Day 1 :
Osaka University, Suita, Osaka 565-0871, Japan
Time : 9:30AM
Y. Ueda has completed his PhD at the age of 27 years from University of Tokyo and postdoctoral studies from Princeton Plasma Physics Laboratory. He is the professor of Graduate School of Engineering, Osaka University. He has published more than 190 papers in reputed journals and has been serving as an editorial board member of Nuclear Fusion, Journal of Nuclear Materials, and Nuclear Materials and Energy. His major research area is develpment of nuclear fusion energy and he is currently involved in plasma-material interactions in fusion energy devices and applications of these knowledges to the other fields.
From material research aspect of fusion energy development, He plasma induced nano-structure (HIN) on tungsten is very interesting and attractive phenomenon, which has not reported in the other fields. Dense nano-fiber (fiber thickness of a few tens of nm) structure grows up to several µm under appropriate ion energy and temperature conditions. Important underlying processes to produce this structure are He aggromeration and nano-scale bubble formation in tungsten (also seen in various metals). Detailed formation mechanism, especially growth mechanism of nano-fibers, however, has not been understood well. Once we understand formation mechanisms in detail and find appropriate control methods of the nano-fiber structure, various applications will emerge such as catalyst and sensors due to mainly large surface area of the structure.
In this presenataion, systematic experimental results of nano-fiber formation on various transition metals (Hf, Ta, W, Re, Ir, Pt, Au, Nb, Mo) are shown, indicating relations between nano-fiber charactreristics and material properties. The most critical experimental parameter is temperature. Around 30% of melting temperature in K, nano-fiber structure grows fastest for most of metals. But there are some exceptions such as Ta and Nb, in which thick nano-fiber layers are hardly produced, while relatively large surface holes with diameter of sub µm appear. There are some correlations of growth rates of nano-fibers with mechanical properties of metals as well as aggromeration energy of He atoms calculated by a DFT calculation. Some applications of nano-fiber structure will be briefly touched.
Boston University, Boston MA 02215 USA
Time : 10:00AM
Prof. Yang received her doctoral degree in Chemistry from Harvard in 2006. She worked as an associate in McKinsey & Co from 2006 to 2007. Prof. Yang joined Department of Chemistry and Department of Physics and Astronomy at Purdue University in August, 2007 and moved to Boston University Department of Electrical and Computer Engineering and Department of Chemistry in 2017. Prof. Yang’s research interest is focusing on nanomaterials for their potential applications in nanoscale devices, biological and energy applications. She has won the NSF Career Award (2009-2014), Purdue Seed of Success Award and Purdue Outstanding Adviser Award. She served as a guest editor for Journal of Electronic Materials and currently serve on Editorial Board of Scientific Reports.
Disruption of nerve connections between the brain and the rest of the body caused by spinal cord injury could result in paralysis. Recovery is challenging due to failure in spontaneous neural regeneration. None of current clinical treatment targets neural regeneration and only limited functional recovery has been reported. Nanomaterials have been harnessed to promote neuronal growth in vitro. In this work, we present a new nanomaterial scaffold, interfacing and stimulating neural systems mechanically. Specifically, inspired by the hierarchically organized axon bundles in the spinal cord, we developed a “nanoladder” structure composed of a longitudinal micrometer-diameter fiber and multiple nanoscale protrusions to both guide macroscale neural growth and facilitate neurite formation at the subcellular level. Directional and promoted neurite growth is shown on the nanoladder structure. Directional growth and functional connection of organotypic spinal slices are confirmed through fluorescence labeled imaging and electrophysiology measurements on the nanoladder platform. We also demonstrated that such nanoladder concept can be used to further create self-folded 3D scaffolds for in vivo studies and clinical tests.
Sagamihara Surface Lab, Japan.
Project Principal Researcher of Sagamihara Surface Lab, *Professor Emeritus Mie University, *Honorary Professor Southwest Jiaotong University (China), * Representative of MRS-Japan Research Society (Nano Oxides Materials), *Visiting Researcher, University of California-San Diego, USA (1995), *PhD (Kyoto University), MsD (Gifu University).
Engineering plastic films of PET, polyimide and fluorocarbon polymers are used in various applications such as electrical insulation and mechanical materials, utilizing their strong characteristics. Usually adhesives are used to laminate them, causing environmental issues due to organic solvents. The backsheet of solar panels is composed of PVF/PET/PVF. PET is mechanically strong and less-costly but not good for atmospheric tolerance, whereas PVF is excellent for atmospheric tolerance but costly. We developed unique technology of direct bonding of various films by plasma irradiation. Laminates of insulator Aramid/PPS/Aramid are actually used in motors of electric vehicles. Here we report some examples of plasma-bonding technologies and applications.
In plasma irradiation apparatus, the plastic film (PET) is attached on a drum electrode, and gas (O2) is discharged to produce plasma to irradiate the film. The irradiated films are laminated by low heat press (140℃). Bonding strength is measured by 180° peel test. The non-irradiated, irradiated and laminated films are characterized by AFM, XPS, FTIR and GCMM.
XPS results for the non-irradiated and irradiated PET surfaces show a peak at 288.8 eV, attributed to O=C-O- constituting PET molecular structure. This is increased a little due to creation of COOH at the surface by the irradiation. The bottom at 287.6 eV is increased due to forming of C=O bond on the surface, and total oxygen content in the film is increased by the irradiation. The results of GCMM and FTIR indicate that –OH and –COOH are increased on the PET surface by the irradiation. The irradiated PET are bonded tightly by the heat press at above 120°C, bonding strength is larger than 7 N/cm, beyond cohesion failure. All the results strongly suggest that the bonding is associated by chemical bond due to “dehydrated condensation reaction” as well as “hydrogen bond”. Excellent results of direct bonding on various plastic films, long lifetimes of activated surface effects and long-time variations of the bonding strength are also shown.