Transcatheter closure via occlusion devices has been widely used for the treatment of atrial septal defect (ASD), which is the third most common congenital heart defect in children. Device embolization is one of the major complications of this method, which may require emergent surgeries. In this study, we constructed a finite element model of the ASD occlusion devices (Figulla® Flex II, FFII and Amplatzer® Septal Occluder, ASO) for the purpose of investigating the mechanical behavior of the devices under tensile tests and furtherly the risk of malposition, followed by experimental tests to evaluate the results. The geometry model of the ASD occlusion device was built by processing the photograph of the device via Photoshop, Illustrator, MATLAB and Abaqus, based on the geometrical characteristics of the device. The material (Nitinol) was assumed to be superelastic, and the material properties were obtained by tensile tests of Nitinol wires. The model was pulled in the finite element analysis using Abaqus/Explicit. Experimental tests were carried out under the same condition, and the load-displacement curves were studied to evaluate the results of the simulation, as well as to compare the risk of embolization of two types of devices.

Functional optical coherence tomography (fOCT) has been developed as a three-dimensional (3D) and micro-scale brain functional imaging technique. The brain functional signal obtained from fOCT is based on changes in OCT signal intensities before and after a given stimulation. However, it is difficult to accurately calculate the functional signals since the signals are usually contaminated with lots of physiological noises e.g. heartbeat and respiration. In this study, in order to remove such noises, we proposed a combination of fOCT and Fourier imaging, which uses periodic stimulation and extracts a component at the stimulus frequency in acquired OCT signals. The proposed method was applied to cat early visual cortex and visualized the first clear maps of 3D brain function by fOCT. The functional maps obtained by fOCT were compared with the neural response properties and showed statistically significant correlations (ρ_T = 0.0318, p = 1.29 x 10^-11). Therefore, the combination of fOCT and Fourier imaging is promising to improve detection accuracy of fOCT, suggesting the utility for clinical diagnosis of brain dysfunction.

The human middle ear is composed of tympanic membrane and 3 bones (ossicles). Ossicles are supported by ligaments and tendons. Ossicular fixation is caused by fixation of the ligaments and the tendons derived from aging or lesion. The tympanoplasty surgery is effective cure for conductive hearing loss caused by ossicular fixation. Although evaluating the mobility of the ossicles during the surgery is important, the assessment of ossicular mobility was usually made with palpation by surgeon and depends on the surgeon's sense. Fixation parts and degrees are different among patients, and identification of the fixed parts is difficult particularly in case of combined fixation. Therefore, the ossicular mobility of each pathology should be quantified for accurate assessment. In this study, compliance change caused by fixation of the ligaments was simulated using a finite-element model of human middle ear to investigate effective measuring procedure of ossicular mobility for diagnosis. Singular fixation cases and combined fixation cases were calculated. The fixation of the ligament was represented by increasing their stiffness. Compliances in Z-axial direction at each point of ossicles obtained from fixation cases were compared with the compliances obtained from intact model. The results suggest that measuring the difference between compliance at the malleus and the incus might helpful to distinguish between anterior malleal ligament fixation and posterior incudal ligament fixation. Also, measuring compliance at the stapes is considered to be necessary because stapedial annular ligament fixation most effects to ossicular mobility.

In the present study, the strain behavior of the native and the reconstructed ACLs in response to anterior drawer force was determined for assessment of the ACL reconstruction. Anterior drawer force up to 100 N was applied to native (n=10) and the reconstructed (n=5) knee joints at full extension, 30 and 60 degree of flexion using custom made 6-DOF robotic system. A novel three dimensional analysis, we call rotational stereo imaging method, was used for calculation of the strain distribution of both the ACLs. Result revealed that the tensile strains were larger in the ACL attachment area than in the mid-substance at full extension both the ACLs. In knee flexion, strains were decreased in the posterior fiber and increased in the anterior fibers in the native ACL. In contrast, strains were equally increased in the anterior and posterior fibers in the reconstructed ACL. In addition, averaged length change of the fibers was larger in the native ACL than in the reconstructed ACL. While native ACL attaches to the femoral and tibial bone surface through several tissue layers, reconstructed ACL attaches directly to the inner surface of those bone tunnels. Therefore, load transmission pattern maybe different between the native and reconstructed ACLs, which probably resulted in the difference of the deformation behavior between the native and reconstructed ACLs in knee flexion.

We propose a new model for tactile perception of the finger pad of a human based on the stick-slip vibration. It is known that a frequency of the stick-slip vibration to occur on the contact surface of two hard substances depends on the relative speed to each other, the load applied on the contact surface and the difference between the coefficients of static and kinetic friction. We suppose that similar dependence can be applied to the finger pad with a fingerprint. The validity of our model is shown from the both of an experiment and a numerical simulation. In the experiment, a rubber board with stripe and rectangular shapes is used instead of the fingerprint to get a relationship between the surface roughness and the relative speed, the load on the contact surface and the frequency of stick-slip vibration. As a result, it is shown that the stick-slip vibrations with the same frequency occur in a particular range of the relative speed V and the load W. In the numerical simulation, one-dimensional beam model corresponding to an elastic body with rectangular shapes is investigated in the case of acting only a horizontal shear force. It is shown that the frequency change of stick-slip vibration is remarkable in the range of a small value of V/W.

Cochlear microphonic (CM) is known to faithfully correspond to the frequency and level of sound pressure applied to the cochlea. If the CM is measured and compared before and after the treatment during an otologic surgery, the improvement of hearing of patients can be evaluated, and the risk of reoperation can be decreased. However, in some operations the sound transmission mechanism of the middle ear is temporarily disabled, and sound pressure cannot be applied to the cochlea with a speaker. In this study, a system for measuring the CM during surgery was constructed. The system consists of a vibration probe, electrodes, amplifier, and controller. The ossicles are vibrated by the vibration probe instead of sound from speaker, and the CM signals generated by the vibration are measured. The CM amplitude increased in proportion to the input voltage to the vibrator in the vibration probe as is the case with sound stimulation. This result suggests that the intraoperative assessment of improvement of hearing is possible by using the vibration probe.

Colles’ fracture is a common injury that tends to result in dorsal displacement of the bone fracture fragment of the distal radius. Most wrist fractures can be treated with closed reduction and wrist immobilization in a specific position to restore the displacement. However, the most effective position of wrist immobilization remains controversial. In this paper, we used a cadaveric and computational approach to reveal an effective position concerning pressure on a dorsal surface of the distal radius as a stability factor during wrist immobilization. Cadaver wrists containing a force sensor were prepared, and a numerical simulation model was constructed to determine the relationship between pressure on the distal radius and various wrist positions. The major contributing factors for putting pressure on the distal radius were the abductor pollicis longus and extensor pollicis brevis. The position that exerted a strong force on the distal radius was determined by considering the direction of the reaction force vector: pronation and ulnar deviation without flexion/dorsiflexion, with slight palmar flexion and with slight dorsiflexion. The cadaveric and computational method shown here is the first to identify the most effective position for wrist immobilization concerning the mechanical force on the dorsal surface of the distal radius. The optimal immobilization position in terms of contact force can be determined for each patient depending on the fracture type and specific patient physical characteristics by the constructed simulation system which is capable of changing parameters of the numerical model.

The three-dimensional tooth axis or longitudinal axis of tooth is an important as a morphological reference axis; however general definition of the tooth axis has not been established. In general, previous methods of calculating tooth alignment have relied on models cast from molds of patients' mouths, which have then been measured by methods such as touching the stylus of a 3D measurement device to feature points on teeth and using a 3D laser measuring device. In this study, we developed a global coordinate system based on maxillary and mandibular feature points from 3D reconstructions using in vivo cone-beam computed tomographic image data, devised a procedure for automatically calculating the tooth axis of the maxillary and mandibular front teeth and the absolute 3D position of the tooth alignment.

In the present study, the characteristics of surface oscillation of acoustic liposomes (ALs) in a standing sound field at 110 kHz has been investigated experimentally. The dependence of the bubble radius on the mode and the amplitude of surface oscillation has been analyzed. As the decrease in the bubble radius from 39.28 μm to 26.45 μm, the surface oscillation of the 5th mode to the 3rd mode were observed. It was found that there exists a radius where the amplitude of surface oscillation takes the maximum in each mode. Assuming that the surface oscillation of ALs is caused by the mechanism of parametric excitation by the surface tension model, the surface tension of ALs is estimated to be about 0.03 N/m.

This paper proposes a culture tissues regeneration system combining culture promotion and capsule destruction by shock wave, and describes the development of the system. In this system, shock wave are applied to microcapsules containing bubbles for DDS to simultaneously stimulate cells and destroy capsules. The capsule have an important role as a medium for cell culture in regenerative medicine. In this study, shock wave is generated in water using short-time laser with femtosecond as the purpose of stimulating cells. Particle motion around the focal point was observed by image processing. And the pressure at the focal area was also obtained by solving motion equation of particle. As a result, the pressure received by the particle at the position of 48.9μm from the focal point was 192Pa, and the pressure in the focal area was predicted to be 0.29MPa.

This paper reports that the effect of cumulative number of time of pulse discharge on the deburring for SUS burrs of micro order in the tip of medical implant by the underwater explosion loading induced by the pulse discharge into the burrs attached without and with microbubbles. The high repetition frequency of pulse discharge was set to be 10 PPS. The microbubble diameter of 40 μm was generated by the pressurization-bubbling method with the microbubble generator. The height distributions of the burrs and implant surface were measured by the 3-D digital microscope before and after the pulse discharge. The maximum height was decreased as the increased cumulative pulse discharge shot, and a part of burrs was disintegrated by the underwater explosion loading when the discharge shot was about 4000 without attaching microbubbles on the implant. The maximum height of burrs with attaching microbubbles subjected to the pulse discharge was more decreased than that without microbubble in the 4000 discharge shots. These results of this study suggested that the increase of cumulative discharge shot and the attaching microbubble on the burrs was useful to the promotion of deburring the remaining metal burrs of micro order in the implant.

It is known that the coefficient of friction between articular cartilages is extremely low. And although the structure and constituents of the joints are known, the mechanism of lowering the coefficient of friction is not known. We experimentally reproduce the joints using the articular cartilage tissue model and pseudo joint fluids, and verify the combined lubrication effect. As a method, a chondrocyte-agarose complex prepared by seeding chondrocytes isolated from bovine cartilage tissue on an agarose gel is cultured in a CO2 incubator, ECM are produced by chondrocytes during the culturing period, and accumulated in the agarose gel. The friction characteristics of the surface are evaluated under a slight load with simulatedly prepared synovial fluid as a lubricant. As a result, those with ECM were relatively lower in friction coefficient. However, problems such as lack of ECM and vertical loads not so stable are found.

The knee joint menisci play important roles in weight bearing, stress dispersion and stabilization. It is reported that the loss of its mechanical function due to injury and aging-related degeneration occasionally results in osteoarthritis (OA). Cartilage damage incident to knees suffering from OA is more severe on the femoral side than on the tibial side, probably due to differences in the tissue structure, frictional and mechanical properties between tibial and femoral sides of menisci. In the present study, medial meniscus from porcine knee was divided into three regions (anterior, middle and posterior) and coronal sections were examined histologically with hematoxylin-eosin staining. Then, porcine medial menisci explants were harvested from six locations including the femoral and tibial sides at three regions. Indentation tests were performed on the explants at a compression rates of 5, 30, and 100 μm/s. In addition, reciprocating friction tests were performed on the explants at a sliding speed of 5 mm/s. Histological examination indicated that the entire meniscus was surrounded by collagen-like fibril tissues and that the thickness of the tissues was 97.9±30.3 μm and 181±29.4 μm in femoral and tibial sides, respectively. Equivalent elastic modulus of the meniscus surface was significantly higher in tibial side than in femoral side at a high compression rate. In contrast, the coefficient of dynamic friction of the meniscus was smaller in tibial side than in femoral side. These results indicated that the surrounding tissue of the menisci influences in tibial side its frictional and mechanical properties.

On the articular cartilage surface, proteoglycan molecules protruding from cartilage surface form hydration layer. The hydration layer contributes to excellent lubrication property of articular cartilage, but its detailed mechanism has not been clarified yet. In this study, to elucidate the lubrication mechanism of the hydration layer, we investigated structural and lubrication properties of the hydration layer. Cartilage specimens were harvested in a cylindrical shape from the load-bearing area of the distal femur of immature porcine knee. In addition to intact cartilage samples, rubbed cartilage samples were prepared in which the hydration layer of the samples was removed by rubbing against a flat glass plate with a friction distance of 16 m or 60 m. Surface morphology of cartilage samples was observed by an amplitude-modulation atomic force microscope, and cross-sectional imaging of hydration layer was conducted using a frequency-modulation atomic force microscope. Friction test was performed for the cartilage samples against an alumina ceramic ball of 3 mm in diameter with a friction speed of 0.5, 1.0 and 5.0 mm/s. Surface morphology revealed that the hydration layer was removed with 60 m rubbed cartilage. Cross-sectional imaging revealed that the hydration layer with a thickness of approximately 6 μm was confirmed on intact cartilage surface. Coefficient of dynamic friction of intact cartilage was lower than that of 60 m rubbed cartilage, and coefficient of dynamic friction of intact cartilage tended to decrease with increasing friction speed. These findings suggested that the hydration layer contributes to improvement of lubrication properties of articular cartilage.

To gain the understanding of in vivo friction and wear behavior of implanted joint prosthesis, we carried out the pin on plate reciprocating sliding tests. We applied for CoCrMo as the pin specimen, UHMWPE as the plate specimen and protein-free PBS solutions containing Albumin and y-globulin (proteins), HA and/or DPPC as test lubricants. After sliding tests, we analyzed plate surfaces by FT-IR. And each lubricant was measured viscosity. As the results, proteins rapidly increased Coefficient of Friction (CoF) and we found IR spectrum deriving from proteins by FT-IR. So Protein increased CoF by making adsorption films. HA decreased CoF and increased viscosity. So HA may have the effect to make hydrodynamic lubrication film. DPPC increased CoF gradually. And only DPPC sample was found hard wear marks. So DPPC may make UHMWPE plasticization and cause abrasive wear.

This paper presents a suitable technological solution to a problem of spray painting of high reflective paint. Recently, high reflective paint receives attention to reduce the temperature raise on the outside of large containers or storage tanks, and to maintain the quality of the material stored inside them. On the other hand, to coat the tall and large storage tank with high reflective paint often place the skilled workers of painting in a dangerous situation. For the skilled workers of painting who conduct washing with high-pressured water and/or spray painting outside the tank, the problem is height place working which is difficult to keep balance for sudden. This paper is aimed to solve the problem of height place working in spray painting outside of storage tanks by replacing a skilled worker with water washing and/or spray painting robot which can be controlled by the remote control from an operator on the ground. The most important factors for considering the suitable kinds of robot with respect to its application are described in this study. The driving mechanism and controller of the developed robot are explained in the present work. The ideas for developing the robot with desired working abilities can be followed according to this study.

Shaft seals are widely used in many mechanical parts. However, their operating conditions are limited. Especially, there are few shaft seals which can operate with changing the rotational direction of rotating shaft or with in a range of low to high shaft speed or under a high-pressurized water environment. Furthermore, a design of the shaft seal, which is different from a conventional mechanism are needed for realizing the shaft seal which shows a low frictional torque and amount of leakage. The seal ring which operated in boundary lubrication was proposed to enable it to be used under those severe conditions. The seal ring was made of a hydrophilic and high molecular material; polyvinyl formal (PVF). This seal ring had a low elastic modulus, so that it was clarified to deform easily under the high-pressurized water environment. In this report, a new type of shaft seal was development by changing an approach in use of the seal ring in order to avoid such as the deformation. The seal ring of the new shaft seal was pressed to the ceramics ring fixed with a mechanical body, and the shaft seal prevented water leakage between them. The experimental results indicated that the properties of ceramics ring had an influence on the durability of the seal ring.

To provide rotating machineries with waterproof structures, sealing systems like shaft seals are essential. Although many products are available, few materials are designed to be operated under low speed and high water pressure conditions. In previous studies, new sealing systems with hydrophilic seal lips were developed and showed great sealing performance under the conditions that conventional shaft seals couldn’t sustain its performance. In this reports, fiber reinforcement was introduced to enhance the sealing function or expand its operating area. Two types of cellulose fibers were used as reinforcements. Sealing performance tests were conducted under multi-speed condition and constant pressure of 0.5 MPa. As a result, it was suggested that cellulose nano fiber was a good candidate for the reinforcement of PVF seal lips.

The accumulation of snow on a runway is a problem for operation of airplane. Therefore, it is necessary to estimate the friction coefficient between a tire and a snowy runway for airplane landing. This study investigates the state of snow between the tire and the stainless steel plate and estimate the influence of the snow on friction coefficient. The investigation uses electrical conductivity to observe degree of separation between the tire and the stainless steel plate. The frictional force and normal load were measured using a 6-axis dynamic sensation sensor in order to calculate the friction coefficient. This results show that the microscopic separation due to interposition of snow can be observed. In addition, It was confirmed that the higher the density and the thickness of snow (the higher degree of separation), the lower the coefficient of friction, and the lower the density and the thickness, the higher the friction coefficient. Hence, the friction mode is broadly divided into two modes, high friction mode and low friction mode.

In Tissue Engineering developed by Langer and Vacanti, it is known that lost tissues and organs can be regenerated artificially. Tissue engineering requires three elements, i.e., cell, growth factor, and biological material for cell scaffold, and these elements interact with each other. Thereby, the original regeneration ability of organisms can be enhanced. The surface properties have been considered to affect to material and cell interaction because a cell contacts directly with the surface of a biomaterial. Therefore, in this study, the change of the surface state of the material by plasma surface treatment and the influence on the cell adhesiveness were investigated. Since PET has been employed as cell scaffold, its adhesiveness to a PET plate in vortex flow was investigated. Although the surface of PET temporarily became hydrophilic by the plasma surface treatment, the contact angle changed with time and reached to the same value as that of the control material after about 9 days. The surface chemistry by XPS measurement was found that the surface was oxidized. In this study, the decrease in the contact angle and the increase in the surface oxygen content by the plasma treatment were found to affect to the cell adhesiveness to PET plate.

In this study, osteoclasts are cultured on the substrates with the different molecular weight, elastic modulus and material type, in order to investigate the influence of the substrate material type and properties on the osteoclast metabolic and desorption behavior. Here, PCL and chitosan were used as materials for substrates to culture osteoclasts. The PCL substrates ware prepared by changing the cooling rate to change the degree of crystallinity and subsequent elastic modulus. The Chitosan substrates with different elastic modulus were prepared by changing the degree of crosslinking. Osteoclasts were then cultured on the prepared substrate for 48 hours. The substrate mechanical properties were evaluated by tensile tests. As a result, neither the PCL substrate nor the chitosan substrate showed the marked difference in the mechanical properties of the substrate due to the metabolic behavior of osteoclasts and hydrolysis. It is considered that the incubation period of osteoclasts as an important factor for the interaction between the metabolic behavior of osteoclasts and the mechanical properties of the substrate was short.

Intramedullary nail fixation is one of the useful treatments for subtrochanteric fracture. The intramedullary nail used is selected from two types, long type and short type. In many cases, long intramedullary nail is applied to treatment of subtrochanteric fractures. However, there is discussion on application of long intramedullary nail from the viewpoint of minimally invasive. A middle intramedullary nail, which has an intermediate length between long type and short type, was developed. It is essential to conduct biomechanical investigations of the intramedullary nail systems subjected to various loads. The aim of this study was to investigate the influence of length of intramedullary nail for subtrochanteric fracture models with Seinsheimer classification IIB. Three types of intramedullary nail were considered: long type, middle type, and short type. Subtrochanteric fracture finite element (FE) models, which included the femoral fracture of Seinsheimer classification IIB and the intramedullary nail system, were developed. A 1-mm-thick callus layer was set in the gap between bone fragments of the femur. As a result of FE analysis, the effectiveness of middle intramedullary nail was indicated from the viewpoint of bone union and invasiveness.

Commercially pure (CP) titanium with a bimodal harmonic structure, which is defined as coarse grained regions surrounded by a network of fine grains, was fabricated by consolidating mechanically milled powders to improve both strength and ductility. In this study, thermo-mechanical processing was performed for the CP titanium with a bimodal harmonic structure to improve the fatigue properties. In order to determine the fatigue properties of thermo-mechanical processed CP titanium with harmonic structure, four-point bending fatigue tests were conducted at a stress ratio of 0.1 under ambient environment. The fracture surfaces and the specimen surfaces were analyzed by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) to identify the mechanisms of small fatigue crack initiation and propagation on the basis of fractography and crystallography. Thermo-mechanical processed CP titanium with harmonic structure had longer fatigue life than CP titanium with harmonic structure. This was attributed to the increase of the fatigue crack initiation resistance. On the other hand, the small crack growth rate behavior in thermo-mechanical processed CP titanium was almost the same as CP titanium with harmonic structure. Consequently, the small fatigue crack initiation and propagation properties of thermo-mechanical processed CP titanium with harmonic structure were clarified.

Titanium alloys is widely used as biomedical implant materials due to its high strength and biocompatibility. However, poor wear resistance has prohibited its application as bearing materials for artificial joints. In order to improve the wear resistance of titanium alloys, much research has been done on surface modification of titanium. Plasma discharge modification (PDM) is one of the promising surface modification methods of titanium. In this study, wear and corrosion resistance of PDM treated titanium, TiC processing and Si processing, was evaluated. The result of ball on disk wear test showed that PDM greatly improves the wear resistance of titanium. This is attributed to the hard TiC layer formed by PDM both on TiC processing and Si processing. The result of anodic polarization tests revealed that the PDM layer shows equal or superior passive current density compared to titanium substrate. However, the pitting potential decreased compared to titanium substrate. Observation of the tested samples show that the corrosion started from the dimple and the interface of the PDM shots created during modification. Therefore, the early pitting potential may be caused by the galvanic coupling of the substrate and the PDM layer at the dimple and PDM shot interface.