Keynote Speakers

Prof. Umemura Kazuo

Tokyo University of Science

Speech Title: Micron Size Biodevices Using Natural nanoporous Silica
Abstract:  I will introduce two types of biodevices using frustules. Frustules are nanoporous biosilica which are produced by diatom cells. Diatoms are major photosynthetic planktons that are found in rivers, seas, lakes, and even in hot springs. Sizes of frustules are varied from several microns to several hundred microns, however, sizes and shapes of the frustules obtained in the same culture of isolated diatom cells are uniform because of the regulation with their genomes. Nano and micro pores are found on frustule surfaces; therefore, specific gravity of frustules is lower than other micron size materials such as glass beads. In our experimental data, frustules were not settled permanently without stirring at 37 °C. It could be directly confirmed using a ‘tumbled’ optical microscope. Frustules were gradually settled at room temperature; however, the settlements of frustules were much slower than other related SiO2 micron size materials such as diatomite, mesoporous silica, and glass beads. We attached papain enzymes or DNA-wrapped single-walled carbon nanotubes (SWNTs) on frustule surfaces. In the case of the papain enzyme devices, better enzyme activities were obtained comparing with the use of other SiO2 materials. In the case of SWNT devices, near-infrared photoluminescence (PL) of SWNTs was well appeared even on frustule surfaces. The SWNT device was effective to distinguish biomolecules by the PL change. For example, when papain molecules were injected to the SWNT frustule suspension, PL intensity from SWNTs were significantly increased. Furthermore, the PL change was specific according to chirality of SWNTs. The data revealed a potential of biosensing methods using the SWNT chirality. For the reactions, it was not necessary to external stirring at 37 °C. Nevertheless, the fabricated frustule biodevices could be easily recovered by simple centrifugation after the use. Both papain devices and SWNT devices could be re-used at least five times.      

Biography: Dr. Kazuo Umemura is a full professor of Tokyo University of Science. His specialty is biophysics, especially, nanobioscience and nanobiotechnology. One of his recent interests is nanoscopic research of hybrids of biomolecules and carbon nanotubes (CNTs). Unique structures and physical/chemical properties of the hybrids are promising in biological applications such as nanobiosensors and drug delivery.

Dr. Umemura received his B.S. degree in Physics from Nagoya University. His M.S. and Ph.D. degrees were given from Tokyo Institute of Technology. After working at several institutes/universities as a researcher in Japan and in China, he became a professor of Tokyo University of Science. Kagurazaka campus of Tokyo University of Science is located at the center of Tokyo, so five subway/railway lines reach in front of the campus.

Prof. Jia-Lin Tsai

National Yang Ming Chiao Tung University


Speech Title: Mechanical Properties and Applications of Nanocomposites with Aligned Graphene
Abstract:  This study fabricated nanocomposites with aligned graphene platelets and examined their mechanical properties. Graphene platelets were incorporated into epoxy matrix through mechanical mixing, followed by sonication for homogeneous dispersion. To align the graphene platelets, before curing, an electric field was applied to the epoxy–graphene compound. Real-time microscopic observation revealed that under an electric field, the graphene platelets rotated, translated, and eventually formed a chain-like microstructure along the electric field. Tensile tests were conducted on the nanocomposites with aligned graphene, and failure mechanisms were identified using scanning electrical microscopy of the fracture surfaces. For comparison, nanocomposites with randomly oriented graphene were prepared and then subjected to tensile loading. Moreover, the moduli of the graphene nanocomposites were characterized using Mori–Tanaka micromechanical model. The experimental results indicated that the nanocomposites with aligned graphene exhibited higher tensile moduli and tensile strength than those with randomly oriented graphene.  In addition to the mechanical properties, the electrical conductivity of nanocomposites with different graphene loadings was measured with an electrometer. The results indicated that when the graphene loading was 0.15 wt%, the electrical conductivity of the nanocomposites was close to the percolation threshold. Subsequently, three-point bending tests were conducted on single edge notch bending (SENB) specimens with the graphene aligned perpendicular to the loading direction. During the tests, the electrical resistance of the specimens was measured using a high-resistance meter. The results indicated that the resistance of the samples increased markedly prior to crack extension. Thus, aligned graphene can be employed to detect crack extensions. Moreover, the crack extension in single lap joint was detected using the aligned graphene embedded within the epoxy adhesive. The aligned graphene provides an electrically conductive medium between composite adherents. It was observed that changes in resistance were correlated with the increase in crack length, and this relationship was described using a resistance formula.       

Biography: Dr. Jia-Lin Tsai is a full professor in the Department of Mechanical Engineering at National Yang Ming Chiao Tung University in Taiwan. He completed his MS and PhD degrees at School of Aeronautics and Astronautics, Purdue University in the United States in the years 1998 and 2001, respectively. Following this, he conducted his postdoctoral research at Purdue from 2001 to 2002. His academic journey led him to National Chiao Tung University in Taiwan, where he served as an assistant professor from 2002 to 2006, and subsequently, as an associate professor from 2006 to 2009. In 2009, he achieved the rank of full professor. Dr. Tsai also took on administrative responsibilities as the Chairman of the Department of Mechanical Engineering at National Chiao Tung University from 2014 to 2017. Currently, he holds the position of Associate Editor for the journals "Journal of Mechanics" and "Multi-scale Science and Engineering." His primary research expertise lies in the characterization of mechanical properties of composites and nanocomposites, failure analysis and fracture mechanics. He received best paper awards from Journal of Mechanics at solid mechanics area in the year of 2022.

Speakers in 2024 will be announced soon...