The Experts below are selected from a list of 17886 Experts worldwide ranked by ideXlab platform
Yukitaka Kato - One of the best experts on this subject based on the ideXlab platform.
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dehydration kinetic study of a chemical heat storage material with lithium bromide for a Magnesium Oxide water chemical heat pump
Progress in Nuclear Energy, 2015Co-Authors: Odtsetseg Myagmarjav, Junichi Ryu, Yukitaka KatoAbstract:Abstract The reaction performance of a novel chemical heat storage composite as thermal energy storage medium were evaluated for use in a Magnesium Oxide/water chemical heat pump. The composite, called EML, is composed of pure Mg(OH)2 powder and support materials, including LiBr and expanded graphite to improve reactivity and heat transfer, respectively. The heat storage and heat output capacities of the EML composites were evaluated based on laboratory experiments of dehydration and hydration processes for various molar mixing ratios α of LiBr to Mg(OH)2 using the thermogravimetric method. The heat storage and heat output capacity of the EML composites increased with increasing α. The EML composite with α = 0.100 was estimated to be able to store 1.3 times the heat stored in pure Mg(OH)2 powder after 30 min. Based on these evaluations, the EML composites exhibited sufficient heat storage, heat output capacity, and good mold-ability for practical use in a heat exchange reactor. The EML composite was accordingly confirmed as a candidate material for use in chemical heat pumps. Thus, potential use of the EML composite in a Magnesium Oxide/water chemical heat pump coupled with a small nuclear reactor for district heating systems was evaluated based on the experimental results.
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durable reaction material development for Magnesium Oxide water chemical heat pump
Journal of Chemical Engineering of Japan, 2007Co-Authors: Yukitaka Kato, Tomofumi Saito, Tsutomu Soga, Junichi Ryu, Yoshio YoshizawaAbstract:Durable reaction material for repetitive reaction operation of a chemical heat pump that used a reversible Magnesium Oxide/water reaction system was discussed to enhance the heat pump performance. Because a material for the heat pump use was required to fit multi-production process, a molding method was introduced for material preparation. Some molded samples under different preparation conditions were evaluated kinetically by a thermo-balance analysis. Magnesium hydrOxide prepared from ultra fine particle Magnesium Oxide and purified water showed enough reactivity, and also stable durability to 70 of repetitive reaction cycles. Removal of impurity was effective for durability enhancement of Magnesium hydrOxide made from seawater precipitated precursor. The cost of the precipitated hydrOxide was less than one several tenths of the ultra fine particle material. It was demonstrated that the molded reactant made from precipitated hydrOxide was applicable for multi production and cost reduction of Magnesium hydrOxide material for the heat pump. The thermal performance of Magnesium Oxide/water chemical heat pump was evaluated from experimental results.
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study of chemical heat pump with reaction system of Magnesium Oxide water activation of Magnesium Oxide hydration
Kagaku Kogaku Ronbunshu, 1993Co-Authors: Yukitaka Kato, Norimichi Yamashita, Yoshio YoshizawaAbstract:A chemical heat pump using the reaction system of Magnesium Oxide/water was studied as a thermal storage system by kinetic analysis. This heat pump has been rarely studied because of the low activity of MgO hydration. Therefore, an experimental analysis for activation of MgO hydration was carried out. The result shows that the activity of MgO dehydrated at low temperature (below 623K) is several times higher than that of commercial MgO. The possibility was shown that the reaction system of MgO/H2O is applicable, and the working range of such chemical heat pumps was shown.
Francisco Navarrete - One of the best experts on this subject based on the ideXlab platform.
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enhanced extreme ultraviolet high harmonic generation from chromium doped Magnesium Oxide
Applied Physics Letters, 2021Co-Authors: Viktoria Nefedova, Sven Frohlich, Nicolas Tancognedejean, Francisco Navarrete, Dominik Franz, D Gauthier, A Hamdou, Shatha Kaassamani, Rana NicolasAbstract:High-order harmonic generation (HHG) from crystals is emerging as a new ultrashort source of coherent extreme ultraviolet (XUV) light. Doping the crystal structure can offer a new way to control the source properties. Here, we present a study of HHG enhancement in the XUV spectral region from an ionic crystal, using dopant-induced vacancy defects, driven by a laser centered at a wavelength of 1.55 μm. Our numerical simulations based on solutions of the semiconductor Bloch equations and density-functional theory are supported by our experimental observations and demonstrate an increase in the XUV high harmonic yield from doped bulk Magnesium Oxide (MgO) compared to undoped MgO, even at a low defect concentration. The anisotropy of the harmonic emission as a function of the laser polarization shows that the pristine crystal's symmetry is preserved. Our study paves the way toward the control of HHG in solids with complex defects caused by transition-metal doping.
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enhanced high harmonic generation from chromium doped Magnesium Oxide
High-brightness Sources and Light-driven Interactions Congress 2020 (HILAS MICS EUVXRAY) (2020) paper EM3A.3, 2020Co-Authors: Viktoria Nefedova, Sven Frohlich, Nicolas Tancognedejean, W Boutu, Francisco Navarrete, M F Ciappina, Dominik Franz, D Gauthier, A Hamdou, Shatha KaassamaniAbstract:We report on the enhancement of the high harmonic generation (HHG) in doped Magnesium Oxide with dopant-induced vacancies compared to the undoped crystal. This opens new perspectives towards the control of the attosecond emission during HHG.
Viktoria Nefedova - One of the best experts on this subject based on the ideXlab platform.
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enhanced extreme ultraviolet high harmonic generation from chromium doped Magnesium Oxide
Applied Physics Letters, 2021Co-Authors: Viktoria Nefedova, Sven Frohlich, Nicolas Tancognedejean, Francisco Navarrete, Dominik Franz, D Gauthier, A Hamdou, Shatha Kaassamani, Rana NicolasAbstract:High-order harmonic generation (HHG) from crystals is emerging as a new ultrashort source of coherent extreme ultraviolet (XUV) light. Doping the crystal structure can offer a new way to control the source properties. Here, we present a study of HHG enhancement in the XUV spectral region from an ionic crystal, using dopant-induced vacancy defects, driven by a laser centered at a wavelength of 1.55 μm. Our numerical simulations based on solutions of the semiconductor Bloch equations and density-functional theory are supported by our experimental observations and demonstrate an increase in the XUV high harmonic yield from doped bulk Magnesium Oxide (MgO) compared to undoped MgO, even at a low defect concentration. The anisotropy of the harmonic emission as a function of the laser polarization shows that the pristine crystal's symmetry is preserved. Our study paves the way toward the control of HHG in solids with complex defects caused by transition-metal doping.
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enhanced high harmonic generation from chromium doped Magnesium Oxide
High-brightness Sources and Light-driven Interactions Congress 2020 (HILAS MICS EUVXRAY) (2020) paper EM3A.3, 2020Co-Authors: Viktoria Nefedova, Sven Frohlich, Nicolas Tancognedejean, W Boutu, Francisco Navarrete, M F Ciappina, Dominik Franz, D Gauthier, A Hamdou, Shatha KaassamaniAbstract:We report on the enhancement of the high harmonic generation (HHG) in doped Magnesium Oxide with dopant-induced vacancies compared to the undoped crystal. This opens new perspectives towards the control of the attosecond emission during HHG.
Rana Nicolas - One of the best experts on this subject based on the ideXlab platform.
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enhanced extreme ultraviolet high harmonic generation from chromium doped Magnesium Oxide
Applied Physics Letters, 2021Co-Authors: Viktoria Nefedova, Sven Frohlich, Nicolas Tancognedejean, Francisco Navarrete, Dominik Franz, D Gauthier, A Hamdou, Shatha Kaassamani, Rana NicolasAbstract:High-order harmonic generation (HHG) from crystals is emerging as a new ultrashort source of coherent extreme ultraviolet (XUV) light. Doping the crystal structure can offer a new way to control the source properties. Here, we present a study of HHG enhancement in the XUV spectral region from an ionic crystal, using dopant-induced vacancy defects, driven by a laser centered at a wavelength of 1.55 μm. Our numerical simulations based on solutions of the semiconductor Bloch equations and density-functional theory are supported by our experimental observations and demonstrate an increase in the XUV high harmonic yield from doped bulk Magnesium Oxide (MgO) compared to undoped MgO, even at a low defect concentration. The anisotropy of the harmonic emission as a function of the laser polarization shows that the pristine crystal's symmetry is preserved. Our study paves the way toward the control of HHG in solids with complex defects caused by transition-metal doping.
Lakshmi M Kantam - One of the best experts on this subject based on the ideXlab platform.
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nanocrystalline Magnesium Oxide stabilized gold nanoparticles an advanced nanotechnology based recyclable heterogeneous catalyst platform for the one pot synthesis of propargylamines
Green Chemistry, 2011Co-Authors: Keya Layek, Lakshmi M Kantam, Rajashree Chakravarti, H Maheswaran, Ajayan VinuAbstract:A simple and elegant synthesis of gold nanoparticlesvia counter ion stabilization of AuCl4− on nanocrystalline Magnesium Oxide support followed by sodium borohydride reduction is described here. A thorough characterization of the resulting heterogeneous material revealed the presence of uniformly distributed gold nanoparticles (10–12 nm) deposited on to (111) plane of quasi-crystalline icosahedral lattice of nanocrystalline Magnesium Oxide which exhibits excellent catalytic activity for the one pot synthesis of structurally divergent propargylamines via a three component coupling of an alkyne, an amine and an aldehyde without requiring any additives or inert atmosphere. The catalyst contains ultra low loading of gold (0.236 mol%), and turnover numbers as high as 400 are obtained. The catalyst can be isolated by simple centrifugation and reused for four cycles.
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nanocrystalline Magnesium Oxide stabilized molybdenum an efficient heterogeneous catalyst for the aerobic oxidation of alcohols to carbonyl compounds
Advanced Synthesis & Catalysis, 2008Co-Authors: Lakshmi M Kantam, B Sreedhar, Jagjit Yadav, Soumi Laha, Suresh K BhargavaAbstract:A nanocrystalline Magnesium Oxide-stabilized molybdenum(VI) complex catalyzed the oxidation of primary and secondary alcohols to carbonyl compounds in excellent yields using molecular oxygen as stoichiometric oxidant. The nanomaterials with their three-dimensional structure and defined size and shape act as suitable supports for metal complexes. The catalyst can be reused for four runs without any significant loss of activity.
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transfer hydrogenation of carbonyl compounds catalyzed by ruthenium nanoparticles stabilized on nanocrystalline Magnesium Oxide by ionic liquids
Advanced Synthesis & Catalysis, 2008Co-Authors: Lakshmi M Kantam, B Sreedhar, Sudarshan R Reddy, Ujjwal Pal, Suresh K BhargavaAbstract:Transfer hydrogenation of various carbonyl compounds was achieved in excellent yields by ruthenium nanoparticles stabilized on the nanocrystalline Magnesium Oxide by the incorporation of choline hydrOxide, a basic ionic liquid. The procedure is simple, efficient and the catalyst can be recycled five times.
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nanocrystalline Magnesium Oxide stabilized palladium 0 an efficient and reusable catalyst for selective reduction of nitro compounds
ChemInform, 2008Co-Authors: Lakshmi M Kantam, B Sreedhar, Ujjwal Pal, Rajashree Chakravarti, Suresh K BhargavaAbstract:An efficient, mild and selective synthesis of aromatic and aliphatic amines from the corresponding nitro compounds has been realized by using a ligand-free heterogeneous nanocrystalline Magnesium Oxide-stabilized palladium(0) catalyst, employing molecular hydrogen as the reductant. The catalyst is recovered quantitatively by simple filtration and was reused for several cycles with consistent activity.
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synthesis of α amino nitriles through strecker reaction of aldimines and ketoimines by using nanocrystalline Magnesium Oxide
Tetrahedron, 2008Co-Authors: Lakshmi M Kantam, Koosam Mahendar, B Sreedhar, B M ChoudaryAbstract:Abstract Strecker reactions of various aldimines as well as ketoimines with TMSCN proceeded smoothly under mild conditions to give the corresponding α-amino nitriles and α,α-disubstituted α-amino nitriles, respectively, in good to excellent yields in the presence of nanocrystalline Magnesium Oxide. The reaction proceeds through hypervalent silicate species by coordination to O 2− /O − (Lewis basic site) of nanocrystalline Magnesium Oxide, proved by 29 Si NMR.
