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 and that of oxygen, using Monte Carlo (MC) simulations.

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Speedup of the DSMC calculation has been investigated by the parallel processing using a CPU with multiple sleds, the new intermolecular collision scheme (U-system) which enables coarse cell networks and the full equilibrium collision scheme for calculations near atmospheric pressure condition.

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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 increased to a few m/s. [Diamond Relat. Mater., 14, (2005), 2122]. It seems that diamond coating took off the counter surface because sliding was noiseless in their experiment. In the previous work, we performed numerical simulations of micro-/nanoscale gas flow between two sliding surfaces. In the previous work, we successfully reproduced lift force large enough to suspend the slider used in the experiment and found that this effect became notable only for micro-/nanoscale gas flow [IFS-Tsinghua University Joint Workshop 2009, Proceedings of 6th International Conference on Flow Dynamics, 584 (2009)]. In the present paper, we investigate the effect of configuration of micro-/nanoscale structure on sliding surface on molecular gas-film lubrication. 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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Gas flow with surface reaction in porous media appears in various regions of engineering. In porous media with holes as small as a molecular mean free path, i. e., Knudsen number Kn of gas flow in the narrow channel is in the order of unity. Therefore, the direct simulation Monte Carlo (DSMC) method is suitable to solve transport phenomena in porous media. We perform 2D DSMC simulations of such a flow. Porous media are modeled as an aggregation of randomly-placed spherical particles. The shape of narrow channel in porous media is complicated. To reduce complexity, we propose the simplification for porous structures, i. e., we simplify solid bodies in porous media as aggregations of cubes or as aggregations of polyhedra. We perform simulations with and without simplification. We compare results and investigate effects of the simplification.

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Along with the developments of the Micro Electro Mechanical Systems (MEMS), the Knudsen number, which is the non-dimensional parameter for rarefaction, of the flow inside such systems becomes large. In these high Knudsen number flows, a gas-surface interaction has become important. To illustrate the gas-surface interaction, an accommodation coefficient α is widely used as an empirical parameter. The tangential momentum accommodation coefficient (TMAC), one of the accommodation coefficients, has close relation to the pressure loss through a micro channel. Therefore, TMAC is an important coefficient for micro flow analyses. To obtain TMAC experimentally, the mass flow rate measurements in microtubes were carried out using the constant volume method. Since the mean Knudsen number was less than 0.3, the velocity slip boundary condition is applicable. The results obtained experimentally were analyzed in frame of the Navier-Stokes equation associated with the second order velocity slip boundary condition. Then the slip coefficient of the boundary condition was obtained, and finally TMAC was determined.

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The scattering of gas molecules on films of vertically aligned single-walled carbon nanotubes was investigated by molecular beam technique. The free-standing samples were employed for the detailed evaluation of the interaction between the films and gas molecules without the presence of substrates. The scattered molecules are divided to three components: reflected molecules, diffusively transmitted molecules, and directly transmitted molecules. Even for the thickness of 0.1μm, most of the incident molecules are reflected on the topmost of the films, where nanotubes are randomly oriented, and well accommodated to the surface temperature. Transmitted molecules exhibit diffusive (i.e. cosine) scattering distribution except for the direction along the beam axis, where molecules preserve their incident velocities without interaction with nanotubes.

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Single-walled carbon nanotube (SWNT) is expected to be used as one of the applications for enhancing heat exchange or sensing a small amount of gas molecules because of their large specific surface areas and their ability to adsorb gas molecules. The analysis on behavior of gas molecules inside a film made up with SWNTs is especially important for developing micro/nano devices or making film itself. Although the behavior of gas molecules scattered by the film has been investigated experimentally, the specific behavior of gas molecules inside the film has not been clarified yet. In this study, we analyzed the behavior of gas molecules inside the film by introducing numerical simulation. We calculated the scattering angle distributions and number of collisions of reflected and transmitted molecules, and confirmed relationship between diffusive movement of gas molecules and energy accommodation process.

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The micro flows such as flow around MEMS (Micro Electro Mechanical System), are so-called the high-Knudsen number flow. In these flows, the gas-surface interaction becomes important. The energy accommodation coefficient, which is an empirical parameter defined by Knudsen, is often used to analyze heat transport phenomena. The energy accommodation coefficient varies depending on the 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 results were compared with the previous results by Thomas and Olmer(1943), which reported a relation between the energy accommodation coefficient and the surface temperature. Our results are in good agreement with their results.

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To analyze micro-scale flows, we need a measurement technique of the molecular level. The pressure-sensitive paint (PSP) technique employs the interactions between luminophores and oxygen molecules; hence it is suitable for pressure measurement in the flows. However, there are few reports concerning application of PSP to fnicro-flows, because conventional PSPs are too thick owing to their polymer binders. Therefore, we had developed pressure-sensitive molecular film (PSMF) with a thickness of about 1Onm by using the Langmuir-Blodgett (LB) technique, and obtained the pressure distribution on the surface along micro-channels. PSMF is, however, inferior to the ordinary PSP in the signal-to-noise ratio, because of the small amount of luminophores in the film. In this study, based on PSP and soft lithography techniques, we have developed a novel micro fluidic channel itself has a pressure sensitive property, emitting appreciable luminescence. Additionally, we investigated the pressure sensitivity of this new PSP device, and measured the pressure along a micro-nozzle.

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We have proposed a novel patterning method of self-assembled monolayer (SAM) using near-field photothermal desorption (NPTD). This paper reports the patterning principle and the validity of the proposed method both experimentally and theoretically. The method utilizes the thermal desorption of the constituent molecules of SAM and near-field light, which can make noncontact and noncontaminated patterning of SAM in nanoscale. In order to verify the validity of the patterning of SAM using thermal desorption, the patterning of SAM by irradiating the laser beam was carried out. The result suggested that the constituent molecules were thermally desorbed. Next, analytical simulation of the temperature distribution using the finite element method was demonstrated. The result showed that the sample surface was locally heated in nanoscale by irradiating the near-field light generated by using the fiber probe coated with silver. As a result, the validity of the nanoscale patterning of SAM using NPTD was verified.

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The purpose of this study is to develop a multi-functional thermal analysis system to conduct simultaneous thermal and mass analysis of nano-gram level sample. Because the cantilever type chip calorimeter has low heat capacity, high heat resistance and highly integratable feature, it can conduct nano-gram level thermal analysis with high speed temperature scan and high sensitive thermal measurement. Furthermore, mass measurement by using mechanical resonance of the cantilever type chip-calorimeter is also possible. In this study, the DTA and thermal mass analysis of tiny copper sulfate pentahydrate were conducted with the calorimeter. In the DTA, two endothermic peaks corresponding to a mass reduction of 460ng were measured in heating phase of first temperature scan. Also, in the thermal mass analysis, stepwise mass reduction was observed through the differential analysis between heating and cooling phase data.

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Li-ion chargeable batteries are widely used for many portable devices.In recent years, markets of Li-ion battery have grown rapidly due to expansion of Electric Vehicles (EVs). The importance of improvements in its capacitance, energy efficiency, and reliability are reconsidered. We have studied to construct analytical models of Li-ion battery that predict experimental results. In charge and discharge processes, interacting with surroundings, Li^+ ions and anions flow through three regions: the electrodes, the separator, and the electrolyte. However, this mechanism is not clarified in detail due to the complexity. In particular, stable solvation shells that prevent smooth flow of Li^+ ions are considered to cause the mobility reductions. In the present study, we suggest a theoretical model and MD simulation model that treat large scale systems with coarse graining and include solvation effects. Three potentials are prepared for Li^+ and solvent molecules, for repulsions between Li^+ ions and for solvent to solvent interactions. In this paper, we focus on ion flow in electrolyte. Using this model, molecular fluid dynamics are simulated against applied electric fields and the flow characteristics are well explained by theoretical models from the microscopic viewpoint. It is indicated that more solvent molecules than the smallest solvation shell contribute to decay the Li^+ ionic current.

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Although there are a lot of experiments to observe vaporizing or burning droplets which are a simple model of spray, the droplets are usually suspended by a fiber in these experiments and the effect of fiber on vaporization cannot be eliminated. Authors propose a noncontact droplet suspension method using optical tweezers in order to eliminate the effect of fiber and report primitive experiments of the noncontact suspension in this paper. The water droplets are successfully suspended by optical tweezers system for a couple of minutes. The maximum diameter of suspended droplet is around 16μm. The experimental result using another laser system indicates that the characteristic of suspension depends on not only on the laser power but also on other factors such as laser abilities. In addition, the primitive experiment of ethanol indicates that atomizer should be developed as well as optical tweezers system due to its atomization characteristics.

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This paper reports the skin moisture device based on micro heat transfer. Moisture density of a target was measured by heat transfer across the interface. Our device consists of resistor temperature detectors (RTD) and a pressure sensor. The RTDs were also used as a heat source. Our device detected difference in moisture density of a contact object by measuring step responses of RTDs in 3 seconds. Experimental data shown for the moisture density in the human skin was actually detectable with our device.

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The bio-calorimetry measures metabolic heat of living bodies such as cells, organs, insects, seeds and so on. However, conventional bio-calorimeter with a micro-watt resolution becomes insufficient for the latest highly analytical biochemistry. In this research, new bio-calorimeter with a nano-watt level metabolic heat resolution has been developed with MEMS thermopile sensors. It is important for high sensitive calorimeter to improve both sensitivity and noise reduction characteristics. The MEMS thermopile has high sensitivity of 2.6V/W. For noise reduction cased by the room temperature fluctuation, differential method and four-hold thermostat were used. An incubator was also newly introduced. As a result, the noise reduction characteristics was estimated at 10〜17nW to room temperature fluctuation under 0.5mHz. For the thermal analysis of Yeast, the metabolic heat generation over 20nW level was measured by excepting an initial settling behavior of the calorimeter.

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This paper reports on the design and simulation of a MEMS based convective gyroscope which can independently detect three components of angular rate(3DOF). The device includes three layers in which only the layer containing in-plane hotwires requires standard MEMS process. The other layers can be fabricated by conventional machining. Jet flow in the device is generated by piezoelectric actuator which is high response and available in commerce. Therefore, the size and the cost of sensor will be significantly reduced. The sensor provides accurate measurement with small cross-sensitivity, since the integration of 3DOF measurement eliminates the sensor-to-sensor misalignment. The sensor also has high shock resistance since no proof mass is used.

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In this paper, we report the flow dynamics of,DNA under the electric field in a nanochannel. The λDNA labeled by YO-PRO-1 is introduced in nanochannels with a depth of 330, 430 and 650 nm. Applying DC electric field, λDNA is forced to flow due to electrokinetic phenomena, i.e. electrophoresis and electroosmosis flow. The flow is successfully visualized and observed by a fluorescent microscope. The dynamical behavior of λDNA is measured at various electric fields, where the velocity linearly increases with the electric field. It is found from the experimental results that the velocity is smaller than that in bulk solutions. The confinement effect of nanochannel can be seen because the velocity increases as the channel depth. Furthermore, a simple theoretical model is developed to explain the effect of the confinement. The comparison between experiment and theory reveals that the decrease of the velocity may be mainly caused by the increase of the viscous effect due to the confinement of the nanochannel wall.

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In this paper, we report vibration dynamics of the bionic auditory membrane (BAM) for a novel implantable artificial cochlea. The BAM is a long-trapezoidal and flexible membrane made of a piezoelectric material. The BAM vibrates by applying acoustic waves, resulting in the generation of electrical signals which can be used for stimulating auditory neurons. To clarify the applicability of the BAM for transient acoustic waves, the vibration dynamics were investigated based on the measurement of the reverberation induced by pulsed sine waves. The echo signals due to the reverberation were analyzed by the Fourier spectra that provided the information of the frequency selectivity. Furthermore, a theoretical model was developed to describe the wave propagation on the BAM. The results clarified the detailed processes of the wave propagation and those effects on the frequency selectivity.

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Recently, researches in the field of nanoscience and nanotechnology have received much attention. In particular, DNA is expected to be a nanoscale functional material due to the base complementarity or self-assembly characteristics. In the self-assembly process, DNA forms network structures on solid substrate surfaces in the aqueous solution. However, the detailed mechanism of DNA network formation is not fully understood. We investigate the controllability of DNA network structures by applying external electric field on a conductive gold substrate surface. Consequently, DNA networks are well observed on the cathodic surfaces. DNA molecules are densely adsorbed on the surfaces. In addition, the roughness of DNA networks is decreased as their molarity increase. It is successfully demonstrated that the formation of DNA networks is controllable by operating the external electric fields.

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Many biological procedures in endothelial cell are arranged by shear stress stimulation derived from blood flow. In the past study, the effect of shear stress stimulation on the lipid membrane fluidity is measured and revealed that the effect was variable and non-uniformity. The lipid fluidity modulation seemed to affect the action of membrane molecules. However, it is unclear about the effect of the shear stress on the dynamics of membrane protein. For this reason, we visualize a glycosil phosphatidylinositol anchored protein (GPI-AP) diffusion using photocromic fluorescent protein "Dronpa" (DG-GPI), and estimated the diffusion coefficient D of DGGPI. While 2.5min shear stress stimulation, upstream D_<up> value rose to 1.2-times of D_<up> value under static state(D=0.165±0.013[μm^2/s] (mean±S.E.) (n=27)). And upstream D_<up> was higher than the value of downstream D_<dwn>. These changes were same as the lipid fluidity modulation but were minor.

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Structural changes of the cell membrane under shear stresses are investigated by means of molecular dynamics simulations. The cell membrane is modeled as a binary bilayer composed of palmitoyloleoylphosphatidylcholine (POPC) and cholesterol molecules, where the cholesterol concentration is similar to red blood cell's membrane (〜40%). The area per lipid of the binary bilayer is smaller than a pure POPC bilayer, indicating the hydrophobic chains of the lipid become ordered with the inclusion of cholesterol. Shear stresses are imposed by the momentum change of a slab of water molecules adjacent to one side of the bilayer. We found that under shear stresses, the inclusion of cholesterol molecules impairs the deformation of POPC molecules in the bilayer normal direction, whereas it enhances the tilt of POPC molecules.

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Mechanical stimulations induce Ca^<2+> increase, which could lead to several cellular destinies. This Ca^<2+> increase behaves intricately in spatio-temporal manner. In this study, involvement of PLC activation in mechanically stimulated Ca^<2+> increase in MDCK cells was investigated with real time dual imaging of Ca^<2+> increase and PLC activation. In mechanically stimulated cells, both Ca^<2+> increase and PLC activation were observed. However, in cells neighboring to mechanically stimulated cells, only Ca^<2+> increase was observed. These results indicate that PLC activation involve in Ca^<2+> increase in mechanically stimulated cells: however, PLC activation do not involve in Ca^<2+> increase in cells neighboring to mechanically stimulated cells.

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In the vessel homeostasis, calcium wave propagation takes a important role at the point of integration endothelial cells activity. Protein Kinase C α(PKCα) is major protein as modulator of many biological procedures in endothelial cells and translocates by intracellular calcium uptake. But it is not understood whether PKCα-translocation is propagated by calcium wave propagation. Then we triggered calcium wave propagation by using PKCα-tagged-GFP. As a result, to similar to past study, PKCα-translocation was observed in stimulated cell. We confirmed that PKCα-translocation in non-stimulated cell was observed at the same time as calcium uptake, and found that intracellular PKCa tended to be localized on the edge of the stimulated cell side.

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We investigated changes in surface area and volume of fibroblasts during cell spreading on their substrate. After cell membrane and cytoplasm were fluorescently stained, cells were seeded on seven cover glasses and cultured for 0, 1, 2, 3, 4, 5, or 6 hours. Then, cells were fixed and observed using a confocal laser microscope. From the 3D reconstructed fluorescence images, morphological parameters such as surface area, volume, and adhesion area were obtained. Surface area and adhesion area increased with culture time up to 4 h, thereafter these parameters remained unchanged. Surface area increased as adhesion area increased and shape index decreased. In contrast, cell volume remained unchanged up to 6h. These results suggest that a resistance to change in volume strongly affect cell deformation, whereas a resistance to change in surface area does not restrict cell deformation during spreading on glass substrate.

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Actin polymerization-driven protrusion of the lamellipodia is a requisite step during cell migration. A cell interacts with the extracellular matrix and is affected by mechanical properties of their physical environment. The effect of actomyosin contractility generated from the interactions involving myosin II in cell locomotion is less investigated. This study focuses on the effects of the actomyosin activation on cell protrusion dynamics utilizing micropattern which has both adhesive region and adhesion suppressed region. Our results reveal that up-regulating actomyosin activity leads to an increase in lamellipodial length and increased migration across the gaps.

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In previous work, we proposed based on our measurements that nonmuscle actomyosin acts as a "mechanocontroller" in proliferative cells that allows a transient cellular response to mechanical perturbations from the set-point determined by the phosphorylation level of myosin light chain. Loss of this system results in a dysfunctional state characterized by sustained pro-inflammatory pathways. Thus, a model that only considers biochemical signaling pathways in tension regulation without also considering the autonomous biophysical contributions of actomyosin, mechanocontroller, fails to explain the transient response needed for cellular adaptation. Our study provides a molecular basis for the contribution of nonmuscle actomyosin contractility to cellular adaptation toward the physical environment that regulates cell function in physiology and disease.

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The present study hypothesized that initial geometrical shapes of cutaneous wound and the major axis of the wound to the direction of stretch could influence myofibroblast realignment observed in the maturation phase of healing process. Human dermal fibroblasts were differentiated into myofibroblasts with a treatment of TGF-β1. The cells were seeded onto a PDMS chamber either in a monolayer or in a colony of the following shapes: circle, and track fields both parallel and vertical to the stretch. Cyclic tensile stretch, with an amplitude of 20%, was provided at 1 Hz for 6 hours. Myofibroblasts seeded in the circle and the parallel track exhibited a similar response of realigning ±1:70° to the strain axis with uniformly distributed myofibroblasts in the whole area. By contrast, the cells seeded in the shape of vertical track demonstrated realignment to no specific direction. Findings supports our hypothesis, indicating that the shape and the orientation of wound influences healing processes through myofibroblasts realignment.

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Traction force generated at focal adhesions (FAs) of cells plays an essential role in regulating cellular functions. However, little is known about how the traction force at each FA changes during cell stretching. Here we investigated the changes in traction force at FAs during macroscopic stretching of porcine aortic smooth muscle cells (SMCs) cultured on elastic micropillar substrates. SMCs were plated on a polydimethylsiloxane-based micropillar array substrate. After cell spreading, the SMCs were stretched and released in their major axis direction. These stretch/release cycles were carried out with the strain rates of 0.3%/15s, and the deflection of the micropillars were measured simultaneously to obtain the traction force at each FA. Traction forces at both ends of the cells did not change significantly during the cycles with 3% strain, while the forces changed notably with 6% strain. Interestingly, these forces decreased with increase of their strain and vice versa. These results indicate that the SMCs showed active responses to keep their internal tension constant during the macroscopic stretch/release, namely, mechanical homeostatic responses. SMCs may have a strain threshold to activate these responses.

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Adult somatic cells are influenced by mechanical stresses such as shear stress, pressure and etc. Cultured cells are also affected by these stresses. Especially, many researches have been reported that mechanical stretch can regulates the differentiation of bone marrow mesenchymal stem cells (BMSCs) into tenocytes. In this study, we examined the effect of mechanical stretch under different extension ratio of 5% and 10%, respectively. The experiment results show that the protein expressions of collagen types I, tenascin-C and RUNX2 by 10% stretch are more effective regulated than by 5% stretch. In addition, the gene expressions of collagen types I and tenascin-C are up-regulated. We suggest that these results were caused because the magnitude of 5% stretch was insufficient to induce differentiation into tenocytes. Therefore, we concluded that mechanical stretch under different extension ratio causes the different responses, and 10% stretch is more adequately for the differentiation into tenocytes than 5% stretch.

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The shape and functions vary in each cell type and these factors can represent cell characters. Although the stiffness is generally important factor for material characters, it is unclear whether the stiffness can represent cell type and characters. In this study, we examined the correlation between stiffness and function of mesenchymal stem cells by using atomic force microscope (AFM).

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Mechanotransduction is the process of translating mechanical stimulation into cellular reaction, by which the live tissues adapt to mechanical environment all around and obtain extensive physiological functions. Mechanotransduction is involved in many important physiololgical processes of many kinds of tissues and plays an important role in the morphological, developmental and functional states of cells in vivo and in vitro. This paper describes the influence of FAK, RhoA/ROCK and mechanical stretch on the morphology of hMSCs, and the role of FAK and RhoA/ROCK in the mechanotransduction mechanism of tenogenic differentiation of hMSCs. We found that FAK and RhoA/ROCK are important for hMSCs to maintain the fibroblast-like morphology. We also show that FAK and RhoA/ROCK are critical to the mechanical stretch-induced tenogenic differentiation of hMSCs.

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The enzyme endothelial nitric oxide synthase (eNOS) is important factor for life activity as vascular enlargement and vascular formation. It is widely known that eNOS is localized in caveolae or golgi in endothelial cells. By immunostaining method, the modulation of intracellular eNOS localization is seemed to relate its activity (NO production). However, it is unclear that the relationship between eNOS activity and its localization in living cell. For this reason, we constructed a gene that codes eNOS tagged GFP fusion protein "eNOS-GFP" to visualize eNOS localization in living cell. In this paper, we observed eNOS-GFP distribution whether perform as wild type eNOS. By confocal Laser scanning microscope observation, we confirmedly that eNOS-GFP localized at cell boundary. This distribution is similar as wild type eNOS.

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Numerical simulations on the behavior of a red blood cell (RBC) suspended in a stationary fluid and parallel flow under steady uniform magnetic field were carried out in this study. Finite element method (FEM) and spring model were used to calculate the RBC membrane, and finite volume method was used to solve the flow field. These calculations were coupled by using the immersed boundary method. The magnetic effect on the RBC was model by considering the anisotropic diamagnetic susceptibility of the membrane components. The torque produced at each edge components was first calculated, and then the force applied to each node was evaluated. In the stationary fluid case, the RBC oriented so that the concave surface aligned parallel to the magnetic field, which corresponded to the experimental results. In the parallel flow case, the RBC oriented and remained steady due to the balance between the forces of the shear flow and magnetic field. In this case, a correlation between the inclination angle and magnetic field intensity was observed.

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Human umbilical veinendothelial cells (HUVECs) were exposed to an impact pressure of -100 kPa and changes in morphology of HUVECs and expression of vascular entodhelial (VE)-cadherin were examined in order to investigate effect of exposure to impact pressure on endothelial permeability. In the results, HUVECs exposed to impact pressure were absent locally. VE-cadherin in control were continuously expressed along peripheral region of cells. However, VE-cadherin in HUVECs exposed to impact pressure were sparsely expressed along peripheral region of cells and partly distributed in cells. These findings suggest that the exposure to impact pressure may change the expression and the distribution of VE-cadherin, influencing endothelial permeability.

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Collagen fibrils were regenerated from type I collagen solution (3 mg/ml,pH3.0). The mass of collagen molecules adsorbed on the regenerated collagen fibrils was measured using a QCM, and the microstructure of the fibrils was observed using an AFM. The collagen molecules were adsorbed on the failure points of the regenerated collagen fibrils cut by a surgical knife.

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Nonmuscle actomyosin or actin stress fibers play an essential role in cellular adaptation to physical environment, yet the relation between their function and structure remains poorly understood. Herein, we provide the first evidence that stress fibers twist during contraction or stretching. We directly pulled or induced MgATP-based contraction of stress fibers isolated from the substrate. Twisting motion was observed in both cases, suggesting that stress fibers have a helical structure. Given that stress fibers are dynamic organelles that bear tensile stress in appropriate places inside cells, the helical structure seems to be advantageous as it is easy to disintegrate when compressive force is applied, serving as a ready source of actomyosin to reassemble new stress fibers.

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In few decades, with the increase of a cardiovascular disease, e.g. acute coronary syndromes. Unstable plaques predisposed to rupture, causing acute coronary syndromes, are characterized by thin fibrous cap covering a large lipid core. Therefore, a non-invasively diagnosing system of tissue properties with micrometer scale has been crucially promising to detect vulnerability of cardiovascular disease. In this study, "Attenuation. Reflection and Variance OCT" (ARV-OCT) is proposed as a tomographically visualizing technique of tissue characterization. This is based on spatial fields of scattering attenuation, reflection and variance in an OCT image. ARV-OCT was ex vivo applied to atherosclerotic plaques of rabbits. As a result, three parameters were separately correlated fibrous and lipid comparing with histological images. Consequently, the present method has a highly diagnosing potential of tissue characterization of atheroscherotic plaques.

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The artery walls consist of structural components that have various mechanical properties: elastin, collagen and smooth muscle cells. Such variety may cause heterogeneous deformation of the components at a microscopic level when arterial tissue is subjected to macroscopic uniform stretch. To examine this hypothesis, we sliced 15-μm-thick specimens from porcine thoracic aorta with cryotome, and stretched them under a transmitted light microscope to observe their microscopic deformation caused by macroscopic stretch. Microscopic strain was found to be highly heterogeneous: stretch ratio in the elastic lamina (EL) and smooth muscle layer (SML) was 1.1-2.3 and 1.1-2.1, respectively, at circumferential stretch ratio of 1.5. Strain difference between an EL and a SML adjacent to each other could be as high as 6 times. These results suggest that the microscopic deformation in the artery wall is highly heterogeneous. Mechanical environment of the artery wall might not be so homogeneous at a cellular level.

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This paper describes the fabrication of Au nanowire utilizing porous aluminum. To fabricate nanowires, at first Au film with the thickness of 100 nm was evaporated on one side of porous aluminum as a conductive working electrode. Nanowires were obtained via electrodeposition under a constant electrical potential about -3 V in 40g/l KAu(CN)_2, 100g/l KH_2PO_4 aqueous solution at room temperature. After etching in 3 M NaOH aqueous solution to remove porous aluminum, nanowires with the average diameter of 200 nm and length 8 approximately, were observed by scanning electron microscope. It was confirmed that the nanowires consisted of Au by energy dispersive X-ray analysis.

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Out-of-plane elastic stiffness of Co/Cu superlattices with different Cu thicknesses is determined by picosecond ultrasounds method and x-ray reflectivity analysis, and relationship between the stiffness and the interfacial structure is discussed. Considering the simple rule of mixture, macroscopic elastic stiffness of a Co/Cu superlattice monotonically changes as the thickness of a Cu layer increases. However, determined elastic stiffness showed an oscillating behavior, the period of about 10 A, which was similar to the reported Cu thickness dependence of giant magnetoresistance. Out-of-plane strain of Co/Cu superlattices also showed an oscillation behavior, and we observed that interfacial strain contributes on the stiffness.

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The growth of electromigration induced Al split micro-tubes in passivated aluminum films was investigated. The sample was a polycrystalline Al line covered by a passivation layer. A slit and a hole were introduced at the anode end by wet etching and focused ion beam technique, respectively. Al atoms could be accumulated to cause a compressive stress after we started to supply a direct current. The split micro-tube grew with the increase of the current supply time to release the stress. It is found that the roots of discharge holes play a key factor in the growth process. The root up to the Al/TiN interface was able to effectively release the compressive stress.

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Various methods have been proposed for fabricating nanocoils in order to extend the range of elements for building nanodevices. Most of these methods are based on self-assembly technique. We have previously demonstrated an alternative method in which a straight nanowire is bent by depositing a thin film on the nanowire. The bending is due to the misfit strain of the coated film. However, nanocoil formation using this method is highly inefficient. In this study, we developed an advanced method in which the helical formation of coated nanowires takes place because of the viscous flow of the core material, i.e., the nanowires, and the misfit strain of the coating film. When the melting temperature of the nanowire material is lower than that of the coating, elevating the temperature induces a viscous flow, i.e., creep, which only occurs in the nanowire. The creep releases the constraint of the nanowire on elastic bending due to film strain.

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A technique of producing metallic nanostructure by utilizing electromigration has been proposed. Electromigration is the phenomenon that the metal atoms are transported by electron wind due to high density current. A numerical simulation method of nanostructure formation utilizing electromigration was recently developed based on the governing parameter for electromigration damage, AFD_<gen>. However, the simulation did not cover the period of specimen's damage. In the present study, the numerical simulation method of the nanostructure-production technique is developed considering electromigration failure of specimen. The results of the simulations are verified comparing experimental results. A good agreement between them is found in the produced nanostructure volume. The simulation is expected to be useful for identifying conditions for nanostructure production.

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Two types of manipulations using van der Waals force and Joule heating have been demonstrated for silver nanowires in a scanning electron microscope. In both cases, Silver nanowires with diameters of about 250 nm were fixed onto tips of probes and manipulated in three dimensions. Two silver nanowires also were successfully welded by Joule heating. Welding was performed by applying a constant current to the wire system where the free ends of two silver nanowires were contacted It was confirmed that Joule heat welding was applicable over a wide range, and realized the welding of silver nanowires.

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Static and sliding frictions of probe sample contacts play a vital roll on the micro/nanomanipulation of nanowires. In this study, using a new experimental method, the normal contact force and the friction force between the very-thin Pt wire and W probe has been measured accurately by using a single sensor. In the method, the force required to axial pullout of Pt nanowire against the local contacts of closely positioned two opposite probes is determined with the variation of normal pressure and sliding speed. The static friction coefficient is found to be dependent on sliding speed whereas the kinetic friction coefficient is found independent of the sliding speed.

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It has recently been observed that metallic glass nanowires are formed during the breaking of bulk metallic glass. Metallic glass nanowires can easily been bent, and their strength is as extremely high as the strength of bulk metallic glass. In this paper, Cu-Zr metallic glass nanowires of amorphous structure are formed in the melt-quench simulations based on the molecular-dynamics method. The uniaxial tensions are imposed on these nanowires. Their Young's modulus and the deformation characteristics are examined.

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We present a novel nondestructive inspection technique for nanowires using picosecond ultrasound spectroscopy. Resonance frequencies of nanostructures are highly affected by their elastic modulus and the boundary conditions. Defects in a nanowire should lower the elastic modulus and then resonance frequencies decrease. If detachment appears, the elastic waves which had been generated from nanowires and propagate toward the substrate, will disappear. Therefore, the damage accumulation in nanowires and adhesion strength with the substrate can be evaluated by measuring mechanical resonance frequencies of nanowires. In this study, we measure resonance frequencies of Cu nanowires fabricated on Si and glass substrates using the electronbeam lithography. We succeeded in observing the through-thickness resonance and Rayleigh-wave resonance related with the nanowires. During the electromigration, the through-thickness resonance frequencies significantly decrease, remaining the Rayleigh-wave resonance frequencies unchanged, indicating defect accumulation inside the nanowire without detachment.

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To confirm the sensitivity in the measurement of electrical properties affected by the nano structure of microwave AFM (M-AFM) probe, three kinds of M-AFM probe with a nano slit on its tip in different width (75nm, 120nm and 160nm) were investigated. Au and glass samples were measured by the probes working at a noncontact AFM mode. The M-AFM probe with the nano slit having the width of 75nm, by which the difference of the measured voltage between Au and glass samples is 55.1mV, shows the highest sensitivity for detecting electrical properties of materials. As the result illustrated, the M-AFM probe with smaller width nano slit on the tip is considered to be an ideal nano structure.

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A thin film polyimide diaphragm for a MEMS actuator is investigated on process and mechanical characteristics. According to the low elastic modulus and the thin film process, a thin film polyimide diaphragm has a possibility to become an actuator producing large displacement. In the process, spin coating is used for making a thin film of polyamide. Then the polyamide turns into polyimide by baking. For the diaphragm, deep-RIE (Bosch process) is used to remove a silicon substrate. We are able to process the thin film diaphragm with the thickness down to 2μm in this method. To use the diaphragm as an actuator, we choose heat expansion as a driving method. Aluminum thin film is deposited on the diaphragm for applying an electric current. It is confirmed that this system works as an actuator by controlling a current.

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This paper describes an analytical study of white noise in electrostatic MEMS devices. Two noise sources are taken in account, thermal noise and semiconductor interface trap noise. We simulated the noise voltage appeared in the capacitance of an electrostatic MEMS device using AR (autoregressive) equation and found that the interface trap noise is greater than the thermal noise. This suggests that some treatment annihilating such traps is necessary to reduce white noise in MEMS devices.

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