A single test procedure for micro/nanomaterials can hardly determine their full mechanical properties. In tensile test fracture strength can be determined from the failure load at the breaking point of the material but the elastic modulus and yield strength are a bit difficult to estimate correctly for the difficulty in strain measurement. Bending test technique can suitably be used for evaluation of the elastic modulus and yield strength but it can hardly provide fracture behavior for soft materials. In this study the utility of these techniques for evaluation of mechanical properties for Platinum (Pt) wire of nominal diameter of 625 nm are discussed.

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A very-thin Pt/W thermoelectric element is fabricated on small chip. The Pt and W thin wires having the diameter of 5μm are attached on a Cu electrode chip, and these are electrically isolated by air grove on the chip. The tips of both thin wires are welded by Joule heating. The other ends of wires are connected to a voltmeter and the electro-thermal circuit is constructed. The voltage observed is proportional to the difference in temperature between the dissimilar weld and the chip (room temperature) due to Seebeck effect, and the Seebeck coefficient is found to be about 0.21μV/K. The temperature distribution of 5μm-diameter wire, where the constant current is flowing, is successfully measured by the fabricated very-thin Pt/W thermoelectric element.

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Impingement process of a small droplet on solid wall was investigated with molecular dynamics simulation technique. A liquid droplet consisting of about 14,000 particles was impinged with a given speed onto a solid wall, and change of the droplet size and the shape was analyzed. After the collision, the droplet spreads on a "hydrophilic," or strongly interacting wall, but bounces on a "hydrophobic" wall. When the wall is patterned with hydrophilic and hydrophobic parts, the droplet tends to spread only on the hydrophilic area. The droplet's initial speed is the most important parameter for droplet breakup on patterned wall.

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Nonequilibrium molecular dynamics simulations were performed for lipid bilayers with ambient water under two shear flows along the bilayer plane to investigate mechanisms of heat generation and momentum transfer characteristics in the membranes. Under parallel shear flow to the bilayer, temperature rises by viscous heating in water layer and by frictional heating at the interface between two lipid monolayers. In the lipid tail area, intermolecular interaction contributes to momentum flux positively, while negative flux due to intramolecular interaction arises. In the lipid head area, positive and negative contributions of each interaction inverts. Under perpendicular shear flow to the bilayer, temperature of lipid is higher than that of water because of the difference of heat production by viscous heating and thermal conductivity. Momentum is dominantly transferred by intra- and intermolecular interaction between lipids. From the both simulations, friction coefficient at the interface of lipid acyl chains and surface shear viscosity of lipid are evaluated.

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Molecular dynamics simulations of the magnetite-water interface with eluted ions(Fe^<2+>, Fe(OH)_2 ) were performed in order to estimate free energy profile of the ions across the interface. The purpose of examining the free energy profile is to discuss mass transfer characteristics in the vicinity of interface. The free energy profile was calculated by using the umbrella sampling and WHAM procedure. From the calculation, we show that in the case of Fe^<2+> ion, a high free energy barrier exist at the solvent surface. On the other hand, in the case of Fe(OH)_2, the free energy barrier is not recognized because the strong coulomb interaction between hydroxyl group of Fe(OH)_2 and the magnetite surface contributes decrease of the energy barrier.

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This paper presents on a method saving calculation time of molecular dynamics simulation of fluid. This method is thought about mass of molecules as one. In this method, temperature and pressure are able to be controlled by a method similar conventionally because molecules that are thought as mass move imaginarily. And, this method forms cluster of quality similar conventionally because potential field between mass and mass is revised. We call this method a united molecule model, hi this investigation, calculation time of a conventional model and a united molecule model are compared. The validity of united molecule model is discussed by shape and energy of cluster.

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Molecular dynamics simulations have been performed to investigate the effects of intramolecular energy transfer on heat conduction characteristics in bulk liquids of n-alkanes with several chain lengths. A simulation system which consists of a rectangular basic cell, where the periodic boundary condition is applied in all directions, is filled with n-alkane molecules. Artificially 'hot' and 'cold' slabs are placed at the middle and at both sides of the cell to generate constant heat energy flux in the system. Contributions of molecular motion and molecular interaction to thermal energy flux are measured in detail by applying a mathematical expression for thermal energy flux in molecular dynamic system which is extended to many-body potentials. The results show that the contribution of intramolecular energy transfer to the total thermal energy flux in n-alkane liquids increases with the extension of the molecular length when compared at the same reduced temperature and the saturation densities.

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In this paper, we focused on heat transfer characteristics in the self-assembled monolayer (SAM) system with elucidating the dominant contribution of the molecular interactions to the heat transfer in each constituent phase, i.e., the alkanethiolate SAM phase, the interface of SAM and solvent, and alkane solvent phase. By using direct nonequilibrium molecular dynamics simulations, in which the temperature gradient was imposed across the SAM interface, each component of heat flux vector, which is transferred by molecular interactions including intra- and intermolecular interactions, were separately measured. Moreover, in order to investigate the effect of the SAM modification on thermal boundary resistance of the solid-liquid interface, the bare solid interface without the SAM was examined as well. As a result, the thermal boundary resistance at the SAM interface is much lower than that at the bare solid interface.

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Protons transfer in polyelectrolyte membrane by both Vehicle and Grotthus mechanism. Due to the Grotthus mechanism, protons transfer at higher velocity in water. The mechanism, however, hasn't been widely considered in studies about proton transfer in polyelectrolyte membrane by molecular dynamics (MD) because of its complexity, whereas Vehicle mechanism has been done. This paper describes proton transfer behavior in Nafion as a polyelectrolyte membrane by MD simulation including both Vehicle and Grotthus mechanism. To treat Grotthus mechanism, Empirical Valence Bond (EVB) method is used. The potential energy barrier of proton hopping obtained by EVB method is adjusted to the computational result of Density Functional Theory (DFT). The structure of water and Nafion molecules is analyzed by Radial Distribution Function (RDF). Diffusion coefficient of proton is analyzed by Mean Square Displacement (MSD).

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A vertically aligned single-walled carbon nanotube (VA-SWNT) array, which is superhydrophobic and has high thermal conductivity, was used as a heating surface to study phase-change phenomena during pool boiling. A high-speed video camera was used observe the boiling behavior and measure heat transfer properties, and the results were compared with previous measurements using a copper surface. Additionally, the boiling surface was investigated in detail by electron microscopy.

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Microscopic contact angle on a moving contact line traveling over a step with a height of 0.3〜1.2 nm is investigated with molecular dynamics simulation. The simulations were made with a Couette flow geometry where two immiscible fluids are sheared between two parallel plates, one of which is equipped with step-structured surface. The contact lines strongly tend to be captured (pinned) at the edge of the convex step and the minimum contact angle observed at the moment of the depinning of the contact line is dependent on the height of the steps. An analytical model for the estimation of the relation between the minimum contact angle and the step height is developed. By taking account into the deviation between the normal and tangential components of the pressure distribution near the interface, the model reproduces well the increase of the minimum contact angle with the decrement in the step height.

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The condensation coefficient of water, ie., the ratio of condensation mass flux of vapor molecules to incoming mass flux at the interface, is evaluated by combining the experiment conducted by a shock tube and the numerical simulation of Gaussian-BGK Boltzmann equation applicable to polyatomic gases. Film condensation occurs on the endwall of a vaporfilled shock-tube, when a shock wave is reflected at the endwall and the vapor becomes supersaturated there. The formed liquid film grows with the lapse of time. The time evolution in thickness of the liquid film is measured by an optical interferometer, and thereby the growth rate of the film is obtained. The rate is incorporated into the kinetic boundary condition at the interface for the Gaussian-BGK Boltzmann equation, and the unique numerical solution of the vaporliquid system is obtained. Values of condensation coefficient in near equilibrium state are found to be close to that evaluated by molecular dynamics simulations at the equilibrium state.

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Molecular dynamics simulations of an argon nanodroplet evaporating into vacuum are carried out to investigate time development of its temperature. Configuration in vaporliquid equilibrium state of the nanodroplet with 3.6 nm in radius at 105 K is adopted as initial configuration of the evaporation. Although the temperature of nanodroplet decreases with time because of the loss of latent heat for evaporation, rapid temperature rise has been observed at about 8.0 ns. Radial distribution function of molecules inside the nanodroplet suggests that phase change from liquid to solid has been occurred. Recovery from the supercooling consequent to release of latent heat for solidification is thought to be cause of this rapid temperature rise.

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Dissociation process of hydrogen molecule on platinum surface was simulated by Molecular Dynamics method. EAM potential was used as an interaction between a hydrogen molecule and a platinum surface. Firstly a dissociation probability against translational energy was obtained using the potential without considering the motion of atoms. Another dissociation probability was obtained by the Molecular Dynamics simulation and they were compared with each other to analyze the effect of the motion of atoms on the dissociation probability. The results showed that the tendency of the dissociation probability is different depending on the dissociation site, for instance, top, bridge and fee site.

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In this study the correlation between thermophysical properties of low temperature hydrogen and its intermolecular potential was investigated by classical molecular dynamics method (MD). Lennard-Jones (LJ) potential, 2-Center Lennard-Jones (2CLJ) potential and modified Buckingham (exp-6) potential were applied for this calculation. MD simulations were performed at a wide density-temperature range. Equation of state (EOS) was obtained based on the MD results, and they were compared with NIST (National Institute of Standards and Technology) data. As a result, it was confirmed that the thermal properties obtained by MD results can reproduce the NIST data at gas phase, while it cannot at liquid phase and around its critical point. This distinction are considered to arisee from the many-body effect or quantum effect of real hydrogen liquid.

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In this study, we have constructed a new intermolecular potential function of hydrogen and that of oxygen for an evaluation of those thermophysical properties in some typical liquid rocket engines. The intermolecular potential energies were estimated ab-initio using Molecular Orbital (MO) calculations, and the energies were represented by a spherical harmonic expansion. In this paper, the constructed potential function has been examined through a comparison of Pressure-Volume-Temperature relationship of hydrogen, using Monte Carlo (MC) simulations.

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A thermal problem of a rarefied argon gas between two platinum walls is considered to investigate the characteristics of the reflected gas molecule at a physically adsorbed surface by H_2O molecules. The analysis is based on the molecular dynamics method for the interaction of gas molecules with the adsorbed wall surface together with the DSMC method for motion of gas molecules. The accommodation coefficients of momentum and translation energy of the molecule for the water adsorbed surface are obtained. The temperature distribution between two walls is also obtained.

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Nakamori et al. found experimentally that the friction between a partly polished diamond coating and a metal surface was drastically reduced to zero as relative speed was increased [Diamond Relat. Mater., 14, (2005), 2122]. It seems that diamond coating took off the counter surface because sliding was noiseless in their experiment. This phenomenon shows the possibility of innovative new gas lubrication system. The mechanism of generation of the lift force occurred in their experiment was unsolved although the lift force is necessary for gas lubrication. The surface roughness of the partly polished diamond-coated substrates is from 0.28μm to 0.57μm in their experiment. In the present paper, we clarify the mechanism that causes the lift force when the sliding surface has the micro-/nanoscale roughness by performing numerical simulations of micro-/nanoscale gas flows between two sliding surfaces. Since micro-/nanoscale gas flows between two sliding surfaces cannot be treated as a continuum, we use the direct simulation Monte Carlo (DSMC) method.

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To analyze micro/nano scale flows, we need to adopt a measurement technique in the molecular level. The pressure sensitive molecular film (PSMF) technique employs interaction between luminophores and oxygen molecules; hence it is suitable for pressure measurement in the flows. Previously, we researched the pressure sensitivity and the temperature dependence of PSMF. Typically, luminophores of PSMF are easily degraded by light and oxygen molecules, and it is very important to consider the photo-degradation in the measurement. In this study, we studied the photo-degradation of PSMF under two different pressure conditions to reveal the effect of oxygen molecules. Additionally, the time profile of the photo-degradation was measured. From the asymptotical behavior, it was clarified that the pre-illumination reduced the photo-degradation. We successfully obtained the pressure distribution of a micro-nozzle by pre-illuminated PSMF.

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The flow around MEMS (Micro Electro Mechanical System) is so-called the high-Knudsen number flow. The flow field cannot be treated as a continuum and the thermal conduction must not be treated by ordinary Fourier's law. In high-Knudsen number flows, the gas-surface interaction becomes important and the energy accommodation coefficient, an empirical parameter, is often used to analyze heat transport phenomena. The energy accommodation coefficient is different depending on combination of surface and gas. Thus, it is important to use the appropriate energy accommodation coefficient for each pair of surface and gas for accurate thermal management. In this report, we obtained the energy accommodation coefficients for argon and oxygen in contact with platinum surface by the Low-Pressure (LP) method, using the theoretical heat flux equation expanded to transition regime. The experimental result was compared with previous result by Thomas and Olmer (1943), which reported a relation between the energy accommodation coefficient and the surface temperature, and they are good agreement.

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We studied the scattering process of helium molecules transmitting through vertically aligned single-walled carbon nanotube (VA-SWNT) arrays using the molecular beam technique. The time-of-flight distributions were measured in order to calculate the intensity and energy of scattered molecules. Almost all scattered molecules diffusely reflected or transmitted from the surface after they interacted with VA-SWNT arrays, while few molecules transmitted axially with no interaction. It indicates that incident molecules to as-grown VA-SWNT arrays interacted with SWNT bundles, not substrate. In addition, the intensity of axially transmitted molecules strongly depends on the incident angle, due to the high orientation of SWNT bundles.

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The molecular beam technique is one of the powerful methods to investigate the gas-surface interactions in rarefied gas flows. In order to generate the high energy beam in a range of 1-5 eV without any undesirable impurities, we have been developing a molecular beam source with a non-diaphragm type shock tube which can operate at a repetition rate high enough for efficient data acquisition. The volume of our shock tube is much smaller than that of conventional ones so that the evacuation time between each shot can be made as short as possible. The small inner diameter of the shock tube leads to the strong effect of the boundary layer on the acceleration and attenuation processes of shock waves. Hence we measured the shock Mach number to optimize the tube length. The results demonstrate that the molecular beam source using the small shock tube is promising and that the optimization of the configuration will make the beam energy higher than 1 eV.

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The transient process of a liquid film flow that covers a rotating substrate in the spin coating process was analyzed by a 3-D computational simulation using the finite difference method. Evaporation of solvent and change of thermophysical properties such as viscosity was taken into account The case of nonuniform temperature distribution of the substrate was analyzed applying ring-like and spot-like high temperature region on the substrate, and it was concluded that hot ring/spot on the substrate results in large final film thickness on those ring/spot. As a special case of the spin coating, the drying process of the coating liquid on a substrate that was not rotating was also simulated, and it was found that the hot range on the substrate produces complicated profiles of the final film thickness.

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Microvalves are the essential parts of valveless micropumps and other integrated microfiudic systems. The non moving parts (NMP) valve of which geometry is fixed is a simple and reliable valving concept. This paper proposes R type valve as the improved form of 'Tesla valve' which is one of the NMP valves, and evaluated its performance numerically. In the R type valve case, diodicity was 1.37 at Re = 500 and 14% more efficient than the optimized Tesla valve. In addition, the flow characteristics of pulsating flow in low Re regime was different from those of steady flow with the identical instantaneous Re conditions.

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An investigation of the optical radiation pressure for the migration of microparticle in light-absorbing liquid is described in this paper. Optical radiation pressure from parallel or gently focused beam can generate a force on particles in liquid along the propagation direction of the ray. The viscosity reduction caused by the temperature rise due to the absorption of the laser beam induces the decrease in the viscous drag for the particle, and consequently, the migration can be promoted. Theoretical calculation based on ray optics model was performed. In experiments using microchannel and polystyrene particle with the diameter of 1.9μm, enhancement of migration velocity up to 65 % was recognized. The increment of the velocity corresponds to the local temperature rise measured by laser-induced fluorescence technique.

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Hydrogen energy system is expected as a key technology for the sustainable developing society. The surface grating technologies enable to control the thermal radiation spectrum. We are applying this technique to promote the chemical reaction to produce hydrogen. In this study, we research to make hydrogen production promoted in the process of methane steam reforming by spectrally resonant thermal radiation. The thermal radiation spectrum is adjusted to vibrational absorption bands of methane and water molecules by making a two-dimensional surface grating with microcavities on the radiative surface. By matching the peak of thermal radiation to the absorption bands of gases, it is clearly observed that the chemical reaction is promoted by the optical excitation of vibrational energy levels of molecules.

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Ignition behavior of overloaded electric wire is investigated under various gravitational conditions to know the impact of surrounding flow field on the ignition process. The experimental parameters are oxygen concentration, supplied electric current value and the applied time. The result shows that the ignition phenomenon easily occurs in non-convective flow field (in microgravity), which is characterized by lower limit of electric current to attain ignition. Moreover, as a result of the observation by Mach-Zehnder interferometry, due to a distinguished difference of pyrolysis gas motions in convective and non-convective flow field, ignition delay time and a minimum electric current leading to ignition occurrence are influenced considerably.

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The objective of this study is to establish a micro to nano-gram level mass measurement method using mechanical resonance of a cantilever type chip-calorimeter. A resonance of the cantilever with a tiny sample is automatically tuned by a positive feed back system, which detects a motion of the cantilever and shakes it after adjusting a phase of the vibration. An accuracy of the resonance mass measurement method was evaluated by analyzing an effect of a sample position on the cantilever and an added mass of air. Also, resolution of the mass measurement was evaluated with deposition and sublimation phenomena of Menthol. It was demonstrated that the measurement accuracy of 20 ng and the resolution of 1 ng.

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This paper describes a performance evaluation of a developing differential bio-calorimeter for nano-watt level metabolic heat measurement. High sensitivity is necessary for calorimeter to progress the bio-calorimetry. High sensitive calorimeter enables to reduce sample amount, to shorten the measurement time, and to discover new phenomenon. In order to sensitize bio-calorimetry, the differential bio-calorimeter with two MEMS thermopile sensors was developed. As a result, temperature fluctuation applied to the outer box of 0.128mHz decreased 1/500 with a fourfold thermostatic bath. The differential measurement with the thermopile sensors reduced the thermal noise of 0.128mHz by less than 1/4 of that for a single thermopile case.

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In this study, we developed a new artificial basilar membrane (ABM) for an animal test using guinea pigs. The geometrical configuration of ABM is designed to be fitted to the cochlea. ABM is fabricated by the microelectromechanical systems and the thin film technologies. The basic vibrating characteristics under the fluid-structure interaction are investigated using the laser Doppler vibrometer(LDV). The result indicates that ABM has a resonant frequency of 37.6 kHz, however, the frequency selectivity is not realized. To analyze the vibrating behavior in detail, the amplitude distribution along the transversal direction of ABM is compared with that of an analytical solution for a vibrating beam. From the reasonable agreement between them, it is confirmed that bending vibration is dominant in the vibration of developed ABM. The basic knowledge on designing ABM is accumulated.

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In this paper, the basic characteristics of microfabricated artificial cochlea are investigated in terms of the acoustic/electric conversion. The device has discrete electrodes on the trapezoidal membrane made of piezoelectric material to obtain electric signals generated by the local stress in the membrane. Although the sensitivity of the device can be improved by reducing the thickness of the membrane using the thin film technology, the result shows relatively small electric outputs. The reason for the small output is explored by theoretically estimating the membrane strain. Furthermore, the piezoelectric constant of the device is experimentally measured. Comparing the piezoelectric constant with a value from the literature, it is found that the measured value is extremely larger than that from literature. This result suggests that the process for the polarization should be optimized to improve the sensitivity of the developed artificial cochlea.

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Recently, clinical diagnoses applying drug delivery system (DDS), e.g. photodynamic diagnosis, have been being developed. Nevertheless, it is quite difficult to in vivo diagnose spatiotemporal distribution of drug infiltration. Previously, we proposed a tomographic visualizing assay of DDS, namely 2-Color Optical Coherence Dosigraphy (2C-OCD), which was based on optical coherence tomography using 2-Color light sources having different optical absorbance of DDS drug. In this study, the bio-availability of 2C-OCD was investigated by applying 2C-OCD to atherosclerotic rabbit aorta with macrophage marker AlPcS administered. Consequently, AlPcS accumulation, visualized by 2C-OCD, was only observed at plaque lesion significantly, and then apppered to be similar to macrophage invasion obtained by RAM11 immuno-staining. Therefore, it was confirmed that 2C-OCD could detect the drug infiltration in biomedical tissue as well as the vulnerability of atherosclerotic plaque attributed to macrophage invasion.

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Micro biochemical analysis chip have attracted attention for merits such as speed up and high efficiency of analysis. For detection, we often use immune reaction such as antibody-antigen reaction which occurs near the wall. Therefore, the concentration distribution of biomaterials near wall greatly affects detection and reaction. In this study, we attempted to evaluate interaction between the nanoparticles and the wall and to control particles for the aim of advancement of reaction efficiency. First, we measured the concentration distribution of particles 100 nm in diameter by using TERFM which expose evanescent light which intensity decay exponentially. Using this characteristic, we identified particle's 3D-position from luminance of particle. The result shows that concentration of particles drastically increases with increasing distance from the wall. Subsequently, we tried to gather particles to the wall by applying electric field to suspension. The result shows that particles moved and attached to the wall.

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There has been an increase of research into μTAS. In general, detection with this device is based on a reaction between reactants in the fluid and on the wall of a microchannel. Therefore, it is important to elucidate physical phenomena in the near-wall region of the microchannel to achieve design optimization of the device. The aim of this study is experimental elucidation of single-nanoparticle behavior in microfiuid by observation with an evanescent illumination which allows three-dimensional location measurement of nanoparticles in the near-wall region. Instead of biological molecules, fluorescent nanoparticles (20 nm diameter) were employed for the single particle imaging. Since there are issues of a measurement accuracy due to considerably small diameter of nanoparticles for the imaging and low brightness of a single nanoparticle in the deeper location, an optimal setting of shooting and a novel algorithm of image processing were proposed. The result of experiments showed that perpendicular distribution of nanoparticle concentration exists.

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We have developed the liquid crystalline micromotor driven by the backflow which is the liquid crystalline flow induced by an electric field. The liquid crystalline motors have simple structure composed of an outer cylinder, a rotary shaft and a liquid crystalline material which is filled between the cylinder and the shaft. The shaft of the motor rotates when the pulsed voltage is imposed on the liquid crystal. The rotation speed strongly depends on the voltage and the frequency of the pulse. The rotation speed increases with the increase of the voltage, and becomes almost constant for the voltage higher than 7V. It is also found that the rotation speed becomes maximum the frequency 400Hz.

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Micro pumps with various driving systems have been developed and they have been carried out with experimental and numerical approaches so far. The purpose of the present study is to develop the micro pump driven by conducting polymer soft actuator based on polypyrrole and to clarify the basic characteristics of the micro pump. Especially, we measure energy consumption of the micro pump driven by conducting polymer soft actuators and compare that results with that of the conventional micro pumps. The micro pump driven by a conducting polymer soft actuator can transport fluids in one direction without backflow by two soft actuators with opening and closing movement. The energy consumption rates of our micro pump are dramatically lower than those of the conventional micro pumps. This is because a conducting polymer soft actuator drives with a low voltage and a micro pump with low energy consumption is realized here.

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The flow in the spray coating for the three-dimensional photolithography is examined from the theoretical analysis and the experiment. The supposition that the gas flow around the three-dimensional sample gives the significant influence on the distribution of the deposited resist film is confirmed to some extent. The vortex generation and the side flow over the trench top surface give the consistent explanation about the resist bump at the vertical side wall, which is troublesome for the patterning.

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The bubble-bubble interaction through pressure pulses has been studied to show that it can be a source of cavitation noise. A recent report demonstrated that the acoustic noise generated by a shrimp originates from the collapse of a cavitation bubble. The recorded noise contains a broadband noise that consists of positive and negative pulses, but a model for single bubbles fails to reproduce the negative ones. Using a multibubble model we have shown that the negative pulses can be explained by considering the interaction of microbubbles formed after the cavitation bubble has collapsed: Positive pulses produced at the collapse of the microbubbles hit neighboring microbubbles to generate reflected pulses whose amplitudes are negative.

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When liquids are confined in nanometer-sized gaps, they have characteristic viscoelastic properties that are greatly different from those of the liquids in the bulk state. In order to clarify the mechanism of this phenomenon, we have developed a highly sensitive shear force measuring method. Our method can measure the viscoelasticity of the liquids that are confined and sheared in nanometer-scale gaps. By using the method, we investigated the gap dependence of the polymer liquid and found that both viscosity and elasticity increased drastically when the gap was decreased to a molecularly narrow width. In addition, we measured the shear rate dependence of the viscosity and found that the dependence to the shear rate increased as a result of the confinement.

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In this study, we report the flow dynamics of λDNA in a nanochannel under the electric field. The λDNA labeled by YO-PRO-1 is introduced in a nanochannel with a depth of 200 nm. Applying electric field, the flow of λDNA is successfully observed by a fluorescent microscope. The velocity of λDNA is measured at various electric fields, where the velocity linearly increases with the electric field. The diffusion coefficient of λDNA is obtained from the distribution of the velocity data to be 1.04×10^<13>m^2/s, where the value is 1/4 of that in the bulk. This result indicates that the diffusion coefficient is decreased due to the confinement of nanochannel. The result obtained here can provide important informations to design nanobio-devices using nanochannels.

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In the present study, we developed a numerical scheme to analyze the flow dynamics of biomacromolecules in a nanochannel. To include the effect of electric double layer near the wall, the electric field and the distribution of ions are modeled by the Poisson equation and the Boltzmann distribution, respectively. On the other hand, the biomacromolecule is described by the bead-spring model. The flow dynamics of 1μm long DNA in a rectangular nanochannel of 80×80 nm is analyzed based on the Langevin equation. The numerical result shows that the DNA model is extended along the longitudinal direction of nanochannel due to the electric field in the electric double layer. The characteristic time for the extension increases with the ionic concentration. Furthermore, a simple theoretical model for predicting the characteristic time is also presented. Consequently, the applicability of nanochannel for the measurement of biomacromolecule is confirmed.

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In the present study, we develop a novel model to discuss the relationship between proton transfer and overpotential in polymer electrolyte fuel cells (PEFCs) from the microscopic viewpoint. It is known that the overpotential is partly caused by the proton transfer via gas diffusion layers, electrodes, electrolyte membranes, and those interfaces. In our model, protons which are in the statistical ensemble move each layer getting across the interfaces. Here, potential barriers at the interfaces between electrodes and electrolyte membranes are assumed to disturb the flow of protons. Under the condition of constant current density, the energy dissipation process is considered, where accelerated protons collide with the surroundings, reduce their momenta, and then reach their stationary state. Consequently, the result from our theoretical model well explains the ohmic overpotential and concentration overpotential observed in PEFCs.

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In recent years, it has been clarified that single nucleotide polymorphism (SNP) is related to the incidence of cancer and hereditary disease. Therefore, the rapid distinction of SNPs in DNA sequences is important. Denaturing Gradient Gel Electrophoresis (DGGE) method is one of widely used techniques to identify SNPs. In DGGE, differences in sequences influence the displacements of DNA fragments. However, the detailed flow dynamics in DGGE are not clarified fully. In this study, we investigate the dynamics of DNA fragments in solvent medium. Here, we analyze the flow of 149 bp DNA with generalized Born (GB) model to get correspondence with the experimental data. As a result, we efficiently estimate the diffusion coefficients of 149 bp DNA and obtain highly accurate results. In addition, we discuss the relation between the collision coefficient y and the diffusion coefficient D in our dynamical computation.

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Recently, quantum molecular dynamics (QMD) is developed and used as one of preferable methods to treat interactions between atoms and electrons in complex molecular structures. In our previous study, we developed a QMD procedure to compute dissociative adsorption process of H_2 molecules on graphene layers. It is clarified that the electronic transfer plays an important role to drive the reaction. However, in the QMD computations, electrons are assumed to be usually at the ground state and their time dependent motions are ignored. Therefore, in the present study, we suggest a procedure to compute the time evolution of electronic wave functions. Compared to the atomic motions, electron wave functions transfer between the two states so rapidly. In this study, it is confirmed that not only atomic motions, but also electronic propagations between the ground states are invertible. This result mentions that the validity of the adiabatic approximation in QMD is certainly reasonable and that the electronic motions effectively predict pathways of reactions induced by the electron transfer.

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This paper describes a new method for three-dimensional transportation of liquid droplets using EWOD (Electro Wetting on Dielectric). This method makes use of surface tension and electrostatic forces, which become dominant in microscale devices. The droplet transported on a vertical or upside down surface is affected by gravity force. In order to reduce the gravity effect, volume of water was reduced and shape and size of electrodes were changed. A water droplet was transported on a inclined plate, and the angle of inclination was changed from 10° to 360° by every 10°. The results show that water droplet can be transported on all inclined surfaces. Horizontal transportation of a droplet on a vertical surface was also made successfully.

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A technique using capillary force as a method for self-alignment of micro particle is recently remarkable. This paper has proposed a technique to distribute desired liquid pattern for such method using phase transition of vapor on functional surface. A glass plate with asperity made by engraving was fabricated as functional surface. Then that plate was chilled and heated to observe the behavior of water droplets when they were condensed and evaporated. A peculiar behavior of water droplet was confirmed around the step of asperity. The relation between receding contact angle and step of asperity was discussed.

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For mechanical devices in micro or nanometer scale, interactions between surfaces have become very important. When two surfaces approach each other, in the presence of meniscus bridge by liquid film on the surface or condensed water from humid air, strong attractive force arises. And, the force heavily influences the operation of micro/nano devices. In this study, we investigate the dynamic behavior of meniscus bridge formation. Low wettability with rough surface has slower spreading speed and larger contact angle than higher wettability with smooth surface. The rough surface seems to prevent a triple point from moving.

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Chemically and/or geometrically patterned substrates allow us easily to fabricate micro-structured fine particles by using self-assembly process. This present paper intends to report some test results about alternate arrangement of different particles by using two-step drawing with particle immobilization. The patterned substrate consists of micrometer-scale grooves and mesa, the top of which are locally covered with octadecyltrichlorosilane film to be hydrophobic. 1μm-silica particles are accurately self-assembled on only micro-grooves by first drawing step from a suspension, and then chemically immobilized through a dehydration condensation reaction. Second drawing step enables 500nm-silica particles to be assembled on mesa mainly, uncovered with lp.m-silica particles. Namely, it is demonstrated that two-step drawing of self-assembly can fabricate alternate arrangements of different particles.

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Self-assembly of fine particles has an advantage of low cost, high productivity and applicability for three dimensional structures. Surface wettability is dominant factor in this process because the substrate is drawn up from suspension that contains colloidal particles. Wettability can be changed by applying microstructure on the surface and/or chemical modification. On the other hand, when fabricating trench with Deep Reactive Ion Etching (DRIE) on a silicon wafer, microstructures called scallop is formed on the trench sidewall. We demonstrate the self-assembly on the sidewall utilizing the difference of wettability between the sidewall and bottom. It was confirmed that monolayers of polystyrene particles can be produced only on the trench sidewall.

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In this research, surface modification using Nanoimprint lithography (NIL) is conducted to an adherend of the bonded joint. We developed a mold by photolithography and formed composites on the mold. Since this surface modification can be conducted within the curing time of composites, it reduces the processing cost and time, which was required for conventional surface preparation such as sand blasting or chemical etching. In this paper, experimental results of tensile test for the butt joint are reported. This paper also includes numerical analysis of the butt joint strength. We found out that pyramid-shape microstructures on the CFRP surface could improve the joint strength because peel stress was reduced by the slope of pyramid-shape microstructures.

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