bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Hole Flangeability of Steel Sheet with Respect to the Hole Processing Condition
Authors: Lee Jong Sup , Ko Yoon Ki , Huh Hoon , Kim Hong Ki , Park Sung Ho
Published: March 2009

This paper is concerned with hole flangeability of steel sheet, which is evaluated by
experiment and finite element analysis with respect to the hole processing condition. The hole
flangeability of a material as a forming limit needs to be verified to predict and prevent the
undesirable fracture during a flanging process. Hole expanding tests are carried out to identify the
effect of hole processing conditions on the hole expanding ratio (HER), which is an indicator of the
hole flangeability. Specimens with two different hole conditions are prepared: one is produced with
punching process; and the other is reamed after punching to get smoother hole surface. Experimental
results show that the facture mechanism and the HER are quite different with respect to the hole
conditions. Thorough investigation of those effects is carried out with tensile tests of a specimen with
notches. From the experiments, the fracture strain is obtained with different hole conditions and is
used to determine the material constants of a new proposed ductile fracture criterion which is applied
to finite element analyses of the hole flanging process for prediction of the HER. The experimental
results are confirmed and reevaluated by the finite element analysis with the ductile fracture criterion.
Pass Schedule of Wet-Wire Drawing Process with Ultra High Speed for Tire Steel Cord
Authors: Lee Sang Kon , Hwang Won Ho , Ko Dae Cheol , Kim Byung Min , Ko Woo Sik
Published: March 2009

High speed multi pass wet wire drawing has become very common for production of high
carbon steel cord because of the increase in customer demand and production rates in real industrial
fields. Although the wet wire drawing is preformed at a high speed usually above 1000 m/min, greater
speed is required to improve productivity. However, in the high carbon steel wire drawing, the wire
temperature rises greatly as the drawing speed increase. The excessive temperature rise makes the
wire more brittle and finally leads to wire breaks. In this study, the variations in wire temperature
during wet wire drawing process were investigated. A multi pass wet wire drawing process with 21
passes, which was used to produce steel cord, was redesigned by considering the increase in
temperature. Through a wet wire drawing experiment, it was possible to increase the maximum final
speed from 1000 m/min to 2000 m/min.
On-Line Optimization of Coiling Temperature Control on Run-Out Table for Hot Strip Mills
Authors: Xie Hai Bo , Jiang Zheng Yi , Liu Xianghua , Wang Guo Dong , Zhou Tian Guo , Tieu A. Kiet
Published: March 2009

Based on optimization setup technology, an online adaptive calculation method for
improving accuracy of strip coiling temperature control on the run-out table (ROT) has been
developed and implemented in hot strip mill (HSM). Multi-objective control strategies, which
include coiling temperature, middle target temperature and appropriate cooling rates have been
finalised. Cooling strategies, elements tracking, and dynamic correction are employed in the control
system. In addition, the model optimization and soft-measure method are also introduced in the
study. Rolling tests with various grades of steel covering a wide range of thickness show that the
developed model can improve the accuracy of coiling temperature control to obtain an uniform
mechanical properties. Good correlation has been found between the predicted temperatures and the
actual coiling ones.
Web Based Shape Inspection System for the Forging Products Having Complicated Shapes
Authors: Park K.S. , Kim B.J. , Kim D.W. , Moon Young Hoon
Published: March 2009

The outer race of the constant velocity(CV) joint is an important load-supporting
automotive part, which transmits torque between the transmission and the wheel. The outer race is
difficult to be forged, because its shape is very complex and the required dimensional tolerances are
very stringent. Therefore, the internet based shape inspection system is developed in this study to
provide quick and accurate measuring data. Proposed system uses mechanical displacement sensors
to measure the shape of CV joint that has six inner ball grooves, and commercially available Lab-
View program is used to process measured data into the dimensional shape. Developed program
provides a simple user interface that enables users to have real-time access of data measured from
industrial production lines. Furthermore, the measured data can be exchanged via the internet
between users and forging system operators. A java applet helped the system connection via
internet. A data, IP access, is transmitted to the packet by TCP/IP. Our proposed system has many
advantages over current measuring systems including fast and efficient data processing by real-time
measuring, and system flexibility.
Reduction of Stages in Multi-Stage Metal Forming Process Based on Numerical Optimization in Conjunction with FE Simulation
Authors: Hino Ryutaro , Sasaki Akihiko , Yoshida Fusahito , Toropov Vassili V.
Published: March 2009

In this study, a new simulation-based design technique for multi-stage metal forming
process is developed with special emphasis on reduction of stages in the process. The developed
design technique is an iterative design optimization, which is based on response-surface-based
numerical optimization and finite element analysis of the process. The design procedure starts with
the initial rough process design. To eliminate one stage in the multi-stage process, the new optimum
process design is determined based on the former process design by using numerical optimization in
conjunction with FE simulation. This design optimization step is repeated, reducing the stages one by
one, until the possible minimum number of stages is reached. The developed design technique is
applied to stage reduction of a 3-stage axisymmetric forging process of aluminum billet. We can
confirm that a new 2-stage process design is determined successfully and the developed design
optimization technique is effective to reduce stages in multi-stage forming process.
Calibration of Texture-Adjusted Strain-Rate Potential and its Application
Authors: Chen Yi Ping , Lee Wing Bun , To Sandy
Published: March 2009

An accurate prediction of plastic anisotropy induced by initial texture in sheet metal
forming operations depends on the constitutive models adopted. Models of engineering interest
include both phenomenological formulations and crystal plasticity based on dislocation slip. In
addition to the above two approaches that are commonly adopted in FE analysis, now an alternative
is available which describes anisotropic behavior of polycrystalline sheet metals still by an analytic
yield function to keep the computing time as low as possible but at the same time which also takes
explicitly into account the crystallographic texture of the material to give a more precise description
of plasticity anisotropy. However, the locus of such a yielding potential determined by constitutive
coefficients upon invoking the rate-independent crystal plasticity may exhibit an unrealistic
concave shape, which will make it impossible to obtain a convergent solution. To circumvent the
difficulty, a detailed computation procedure is presented to calculate the constitutive coefficients
based on rate-dependent crystal plasticity. The combination of the coefficients obtained with
experimentally measured texture coefficients of an annealed FCC polycrystalline sheet metal will
provide a complete constitutive characterization of the material. As an application of the calibrated
model, the process of deep drawing by hemispherical punch is simulated, in which plastic
anisotropy (earring) corresponding to typical texture type is observed, thus demonstrating the
applicability of the coefficients found.
Plastic Deformation Behavior of High Strength Steel Sheet under Non-Proportional Loading and its Modeling
Authors: Uemori Takeshi , Kuramitsu T. , Hino Ryutaro , Naka Tetsuo , Yoshida Fusahito
Published: March 2009

This paper deals with experimental observations and modeling of plastic deformations of
a high strength steel sheet (HSS sheet) under biaxial stress conditions. Using a cruciform specimen
of a HSS sheet of 980MPa-TS, experiments of proportional and non-proportional loadings were
performed. Numerical simulations for the biaxial stress-strain responses were conducted using a
constitutive model of large-strain cyclic plasticity (Yoshida-Uemori model), and the results were
compared to the experimental data. The results of numerical simulation show a good agreement
with the experimental results, which is attributed to accurate modeling of the backstress evolution
of the anisotropic yield surface.
Molecular Dynamics Simulation on Crack Initiation at Bi-Material Interface Edges
Authors: Shang Fu Lin , Kitamura Takayuki
Published: March 2009

Molecular dynamics (MD) simulations are performed to study the onset of fracture at the
free edges of bi-material interfaces. The objective is to see whether a unified criterion could be
formulated for crack initiation at interface edges with different angles or not. The simulations are
facilitated with model bi-material systems interacting with Morse pair potentials. Three simulation
models are considered, i.e. the interface edges with angles 45°, 90° and 135°, respectively. The
simulation results show that, at the instant of crack initiation, the maximum stresses along the
interfaces reach the ideal strength of the interface; also, the interface energies just decrease to below
the value of the intrinsic cohesive energy of the interface. These findings revealed that the onset of
fracture at the interface edges with different geometries could be controlled by the maximum stresses
or the cohesive interfacial energy.
Reconstruction of Kidney-Like Tissue Using ECM Gel and Rat Embryonic Kidney Fragments
Authors: Zhu Ying Jian , Liu Wei , Zhang Wen Jie , Zhou Guang Dong , Liu Guo Hua , Cao Yi Lin
Published: March 2009

Organ engineering remains a challenge to researchers. We tried to reconstruct kidney-like tissue
using tissue engineering technique. Kidney fragments were isolated from rat E16 embryonic
kidneys and seeded on either ECM gel or on polyglycolic acid (PGA) fibers, then implanted in vivo
into the subcutaneous tissue of nude mice for 2 and 3 weeks, respectively. As a negative control,
ECM alone was implanted. Results showed that kidney like tissue could be formed in ECMfragment
constructs after 2 or 3 weeks of implantation, including the formation of glomeruli,
tubules and collecting ducts. In addition, these structures seemed more mature in 3 weeks
specimens than that of 2 weeks. Further development of this model may lay a solid foundation for
kidney tissue engineering.
Comparison of Mammalian Cell Suspension Culture Methods Using Poly(lactic-co-glycolic acid) Nanospheres and Dextran Microcarriers
Authors: Ryu Ju Hee , Kim Byoung Soo
Published: March 2009

Previously, we have developed a novel method for suspension culture of anchoragedependent
animal cells using biodegradable polymer nanospheres. In this study, we compared the
polymer nanosphere culture method to dextran microcarrier culture method, which is a conventional
suspension culture method. Most of human dermal fibroblasts (91 ± 5 %) cultured with polymer
nanospheres formed aggregates on day 2. Most of cells (92 ± 7 %) attached onto microcarriers by 4
h. Microcarrier culture method had a lower apoptotic activity (3.4 folds on day 4), compared to the
nanosphere culture. The microcarrier culture method had a higher cell growth (2.4-fold versus 1.7-
fold growth on day 4) than the nanosphere culture. Although the polymer nanosphere culture
method did not yield better outcomes than the microcarrier culture, the polymer nanosphere culture
method may offer advantages over the microcarrier culture method with respect to cell protection
from the shear stress during agitation at high speed and cell transplantation without enzyme
digestion process to harvest cultured cells.
RGD Direct Conjugation Using Co-Solvent System to Increase Cell Attachment on Poly(lactide-co-glycolide) without Change in Hydrophilic/Hydrophobic Property
Authors: Lee Soo Hong , Chung Hyung Min , Kim Young Ha , Kim Soo Hyun
Published: March 2009

We have developed a direct conjugation method of RGD (Arg-Gly-Asp) into polylactide
(PLA) using co-solvent system, which showed high reaction yield compared to one solvent system
presumably due to good solubility of reactants. First, hydroxyl groups at the end of PLA were
changed into carboxyl acid by ring opening reaction of succinic anhydride. For a coupling reaction
with high solubility, RGD was dissolved in water and then PLA in dioxane was added into RGD
solution in the presence of 1-(3-dimenthylaminopropyl)3-ethylcarbodiimide hydrochloride (EDC).
The conjugation of RGD was confirmed by 1H-NMR, GPC and elementary analysis. The RGD
conjugated PLA (RGD-PLA) on poly(lactide-co-glycolide) (PLGA) film significantly increased the
number of attached cells compared to PLGA without RGD-PLA, while it did not change static
contact angle of PLGA. This result demonstrated this conjugation method would be a useful tool to
increase cell affinity of biomaterials without change in hydrophilic/hydrophobic property for tissue
engineering applications.
Effect of DBP/PLGA Hybrid Scaffold on Angiogenesis during the Repair of Calvarial Bone Defect
Authors: Yoon Sun Jung , Park Ki Suk , Choi Bang Sil , Khang Gil Son , Kim Moon Suk , Rhee John M. , Lee Hai Bang
Published: March 2009

This study was designed to investigate the influence of demineralized bone particles
(DBP)/PLGA hybrid scaffold on angiogenesis and osteogenesis in a calvarial defect model.
DBP/PLGA scaffolds were manufactured by solvent casting/salt leaching method, and each scaffold
contained 0, 10, 20, 40, and 80 wt% DBP of PLGA, respectively. A total of 34 rats were operated
and bicortical holes were placed on their calvaria. The defects were filled with different ratio
DBP/PLGA scaffolds. After 3, 7, 14, and 28 days, specimens were taken and, histologic,
immunohistologic and RT-PCR analyses were carried out concerning number of vessels and density
of regenerated bone, and angiogenic activation. On days 7, in all experimental groups, bone
formation occurred in a direction from defected margin of calvarium to center of implanted scaffold
and new vessel formation took place in front of the osteogenic regeneration front. We found that the
20 and 40 wt% DBP/PLGA scaffold was superior in its ability to regenerate new bone, induced
more intensive formation of microvasculature and expressed in a higher level of osteocalcin mRNA
than other groups.
Hybrid Type of Tissue Engineered Biodisc Using Annulus Fibrosus Seeded PLGA Scaffold and Nucleus Pulposus Seeded MPEG-PCL Hydrogel: Preliminary Study
Authors: Ko Youn Kyung , Kim Soon Hee , Ha Hyun Jung , Yoon Sun Jung , Rhee John M. , Kim Moon Suk , Lee Hai Bang , Khang Gil Son
Published: March 2009

Recently, it has been studied tissue engineered technique as novel approaches for
treatment of the degenerative intervertebral disc (IVD). We designed the hybrid type of IVD
mimicked scaffolds with poly(lactide-co-glycolide) (PLGA) and methoxypoly(ethyleneglycol)-
poly(-caprolactone) (MPEG-PCL) diblock copolymers in order to application for the tissue
engineered IVD. The MPEG-PCL solutions formed a gel-to-sol phase transitions as the temperature
was increasesd. MPEG-PCL diblock copolymers were prepared by ring opening polymerization,
and then nucleus pulposus (NP) cell was impregnated. Also, in order to restore annulus fibrosus
(AF), we fabricated PLGA scaffold by solvent casting/salt leaching method. We confirmed disc cell
function in manufactured scaffold through MTT assay in vitro and gross morphology and special
staining in vivo for the possibility of the application of tissue engineering techniques.
Development of Efficient Cardiac Differentiation Method of Mouse Embryonic Stem Cells
Authors: Hong S. , Kang J.K. , Bae C.J. , Ryu E.S. , Lee S.H. , Lee J.H.
Published: March 2009

To obtain an enhanced population of cardiomyocytes from differentiating mouse
embryonic stem (ES) cells, we confirmed the role of noggin treatment during the cardiac
differentiation of mouse ES cells. ES cells were cultured in ES medium containing both noggin and
LIF for 3 days on the mouse embryonic fibroblast feeder layer, followed by dissociated and
suspension culture without LIF to form the embryoid body (EB). The next day, noggin was
eliminated and EBs were cultured continuously. Noggin treated ES cells showed a relatively rapid
increase of cardiac marker genes, while the vehicle (PBS) treated group showed no significant
cardiac marker expression at 4 days after the EB formation. Furthermore, Noggin treated ES cells
showed 68.00±9.16% spontaneous beating EBs at 12 days after the EB formation. To develop a
more efficient cardiomyocyte differentiation method, we tested several known cardiogenic reagents
(ascorbic acid, 5’-Azacytidine, LiCl, oxytocin, FGF2 and PDGF-BB) after noggin induction or we
cultured noggin treated ES cells on various extracellular matrixes (collagen, fibronectin and
Matrigel). Quantitative RT-PCR and immunocytochemistry results showed a significantly increased
cardiac differentiation rate in the FGF2 treated group. Differentiation on the collagen extracellular
matrix (ECM) could slightly increase the cardiac differentiation efficiency. These results show the
possibilities for the establishment of selective differentiation conditions for the cardiac
differentiation of mouse ES cells.
Muscle-Derived Stem Cell/Polymer Hybrid Mixture for the Treatment of Urinary Incontinence
Authors: Oh Se Heang , Kim Jun Ho , Lee Ji Youl , Ghil Sung Ho , Yuk Soon Hong , Lee Jin Ho
Published: March 2009

In this study, muscle-derived stem cell (MDSC)/Pluronics/polycaprolactone (PCL)
microparticle hybrid mixture was prepared as a potential injectable urethral bulking agent for the
treatment of urinary incontinence. The MDSCs were isolated from the gastrocnemius muscles of
SD rats by a modified preplate method and characterized through FACS analysis using various
primary antibodies (CD34, Sca-1, CD45 and desmin). The hybrid mixture was prepared by the
mixing of PCL microparticles (diameter, 100~200 μm) and MDSCs-containing thermo-sensitive
Pluronic (F127/F68 mixture) solution (4.5/5.5, w/v). The hybrid mixture was easily injected
through 18G needle into the body and stably remained in the applied site without initial volume
decrease, owing to a well-packed structure of PCL particles exhibited in the hybrid mixture. It was
observed that the MDSCs were stably grown in the hybrid mixture without severe inflammation and
immune reaction. From the results, we recognized that the hybrid mixture can be a good candidate
as an injectable bulking agent for the treatment of urinary incontinence, due to their good
injectability, volume retention and biocompatibility.
In Vitro Studies of Macrophage Biological Behavior on Cardiovascular Biomaterials
Authors: Zhao An Sha , Li Gui Cai , Yang Ping , Leng Yong Xiang , Chen Jun Ying , Wang Jin , Wan Guo Jiang , Huang Nan
Published: March 2009

Macrophages play a critical role in inflammatory response to implanted biomaterials and
formation of restenosis. Macrophage adhesion may lead to macrophage activation and smooth
muscle cell proliferation. Titanium oxide films on stainless steel are potential biomaterials for
application to vascular stents. They have different influences on smooth muscle cell proliferation in
in vivo tests, which could be the main reason for restenosis, but the mechanism is not clear. In this
study we show that titanium oxide films can reduce inflammatory reaction with macrophages.
Unstimulated macrophages release small amounts of chemical substance such as NO and give slight
effect on smooth muscle cell proliferation.
Properties of Sterilized Human Skin Allografts by Gamma-Irradiation
Authors: Kang Nak Heon , Kim Jin Young , Ahn Jae Hyoung , Song Seok Beom , Seo Seog Jin , Chae Ji Hwa , Kim Tae Woon , Lee Kwang Won , Kim Jin , Cho Chong Su , Kang Ke Won
Published: March 2009

The most commonly used sterilization method of human skin allografts is ethylene oxide
(EO). EO gas, however, can change the biomechanical properties of the grafts and produce toxic
residues which are harmful to the recipient. The heating method cannot be applied for sterilization
of soft tissues because of damage due to heat. The purpose of this study was to determine whether it
is possible to apply gamma-irradiation for sterilization of soft tissues as well as for hard tissues.
Effect of (1→3)(1→6)-Β-Glucan Containing PLGA Scaffold on Human Dermal Fibroblast Attachment and Proliferation
Authors: Lee Sang Gil , Lee Jung Bok , Park Jong Chul , Yang Young Il , Kim Jeong Koo
Published: March 2009

The effect of β-glucan-reinforced PLGA scaffold on cell proliferation was investigated.
The PLGA scaffolds were prepared by salt-leaching method. The prepared scaffolds were grafted
with (1→3) (1→6)-β-glucan in various ratios after plasma treatment on the surface. The surface of
the scaffold was characterized by scanning electron microscope (SEM). The HDFs (Human dermal
fibroblasts, 1105 cells/scaffold) were used to evaluate the cell proliferation on PLGA scaffold
before and after plasma/β-glucan treatment. In results, in the β-glucan treated scaffolds, the pores
seemed to become narrower and even looked like closed form. The result of cell proliferation
showed that the plasma/β-glucan treated scaffolds had narrower pores because the β-glucan was
attached in the pores that would not be allowed the cells to penetrate into the inner areas.
Consequently, cell proliferation was not effective in the plasma/β-glucan treated scaffolds in this
study.
A Tissue Engineering Based Approach to Regeneration of Intervertebral Disc
Authors: Lee Y.J. , Kim I.A. , Park S.A. , Shin W.J. , Kim C.W. , Bae J.W. , Park Ki Dong , Shin Jung Woog
Published: March 2009

Thermosensitive scaffold was suggested for the partial replacement of nucleus in
degenerated intervertebral disc with a minimally invasive surgical procedure. Biocompatible and
thermosensitive scaffolds were prepared by coupling reaction of Pluronic with chitosan and it was
inserted in degenerative spinal motion segments. To confirm the regeneration of degenerative discs
and subsequent structural stability, cell proliferation and morphological changes were evaluated
using relaxation time, quantity of DNA and histological examination. As a result, inserted group
showed higher relaxation time, reduced the decrement of DNA contents, and accumulated GAG
amount. The results confirmed the potential of thermosensitive scaffolds and minimally invasive
surgical procedure for the regeneration of degenerative discs.
Preparation and Release Profile of BDNF-Loaded PLGA/SIS Scaffold
Authors: Shin Yu Na , Cho Mi Hee , Ahn Hyun Hee , Kim Moon Suk , Ghang Gil Son , Lee Hai Bang
Published: March 2009

The goal of this study was to investigate release tendency of brain-derived neurotrophic
factor (BDNF) from poly(L-lactide-co-glycolide) (PLGA) and small intestine submucosa (SIS)
scaffold prepared by ice-leaching method. A porous scaffold consisting of PLGA and SIS as carrier
of BDNF has been prepared in the presence of ice particle. SEM image of the PLGA/SIS scaffold
showed an interconnected pore structure. The release behavior of BDNF loaded PLGA/SIS scaffold
was examined for 4 weeks period at phosphate buffered saline (PBS, pH 7.4) at 37 oC. The
sustained release of BDNF over 4 weeks was observed from the PLGA/SIS scaffold. These results
indicate that the sustained release of BDNF from PLGA/SIS scaffold can be very useful for
application in the tissue engineering.
Aqueous Solubilization of Paclitaxel Using Hydrotropic Polymer Micelle
Authors: Min Hyun Su , Lee Hong Jae , Lee Sang Cheon , Kang Kyoung Hoon , Lee Jae Hwi , Park Ki Nam , Huh Kang Moo
Published: March 2009

Hydrotropic block copolymers, consisting of a hydrophilic poly(ethylene glycol) (PEG)
block and a hydrotropic polymer, poly(2-(4-(vinyl benzyloxy)-N,N-diethylnicotinamide))
[P(VBODENA)], block, were synthesized by atom transfer radical polymerization (ATRP) for
aqueous solubilization of paclitaxel, a representative poorly water-soluble drug. These polymers
showed an excellent solubilizing effect for paclitaxel in aqueous media in comparison with the
corresponding hydrotropic agent and a control micelle (PEG-PLA) and such effect was significantly
dependent on the polymer concentration and composition. Paclitaxel could be solubilized into
polymer micelles in aqueous media without use of an organic solvent. Due to their promising
properties such as micellar characteristics and hydrotropic solubilization, the hydrotropic polymer
micelle system can be useful for formulation of paclitaxel and other poorly soluble drugs.
Release of All-Trans Retinoic Acid (RA) from RA-Loaded Poly(Ester Amine) Based on Polyethylenimine and Polycaprolactone for Intracellular Delivery
Authors: Guo Ding Ding , Arote Rohidas B. , Jiang Hu Lin , Yoo Mi Kyong , Moon Hyun Seuk , Cho Chong Su
Published: March 2009

The objective of this study is to develop a new type of cationic nanoparticles for the
intracellular drug delivery to breast cancer. Poly(ester amine) (PEA) based on polyethylenimine and
polycaprolactone was synthesized to make cationic PEA nanoparticles for all-trans retinoic acid
(RA). In the 1H-NMR study, the proton signals of RA appeared in the spectrum of RA-loaded PEA
nanoparticles in CDCL3, whereas they disappeared in D2O, suggesting that hydrophobic inner-core
with hydrophilic outer-shell formed in water. RA release was faster at lower drug content and RA
was released over a period of 20 days. RA-loaded PEA nanoparticles showed enhanced cytotoxicity
compared with RA itself, whereas nanoparticles of PEA themselves did not show it. These results
indicated that the cationic PEA provided an efficient intracellular delivery of RA.
Galactosylated Chitosan/Carbonate Apatite Nanohybridization for Cell Specificity and High Transfection Efficiency as a DNA Carrier
Authors: Park In Young , Kim Tae Hee , Kim You Kyoung , Choi Yun Jaie , Nah Jae Woon , Cho Chong Su
Published: March 2009

The strategies developed for gene delivery are generally classified into two categories of
viral and non-viral vectors. The limitation of viral vectors, which have problems including toxicity,
immunogenicity and inflammatory response has led to the development of a novel, synthetic vectors
based on non-viral vectors. Chitosan, one of non-viral vectors, has been a good candidate in gene
delivery field. Moreover, galactosylated chitosan (GC) had the specific recognition of hepatocytes
by galactose in the GC. Also, carbonate apatite increased the rate of DNA endocytosis and the
efficiency of gene transfer. We describe here a new concept for improving cell specificity and
transfection efficiency by hybridization of carbonate apatite (CAp) with GC. The complex
formation was confirmed by agarose gel electrophoresis. The complex optimized through
controlling calcium ion and charge ratio was evaluated on the cell specificity and transfection
efficiency.
Thiolated Eudragit-Coated Chitosan Microspheres as an Oral Drug Delivery System
Authors: Quan Ji Shan , Jiang Hu Lin , Choi Yun Jaie , Yoo Mi Kyong , Cho Chong Su
Published: March 2009

The aim of this study is to prepare mucoadhesive chitosan microspheres for protein drug
to deliver to intestine through oral administration. The thiolated Eudragit was synthesized by
reaction between L-cysteine hydrochloride and Eudragit® L-100. About 8 mol-% of cysteine was
introduced to the Eudragit-cysteine conjugate. The conjugate was used to coat bovine serum
albumin (BSA)-loaded chitosan microspheres. The average particle sizes of BSA-loaded thiolated
Eudragit-coated chitsoan microspheres (TECMs) were 4.06±0.74 .m and the uniform sizedistribution
was shown. The in vitro release of BSA from BSA-loaded TECMs was pH-dependent.
Our results indicated that thiolated Eudragit might be a good candidate as a coating material for oral
delivery of protein drug owing to mucoadhesive and pH-sensitive properties.
Receptor-Mediated Gene Delivery Using Chitosan Derivatives In Vitro and In Vivo
Authors: Kim Tae Hee , Jin Hua , Kim Hyun Woo , Cho Myung Haing , Nah Jae Woon , Cho Chong Su
Published: March 2009

The key strategy for the advancement of gene therapy is the development of an efficient
targeted gene delivery system into cells. The targeted gene delivery system is especially important in
non-viral gene transfer which shows the relatively low transfection efficiency. It also opens the
possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been
considered to be a good candidate for gene delivery system, since it is already known as a
biocompatible, biodegradable, and low toxic material with high cationic potential. However, low
specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In
this study, we focused on the chemical modification of chitosan for enhancement of cell specificity
and transfection efficiency. Also, the potential of clinical application was investigated.
Preparation of Naphthalocyanine Dendrimer Loaded Polyion Complex Micelle for Photodynamic Therapy
Authors: Jang Woo Dong , Nishiyama Nobuhiro , Kataoka Kazunori
Published: March 2009

A naphthalocyanine dendrimer (DNPcZn) was synthesized as a potential
candidate of photosensitizer for photodynamic therapy. DNPcZn exhibited strong Q
band absorption around 780 nm, a useful wavelength for high tissue penetration. A
polyion complex (PIC) micelle (DNPcZn/m) system was formed via an electrostatic
interaction of anionic DNPcZn and poly(ethylene glycol)-poly(L-lysine) block
copolymers (PEG-b-PLL).
The Bone Remodeling and Cellular Responses to Cranial Suture Distraction Osteogenesis in Growing Goats
Authors: Zhang Qi Feng , Zou Shu Juan , Zhou Hai Xiao , Chen Yang Xi , Qi Meng Chun , Zhao Zhi He
Published: March 2009

The purpose of the present study was to observe the response and changes of cranial
suture to the distraction forces in growing goats and to examine the expression patterns of TGF-β
and BMP during suture distraction.Twenty growing goats were divided into three groups: control
(n=4), experimental (n=12), and sham (n=4). A pure titanium distractor was placed in the coronal
suture in both the sham and experimental groups. After healing, the distractor was activated for
distraction of the coronal suture at a rate of 0.5 mm/day for 8 days in the experimental group. Three
animals were killed respectively, at 0，2，4 and 8 weeks after completion of suture distraction. No
force was applied in the sham group. X- Ray examination was taken and the coronal suture samples
were harvested and processed for histological analysis and scanning electron microscopic analysis
and immunohistochemistry of TGF-β and BMP. The coronal sutures of experimental group were
separated successfully. Signs of intramembranous bone formation and remodeling were found in the
distracted suture，and the sutural structure almost return to its normal state at 8 weeks after end of
distraction. At 0 and 2 weeks after completion of suture distraction, the collagen fiber bundles were
strengthened and aligned in the direction of the distracted forces. Strong expression of BMP and
TGF-β were detected in the fibroblast-like cells and the active osteoblasts. At 4 weeks after suture
distraction, signs of intramembranous ossification were found in the edge areas of the distracted
suture, and the positive staining of BMP and TGF-β was still noted in the osteoblasts around the
newly formed bone trabeculae. This study suggests that cranial suture expansion can be achieved in
growing animal by distraction osteogenesis. Mechanical strain resulted from distractor can induce
the adaptive remodeling in the cranial suture of growing goats. It also suggests BMP and TGF-β
may play very important roles in the process of bone formation and remodeling during suture
distraction osteogenesis.
Controlled Angiogenic Factor Release from Alginate Gels
Authors: Lee Kuen Yong , Nishishita Naoki , Hirano Yoshiaki , Mooney David
Published: March 2009

Therapeutic angiogenesis by localized delivery of angiogenic factors is a promising
approach to treat patients with cardiovascular disease and to engineer large tissues. Vascular
endothelial growth factor (VEGF) is the most common and biologically active form of the VEGF
family, which acts as a mitogen to endothelial cells and is capable of specific binding to heparin.
However, when VEGF is administered via bolus injection, it can be widely distributed, and its
concentration is likely to be within the effective window for only a short time period due to rapid
degradation. Delivery of angiogenic factors, using controlled drug delivery strategies, offers great
potential to promote angiogenesis at a specific site while reducing the unwanted side effects that
may occur with systemic delivery. We now report on the sustained release of VEGF from alginate
gels, modified with a heparin-binding peptide. Briefly, a small peptide with the sequence of
G5K(βA)FAKLAARLYRKA, which is known to specifically interact with heparin, was chemically
conjugated to alginate, and the peptide-modified alginate formed gels after mixing with heparin and
VEGF. The release rate of VEGF from the gels slowed in vitro for over 45 days, compared with
release from non-modified alginate gels. This result suggests potential applications of alginate gels
in promoting angiogenesis for therapeutic purposes, as well as for tissue engineering.
A Study on the Interface between Oxide Film on the Titanium Surface and Bone Tissue
Authors: Wang Li Ping , Yang Bang Cheng , Chen Ji Yong , Zhang Xing Dong
Published: March 2009

The bioactivities of titanium oxide film on titanium surface received from different
chemical treatment methods were studied in SBF in vitro and mechanically and histologically
investigated in vivo. Three groups of titanium specimens were prepared: untreated titanium(S),
acid-alkali treated titanium (H), and acid-alkali and heat-treated titanium(X). The oxide film of X
surface resulted in more apatite formation and significantly higher strength of the interface between
the samples and bone than those of the other titanium groups. The surface of the acid-alkali treated
titanium and that further treated by heat treatment had higher bioactivity and stronger bone-bonding
ability.
Current Density Contour Map of TiNi Shape Memory Alloy in Simulated Physiological Solutions
Authors: Hwang Woon Suk , Na Seung Chan , Lee Jeong Ja
Published: March 2009

In order to investigate the corrosion behavior of TiNi shape memory alloy, especially
electrochemical behavior of pitting and crevice corrosion in a human body, current density
contour(CDC) map of TiNi alloy was constructed by potentiodynamic polarization technique in
simulated physiological sodium chloride solutions of pH ranging from 1 to 13 at 37oC. Morphology
of pits and corrosion products in sodium chloride solutions of various pH were analyzed by SEM
and EDX, and susceptibility and mechanism of localized corrosion were also discussed.
In Vitro Biocompatibility of a New High Nitrogen Nickel Free Austenitic Stainless Steel
Authors: Ren Yi Bin , Yang Hua Juan , Yang Ke , Zhang Bing Chun
Published: March 2009

The in vitro blood compatibility of a new nickel free high nitrogen austenitic stainless
steel Fe-Cr-Mn-Mo-N (BIOSSN4) was studied by the kinetic clotting time test and the platelet rich
plasma adhesion test in this paper. In comparison with 316L stainless steel, the kinetic clotting time
of BIOSSN4 steel are longer, and only causes less activation of platelets in platelet adhesion test,
which was indicated by their morphology and low spreading. The experimental results reveals that
the BIOSSN4 stainless steel has better blood compatibility, the blood compatibility mechanism of
steels was analyzed based on surface tension and interfacial tension between the steels and blood.
Thinfilm Deposition and Characteristics of Calcium-Silicates Bioglass
Authors: Han In Ho , Lee In Seop , Choi Jai Hyuk , Baik Hong Koo
Published: March 2009

Various composition of calcium-silicate thinfilms were deposited to the thickness of 1μm by
electron-beam deposition. The composition was varied by changing the composition of source.
The Si concentration of thinfilm was ranged from 25 at% to 85 at%, evaluated by EDS. The
specimens were immersed into PBS solution at 37 °C. Changes of the morphology and calcium
phosphate formation on the specimens were examined by SEM. If the concentration of calcium is
high, the calcium phosphate was quickly formed on the specimen. However, the calcium
phosphate formed on the high calcium oxide concentration exhibited very poor adhesion onto the
substrate. There is a range of appropriate calcium oxide concentration to use as a surface
modification method for dental or orthopedic implants.
The Multi-Channels Measurement of Strain Generated Potentials in Osseointegrated Implant-Bone Composite
Authors: Hong Jung Hwa , Ko Sang Ok
Published: March 2009

Osseointegration (OI) could be described as the modality for stable fixation of titanium
implant to bone structure. The OI has become a realized phenomenon of importance in the dental
and rehabilitation sciences since recently developed dentures and artificial limbs are directly
attached to human skeleton by using osseointegrated implants. Previously, a study showed that bone
strain generated potential (SGP) that is an electrical potential and considered to be generated by
fluid flow in bone could be used as a parameter to examine the amount of OI on implant-bone
interface. Since no study was performed to understand SGP behavior as a function of position for
the implant-bone composite, a one-dimensional map of SGP was constructed along the longitudinal
direction of the composite. For the purpose, nine electrodes including one reference were
instrumented on the wet composite for the one-dimensional mapping of SGP during compression
tests. The peak magnitudes of SGP were found to be significantly increased when the measurement
position was approached for the interface of implant-bone. The results could indicate that the spatial
SGP behavior of osseointegrated implant-bone composite could be caused by the interface of the
implant-bone.
Mechanism Study of Calcium Phosphate Deposition on Titanium Surface in Simulated Body Fluid
Authors: Zhao Zhan Feng , Lu Xiong , Leng Yang
Published: March 2009

Previously, various surface treatments have been used to enhance the ability of titanium
surfaces to induce calcium phosphate (Ca-P) formation in simulated body fluid (SBF). However,
there were no systematic investigations on the key factors of the surface treatments to control such
ability. In this work, three factors are studied for their roles in controlling Ca-P precipitation in
SBF: surface roughness, surface chemistry and surface energy. Four kinds of single-step chemical
treatments on Ti surfaces were carried out, including alkali treatment (AT), nitric acid treatment
(NT), hydrogen peroxide treatment (HPT), and heat treatment. The experimental results show that
the surface energy is the most likely controlling factor of Ca-P formation ability.
The Effect of Microarc Oxidation Ceramic Coating on Sensory Reconstruction around Implants Using Cultured Schwann Cells
Authors: Yuan Quan , Tan Zhen , Gong Ping , Nie Rong Rong , Li Xiao Yu , Shen Li Ru , Ban Yu , Tang Hua , Wang Fang Fang , Man Yi , Wei Na , Zhu Z.L.
Published: March 2009

Osseointegrated titanium implants have been widely used in clinics for replacement of missing teeth. However, sensory perception thresholds of implants were 10 to 100 times higher than those of natural teeth. The purpose of this study was to evaluate the effect of the ceramic coating generated by microarc oxidation (MAO) on sensory reconstruction around dental implants. The MAO coating was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and scanning probe microscope (SPM). Moreover, the chemical composition was analyzed with an energy dispersive spectroscope (EDS). Using smooth titanium discs as a control, Schwann cell responses to the coating were evaluated by SEM, MTT assay, total protein content and leakage of cytosolic lactate dehydrogenase (LDH) activity. In addition, the amount of brain-derived neurotrophic factor (BDNF) secreted by Schwann cells was measured by Enzyme-Linked Immunosorbent Assay (ELISA). It was observed that the porous coating had separated and homogeneous micropores in the diameter of 1-2 μm. The concentrations of Ca and P in the layer were 8.63% and 5.23% respectively. The cell morphology, proliferation and secretion of BDNF were unaffected. The results indicated that the MAO ceramic coating developed on the surface of pure titanium had good biocompatibility with Schwann cells for sensory reconstruction around dental implants.
Hydrogel Composed of Chitosan and Cyclodextrin and Evaluation of its Antioxidant Activity
Authors: Jung Byung Ok , Lee Sang Bong , Na Jae Sik
Published: March 2009

The hydrogels composed of chitosan and carboxylmethyl-β-cyclodextrin (CMCD) were
prepared to enhance and sustain the antioxidant activities. The carboxylic groups of CMCD were
directly grafted and cross-linked on the amino groups of chitosan. The swelling rate decreased with
increasing the CMCD contents in the hydrogel and the swelling ratio of CMCD-grafted chitosan
hydrogels was improved due to breaking the crystallinity of chitosan caused by introducing the
bulky group such as cyclodextrin. The scavenging activity of the tested hydrogels increased with
CMCD contents, because antioxidants entrapped in the CMCD were potent free radical terminators.
Synthesis and Biological Activities of Sulfonated Polysaccharides Having Pentofuransidic Structures
Authors: Kang Byung Won , Yoshida T. , Lee Jong Baek , Jeon S.J. , Choi H.D.
Published: March 2009

In order to elucidate the relationship between the structure and biological activity such as
anti-HIV and blood anticoagulant activity, sulfonated polysaccharides and amino-polysaccharides
having pentofuranosidic structures were synthesized. These sulfonated polysaccharides had potent
anti-HIV activity in spite of low molecular weights, and which was dependent on the degree of
sulfonation. For the blood anticoagulant activity, the conformation of polymer backbone and
sulfamide group plays an important role on the interactions with the blood anticoagulant factor.
Preparation and Characterization of Poly(ε-Caprolactone)/Multiwalled Carbon Nanotube Composites
Authors: Kim Hun Sik , Park Byung Hyun , Chae Yun Seok , Yoon Jin San , Jin Hyoung Joon
Published: March 2009

In this study, poly(ε-caprolactone) (PCL)/multiwalled carbon nanotube (MWCNT)
composites with different contents of MWCNTs were successfully prepared by solution
compounding, a method which could make them good competitors for commodity materials such as
general purpose plastics, while allowing them to keep their complete biodegradability. For the
homogeneous dispersion of the MWCNTs in the polymer matrix, oxygen-containing groups were
introduced on their surface. The mechanical properties of the PCL/MWCNT composites were
effectively increased due to the incorporation of the MWCNTs. The composites were characterized
using scanning electron microscopy, in order to obtain information on the dispersion of the MWCNTs
in the polymeric matrix. In the case of the composites containing 2.0 wt% of MWCNTs in their
matrix, the strength and modulus of the composites were increased by 18.4% and 178.4%,
respectively. In addition, the dispersion of the MWCNTs in the PCL matrix resulted in a substantial
decrease in the electrical resistivity of the composites as the MWCNT loading was increased from 0 to
2.0 wt%.
Characterization of Hyaluronic Acid-Poly(Ethylene Oxide) Hydrogel Dependent upon Poly(Ethylene Oxide)
Authors: Kim Mi Sook , Choi Yoon Jeong , Kim Gun Woo , Noh In Sup , Park Yong Doo , Lee Kyu Back , Kim In Sook , Hwang Soon Jung , Yoon Gil Won
Published: March 2009

Characterization of an hyaluronic acid (HA)-poly(ethylene oxide) (PEO) hydrogel was
performed by changing the number of side arms in a PEO molecule. Verification of grafting
chemistry and mechanical strength, as well as swelling behaviors and surface morphologies of the
HA-PEO hydrogels were analyzed by employing different x-linking molecular weights (MW) of
PEO ranging from 1.7 to 5.0 kDa at a fixed low MW HA in the hydrogel network. Methacrylation
to the HA successfully obtained via Michael type reaction between the methacrylate arm groups in
HA and the thiol end groups in PEO was observed by XPS. Hydrogel formation was markedly
dependent upon the numbers of thiol groups in the PEO molecule. Furthermore the lower MW
PEO-based HA hydrogel demonstrated stronger mechanical properties but lower water absorption
and the smaller pore sizes on its surface and cross section.
Preparation and Characterization of Bone Cements Incorporated with Montmorillonite
Authors: Lee Sun Yeon , Kim Sung Soo
Published: March 2009

Bone cements incorporated with montmorillonite (MMT) were prepared in an attempt to
improve their mechanical properties. The cements were characterized using particle size analysis,
gel permeation chromatography, viscosity measurements, X-ray diffraction, transmission electron
microscopy, and mechanical properties. The average particle size and molecular weight of the
PMMA powders used were 47 μm and 100,000 g/mol, respectively. The incorporation of MMT led
to an increase in viscosity of the bone cement but did not severely affect its setting temperature or
the amount of residual monomer. Regardless of the MMT mixing methods used, in this case MMT
being mixing in liquid and powder components, sodium MMT (SMMT) was not well dispersed in
the bone cements, which was believed to be due to its hydrophilicity. Organophilic MMT (OMMT)
was better dispersed in the liquid component than in the powder component. The tensile and
compressive strengths of the bone cements with 0.5 wt% OMMT mixed in the liquid component
were 35.9 and 119.6 MPa, respectively, which were considerably higher than those of the bone
cements with 0.5 wt% OMMT mixed in the powder component (27.9 and 100.5 MPa, respectively).
Biodegradable Porous PCL/HA Scaffolds for Bone Tissue Engineering
Authors: Kim Seung Eon , Hyun Yong Taek , Chung Dong June , Heo S.J. , Shin Jung Woog , Lee J.H.
Published: March 2009

Poly ε-caprolactone(PCL)/hydroxyapatite(HA) composite scaffolds were fabricated by
particulate leaching and freeze drying routes with different HA content. Porosity was decreased
with HA addition, while mean pore size was maintained at around porogen size regardless of HA
content. Compressive modulus was increased with increasing HA content. In this study, the
optimum content of HA was around 40% in weight against PCL to obtain the highest compressive
modulus with keeping porosity above 85%. HA apparently enhanced proliferation of osteoblast-like
MG63 cells in PCL/HA composite scaffolds. Typical adhesion, migration and aggregation
procedure of MG63 cells were found on PCL, while spreading morphology only was found on HA
even at the early stage of adhesion without migration or aggregation.