To investigate the conformational features of individual organic molecules on the substrates, we synthesized 5-(4-methylthiophenyl)-10, 15, 20-tris(3,5-di-t-butylphenyl) porphyrin (MSTBPP) molecules. The conformation of MSTBPP molecules dispersed on an Au(111) surface was investigated using Frequency Modulation Non-contact Atomic Force Microscopy (FM-NCAFM) under UHV condition with nano-meter spatial resolution. It was found that the methylthiophenyl group of MSTBPP molecules enhances the attractive interaction between the molecule and the substrate, which works as an anchor to fix their relative position to the substrate. This function dominates their conformation and mobility on the substrate. These findings lead to various possible strategies to control the conformation of molecules on the substrate, which is one of the important keys to realize the supra-molecular devices.
We invented a MS microscope for anatomists or cell biologists, because we wish to know what we see. Mass spectrometry has played an important role in the proteomics research in the post-genomic era. Proteomics data obtained by mass spectrometry are now being combined with spatial information, which is called mass imaging. The current mass imaging techniques, however, do not provide molecular identifications. Our instrument, an MS microscope, will provide observation and identification using a tandem mass spectrometer equipped with a new concept mass analyzers. We believe that this instrument will contribute to both biological and medical applications.
We control thermal properties such as thermal radiative properties and thermal conductivity by using bio-inspired nano-structures. It is well known that the colors of Morpho butterfly wings are due to interactions between light waves and periodic structures of sub-micron scale. By incorporating micron periodic structures into other materials, we can control thermal radiative properties. The micro structures are fabricated on a 4-inch silicon wafer by using self-assembly of the colloidal silica particles under the specific condition. The reflectivity of the fabricated samples is determined by using a FT-IR (Fourier Transform-Infrared Spectroscopy). The spectral reflectivity is enhanced at a specific wavenumber. An analogous interaction between waves and nano-structures can be used to control the thermal conductivity of semiconductors and insulators. Nano-structures can reduce the conductivity by impeding the lattice vibrations that carry heat. We conducted phonon transport numerical analysis to study the reduction of thermal conductivity. The results of the numerical analysis show that the thermal conductivity can be reduced to less than 10% of the bulk value by using nano-structures.
A method for reproducible site-specific force spectroscopic measurements at room temperature by combining frequency modulation atomic force microscopy and the atom tracking technique is proposed. The atom tracking enables to compensate the change in the tip-sample relative position due to the thermal drift as well as to precise positioning of the AFM tip over the same spot of the surface within sub-angstrom stability. This allows us to perform site-specific force spectroscopic measurements even at room temperature. The method has been tested in performing spectroscopic measurements on atomic positions of the Si(111)-(7×7) surface.
Nanoparticles show very interesting characteristic phenomena, such as quantum size effect or magnetic quantum tunneling (MQT). These could be due to the fact that the number of atoms in nanoparticles is much less than Avogadro constant. The future usage of magnetic nanoparticles is expected to be wide, not only to realize high density magnetic recording, but also as markers, labeling materials in the medical field by matching the nanomagnets to DNA, antibodies, or other biological molecules. We have produced magnetic nanoparticles with several nanometer sizes, including 3-d transition metals. The author introduces some of these nanoparticles, such as Ni(OH)2 monolayer nanoclusters, Fe2O3 nanoparticles and Ni-Zn ferrite nanoparticles, focusing on ferromagnetic and superparamagnetic properties. Since magnetic materials with large hysteresis are expected to yield thermal energy by external field, this effect would be an advantage for the hyperthermia treatment. Higher permeability results in an easier response of magnetization, and therefore this property would be useful for magnetic beads or delivery systems.
Experiments at a single molecular level provide spatial resolution and dynamic information for the study of biological processes under physiological environments. Here, we show several experimental results: 1) immobilization of a single-molecule in a microchannel using a combination of 3D nano-electrodes and an electrostatic force of dielectrophoresis; 2) drug delivery to a desired location, at which the molecules are immobilized, using a feature of laminar stream; 3) a microreactor for cell-free protein synthesis, as our continuous efforts to develop a micro platform for single-molecule research. For the time being, we are developing each components, however, a system including all the component will be developed in the future for an all-in-one type system to realize chip-based single-molecule analysis.
We have proposed herein a novel microfabrication method for polymer ultrathin films that utilizes fluoroalkylsilane monolayer patterned substrates and ink-jet technology. The purpose of this study is to establish the fundamental methods for site-selective formation of polymer thin film utilizing wetting contrast of patterned fluoroalkylsilane monolayer (Rf)/si-lanol (Si-OH) surfaces. Rf/Si-OH patterned surface prepared by the VUV-rays lithography have lyophobic Rf and lyophilic Si-OH phases, respectively. Polystyrene/xylene solution was used to coat the patterned surface with wetting contrast by the ink-jet method. The patterned polystyrene ultrathin films were selectively formed on lyophilic areas.
Tire performance on iced road depends on the characteristics of the ice on roads. Caused by the prohibition of application of the studded tires on the winter roads (1990-), the condition of the tires and winter roads have been varied extremely. AIST had developed the In-Door Tire Tester to study and clarify the characteristics of tires on iced roads. This paper describes an outline of this In-Door Tire Tester and inter-esting tire phenomena on iced roads obtained through the studies on this tester. One phenomenon is characteristics on the smooth ice surface and the other is the one on the rough ice surface. Namely: (1) The tire characteristics on the smooth ice depends on ice temperature and the electric conductivity of the ice for the test. (2) Braking force coefficients on the rough ice surface depend on the texture of the ice surface (amplitude and wavelength of the surface roughness).