic Energy Agency, 1992.

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International Symposium on Harmonization of Health Related Environmental Measurements Using Nuclear and Isotopic Techniques (1996 Hyderabad, India). Harmonization of health related environmental measurements using nuclear and isotopic techniques: Proceedings of an International Symposium on Harmonization of Health Related Environmental Measurements Using Nuclear and Isotopic Techniques. Vienna: International Atomic Energy Agency, 1997.

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Agency, International Atomic Energy, ed. Use of isotope techniques to trace the origin of acidic fluids in geothermal systems. Vienna, Austria: International Atomic Energy Agency, 2005.

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International Symposium on the Use of Isotope Techniques in Water Resources Development (1987 Vienna, Austria). Isotope techniques in water resources development: Proceedings of an International Symposium on the Use of Isotope Techniques in Water Resources Development ... Vienna, 30 March-3 April 1987. Vienna [Austria]: The Agency, 1987.

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International Symposium on Changing Perspectives in Agrochemicals: Isotopic Techniques for the Study of Food and Environmental Implications (1987 Neuherberg, Germany). Pesticides: Food and environmental implications : proceedings of an International Symposium on Changing Perspectives in Agrochemicals: Isotopic Techniques for the Study of Food and Environmental Implications. Vienna: International Atomic Energy Agency, 1988.

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International, Symposium on Isotope Techniques in the Study of Past and Current Environmental Changes in the Hydrosphere and the Atmosphere (1997 Vienna Austria). Isotope techniques in the study of environmental change: Proceedings of an International Symposium on Isotope Techniques in the Study of Past and Current Environmental Changes in the Hydrosphere and the Atmosphere. Vienna: The Agency, 1998.

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International, Symposium on the Use of Nuclear Techniques in Studies of Animal Production and Health in Different Environments (1986 Vienna Austria). Nuclear and related techniques in animal production and health: Proceedings of an International Symposium on the Use of Nuclear Techniques in Studies of Animal Production and Health in Different Environments. Vienna: The Agency, 1986.

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International Symposium on Applications of Isotope Techniques in Studying Past and Current Environmental Changes in the Hydrosphere and the Atmosphere (1993 Vienna, Austria). Isotope techniques in the study of past and current environmental changes in the hydrosphere and the atmosphere: Proceedings of an International Symposium on Applications of Isotope Techniques in Studying Past and Current Environmental Changes in the Hydrosphere and the Atmosphere. Vienna: The Agency, 1993.

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Частини книг з теми "Traceurs radioactifs – Technique":

Jones, T. L. "Radioactive tracer applications." In Radioisotope Techniques for Problem-Solving in Industrial Process Plants, 84–96. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4073-4_7.

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Johnson, P. "Measurement of flow using radioactive tracers." In Radioisotope Techniques for Problem-Solving in Industrial Process Plants, 97–111. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-009-4073-4_8.

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Morris, Donald A. "Use of Chemical and Radioactive Tracers at the National Reactor Testing Station, Idaho." In Isotope Techniques in the Hydrologic Cycle, 130–42. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm011p0130.

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Klutmann, S., K. H. Bohuslavizki, S. Kröger, S. Höft, J. A. Werner, W. Brenner, and E. Henze. "Lymphoscintigraphy in Tumors of the Head and Neck Using a Double Tracer Technique." In Radioactive Isotopes in Clinical Medicine and Research XXIII, 179–84. Basel: Birkhäuser Basel, 1999. http://dx.doi.org/10.1007/978-3-0348-8782-3_27.

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Barry, P. J. "The Use of Radioactive Tracer Gases to Study the Rate of Exchange of Water Vapor between Air and Natural Surfaces." In Isotope Techniques in the Hydrologic Cycle, 69–76. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm011p0069.

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Sun, Jian Gang, and Michael Ming Chen. "Radioactive Tracer Techniques." In Instrumentation for Fluid Particle Flow, 354–401. Elsevier, 1999. http://dx.doi.org/10.1016/b978-081551433-6.50011-6.

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Eberle, Douglas. "Radioactive tracer methods." In Techniques for Corrosion Monitoring. CRC Press, 2008. http://dx.doi.org/10.1201/9781439824184.ch10.

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Eberle, Douglas C. "Radioactive tracer methods." In Techniques for Corrosion Monitoring, 265–76. Elsevier, 2008. http://dx.doi.org/10.1533/9781845694050.2.265.

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Eberle, Douglas C. "Radioactive tracer methods." In Techniques for Corrosion Monitoring, 255–66. Elsevier, 2021. http://dx.doi.org/10.1016/b978-0-08-103003-5.00010-2.

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McDougall, I. Ross, and Andrei Iagaru. "Thyroid imaging: nuclear medicine techniques." In Oxford Textbook of Endocrinology and Diabetes, 345–54. Oxford University Press, 2011. http://dx.doi.org/10.1093/med/9780199235292.003.3054.

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Thyroid imaging with radio-isotopes of iodine provides functional and quantitative information. Images, scans, or scintiscans are the terms used for the pictures that are obtained. In general, a radionuclide or radiopharmaceutical is administered orally or intravenously and images of the distribution of the radioactive tracer are obtained after specific times using a gamma camera. Some clinicians employ a rectilinear scanner rather than a gamma camera to produce the images, but this should not be considered state of the art. Scintiscans do not have the resolution of ultrasonography, CT, or MRI, but they provide reasonable anatomical information as well as functional information. A numerical uptake measurement of how much of the tracer has been trapped can be obtained at the same time as the scintiscan to provide complementary quantitative information. Imaging with radio-iodine is of great value in the diagnosis and management of patients with thyrotoxicosis and differentiated thyroid cancer. It is of less value in thyroid nodules, hypothyroidism, simple goitre, and undifferentiated thyroid cancer. The chapter starts with a discussion of the radioactive tracers and the methods for scanning. Then the appearance of a normal scan followed by findings in patients with thyrotoxicosis, simple goitre, nodular goitre, and congenital defects are described. In these situations the scintiscan evaluates the region of the thyroid. Finally, the role of nuclear medicine imaging in patients with cancer of the thyroid is presented separately since the imaging is different in that it usually evaluates the whole body.

Тези доповідей конференцій з теми "Traceurs radioactifs – Technique":

Taleghani, Arash Dahi, and Ping Puyang. "Efficiency of Multi-Zone Fracturing in Vertical Wells: A Case Study." In ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-11623.

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Extensive multi-zone multistage hydraulic fracturing treatments are now being executed in low permeability oil and gas fields around the world. Due to the limited access to the subsurface, post-treatment assessments are mainly limited to few techniques such as tiltmeter, microseismic and tracer-logs. The first two techniques are mainly used to determine fracture extension; however, fracture height and fracture initiation at all perforation clusters could only be confirmed through radioactive tracer logs or detailed pressure analysis. In this paper, we consider real examples from a field from Central America and investigate potential problems led to the limited generation of fractures in multi-zone treatments. For instance, some of the post-frac radioactive logs show very low concentration of tracers at some perforated zones in comparison with other zones. On the other hand in some cases, tracer logs indicate presence of tracers in deeper or shallower zones. Different reasons could cause fracture growth in non-perforated zones, including but not limited to: perforation design problems, casing/cement integrity problems, lack of containment, instability of fracture growth in one or some of the zones, and finally making a mistake in selecting lithology for fracturing. In this paper, some of these issues have been examined for a few sample wells using treatment pressure data, petrophysical logs and post-frac tracer logs. Some recommendations in designing the length and arrangement of perforations to avoid these problems in future fracturing jobs are provided at the end of this paper.

Alyan, Mohand, Shardul Parihar, Latifa AlHaji, Edmund Leung, Craig Elder, Alaa Othman, Ahmed Altamimi, Manal AlHarbi, Ahmed Al Kiyoumi, and John Wills. "Novel Application of Inflow Tracers in Record Well for Assessing 1-MD Reservoir." In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211403-ms.

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Abstract In order to quantify and monitor inflow along the deepest 5,000 ft of a 45,000 ft extended-reach drilling (ERD) well, a (non-radioactive) permanent inflow tracer system was installed, sampled, and analyzed. The tracer technology was piloted as a supplementary downhole data source to the existing practice of intervention-based production logging due to current limitations of intervention accessibility. This application aided in assessing contribution of the lateral segment within a 1-md reservoir quality rock and determining clean-up efficiency. The deployed lower completion is a 6⅝-in limited entry liner, segmented by packers with design specifically optimized for bullhead stimulation. To meet well objectives, the design of lower completion, along with placement of tracer carrier subs, was geometrically optimized based on expected flow streams. Final deployment included 3 externally vented tracer carrier subs per compartment with optimized spacing, each mounted with a chemically different tracer for both oil and water. A total of 21 distinct signature tracers were deployed per phase within the 7 compartments with compartment length ranging from 681 to 782 ft. In addition, liner is equipped with dissolvable plugged nozzles for efficient mud cake breaker displacement. Upon activation, the well was flowed for 2 weeks at maximum rate for efficient clean-up before shutting it for 1 week for tracer concentration build up. The well was then flowed, and 106 samples were taken in a decreasing sampling frequency. A subset of 17 samples were selected for analysis – the collected samples were oil with no traces of water. Analysis of the tracer concentration with time showed the arrival of all 21 oil tracer signals and peaks, followed by a decreasing trend towards steady state levels. Results indicate that all reservoir zones contribute to oil production and that all zones have responded similarly in terms of the tracer profiles. This suggests a homogenous reservoir pressure drawdown across all zones. Furthermore, this indicates that reservoir zones cleaned-up efficiently and demonstrates effectiveness of an applied mud cake breaker displacement technique. The tracer results indicate minimum formation damage – in line with expectations, as the target area is a homogeneous 1-md rock quality with uniform reservoir pressure. Using the tracer data, a quantitative interpretation was performed, by use of the so-called flush out tracer transport model. The methodology was successful in determining relative flow contribution per traced zone. Results shows a uniform relative inflow contribution ranging from 4 to 6% per zone. The chemical inflow tracers were deployed in a well with world-record length of 6⅝-in lower completion at 29,243 ft, beyond current accessibility limits of rigless intervention. Also, the well is ranked 5th worldwide (as of time of this writing) in terms of longest well at 45,000 ft, thus making it a world-record in terms of the deepest deployment of chemical inflow tracers.

Al-Jahdhami, Ahmed Rashid, Juan Carlos Chavez, and Shaima Abdul Aziz Al-Farsi. "Fiber Optic Deployed Behind Cemented Casing in a Vertical Deep Tight Gas Well Used to Enhance Hydraulic Fracturing, Monitoring and Diagnostics." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207614-ms.

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Abstract The use of fiber optic (FO) to obtain distributed sensing be it Distributed Temperature Sensing (DTS), Distributed Acoustic Sensing (DAS) or Distributed Strain Sensing (DSS) is a well & reservoir surveillance engineer's dream. The ability to obtain real-time live data has proven useful not only for production monitoring but during fracture stimulation as well. A trial the first of its kind in Petroleum Development Oman (PDO) used fiber optic cable cemented in place behind casing to monitor the fracture operations. Several techniques are used to determine fracture behaviour and geometry e.g. data fracs, step down test and after closure analysis. All these use surface pressure readings that can be limited due to uncertainty in friction pressure losses and the natural complexity in the formation leading to very different interpretations. Post frac data analysis and diagnostics also involves importing the actual frac data into the original model used to design the frac in order to calibrate the strains (tectonics), width exponent (frac fluid efficiency) and the relative permeability. Monitoring the frac using DAS and DTS proved critical in understanding a key component in fracture geometry; frac height. The traditional method to determine fracture height is to use radioactive tracers (RA). But these are expensive and the data only available after the job (after drilling the plugs and cleaning the wellbore). In contrast fiber optic can provide real time data throughout the frac stages including the proppant free PAD stage which tracers can't. The comparison of DTS and Radioactive Tracers showed very good agreement suggesting that DTS could replace RA diagnostic. Hydraulic fracture stimulation operations in well-xx was the first one of its kind to be monitored with fiber optic. The integrated analysis of the available logs allowed us to benchmark various information and gain confidence in the conclusions. This helped fine tune the model for future wells for a more optimized zonal targeting and hydraulic fracture design. In this paper we will share the detailed evaluation of the fracture propagation behaviour and how combining the fiber optic data with the surface pressure, pumping rates and tracer logs in conjunction with a fracture simulation platform where a detailed geomechanical and subsurface characterization data is incorporated to get a more accurate description of fracture geometry.

Jaboob, Musallam, Ahmed Al Shueili, Hussien Al Salmi, Salim Al Hajri, German Merletti, Rifat Kayumov, Stevanus dwi Kurniadi, and Ricardo Sebastian Trejo. "Fracture Geometry Calibration Using Multiple Surveillance Techniques." In SPE International Hydraulic Fracturing Technology Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/205280-ms.

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Abstract An accurate Mechanical Earth Model (MEM) is of vital importance in tight gas reservoirs where hydraulic fracturing is the only way to produce hydrocarbons economically. The Barik tight gas reservoir is the main target in Khazzan and Ghazeer Fields at the Sultanate of Oman (Rylance et al., 2011). This reservoir consists of multiple low-permeability sandstone layers interbedded with marine shales. A good understanding of the fracture propagation in such a reservoir has a major effect on completion and fracturing design. The MEM derived from sonic logs and calibrated with core data needs to be further validated by independent measurements of the fracturing geometry. Multiple surveillance techniques have been implemented in the Barik reservoir to validate the MEM and to match observations from hydraulic fracturing operations. These techniques include closure interpretation using a wireline deployed formation testing assembly, the use of mini-frac injection tests with deployed bottomhole pressure gauges, execution of post injection time-lapse temperature logging, the injection of radioactive tracers, associated production logging, subsequent pressure transient analysis and other techniques. A cross-disciplinary team worked with multiple sources of data to calibrate the MEM with the purpose of delivering a high-confidence prediction of the created fracture geometry, which honors all available surveillance data. In turn, this validation approach provided a solid basis for optimization of the completion and fracturing design, in order to optimally exploit this challenging reservoir and maximize the economic returns being delivered. For example, combination of stress testing with radioactive tracers provided confidence in stress barriers in this multilayered reservoir. Pressure transient analysis allowed to calibrate mechanical model to match fracturing half-length that is contributing to production. This paper provides extensive surveillance examples and workflows for data analysis. Surveillance of this degree in the same well is uncommon because of the associated time and cost. However, it provides unique value for understanding the target reservoir. This paper demonstrates the Value Of Information (VOI) that can be associated with such surveillance and provides a concrete and practical example that can be used for the justification of future surveillance programs associated with the hydraulic fracturing operations.

Lopez, Alejandro. "Radiological Issues Associated With the Recent Boom in Oil and Gas Hydraulic Fracturing." In ASME 2013 15th International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icem2013-96119.

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As the worldwide hydraulic fracturing ‘fracking’ market continued to grow to an estimated $37 Billion in 2012, the need to understand and manage radiological issues associated with fracking is becoming imperative. Fracking is a technique that injects pressurized fluid into rock layer to propagate fractures that allows natural gas and other petroleum products to be more easily extracted. Radioactivity is associated with fracking in two ways. Radioactive tracers are frequently a component of the injection fluid used to determine the injection profile and locations of fractures. Second, because there are naturally-occurring radioactive materials (NORM) in the media surrounding and containing oil and gas deposits, the process of fracking can dislodge radioactive materials and transport them to the surface in the wastewater and gases. Treatment of the wastewater to remove heavy metals and other contaminates can concentrate the NORM into technologically-enhanced NORM (TENORM). Regulations to classify, transport, and dispose of the TENORM and other radioactive waste can be complicated and cumbersome and vary widely in the international community and even between states/provinces. In many cases, regulations on NORM and TENORM do not even exist. Public scrutiny and regulator pressure will only continue to increase as the world demands on oil and gas continue to rise and greater quantities of TENORM materials are produced. Industry experts, health physicists, regulators, and public communities must work together to understand and manage radiological issues to ensure reasonable and effective regulations protective of the public, environment, and worker safety and health are implemented.

Mohamed Samer, Werner Berg, Merike Fiedler, Kristina von Bobrutzki, Christian Ammon, Peter Sanftleben, and Reiner Brunsch. "A comparative study among H2O-balance, heat balance, CO2-balance and radioactive tracer gas technique for airflow rates measurement in naturally ventilated dairy barns." In 2012 IX International Livestock Environment Symposium (ILES IX). St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2012. http://dx.doi.org/10.13031/2013.41613.

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Moiseenkov, Alexey, Dmitrii Smirnov, Abdullah Al Hadhrami, Pankaj Agrawal, Amira Harrasi, Monther Manthari, Asaad Busaidi, Khayrutdinov Fanis, Ernest Sayapov, and Omar Isaee. "Successful Unconventional Fracturing Tight and Highly Laminated Silicilyte Reservoir Leading to Economic Field Development." In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/207818-ms.

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Abstract South Oman contains several tight silicilyte reservoirs with significant locked hydrocarbon volumes. Successful hydraulic fracturing is key for unlocking commercial production. Low production rates coupled with fast declines have remained a challenge and a new economically attractive development scheme was required. Through integrated re-evaluation of the geology and reservoir, a modified frac approach was designed to create more connectivity to the reservoir height, using an unconventional frac design and frac fluids plus over-flush. Poor well productivity in tight silicilyte reservoir can be explained by low permeability of 0.001-0.1 mD and laminated texture with almost zero vertical permeability. Fit for purpose modelling was performed to assess the forecasting range for sub-surface uncertainties and frac parameters. One of the key changes for a successful development strategy was to place a higher number of fracs to overcome the extreme lamination. [1] It was observed that the "conventional" fracturing approach inaccurately assumed higher vertical fracture coverage of the reservoir and that the guar fluid used was much more damaging due to low recovery after frac clean-up. Fifteen unconventional fracs were pumped successfully with over-flush pumping technique. To understand if this new unconventional approach was effective in overcoming the extreme lamination required additional understanding of fractures geometry and orientation. To confirm fracture dimensions and flowing heights; a set of radioactive, chemical tracers and logging activities were completed. Flowback results showed that the unconventional frac [3] fluid used, was relatively easy to recover from formation and better cleaning-up of fractures can be achieved. This led to successful well clean-up compared to previous wells in the same field and confirmed better fracs clean up. Initial production results confirmed at least double well initial productivity, which should lead to better stable oil production from the field. Radioactive tracers logging, Sonic logging and Spectrum Noise Logging (SNL) confirmed mechanical and conductive fracture heights. Sonic logging also confirmed frac orientation. Oil and water dissolvable tracers confirmed fractures clean up from water and oil production intervals. Full geological and reservoir understanding, out of box thinking in frac technology allowed the asset team to come up with an unconventional development approach to improve commercial production from tight silicilyte reservoirs. The new frac approach included unconventional frac design and fluids, and execution using over flush and resulted into unlocking significant reserves. A more economic full field development is being planned and replication of the new frac approach is already ongoing in other fields.

Pottinger, M. P., and C. H. Orr. "Free-Release Monitoring Equipment in the UK Nuclear Power Industry." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4564.

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In the nuclear power industry, many techniques are used to confirm that items are suitable for free-release. These techniques usually involve monitoring of the items with at least one type of radiometric instrument, to ensure that no significant quantity of man-made radioactivity is present. These monitoring techniques depend on the stage in the clearance process, the application and the size of the article being monitored. The UK Radioactive Substances Act has a Substances of Low Activity (SoLA) exemption which allows for articles and waste that have a man-made radioactive content less than 0.4 Bq g−1, to be classified as non-radioactive and be discharged from site in similar fashion to conventional wastes. Identifying whether the waste meets the criteria is technically challenging due to the low level of this exemption. Consequently the detection limits of most common portable radiation protection instrumentation is higher than this level. Historically portable alpha and beta contamination instruments are used as part of the clearance process; these are reasonably effective at monitoring the surface of an object for the presence of radioactivity, but far less so for bags of waste where alpha and beta emissions are easily absorbed within the waste. Portable gamma only contamination instruments have proved effective where some contaminants emit gamma radiation. However even these instruments have some difficulty in confirming that an article is “free” from man-made radioactivity where the mass of the article is below a critical mass. In this industry, the radioactive fingerprint will typically include an easily detectable gamma emitting radionuclide such as 60Co, or 137Cs, which may be used as a tracer for other radionuclides which cannot be easily detected with such an instrument. Installed clearance (bag) monitors are very effective where the user has a good knowledge of the radioactive fingerprint, and where there are significant (more than 10%) gamma emitting radionuclides in the fingerprint. They are ineffective where pure alpha and beta emitters dominate the radioactive fingerprint. These monitors are capable of monitoring to 1/10 of the SoLA exemption level for 60Co, with a small variation in response across the volume of the measurement chamber. Inevitably these instruments are also sensitive to NORM, so a good knowledge of NORM activity concentrations is each waste stream is required for adequate compensation. Vehicle monitors are useful for reassurance monitoring, although due to the variable nature of each waste consignment and the high background count rate, their high detection limit means they are not suitable as the sole means of free release monitoring.

Al-Yaarubi, Azzan, Sumaiya Al Bimani, Sataa Al Rahbi, Richard Leech, Dmitrii Smirnov, Alexey Moiseenkov, Ernest Sayapov, and Omar Isaee. "Applying Slim Dipole Sonic Tool to Evaluate Hydraulic Fracture Geometry and Orientation Using the Differential Sonic Method." In SPE International Hydraulic Fracturing Technology Conference & Exhibition. SPE, 2022. http://dx.doi.org/10.2118/205329-ms.

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Abstract Successful hydraulic fracturing is critical for hydrocarbon recovery from tight reservoirs. Fracture geometry is one essential quality indicator of the created fracture. The geometry provides information about the size of the created fracture and containment and verifies the pre-job modeling. Different techniques are applied to determine fracture geometry, and each has its own advantages and limitations. Due to its simplicity, the radioactive tracer log is commonly used to determine fracture placement and fracture height. Its main drawbacks include shallow depth of investigation, time dependency, and the requirement for multiple interventions for multistage fracturing operations. The crosswell microseismic technique probes a larger volume and it is potentially capable of providing fracture height, length, and orientation. Operational complexity and long processing turnaround time are the main challenges of this technique. Time-lapse shear slowness anisotropy analysis is an effective method to determine hydraulic facture height and orientation. In this technique, the shear slowness anisotropy is recorded before and after the fracture is created. The observed shear anisotropy difference indicates the intervals where the fractures were created, allowing these intervals lengths to be measured. Combining this analysis with gyroscopic data allows determining the fracture orientations. Compared to a tracer log, the differential casedhole sonic anisotropy (DCHSA) has a deeper depth of investigation, and it is time independent. Thus, the repeated log can be acquired at the end of the multistage fracturing operations. Compared to the microseismic technique, this new technique provides more precise fracture height and orientation. The new generation slim dipole sonic technology of 2.125-in. diameter extends the applicability of the DCHSA technique to smaller casing sizes. The shear differential method was applied to a vertical well that targeted the Athel formation in the south of the Sultanate of Oman. This formation is made of silicilyte and is characterized by very low permeability of about 0.01 md on average. Thus, hydraulic fracturing plays a critical role for the economic oil recovery in this reservoir. Aiming to achieve a better zonal contribution, the stimulation design was changed from a limited number of large fractures to an extensive multistage fracturing design in the subject well. Sixteen hydraulic fracturing stages were planned. The DCHSA was applied to provide accurate and efficient fracture geometry evaluation. The DCHSA accurately identified fracture intervals and their corresponding heights and orientations. This enabled effectively determining the created fracture quality and helped explain the responses of the production logs that were recorded during the well test. This study provided a foundation for the placement and completion design of the future wells in the subject reservoir. It particularly revealed adequate fracturing intervals and the optimum number of stages required to achieve optimum reservoir coverage and avoid vertical overlapping.

Adamson, David William, and Jonathan Francis. "The Emergence of Sustainable Practice Within Decommissioning." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16059.

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Despite the advance of sustainable practice and energy efficient techniques outside of the nuclear industry, at the start of the 21st Century there was a lack of published guidance aimed at their adoption at specifically nuclear facilities. Even with the establishment of the Nuclear Decommissioning Authority, there is very little guidance published on how to adopt sustainable practices during decommissioning. There have been instances where energy efficiency had affected design and operations decisions. Projects aimed at responsible housekeeping, switching off lights, and changes to the nuclear ventilation design philosophy illustrate a desire for action, but these activities were championed by interested and motivated employees. Sustainable practice had not at that time received a strategic lead that resulted in a management structure to enable a coordinated and concerted effort in sustainable practice. This paper traces the progress during the 20th and early 21st Centuries, whereby sustainable practice is now established within a much firmer foundation of case study, guidance and organisational structure; to embed sustainable practice within the United Kingdom’s current decommissioning programme. It looks at the development of relevant literature and, through interviews with key managers and external stakeholders, demonstrates (i) the degree to which two essential guidance documents (the NiCOP and CIRIA SD:SPUR) are permeating the industry, (ii) how the current work of the Characterisation and Clearance Group has evolved to influence the decontamination and dismantling planning procedures and (iii) the transition from identifying ‘free-release’ materials to actually releasing them for re-use in the community.