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400 results on '"Balestra, C."'

51. The use of portable 2D echocardiography and 'frame-based' bubble counting as a tool to evaluate diving decompression stress

Author

Germonpré, P., Papadopoulou, V., Hemelryck, W., Obeid, G., Lafère, P., Robert Eckersley, Tang, M. -X, Balestra, C., Body Composition and Morphology, and Experimental Anatomy

Subjects
musculoskeletal diseases, DEEP STOP, Time Factors, HYPERBARIC DECOMPRESSION, Diving, Point-of-Care Systems, Video Recording, Hygiène et médecine sportives, decompression sickness, WEIGHTED KAPPA, venous gas embolism, Veins, bubbles, diving research, Embolism, Air, Humans, Public, Environmental & Occupational Health, Observer Variation, Science & Technology, Embolism, Air/diagnostic imaging, Doppler, Education physique, Médecine pathologie humaine, Decompression Sickness/classification, risk assessment, Reproducibility of Results, Informatique médicale, Sciences bio-médicales et agricoles, VENOUS GAS-BUBBLES, Sciences biomédicales, DIVERS, Video Recording/statistics & numerical data, Echocardiography, AGREEMENT, PUBLIC, ENVIRONMENTAL & OCCUPATIONAL HEALTH, SCI, RELIABILITY, Médecine de l'environnement, arterial gas embolism, Echocardiography/instrumentation, 82 FSW, FORAMEN OVALE, human activities, Life Sciences & Biomedicine, INTRACLASS CORRELATION-COEFFICIENT, Algorithms
Abstract

'Decompression stress' is commonly evaluated by scoring circulating bubble numbers post dive using Doppler or cardiac echography. This information may be used to develop safer decompression algorithms, assuming that the lower the numbers of venous gas emboli (VGE) observed post dive, the lower the statistical risk of decompression sickness (DCS). Current echocardiographic evaluation of VGE, using the Eftedal and Brubakk method, has some disadvantages as it is less well suited for large-scale evaluation of recreational diving profiles. We propose and validate a new 'frame-based' VGE-counting method which offers a continuous scale of measurement., Journal Article, info:eu-repo/semantics/published

Published
2014

53. Inquinamento elettro-magnetico nel comprensorio di Otranto

Author

LATORRE O, MARRA A. C, BALESTRA C, PICCINNO G, CARROZZINI F, BRUNI F, GABUTTI G., DE DONNO, Maria Antonella, Latorre, O, MARRA A., C, DE DONNO, Maria Antonella, Balestra, C, Piccinno, G, Carrozzini, F, Bruni, F, and Gabutti, G.

Published
2001

59. Supernova remnants and pulsar wind nebulae as seen by the MAGIC Cherenkov Telescope

Author

de Cea Del Pozo, Elsa, Anderhub, Antonelli, H., L. A., Antoranz, Backes, P., Baixeras, M., Balestra, C., Barrio, S., J. A., Bastieri, Becerra, Gonzalez, Becker, J., J. K., Bednarek, Berger, W., Bernardini, K., Biland, E., Bock, A., R. K., Bonnoli, Bordas, G., Borla, Tridon, Bosch, Ramon, Bose, V., Braun, D., Bretz, I., Britzger, T., Camara, D., Carmona, M., Carosi, E., Colin, A., Commichau, P., Contreras, S., J. L., Cortina, Costado, J., M. T., Covino, Dazzi, S., Angelis, De, de Los Reyes, Lotto, De, Maria, De, Sabata, De, Delgado, Mendez, Dominguez, C., Dominis, Prester, Dorner, D., Doro, D., Elsaesser, M., Errando, D., Ferenc, M., Fernandez, D., Firpo, E., Fonseca, R., M. V., Font, Galante, L., Garcia, Lopez, R. J., Garczarczyk, Gaug, M., Godinovic, M., Goebel, N., Hadasch, F., Herrero, D., Hildebrand, A., Hoehne, Moench, Hose, D., Hrupec, J., Hsu, D., C. C., Jogler, Klepser, T., Kranich, S., Barbera, La, Laille, A., Leonardo, A., Lindfors, E., Lombardi, E., Longo, S., Lopez, F., Lorenz, M., Majumdar, E., Maneva, P., Mankuzhiyil, G., Mannheim, N., Maraschi, K., Mariotti, L., Martinez, M., Mazin, M., Meucci1, D., Miranda, M., J. M., Mirzoyan, Miyamoto, R., Moldon, H., Moles, J., Moralejo, M., Nieto, A., Nilsson, D., Ninkovic, K., Orito, J., Oya, R., Paoletti, I., Paredes, R., J. M., Pasanen, Pascoli, M., Pauss, D., Pegna, F., R. G., Perez, Torres, M. A., Persic, Peruzzo, M., Prada, L., PRADA MORONI, PIER GIORGIO, Prandini, E., Puchades, N., Puljak, I., Reichardt, I., Rhode, W., Ribo, M., Rico, J., Rissi, M., Rugamer, S., Saggion, A., Saito, T. Y., Salvati, M., Sanchez, Conde, Satalecka, M., Scalzotto, K., Scapin, V., Schweizer, V., Shayduk, T., Shore, STEVEN NEIL, S. N., Sierpowska, Bartosik, Sillanpaa, A., Sitarek, A., Sobczynska, J., Spanier, D., Spiro, F., Stamerra, S., Stark, A., L. S., Suric, Takalo, T., Tavecchio, L., Temnikov, F., Tescaro, P., Teshima, D., Torres, M., D. F., Turini, Vankov, N., Wagner, H., R. M., Zabalza, Zandanel, V., Zanin, F., Zapatero, R., and Magic, Collaboration

Published
2010

60. A box-model approach for a snapshot of Carbon biogeochemical cycle in the northern Adriatic Sea during February 2008

Author

Catalano G., Azzaro M., Balestra C., Bastianini M., Bellucci L., Bernardi Aubry F., Burca M., Cantoni C., Caruso G., Casotti R., Cataletto B., Cozzi S., Del Negro P., Focaccia P., Fonda Umani S., Frignani M., Giani M., Giuliani S., Kovacevic V., La Ferla R., Langone L., Luchetta A., Maimone G., Malisana E., Monticelli L.S., Piacentino S., Pugnetti A., Ramazzo F., Ravaioli M., Socal G., Spagnoli F., and Ursella L.

Published
2010

63. Inducing HSP for Protection against DCS: Heat Exposure before Diving Reduces Bubble Formation in Man

Author

Blatteau, Jean-Eric, Gempp, Emmanuel, Pontier, Jm, Balestra, C., Mets, Tony, Germonpre, Peter, Gerontology, and Frailty in Ageing

Subjects
NITRIC-OXIDE, exercise, decompression-sickness, PLASMA-VOLUME, survival, hydration, DIVE, RATS, VASODILATION
Abstract

Heat stress is a nonpharmacological preconditioning strategy which can lead to protection against various types of subsequent insults, such as ischemia, hypoxia, inflammation, drugs, and even bubble-induced injury from decompression. It has been suggested that the protective effect of heat exposure against DCS in rats could be related to biochemical processes involving heat shock proteins (HSP) of the 70-kDa range. The purpose of this study was to determine the efficacy of sauna-induced heat exposure prior to a simulated dive on bubble reduction and to examine the adjustments in Hsp70 concentration and hemodynamic parameters. Sixteen divers were compressed in a hyperbaric chamber to 400 kPa for 25 min and decompressed at a rate of 100 kPa. min(-1) with a 4 min stop at 130 kPa. Each diver performed two dives, one with and one without pre-dive FIR dry sauna session for 30 min at 65 degrees C, ending I hour prior to the dive. Brachial artery flow mediated dilation (FMD), blood pressure, and bodyweight measurements were taken before and after the sauna session along with blood samples for analysis of plasma volume, protein concentrations, plasma osmolality, and plasma Hsp70. Circulating venous bubbles were detected with a precordial Doppler after surfacing. This study shows that a single pre-dive sauna session significantly decreases circulating bubbles after a chamber dive. Plasma Hsp70 significantly increased 2 h after sauna completion. The sauna session led to an extracellular dehydration, resulting in hypovolemia and bodyweight loss. A significant rise in FMD and a reduction in systolic blood pressure and pulse pressure were observed. Inducing HSP from heat stress could offer a new way of reducing decompression sickness risk. Sweat dehydration and NO pathway could be also involved in this protective effect. Further investigation is required to elucidate the preponderant mechanism underlying this heat exposure induced reduction in bubble formation.

Published
2009

64. A box-model approach for a snapshot of Carbon biogeochemical cycle in the northern Adriatic Sea

Author

Catalano G., Balestra C., Bastianini M., Bellucci L., Bernardi Aubry F., Burca M., Cantoni C., Caruso G., Casotti R., Cataletto B., Cozzi S., Del Negro P., Fonda Umani S., Giani M., Giuliani S., Kovacevic V., La Ferla R., Langone L., Luchetta A., Monticelli L., Piacentino S., Pugnetti A., Ramazzo F., Ravaioli M., Socal G., Spagnoli F., and Tirelli V.

Published
2009

78. A ternary model of decompression sickness in rats

Author

Buzzacott, Peter, Lambrechts, K., Mazur, A., Wang, Q., Papadopoulou, V., Theron, M., Balestra, C., Guerrero, F., Buzzacott, Peter, Lambrechts, K., Mazur, A., Wang, Q., Papadopoulou, V., Theron, M., Balestra, C., and Guerrero, F.

Abstract

© 2014 Elsevier Ltd. Background: Decompression sickness (DCS) in rats is commonly modelled as a binary outcome. The present study aimed to develop a ternary model of predicting probability of DCS in rats, (as no-DCS, survivable-DCS or death), based upon the compression/decompression profile and physiological characteristics of each rat. Methods: A literature search identified dive profiles with outcomes no-DCS, survivable-DCS or death by DCS. Inclusion criteria were that at least one rat was represented in each DCS status, not treated with drugs or simulated ascent to altitude, that strain, sex, breathing gases and compression/decompression profile were described and that weight was reported. A dataset was compiled (. n=1602 rats) from 15 studies using 22 dive profiles and two strains of both sexes. Inert gas pressures in five compartments were estimated. Using ordinal logistic regression, model-fit of the calibration dataset was optimised by maximum log likelihood. Two validation datasets assessed model robustness. Results: In the interpolation dataset the model predicted 10/15 cases of nDCS, 3/3 sDCS and 2/2 dDCS, totalling 15/20 (75% accuracy) and 18.5/20 (92.5%) were within 95% confidence intervals. Mean weight in the extrapolation dataset was more than 2. SD outside of the calibration dataset and the probability of each outcome was not predictable. Discussion: This model is reliable for the prediction of DCS status providing the dive profile and rat characteristics are within the range of parameters used to optimise the model. The addition of data with a wider range of parameters should improve the applicability of the model.

Published
2014

79. DIALYSIS CARDIOVASCULAR COMPLICATIONS 1

Author

Wheeler, D. C., primary, Abdalla, S., additional, Chertow, G., additional, Parfrey, P., additional, Herzog, C., additional, Mikolasevic, I., additional, Racki, S., additional, Lukenda, V., additional, Milic, S., additional, Devcic, B., additional, Orlic, L., additional, Suttorp, M. M., additional, Hoekstra, T., additional, Ocak, G., additional, Van Diepen, A. T. N., additional, Ott, I., additional, Mittelman, M., additional, Rabelink, T. J., additional, Krediet, R. T., additional, Dekker, F. W., additional, Simone, S., additional, Dell'Oglio, M. P. S., additional, Ciccone, M., additional, Corciulo, R., additional, Castellano, G., additional, Balestra, C., additional, Grandaliano, G., additional, Gesualdo, L., additional, Pertosa, G., additional, Nishida, M., additional, Ando, M., additional, Karasawa, K., additional, Iwamoto, Y., additional, Tsuchiya, K., additional, Nitta, K., additional, Krzanowski, M., additional, Janda, K., additional, Gajda, M., additional, Dumnicka, P., additional, Fedak, D., additional, Lis, G., additional, Ja kowski, P., additional, Litwin, J. A., additional, Su owicz, W., additional, Freitas, G. R., additional, Silva, V. B., additional, Abensur, H., additional, Luders, C., additional, Pereira, B. J., additional, Castro, M. C., additional, Oliverira, R. B., additional, Moyses, R. M., additional, Elias, R. M., additional, Silva, B. C., additional, Tekce, H., additional, Ozturk, S., additional, Aktas, G., additional, Kin Tekce, B., additional, Erdem, A., additional, Ozyasar, M., additional, Taslamacioglu Duman, T., additional, Yazici, M., additional, Kirkpantur, A., additional, Balci, M. M., additional, Turkvatan, A., additional, Afsar, B., additional, Alkis, M., additional, Mandiroglu, F., additional, Voroneanu, L., additional, Siriopol, D., additional, Nistor, I., additional, Apetrii, M., additional, Hogas, S., additional, Onofriescu, M., additional, Covic, A., additional, An, W. S., additional, Kim, S. E., additional, Son, Y. K., additional, Oh, Y. J., additional, Gelev, S., additional, Toshev, S., additional, Trajceska, L., additional, Selim, G., additional, Dzekova, P., additional, Shikole, A., additional, Park, J., additional, Lee, J. S., additional, Shin, E.-S., additional, Ann, S. H., additional, Kim, S.-J., additional, Chung, H. C., additional, Sulowicz, W., additional, Elewa, U., additional, Bichari, W., additional, Abo-Seif, K., additional, Seferi, S., additional, Rroji, M., additional, Likaj, E., additional, Spahia, N., additional, Barbullushi, M., additional, Thereska, N., additional, Kopecky, C. M., additional, Genser, B., additional, Maerz, W., additional, Wanner, C., additional, Saemann, M. D., additional, Weichhart, T., additional, Sezer, S., additional, Gurlek Demirci, B., additional, Tutal, E., additional, Bal, Z., additional, Erkmen Uyar, M., additional, Ozdemir Acar, F. N., additional, Macunluoglu, B., additional, Atakan, A., additional, Ari Bakir, E., additional, Georgianos, P., additional, Sarafidis, P. A., additional, Stamatiadis, D. N., additional, Liakopoulos, V., additional, Zebekakis, P. E., additional, Papagianni, A., additional, Lasaridis, A. N., additional, Eftimovska - Otovic, N., additional, Babalj-Banskolieva, E., additional, Kostadinska-Bogdanoska, S., additional, Grozdanovski, R., additional, Aono, M., additional, Sato, Y., additional, El Amrani, M., additional, Asserraji, M., additional, Benyahia, M., additional, Lee, Y.-K., additional, Choi, S. R., additional, Cho, A., additional, Kim, J.-K., additional, Choi, M.-J., additional, Kim, S. J., additional, Yoon, J.-W., additional, Koo, J.-R., additional, Kim, H. J., additional, Noh, J.-W., additional, Inagaki, H., additional, Yokota, N., additional, Chiyotanda, S., additional, Fukami, K., additional, Fujimoto, S., additional, Kendi Celebi, Z., additional, Kutlay, S., additional, Sengul, S., additional, Nergizoglu, G., additional, Erturk, S., additional, Ates, K., additional, Vishnevskii, K. A., additional, Rumyantsev, A. S., additional, Zemchenkov, A. Y., additional, Smirnov, A. V., additional, Reinhardt, B., additional, Knaup, R., additional, Esteve Simo, V., additional, Carneiro Oliveira, J., additional, Moreno Guzman, F., additional, Fulquet Nicolas, M., additional, Pou Potau, M., additional, Saurina Sole, A., additional, Duarte Gallego, V., additional, Ramirez De Arellano Serna, M., additional, Turkmen, K., additional, Demirtas, L., additional, Akbas, E. M., additional, Bakirci, E. M., additional, Buyuklu, M., additional, Timuroglu, A., additional, Georgianos, P. I., additional, Karpetas, A., additional, Taira, T., additional, Nohtomi, K., additional, Takemura, T., additional, Chiba, T., additional, Hirano, T., additional, Chang, C.-T., additional, Huang, C.-C., additional, Chen, C.-J., additional, Mohamed, A., additional, Kanai, H., additional, Tamura, Y., additional, Kaizu, Y., additional, Kali, A., additional, Yayar, O., additional, Erdogan, B., additional, Eser, B., additional, Ercan, Z., additional, Buyukbakkal, M., additional, Merhametsiz, O., additional, Haspulat, A., additional, Yildirim, T., additional, Bozkurt, B., additional, Ayli, M. D., additional, Gokustun, D., additional, Markaki, A., additional, Grammatikopoulou, M., additional, Fragkiadakis, G., additional, Stylianou, K., additional, Venyhaki, M., additional, Chatzi, V., additional, Stojceva-Taneva, O., additional, Tozija, L., additional, Dzekova-Vidimliski, P., additional, Petronievic, Z., additional, Sikole, A., additional, Moyseyenko, V., additional, Nykula, T., additional, Fernandes, R. T., additional, Barreto, D. V., additional, Rodrigues, G. G. C., additional, Misael, A., additional, Branco-Martins, C. T., additional, and Barreto, F. C., additional

Published
2014
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81. EPO modulation in a 14-days undersea scuba dive

Author

Revelli, L, Vagnoni, S, D'Amore, A, Di Stasio, Enrico, Lombardi, Celestino Pio, Storti, G, Proietti, R, Balestra, C, Ricerca, Bm, Di Stasio, Enrico (ORCID:0000-0003-1047-4261), Lombardi, Cp (ORCID:0000-0001-8910-6693), Revelli, L, Vagnoni, S, D'Amore, A, Di Stasio, Enrico, Lombardi, Celestino Pio, Storti, G, Proietti, R, Balestra, C, Ricerca, Bm, Di Stasio, Enrico (ORCID:0000-0003-1047-4261), and Lombardi, Cp (ORCID:0000-0001-8910-6693)

Abstract

Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O2 administration in pre-surgical patients or in some anemic disease.

Published
2013

82. EPO modulation in a 14-days undersea scuba dive

Author

Revelli, Luca, Vagnoni, Salvatore, D'Amore, Annamaria, Di Stasio, Enrico, Lombardi, Celestino Pio, Storti, Gabriele, Proietti, Rodolfo, Balestra, C, Ricerca, Bianca Maria, Revelli, Luca (ORCID:0000-0003-1907-773X), Vagnoni, Salvatore (ORCID:0000-0002-8600-6424), Di Stasio, Enrico (ORCID:0000-0003-1047-4261), Lombardi, Celestino Pio (ORCID:0000-0001-8910-6693), Proietti, Rodolfo (ORCID:0000-0003-1137-9928), Ricerca, Bianca Maria (ORCID:0000-0002-0791-824X), Revelli, Luca, Vagnoni, Salvatore, D'Amore, Annamaria, Di Stasio, Enrico, Lombardi, Celestino Pio, Storti, Gabriele, Proietti, Rodolfo, Balestra, C, Ricerca, Bianca Maria, Revelli, Luca (ORCID:0000-0003-1907-773X), Vagnoni, Salvatore (ORCID:0000-0002-8600-6424), Di Stasio, Enrico (ORCID:0000-0003-1047-4261), Lombardi, Celestino Pio (ORCID:0000-0001-8910-6693), Proietti, Rodolfo (ORCID:0000-0003-1137-9928), and Ricerca, Bianca Maria (ORCID:0000-0002-0791-824X)

Abstract

Erythropoiesis is affected during deep saturation dives. The mechanism should be related to a downregulation of serum Erythropoietin (s-EPO) concentration or to a toxic effect of the hyperbaric hyperoxia. We evaluated s-EPO and other haematological parameters in 6 scuba divers before, during and after a 14-days guinness saturation dive (8-10 m). Athletes were breathing air at 1.8-2 ATA, under the control of a team of physicians. Serum parameters were measured before diving (T0) and: 7 days (T1), 14 days (T2) after the beginning of the dive and 2 h (T3) and 24 h (T4) after resurfacing. Hgb, and many other haematological parameters did not change whereas Ht, s-EPO, the ratio between s-EPO predicted and that observed and reticulocytes (absolute, percent) declined progressively from T0 to T3. At T4 a significant rise in s-EPO was observed. Hgb did not vary but erythropoiesis seemed to be affected as s-EPO and reticulocyte counts showed. All these changes were statistically significant. The experiment, conducted in realistic conditions of dive length, oxygen concentration and pressure, allows us to formulate some hypotheses about the role of prolonged hyperbarism on erythropoiesis. The s-EPO rise, 24 h after resurfacing, is clearly documented and related to the "Normobaric Oxygen Paradox". This evidence suggests interesting hypotheses for new clinical applications such as modulation of s-EPO production and Hgb content triggered by appropriate O2 administration in pre-surgical patients or in some anemic disease.

Published
2013

85. EPO Modulation in a 14-Days Undersea Scuba Dive

Author

Revelli, L., additional, Vagnoni, S., additional, D'Amore, A., additional, Di Stasio, E., additional, Lombardi, C., additional, Storti, G., additional, Proietti, R., additional, Balestra, C., additional, and Ricerca, B., additional

Published
2013
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86. A red orange extract modulates the vascular response to a recreational dive: a pilot study on the effect of anthocyanins on the physiological consequences of scuba diving.

Author

Balestra, C., Cimino, F., Theunissen, S., Snoeck, T., Provyn, S., Canali, R., Bonina, A., and Virgili, F.

Abstract

Nutritional antioxidants have been proposed as an expedient strategy to counter the potentially deleterious effects of scuba diving on endothelial function, flow-mediated dilation (FMD) and heart function. Sixteen volunteers performing a single standard dive (20 min at 33 m) according to US Navy diving procedures were randomly assigned to two groups: one was administered with two doses of 200 mg of an anthocyanins (AC)-rich extract from red oranges, 12 and 4 h before diving. Anthocyanins supplementation significantly modulated the effects of diving on haematocrit, body water distribution and FMD. AC administration significantly reduces the potentially harmful endothelial effects of a recreational single dive. The lack of any significant effect on the most common markers of plasma antioxidant capacity suggests that the mechanism underlying this protective activity is independent of the putative antioxidant effect of AC and possibly involves cellular signalling modulation of the response to high oxygen. [ABSTRACT FROM PUBLISHER]

Published
2016
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92. Telemetrické meranie potkanov počas experimentálnych ponorov v hyperbarickej komore - pilotná štúdia.

Author

Rozložník, M., Molčan, L., Svitok, P., Balestra, C., and Zeman, M.

Abstract

Copyright of Occupational Medicine / Pracovní Lékarství is the property of Czech Medical Association of JE Purkyne and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2018

96. High efficiency thermionic converter studies

Author

Huffman, F. N, Sommer, A. H, Balestra, C. L, Briere, T. R, Lieb, D, Oettinger, P. E, and Goodale, D. B

Subjects
Energy Production And Conversion
Abstract

Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion.

Published
1977

97. Thermionic converter performance with oxide collectors

Author

Lieb, D, Goodale, D, Briere, T, and Balestra, C

Subjects
Energy Production And Conversion
Abstract

Thermionic converters using a variety of metal oxide collector surfaces have been fabricated and tested. Both work function and power output data are presented and evaluated. Oxides of barium, strontium, zinc, tungsten and titanium have been incorporated into a variable spacing converter. Tungsten oxide was found to give the highest converter performance and to furnish oxygen for the emitter at the same time. Oxygenated emitters operate at reduced cesium pressure with an increase in electrode spacing. Electron spectroscopy for chemical analysis (ESCA) performed on several tungsten oxide collectors showed cesium penetration of the oxide layer, possibly forming a cesium tungstate bronze. Titanium oxide showed high performance but did not furnish oxygen for the emitter; strontium oxide, in the form of a sprayed layer, appeared to dissociate in the presence of cesium. Sprayed coatings of barium and zinc oxides produced collector work functions of about 1.3 eV, but had excessive series resistance. Lanthanum hexaboride, in combination with oxygen introduced through a silver tube, and cesium produced a low work function collector and better than average performance.

Published
1977

98. High efficiency thermionic converter studies

Author

Huffman, F. N, Sommer, A. H, Balestra, C. L, Briere, D. P, and Oettinger, P. E

Subjects
Nuclear And High-Energy Physics
Abstract

The objective is to improve thermionic converter performance by means of reduced interelectrode losses, greater emitter capabilities, and lower collector work functions until the converter performance level is suitable for out-of-core space reactors and radioisotope generators. Electrode screening experiments have identified several promising collector materials. Back emission work function measurements of a ZnO collector in a thermionic diode have given values less than 1.3 eV. Diode tests were conducted over the range of temperatures of interest for space power applications. Enhanced mode converter experiments have included triodes operated in both the surface ionization and plasmatron modes. Pulsed triodes were studied as a function of pulse length, pulse potential, inert gas fill pressure, cesium pressure, spacing, emitter temperature and collector temperature. Current amplifications (i.e., mean output current/mean grid current) of several hundred were observed up to output current densities of one amp/sq cm. These data correspond to an equivalent arc drop less than 0.1 eV.

Published
1976

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