Osteoarthritis of the hip occurs from an abnormality in the shape of a hip joint. During the progression of osteoarthritis, a fluid-filled cavity called "bone cyst" appears and enlarges in cancellous bone, which leads to fracture around the cyst in the bone tissue. Because osteoarthritis relates to the mechanical condition of the bone tissue, it is probably expected that the growth of a bone cyst progresses with bone remodeling. Elucidation of the growth process of a bone cyst is thus important for understanding the mechanism of osteoarthritis of the hip. In this study, we estimated changes in the trabecular morphology around the bone cyst using our bone remodeling simulation method using three models, which are a normal model, high density model and low density model at the peripheral region of the bone cyst. As a result, we found differences of morphological change around the bone cyst between the high and low models. Bone resorption occurred in the high density model, while bone formation occurred in the low density model on the periphery of the bone cyst. These results correspond with the clinical report; a region of high bone density appears around bone cysts in osteoarthritis. The efficiency of our simulation method to understand the mechanism of bone cyst growth is discussed.

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Vinculin family (VF) proteins are involved in cell adhesion protein complex. In addition, it is supposed that forces exerted on the adhesion complex are sensed and converted into chemical signals by VF proteins. This mechanosening function can be based on force-induced conformational changes of VF proteins, especially, conformational changes of alpha-helix bundles, the common motif of VF proteins, play an important role on the mechanosensing function. To investigate force-induced conformational changes of proteins in an atomistic scale, steered molecular dynamics (SMD) simulations have been performed as a computational microscope. However, SMD is limited to obtain submicron second time-scale dynamics because of calculating very massive degrees of freedoms of atoms. Therefore, to complete the protein conformational change within a certain time scale, applying forces employed in SMD simulations are usually much higher than those in vivo. This overlarge force often induces unnatural conformational changes. Although these limitations would be resolved by future high-performance computers, biological scientific demands in seeing how proteins are deformed by forces are increased rapidly and become an urgent issue in mechanobiology. Thus, in this study, we investigate conditions of SMD simulations for alpha-helix bundles to avoid unnatural conformational changes as much as possible even in a short time scale. Examining several conditions about locations of points of application of forces, we found that one condition reproduces a desirable conformational change of the helix bundles, while the steric structure of each helix was maintained to be the alpha helix.

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We have performed molecular dynamics simulations of phospholipid bilayers under stretching, in order to understand the detailed mechanisms of rupture of red blood cell membranes (hemolysis). In this study, we performed unsteady and quasistatic stretching simulations for phospholipid/cholesterol bilayers, which are expressed by applying the equibiaxial stretching algorithm that is the proportional scaling of both the atom positions and the system box lengths. We investigated the effects of the stretching speed on (i) the critical areal strain where the rupture occurs, (ii) the relationships between the tension and the areal strain of the bilayer, and (iii) the stretch-induced phase transition from Lo to L_βI phase, in the cholesterol-including bilayers. We found that the critical areal strain in the unsteady stretching simulations are larger than that in the quasistatic stretching simulations, in agreement with previous experimental observations. In both the stretching simulations, the tension of the bilayer non-monotonically changes with the increase of the areal strain. The tendency of the relationship between the tension and the areal strain is insensitive to the stretching speed. The non-monotonic relationship between the tension and areal strain of phospholipid/cholesterol bilayers is significantly different from the monotonic one of pure phospholipid bilayers reported in our previous study. From the visual inspection of the snapshots of the stretched bilayers focusing on the orientation of the phospholipid molecules and the bilayer thickness, the phase transition from Lo to L_βI phase is observed in both the stretching simulations.

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In an in vitro experimental observation of tank-treading (TT) motion of a red blood cell (RBC), which is defined as the cell membrane's rotation around the interior, Fischer (Biophys. J., Vol. 86, pp. 3304-3313, 2004) observed that the outer rim of the RBC membrane is always formed by the same part of the membrane before and after membrane excursion by the transient fluid shear flow. In this study, we propose a numerical simulation of the Fischer's experiment to investigate effects of membrane's viscoelastic properties on the shape recovery mechanics.

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Numerical simulations were carried out for venous thrombus formation depending on the shear strain rate and its duration time. Blood components were modeled by an assembly of computed particles and the fluid mechanics was solved by the MPS method. A spring force was used to express blood aggregates that form thrombi. In two-dimensional numerical simulations with a stenosed channel, thrombi formed at the stagnation and recirculation region that appeared downstream of the stenosis. About parameters included in a thrombus formation model, the more thrombi were formed with the larger threshold value of the shear strain rate and with the smaller duration time. The distribution of thrombi along the flow channel was qualitatively consistent with a milk clot experiment.

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Coronary circulation has the important role for myocardial infarction. In recent years, computational simulation has revealed knowledge about heart dynamics. Especially multi-physic and multi-scale heart simulator "UT-Heart" has great contribution on this field. However, UT-Heart cannot calculate peripheral resistance on microcirculation of coronary circulation accurately. In this research, we are performing three dimensional simulation on microcirculation of coronary circulation in order to improve calculation accuracy of UT-Heart. We show the effort and the state of this research in this paper.

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FSI analysis for hemodynamics is a major method to elucidate vascular disease. Therefore, it is important to apply an appropriate boundary condition based on the physiological state. However, CT or MRI medical images only delineate vascular shapes under normotensive condition. For this reason, we have been developing a method to predict the vascular shape at no load state. Both normotensive and no load models are used to conduct FSI analyses with the same boundary condition. The result shows that the wall share stress depends on the initial stress condition in the vessel wall.

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Hemodynamics can be a key factor associated with the onset and progress of aortic aneurysms, which are normally triggered by atherosclerosis. This study is aiming to clarify the aortic aneurysm hemodynamics with consideration of wall deformations and to evaluate the wall shear stresses and energy loss with rigid and deformable vessels by introducing two indices of the pulsatile pressure index (PPI) and the pulsatile energy loss index (PELI). A realistic three-dimensional computational fluid dynamic model of aortic aneurysm is constructed based on medical images and is further connected to a 0-1D model for the whole cardiovascular system, which provides both boundary conditions of pressure and flow-volumetric rate waveforms at inlet and outlet as well as vessel wall deformations. Our result shows that the wall deformation can result in significant differences in a three-dimensional, and hence points to the importance of considering the influence of vessel compliance in evaluation of the pulsatile flow energy loss.

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Bicuspid aortic valve (BAV) is a congenital heart disease, which may trigger off the ascending aortic aneurysm. Some previous observations reported the statistic relationship between BAV and aortic aneurysm. However, hemodynamic effects of BAV on aortic aneurysm are still unclear yet. In this study, we conducted a computational fluid dynamic study by combining image-based left ventricle (LV) and aorta models in order to provide an integrated investigate on BAV hemodynamics. Three-dimensional blood flows in both LV and aorta are treated as laminar flow and computed by solving the Navier-Stokes equations; boundary conditions in terms of pressure curves of ascending aorta, left ventricle and left atrium based on zero dimensional (lumped model) model are imposed at inlet and outlet. Furthermore, opening and closure of the aortic valve are modeled and controlled based on physiological data at mitral and aortic valves. Our results demonstrate that the BAV causes somehow instable vertical flows behind aortic valve, which results in a high oscillation shear index (OSI) distribution in the ascending aorta.

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Skull fracture and cerebral contusion are caused by the translational acceleration on to the head. Cerebral concussion and DAI (diffuse axonal injury) are done by the rotational one. The sagittal rotational acceleration causes concussion and the coronal one does DAI. The pulse duration of the acceleration by which DAI can be caused is longer than the one for concussion. WSTC (Wayne State University Tolerance Curve) says that concussion can be caused by the translational acceleration rate of 90 G and over. According to some other studies, DAI tolerance limit is identified as follows: the rotational acceleration rate of 6,000-7,000 rad/sec^2, or 7,500 rad/sec^2. Few reports say that cerebral contusion may occur at the translational acceleration rate of 150 G, 180 G, 250 G, or 195-300 G (30,000-44,500 rad/sec^2). However, there may be no conclusive report about the level of the translational acceleration on to the head which can cause the cerebral contusion.

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Diffused Axonal Injury is a type of head injury which occurs frequently in traffic accidents. It is said that it is caused by rotational head movement, and elucidation of the mechanism is necessary. There are three factors affecting the occurrence of DAI based on the intracranial structure; A complicated brain and skull structure, relative motion of the brain and skull with cerebrospinal fluid present?, and the restraint of the brain motion due to cerebral flax and tentorium cerebelli. Although various studies are done based on these three factors, it is difficult to reproduce in solid-model and simulation model, and while the influence of three factors in computational dynamics has been unknown, the simplification of the model is performed in the simulation. In this study, constructed the head neck solid-models which the intracranial structure factors differ, and considered the influence of an intracranial structure factors. The experiment which imitated the collision from the side was conducted on three sorts of the head neck solid-models, and brain depths distortion was measured. It turned out that the experimental result of three sorts of head neck substance models is compared, and it has influence with relative motion important for brain depths distortion between a brain slot and a brain-skull.

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To elucidate the mechanism of mild traumatic brain injury (MTBI), we developed a new FE model of the human brain including the brain central structure including the Corpus callosum, Fornix, Basal ganglion, and so on, which is supposed to be possible axonal injury locations for the MTBI. In the developed brain FE model, we reproduced the shape of each part and the connectivity in the brain central structure based on the anatomical texts. The number of elements of the brain FE model is about 60,000, and the time step is 0.357 micro seconds. The model was validated against displacements of some target points in the cerebral tissue during a head rotational impact. The displacements in the parts close to the central structure in the brain tissue predicted by the model showed good agreement with those obtained from cadaver test data. One of the injury locations predicted by using the maximum principal strain agreed well with one of locations of the MTBI reported by medical doctors. Therefore, the brain FE model proposed in this study has the potential for more accurate prediction of the MTBI.

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In this study, reproduce the biological impact experiment by a computer simulation was analyzed to compare the injury point of the brain cells and the stress distribution of computer simulation. Sheep head model was constructed by voxel method from CT images and MRI images. The impactor and the skull defined as a rigid body in the analysis. The material property value of simulation model were changed (CSF, dura mater, falx, and tentorium). As a result, high stress (more than 10kPa) is generated in around the press-fit point. Maximum von mises stress of around the impact points are increased by changing the material property value, correlation between Maximum von mises stress and injury point is noticeable in comparison with the previous model.

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DAI is caused by sudden inertial loading to the head associated with rapid deformation of brain tissue, resulting in the stretching of neural axons. Periodic swellings along axons and axonal bulbs at disconnected terminal ends of axons that are the morphological hallmarks of DAI pathology lead to the disconnection of neuronal cells from tissues, resulting in cell death. The β-amyloid precursor protein (β-APP) that is conveyed by axonal transport accumulates where axonal transport is disrupted. The cultured rat brain neuronal cells were stretched to a strain of 0.10, 0.15, 0.22, or 0.30 at a strain rate of 11, 21, 27, or 38 /s. The sham control is put in the stretching device without mechanical loading and then is incubated under conditions of 5% CO2 and 100% humidity at 37℃. β-APP was stained at 3h post-loading and observed using fluorescence microscopy. As a result, β-APP accumulated in swellings and bulbs following stretching and β-APP-accumulated axons significantly increased following a strain of 0.22 with a strain rate of 27 /s and a strain of 0.30 with a strain rate of 38 /s in a stretch-dependent manner compared to sham control. These results suggest that the threshold of interruption of axonal transport is strains of 15-22% at strain rates of 21-27/s and the accumulation of β-APP is a quantitative marker for traumatic axonal injury at a cellular level.

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A full-body human multi-body model of a typical Japanese female was newly developed in order to clarify the influence of gender difference on occupant responses during rear collision accident. The characteristics of the human model were defined according to the published outer body geometry, joint characteristics and inertial characteristics data of Japanese females. The human model was then validated against rear impact test using female volunteers by reconstructing the conditions of the test. The human model could reasonably reproduce the volunteer kinematics, demonstrates that the human model can simulate female occupant kinematics during rear collision accident. By comparing the responses between the female model and the previously developed male model, gender difference was considered to have remarkable effect on the occupant kinematics that may lead to different injury outcome.

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It was reported that the seat arrangement with rotating seat inward or outward improves occupant's comfort. The seat rotational function can be put into practical use with consideration for the influence of occupant safety in a collision. In this study, the influence of rotating seat in side impact was clarified by using MADYMO simulation software. The quality engineering was carried out and effective parameters were clarified to control the impact behavior of occupant and to reduce head and chest injury criteria.

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The purpose of this study is to clarify the influence of time degradation and strain rate dependence for mechanical characteristic of soft tissue. Impact tensile testing machine was developed and impact tensile test was carried out using pig liver by changing storage time and strain rate. Experimental results suggest that the mechanical characteristic is influenced with cooling storage time at high strain rate. Also, maximum stress tend to depend of strain rate, however that can't be concluded because number of tests is not enough. Therefore, impact tensile test is carried out continuously.

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In a vehicle accident, the occurrence of spinal injury can have a significant impact on life support and life of recovery. In general, spinal injury is required high axial compressive force and vehicle occupants behavior at time of collision are related. In this study, sampled 14 cases of thoracic and lumbar spine injury from 177 research data of the in-depth study by Nippon Medical School and Nihon University. Moreover, we analyzed for thoracic and lumbar spine injury trend. As a result, lumbar spine injury accounted for 79% of the thoracic and lumbar spine injury. Compressional fracture and burst fracture accounted for 46% of the lumbar spine injury. In the frontal crash and seatbelt wearing on vehicle accident, compressional fracture caused by hyper flexion at the passenger forward bending exercise. Burst fracture caused by pitching motion and thrust force at riding the curb.

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Transient cell membrane permeabilization by using ultrasound with the aid of microbubbles, i.e., sonoporation, is one of promising techniques for non-invasive drug delivery system. To improve the efficiency of successful sonoporation and the survival fraction of cells after the procedure, various in vitro sonoporation systems have been developed. Here, we report how experimental settings of the Well-on-Water-Surface (WWS) type in vitro sonoporation system affect the survival fraction of cells under sonoporation conditions. By changing the medium height of the cell culture dish by 0.1 mm, we measured the peak pressure amplitude in the dish during exposure to 1 MHz continuous wave ultrasound and counted the number of viable cells before and after exposure to the ultrasound with the aid of 0.1 ml/dish microbubbles SONAZOID[○!R]. Under the experimental condition, the peak pressure amplitude varied in the range from 0.4 to 0.6 MPa, and the survival fraction, the fraction of the number of viable cells after the procedure, from 25 to 85 %, which may be explained by the effects of standing wave in the dish. For the better estimation of sonoporation efficiency in the WWS type sonoporation system, the medium height in the dish should be set carefully.

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This paper describes development of regenerative medical system using microcapsules including gas by shock waves. Special polymer microcapsules were made, their structure is composed gas, liquid and membrane. To observe deformation process and disintegration of microcapsule, the pressure waves generated by piezoelectric device were applied to their microcapsule. By observing these capsules during working pressure waves, it was found that deformation of a bubble inside polymer capsule is large by selecting the proper parameters such as gas ratio and thickness. Also, numerical calculation model were made to examine effect of gas ratio and thickness on the deformation. As a result, it was found that initial location of bubble b_0, initial pressure in the bubble P_0 and liquid viscosity μ affect the deformation process.

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Chemotherapy for cancer plays a significant role in clinical situation. Systemic administration of anti-tumor agents causes drug dispersion in the whole body, however, this leads to poor efficacy in lymph node (LN) metastasis and severe side effects due to cytotoxicity to normal tissues. In this report, our aim is to develop a novel treatment method for LN metastasis. Our findings show that the lymphatic administration of drugs, doxorubicin, with a combination of nano/micro bubbles (NMBs) and ultrasound (US) enhances antitumor effect. When the solution of doxorubicin and NMBs were injected into the subiliac LN, they reached the tumor-bearing proper axillary LN (proper-ALN) through lymphatic vessels. Subsequently, the proper-ALN was also exposed to US. The NMBs with US exposure could increase cell membrane permeability transiently, resulting in the delivery of doxorubicin into the tumor cells in the LN efficiently. Furthermore, lymphatic administration inhibited acute toxicity compared to systemic administration. Our results demonstrate that the lymphatic administration of US with NMBs has a potential for the treatment of metastasis.

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Bone remodeling, which plays an important role in maintaining bone homeostasis and its structural adaptation to mechanical environment, is regulated by various kinds of molecular signals. Wnt signaling is one of the most important factors in bone remodeling, particularly in bone formation. To reveal the Wnt signaling and its inhibition mechanisms, we measured the interaction between Wnt signal receptor, LRP5, and its signaling molecules, Wnt3a, Dkk1, and Sclerostin, by using Atomic Force Microscope (AFM). In this study, we calculated the dissociation constants of Wnt3a/LRP5, sclerostin/LRP5, and Dkk1/LRP5, and it was proved that the dissociation constant of Dkk1/LRP5 is about 10-times smaller than that of sclerostin/LRP5, that is, the bond life time of Dkk1/LRP5 was about 10-times longer than that of sclerostin/LRP5. As the results, we quantitatively verified a previous suggestion that Dkk1 may function as a main regulator of Wnt signaling, and that sclerostin, which is more selective in its activity and restricted in its expression, may function as a more refined regulator of Wnt signaling.

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Micropatterning is becoming a powerful tool for studying morphogenetic and differentiation processes of cells. Here we present a new micropatterning technique in which polydimethylsiloxane (PDMS) substrates were treated with oxygen plasma, and the resulting hydrophilic layer of the surface was locally peeled off through a direct contact with a peeling stamp. A hydrophobic layer of PDMS substrates could be selectively exposed only at the places of the physical contact, allowing for spatially selective adhesions of cells. Chemical bases for the successful cell micropatterning were confirmed with water contact angle measurements and X-ray photoelectron spectroscopy.

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Cell adhesion is important to cell function. Focal adhesions (FAs) are large protein complexes organized at the basal surface of cells, which physically connect the extracellular matrix to the cytoskeleton and maintain the form of the cell. However, how the focal adhesion morphology change during cell adhesion to the extracellular matrix is still not clear yet. In this study, we used a MC3T3-E1 cell line as the test model. We plate the cells whose cycle had been synchronized by serum starvation on glass bottom dishes and cultured them for 10, 20, 30, 40, 50 min, and 1, 3, 6, 9, 12, 15, 18, 21, 24 h, then stained the F-actin, vinculin and nucleus and observed their change of morphology. We measured the cell area A_<cell>, number of FAs per cell N_<FA>, mean area of each FA A_<FA>, total area of FA per cell TA_<FA>. We grouped the FAs into three categories (small, middle, large) depending on their area and calculated their ratios to N_<FA>. The results revealed that A_<cell> increased generally, and these parameters about FA were simply changed until the cell area after cultured for about 1h. However they had different time course changes afterwards, especially around 3-12 h and 21-24 h after plating. These changes might indicate that dynamics of FAs is influenced by cell cycle.

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Protein kinase C α (PKCα) in endothelial cell is activated by Ca^<2+> and diacylglycerol (DAG). Recently, our experimental study showed that activated PKCα was translocated to membrane site by various stimulations. In this study, to understand this mechanism, we developed a computational three-dimensional (3D) model of PKCα translocation based on our experimental data. In expreiments, we found a time lag between Ca^<2+> diffusion and PKCα translocation. We used RICS System (RIKEN) which can caliculate the biochemical reactions and molecules movement. We reconstacted 3D cell model from confocal microscope image data and built a biochemical mode with Ca^<2+>, PKCα, and DAG. We simulated this PKCα translocation with the RICS system, so that we will study various drugs stimulations.

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It is well known that mechanical stimulation regulate the biological functions such as differentiation. In particular many researchers have been reported that mechanical stretch can regulate the differentiation of bone marrow mesenchymal stem cells (BMSCs) into tenocytes. But rigorous relationship between cell differentiation into tenocytes and mechanical stretch is not clear in detail because a conventional stretched chamber does not provide uniform strain to cultured cells. In this study, we tried to develop a new experimental system that can provide cells uniform strain. In this paper the structure of new chamber was developed by FEA in order to create uniform strain on the membrane cultured cells. The present result suggested that the structure of the new chamber could give uniform stretch on the membrane better than old one and the variability of the strain on the membrane was also very small.

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Cells are continuously exposed to the mechanical stimulus such as the cyclic stretch due to heart beats. The cells are aligned nearly perpendicular to the direction of the cyclic stretch. Recent reports indicate that the pathological levels of cyclic stretch cause apoptosis. The balance of the mitochondrial fusion and fission influences the state of the cell. Thus the change in the mitochondrial morphology affects cells function and homeostasis. Therefore we investigated the effect of the cyclic stretch on the mitochondrial morphology of the bovine aortic endothelial cell (BAEC). Mitochondria was dyed by 1.0 μM mito-tracker orange (Ex.:554 nm, Em.:576 nm), and cells are subjected to the physiologic levels of the cyclic stretch (5% at 1 Hz) and the pathologic levels of the cyclic stretch (20% at 1 Hz) for two hours. It was observed that the length of mitochondria hardly changed when the physiologic levels of the cyclic stretch was applied while the length of mitochondria gradually shortened when the pathological levels of the cyclic stretch was applied.

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Cell manipulation system is an essential tool for reconstruction of cellular microenvironment that leads to high-throughput function analysis. In this paper, we developed a cell manipulator array integrating a cell trapping function on tips, which is a major part of the cell manipulation system. To transport cells electrically, an electrokinetic pump was fabricated and bonded to a PDMS sheet. This pump generated suction and ejection flows through a punched hole. The flow was characterized by measuring trajectory of fluorescent particles. We fabricated electrode pairs for dielectrophoretic cell manipulation. Cells were trapped in between the electrode pairs. We characterized viability of the trapped cells and studied the effect of AC voltages on cells.

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Gap junctions have been known to be involved in regulations of cell functions. It is also suggested that gap junction intercellular communications (GJICs) between tenocytes play an essential role in collagen synthesis in response to mechanical loadings. However, there were little knowledge on how GJICs are mechanically regulated and how changes in GJIC affect tenocyte functions. Accordingly, the present study has proposed a new numerical model to estimate intra- and intercellular diffusivity, based on one-dimensional diffusion theory, by fitting the model to data obtained from FLIP experiments, which visualises intercellular mass transport using a confocal laser microscope. Tenocytes were seeded within microgrooves integrated in a custom-made PDMS device, and were loaded with calcein-AM. FLIP experiment consisted of a series of instantaneous 100% power laser irradiation provided to one of tenocytes in a series every 2.6 second for 99 times, and fluorescence decay profiles of the targeted tenocyte and its neighbouring cells were obtained. Using the numerical model, intracellular and intercellular diffusion coefficient of tenocytes under static culture was estimated to be 25.3 and 1.06 μm^2/sec, respectively. The latter was significantly increased by an application of physiological, 4% tensile strain to the tenocytes, whereas that was significantly reduced by excessive, 8% tensile strain to the cells. Therefore, it can be concluded that physiological mechanical loading enhances intercellular communications, whereas non-physiological, overloading disrupt them.

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This paper explores thermal spreading resistance variation by boundary condition difference which causes heat flow difference, assuming a motherboard in slate style chassis of tablet device. Simplified motherboard model is employed and thermal spreading resistance variation is investigated under several different parameters of boundary condition of the third kind. It is found that thermal spreading resistance along motherboard bottom surface increases or decreases by the difference of boundary condition.

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Increase of power consumption in data centers due to the development of ICT technology has become a problem in recent years. Reducing the air conditioning power consumption is significant important for maintaining the function of data centers while decreasing the total power consumption. In this study, we developed a heat transfer module to remove the heat exhausted from a High-Powered Server Rack. The heat transfer module with multi-stage heat exchangers can transport more than 50% of the exhaust heat from servers generating 20 kW/rack.

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Flow soldering process with a simple model has been studied using CFD. A printed circuit board with through-hole components and with surface-mounted components covered with a mask is the object of this study. In this process, surface mounted components are first soldered and covered with the mask; then through-hole components without the mask are soldered by dipping the board into a solder bath. We investigate the solder flow in a narrow opening between the masks. Surface tension and contact angles are decided by comparison with experiments.

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The threshold energy release rate for stress corrosion cracking, G_<th>, of SiO_2 in humid atmosphere is analyzed based on the atomistic simulation model of water molecule adsorption on the surface of SiO_2. The analyzed results of environmental partial water vapor pressure dependence of G_<th> coincide well with the experimental results.

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Characteristic of nanowire is gradually attracting many researchers with potential applications of nano devices, nano sensors, solar sells and so on. This paper describes fabrication and evaluation of Cu nanowire surface fastener grown in porous aluminum. To fabricate nanowire surface fastener, at first anodic aluminum oxide (AAO) template are fabricated by two steps anodization method in 0.01 M, 0.1 M and 1.0 M sulfuric acid. Next, Cr and Au films were evaporated on the patterned side of Si wafer as a conductive working electrode. Nanowire surface fastener was formed via electrical deposition in copper sulfate aqueous solution. After etching in 3 M NaOH aqueous solution to remove porous aluminum, we obtained nanowire surface fastener on Si wafer perpendicular to its surface. High density Cu nanowires with average diameter of 20 nm were observed by scanning electron microscope. In order to understand the performances of Cu nanowire surface fastener, electrical and mechanical properties of them were studied in details.

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GaAs has characteristics which are a high-speed operation and low power consumption. So, GaAs is applied as a material of circuit elements and substrate of integrated circuit. When a devise is designed with a semiconductor material, electrical properties as carrier concentration, resistivity and mobility are important factors. A technique for accurately measuring those values is required. In this study, we attempted to evaluate resistivity and mobility of GaAs by microwave inspection method which can inspect a specimen with non-contact. The method can evaluate resistivity because amplitude of microwave reflected from a specimen is changed by conductivity of the specimen. In this paper, using the relationship of the electrical properties and Q factor, the electrical properties were evaluated. Linear relationships were observed in resistivity and Q factor obtained in the experiment. As the result, quantitative evaluation of resistivity and mobility with high precision were succeeded.

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In order to measure full 3D internal strain field of resin molding compound specimens, synchrotron computed tomography and laminography at SPring-8 were performed. Then the reconstructed images were applied to 3D digital image correlation method to compute internal strain field. The results showed that internal strains in resin molding compound could be visualized in this way.

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Shear fatigue tests of Sn-3.0Ag-0.5Cu solder joints were carried out by the combination of an advanced lap-joint specimen with high stiffness fixtures. This paper presents an evaluation of fatigue crack initiation lifetime of the joints under the condition of low strain rate followed by creep deformation. Consequently, an experimental relation between the inelastic strain range and the number of cycles corresponding to 20% load decrease were obtained.

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Engine control units or power control unit are key technologies for new vehicles like hybrid cars, electric cars and hydrogen-fuel cell vehicles. These power devices must be protected by plastic packages from circumstances. However, severe circumstances in engine rooms cause delaminations between components in the plastic packages. In this study, we evaluated the stress intensity factors of a corner and a small crack along the interface between molding resin and a substrate in the plastic package of a power devise. Stress intensity factors of a corner were useless because the order of stress singularities of a corner change with temperature and the combination of components. However, evaluated stress intensity factors of a crack on the interface can evaluate the strength of the interface between molding resin and a substrate reasonably.

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After briefly reviewing some preparation schemes of porous polymeric materials, polymer foaming methods which use supercritical carbon dioxide (CO_2) or nitrogen (N_2) as a physical blowing agent are brought into focus. Microcellular foams whose cell size is less than 10 μm and cell density is higher than 10^8 cm^<-3> are prepared by the method. Controllability of cell morphology in the foaming method is discussed. Several schemes of reducing the cell size to nanometer scale and producing nanocellular foam are introduced. The use of crystal nucleating agent as bubble nucleating agent is also introduced as a promising method for producing micro/nanocellular foam.

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The fibre space holder (FSH) method combines powder metallurgy and lost-foam casting and aims at the production of an ultra-thin novel material with micro-sized porous structures. Throughout the production process, a fabric is used as a spaceholder and coated with a mixture of metal powder (mostly stainless steel and copper, nickel) and water-soluble polymers. In the sintering process, the spaceholder is removed through by high temperature treatment to obtain the final porous metal sheet. This new material combines the advantages of both fabric and porous metal. With a large specific surface area, a minimum thickness of less than 30μm, a maximum porosity of over 95% and a strong liquid absorbency, it is predestined to be used in various application areas, the main ones being electrodes in hydrogen fuel cells and medical applications. With the purpose of adding additional features to the material, the metal sheet can also be coated with nano powder.

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Open-cell porous aluminum (Al) was fabricated by friction powder sintering (FPS) process without using external heat sources. In this process, powder mixture of Al powder and sodium chloride (NaCl) powder as spacer particle was used as starting material. The compacting and sintering of the mixture were conducted only by rotating tool plunged into a die and mixture. NaCl was removed by placing the sintered mixture in water. In this study, porous Al was fabricated using ADC6 powder, and pore structures of obtained porous Al were nondestructively observed by X-ray CT. In addition, compression properties of obtained porous Al were investigated.

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Porous materials are usually isotropic. If there is a porous material with spheroidal shape cell, the mechanical and physical properties in the different direction of this material should be different. In this study, compressive tests of spheroidal polymeric cellular structural material were performed. The compressive stress of this material in the direction of the major axis of cells is twice larger than that of the miner axis of cells in this material. Young's modulus of this material in the direction of major axis is also larger than that of the miner axis in this material. From the observations of the deformation of the specimen during compressive tests in the scanning electron microscope, deformation mechanisms were different in the different loading directions.

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Lotus-type porous metals with directional pores are fabricated through unidirectional solidification by adding hydrogen into the melt. Three solidification techniques are developed: a mold casting, a continuous zone melting and a continuous casting techniques. The last is the most superior with merit of controlling the solidification velocity. Hydrogen can be supplied into the melt by pressurized hydrogen or addition of hydrides. One of the prominent application of lotus metals is heat sinks. High cooling performance is possible by adopting lotus copper because of high heat transfer coefficients.

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The mechanical properties of low-density expanded polypropylene(EPP) are investigated by the newly designed testing machine. In order to prevent bucking, the shape of compression specimen are a cube which is formed by the adhesion of multi EPP sheets. The strain rate dependency of the flow stress was observed. Stress relaxation was observed in multi step displacement compression test. The strength of the compression specimen showed anisotropy, because of the influence of the adhesion layer.

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Porous aluminum is a lightweight material with high energy absorption properties. In this study, impact test of composite A1050 and ADC12 porous aluminum fabricated by friction stir processing (FSP) route was carried out. It was shown that composite porous aluminum was ductility deformation. From this result, it was shown that A1050 porous aluminum is effective to prevent the brittle fracture of ADC12 porous aluminum.

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Recently, porous metal materials attract attention. In comparison to general metal materials, porous ones have various characteristics. As an environmental friendly method of porous aluminum production, there is molding by chemical reaction between pure water and pure aluminum powder. However, it is difficult to control vacancy properties. Then, pure aluminum fiber is attracted. The purpose of this study is to control density of porous material formed by chemical reaction between pure aluminum fiber and pure water. Pure aluminum fiber is pressed in the cylindrical mold, pure water is poured into there, and it is kept at 40℃ for 48 hours by water bath. By chemical reaction, aluminum fiber is solidified. As a result, pure aluminum reacts with pure water and the surface of aluminum fiber was coated by layer of aluminum hydroxide. Therefore aluminum fiber was fixed, it is turn out to be able to make porous aluminum by using chemical reaction.

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We had developed titanium foam (Ti) by original slurry foaming method. In previous works, we had reported the cytocompatibility, corrosion resistance and mechanical properties of the Ti foam and multi-layered ones. In this work, we selected the data relating to coating application of the foam from the previous works and made an analysis of mechanical properties. The prepared Ti foam had chemical composition corresponding to grade 4 in ISO 5872-2 (Implants for surgery) and small surface pore diameters of 180, 320 and 500μm in average with porosity of 80-87%. In vitro cell penetration assay was performed for the foam with different pore diameters. The Ti foam of diameter 320μm showed the largest and stable cell penetration among the Ti foam tested. In compression test, the mechanical properties of a single and stacked foam samples were examined. The Young's modulus and yield strength were in the range of 1.3-3.8 GPa and 8-20 MPa respectively, which were comparable with those of human cancellous bone (0.2-3 GPa and 3-30 MPa respectively). Those properties were in good agreement with the calculation by Gibson-Ashby's equations. These results of the Ti foam make it a promising material in the field of coating for orthopedic implants.

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Porous aluminum (Al) was fabricated by a tool traversing friction powder sintering process. In this process, a mixture of Al powder and sodium chloride (NaCl) powder as spacer particles is starting materials. The powder mixture was places in a mold, compaction and sintering was conducted only by the traversing of a rotating tool as in friction stir welding. In this study, porous Al with NaCl volume fractions of 60%, 70% and 80% were fabricated by a tool traversing friction powder sintering process and a relationship between porosity and mechanical property was investigated. By X-ray computing tomography, it was found that the fabricated porous Al had uniform pore distribution. In a compression test, it was observed that the high porosity porous Al indicated low compression stress. Consequently, it was shown that mechanical property of porous Al can be controlled by NaCl mixing rate.

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The low elastic modulus titanium alloy used for implant has been investigated, and the conflicting problem of strength and porosity has been challenged. Manufacturing of porous material by capsule-free hot isostatic pressing (HIP) can be expected for simultaneous control of porosity and mechanical strength. In this study, commercial pure titanium powders were sieved below 150μm and 106μm, and the sieved powders were compacted by hydraulic hand operated pressing machine. Then, the compacts were sintered by electric furnace under atmospheric pressure argon gas at 823K, and finally capsule-free HIPed under high-pressure argon gas (150MPa) at 1523K. Results showed that the HIPed compacts maintained pores sufficiently, and the character was affected by compaction load. The aspect of pore forming was, however, considered to be different in the surface and the inside.

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Porous aluminum is a lightweight material with high energy absorption properties. In this study, ADC12 porous aluminum / A1050 dense aluminum plate sandwich panel was fabricated by friction stir processing route. Three-point bending test was carried out to observe the deformation behavior of fabricated sandwich panel. It was shown that crack firstly occurred in porous aluminum part, then spread to dense aluminum part.

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