A research group consisting of Assistant Professor Shiro Ihara, Associate Professor Hikaru Saito, and Professor Mitsuhiro Murayama from the Institute for Materials Chemistry and Engineering, Mizumo Yoshinaga (Master's Program Graduate, currently at Toppan Printing Co., Ltd.) and Kota Wada (Master's Program Student) from the Graduate School of Interdisciplinary Science and Engineering, Professor Satoshi Hata from the Faculty of Interdisciplinary Science and Engineering, and Yuya Miyazaki from Melvil Corporation developed a TEM sample holder for in-situ heating observation that can be transported to a transmission electron microscope (TEM) without exposure to air, and successfully captured the sintering process of copper nanoparticles with an average particle size of 150 nm in three dimensions.