bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatigue Damage Mechanism of Nanocrystals in ECAP-Processed Copper Investigated by EBSD and AFM Hybrid Methods
Authors: Kimura Hidehiko , Kojima Yuka , Akiniwa Yoshiaki , Tanaka Keisuke , Ishida Takaaki
Published: March 2009

Electron backscattering diffraction, EBSD, technique as well as atomic force microscopy,
AFM, was employed to investigate fatigue damage mechanism in ultrafine-grained copper
processed by equal channel angular pressing, ECAP. The fatigue damage evolution under axial
tension compression was investigated. The results show that linearly shaped fatigue damage was
introduced in the scale of micrometers in spite of the average grain size of 300 nm. The linear
damage was randomly oriented when the shear direction of the last ECAP-pressing in perpendicular
to the loading axis. The orientation analysis by EBSD revealed that the linear damage is introduced
in the area with the same crystallographic orientation in the direction of the maximum Schmid
factor as in the slip deformation in coarse-grained materials. The comparison before and after
fatigue tests shows the grain coarsening in the area where large linear fatigue damage was formed.
It is considered that strain concentration at the edge of the slips introduced in a relatively coarse
ultrafine grain causes the grain rotation and deformation in the adjacent nano-sized grains, resulting
in the grain coarsening and subsequent propagation of the slips in the order of micrometers.
Molecular Dynamics Analysis on Initial Texture and Processing Route Influences on Grain Refinement Behavior of α-Fe by Equal Channel Angular Pressing
Authors: Matsumoto Ryosuke , Hayashida Toshio , Nakagaki Michihiko
Published: March 2009

Fine-grained polycrystalline metals have a very high yield stress and excellent workability.
Hence, numerous researchers are trying to develop an efficient process to obtain such materials. Our
goal is to develop an efficient severe plastic deformation (SPD) process through investigating
grain-refinement mechanisms in Equal Channel Angular Pressing (ECAP). In this paper, a series of
molecular dynamics (MD) simulations of severe simple-shear deformations, which are ideally
equivalent to SPD applied by typical ECAP processing routes, is performed using three-dimensional
models that are thin and have a square shape with a periodic-boundary condition. We analyze the
influences of the processing route and initial texture on the microstructural evolution. It is shown that
twinning deformations are dominant under the calculated conditions, and that the structural evolution
is notably affected by the relationship between the applied simple-shear direction and the
characteristic crystal orientation, which can easily cause a twinning deformation. We conclude that
Route A, without a rotation of the billet between processes, is the most efficient route. This is because
twinning deformations along the simple-shear direction interact with the twin boundaries developed
by the stress-component conjugate to the simple-shear. Furthermore, we demonstrate that the
influence of the initial texture difference remains in force during multiple processes that have the
same sliding plane.
Ectopic Osteoinduction by Variously Demineralized Allogenic Cortical Bone Matrix
Authors: Kim J.T. , Kang H.J. , Kim H.N. , Choi J.Y. , Lee J.M. , Park Eui Kyun , Shin Hong In
Published: March 2009

To improve ostegenic healing efficiency by demineralized bone matrix, we evaluated
the ectopic bone formation induced by variously demineralized allogenic cortical bone matrices
at subcutaneous and muscular sites in rats. The rat tubular cortical bone matrices were
demineralized in heated 0.6N HCl at 60 °C for 5 and 20 mins, respectively, using a controlledheat
ultrasonic cleaner and implanted in rat dorsal subcutaneous pouches and thigh muscles for
1-3 weeks. The influence of the demineralized condition of bone matrix on cellular proliferation
and osteogenic differentiation was also evaluated in vitro by MTT assay and ALP staining. The
cortical matrices were completely demineralized within 20 mins by sonication and heating of
diluted 0.6 N HCl. The sonicated bone matrices in heated acidic solution at 60 °C revealed no
adverse immunogenic and inflammatory response in vivo regardless of demineralized condition.
Cellular proliferation and osteoblastic differentiation was facilitated by more fully
demineralized. Ectopic bone formation was induced only by demineralized bone matrices and
were more favorable in fully demineralized matrices. The ectopic bone induction was more
favorably in subcutaneous pouches than in muscular tissue. These findings suggest that a fully
demineralized cortical bone matrix maximizes osteogenic repair by exposing more bioactive
molecules which in turn induce chondro- and osteognic differentiation of mesenchymal cells
around the implanted matrices, and that the sonication of diluted 0.6 N HCl heated at 60 ° C is a
rapid and effective method for sterile demineralized graft preparation.
Microscopic Multi-Directional Mechanical Properties of Human Femoral Cancellous Bone Tissue
Authors: Park Young Hwan , Cha Hee Sung , Hong Jung Hwa
Published: March 2009

Multi-directional mechanical properties of human cancellous bone tissue were never
measured using a compressive test with microscopic cubic specimens. In this study, a small scale
compressive testing machine with nano meter resolution and a measurement system for Poisson’s
ratio with sub-nano meter resolution were developed to measure accurate microscopic mechanical
properties of human CBT. The measured mean longitudinal (E1), postero-anterior (E2), and lateromedial
(E3) elastic moduli were 3.47 GPa (S.D. ±0.41), 2.57 GPa (S.D. ±0.28), and 2.54 GPa (S.D.
±0.22), respectively. ANOVA showed that the longitudinal elastic modulus (E1) was significantly
(p < 0.01) greater than the postero-anterior (E2) and latero-medial (E3) elastic moduli. For Poisson’s
ratios, ν12 was significantly (p <0.01) higher than ν23 and ν31.
Regeneration of Bone Defect Using Micro-Bioceramic PLLA Polymer Scaffolds Synthesized by Nonsolvent and Solvent Method
Authors: Park Min Sung , Jung Young Mee , Kim Soo Hyun , Kim Sang Heon , Kim Young Ha , Min Byoung Goo , Lee Jin Woo
Published: March 2009

Poly-L-lactic acid (PLLA) is a desirable and very attractive polymer for fabricating
porous scaffolds. As of now, a solvent casting method with organic solvents has been used in
scaffold fabrication process. However, residual organic solvents in the scaffolds have the problems
of decreasing the effect of osteogenic induction due to the hindrance of bioceramic by polymer
solution and it’s harmfulness in vivo. To avoid these disadvantages of scaffolds by organic solvent
casting method, we developed a new method fabricating polymer (PLLA)/ceramic (β -TCP)
composite scaffolds by baking method without using solvent, and then we tested properties of
scaffolds on animals. As the result, non-toxicity has been proved through animal experiment and
newly fabricated polymer/ceramic composites by a novel sintering method were induced rapid bone
regeneration through enhancing the interaction of cells and a bone induction factor without any host
immune response.
Reinforcement Fibrin-Hyaluronic Acid Composite Gel for Tissue Engineering Cartilage Genesis
Authors: Park Sang Hyug , Park So Ra , Min Byoung Hyun
Published: March 2009

The reimplantation method of cultured chondrocytes broadly has been offered as an
alternative for articular cartilage repair. A variety of biologically derived and synthetic polymeric
and hydrogel materials also have been investigated for good cell delivery efficiency. Preciously, we
examined the feasibility of fibrin gel, mixed with hyaluronic acid(HA) as a cell delivery carrier. In
order to reinforce the material, hybrid biomaterials of fibrin/HA composite gels with fibrinolysis
inhibition factors(FIFs: aprotinin, DI101, EACA) have been investigated in the present work
because we did not satisfy a little progress. These fibrin/HA composite gels added FIFs maintained
their structural integrity in long-term culture over 4th weeks. Contrary to our expectation the mass of
the fibrin/HA composite with DI 101 was significantly superior to the ones of other combinations.
In histological evidence, all of them are showed good positive result of stain of Safranin-O and
alcian blue during the culture period. In gross examination, samples of all groups grossly resembled
cartilage in color and were resistant to external compression. Our study demonstrates that most
favorable polymer can be used good quality tissue engineered cartilage and in this culture systems
have been useful for studying the basic biology of chondrocyte biosynthesis of ECM and new
cartilage matrix formation without a loss of volume. After all, we proved the safety of inhibitors of
the fibrinolytic system without hazardous effect on cell behavior and found out that DI 101 would
be the most effective agent.
In Vitro Proliferation of Various Human Dental Stem Cells
Authors: Kook Sun Young , Jo You Young , Lee Hee Jung , Seo Byoung Moo , Choung Pill Hoon
Published: March 2009

To ascertain the properties of human dental stem cells, various postnatal human stem
cells were isolated from extracted human teeth and jawbones. Isolated dental stem cells were plated
until losing their ‘stemness’ and were evaluated for their proliferation rate, colony forming
efficiency, and expression of a specific stem cell marker. These dental stem cells have the potential
to proliferate for more than 10 passages, except for the maxillary bone marrow stem cells
(MXBMSCs). In particular, stem cells obtained from the periapical follicle (PAFSCs) were
definitely superior to the other dental stem cells in proliferation, colony forming efficiency and
expression of specific stem cells marker.
Vascular Smooth Muscle Cell Behaviors onto Epigallocatechin- 3-O-Gallate-Blended L-Lactide/ε-Caprolactone Copolymers
Authors: Han Dong Wook , Cho Han Hee , Jung Duk Young , Lee J.J. , Matsumura Kazuaki , Park Jong Chul , Hyon Suong Hyu
Published: March 2009

In this study, such behaviors of vascular smooth muscle cells (VSMCs), as proliferation
and migration, with serum stimulation were investigated onto (−)-epigallocatechin-3-O-gallate
(EGCG)-blended poly(L-lactide-co-ε-caprolactone, PLCL) copolymers (EGCG-b PLCL). VSMCs
were primarily cultured from rat aorta, and EGCG-b PLCL films were fabricated by mixing PLCL
with EGCG. The proliferation of VSMCs cultured onto EGCG-b PLCL film was significantly
suppressed in spite of serum induction. Moreover, recovery of denuded area by VSMCs receiving
conditioned media obtained from EGCG-b films was completely inhibited, whereas VSMCs onto
intact films migrated into denuded area in response to serum showing essentially complete recovery.
These results suggest that inhibition in the behaviors of serum-stimulated VSMCs may be mediated
through the anti-proliferative effects of EGCG released from polymer films, and EGCG-b polymers
can be applied for fabricating an EGCG-eluting vascular stent.
Preparation and Characterization of Natural Hydroxyapatite from Animal Hard Tissues
Authors: Lü Xiao Ying , Fan Yong Bin , Gu Dachun , Cui Wei
Published: March 2009

The purpose of this study is to find out an effective method to prepare natural
hydroxyapatite (HA) from biological source, i.e., pig bones, pig teeth, and extracted human teeth.
For the preparation of natural HA a calcining method with different temperatures was used, in
combination with the thermal gravimetric analysis (TGA). Three analysis methods, i.e., Fourier
transform infrared spectroscope (FTIR), X-ray diffraction (XRD), and inductively coupled plasma
(ICP) have been used to investigate the characteristics of the prepared materials. The spectrum of
the prepared material, obtained by means of FTIR and XRD, are consistent with the standard FTIR
spectrum and JCPDS index of XRD of hydroxyapitite. It confirms that the material prepared is
hydroxyapitite indeed. The natural HA obtained by calcining at 850°C shows a desired quality.
Preparation of Macroporous Hydroxyapatite/Chitosan-Alginate Composite Scaffolds for Bone Implants
Authors: Jin Hyeong Ho , Lee Hyang Mi , Park Ik Min , Park Hong Chae , Yoon Seog Young
Published: March 2009

Porous HAp/chitosan-alginate composite scaffolds were successfully synthesized by insitu
co-precipitation method. During the preparation of HAp/chitosan-alginate composite scaffolds,
the interaction between chitosan-alginate molecules would be reduced with increasing HAp content,
with the resulting that the chitosan-alginate molecules were homogeneously dispersed in the
composite scaffolds. The chitosan-alginate content was found to be almost consistent as initially
added during the preparation. These results imply that chitosan-alginate was almost perfectly
incorporated into the composites. It was found that the pore structure of the composite scaffolds
with low HAp content was similar to chitosan-alginate scaffolds, and the morphology of uniform
microstructure was unaffected by the presence of HAp. However, the pore diameter decreased with
increasing the HAp content up to HAp content of 30 wt%, eventually the pore structure was
collapsed and the composites scaffolds appeared to be agglomerated at higher HAp content.
Rapid Cell Sheet Recovery by Successive Grafting of PHEMA and PIPAAm onto TCPS Dish Surfaces
Authors: Ko Young Gwang , Yoon Kwan Han , Jang Jin Ho , Yamato Masayuki , Kikuchi Akihiko , Okano Teruo , Kang Inn Kyu , Kwon Oh Hyeong
Published: March 2009

Rapid recovery of cell sheets is considered important to maintain the biological function
and viability of recovered cell sheets. To accelerate required culture substrate hydrophilic/
hydrophobic structural changes in response to culture temperature alteration, poly(2-hydroxyethyl
methacrylate) (PHEMA) and poly(N-isopropylacrylamide) (PIPAAm) were grafted successively
onto tissue culture polystyrene (TCPS) dishes by electron beam irradiation. Analysis by attenuated
total reflection-Fourier transform infrared revealed that PHEMA and PIPAAm were successfully
grafted to surfaces of TCPS dish. PIPAAm-PHEMA-grafted TCPS (PIPAAm-PHEMA-TCPS)
dishes were compared with PIPAAm-grafted TCPS dishes for cell sheet detachment experiments.
Approximately 75 min was required to completely detach cell sheets from PIPAAm-TCPS dish,
compared to only 13 min to detach cell sheets from PIPAAm-PHEMA-TCPS dish, which is
successively grafted with PHEMA and PIPAAm. PHEMA is a well-known as a high hygroscopic
polymer. In the case of PIPAAm-PHEMA-TCPS dish, PHEMA layer acted as a water pool to
accelerate the hydration of PIPAAm layer due to the effective and simultaneous water supply to
PIPAAm layer, resulting in rapid hydration of grafted PIPAAm molecules and detachment of cell
sheet compare to PIPAAm-TCPS dish without PHEMA layer.
Evaluation of Semi-Interpenetrating Polymer Networks Composed of Chitosan and Poloxamer for Artificial Skin
Authors: Kim In Yong , Seo Seog Jin , Yoo Mi Kyong , Kim Bom Chol , Kim Se Kwon , Lee Hyun Chul , Cho Chong Su
Published: March 2009

The ideal dermal matrix should be able to provide the right physical and biological
environment to ensure homogenous cell and extracellular matrix (ECM) distribution, as well as the
biocompatible interactions with tissue. Chitosan (CS)/poloxamer semi-interpenetrating polymer
networks (SIPNs) was prepared by crosslinking of poloxamer macromer in the presence of CS in
order to improve its mechanical property required in skin tissue engineering application.
Furthermore, we also prepared CS/poloxamer SIPNs with ShebaTM, human acellular dermis, to
overcome a low biocompatibility of the CS/poloxamer SIPNs. The CS/poloxamer SIPNs/ShebaTM
showed remarkably highly cell attachment and viability in the two-dimensional (2D) culture and
similar cell morphology on the CS/poloxamer SIPNs/ShebaTM compared with on tissue culturing
polystylene (TCPS) as a positive control. These results suggest that CS/poloxamer SIPNs
containing ShebaTM have good possibility for artificial skin system application.
Characterization of Hydrophilized PCL Electrospun Sheet as an Efective Guided Bone Regeneration Membrane
Authors: Cho Wan Jin , Kim Jun Ho , Oh Se Heang , Lee Jin Ho
Published: March 2009

Electrospinning is a fabrication process that can produce highly porous nano-scale fiber-based
matrices using an electrostatically driven jet of polymer solution. This method represents an attractive
approach for polymeric biomaterial processing which provides the membrane structure that may retain
mechanical strengths, flexibility, and high surface area. In this study, we prepared a guided bone
regeneration (GBR) membrane with selective permeability, hydrophilicity, good mechanical strength and
adhesiveness with bone using polycaprolactone (PCL) and Tween 80 by the electrospinning method. The
prepared PCL and PCL/Tween 80 electrospun sheets were characterized via morphology observation,
mechanical property, water absorbability, and model nutrient permeability. It was observed that the
PCL/Tween 80 (3 wt%) electrospun sheet have an effective permeation of nutrients as well as the good
mechanical strength to maintain a secluded space for the bone regeneration. From the results, the
hydrophilized PCL/Tween 80 (3 wt%) electrospun sheet seem to be a good candidate as a GBR
membrane.
Characterization of the Gel-Spun Tubular Scaffold for Cardiovascular Tissue Engineering
Authors: Chung Eun Na , Kim Sang Heon , Ko Young Gun , Kwon Jae Hyun , Han Jeong Woo , Park In Su , Han Sung Sik , Kim Soo Hyun
Published: March 2009

A tubular and fibrous scaffold was fabricated from an elastic polymer, poly (L-lactideco-
ε-caprolactone) (PLCL; Mn 193,813, Mw 538,623) 50:50 by using a novel gel spinning
apparatus. To characterize the gel-spun scaffold, we investigated morphology, tensile property,
tissue in-growth rate and degradation rate. From SEM images, fibrous structure in the scaffold
wasn’t fabricated well in the condition of 4% gel concentration. In general, the thickness level of
microfibers increased as the gel concentration increased. In addition, the gel-spun scaffolds showed
stronger tensile properties in the circumferential direction than the longitudinal direction. 5%, 7.5%,
10% and 12.5% scaffolds were analyzed in both directions: circumferential direction and
longitudinal direction. On the other hand, the gel-spun scaffolds have been implanted in mouse to
examine the degradation rate in vivo and tissue in-growth aspects, compared to extruded scaffolds.
Both shows very similar degradation rates, but the aspect in tissue in-growth was different. In
conclusion, gel-spun PLCL scaffolds have good characteristics as a plausible scaffold for
cardiovascular tissue engineering.
Optimization of Scaffold for a Successful Hydrogel-Seeding Method for Vascular Tissue Engineering
Authors: Park In Su , Kim Sang Heon , Han Jeong Woo , Ko Young Gun , Chung Eun Na , Kim Soo Hyun
Published: March 2009

Porosity and pore size are needed for successful cell seeding and proliferation into porous
scaffolds. This study was focused on a hydrogel-seeding method to improve cell adhesion and
proliferation in tubular porous scaffolds for vascular grafts application. Tubular scaffolds were
fabricated from a biodegradable elastic polymer, poly(L-lactide-co-ε-caprolactone) (PLCL) (50:50,
Mn 1.58×105), by an extrusion-particulate leaching method. Vascular smooth muscle cells
(VSMCs) were dispersed in collagen hydrogel and then seeded into the tubular PLCL scaffolds
having various pore sizes, 50-100 μm, 100-200 μm, and 300-500 μm, respectively. As a result, the
efficiency of cell adhesion and proliferation was dependent on the pore size of the scaffolds.
Especially, the cell proliferation efficiency was improved by using the hydrogel-seeding method as
compared with by using a previously established method. In summary, this study demonstrates that
the efficiency of cell adhesion and proliferation was dependent on the pore size of the scaffolds in
the hydrogel-seeding method.
Synthesis of Biodegradable Scaffold from Nano Fibers and Evaluation of Protein Adsorption Behaviors on its Surface
Authors: Ko Jong Hyun , Kim Ji Heung , Chung Dong June
Published: March 2009

The effects of various processing parameters of electro spinning such as concentration,
applied voltage, distance from needle to collector on the morphology(especially fiber diameter) of
nanofiber matrix was investigated in this study. We found out the concentration of polymer solution
was the key parameter to control the fiber diameter. Such a difference on surface morphology of
electro spun nanofiber matrix under various processing parameters will show the different behaviors
on protein adsorption on the surface contacting with body fluid. Consequently, this results different
cell motions on the matrix used on tissue engineering. To evaluate the adsorption of proteins on the
surface of sheet type nanofiber matrix, matrix obtained by electro spinning were immersed in
FITC labeled proteins solutions. And then, we confirmed adsorption of proteins using laser
scanning confocal microscopy (LSCM). The quantitative analysis of adsorbed proteins was also
investigated by UV spectroscopy.
The Effects of Collagen Membrane Coated with PLGA on Bone Regeneration in Rat Calvarial Defects
Authors: Song Kun Young , Um Yoo Jung , Jung Ui Won , Lee Yong Keun , Choi Seong Ho , Kim Chong Kwan
Published: March 2009

The purpose of this study was to evaluate the effects of collagen membrane coated with
PLGA on bone regeneration in rat calvarial defect. Five groups of 10 animals each received either
collagen membrane coated with 0.5%, 1%, 3% concentration of PLGA, collagen membrane only or
surgical control. Each group of animals was healed into 2 healing periods of 2(5 animals) and 8(5
animals)weeks and histologic and histomorphometric analysis were done. The results of the following
study revealed that surgical implantation of collagen membranes coated with PLGA enhanced local
bone formation at both 2 and 8 weeks independent of different PLGA concentrations. In conclusion,
collagen membrane coated with PLGA shows a significant bone formation behavior irrespective of
their concentration.
The Characterization of PLGA/Small Intestinal Submucosa Composites as Scaffolds for Intervertebral Disc
Authors: Kim Soon Hee , Choi Bang Sil , Ko Youn Kyung , Ha Hyun Jung , Yoon Sun Jung , Rhee John M. , Kim Moon Suk , Lee Hai Bang , Khang Gil Son
Published: March 2009

In order to application for the tissue engineered intervertebral disc (IVD), we designed
the synthetic/natural hybrid scaffolds with poly(lactide-co-glycolide) (PLGA) and small intestine
submucosa (SIS). SIS has been widely used as a biomaterial because SIS consists of various
collagens and cytokines. SIS, however, possesses disadvantages such as their weak mechanical
properties and uncontrolled degradation. Novel composite scaffolds of PLGA/SIS were
manufactured by simple immersion method of PLGA scaffolds in SIS solution under vacuum. Then
SIS was crosslinked. Also, PLGA scaffolds and SIS sponges were manufactured by solvent
casting/salt leaching and freeze-dried methods, respectively. We evaluated pore structure, porosity,
water absorption ability and cell viability of three types of scaffolds for the application of IVD.
The Effects of Calcium Phosphate-Chitosan Block Bone Graft on the Periodontal Regeneration in One Wall Intrabony Defects in Beagle Dogs
Authors: Kim Sung Koo , Lee Jung Seok , Chae Gyung Joon , Jung Ui Won , Lee Yong Keun , Kim Chong Kwan , Choi Seong Ho
Published: March 2009

This study evaluated periodontal repair and biomaterial reaction following implantation of
a newly fabricated calcium phosphate chitosan block bone and chitosan membrane on the
regeneration of 1- wall intrabony defects in the beagle dogs. The surgical control group received a flap
operation only, while experimental group was treated with calcium phosphate chitosan block bone
and/or chitosan membrane. All dogs were uneventful healing without any complication. The subjects
were sacrificed 8 weeks after the experimental surgery, and a comparative histological and
histometric examination was done. Chitosan membrane group significantly enhanced bone
regeneration compared to control, CaP-chitosan block bone and combination group. Chitosan
membrane remnants were observed in chitosan and combination group, while CaP-chitosan bone
materials were resorbed completely. These results suggest that Chitosan membrnae significantly
enhanced bone and cementum formation in advanced periodontal defects.
The Double-Layered Microsphere: Encapsulation of Water-Soluble Protein with PLGA
Authors: Ko Jong Tae , Jung Hyung Joon , Mo Jong Hyon , Cho Jae Song , Yuk Soon Hong , Shin Hyung Shik , Kim Moon Suk , Rhee John M. , Lee Hai Bang , Khang Gil Son
Published: March 2009

The double-layered microspheres play an important role in controlling drug delivery for
pharmaceutical application, because of the low initial burst compared with single-layered spheres
and targetable delivery to specific organ. But it has drawback in loading drug and controlling size.
In this study, we developed double-layered spheres using relatively simple oil-in-water (O/W)
solvent evaporation method using bovine serum albumin (BSA) as water-soluble protein and
poly(D,L-lactide-co-glycolide) (PLGA). BSA/PLGA double-layered microspheres were fabricated
using O/W solvent evaporation method and investigated the specific character of double-layered
microspheres according to the kind of surfactants. In SEM observation, double layered microsphere
had spherical shape and smooth surface without pores. And the double layered microsphere using
O/W solvent evaporation method was transparency because of slow evaporation of solvent. In
fluorescent observation, we observed the fluorescent core in the double-walled spheres composed of
FITC-BSA and PLGA using fluorescent observation. In the case of polyvinylalcohol as emulsifier,
the yield was better than gelatin. As decreased concentration of PLGA, the size of double-layered
microspheres deceased.
Long-Circulating, Temperature-Sensitive and EGFR-Targeted Liposomes for Drugs Delivery
Authors: Lim Sun Kyung , Park Heon Joo , Choi Eun Kyung , Kim Jin Seok
Published: March 2009

Effectiveness of epidermal growth factor receptor(EGFR)-targeted, long circulating and
temperature-sensitive liposomes(TSLs) is described using sterically stabilized gemcitabine-loaded
liposomes in vitro. Development of long-circulating formulation of TSLs with the EGFR antibody
attached was designed to expect an increase in binding and drug delivery efficiency to the target
cells such as non-small cell lung cancer cells(A549) and human pancreatic carcinoma cells(PANC-
1). New TSLs were prepared using DPPC:DMPC:DSPC(4:1:1 molar ratio) by the REV method.
Differential scanning calorimetry of TSLs showed the phase-transition around 402. Release of a
self-quenching fluorescent probe, calcein, from TSLs was studied for evaluation of temperaturesensitivity.
Anti-proliferation effect of gemcitabine-loaded TSLs and antibody-conjugated TSLs in
A549 and PANC-1 were higher than free drug. We conclude that sterically stabilized
immunoliposomes exhibited good stability, ability to recognize target cells, and higher potency.
Further studies, including in vivo animal study, are under investigation.
Microstructures and Mechanical Properties of Thermomechanically Processed TiNbSi Alloys for Biomedical Applications
Authors: Kim Won Yong
Published: March 2009

Mechanical properties and elastic modulus were examined in order to clarify the
influence on microstructures in Ti-26Nb-xSi, where x= 0.5, 1 in atomic percent, prepared by arc
melting, cold rolling and recrystallization heat treatment. On the basis of microstructural
observations and phase analyses, it is evidently revealed that the microstructure of as-quenched
sample appeared to mixture appearance consisting of mostly bcc-structured β phase and small
amount of orthorhombic-structured α″ phase. Elongated structure parallel to the rolling direction
was observed in cold rolled samples, and equiaxed structure with the average grain size of about
20μm was developed for the sample after recrystallization heat treatment. Randomly distributed
feature of pole figure was characterized without showing a specific texture component in asquenched
sample. Rotated cube, α-fiber and γ-fiber texture components were detected in cold-rolled
sample. After recrystallization heat treatment the intensity of α-fiber texture component was
markedly decreased, while the rotated cube component becomes sharpened and γ-fiber component
remains relatively unchanged. From both elastic modulus and strength point of view
recrystallization treatment would be desirable to meet the required mechanical properties of the
present alloys for biomedical applications.
A Study on the Effect of Grain Size on the Bioactivity of Nano-Titania Ceramics
Authors: Yu Qi Feng , Li Zhen Sheng , Yang Bang Cheng , Huang Y. , Gan L. , Qu Yang , Zhang Xing Dong
Published: March 2009

Nano-titania ceramics is a potential biomaterial for orthopaedic application. In our
previous studies, a bioactive nano-titania ceramics was prepared by using alkali-heat treatment. In
this paper, hydroxyapatite was used as a grain growth inhibitor additive to get nano-titania ceramics
with different grain size, and the effect of grain size on the bioactivity was studied in vitro.
Stability Changes of Dental Implants According to the Simulated Peri-Implant Bone Defects
Authors: Park Chan Jin , Lee Mi Ran , Cho Lee Ra , Yi Yang Jin , Jung Ho Nyun
Published: March 2009

Twenty implants of 3.75mm in diameter(Neoplant, Neobiotech, Korea) were used to evaluate the
correlation between the resonance frequency analysis (RFA) and the radiographic method for periimplant
bone change under in vitro conditions. To simulate peri-implant bone change, 2mm-deep
45° range horizontal defect and 2mm-deep 90° range horizontal defect area were serially prepared
perpendicular to the X-ray beam after conventional implant insertion. ISQ values and gray values
inside threads were measured before and after peri-implant bone defect preparation. ISQ value of
resonance frequency analysis was changed according to peri-implant bone change and gray value of
radiographic method was changed according to peri-implant bone change. In horizontal defect
condition, relatively positive correlation were between ISQ and gray values(r=0.663).
Approximation of the Kinematics of Foot Joints by Using Passive Elastic Characteristics of Joint
Authors: Choi Hyeon Ki , Kim Si Yeol , Cho Won Hak
Published: March 2009

We investigated the relationship between kinematic and kinetic characteristics of foot
joints resisting ground reaction force (GRF). Passive elastic characteristics of joint were obtained
from the experiment using three cameras and one force plate. The relationship between joint angle
and moment was mathematically modeled by using least square method. The calculated ranges of
motion were 7o for TM joint, 4o for TT joint and 20o for MP joint. With the model that relates joint
angle and plantar pressure, we could get the kinematic data of the joints which are not available
from conventional motion analysis. The model can be used not only for biomechanical analysis
which simulates gait but also for the clinical evaluations.
Preparation of Biologically Derived Hydroxyapatite and its Dissolution
Authors: Seo Dong Seok , Kim Hwan , Lee Jong Kook
Published: March 2009

Hydroxyapatite derived from human teeth was sintered at 1200°C for 2 h. Dissolving
behavior of the biologically derived HA (BHA) in distilled water was investigated and compared
with an artificial hydroxyapatite (HA) made of synthetic HA powder. All disks were immersed in
40 ml of pH 7.4 distilled water (buffered using 0.05 M Tris.) for 7 and 14 days at 37°C. All
detectable peaks in the HA are identical only to HA lattice planes, whereas BHA consisted of a
mixture of HA and β-tricalcium phosphate (TCP). In the case of the HA specimen, the surface
dissolution was initiated at grain boundaries followed by generated many separated grains and large
defect like cavities. On the other hand, biologically derived HA showed that definite grains
considered as β-TCP was predominantly dissolved and the grains were separated from the matrix
leaving pores. In the mean time, the rest region, mainly consisting of HA, did not show any
evidence of dissolution. It seems that BHA is more stable than the artificial HA in liquid
environment.
Effects of Thin Hydroxyapatite Coating on Initial Response of Osteoblast-Like Cells
Authors: Kwon Un Hye , Kam Min Hee , Bachle Maria , Kim Dae Joon , Lee Won Jun , Kim Hye Lee , Han Jung Suk
Published: March 2009

To combine the bioinert titanium with the biological active coating of hydroxyapatite
[HA, Ca10(PO4)6(OH)2] a new pulsed laser deposition(PLD) method was applied. The initial
osteoblast-like MC3T3-E1 cell response to this thin HA coated(<1μm) surface was compared with
non-coated surfaces. Cell responses on four different pure titanium surfaces, such as smooth
titanium, HA coated smooth titanium, rough titanium and HA coated rough titanium, were
compared. Cell morphology and attachment were examined by scanning electron microscopy after
6, 24 and 72 hrs of culture, cell proliferation by MTS assay after 3, 7 and 14 days. The
differentiation of the cells was analyzed by real time PCR up to 21 days. The cells were well spread
and attached on all surfaces and showed more irregular shapes on the HA coated specimens. They
proliferated continuously on all specimens up to 14 days. Smooth surface specimens showed better
cell proliferation than rough ones after 7 days, and the HA coated specimens demonstrated slightly
greater MTS activity than the non-coated groups after 14 days. The surface topography affected cell
proliferation initially however; there was no significant difference afterwards. Thin HA coating
influenced the expression of some genes related with cell differentiation.
Biomechanical Approach of Radius of Curvature on the UHMWPE Core in Artificial Intervertebral Disc Using FE Analysis
Authors: Kim Cheol Woong , Kang Bong Su , Oh Dong Joon
Published: March 2009

The research of 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 curvature of
the sliding core is also suggested.
Synthesis and Properties of Thermotropic Main-Chain Type Liquid Crystalline Polyurethanes Containing Biphenyl Mesogen
Authors: Lee Jong Baek , Kang Byung Won
Published: March 2009

A new type of thermotropic main-chain liquid crystalline polyurethanes containing
biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene
diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate,
with 4,4′-Bis(8-hydroxyoctoxy)biphenyl (BP8). The structure of the monomer and the
corresponding polymers were confirmed using FT-IR and 1H-NMR spectroscopic methods. BP8
exhibited a smectic type mesophase, however, nematic phases were found for all synthesized liquid
crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP8 based polyurethane. For
example, polyurethane 2,5-TDI/BP8 exhibited monotropic liquid crystallinity in the temperature
ranging from 172 to 160 °C on the cooling stage. Properties of these polyurethanes were studied by
differential scanning calorimetry (DSC), and optical polarizing microscopy. The FT-IR study
indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism.
Effect of Different Hydroxyapatite Particles on Malignant Melanoma Cell Behavior
Authors: Guo B. , Li B. , Wang Xin Long , Tang L. , Chen Q.Y. , Zhang Xing Dong
Published: March 2009

The effect of different hydroxyapatite particles on malignant melanoma cell was
evaluated in vitro. Two kinds of short-rode hydroxyapatite particles, which range from 0.4 to 1 um
and 0.5 to 1.5 um, were co-cultured with human’s malignant melanoma (MM) cell line A375 for 24,
48, and 72 h. Both of these HA particles showed the same cell proliferation rate as blank control,
and there was no statistically significant correlation of matrix metalloproteinases-2 (MMP-2)
expression to the HA particle size. SEM images showed that the membrane of tumor cell, which
co-cultured with HA particles, was shrunk. The cell superficial sentus was reduced and small size
particle’ effect was more obvious. Since immunohistochemistry and SEM data are qualitative
technique, further precise methods might bring more information about the effect of HA particles on
tumor behaviors. But this study can provide the bio-security test of micrometer HA particles in
transplantation after tumor excision.
Degradation Control of Collagen by Epigallocatechin-3-O-Gallate
Authors: Cho Han Hee , Matsumura Kazuaki , Nakajima Naoki , Han Dong Wook , Tsutsumi Sadami , Hyon Suong Hyu
Published: March 2009

Stabilization of the fibrous protein collagen is important in biomedical applications. This
study investigated the efficacy of degradation control of collagen using (-)-epigallocatechin-3-Ogallate
(EGCG). EGCG treatment of collagen in solid state was carried out and collagen sponges
produced were characterized by measuring the physicochemical properties such as gel fraction, the
enzymatic degradability and cytocompatibility. According to gel fraction, EGCG-treated sponges
showed the increase of insolubility compared to intact sponges. It showed that EGCG played a role
in a crosslinker of collagen. Through in vitro enzymatic degradation test, EGCG-treated collagen
sponges showed significant enhancement of resistance to collagenase in comparison with 25 mM
EDC-treated collagen sponges. Also, cell proliferation assays showed that 40 mM EGCG-treated
collagen sponges exhibited similar cytocompatibility properties compared with tissue culture plate.
In summary, EGCG treatment of collagen sponges increased the stability of collagen. Therefore,
crosslinking of collagen based scaffold with EGCG imparted more desirable properties, making it
more applicable for use as a scaffold in tissue engineering applications.
Improvement and FEA of New Type of Osteointegrated Implant for Higher Amputated Leg Attachment
Authors: Luo J.M. , Zheng L. , Shi X.H. , Wu Yao , Zhang Xing Dong
Published: March 2009

Stress concentration is one of the main mechanical problems leading to the failure of
clinical application for osteointegrated implant of percutaneous osteointegrated prosthesis, which is
especially marked for higher amputated leg prosthesis. Traditionally design was composed of only
the distal part. To improve the biomechanical safety, a new design with the lag part similar to the
lag screw was introduced. Based on CT scan data, relatively accurate model of femur for finite
element analysis (FEA) were obtained. The FEA results with the new implant demonstrated that
compared to traditional design, the declination of bone stress peak ranged from 15.68% to 28.67%,
perpendicular deformation from 34.73% to 72.16%, and maximal stress of implant from 14.51% to
23.36% with the increasing of loads from 3750N to 2000N. So the new design of osteointegrated
implant would be more secure mechanically, in the case of higher amputated leg attachment.
Biological Evaluation of Sirolimus-Loaded PLGA Films
Authors: Ren Ling , Wang Jin , Tang Jia Ju , Pang Ch.J. , Maitz M. , Huang Nan
Published: March 2009

Sirolimus-loaded poly (lactic acid-co-glycol acid) (PLGA) films were prepared by a
casting method. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was
performed to determine the optimal concentration of sirolimus for vascular smooth muscle cell
(VSMC) inhibition effect. Based on the results of MTT, three samples of different weight percent
loaded-sirolimus (2wt%, 6wt%, 15wt%) PLGA films were selected. The release of lactate
dehydrogenase (LDH) was used to evaluate the immediate toxicity of the sirolimus-loaded PLGA
films and it was shown that the three different concentrations of sirolimus-loaded films have low
toxicity. Alamar blue results indicate that the sirolimus-loaded films have better antiproliferation
effect than 316 stainless steel (SS). The higher the sirolimus concentration in the film is, the better is
the antiproliferation effect. These films may be used for stent coating to inhibit in-stent restenosis
induced by VSMC proliferation.
In Vivo and In Vitro Tendon Engineering
Authors: Xu Feng , Liu Wei , Wei Xian , Li Hong , Cao De Jun , Cao Yi Lin
Published: March 2009

Tendon is an important supportive tissue of human body responsible for normal physical
activity. However, tendon damage and defect remain an important factor for causing disability. The
rise of tissue engineering technology provides an effective means of tendon reconstruction and
repair, which will bring promise for functional recovery. In our center, tendon engineering is one of
major research areas. We have performed the in vivo study by using tenocytes and polyglycolic acid
fibers to reconstruct and repair tendon defect in hen and porcine models. The results demonstrated
the successful regeneration and repair of tendon defects created in different models. In addition,
tendon function was also well recovered by generated autologous tendon tissue that possesses strong
biomechanical property. Recently, we have also successfully generated tendon tissue in vitro by
using static strain device and bioreactors, which could be potentially transplanted as the tendon graft
for tendon defect repair.
Changes in Intradiscal Pressures due to More Compliant Spinal Stabilization System
Authors: Ahn Y.H. , Lee H.S. , Chen Wen Ming , Park K.W. , Ryu G.U. , Lee Sung Jae
Published: March 2009

Dynamic stabilization of the lumbar spine has gained increasingly popularity. These
nonfusion systems are alleged to maintain or restore the intradiscal pressure to magnitudes of the
intact spine and have little negative effect on the adjacent segments to the stabilized one. Compliant
Nitinol alloy (Ni-Ti) has been used in the manufacture of the rods of the dynamic stabilization
systems. In this study, we investigated a dynamic stabilization system with its coiled rods made of
Nitinol alloy. Four porcine lumbar spines (T12-L6) were prepared: intact, fixed by a conventional
rigid fixation system, fixed by a dynamic stabilization system with 2-coiled rods, fixed by a
dynamic stabilization system with 3-coiled rods. Intradiscal pressures were measured at all levels
before and after insertion of the implant. Our results show that the rigid stabilization system resulted
in great changes of disc pressure in flexion and extension regardless of spinal levels. However,
Intradiscal pressures (IDPs) remained relatively unchanged in models fixed by the dynamic
stabilization systems. Changes in intradiscal pressure can lead to altered metabolism within the disc,
with potential long-term disc degeneration. These results suggest that the dynamic stabilization
systems are superior over traditional fusion implants in maintaining the intradiscal pressure to the
intact level at surgical level and adjacent level and can therefore be considered as an alternative
method to fusion surgery in these indications while the intradical pressure is preserved.
Latest Developments in Sheet Metal Forming Technologies and Materials for Automotive Application: the Use of Ultra High Strength Steels at Fiat to Reach Weight Reduction at Sustainable Costs
Authors: Lai Manuel , Brun R
Published: March 2009

In new vehicles development weight reduction is one of the most important driving force
often conflicting with other missions which would require additional mass (crashworthiness,
comfort, etc). The use of HSS, especially new grades with very high strength and good formability
is the most competitive way to reduce weight. Nevertheless some limitations come from
manufacturing HSS: springback, residual stresses, weldability should be taken into account in
product development in order to avoid an expensive set up phase in the press shop and in the body
shop. This paper focus on the recent experience achieved by Fiat in introducing HSS up to reach a
share higher than 60% in weight applying and developing new methodologies to solve in the design
phase any criticality arising from the use of this material.
An Application of Neural Network Solutions to Modeling of Diode Laser Assisted Forming Process of AA6082 Thin Sheets
Authors: Guarino S. , Ucciardello Nadia , Tagliaferri Vincenzo
Published: March 2009

In this paper a neural network approach is used to model the diode laser assisted forming
process. In particular thin sheets of Aluminum alloy AA 6082 were bended in the elastic range and
then treated with a diode laser with the aim to reduce the spring back phenomenon. Experimental
tests were performed to study the influence of the process parameters such as laser power, laser
speed and starting elastic deformation on the evolution of forming process. In particular the heating
effects on the elastic properties of the material was studied. A statistical approach is used to define
the experimental plan and discuss the experimental results. Interesting trend of the effects of the
diode laser on the forming process were found. Subsequently in order to predict the residual
inflexion, during the laser forming, a multilayer feedforward artificial neural network has been
implemented. A sensitivity analysis on the artificial neural network model is used to show the
significance of all the input data employed. As a result of sensitivity analysis, a check between
experimental and calculated trends for each investigated variables was performed, which revealed
an appreciable fit between data displayed.
System Development of Micro Gas Turbine Co-Generation
Authors: Hur Kwang Beom , Rhim Sang Kyu , Park Jung Keuk , Kim Jae Hoon
Published: March 2009

The new market penetration using the distributed generation technology is linked to a large
number of factors like economics and performance, safety and reliability, market regulations,
environmental issues, or grid connection standards. KEPCO, a government company in Korea, has
performed the project to identify and evaluate the performance of Micro Gas Turbine (MGT)
technologies focused on 30, 60kW-class grid-connected optimization and combined Heat & Power
performance. This paper describes the results for the mechanical, electrical, and environmental tests
of MGT on actual grid-connection under Korean regulations. As one of the achievements, the
simulation model of Exhaust-gas Absorption Chiller was developed, so that it will be able to analyze
or propose new distributed generation system using MGT.
Corrosion Fatigue Crack Propagation Characteristics of TMCP Steel in Synthetic Seawater Condition under Wave Period
Authors: Kim Won Beom , Paik Jeom Kee
Published: March 2009

In this research, corrosion fatigue tests using 490MPa TMCP steel were performed in
synthetic seawater condition to investigate the corrosion fatigue crack propagation characteristics of
TMCP steel plate which is often used for ships and offshore structures from its weldability and weight
reduction purpose. In addition, relationships between boundary correlation factor F(α,β) and α(=
2a/W) of the fracture mechanics formula for the test specimen which was exerted by the pin load were
calculated for the evaluation of da/dN-.K. To get the boundary correlation factor F(α,β), the
calculation of J as a path-independent line integral was carried out. The solutions of J integral showed
similar value in spite of the different path. Crack propagation tests for the same steel in air condition
was carried out also for comparison. Finally, it was clear from the crack propagation test results that
the propagation rate of TMCP steel plate in synthetic seawater condition is faster than that of in air
condition at least twice.