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Thomas B. Mccord - One of the best experts on this subject based on the ideXlab platform.
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Hydrated Salt Minerals on Ganymede's Surface: Evidence of an Ocean Below
Science (New York N.Y.), 2001Co-Authors: Thomas B. Mccord, Gary B. Hansen, Charles A. HibbittsAbstract:Reflectance spectra from Galileo's near-infrared mapping spectrometer (NIMS) suggests that the surface of Ganymede, the largest satellite of Jupiter, contains Hydrated materials. These materials are interpreted to be similar to those found on Europa, that is, mostly frozen magnesium sulfate brines that are derived from a subsurface briny layer of fluid.
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thermal and radiation stability of the Hydrated Salt minerals epsomite mirabilite and natron under europa environmental conditions
Journal of Geophysical Research, 2001Co-Authors: Thomas B. Mccord, Thomas M. Orlando, Glenn Teeter, M. T. Sieger, Nikolay G. Petrik, G B Hansen, Lisa Van KeulenAbstract:We report studies on the thermal and radiolytic stability of the Hydrated Salt minerals epsomite (MgSO4·7H2O), mirabilite (Na2SO4·10H2O), and natron (Na2CO3·10H2O) under the low-temperature and ultrahigh vacuum conditions characteristic of the surface of the Galilean satellite Europa. We prepared samples, ran temperature-programmed dehydration (TPD) profiles and irradiated the samples with electrons. The TPD profiles are fit using Arrhenius-type first-order desorption kinetics. This analysis yields activation energies of 0.90±0.10, 0.70±0.07, and 0.45±0.05 eV for removal of the hydration water for epsomite, natron, and mirabilite, respectively. A simple extrapolation indicates that at Europa surface temperatures (<130 K), epsomite should remain Hydrated over geologic timescales (∼1011–1014 years), whereas natron and mirabilite may dehydrate appreciably in approximately 108 and 103 years, respectively. A small amount of SO2 was detected during and after 100 eV electron-beam irradiation of deHydrated epsomite and mirabilite samples, whereas products such as O2 remained below detection limits. The upper limit for the 100 eV electron-induced damage cross section of mirabilite and epsomite is ∼10−19 cm2. The overall radiolytic stability of these minerals is partially due to (1) the multiply charged nature of the sulfate anion, (2) the low probability of reversing the attractive Madelung (mostly the attractive electrostatic) potential via Auger decay, and (3) solid-state caging effects. Our laboratory results on the thermal and radiolytic stabilities of these Salt minerals indicate that Hydrated magnesium sulfate and perhaps other Salts could exist for geologic timescales on the surface of Europa.
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Thermal and radiation stability of the Hydrated Salt minerals epsomite, mirabilite, and natron under Europa environmental conditions
Journal of Geophysical Research: Planets, 2001Co-Authors: Thomas B. Mccord, Thomas M. Orlando, Glenn Teeter, Gary B. Hansen, M. T. Sieger, Nikolay G. Petrik, Lisa Van KeulenAbstract:We report studies on the thermal and radiolytic stability of the Hydrated Salt minerals epsomite (MgSO4·7H2O), mirabilite (Na2SO4·10H2O), and natron (Na2CO3·10H2O) under the low-temperature and ultrahigh vacuum conditions characteristic of the surface of the Galilean satellite Europa. We prepared samples, ran temperature-programmed dehydration (TPD) profiles and irradiated the samples with electrons. The TPD profiles are fit using Arrhenius-type first-order desorption kinetics. This analysis yields activation energies of 0.90±0.10, 0.70±0.07, and 0.45±0.05 eV for removal of the hydration water for epsomite, natron, and mirabilite, respectively. A simple extrapolation indicates that at Europa surface temperatures (
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Hydrated Salt minerals on europa s surface from the galileo near infrared mapping spectrometer nims investigation
Journal of Geophysical Research, 1999Co-Authors: Thomas B. Mccord, Dennis L. Matson, Torrence V. Johnson, J. K. Crowley, Fraser P. Fanale, Robert W. Carlson, William D. Smythe, Patrick D. Martin, G B Hansen, Charles A. HibbittsAbstract:We reported evidence of heavily Hydrated Salt minerals present over large areas of Europa's surface from analysis of reflectance spectra returned by the Galileo mission near infrared mapping spectrometer (NIMS) [McCord et al., 1997a, b, 1998a, b]. Here we elaborate on this earlier evidence, present spatial distributions of these minerals, examine alternate water-ice interpretations, expand on our Hydrated-Salts interpretation, consider Salt mineral stability on Europa, and discuss the implications. Extensive well-defined areas on Europa show distinct, asymmetric water-related absorption bands in the 1 to 2.5-μm region. Radiative transfer modeling of water ice involving different particle sizes and layers at Europa temperatures does not reproduce the distinctive Europa water bands. However, ice near its melting temperature, such as in terrestrial environments, does have some characteristics of the Europa spectrum. Alternatively, some classes of heavily Hydrated minerals do exhibit such water bands. Among plausible materials, heavily Hydrated Salt minerals, such as magnesium and sodium sulfates, sodium carbonate and their mixtures, are preferred. All Europa spectral features are present in some Salt minerals and a very good match to the Europa spectrum can be achieved by mixing several Salt spectra. However, no single or mix of Salt mineral spectra from the limited library available has so far been found to perfectly match the Europa spectrum in every detail. The material is concentrated at the lineaments and in chaotic terrain, which are technically disrupted areas on the trailing side. Since the spectrum of the material on Europa is nearly the same everywhere so-far studied, the Salt or Salt-mixture composition may be nearly uniform. This suggests similar sources and processes over at least a near-hemispheric scale. This would suggest that an extensive subsurface ocean containing dissolved Salts is the source, and several possible mechanisms for deposit emplacement are considered. The hydrogen bonds associated with hydration of these Salts are similar or greater in strength and energy to those in pure water ice. Thus, once on the surface, the Salt minerals should be as stable to disruption as water ice at the Europa temperatures, and mechanisms are suggested to enhance the stability of both materials. Spectra obtained of MgSO4·6H2O at 77 K show only small differences from room temperature spectra. The main difference is the appearance of the individual absorptions composing the broad, composite water features and associated with the several different H2O sites in the Salt hydrate molecule. This suggests that the Europa absorption bands are also composites. Thus higher spectral resolution may reveal these diagnostic features in Europa's spectrum. The specific Salts present and their relative abundances would be indicators of the chemistry and conditions of an ocean environment, and areas of fresh, heavy concentration of these minerals should make ideal lander mission sampling sites.
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Hydrated Salt minerals on Europa's surface from the Galileo near‐infrared mapping spectrometer (NIMS) investigation
Journal of Geophysical Research: Planets, 1999Co-Authors: Thomas B. Mccord, Gary B. Hansen, Dennis L. Matson, Torrence V. Johnson, J. K. Crowley, Fraser P. Fanale, Robert W. Carlson, William D. Smythe, Patrick D. Martin, Charles A. HibbittsAbstract:We reported evidence of heavily Hydrated Salt minerals present over large areas of Europa's surface from analysis of reflectance spectra returned by the Galileo mission near infrared mapping spectrometer (NIMS) [McCord et al., 1997a, b, 1998a, b]. Here we elaborate on this earlier evidence, present spatial distributions of these minerals, examine alternate water-ice interpretations, expand on our Hydrated-Salts interpretation, consider Salt mineral stability on Europa, and discuss the implications. Extensive well-defined areas on Europa show distinct, asymmetric water-related absorption bands in the 1 to 2.5-μm region. Radiative transfer modeling of water ice involving different particle sizes and layers at Europa temperatures does not reproduce the distinctive Europa water bands. However, ice near its melting temperature, such as in terrestrial environments, does have some characteristics of the Europa spectrum. Alternatively, some classes of heavily Hydrated minerals do exhibit such water bands. Among plausible materials, heavily Hydrated Salt minerals, such as magnesium and sodium sulfates, sodium carbonate and their mixtures, are preferred. All Europa spectral features are present in some Salt minerals and a very good match to the Europa spectrum can be achieved by mixing several Salt spectra. However, no single or mix of Salt mineral spectra from the limited library available has so far been found to perfectly match the Europa spectrum in every detail. The material is concentrated at the lineaments and in chaotic terrain, which are technically disrupted areas on the trailing side. Since the spectrum of the material on Europa is nearly the same everywhere so-far studied, the Salt or Salt-mixture composition may be nearly uniform. This suggests similar sources and processes over at least a near-hemispheric scale. This would suggest that an extensive subsurface ocean containing dissolved Salts is the source, and several possible mechanisms for deposit emplacement are considered. The hydrogen bonds associated with hydration of these Salts are similar or greater in strength and energy to those in pure water ice. Thus, once on the surface, the Salt minerals should be as stable to disruption as water ice at the Europa temperatures, and mechanisms are suggested to enhance the stability of both materials. Spectra obtained of MgSO4·6H2O at 77 K show only small differences from room temperature spectra. The main difference is the appearance of the individual absorptions composing the broad, composite water features and associated with the several different H2O sites in the Salt hydrate molecule. This suggests that the Europa absorption bands are also composites. Thus higher spectral resolution may reveal these diagnostic features in Europa's spectrum. The specific Salts present and their relative abundances would be indicators of the chemistry and conditions of an ocean environment, and areas of fresh, heavy concentration of these minerals should make ideal lander mission sampling sites.
Pierre Neveu - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of an innovative thermochemical process operating with a hydrate Salt and moist air for thermal storage of solar energy global performance
Applied Energy, 2014Co-Authors: Benoit Y Michel, Nathalie Mazet, Pierre NeveuAbstract:This paper investigates an innovative open thermochemical system dedicated to high density and long term (seasonal) storage purposes. It involves a hydrate/water reactive pair and operates with moist air. This work focuses on the design of and experimentation with a large scale prototype using SrBr2/H2O as a reactive pair (400kg of Hydrated Salt, 105kWh of storage capacity and a reactor energy density of 203kWh/m3). Promising conclusions have been obtained regarding the feasibility and performance of such a storage process. Hydration specific powers from 0.75 to 2W/kg have been reached for a bed Salt energy density of 388kWh/m3. Moreover, two important parameters that control the storage system have been identified and investigated: the equilibrium drop and the mass flow rate of moist air. Both have a strong influence on the reaction kinetics and therefore on the reactor’s thermal power.
Charles A. Hibbitts - One of the best experts on this subject based on the ideXlab platform.
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Hydrated Salt Minerals on Ganymede's Surface: Evidence of an Ocean Below
Science (New York N.Y.), 2001Co-Authors: Thomas B. Mccord, Gary B. Hansen, Charles A. HibbittsAbstract:Reflectance spectra from Galileo's near-infrared mapping spectrometer (NIMS) suggests that the surface of Ganymede, the largest satellite of Jupiter, contains Hydrated materials. These materials are interpreted to be similar to those found on Europa, that is, mostly frozen magnesium sulfate brines that are derived from a subsurface briny layer of fluid.
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Hydrated Salt minerals on europa s surface from the galileo near infrared mapping spectrometer nims investigation
Journal of Geophysical Research, 1999Co-Authors: Thomas B. Mccord, Dennis L. Matson, Torrence V. Johnson, J. K. Crowley, Fraser P. Fanale, Robert W. Carlson, William D. Smythe, Patrick D. Martin, G B Hansen, Charles A. HibbittsAbstract:We reported evidence of heavily Hydrated Salt minerals present over large areas of Europa's surface from analysis of reflectance spectra returned by the Galileo mission near infrared mapping spectrometer (NIMS) [McCord et al., 1997a, b, 1998a, b]. Here we elaborate on this earlier evidence, present spatial distributions of these minerals, examine alternate water-ice interpretations, expand on our Hydrated-Salts interpretation, consider Salt mineral stability on Europa, and discuss the implications. Extensive well-defined areas on Europa show distinct, asymmetric water-related absorption bands in the 1 to 2.5-μm region. Radiative transfer modeling of water ice involving different particle sizes and layers at Europa temperatures does not reproduce the distinctive Europa water bands. However, ice near its melting temperature, such as in terrestrial environments, does have some characteristics of the Europa spectrum. Alternatively, some classes of heavily Hydrated minerals do exhibit such water bands. Among plausible materials, heavily Hydrated Salt minerals, such as magnesium and sodium sulfates, sodium carbonate and their mixtures, are preferred. All Europa spectral features are present in some Salt minerals and a very good match to the Europa spectrum can be achieved by mixing several Salt spectra. However, no single or mix of Salt mineral spectra from the limited library available has so far been found to perfectly match the Europa spectrum in every detail. The material is concentrated at the lineaments and in chaotic terrain, which are technically disrupted areas on the trailing side. Since the spectrum of the material on Europa is nearly the same everywhere so-far studied, the Salt or Salt-mixture composition may be nearly uniform. This suggests similar sources and processes over at least a near-hemispheric scale. This would suggest that an extensive subsurface ocean containing dissolved Salts is the source, and several possible mechanisms for deposit emplacement are considered. The hydrogen bonds associated with hydration of these Salts are similar or greater in strength and energy to those in pure water ice. Thus, once on the surface, the Salt minerals should be as stable to disruption as water ice at the Europa temperatures, and mechanisms are suggested to enhance the stability of both materials. Spectra obtained of MgSO4·6H2O at 77 K show only small differences from room temperature spectra. The main difference is the appearance of the individual absorptions composing the broad, composite water features and associated with the several different H2O sites in the Salt hydrate molecule. This suggests that the Europa absorption bands are also composites. Thus higher spectral resolution may reveal these diagnostic features in Europa's spectrum. The specific Salts present and their relative abundances would be indicators of the chemistry and conditions of an ocean environment, and areas of fresh, heavy concentration of these minerals should make ideal lander mission sampling sites.
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Hydrated Salt minerals on Europa's surface from the Galileo near‐infrared mapping spectrometer (NIMS) investigation
Journal of Geophysical Research: Planets, 1999Co-Authors: Thomas B. Mccord, Gary B. Hansen, Dennis L. Matson, Torrence V. Johnson, J. K. Crowley, Fraser P. Fanale, Robert W. Carlson, William D. Smythe, Patrick D. Martin, Charles A. HibbittsAbstract:We reported evidence of heavily Hydrated Salt minerals present over large areas of Europa's surface from analysis of reflectance spectra returned by the Galileo mission near infrared mapping spectrometer (NIMS) [McCord et al., 1997a, b, 1998a, b]. Here we elaborate on this earlier evidence, present spatial distributions of these minerals, examine alternate water-ice interpretations, expand on our Hydrated-Salts interpretation, consider Salt mineral stability on Europa, and discuss the implications. Extensive well-defined areas on Europa show distinct, asymmetric water-related absorption bands in the 1 to 2.5-μm region. Radiative transfer modeling of water ice involving different particle sizes and layers at Europa temperatures does not reproduce the distinctive Europa water bands. However, ice near its melting temperature, such as in terrestrial environments, does have some characteristics of the Europa spectrum. Alternatively, some classes of heavily Hydrated minerals do exhibit such water bands. Among plausible materials, heavily Hydrated Salt minerals, such as magnesium and sodium sulfates, sodium carbonate and their mixtures, are preferred. All Europa spectral features are present in some Salt minerals and a very good match to the Europa spectrum can be achieved by mixing several Salt spectra. However, no single or mix of Salt mineral spectra from the limited library available has so far been found to perfectly match the Europa spectrum in every detail. The material is concentrated at the lineaments and in chaotic terrain, which are technically disrupted areas on the trailing side. Since the spectrum of the material on Europa is nearly the same everywhere so-far studied, the Salt or Salt-mixture composition may be nearly uniform. This suggests similar sources and processes over at least a near-hemispheric scale. This would suggest that an extensive subsurface ocean containing dissolved Salts is the source, and several possible mechanisms for deposit emplacement are considered. The hydrogen bonds associated with hydration of these Salts are similar or greater in strength and energy to those in pure water ice. Thus, once on the surface, the Salt minerals should be as stable to disruption as water ice at the Europa temperatures, and mechanisms are suggested to enhance the stability of both materials. Spectra obtained of MgSO4·6H2O at 77 K show only small differences from room temperature spectra. The main difference is the appearance of the individual absorptions composing the broad, composite water features and associated with the several different H2O sites in the Salt hydrate molecule. This suggests that the Europa absorption bands are also composites. Thus higher spectral resolution may reveal these diagnostic features in Europa's spectrum. The specific Salts present and their relative abundances would be indicators of the chemistry and conditions of an ocean environment, and areas of fresh, heavy concentration of these minerals should make ideal lander mission sampling sites.
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Properties of Hydrated Salts Including Under Europa Conditions
1999Co-Authors: Thomas B. Mccord, Thomas M. Orlando, Gary B. Hansen, M. T. Sieger, J. K. Crowley, Charles A. Hibbitts, L. M. Van KeulenAbstract:Introduction: Hydrated Salt minerals were predicted to exist on Europa from models of its thermodynamic evolution [1, 2]. Recent reflectance spectroscopic observations by the Galileo NIMS investigation have revealed evidence of their existence in the surface material in well-defined areas [3, 4]. Interpretation of the NIMS spectra, however, has been hindered by the paucity of laboratory data for this class of minerals, particularly under the temperature and pressure conditions and the radiation environment of Europa’s surface. Thus, we have begun an effort to determine the properties and behavior of Hydrated Salt minerals including under Europan conditions. Of particular interest are the VIS-IR spectral properties because the evidence for the existence of these minerals is based on reflectance spectra in the 0.7 to 5.2 μm spectral region.
K. Ismail - One of the best experts on this subject based on the ideXlab platform.
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electrical conductance of sodium dodecyl sulfate in calcium nitrate tetrahydrate acetamide melts
Journal of Chemical & Engineering Data, 2001Co-Authors: Dev S And, K. IsmailAbstract:The specific conductance of sodium dodecyl sulfate (SDS) in molten mixtures of calcium nitrate tetrahydrate (CNTH) and acetamide was measured at 38 °C. In these molten mixtures SDS undergoes micellization and the values of the critical micelle concentration (cmc) were estimated. The shape of the specific conductance versus concentration of SDS isotherm depends on the relative amounts of the Hydrated Salt and acetamide present in the molten mixture. The slope of this isotherm is positive in the acetamide-rich (>∼73 mass % acetamide) melt, and it changes to a negative value in the Hydrated Salt-rich melt.
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Electrical Conductance of Sodium Dodecyl Sulfate in Calcium Nitrate Tetrahydrate + Acetamide Melts
Journal of Chemical & Engineering Data, 2001Co-Authors: S. Dev And, K. IsmailAbstract:The specific conductance of sodium dodecyl sulfate (SDS) in molten mixtures of calcium nitrate tetrahydrate (CNTH) and acetamide was measured at 38 °C. In these molten mixtures SDS undergoes micellization and the values of the critical micelle concentration (cmc) were estimated. The shape of the specific conductance versus concentration of SDS isotherm depends on the relative amounts of the Hydrated Salt and acetamide present in the molten mixture. The slope of this isotherm is positive in the acetamide-rich (>∼73 mass % acetamide) melt, and it changes to a negative value in the Hydrated Salt-rich melt.
Sergio Salviati - One of the best experts on this subject based on the ideXlab platform.
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ice templated nanocellulose porous structure enhances thermochemical storage kinetics in Hydrated Salt graphite composites
Renewable Energy, 2020Co-Authors: Sergio Salviati, Federico Carosio, Guido Saracco, Francesco Cantamessa, Lilian Medina, Lars Berglund, Alberto FinaAbstract:Abstract The freeze-drying technique is employed for the production of novel strontium bromide/graphite/nanocellulose composites for thermochemical heat storage application. The aim is to obtain a better control and stability of Salt organization within the composite, while maximizing the air/Salt and Salt/graphite interfacial areas and enhancing mass and heat transfer associated to the Salt hydration and dehydration. A comparison with a conventional wet impregnation method is also reported. The morphology was investigated by means of scanning electron microscopy. Differential scanning calorimetry was employed to evaluate the energy storage density, while hydration kinetics were evaluated at 23 °C and 50% RH. The wet impregnation approach delivered materials with a limited porosity while freeze-drying produced highly porous structures with oriented channels for moisture transport across the composite. The organic binder provided an active contribution to the energy storage process, producing energy storage densities up to 764 kJ/kg, 48% greater than the theoretical value. Freeze-dried nanocellulose composites evidenced a significant increase of 54% in the hydration kinetics, compared to the pristine Salt. Based on these results, the freeze-drying of ternary composites based on Salt hydrate, graphite and nanocellulose is envisaged as a promising route for the production of fast charge and discharge thermochemical storage systems.
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Hydrated Salt graphite polyelectrolyte organic inorganic hybrids for efficient thermochemical storage
Nanomaterials, 2019Co-Authors: Sergio Salviati, Federico Carosio, Guido Saracco, Alberto FinaAbstract:Hydrated Salt thermochemical energy storage (TES) is a promising technology for high density energy storage, in principle opening the way for applications in seasonal storage. However, severe limitations are affecting large scale applications, related to their poor thermal and mechanical stability on hydration/dehydration cycling. In this paper, we report the preparation and characterization of composite materials manufactured with a wet impregnation method using strontium bromide hexahydrate (SBH) as a thermochemical storage material, combined with expanded natural graphite (G). In addition to these fully inorganic formulations, an organic polyelectrolyte (PDAC, polydiallyldimethylammonium chloride) was exploited in the structure, with the aim to stabilize the Salt, while contributing to the sorption/desorption process. Different formulations were prepared with varying PDAC concentration to study its contribution to material morphology, by electron microscopy and X-ray diffraction, as well as water sorption/desorption properties, by thermogravimetry and differential calorimetry. Furthermore, the SBH/G/PDAC powder mixture was pressed to form tabs that were analyzed in a climatic chamber, which is evidence for an active role of PDAC in the improvement of water sorption, coupled with a significant enhancement of mechanical resistance upon hydration/dehydration cycling. Therefore, the addition of the polyelectrolyte is proposed as an innovative approach in the fabrication of efficient and durable TES devices.
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Hydrated Salt/Graphite/Polyelectrolyte Organic-Inorganic Hybrids for Efficient Thermochemical Storage
MDPI AG, 2019Co-Authors: Sergio Salviati, Federico Carosio, Guido Saracco, Alberto FinaAbstract:Hydrated Salt thermochemical energy storage (TES) is a promising technology for high density energy storage, in principle opening the way for applications in seasonal storage. However, severe limitations are affecting large scale applications, related to their poor thermal and mechanical stability on hydration/dehydration cycling. In this paper, we report the preparation and characterization of composite materials manufactured with a wet impregnation method using strontium bromide hexahydrate (SBH) as a thermochemical storage material, combined with expanded natural graphite (G). In addition to these fully inorganic formulations, an organic polyelectrolyte (PDAC, polydiallyldimethylammonium chloride) was exploited in the structure, with the aim to stabilize the Salt, while contributing to the sorption/desorption process. Different formulations were prepared with varying PDAC concentration to study its contribution to material morphology, by electron microscopy and X-ray diffraction, as well as water sorption/desorption properties, by thermogravimetry and differential calorimetry. Furthermore, the SBH/G/PDAC powder mixture was pressed to form tabs that were analyzed in a climatic chamber, which is evidence for an active role of PDAC in the improvement of water sorption, coupled with a significant enhancement of mechanical resistance upon hydration/dehydration cycling. Therefore, the addition of the polyelectrolyte is proposed as an innovative approach in the fabrication of efficient and durable TES devices
