Netsu Sokutei
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
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Volume 44, Issue 3
Displaying 1-8 of 8 articles from this issue
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Review
  • Measurement Techniques of Thermoelectrics Properties for Nanowire
    Yasuhiro Hasegawa, Mioko Otsuka, Taichi Arisaka
    2017 Volume 44 Issue 3 Pages 77-84
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_77
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    We have developed measurement techniques of thermoelectric properties for Bi nanowire encased in quartz based on the measurement for bulk thermoelectric materials. Though internal impedance of the nanowire would be increased due to its narrower wire diameter, 4-wire probe measurement has been required to obtain the proper evaluation. Therefore, nano-fabrication techniques using dual focused-ion-beam apparatus have also developed to make suitable electrical contact on the side of the nanowire locally. As a result, we are able to introduce 4-wire probe measurement for the nanowire to estimate the physical properties in generalized Ohm's law even if internal impedance of the nanowire is large.
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  • Phase Equilibria of Ionic Liquid + Gas Systems and Their Utilizations
    Takashi Makino, Yuki Kohno, Mitsuhiro Kanakubo
    2017 Volume 44 Issue 3 Pages 85-92
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_85
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    The aim of this review is to provide some information on the gas absorption characters of ionic liquids and the chemical processes utilizing ionic liquid + gas systems. Ionic liquids are salts with the melting points being at or below ambient temperatures. They are unique solvents, of which the characteristics are non-volatile, non-flammable, electrically conductive, miscible with various chemicals, and so on. One of the promising utilizations of ionic liquids is gas absorption media. In order to use the ionic liquids for the chemical processes involved with gas absorption, the understanding of the gas absorption property and mechanism is of primarily importance. This review presents some fundamental data on the following systems: (1) CO2 physical absorption; (2) CO2 chemical absorption; (3) NH3 absorption; (4) water absorption. First, the two-phase equilibria are shown for some typical ionic liquid + gas systems in each section. Then, the gas absorption mechanisms are discussed on the basis of the thermodynamic and spectroscopic analyses. Finally, the separation, reaction-separation, and/or heat-pump processes using ionic liquid are briefly explained.
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  • Investigation of Giant Lorenz Ratio of Dirac-Fermion Systems by Numerical Calculations
    Harukazu Yoshino
    2017 Volume 44 Issue 3 Pages 93-100
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_93
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    The Lorenz ratios (L = κ/(σT)) of the Dirac-fermion systems were numerically calculated using the Boltzmann transport theory, where κ, σ and ܶT are the thermal conductivity, electrical conductivity and absolute temperature, respectively. The bipolar-diffusion effect, which enhances the electronic thermal conductivity κe in intrinsic semiconductors, was introduced to account for the reported giant L of a Dirac-fermion system, graphene at its neutrality condition. It was found that the calculations qualitatively reproduce the experimentally observed gate-voltage dependence of σ,S and κe by considering the energy dependence of the relaxation time; and the electron- and hole-puddles. The calculated value of L amounts to (2–4)L0, where L0= 2.45 × 10-8 W·Ω·K-2 is Sommerfeld value of Wiedemann–Franz law, while the reported L of graphene reaches about 20L0 at most. The rather large L (=3.7L0) was also observed for another Dirac-fermion system, α-(BEDT-TTF)2I3 (BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene) by measuring simultaneously the change in the σ and κ associated with its charge-ordering transition at about 135 K for a single crystal. Another explanation of the giant L on the basis of quantum hydrodynamics is also introduced briefly, while both the bipolar-diffusion and quantum-hydrodynamic mechanisms are not exclusive to each other.
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  • Thermodynamic Consideration on Cholesterol-Induced Lateral Phase Separation within Lipid Bilayer Membranes
    Nobutake Tamai, Masaki Goto, Hitoshi Matsuki
    2017 Volume 44 Issue 3 Pages 101-107
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_101
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    We have so far studied the effect of cholesterol on the bilayer phase behavior of a homologous series of symmetric linear phosphatidylcholines (CnPCs) with different chain lengths (n = 14–18) by means of high-sensitivity differential scanning calorimetry and fluorescence spectroscopy using 6-propionyl-2-(N,N-dimethylamino)naphthalene (Prodan) as a membrane probe. The temperature–cholesterol composition (Xch) phase diagrams constructed for these binary bilayers indicated several important characteristic of the phase behavior of them. First, the phase diagrams are similar to those for the liquid/solid phase equilibria of general binary mixtures that exhibit incongruent melting behavior, suggesting that cholesterol and CnPC molecules are essentially immiscible within the binary bilayer. Second, a characteristic point like a peritectic point appears on the phase diagram, suggesting that cholesterol has a propensity to form a molecular cluster with its surrounding CnPC molecules. The Xch-dependent phase behavior indicated by the phase diagrams, especially cholesterol-induced lateral phase separation, was successfully explained by introducing the so-called superlattice view. In addition, this view allowed us to consider the relationship between the extent of the cholesterol effect and the hydrocarbon-chain length of the host CnPC molecules.
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  • ITC Analysis of Ligand Binding to Lipocalin-type Prostaglandin D Synthase
    Shigeru Shimamoto, Takahiro Maruno
    2017 Volume 44 Issue 3 Pages 108-116
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_108
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    Isothermal titration calorimetry (ITC) is the only technique whereby complete set of thermodynamic profile for molecular interaction can be determined from a single experiment. Binding thermodynamic parameters (free energy, enthalpy, and entropy) provide fundamental information on the forces driving the formation of the protein-ligand complex. The connection between structural and thermodynamic features of protein-ligand binding, however, is not as simple as expected because of the multifactorial character of the enthalpy and entropy of binding. Here, we review the structural and thermodynamic studies of lipocalin-type prostaglandin D synthase (L-PGDS) as a model of broad-ligand binding properties. Our ITC and NMR analyses of interactions between L-PGDS and hydrophilic ligands, NADs, revealed that negatively charged part of ligands is important for binding to L-PGDS. Moreover, the good correlation was found between the binding free energy and hydrophobic surface area of the ligands (ASAh), indicating that increased affinity is associated with increased ASAh. L-PGDS has a large cavity, which contains distinct and separate hydrophilic and hydrophobic parts. Taken together, it is suggested that positively charged hydrophilic part of L-PGDS cavity is involved in ligand specificity and hydrophobic part contributes to affinity.
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  • Studies on Novel Materials by Complementary Use of Calorimetric and Neutron Scattering Methods
    Osamu Yamamuro
    2017 Volume 44 Issue 3 Pages 117-123
    Published: July 25, 2017
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.44.3_117
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    Neutron scattering is a powerful experimental technique which is comprehensive with calorimetry. For the last 20 years, we have carried out both adiabatic calorimetric and various neutron scattering experiments. In the adiabatic calorimetry, the measurements of heat capacity and enthalpy of absorption have been carried out. In the neutron scattering, powder diffraction, inelastic scattering, and quasielastic scattering techniques have been utilized, each providing structural, excitation and relaxational information. The present article shows several examples of the works on phase transitions of hydrogen-bonded systems, hydrogen absorption and interstitial-sites occupation in palladium nanocrystals, low-energy excitations (boson peaks) in vapor-deposited simple molecular glasses, and diffusion dynamics of imidazolium-based ionic liquids. These examples clearly show the complementarity between the calorimetry and neutron scattering.
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Applied Research of Thermal Analysis
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