Abstract: The research of the stress distributions and the structural deformation at the sliding core
in artificial intervertebral disc under the dorsiflexion is becoming more significant. This research
analyzes the finite element model of sliding core and evaluates the effect of radius of curvature and
the friction coefficient at the sliding core on von-Mises stress and the contact pressure. New Models
of the artificial intervertebral disc are suggested by the results of the sliding core is evaluated by the
comparison of that of SB Charité III. Based on the above facts, the optimized radius of curvature of
the sliding core is also suggested.
Abstract: Poly-N-isopropylacrylamide (PNIPA) gel is a typical thermo responsive gel which
undergoes a large volume change from the low-temperature swollen phase to the high-temperature
shrunken phase. In this study, the mechanical behavior of PNIPA gels was investigated by the
experiment and simulation. The cylindrical shaped specimens of PNIPA gel were prepared and
tensioned at various temperature. Swelling ratio at equilibrium state was calculated by diameter of
swelling gels. Young modulus was obtained from stress-strain curve plotted using tensile load
measured by semiconductor gauge. Also swelling and deswelling behavior of thermo sensitive gel
were simulated by using finite element method. Polymer-solvent interaction parameter, χ was used as
a function of temperature. Calculated swelling ratio at equilibrium was compared with experimental
result and theoretical swelling curve. Furthermore, change of volume fraction and stress distribution
in swelling process were evaluated.
Abstract: Many kinds of materials are currently used as artificial bone substitutes. Hydroxyapatite
(HA), the same as the main inorganic component of bone, is one of commonly used bio-ceramics
and has excellent bioactivity and biocompatibility with hard tissues. However, it has problems as
the bone filler or bone tissue-engineering scaffold due to low fracture toughness and low
degradation rate. Recently, biodegradable materials for bone tissue have been developed to respond
the requirement. Collagen, the same as the main organic component of bone, is biocompatible,
biodegradable and promotes cell adhesion. A composites associated with HA is expected to have
early osteoconduction and bone replacement ability. The present study was to fabricate bone-like
composites consist of HA and collagen. Besides the ossiferous ability of the material in vivo is
evaluated by using rabbits. Bone-like composites were successfully fabricated in this study,
associating the collagen with HA. And the composites presented good osteoconductive and bone
Abstract: Evaluations of elasto-plastic properties and fracture strength were studied utilizing
indentation technique. The elasto-plastic properties of nine monolithic metals were estimated using
dual indentation method and compared to the properties under tensile loading test. This method could
predict stress - strain curve and was found to determine ultimate tensile strength. For brittle coating,
fracture strength of diamond -like carbon (DLC) film was estimated by hybrid indentation with
acoustic emission (AE), corrosion potential fluctuation (CPF) and finite element method (FEM). AE
and CPF data provided information on the timing of film cracking and its mechanism. Fracture
strength of the films could be evaluated using Vickers and Rockwell indentation.
Abstract: To analyze the effect of the crystal orientations and the grain size on the Young's modulus
of thin polysilicon microelements, two-dimensional finite element models in plain strain condition
were developed using a Voronoi structure. The number of grains in a model of a 10 μm square area
was changed from 23 to 1200. The grain size and the crystal orientation of the film were analyzed by
means of an electron back-scattering diffraction pattern (EBSP) method. The average grain size of the
front surface of the thin film was about 0.69 μm, which is almost equal to the grain size of the Voronoi
model having 300 grains. From the results of EBSP analysis, the specimen had no oriented structure.
Therefore, random crystal orientation was given to each grain of the FEM models. When the number
of grains increased, the Young's modulus converged on about 171 GPa and its scatter caused by the
different sets of the random orientation was reduced. The Young's modulus obtained by the FEM
analysis was larger than the value obtained by the tensile tests.
Abstract: In this study we presented kinematic and kinetic data of foot joints by using passive
elastic characteristics of joints during gait. During the calculation process we used approximate
equations and partial plantar pressures. The maximum angular displacements of each
tarsometatarsal joint ranged from 4o to 7o and the maximum moments were from 200N⋅cm to
1500N⋅cm. It was relatively wide distribution. Foot kinematic data calculated from the
approximated equations, which were represented by the correlation between moment and angular
displacement, and the data from motion analysis were very similar. We found that the movements
of foot joints were mainly decided by the passive characteristics of the joints when ground reaction
force acts. The kinematic and kinetic analysis using approximated equations which is presented in
this study can be usefully applied to describing the movements of foot joints during gait.
Abstract: Self-oscillating gel is designed by copolymerizing the catalyst for the
Belousov-Zhabotinsky (BZ) reaction with thermosensitive polymer. The cylindrical-shaped
specimens of NIPAAm-co-(Ru(bpy)3 gel were prepared by copolymerizing (Ru(bpy)3) monomer as
catalyst with NIPAAm as thermosensitive polymer. Swelling behavior during self-oscillating of gel
by BZ reaction was observed using CCD camera and the force due to this reaction was evaluated
using semiconductor gauge. Self-oscillating swelling-deswelling behavior in samples with different
swelling ratio was evaluated by this apparatus, and mechanical parameters such as Young’s modulus,
stress amplitude and oscillating period were quantitatively estimated.
Abstract: Natural clay minerals are ideal nanofillers for polymer materials and have been attracted
tremendous research and development interests in the past decade. The manufacture of clay
nanofillers relies largely on the exfoliation of clay particle into individual clay platelets. Thus,
understanding the interlayer swelling of clay minerals upon the adsorption of surfactants is important
to the fabrication and design of polymer nanocomposites. This paper reports our recent experimental
and theoretical studies on a variety of organoclays that show a linear relationship between the increase
of d-spacing and the mass ratio between organic and clay.
Abstract: Four kinds of dimers from cyclic peptide [-(1R, 3S)-γ-Acc-D-Phe]3 were investigated
using molecular modeling based on the density functional theory (DFT), molecular mechanics (MM)
and molecular dynamics (MD). The equilibrium dimer structures reveal that these dimers can be
divided into two different types according to stacking formation, in which one type dimer is more
stable due to the effect of side chain groups. In each type of dimers, only one can transport CHCl3.
When the terminal N-substituent methyl is introduced, the transport character is reversed. Analysis
of 500 ps MD trajectory suggests that the inner and terminal sizes of the dimers are the main factor
that affects the transport of CHCl3. The modeling results can provide a new way for designing and
synthesizing cyclic peptide transport channels.
Abstract: The mechanical properties of bone have been found varying at different structural levels.
The different mechanical properties might indicate some important information, such as the
ultrastructure of various bone tissue. Descriptions of the structural features of bone are intensive in
current studies. However, the mechanical properties of bone, in particular those at the micro-and
nanostructural level (material level) remain poorly understood. To probe the mechanical properties
at the microstuctural level, the nanoindentation technique is applied. Nanoindentation as a
promising technique is widely used in the materials science community for probing the mechanical
properties of thin films, small volumes, and small microstructural features. Nanoindentation has
been shown to be an effective method to probe the mechanical properties of microstructures at the