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  • Author or Editor: J. W. Moon x
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Journal of Radioanalytical and Nuclear Chemistry
Authors: M. Ebihara, Y. Chung, H. Dung, J. Moon, B. Ni, T. Otoshi, Y. Oura, F. Santos, F. Sasajima, Sutisna, B. Wee, W. Wimolwattanapun and A. Wood

Abstract  

Air particulate matter (APM) samples (PM2.5 and PM10–2.5) were collected at 13 sampling points in 8 Asian countries and their chemical compositions were determined by using neutron activation analysis (NAA) with the k 0-standardization method in addition to conventional comparative method of NAA. Analytical data showed that mass concentration and elemental composition of the APM collected are variable in terms of time and space, and are related to the characteristics of the sampling sites concerned. NAA was proved to be highly effective for the regional characterization of APM in chemical composition.

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Thermodynamic transition properties of highly ordered smectic phases

Series of main-chain liquid crystalline polyethers

Journal of Thermal Analysis and Calorimetry
Authors: Y Yoon, R. -M. Ho, F. Li, B. Moon, D. Kim, J. -Y. Park, F. W. Harris, S. Z. D. Cheng, V. Percec and P. Chu

A series of polyethers have been synthesized from 1-(4-hydroxy-4′-biphenyl)-2-(4-hydroxyphenyl)propane and α, Ω-dibromoalkanes having different numbers of methylene units [TPPs]. Both odd- and even-numbered TPPs [TPP(n=odd)s and TPP(n=even)s) exhibit multiple transitions during cooling and heating and they show little supercooling dependence, indicating close-to-equilibrium nature of these transitions. Combining the structural characterization obtainedvia wide angle X-ray diffraction powder and fiber patterns at different temperatures and the morphological observations from microscopy techniques, not only the nematic liquid crystalline phase but also highly ordered smecticF, smectic crystalG andH phases have been identified. The phase diagrams for both TPP(n=odd)s and TPP(n=even)s have been constructed [1–3]. Thermodynamic properties (enthalpy and entropy changes) during these transitions are studied based on differential scanning calorimetry experiments. The contributions of the mesogenic groups and methylene units to each ordering process can be separated and they indicate the characteristics of these processes thereby providing estimations of the transition types.

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