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Letteratura scientifica selezionata sul tema "Α-emitters"

Autore: Grafiati

Pubblicato: 14 settembre 2024

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Articoli di riviste sul tema "Α-emitters"

Aarab Terrisse, Safae, Chris C. Parker, Karamouza Eleni, A. Oliver Sartor, Nicholas James, Sarah Pirrie, Laurence Collette et al. "A meta-analysis on individual data of bone-targeting radio-isotopes in men with bone metastases from castration-resistant prostate cancer." Journal of Clinical Oncology 36, n. 6_suppl (20 febbraio 2018): 352. http://dx.doi.org/10.1200/jco.2018.36.6_suppl.352.

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352 Background: Among bone-targeted radio-isotopes (RI), Radium-223 (an α-emitter) is the only one with clearly demonstrated overall survival (OS) benefit in men with castration-resistant prostate cancer (CRPC). The aim of this meta-analysis is to estimate the OS impact of RI in men with CRPC. Methods: An individual patient data meta-analysis was carried out from randomized trials with inclusion period 1993-2013. Eligible trials included more than 50 patients, mandated bone metastases from CRPC and randomly evaluated RI. Endpoints were OS (primary), symptomatic skeletal events (SSE) and toxicity. A fixed-effect model was used. The log-rank test stratified by trial was used to estimate individual and overall hazard ratios (HR). Subset analyses were performed by the type of radiation (α vs. β emission) and by trial comparison: RI + Chemotherapy (CT) vs. CT, RI+ External beam radiotherapy (EBRT) vs. EBRT, RI vs. EBRT. Results: From 9 identified trials, data from 6 trials comprising 2081 patients (min: 64, max: 921) were collected with 2 trials representing 80% of data. The data from 3 trials (n = 341) were not available. The overall effect on OS favoured RI with HR = 0.86 [0.77-0.95] but high heterogeneity between trials (p < 0.001, I2= 79.6%). The overall effect of α- emitters on OS (HR = 0.70 [0.58; 0.83], 2 trials, n = 985) significantly differed from that of β-emitters (HR = 0.96 [0.84; 1.10], n = 4 trials, n = 1096) (interaction p = 0.0041). The overall effect on SSE favoured RI with HR = 0.81 [0.69-0.93] (4 trials, n = 1806) with marked between trial heterogeneity (p = 0.08, I² = 55.3%) and a significant difference (p = 0.02) by the type of RI (α-emitters: HR = 0.65 [0.52-0.82]-2 trials, β-emitters: HR = 0.93 [0.77-1.13]-2 trials). Conclusions: In men with metastatic CRPC a significant improvement of OS and SSE was obtained with bone targeted α-emitter radio isotopes, but not with β-emitter. However, some between trial heterogeneity of effects on OS need further investigations.

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Midzi, Joanah, David W. Jeffery, Ute Baumann, Dimitra L. Capone, Suzy Y. Rogiers e Vinay Pagay. "Evidence of Bi-Directional Volatile-Mediated Communication between Drought-Stressed and Well-Watered Grapevines (Vitis vinifera L.)". Agronomy 13, n. 7 (28 giugno 2023): 1747. http://dx.doi.org/10.3390/agronomy13071747.

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The volatile-mediated interplay between stressed and non-stressed plants has been described in many studies involving both biotic and abiotic stresses as a one-way channel. However, very little is known about the molecular basis and mechanisms by which volatile organic compounds (VOCs) mediate plant communication between drought-stressed ‘emitter’ plants and non-stressed ‘receiver’ neighbours for the defence against impending stress challenges. Aiming to address this in grapevine, this study investigated the effect of two-way VOC exchange between stressed and non-stressed Vitis vinifera L. cv. Shiraz during drought and recovery using four treatments: isolated well-watered (WW) vines, isolated drought-stressed (DS) vines, and co-located DS ‘emitter’ and WW ‘receiver’ vines in a growth room. The results obtained from solid-phase microextraction (SPME) gas chromatography mass spectrometry (GC-MS) analysis showed a synchronised decline in α-pinene concentration in the co-located treatment vines and higher isoprene levels in the DS emitters compared to the isolated DS vines. Targeted gene expression analysis further identified the over-expression of a key gene, allene oxide synthase (AOS), in the jasmonic acid (JA) biosynthesis pathway during peak drought in the DS emitter. Transcript expression of chorismate synthase (CHORS) and α-pinene synthase (VvPNaPin1) showed similar trends in the DS emitter. The results suggest that isoprene and α-pinene may be interplant signalling molecules used by grapevine during drought. To the best of our knowledge, this is the first report of a bi-directional interaction in grapevine between the emitters and receivers under drought stress mediated by the JA and terpenoid biosynthesis pathways.

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Chen, Xueli, Zhengying Wei e Kun He. "An Estimation of the Discharge Exponent of a Drip Irrigation Emitter by Response Surface Methodology and Machine Learning". Water 14, n. 7 (25 marzo 2022): 1034. http://dx.doi.org/10.3390/w14071034.

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The discharge exponent is a general index used to evaluate the hydraulic performance of emitters, which is affected by emitters’ structural parameters. Accurately estimating the effect of change in structural parameters on the discharge exponent is critical for the design and optimization of emitters. In this research, the response surface methodology (RSM) and two machine learning models, the artificial neural network (ANN) and support vector regression (SVR), are used to predict the discharge exponent of tooth-shaped labyrinth channel emitters. The input parameters consist of the number of channel units (N), channel depth (D), tooth angle (α), tooth height (H) and channel width (W). The applied models are assessed through the coefficient of determination (R2), root-mean-square error (RMSE) and mean absolute error (MAE). The analysis of variance shows that tooth height had the greatest effect on the discharge exponent. Statistical criteria indicate that among the three models, the SVR model has the highest prediction accuracy and the best robustness with an average R2 of 0.9696, an average RMSE of 0.0037 and an average MAE of 0.0031. The SVR model can quickly and accurately simulate the discharge exponent of emitters, which is conducive to the rapid design of the emitter.

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Garel, T., J. Blaizot, B. Guiderdoni, D. Schaerer, A. Verhamme e M. Hayes. "Modelling high redshift Lyman α emitters". Monthly Notices of the Royal Astronomical Society 422, n. 1 (12 marzo 2012): 310–25. http://dx.doi.org/10.1111/j.1365-2966.2012.20607.x.

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Bouziotis, P. "BRACHYTHERAPY USING NANOPARTICLES AND α-EMITTERS". Physica Medica 104 (dicembre 2022): S5. http://dx.doi.org/10.1016/s1120-1797(22)03026-5.

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Khostovan, A. A., S. Malhotra, J. E. Rhoads, S. Harish, C. Jiang, J. Wang, I. Wold et al. "Correlations between H α equivalent width and galaxy properties at z = 0.47: Physical or selection-driven?" Monthly Notices of the Royal Astronomical Society 503, n. 4 (17 marzo 2021): 5115–33. http://dx.doi.org/10.1093/mnras/stab778.

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ABSTRACT The H α equivalent width (EW) is an observational proxy for specific star formation rate (sSFR) and a tracer of episodic, bursty star-formation activity. Previous assessments show that the H α EW strongly anticorrelates with stellar mass as M−0.25 similar to the sSFR – stellar mass relation. However, such a correlation could be driven or even formed by selection effects. In this study, we investigate how H α EW distributions correlate with physical properties of galaxies and how selection biases could alter such correlations using a z = 0.47 narrow-band-selected sample of 1572 H α emitters from the Ly α Galaxies in the Epoch of Reionization (LAGER) survey as our observational case study. The sample covers a 3 deg2 area of COSMOS with a survey comoving volume of 1.1 × 105 Mpc3. We assume an intrinsic EW distribution to form mock samples of H α emitters and propagate the selection criteria to match observations, giving us control on how selection biases can affect the underlying results. We find that H α EW intrinsically correlates with stellar mass as W0∝M−0.16 ± 0.03 and decreases by a factor of ∼3 from 107 M⊙ to 1010 M⊙, while not correcting for selection effects steepens the correlation as M−0.25 ± 0.04. We find low-mass H α emitters to be ∼320 times more likely to have rest-frame EW>200 Å compared to high-mass H α emitters. Combining the intrinsic W0–stellar mass correlation with an observed stellar mass function correctly reproduces the observed H α luminosity function, while not correcting for selection effects underestimates the number of bright emitters. This suggests that the W0–stellar mass correlation when corrected for selection effects is physically significant and reproduces three statistical distributions of galaxy populations (line luminosity function, stellar mass function, EW distribution). At lower stellar masses, we find there are more high-EW outliers compared to high stellar masses, even after we take into account selection effects. Our results suggest that high sSFR outliers indicative of bursty star formation activity are intrinsically more prevalent in low-mass H α emitters and not a byproduct of selection effects.

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Nelson, Bryce, Jan Andersson e Frank Wuest. "Targeted Alpha Therapy: Progress in Radionuclide Production, Radiochemistry, and Applications". Pharmaceutics 13, n. 1 (31 dicembre 2020): 49. http://dx.doi.org/10.3390/pharmaceutics13010049.

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This review outlines the accomplishments and potential developments of targeted alpha (α) particle therapy (TAT). It discusses the therapeutic advantages of the short and highly ionizing path of α-particle emissions; the ability of TAT to complement and provide superior efficacy over existing forms of radiotherapy; the physical decay properties and radiochemistry of common α-emitters, including 225Ac, 213Bi, 224Ra, 212Pb, 227Th, 223Ra, 211At, and 149Tb; the production techniques and proper handling of α-emitters in a radiopharmacy; recent preclinical developments; ongoing and completed clinical trials; and an outlook on the future of TAT.

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REN, ZHONGZHOU, e CHANG XU. "THEORETICAL CALCULATIONS ON α-DECAY HALF-LIVES BY THE DENSITY-DEPENDENT CLUSTER MODEL". Modern Physics Letters A 23, n. 27n30 (30 settembre 2008): 2597–603. http://dx.doi.org/10.1142/s0217732308029885.

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The theoretical calculations of α-decay half-lives for three kinds of α-emitters (even-even, even-odd, odd-odd nuclei) are systematically reviewed within the framework of the density-dependent cluster model (DDCM). The half-lives of three typical α-emitters (8 Be , 212 Po , and 270 Ds ) are discussed in detail. The good agreement between experimental and theoretical results shows that DDCM is applicable in the whole mass table from very light nuclei to heavy and superheavy ones.

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Baek, Sunghye, e Andrea Ferrara. "Identifying Lyman α emitters powered by AGNs". Monthly Notices of the Royal Astronomical Society: Letters 432, n. 1 (14 marzo 2013): L6—L10. http://dx.doi.org/10.1093/mnrasl/slt023.

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Baek, S., A. Ferrara e B. Semelin. "Joint Lyman α emitters - quasars reionization constraints". Monthly Notices of the Royal Astronomical Society 423, n. 1 (18 aprile 2012): 774–86. http://dx.doi.org/10.1111/j.1365-2966.2012.20907.x.

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Tesi sul tema "Α-emitters"

Runge, Roswitha, Liane Oehme, Jörg Kotzerke e Robert Freudenberg. "The effect of dimethyl sulfoxide on the induction of DNA strand breaks in plasmid DNA and colony formation of PC Cl3 mammalian cells by alpha-, beta-, and Auger electron emitters 223Ra, 188Re, and 99mTc". Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-214821.

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BACKGROUND: DNA damage occurs as a consequence of both direct and indirect effects of ionizing radiation. The severity of DNA damage depends on the physical characteristics of the radiation quality, e.g., the linear energy transfer (LET). There are still contrary findings regarding direct or indirect interactions of high-LET emitters with DNA. Our aim is to determine DNA damage and the effect on cellular survival induced by (223)Ra compared to (188)Re and (99m)Tc modulated by the radical scavenger dimethyl sulfoxide (DMSO). METHODS: Radioactive solutions of (223)Ra, (188)Re, or (99m)Tc were added to either plasmid DNA or to PC Cl3 cells in the absence or presence of DMSO. Following irradiation, single strand breaks (SSB) and double strand breaks (DSB) in plasmid DNA were analyzed by gel electrophoresis. To determine the radiosensitivity of the rat thyroid cell line (PC Cl3), survival curves were performed using the colony formation assay. RESULTS: Exposure to 120 Gy of (223)Ra, (188)Re, or (99m)Tc leads to maximal yields of SSB (80 %) in plasmid DNA. Irradiation with 540 Gy (223)Ra and 500 Gy (188)Re or (99m)Tc induced 40, 28, and 64 % linear plasmid conformations, respectively. DMSO prevented the SSB and DSB in a similar way for all radionuclides. However, with the α-emitter (223)Ra, a low level of DSB could not be prevented by DMSO. Irradiation of PC Cl3 cells with (223)Ra, (188)Re, and (99m)Tc pre-incubated with DMSO revealed enhanced survival fractions (SF) in comparison to treatment without DMSO. Protection factors (PF) were calculated using the fitted survival curves. These factors are 1.23 ± 0.04, 1.20 ± 0.19, and 1.34 ± 0.05 for (223)Ra, (188)Re, and (99m)Tc, respectively. CONCLUSIONS: For (223)Ra, as well as for (188)Re and (99m)Tc, dose-dependent radiation effects were found applicable for plasmid DNA and PC Cl3 cells. The radioprotection by DMSO was in the same range for high- and low-LET emitter. Overall, the results indicate the contribution of mainly indirect radiation effects for each of the radionuclides regarding DNA damage and cell survival. In summary, our findings may contribute to fundamental knowledge about the α-particle induced DNA damage.

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Runge, Roswitha, Liane Oehme, Jörg Kotzerke e Robert Freudenberg. "The effect of dimethyl sulfoxide on the induction of DNA strand breaks in plasmid DNA and colony formation of PC Cl3 mammalian cells by alpha-, beta-, and Auger electron emitters 223Ra, 188Re, and 99mTc". Springer, 2016. https://tud.qucosa.de/id/qucosa%3A30005.

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Larouze, Alexandre. "Dosimétrie de radioéléments émetteurs alpha pour la radiothérapie interne vectorisée". Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0061.

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La radiothérapie interne vectorisée (RIV) est une technique de traitement du cancer en médecine nucléaire qui consiste à coupler un radionucléide à une molécule vectrice capable de cibler spécifiquement les cellules cancéreuses. Les radionucléides utilisés cliniquement sont majoritairement des émetteurs β− (177Lu,131I, 90Y) ; néanmoins, un émetteur α (223Ra) a récemment été approuvé pour le traitement du cancer de la prostate. L’objectif de cette thèse est de caractériser - par l’intermédiaire d’un code Monte Carlo à structure de trace nommé TILDA-V - les dépôts d’énergie induits par les radio-émetteurs α les plus prometteurs pour la RIV, ainsi que les dommages radio-induits.Dans le cadre de cette thèse, le transport des particules α dans le milieu biologique a tout d’abord été affiné par le développement de nouveaux modèles théoriques implémentés dans TILDA-V. Les prédictions du code en termes de grandeurs caractéristiques macroscopiques (parcours, pouvoir d’arrêt, profils de dose...) ont été comparées aux données expérimentales existant dans la littérature ainsi qu’aux résultats obtenus par le biais d’autres codes de simulation. Dans la majorité des cas, un excellent accord a été observé.Par ailleurs, une étude dosimétrique complète des radio-émetteurs α - incluant des cibles cellulaires isolées et/ou regroupées sous forme de clusters cellulaires - a permis d’évaluer le potentiel thérapeutique des émetteurs α. Une étude comparative avec un large panel d’émetteurs β− (qui ont fait l’objet d’une précédente analyse via TILDA-V) est également reportée dans ce travail.Enfin, le code TILDA-V a été étendu à la modélisation des dommages d’ADN radio-induits via l’implémentation de nouvelles données en termes de sections efficaces pour l’ensemble des interactions induites par ions Heq+ avec les constituants de l’ADN. Dans ce travail, les émetteurs α les plus prometteurs pour la RIV ont ainsi été caractérisés de par leurs propriétés physiques afin d’orienter les médecins nucléaires dans le choix d’un radionucléide de premier choix
Targeted radionuclide therapy (TRT) is a nuclear medicine-based cancer treatment technique that consists in coupling a radionuclide with a carrier molecule able to specifically target cancer cells. In this context, the radionuclides commonly used in clinic are mainly β− emitters (177Lu, 131I, 90Y), although an α-emitter (223Ra) has been recently approved for the treatment of prostate cancer. The current doctoral thesis aims at characterizing the radio-induced energy deposits of the most promising α-emitters for TRT by means of a numerical approach based on a homemade Monte Carlo track structure code named TILDA-V.As part of this thesis, the transport of α-particles in the biological environment was refined by the development of new theoretical models implemented into TILDA-V. The numerical predictions also obtained in terms of range, stopping power, dose profiles were compared with experiments as well as theoretical data provided by existing simulation codes. In most cases, an excellent agreement was observed.Besides, a complete dosimetric study of α-emitters, including isolated single cell targets and/or cell clusters, was provided and compared with other existing predictions. In this context, the therapeutic potential of α-emitters was compared with that of β−-emitters previously studied with TILDA-V.Finally, the TILDA-V code was also extended to the modeling of radiation-induced DNA damages by implementing the cross sections of all the interactions induced by Heq+ ions on DNA components. In this work, the most promising α-emitters for TRT were characterized on the basis of their physical properties in order to guide nuclear medicine physicians in the choice of a radionuclide of first choice

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Capitoli di libri sul tema "Α-emitters"

Laue, Carola A., e David K. Smith. "α-Autoradiography: A Simple Method to Monitor the Migration of α-Emitters in the Environment". In Radioanalytical Methods in Interdisciplinary Research, 121–37. Washington, DC: American Chemical Society, 2003. http://dx.doi.org/10.1021/bk-2004-0868.ch009.

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Kunth, Daniel, Hakim Atek, Göran Östlin, Matthew Hayes, Miguel Mas-Hesse, Claus Leitherer, Artashes Petrosian e Daniel Schaerer. "Local Lyman α Emitters and Their Relevance to High Redshift Ones". In The Impact of HST on European Astronomy, 203–6. Dordrecht: Springer Netherlands, 2009. http://dx.doi.org/10.1007/978-90-481-3400-7_36.

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Mas-Hesse, J. M., D. Kunth, H. Atek, G. Östlin, C. Leitherer, A. Petrosian e D. Schaerer. "Local Lyman α emitters and their relevance to high-redshift star-forming galaxies". In Space Astronomy, 35–38. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-90-481-3006-1_7.

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Geerlings, Maurits W. "Comparison Between β-Emitting Isotopes and α-Emitters Regarding Their Effects on Cancer Cells". In Therapeutic Nuclear Medicine, 781–88. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/174_2012_685.

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Schoeters, G., R. van den HeuveL e O. Vanderborght. "The Study of Damage to Bone Marrow Cells as a Biological Dosimeter after Contamination with Osteotropic α Emitters". In Metals in Bone, 51–61. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-4920-1_5.

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Sethi Chopra, Dimple. "Radiolabelled Nanoparticles for Brain Targeting". In Medical Isotopes. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.92668.

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Tumors like glioblastoma are inaccessible due to blood brain barrier. The permeability of radioisotopes can be improved by conjugating them with nanoparticles. The most common malignant adult brain tumor is glioblastoma, which has very poor patient prognosis. The mean survival for highly proliferative glioblastoma is only 10–14 months despite an aggressive radiotherapy and chemotherapy following debulking surgery. β− particle emitters like 131I, 90Y, 186/188Re, and 177Lu have been coupled with nanoparticles and used for treatment of glioblastoma. These radiopharmaceutical compounds have resulted in a stabilization and improvement of the neurological status with minimal side effects. Similarly, α particle emitters like 213Bi, 211At, and 225Ac are an innovative and interesting alternative. Alpha particles deliver a high proportion of their energy inside the targeted cells within a few micrometers from the emission point versus several millimeters for β− particles. Thus, α particles are highly efficient in killing tumor cells with minimal irradiation of healthy tissues and permits targeting of isolated tumor cells. This has been confirmed by subsequent clinical trials which showed better therapeutic efficacy and minimal side effects, thus opening a new and promising era for glioblastoma medical care using α therapy.

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"α-Radiation Emitter". In Encyclopedia of Metalloproteins, 1833. New York, NY: Springer New York, 2013. http://dx.doi.org/10.1007/978-1-4614-1533-6_100001.

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Abbasi, Akbar, Hesham M.H. Zakaly e Fatemeh Mirekhtiary. "Radium-223 and Actinium-225 α-Emitter Radiopharmaceuticals in Treatment of Metastatic Castration-Resistant Prostate Cancer". In Radiopharmaceuticals - Current Research for Better Diagnosis and Therapy. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.99756.

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In recent decades, multiple radiopharmaceutical conjugates have been tested and shown to be efficacious in treating metastasized castration-resistant prostate cancer (mCRPC). Several types of research have been published on the therapeutic use of α-emitter radiopharmaceuticals, and several authors suggested their treatment superiority. One of the suggested methods is targeted alpha therapy. In this method, alpha radiation delivers energy to cancer cells and the tumor microenvironment while minimizing toxicity to surrounding tissues. In this chapter, the alpha emitter radiopharmaceutical applications in castration-resistant prostate cancer patients were investigated. Hence, we studied the 223Ra and 225Ac α-emitter radiopharmaceuticals application method and distribution of dose throughout human body organs.

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Atti di convegni sul tema "Α-emitters"

Wang, Junxian. "On the Nature of Lyman-α Emitters". In THE EMERGENCE OF COSMIC STRUCTURE: Thirteenth Astrophysics Conference. AIP, 2003. http://dx.doi.org/10.1063/1.1581803.

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Inoue, Akio K. "A possible signature of primordial stellar populations in z = 3 Lyman α emitters". In FIRST STARS IV – FROM HAYASHI TO THE FUTURE –. AIP, 2012. http://dx.doi.org/10.1063/1.4754344.

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Bingham, C. R., J. Wauters, B. E. Zimmerman, K. S. Toth, J. C. Batchelder, E. F. Zganjar, D. J. Blumenthal et al. "Investigation of short-lived PT and PB α emitters near the proton drip line". In The fourteenth international conference on the application of accelerators in research and industry. AIP, 1997. http://dx.doi.org/10.1063/1.52706.

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Lara-Robustillo, Esperanza, e Marina Rodri´guez Alcala´. "Comparison of Actinides Separation by Coprecipitation and Chromatographic Resin (Dipex®) for Gross Alpha Determination". In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16249.

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The determination of gross alpha in wastes that have alpha, beta and gamma emitters is important from a regulatory point of view. The level of alpha radioactivity allowed is limited in a low and medium level radioactive location for safety reasons, so it is necessary to measure it with high precision. In order to quantify the concentration of alpha emitters it is necessary to perform an adequate radiochemical separation before measurement. In this paper has been studied and compared the results obtained by two separation methods: one by coprecipitation using BaSO4, Fe(OH)3 and/or CaC2O4 as precipitant agents and the other one by extraction chromatography using Actinide Resin (Dipex®). The separation procedures have been applied to spent ion exchange resins from Spanish Nuclear Power Plants. Once the sample was dissolved by acid digestion in a closed vessel microwave equipment, and the radionuclides of interest were isolated of the rest by the techniques before mentioned, the gross alpha was measured by Liquid Scintillation Counting (LSC), using the α/β discrimination if necessary (when the separation was not completed), since this technique is today one of the most used and accurate for measuring radioactivity because LS spectrometry can detect practically all types of radiation with high efficiency.

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Forbes, Richard G. "Using the parameter "formal area efficiency" (α_f ^SN) to analyze current-voltage measurements on large-area field electron emitters". In 2021 34th International Vacuum Nanoelectronics Conference (IVNC). IEEE, 2021. http://dx.doi.org/10.1109/ivnc52431.2021.9600797.

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Rondinella, V. V., T. Wiss, J. P. Hiernaut e J. Cobos. "Studies on Spent Fuel Alterations During Storage and Radiolysis Effects on Corrosion Behaviour Using Alpha-Doped UO2". In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4593.

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UO2 containing different fractions of short-lived alpha-emitters, the so-called alpha-doped UO2 simulates the level of activity of spent fuel after different storage times, and can be used to study the effects of radiolysis on the corrosion behaviour of aged spent fuel exposed to groundwater in a geologic repository. Furthermore, the integral over time of the alpha-decay in alpha-doped UO2 can simulate the decay damage accumulated in spent fuel during storage. This allows investigating property modifications occurring to the fuel during storage periods of interest (e.g. in view of spent fuel retrieval or in view of final disposal) within a laboratory-acceptable timescale. Periodical measurements of lattice parameter are performed on high activity alpha-doped UO2 to investigate the build-up of radiation damage and evaluate possible dose rate effects. Additionally, annealing tests combined with He-release measurements using a Knudsen cell and with microstructure examination using TEM are performed to establish a correlation among the annealing of damage in the microstructure (mainly characterized by dislocation loops) and the release behaviour of He. The effects on the microstructure due to the accumulation of He and α-decay damage are of interest as they may considerably affect the mechanical integrity of the fuel rods, by causing e.g. swelling or cracking in the fuel and/or overpressurization of the cladding. Alpha-doped UO2 with specific activities spanning over three orders of magnitude and undoped UO2 were used in static leaching experiments at room temperature in deionized water under nominally anoxic conditions. Under these experimental conditions (single effect studies) a clear dissolution enhancing effect of alpha-radiolysis was observed coupled with the establishment of higher redox potential due to the radiolytic process. An alpha-activity dependence of the dissolution behaviour was observed.

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Pearson, Jeremy, George Miller e Mikael Nilsson. "High Linear Energy Transfer Degradation Studies Simulating Alpha Radiolysis of TRU Solvent Extraction Processes". 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/icem2013-96365.

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Treatment of used nuclear fuel through solvent extraction separation processes is hindered by radiolytic damage from radioactive isotopes present in used fuel. The nature of the damage caused by the radiation may depend on the radiation type, whether it be low linear energy transfer (LET) such as gamma radiation or high LET such as alpha radiation. Used nuclear fuel contains beta/gamma emitting isotopes but also a significant amount of transuranics which are generally alpha emitters. Studying the respective effects on matter of both of these types of radiation will allow for accurate prediction and modeling of process performance losses with respect to dose. Current studies show that alpha radiation has milder effects than that of gamma. This is important to know because it will mean that solvent extraction solutions exposed to alpha radiation may last longer than expected and need less repair and replacement. These models are important for creating robust, predictable, and economical processes that have strong potential for mainstream adoption on the commercial level. The effects of gamma radiation on solvent extraction ligands have been more extensively studied than the effects of alpha radiation. This is due to the inherent difficulty in producing a sufficient and confluent dose of alpha particles within a sample without leaving the sample contaminated with long lived radioactive isotopes. Helium ion beam and radioactive isotope sources have been studied in the literature. We have developed a method for studying the effects of high LET radiation in situ via 10B activation and the high LET particles that result from the 10B(n,α)7Li reaction which follows. Our model for dose involves solving a partial differential equation representing absorption by 10B of an isentropic field of neutrons penetrating a sample. This method has been applied to organic solutions of TBP and CMPO, two ligands common in TRU solvent extraction treatment processes. Rates of degradation of TBP and CMPO and their respective degradation products in the presence of high LET radiation are presented and discussed. These results are also compared to gamma studies performed in our lab and other gamma and alpha studies found in the literature. The possible application of this method to a variety of other solvent extraction ligands to study the effects of high LET radiation is also considered.

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Mattar, F. P., e P. R. Berman. "Coherent pump dynamics, depletion, and transverse effects on the superfluorescence/Stokes/probe (SF, St, Prb) beam buildup and its asymptotic evolution of a stabilized on-axis swept-gain Raman forward amplifiers/spectroscopy studies". In International Laser Science Conference. Washington, D.C.: Optica Publishing Group, 1986. http://dx.doi.org/10.1364/ils.1986.thc6.

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A computer movie illustrating a rigorous multimode calculation of SF, St, Prb buildup in Raman studies is presented. This coherent copropagational study based on Maxwell-Bloch formalism1 includes phase and transverse variations, nonlinear asymmetric dispersion, pump spatial depletion, and time-dependent variations in population inversion density. Theλ scheme is selected so that the active transitions are optically thick for both the pump (α p l > 5) and the SF (α sf l > 35) pulses. This choice of Beer lengths, i.e., of oscillator strengths, insures that the two pulses never cease to overlap and optimizes the SF initially small signal growth. The pump interacts like a self-induced transparency while the SF, St, Prb evolves as a small-area in a two-level emitter which can be described as a nonlinear pendulum in the pane wave. For a given ratio of Beer lengths, distinct Fresnel numbers, atomic density numbers, small signal SF, St, Prb time-integrated energy stabilization or self-focusing may arise, as observed experimentally. For a sufficiently larger propagation distance, an asymptotic evolution of a quasisolitary nonhyperbolic-secant pulse of constant area is reported.

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D’Avanzo, P., Nobuyuki Kawai e Shigehiro Nagataki. "The afterglow and host galaxy of GRB 090205: evidence for a Ly-α emitter at z = 4.65". In DECIPHERING THE ANCIENT UNIVERSE WITH GAMMA-RAY BURSTS. AIP, 2010. http://dx.doi.org/10.1063/1.3509252.

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Coltella, Thomas, Matteo Di Prinzio, Maurizio Lazzaretti, Luciano Giorgi, Gabriele Firpo, Francesco Orzelli, Michele Frignani, Monica Linda Frogheri e Cristina Ricci. "CONTAS: Design and Qualification of a High Integrity Container for Intermediate Level Solid Waste". In ASME 2023 International Conference on Environmental Remediation and Radioactive Waste Management. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/icem2023-110225.

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Abstract Ansaldo Nucleare S.p.A. has designed, fabricated and qualified a high integrity container, CONTAS, for the conditioning, transportation and long term storage of solid ILW with low content of α-emitter radionuclides. CONTAS is a carbon steel forged cylindrical container 1500mm high by 1100mm in external diameter, offering a general shielding wall thickness of 160mm and an internal usable volume of approximately 0,5m3. Based on national and international norms and standards, CONTAS complies with stringent requirements to ensure protection of persons and environment: • UNI 11784 [1] (the reference norm in Italy for solid heterogenous ILW conditioning and storage) • IAEA SSR-6 [3] as Type IP-3 package • Raccolta V.S.R. [7] as pressure equipment for nuclear purpose CONTAS design, within the scope of a proper defined Qualification Plan, has been successfully qualified through a mix of experimental and analytical tests, performed on material samples, full-scale prototypes, FEM models, arranging the test sites in compliance with the criteria defined by standards and involving qualified Suppliers and Laboratories. The experimental tests include free drop tests, thermal test, degradation tests, leak tightness tests, pressure test, functional tests. Several innovative elements of CONTAS, especially concerning the sealing systems, are currently patent pending.

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