Netsu Sokutei
Online ISSN : 1884-1899
Print ISSN : 0386-2615
ISSN-L : 0386-2615
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Volume 45, Issue 4
Displaying 1-7 of 7 articles from this issue
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Article
  • Stability of Streptococcal Protein G as an Affinity Ligand for Antibody Fragments
    Shinichi Yoshida
    2018 Volume 45 Issue 4 Pages 138-142
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_138
    JOURNAL FREE ACCESS
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    Streptococcal protein G (SpG) is a bacterial surface protein, binding mainly to the Fc (high affinity) and Fab (low affinity) regions of immunoglobulins. The SpG-immobilized affinity chromatography resin is useful for the purification of antibodies. Improvement of the affinity of SpG to Fab enhances its application to the purification of Fab-based antibody fragments. We found four important mutations of SpG, improving its affinity for Fab through affinity maturation using a ribosomal display system. In this article, we discuss the thermodynamic effects of these mutations on the function and stability of SpG as an affinity ligand using calorimetric measurements. Isothermal titration calorimetry analysis elucidated the quantitative enthalpic/entropic contributions of these individual mutations on the interaction of SpG with Fab. In addition, differential scanning calorimetry analysis revealed the destabilizing effects of these mutations on the thermodynamic stability of SpG. These calorimetric analyses may contribute to the current understanding of the mechanism of action of such mutations and further refinement of affinity ligands through protein engineering.
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Special Issue
  • Thermal Analysis of energetic materials －Thermal Decomposition Mechanism of Ammonium Dinitramide－
    Yu-ichiro Izato, Atsumi Miyake
    2018 Volume 45 Issue 4 Pages 143-148
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_143
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    Energetic materials are widely used as propellants, explosives and pyrotechnics. To allow the safe development and effective use of energetic devices, it is important to understand reaction mechanisms and thermal properties of energetic materials. Thermal analysis is a strong tool to investigate reaction of energetic materials. In this paper, reaction scheme and thermal behavior of ammonium dinitramide, which is one of the most promising next generation oxidizer of rocket propellants, are analyzed experimentally and theoretically. DSC, TG-EGA, DSC-Raman studies have been carried out to measure the heat of reaction and decomposition products, and quantum chemistry calculation have revealed possible reaction pathways.
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  • Accidental Explosion of Nitrocellulose and Future Tasks
    Katsumi Katoh
    2018 Volume 45 Issue 4 Pages 149-154
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_149
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    Nitrocellulose (NC), which is a nitrate ester compound having ONO2 group in their chemical structure, is an industrially useful material utilized as a raw material for explosives, lacquers, and celluloid products. However, NC is an unstable material that has a risk of undergoing spontaneous decomposition even at low temperatures. Accumulation of decomposition heat can cause spontaneous ignition, and numerous relevant accidental explosions have been reported. Although the NC spontaneous decomposition has already been investigated for a long time, recent accidental explosions like the catastrophe in China in 2015 have made the relevant studies again draw attention from the viewpoint of the safety aspect. The author's research group has comprehensively investigated the spontaneous decomposition behavior of NC so far, using heat flow calorimetry. In this article, the author introduced a part of our achievement and the future tasks related to the thermal decomposition mechanism, hazard evaluation method, and novel stabilizer of NC.
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  • Thermal Analysis of Explosive Compounds and Reproducible Test on Explosion
    Ken Okada
    2018 Volume 45 Issue 4 Pages 155-160
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_155
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    Two topics of explosive accidents were mentioned in this paper. One is ion exchange resin, the other is silver compounds. An explosion occurred while ion exchange resin (IER) was being used in the analytical pretreatment. To clarify the cause of the accident and go/no-go criteria of the explosion, elemental analysis of the IER, DSC analysis, SIKAREX analysis (a screening tool for runaway reactions), and Raman spectroscopy were performed. Finally, experiments on the same scale as the accident were conducted in an explosion chamber. When HClO4 was added to IER-NO3, the IER violently exploded without any heating nor metal ions such as uranium. It was confirmed that the accident was caused by an incorrect procedure in the chemical process. From the standpoint of explosion safety, IER-NO3 in particular should be kept away from perchloric acid in the laboratory. In the silver mirror reaction using ammoniacal silver solution, silver nitride (Ag3N) is generated, when the solution is allowed to stand. This compound is highly explosive. Thus, for a recycling process of silver compounds from ammoniacal silver solution, it is required to establish safety treatment of the solution. In the present study, various conditions for the safety treatment have been investigated on a laboratory scale. When an aqueous solution of Ag2O/NH3 was allowed to stand in the open air at ambient temperature, Ag3N was finally generated, as expected.
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  • Various Factors Affecting Differential Scanning Calorimetry Evaluations
    Miyako Akiyoshi, Takehiro Matsunaga
    2018 Volume 45 Issue 4 Pages 161-167
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_161
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    As the explosiveness of a chemical substance is correlated with its exothermic decomposition energy, DSC has also been used as a hazard evaluation test. Although DSC provides a safe means of performing hazard evaluation of chemicals, with the convenience of only requiring very small amounts of material, the value obtained is known to be affected by, e.g., the sample vessel material/type, the heating rate, and the sample volume. This work introduces the influences of the type and material of the sample vessel and the amount of sample on the heat behavior by providing some concrete examples. DSC evaluates both the condensed and gas phase reactions in vessels, and the factors described above have a complex effect on these reactions. Furthermore, for substances that can react with metals such as stainless steel, appropriate hazard evaluation methods have not been established. Gold plated vessels are not necessarily inert with respect to their effects on the reactions, and glass vessels have also exhibited problems. The development of pressure-resistant sample vessels made of inert substances is desirable. Careful attention should be paid to factors that could affect results to avoid deriving wrong judgments.
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Review
  • Fundamentals and Applications of Thermally Stimulated Current Measurement
    Yoshinobu Hosoi, Taisei Hirayama
    2018 Volume 45 Issue 4 Pages 168-173
    Published: October 20, 2018
    Released on J-STAGE: November 20, 2022
    DOIhttps://doi.org/10.11311/jscta.45.4_168
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    Thermally stimulated current (TSC) is a short-circuit current which flows due to the displacement of charges in samples during heating. TSC measurement mainly evaluates two thermal relaxation processes: one is dipoles and the other is trapped charges. It is used in a variety of research fields, i.e., electronic devices such as diodes, transistors, and solar cells as well as dielectric, insulator, semiconductor, and ferroelectric materials. In this paper, we describe the fundamental of TSC measurement and the typical three applications. TSC enables us to observe the relaxation processes of molecular motions of plasticized and blended polymers. TSC also plays a crucial role in the evaluation of amount of charges and its stability in polymer electrets. Recently, defects of organic light emitting diodes (OLEDs) have been studied by TSC.
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