Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.surfcoat.2022.128238

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.triboint.2021.107399

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.surfcoat.2021.127899

Language：English   Publishing type：Research paper (scientific journal)  

This article aims to investigate the influence of reinforcing graphene oxide (GO) and graphite flakes (GF) fillers into ultrahigh molecular weight polyethylene (UHMWPE) for orthopedic application. These fillers were expected to physically bond to UHMWPE, thus can enhance the subsurface strength, improving the wear behavior of the composites. UHMWPE/GO and UHMWPE/GF composites were prepared at 0.1 and 1.0 wt% by melt-blending, followed by a compression molding technique. A multidirectional pin-on-disc wear test was performed to simulate the kinematic of hip application. Whilst getting exposed in the artificial in-vivo lubricant bath (30 v/v% diluted bovine serum). Following this, the wear mechanism fostered by each filler (GO and GF) was determined by wear features obtained from the optical microscope and scanning electron microscope (SEM). The crystallinity degree and crystal defect were assessed using x-ray diffraction (XRD). The mechanical properties of fabricated composites were evaluated by using a universal testing machine and Vickers microhardness. We found that UHMWPE/GO has the lowest specific wear rate due to the improved subsurface strength, as the reduction of a weak adhesive point was observed on the worn surface. Meanwhile, higher GF content (1 wt%) in UHMWPE displayed a lower specific wear rate than neat UHMWPE after completing the 10 km sliding distance attributed to the filler resurfaced, responsible for providing a strong resistance of the shear stress applied upon sliding with the metal counterface. Interestingly, the hardness and tensile strength for both UHMWPE/GO and UHMWPE/GF increased, although the crystallinity percentage was declining compared to neat UHMWPE.

DOI： 10.1002/pat.5428

Language：English   Publishing type：Research paper (scientific journal)  

Single-filler polytetrafluoroethylene (PTFE) composites with different filler materials are prepared and their tribological characteristics are evaluated in gaseous hydrogen to investigate the tribological function of each filler material. The results indicated that glass fibre caused severe abrasion on the cast iron sliding counterface and hence increased wear in both the composite and counterface in hydrogen. The friction and wear characteristics of polyphenylene sulphide-filled PTFE in hydrogen are similar to those in ambient air because it formed a PTFE-based transfer film on the counterface regardless of the surrounding atmosphere. On the other hand, carbon fibre-filled PTFE indicates excellent low friction and low wear in hydrogen. In this case, both the composite surface and sliding counterface are covered with carbon-rich tribofilms.

DOI： 10.1016/j.triboint.2021.106884

Repository Public URL： https://hdl.handle.net/2324/7162265

Language：English   Publishing type：Research paper (scientific journal)  

In this study, the reciprocating pin-on-plate sliding test was conducted between ultra-high molecular weight polyethylene (UHMWPE) and CoCrMo alloy with test lubricants containing representative synovial fluid constituents, such as proteins, hyaluronic acid, and phospholipids, to understand their effects on the in vivo friction and wear characteristics of implanted joint prostheses. To explore some details of the friction and wear process, the wear track remaining on the UHMWPE plate specimens was morphologically analyzed by laser microscopy and chemically analyzed by Fourier transform infrared (FTIR) spectroscopy. The influence of each constituent on the rheological properties of the test lubricant was also evaluated using a rotational rheometer. We observed that proteins had a definitive impact on the friction and wear process; proteins adsorbed on the UHMWPE surface and increased friction and wear by changing the predominant friction and wear mechanism from abrasive to adhesive. Phospholipids also increased friction while hyaluronic acid decreased friction by increasing the viscosity of the lubricants and enhancing the fluid dynamic effect. However, when phospholipids and hyaluronic acid were mixed with proteins, they enhanced the entrainment of the protein molecules into the contact area and increased the wear of UHMWPE.

DOI： https://doi.org/10.2474/trol.15.283

Language：Japanese   Publishing type：Research paper (scientific journal)  

Mechanical design assessment of zirconia abutment supported on titanium base

Language：English   Publishing type：Research paper (scientific journal)  

It was reported in several studies that friction and wear of joint prosthesis are apparently influenced by the proteins contained in the synovial fluid. However, detailed mechanisms of these tribological processes have not been clarified yet. The present study aims on the effect of adsorbed protein film on frictional behaviour of metal/polyethylene contact pair. Reciprocating pin-on-plate test was conducted, while the CoCrMo pin was sliding against UHMWPE plate. The contact was lubricated by various solutions of albumin and γ-globulin solved in PBS. After the friction test, the thickness of adsorbed film was evaluated using spectroscopic ellipsometry. Structure of the adsorbed proteins was later examined by FT-IR. The results showed that at low sliding speed equal to 10 mm/s, there was a linear correlation between the friction coefficient and the thickness of the adsorbed protein film. An increase of friction was thus accompanied by the evolution of protein film. In that case, both proteins undergone substantial conformational changes, losing their original structure. On the contrary, proteins could sustain their secondary structure to some extent at higher sliding speed (50 mm/s), when different behaviour of the both proteins could be observed. This phenomenon was attributed to different structure of albumin and γ-globulin in its native state. It might be concluded that friction coefficient of metal-on-polyethylene joint prosthesis is influenced by protein content, as well as kinematic conditions, since the sliding conditions have a certain effect on both the adsorbed film formation and structure of the adsorbed molecules.

DOI： 10.1016/j.biotri.2017.03.003

Language：English   Publishing type：Research paper (other academic)  

Mechanical stresses exerted in articular cartilage during daily joint movements can stimulate the metabolism of chondrocytes in cartilage. Upregulative effects of mechanical stimuli on extracellular matrix (ECM) biosynthesis of chondrocytes have been utilized in the cartilage tissue for regenerative tissue engineering. However, dynamic functionalities of these regenerated cartilages were lacked compared with the natural arthrodial cartilage. Natural synovial joint surfaces are contacting and sliding each other. As a result, the loading condition applied to the cartilage tissue is not simple. Under the contact between surfaces, non-uniform stress distribution is exerted in the cartilage tissue. The shear stress at contact area is highly depended on the distance from the surface. Moreover, the surface region is exposed to larger shear stress compared with the deep region. We hypothesized that high stress in surface region may stimulate chondrocytes selectively and establish anisotropic structure in elaborated tissue. In this study, the relative motion between cartilage surfaces in a synovial joint is simulated by the rolling-sliding motion of the roller on the cultured chondrocyte-agarose construct. Then, we investigated effects on the ECM distribution and morphology of regenerated cartilage tissue.

DOI： 10.1109/MHS.2016.7824183

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.diamond.2015.11.011

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2474/trol.10.404

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.triboint.2014.12.011

Language：English   Publishing type：Research paper (scientific journal)  

To develop a novel biotribological material for artificial cartilage implant with a lubricity supplement of the joint surface, we focused on two
types of poly(vinyl alcohol) (PVA) hydrogel: repeated freeze–thawing (PVA-FT) and cast-drying (PVA-CD) gels. Here we observed the
morphology of wear particles generated during a reciprocating wear test and assessed macrophage immune responses by applying hydrogel wear
particles. As a result, PVA-CD had a significantly lower total amount of wear than did PVA-FT. The size distributions of PVA-FT and -CD wear
particles were similar. Most of the particles were nanoparticles up to approximately 50 nm in diameter. Considering the particle volume
distribution, there were very few micron- and submicron-sized wear particles around 1 μm in diameter. In SEM observations of dried PVA wear
particles, both distributions of wear particles of PVA-FT and -CD were similar. Micron-sized wear particles were chiefly formed by close packing
of 20- to 50-nm-sized particles. Biochemical and immunological evaluations revealed no cytotoxic effects of wear particles on macrophages.
Cytokine synthesis of both wear particle-stimulated groups was significantly lower than that of the lipopolysaccharide-stimulated positive control.
Therefore, it is suggested that PVA wear particles do not affect the macrophage immune response.

DOI： 10.1016/j.bsbt.2015.02.003

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.bbrc.2012.07.019

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.triboint.2011.03.016

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Influence of phospholipid bilayer on frictional behavior of artificial articular cartilage material

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Influence of synovia constituents on frictional behavior of artificial cartilage material and formation of boundary lubricating film

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Tribology for Functional Tissue Engineering of Articular Cartilage

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Influence of protein and lipid concentration of the test lubricant on the wear of ultra high molecular weight polyethylene

Language：English   Publishing type：Research paper (international conference proceedings)  

Effects of Hydrogen Atmosphere on Wear Behavior of PTFE Sliding Against Austenitic Stainless Steel

Language：English   Publishing type：Research paper (international conference proceedings)  

Accelerated Wear of UHMWPE for Joint Prosthesis in Physiological Solutions Containing Protein and Lipid

Language：English   Publishing type：Research paper (international conference proceedings)  

Cyclic Loading Test of Dental Implant with Mastication Simulator

Language：English   Publishing type：Research paper (international conference proceedings)  

Experimental Characterization of Regenerated Cartilage Model Cultured under Cyclic Compression

Language：Japanese   Publishing type：Research paper (scientific journal)  

The Effect of the Mixing Ratio on the Temporary Cement Retention Force and Seating Discrepancy of Cement-retained Implant Superstructures

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1299/jsmec.47.1049

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1023/B:ABME.0000030261.38396.c0

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1246/bcsj.20210323

Language：English   Publishing type：Research paper (scientific journal)  

In this study, the adhesion‐detachment behaviour of a gecko‐inspired adhesive pad was investigated to understand the on/off switching mechanisms of adhesion in gecko feet. A macroscopic spatula model was fabricated using silicone rubber, and adhesion tests combining lateral sliding and vertical debonding were conducted. It was observed that the contact state and the adhesion force of the pad vary considerably with the direction of lateral sliding prior to debonding, and that the pad achieves adhesion during debonding even when it loses contact due to excess lateral sliding. These results explain the mech- anisms behind the on/off switching and stable adhesion of gecko feet, and suggest the possibility of developing new‐generation adhesives capable of switchable adhesion.

DOI： 10.1049/bsb2.12003

Language：English   Publishing type：Research paper (scientific journal)  

Various hydrogels have been developed to use as artificial cartilage. Poly(vinyl alcohol) (PVA) hydrogel cross- linked by hydrogen bonds is biocompatible and has similar properties to natural articular cartilage. For clin- ical use as artificial cartilage, superior tribological performance with low friction and minimal wear are required. In our previous study, three kinds of preparation methods for PVA hydrogels with high water content, i.e., the repeated freeze-thawing (FT) method, the cast-drying (CD) method and the layered hybrid method composed of FT and CD layers were applied. As hybrid gel specimens, (CD on FT) and (FT on CD) gels were prepared. The comparison between experiment and biphasic finite element analysis showed that the frictional behaviors of these PVA hydrogels at slow speed are controlled by their biphasic lubrication mechanism. After that, it was found that the biphasic properties of FT gel with heterogeneous network structure was largely changed after immersion in water for more than 6 years. In this paper, the influence of changes in permeability with aging of FT gel on friction and biphasic behaviors of PVA hydrogels was evaluated by biphasic finite element analysis. As aged FT specimens with lower permeability, four kinds of aged FT specimens with different elastic properties were evaluated. As a result, it is suggested that frictional behavior of PVA FT gels with aging can be improved by lowering of permeability in aged FT gel. Furthermore, it is expected that hybrid gel as CD on aged FT with appropriate elastic modulus can sustain superior low friction.

DOI： 10.1016/j.biotri.2021.100178

Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this study was to investigate the effects of implant position and loading position on biomechanical behaviors using implant-supported removable partial denture (ISRPD) models in a simulated Kennedy class II partially edentulous mandible. Three types of Kennedy class II mandibular acrylic resin models (a conventional RPD without support by an implant—CRPD; models with an implant placed at first molar (#46)—MP-ISRPD— and second molar (#47)—DP-ISRPD) were used to measure vertical displacement of the RPD, mesio-distal displacement of the abutment tooth, and bending moment of the abutment tooth and implant under one-point loading. The variables at three respective loading points (#45, #46 and #47) were compared statistically. Vertical displacement was suppressed in ISRPDs compared to the CRPD, and significant effects were identified under loading at the implant position. The largest meiso-distal displacement was observed in MP-ISRPD under #47 loading. Bending moments of the abutment tooth and implant were significantly higher in MP-ISRPD than in DP-ISPRD. In MP-ISRPD, a higher bending moment of the abutment tooth under #45 and #47 loading was detected, although the bending moment in DP-ISRPD was almost zero. The results of this study suggested that MP-ISRPD shows the specific biomechanical behaviors, although DP-ISRPD might provide biomechanical benefits under all one-point loading conditions.

DOI： 10.3390/ma14092145

Language：English   Publishing type：Research paper (scientific journal)  

The attrition of enamel when opposed by ceramics is of great concern. The purpose of this study was to evaluate enamel wear against high translucent zirconia Zr, lithium disilicate LD, gold Au, and enamel E with different surface and contact conditions. The materials were divided into two groups: Polished and ground n=8 each. Two-body wear tests were performed against human enamel with vertical and horizontal, horizontal, and vertical repetitive movements as experiments 1 to 3 respectively. The surface roughness of all materials except Zr changed throughout the experiments. In experiment 1, Zr and Au showed less antagonist wear when polished than when ground. In experiment 2, polished groups showed less antagonist wear than ground groups in all materials. In experiment 3, Zr and LD exerted greater antagonist wear than E, regardless of Ra. These findings confirm the importance of polishing and occlusal adjustment of zirconia.

DOI： 10.4012/dmj.2020-190

Language：English   Publishing type：Research paper (scientific journal)  

We perform friction experiments between a compliant gel and a rigid cylinder at sliding velocities comparable to the Rayleigh wave or secondary wave velocity of the gel. We find that, when the sliding velocity exceeds the wave velocities, the contact state transitions from Hertzian like to flat punch like, resulting in the breakdown of the lubricating oil film and the abrupt increase in the friction coefficient. We succeed in deriving theoretical solutions for the contact pressure distributions and the deformation profiles in the presence of friction, which are consistent with our experimental observations.

DOI： 10.1103/PhysRevLett.124.238001

Language：English   Publishing type：Research paper (scientific journal)  

The toughening of sparse elastic networks, such as hydrogels, foams, or meshes against fracture is one of the most important problems in materials science. However, the principles of toughening have not yet been established despite urgent engineering requirements and several efforts made by materials scientists. Here we address the above-mentioned problem by focusing on the topology of a network. We perform fracture experiments for two-dimensional periodic lattices fabricated from rubber strings and connecters with well-defined topological structures. We find that systematic increase in the largest coordination number while
maintaining the average coordination number (¼ 4) as constant leads to significant improvement in toughness. We reproduce the observed toughening behavior through numerical simulations and confirm that the stress concentration in the vicinity of a crack tip can be controlled by the topology of the network.
This provides a new strategy for creating tough sparse elastic networks, especially hydrogels.

Language：English   Publishing type：Research paper (scientific journal)  

Hip joint replacements represent the most effective way of treatment for patients suffering from joint diseases. Despite the rapid improvement of implant materials over the last few decades, limited longevity associated with wear-related complications persists as the main drawback. Therefore, improved tribological performance is required in order to extend the service life of replacements. The effect of surface texturing of ultra-high molecular weight polyethylene (UHMWPE) acetabular cup was investigated in the present study. Unique tilling method was utilized for manufacturing the dimples with controlled diameter and depths on the contact surface of the cup. The experiments with four commercial femoral components and two model lubricants were realized. The main attention was paid to a coefficient of friction considering the differences between the original and the dimpled cups. Results showed remarkable lowering of friction, in general. Focusing on the simulated human synovial fluid, friction was reduced by 40% (alumina ceramic), 38.8% (zirconia toughened ceramic), 25.5% (metal), and 9.9% (oxinium). In addition, the dimples helped to keep the friction stable without fluctuations. To conclude, the paper brings a new insight into frictional behaviour of the hip replacements during running-in phase which is essential for overall implant lifespan. It is believed that proper surface texturing may rapidly improve the life quality of millions of patients and may lead to considerable financial savings.

DOI： 10.1007/s40544-019-0351-x

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1049/bsbt.2018.0031

Language：Japanese   Publishing type：Research paper (scientific journal)  

DOI： 10.3390/gels4020053

Language：English  

DOI： 10.1142/9789813227798_0003

Language：English   Publishing type：Research paper (scientific journal)  

Zirconia exhibits good tissue compatibility and nontoxicity, making it a widely used esthetic replacement material for implant abutments. To avoid abutment-fracture, the parts composed of zirconia with a bonded metal component connected to the implant can be used. The purpose of this study was to design titanium and zirconia components with high fracture resistance at the zirconia component’s edge line. Three edge line designs of the titanium base and zirconia sleeve were made: chamfer, shoulder, and back-taper. To assess the strength of the abutment design, static loads were applied vertically and 30 degrees from the vertical axis. A test of tensile strength was also performed after chewing simulation. Conventional zirconia components mounted on a chamfer-type titanium base showed significantly lower fracture resistance than shoulder and back-taper types. This study suggests that to improve the durability of zirconia abutments with a titanium base, a back-tapered edge design is recommended.

DOI： 10.4012/dmj.2017-022

Language：English   Publishing type：Research paper (scientific journal)  

The superior tribological performance in natural synovial joints with low friction and minimal wear appears to be actualized by not single lubrication mode but the synergistic combination of various modes from the fluid film lubrication to boundary lubrication corresponding to the severity of rubbing conditions. We have conducted the biphasic finite element analysis and some experimental studies for articular cartilage to elucidate this ingenious lubrication mechanism from the viewpoint of the adaptive multimode lubrication mechanism. In this paper, the effectiveness of different lubrication modes such as biphasic, boundary, gel-film and hydration lubrication particularly at low speed conditions is discussed.

DOI： 10.1016/j.triboint.2016.12.052

Language：English   Publishing type：Research paper (scientific journal)  

With recent progress of material technologies, the wear resistance of ultra-high molecular weight polyethylene for total joint prostheses has been improved, but under severe conditions friction and wear problems have not yet been completely solved. Therefore, the application of artificial hydrogel cartilage with similar properties to natural articular cartilage is expected to solve the friction and wear problems by improvement of lubrication mechanism with superior tribological functions. In this study, reciprocating tests of four kinds of poly(vinyl alcohol) hydrogels were carried out and the biphasic finite element analysis was conducted. As artificial cartilage specimens, four kinds of poly(vinyl alcohol) hydrogels were prepared using the repeated freeze-thawing (FT) method, the cast-drying (CD) method and the hybrid method with different layered structure as FT on CD or CD on FT. In reciprocating test of ellipsoidal poly(vinyl alcohol) hydrogel specimen against flat glass plate in saline solution, four kinds of hydrogels exhibited very different frictional levels as hybrid (CD on FT) < CD < FT < hybrid (FT on CD). It is noticed that hybrid (CD on FT) gel maintained extremely low friction and showed minimal wear. The effectiveness of biphasic lubrication was evaluated by biphasic finite element analysis. The importance of the load support by fluid phase at early stage and the surface lubricity after lowering of interstitial fluid pressure in poly(vinyl alcohol) hybrid (CD on FT) gel are discussed by comparison of experiment and finite element analysis.

DOI： 10.1177/1350650117712881

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.eml.2016.09.008

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.jmbbm.2016.04.004

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.2474/trol.11.320

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1177/0954411915611160

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1016/j.triboint.2014.12.013

Language：English   Publishing type：Research paper (scientific journal)  

The purpose of this study is to estimate material properties of articular cartilage by curve fitting method using finite element (FE) analysis. While various material tests have been conducted to predict the behavior of articular cartilage, one of the recent interests was the accurate estimation of material properties under physiological and dynamic condition. In this study, cylindrical indentation was experimentally conducted in high compressive amount and high compression rate in considering the physiological condition. Each single specimen was sequentially exposed to compressive tests at definite deflection with different compressive amount and different compression rates and compressive creep test. The time-dependent compressive force given by a precise compression tester was utilized for estimation of material properties by curve fitting method with FE analysis. Five typical material properties, which represented total apparent Young's modulus, strain dependent permeability and fibril reinforcement by collagen network, were selected for the estimation process with depth-dependency of Young's modulus. In the curve fitting processes by FE analysis, each material property had specific roles on reproducing experimental time-dependent reactional force. A single material property set estimated in this study successfully reproduced the four different experimental time-dependent behaviors.

DOI： 10.1299/jbse.15-00228

Language：English   Publishing type：Research paper (scientific journal)  

The protein film adsorbed on joint prosthesis material affects tribological property. It is expected that optimum protein film structure could improve friction and wear of joint prosthesis materials. Therefore, it is important to understand and to clarify the effect of protein film on tribological property. In the rubbing combination of ultra-high molecular weight polyethylene (UHMWPE) and CoCrMo alloy, the adsorption behavior of bovine serum albumin (BSA) and its effect on frictional property during friction were investigated by using electrochemical method. Friction force and electric potential were measured under open circuit potential (OCP) condition, but friction force and electric current were measured under -0.2 V applied potential condition. Under OCP condition, adsorbed BSA was peeled off at first rubbing, after that BSA re-adsorbed on surface under shear force condition. BSA adsorbed film reconstructed by shear force was sustained during rubbing. It is considered that the conformation of adsorbed BSA under shear stress was changed from that of static adsorption, because readsorbed BSA molecule did not show exfoliation from metal surface, which means that adsorption strength was increased from static adsorption. Under applied potential condition where wear performance of BSA film is expected to be evaluated, BSA showed the desorption at first rubbing, and gradual decrease in desorption amount. Therefore, it is confirmed that BSA film on metal surface under rubbing condition is reconstructed during rubbing. The adsorbed film formed during rubbing is stable and has an optimally-adapted structure for shear force and can sustain its property during rubbing.

DOI： 10.2474/trol.10.183

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1177/1350650114530273

Language：English   Publishing type：Research paper (scientific journal)  

In this study, the influence of phospholipid and protein constituents on friction and wear behavior of artificial hydrogel cartilage was investigated. A sliding pair of an ellipsoidal specimen of poly (vinyl alcohol) (PVA) hydrogel and a flat specimen of PVA hydrogel was evaluated in simplified reciprocating friction test. Dipalmitoylphosphatidylcholine (DPPC) was selected as a phospholipid constituent and was dispersed in saline as liposome. Fluorescent-labeled albumin and γ-globulin were used as protein constituents in lubricants at concentration of 0.7 wt%. After reciprocating friction test, the boundary film formed on the surface of PVA hydrogel and the worn surface of PVA hydrogel were observed by using fluorescent microscope and confocal laser scanning microscope, respectively. When only albumin or γ-globulin was added to lubricant, adhesive wear pattern was frequently observed and large breaking-offof surface structure of PVA hydrogel occurred. Lubricants that contain both proteins and 0.01wt% DPPC showed reduction of friction and suppression of large breaking-offof surface structure of PVA hydrogel. Meanwhile, under coexistence of protein and 0.02wt% DPPC, friction increased compared to that for lubricants that contain 0.01wt% DPPC and the adhesive wear patterns became obvious. Therefore, both the concentration and the relative ratio of proteins to phospholipids are important factors to function adequately as excellent boundary lubricant for PVA hydrogel.

DOI： 10.1299/jbse.8.257

Language：English   Publishing type：Research paper (scientific journal)  

The extremely low friction and minimal wear in natural synovial joints appear to be established by effective lubrication mechanisms based on appropriate combination of articular cartilage and synovial fluid. The complex structure of cartilage composed of collagen and proteoglycan with high water content contributes to high load-carrying capacity as biphasic materials and the various constituents of synovial fluid play important roles in various lubrication mechanisms. However, the detailed differences in functions of the intact and damaged cartilage tissues, and the interaction or synergistic action of synovia constituents with articular cartilage have not yet been clarified. In this study, to examine the roles of synovia constituents and the importance of cartilage surface conditions, the changes in friction were observed in the reciprocating tests of intact and damaged articular cartilage specimens against glass plate lubricated with lubricants containing phospholipid, protein and/or hyaluronic acid as main constituents in synovial fluid. The effectiveness of lubricant constituents and the influence of cartilage surface conditions on friction are discussed. In addition, the protectiveness by synovia constituents for intact articular cartilage surfaces is evaluated.

DOI： 10.1007/s40544-013-0010-6

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/j.1600-0501.2011.02305.x

Language：English  

This chapter discusses wear phenomena of ultra-high molecular weight polyethylene (UHMWPE) in artificial joints. The importance of wear in artificial joints, lubrication modes in artificial joints as UHMWPE-on-hard and improving methods for wear reduction of UHMWPE are reviewed. Wear phenomena of UHMWPE artificial knee joints are discussed with reference to the wear characteristics of retrieved artificial knee joints, together with an experimental study on the delamination mechanism of UHMWPE, macroscopic contact analysis between the femoral component and tibial insert, and microscopic contact analysis between surface asperities and tibial inserts.

DOI： 10.1016/B978-0-85709-128-4.50008-X

Language：English   Publishing type：Research paper (scientific journal)  

With various daily activities, the effectiveness of adsorbed film formed on a gel-like layer at the uppermost superficial articular cartilage in natural synovial joints becomes important to control the friction and wear of articular cartilage in mixed or boundary lubrication regime as an adaptive multimode lubrication mechanism. Furthermore, in the case where the adsorbed film has been removed, the proteoglycan gel layer is expected to preserve low friction and protect against the wear of bulk cartilage tissue with an effective hydration lubrication mechanism. Besides, it is indicated that the biphasic lubrication plays an important role in lowering of friction in articular cartilage containing a large amount of water. At the present stage, however, the detailed relationship between adsorbed films and hydrated gel layers has not yet been elucidated. In this article, the frictional behaviours of articular cartilage on a glass plate were observed in the reciprocating tests with the restarting process after interruption and unloading. The lubricating effectiveness of adsorbed films in hyaluronate (HA) solutions was examined using intact and partially damaged cartilage specimens. The role of albumin and g-globulin in relation to the surface conditions of gel layer is discussed. The restarting friction immediately after reloading became lower as a result of recovery of the effective interstitial fluid pressurization and hydration and adsorbed films have a significant effect on the frictional behaviour at local contacts. To clarify the molecular phenomena taking place under rubbing condition, in situ observations of the forming adsorbed film were conducted. The measurements were performed using the fluorescent staining method for protein and HA molecules at low contact pressures.

DOI： 10.1177/1350650111415756

Language：English   Publishing type：Research paper (other academic)  

This paper describes dry reciprocating sliding tests of polymers against some metallic materials in gaseous hydrogen. The polymers tested included PTFE, PTFE composites, PVDF and UHMWPE, while the metallic counterfaces included hardened bearing steel, austenitic stainless steel and cobalt-based alloy. The sliding tests revealed that friction and wear depended on the counterface materials, and that the initial running-in wear influenced the subsequent steady state friction and wear. XPS analysis showed that friction and wear of the four fluorine containing polymers depended on the formation of metal fluoride on the metallic counterface.

Language：Japanese   Publishing type：Research paper (scientific journal)  

Contact Analysis between Microscopic Surface Asperity of a Virgin Femoral Component and Ultra-High Molecular Weight Polyethylene

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)  

Publishing type：Research paper (international conference proceedings)  

Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Influence of Microscopic Surface Asperity of Metallic Femoral Component on the Wear of Ultra-high Molecular Weight Polyethylene Tibial Insert

Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Surface Analysis of the Tribological Pair Al2O3 Nanocomposites and Al2O3 in Different Media

Language：English   Publishing type：Research paper (international conference proceedings)  

The Development of Shoulder Motor Orthosis for Stroke Rehabilitation

Language：English   Publishing type：Research paper (international conference proceedings)  

Development of an Arm Model with a Bionic Elbow Joint

Language：English   Publishing type：Research paper (international conference proceedings)  

Finite Element Analysis of Cartilage Considering the Depth Dependence and Time Dependence of Young’s modulus under Constant Total Compressive Deformation

Language：English   Publishing type：Research paper (scientific journal)  

Effect of the conformational changes and differences of proteins on the frictional properties of Poly (vinyl alcohol) Hydrogel

Language：English   Publishing type：Research paper (international conference proceedings)  

In Situ Observation of Forming Boundary Film Composed of Synovia Constituents on Rubbing Surface of Artificial Cartilage Material

Language：English   Publishing type：Research paper (international conference proceedings)  

Mechanisms of Protein Boundary Film Formation for Poly (vinyl alcohol) Hydrogel as Artificial Cartilage Material

Language：English   Publishing type：Research paper (international conference proceedings)  

Transport phenomena in engineered cartilage with tissue development in agarose gel

Language：English   Publishing type：Research paper (scientific journal)  

Micro- and Nanoscopic Biotribological Behaviours in Natural Synovial Joints and Artificial Joints

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Tribological Analysis of Al2O3 Nanocomposites as an Alternative for Hip Joint Replacement Materials

Language：Japanese   Publishing type：Research paper (scientific journal)  

The Development of Elbow Orthosis with Motor Function

Language：Japanese   Publishing type：Research paper (scientific journal)  

An Experimental Study on the Delamination Mechanism of UHMWPE for Artificial Joints

Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1299/jsmec.48.555

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

An Experimental Study on the Cold Flow of UHMWPE Tibial Insert

Language：Japanese   Publishing type：Research paper (scientific journal)  

Mechanical Test of Temporary Cementation for Dental Implant Using a Mastication Simulator

Language：Japanese   Publishing type：Research paper (scientific journal)  

Noninvasive in vivo Human Capillary Vessel Blood Flow Analysis

Language：Japanese   Publishing type：Research paper (scientific journal)  

The Development of Micro Testing Machine Equipped with Microscope and Visualization Method for Investigation of Cartilaginous Tissue

Language：Japanese   Publishing type：Research paper (scientific journal)  

A Study on the Cold Flow of UHMWPE Tibial Insert in Knee Prostheses

Language：Japanese   Publishing type：Research paper (scientific journal)  

High Speed Observation of Human Capillary Vessel Loop and Blood Flow Analysis

Language：Japanese   Publishing type：Research paper (scientific journal)  

Effect of Gamma Irradiation on Wear Characteristics of UHMWPE for Joint Prostheses

Language：Japanese   Publishing type：Research paper (scientific journal)  

3-dimensional measurement of range of motion in the shoulder joint in consideration of successive motion

Language：Japanese   Publishing type：Research paper (scientific journal)  

Effect of protein boundary films on wear of artificial cartilage (2nd Report)

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1243/0954411041561018

Language：Japanese   Publishing type：Research paper (scientific journal)  

Evaluation of Wear Property of PVA Hydrogel as Artificial Cartilage and Effect of Protein Film on Wear-Resistant Property

Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1299/jsmec.46.594

Language：Japanese   Publishing type：Research paper (other academic)  

The Evaluation of Structual Role of Proteoglycan in Articular Cartilage under Constant Compression

Language：Japanese   Publishing type：Research paper (other academic)  

Effect of Protein Adsorbed Films on Wear of Artificial Cartilage

Language：Japanese   Publishing type：Research paper (other academic)  

Finite Element Analysis of Cold Flow in UHMWPE Tibial Component -Influence on Stress Distribution and Wear Behavior-

Language：Japanese   Publishing type：Research paper (other academic)  

Study on Surface Morphology of Human Osteoarthritic Cartilage with Atmic Force Microscopy

Language：Japanese   Publishing type：Research paper (scientific journal)  

Evaluation of Wear Characteristics of Artificial Joint Materials in the Multi-Directional Pin-on-Plate Tester

Language：Japanese   Publishing type：Research paper (scientific journal)  

Modelling of Articular Cartilage Containing Chondrocytes and Finite Element Analysis for Articular Cartilage and Chondrocytes Under Compression

Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (other academic)  

Examination of Chondrocytes within Articular Cartilage Using Confocal Laser Scanning Microscopy and Analysis of Stress-Strain Transmission

Language：Japanese   Publishing type：Research paper (other academic)  

Elasto-Plastic Contact Analysis on Fatigue Wear Behavior of UHMWPE Tibial Components

Language：Japanese   Publishing type：Research paper (other academic)  

Effect of Protein Ingredient on Friction and Wear of PVA Hydrogel as Artificial Cartilage

Language：Japanese   Publishing type：Research paper (scientific journal)  

Contact Analysis of UHMWPE Tibial Component Based on Geometrical Measurement for Retrieved Knee Prosthesis

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Plasma Carburized Titanium Alloy as Bearing Surface Material for Joint Prostheses

Language：Japanese   Publishing type：Research paper (other academic)  

Trajectory Analysis of Catching Motion in a Hand Using a Falling Weight and Three Dimensional Position Sensor

Language：Japanese   Publishing type：Research paper (other academic)  

Evaluation of Wear in Retrieved Knee Prostheses

Language：Japanese   Publishing type：Research paper (other academic)  

Strain Analysis of Articular Cartilage Using Finit Element Method

Language：Japanese   Publishing type：Research paper (other academic)  

Friction and Wear Properties of PVA Hydrogel

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (other academic)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Surface layer of articular cartilage observed by atomic force microscopy in liqid - Morphology and role in joint lubrication -

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (other academic)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：English   Publishing type：Research paper (international conference proceedings)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Study on Morphology and Lubrication of Articular Cartilage Surface with Atomic Force Microscopy

Language：Japanese   Publishing type：Research paper (scientific journal)  

Evaluation of in vivo Fixation and Stabilization of Polyvinyl Alcohol Hydrogel for Artificial Cartilage

Responsible for pages：pp.221-245   Language：English   Book type：Scholarly book

Responsible for pages：Chapter 6 in Polymer Tribology, pp195-226   Language：English   Book type：Scholarly book

Responsible for pages：pp.245-277   Language：English   Book type：Scholarly book

Responsible for pages：pp.36-46   Language：English   Book type：Scholarly book

Responsible for pages：pp.37-47   Language：English   Book type：Scholarly book

Responsible for pages：pp.42-52   Language：English   Book type：Scholarly book

Event date： 2023.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyoto   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Bari   Country：Italy  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川越市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川越市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川越市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川越市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2023.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2023.2

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.2

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2023.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2022.12

Language：English   Presentation type：Oral presentation (general)  

Venue：New Delhi   Country：India  

Event date： 2022.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Stockholm   Country：Sweden  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福井   Country：Japan  

Event date： 2022.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Taiwan, Province of China  

Event date： 2022.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Taiwan, Province of China  

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon   Country：France  

In order to understand the mechanism of the extremely low friction between articular cartilages, the synovial
joint lubrication was experimentally reproduced by using pseudo synovial fluid (PSF) and cartilage tissue model
in which living chondrocytes were seeded in agarose gels and cultured to elaborate extracellular matrix (ECM).
Friction tests were conducted using rheometer to evaluate the effect of synthesized ECMs and synovial fluid
(SF) components on friction property. From results of the friction test, we concluded that the former reduced
the shear resistance of the model surface, while the latter prevented the adsorption of hydrogel surface.

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon   Country：France  

The aim of this study is to investigate the effects of surface gel layer on friction properties of articular cartilage
in the mixed lubrication regime. In this work, the frictional characteristics of articular cartilage with different
treatments have been studied over a range of sliding speed and normal loads by Nano Tribometer. The results
show that the preprocessing with the ultrasonication removed a part of surface gal layer and produced a
significant increase in COF compared with the control cartilage; the effect of preprocessing with the tube mixer
was limited. Synovial fluid has an effective lubrication effect on both the intact and the damaged cartilages.

Event date： 2022.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Lyon   Country：France  

In this study, tribological characterization of UHMWPE-based nanocomposites was carried out to understand
the wear mechanism and behavior of them. Multiwall carbon-nanotube (MWCNT), nanodiamonds (ND) and
graphen oxide (GO) were selected as carbon-based nanomaterial reinforcement. Multi-directional pin-on-disk
wear test was conducted for tribological characterization for orthopaedic applications. From the wear test, all
samples showed relatively low wear, especially UHMWPE-MWCNT. Surface images of metal disk showed
less wear scars, mainly adsorption of lubricant constituents. In polymeric pin surface images, UHMWPE-GO
had severe worn surface comparing to the others. It can be concluded that addition of carbon-based
nanocomposites contributes to the improvement of wear resistance significantly.

Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.5

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：English   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2022.1

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.8

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：オンライン   Country：Japan  

Event date： 2021.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Malaysia  

Event date： 2021.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.4

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.1

Language：English   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2021.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Event date： 2020.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Online   Country：Japan  

Many previous studies have been conducted to clarify the detailed lubrication mechanism of our synovial joints and to unravel the mystery of extremely smooth joint movements. Sliding surfaces in natural synovial joints are covered with soft and highly hydrated articular cartilage and lubricated with synovial fluid. Despite several different lubrication mechanisms have been proposed, some latest studies are emphasizing the importance of the boundary lubrication at the cartilage surface. However, there are still very active discussions about the lubrication effect of biological molecules contained in the synovial fluid and the cartilage surface, and also the contribution of porous, permeable and hydrated nature of cartilage tissue. In this study, the joint articulation was modeled with glass-on-natural articular cartilage and glass-on-hydrogel cartilage models. Their frictional characteristics was evaluated in the model synovial fluid to explore the boundary lubrication mechanism of the synovial joint.
Square shaped articular cartilage samples (8 mm x 8 mm) were harvested from the proximal end of the bovine middle phalanx within 24h of sacrifice. The frictional characteristics of the cartilage surface was explored by using a smooth glass probe (2 mm diameter) and Nano Tribometer (Anton Paar NTR3) under 5 to 100 mN loads. The cartilage surface was modified by certain treatments and their influence on the frictional behavior was examined.
A synthetic polymer hydrogel, polyvinylalcohol (PVA) hydrogel with 79 wt% water content, was chosen as a simple analogue of articular cartilage to include soft, porous and hydrated nature of the cartilage tissue in the friction test. The frictional behavior between a glass roller and the hydrogel cartilage model was evaluated in reciprocating sliding tests. Representative synovial fluid constituents, such as serum proteins, phospholipids and hyaluronic acid was added to the model synovial fluid and their lubrication effect was examined.
In addition, hydrogel-chondrocytes constructs were prepared as quasi-cartilage models containing living cells. This model was cultured for a few weeks and the evolution of lubrication ability in the cartilage model was monitored through a friction test to examine the contribution of extra cellular matrixes (ECMs) to the boundary lubrication. The characteristic velocity-depended frictional behavior of the hydrogel cartilage model was examined by the rotational rheometer (Anton Paar MCR301).

Event date： 2020.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2020.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2020.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2020.1

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Fukuoka   Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Kagoshima   Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Kagoshima   Country：Japan  

Event date： 2019.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Bangalore   Country：India  

Event date： 2019.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Singapore   Country：Singapore  

Event date： 2019.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Hnanice   Country：Czech Republic  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Sendai   Country：Japan  

Event date： 2019.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Singapore   Country：Singapore  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Chengdu   Country：China  

Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Tokyo   Country：Japan  

Event date： 2019.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：Tokyo   Country：Japan  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Nashville   Country：United States  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Nashville   Country：United States  

Event date： 2019.5

Language：English   Presentation type：Oral presentation (general)  

Venue：Nashville   Country：United States  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川崎市   Country：Japan  

Event date： 2019.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：川崎市   Country：Japan  

Event date： 2019.1

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2018.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Taipei   Country：Taiwan, Province of China  

Event date： 2018.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Taipei   Country：Taiwan, Province of China  

Event date： 2018.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Taipei   Country：Taiwan, Province of China  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：伊勢   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：伊勢   Country：Japan  

Event date： 2018.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：伊勢   Country：Japan  

Event date： 2018.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Chicago   Country：United States  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Montreal   Country：Canada  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Montreal   Country：Canada  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Montreal   Country：Canada  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Portoroz   Country：Slovenia  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kuching   Country：Malaysia  

Event date： 2018.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kuching   Country：Malaysia  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Event date： 2018.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：大阪   Country：Japan  

Event date： 2018.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：裾野市   Country：Japan  

Event date： 2018.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：裾野市   Country：Japan  

Event date： 2018.7

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：裾野市   Country：Japan  

Event date： 2018.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Uppsala   Country：Sweden  

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2018.5

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Carbon film formation on the surface of carbon fiber filled PTFE during sliding in High-purity　Hydrogen (Second report)

Event date： 2018.3

Language：English   Presentation type：Oral presentation (general)  

Venue：Kumamoto University (Kumamoto)   Country：Japan  

Event date： 2018.3

Language：English   Presentation type：Oral presentation (general)  

Venue：Kumamoto University (Kumamoto)   Country：Japan  

Event date： 2018.3

Language：English   Presentation type：Oral presentation (general)  

Venue：Kumamoto University (Kumamoto)   Country：Japan  

Event date： 2018.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学（福岡市）   Country：Japan  

Event date： 2018.2

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu University (Fukuoka)   Country：Japan  

Event date： 2018.2

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu University (Fukuoka)   Country：Japan  

Event date： 2018.2

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu University (Fukuoka)   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都大学（京都市）   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都大学（京都市）   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学（福岡市）   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学（福岡市）   Country：Japan  

Event date： 2017.12

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：九州大学（福岡市）   Country：Japan  

Event date： 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：サンポートホール高松（高松市）   Country：Japan  

Event date： 2017.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：サンポートホール高松（高松市）   Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Venue：サンポートホール高松（高松市）   Country：Japan  

Event date： 2017.11

Language：English   Presentation type：Oral presentation (general)  

Venue：サンポートホール高松（高松市）   Country：Japan  

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：久留米工業高等専門学校（福岡）   Country：Japan  

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：久留米工業高等専門学校（福岡）   Country：Japan  

Event date： 2017.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：久留米工業高等専門学校（福岡）   Country：Japan  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Southwest Jiaotong University (Chengdu)   Country：China  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (invited, special)  

Venue：Southwest Jiaotong University (Chengdu)   Country：China  

Event date： 2017.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Beijing International Convention Center (Beijing)   Country：China  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Universiti Teknologi Malaysia (Kuala Lumpur)   Country：Malaysia  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Universiti Teknologi Malaysia (Kuala Lumpur)   Country：Malaysia  

Event date： 2017.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Universiti Teknologi Malaysia (Kuala Lumpur)   Country：Malaysia  

Event date： 2017.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Sapporo   Country：Japan  

The word “Biotribology” was defined in 1971 to embrace “all aspects of tribology (friction, wear
and lubrication) concerned with biological systems”. It covers many events encountered during our
daily life as research interests, for example, friction between a glass and fingers for gripping, wear of
teeth during brushing and so on. Among them, the lubrication mechanism of natural synovial joint is a
popular research topic in biotribology. The smooth movement of human diarthrodial joints has
attracted huge interests of researchers not only in biomedical filed but also in engineering field, since
the typical friction coefficient of synovial joints is extremely lower, around 0.001, compared with that
of man-made bearing systems, those friction coefficient is usually 0.1 to 0.01. The wear of prosthetic
joint materials is another important issue for biotribology. Metal ions and polymer wear particles
released from sliding surfaces of joint prosthesis implanted in human body are usually very toxic and
exert adverse reactions in the surrounding living tissue Therefore, it is recognized as a main factor
restricting the lifetime of current artificial joints. This presentation attempts to present recent progress
of biotribology research on the natural synovial joint and joint replacements.

Event date： 2017.6

Language：English   Presentation type：Oral presentation (general)  

Venue：Ljubljana   Country：Slovenia  

Event date： 2017.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2017.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2017.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2016.3

Presentation type：Oral presentation (general)  

Venue：熊本市   Country：Japan  

Event date： 2016.2

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2016.2

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2016.1

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2016.1

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2015.12

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2015.12

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2015.11

Presentation type：Oral presentation (general)  

Venue：Penang   Country：Malaysia  

Event date： 2015.11

Presentation type：Oral presentation (general)  

Venue：Penang   Country：Malaysia  

Event date： 2015.11

Presentation type：Oral presentation (general)  

Venue：Penang   Country：Malaysia  

Event date： 2015.10

Presentation type：Oral presentation (general)  

Venue：Denver   Country：United States  

Event date： 2015.10

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2015.10

Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：東京都   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：東京都   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：東京都   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：札幌市   Country：Japan  

Event date： 2015.9

Presentation type：Oral presentation (general)  

Venue：札幌市   Country：Japan  

Event date： 2015.5 - 2015.6

Presentation type：Oral presentation (general)  

Venue：Toronto   Country：Canada  

Event date： 2015.5

Presentation type：Oral presentation (general)  

Venue：姫路市   Country：Japan  

Event date： 2015.5

Presentation type：Oral presentation (general)  

Venue：姫路市   Country：Japan  

Event date： 2014.3

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：京都市   Country：Japan  

Event date： 2014.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.2

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.1

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.1

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2014.1

Language：English   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.12

Language：English   Presentation type：Oral presentation (general)  

Venue：Singapore   Country：Singapore  

Event date： 2013.11

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.10

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡市   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2013.9

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：鹿児島市   Country：Japan  

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Torino   Country：Italy  

In this study, the gas sealing ability and wear behavior of polymer composites in gaseous hydrogen were evaluated as the index of sealing parts performance. The experimental results show that differences in the filler materials of PTFE composites and the metal surface roughness affect both hydrogen sealing ability and volumetric wear rate.

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Torino   Country：Italy  

In this study, effects of phospholipids contained in synovial fluid on the volumetric wear rate and friction coefficient of UHMWPE/Co-Cr-Mo sliding pair were evaluated. In addition, influences on morphological characteristics of polyethylene wear particles were examined too. The multidirectional sliding pin-on-plate wear tester was employed to reproduce the in vivo wear behavior of artificial hip. The reciprocating friction tester was also employed to explore the frictional behavior in detail.

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Torino   Country：Italy  

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Torino   Country：Italy  

In this study, a traction loading was applied to the surface of chondrocyte-agarose construct, a model of regenerative cartilage tissue, and effects on the metabolism of chondrocytes cultured in the agarose construct and subsequent development of cartilage tissue were examined.

Event date： 2013.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

Event date： 2013.6

Language：Japanese   Presentation type：Oral presentation (general)  

Venue：福岡   Country：Japan  

Event date： 2013.5

Language：English   Presentation type：Oral presentation (general)  

Venue：東京   Country：Japan  

The Oxidation Behavior and Wear Properties of Shelf-aged Gamma- irradiated UHMWPE

Event date： 2013.3

Language：Japanese  

Venue：東京   Country：Japan