bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation of a Sensing Membrane for C‐Reactive Protein
Authors: Kim Huyn‐Chul , Lee Soo‐Keun , Sohn Young‐Soo , Ryu Hong‐Kun , Jeong Sang Won 
Published: March 2007

Abstract11,11′‐dithiobis(undecanyl succinate) (DS11SACOOH) was synthesized to develop a new surface for immobilization of proteins or antibodies on a gold substrate. DS11SACOOH is a bifunctional linker that has a disulfide group to form SAM (self‐assembled monolayer) on a gold substrate and two carboxylic moieties for reaction with biomolecules such as peptide, DNA, etc. After preparation of SAM on a gold‐coated quartz cell with DS11SACOOH, the SAM surface was activated with NHS (N‐hydroxysuccimide). The terminal NHS ester was reacted with anti‐CRP (C‐reactive protein). The binding behavior of CRP on the surface was monitored by use of SPR (surface plasmon resonance) sensor system.
Preparation and Characterization of Bone Cements Incorporated with Montmorillonite
Authors: Kwon Soon Yong , Kim Sung Soo 
Published: March 2007

AbstractBone 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, unreacted monomer analysis, X‐ray diffraction, transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, 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 compressive and tensile strength of the bone cement containing the OMMT mixed into the liquid component were significantly higher than those of the bone cement without MMT (p < 0.05).
Surface Characteristics of Plasma‐Treated PLGA Nanofibers
Authors: Park Ko Eun , Lee Kuen Yong , Lee Seung Jin , Park Won Ho 
Published: March 2007

AbstractPLGA nanofibers were prepared by an electrospinning method (mean diameter, 340 nm) and treated with plasma in the presence of either oxygen or ammonia gas to modify the surface of the nanofibers. The surface hydrophilicity of electrospun PLGA nanofibers was greatly increased by plasma treatment, which was confirmed by contact angle measurement. XPS analysis demonstrates that the number of polar groups on the surface of PLGA nanofibers after plasma treatment was increased, and this was considered to contribute to the enhanced surface hydrophilicity of the nanofibers. This approach to controlling the surface properties and structures of nanofibers could be useful in the design and tailoring of novel synthetic extracellular matrices for tissue engineering applications.
Anticancer Drug‐Phospholipid Conjugate for Enhancement of Intracellular Drug Delivery
Authors: Hwang Taewon , Han Hee Dong , Song Chung Kil , Seong Hasoo , Kim Jung Hyun , Chen Xiaoyuan , Shin Byung Cheol 
Published: March 2007

AbstractTumor specific delivery of anti‐cancer drugs is one of the major challenges faced by drug development processes. In this study, we prepared a doxorubicin (DOX)‐conjugated liposome (DCL) by incorporating the newly synthesized DSPE‐PEG2000‐DOX (DPD) into liposomes as a lipid component and tested its anti‐tumor activity in vivo. DPD was synthesized by coupling DOX to DSPE‐PEG2000‐COOH via amide linkage and the chemical structure of resulting DPD was confirmed by 1H‐NMR analysis. DCL having liposome size of 130 nm was prepared through thin film cast‐hydration method. DCL was found to have significantly higher cellular uptake than conventional liposomes as confirmed by flow cytometry analysis. Anti‐tumor activity of DCL against murine B16F10 melanoma tumor‐bearing mice revealed that DCL inhibits tumor growth more efficiently than the conventional liposomes, presumably attributed to DOX mediated endocytosis process.
New Sol‐Gel Transition Hydrogels Based on Pluronic‐Mimicking Copolymers Grafted with Oligo(lactic acids)
Authors: Lee Yuhan , Park Sung Young , Chung Hyun Jung , Park Tae Gwan 
Published: March 2007

AbstractA novel type of poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide) (PEO‐PPO‐PEO) triblock copolymers grafted with oligo(D,L‐lactic acid) (OLA) on the middle PPO segment was synthesized. The Pluronic‐mimicking copolymers exhibited gel‐to‐sol transitions with increasing temperature over a wide range of copolymer concentrations, and formed more stable hydrogel structures than Pluronic F127 copolymer in aqueous solution. The gel‐to‐sol phase transition temperature was controllable depending on chain length of the grafted OLA on the PPO chain. The gel‐to‐sol transition occurring with raising temperature was attributed to thermal destabilization and expansion of the inner hydrophobic core, which disturbed the packing order of spherical micelles required for physical gelation. The OLA grafted Pluronic mimicking hydrogels not only showed highly retarded erosion at 37 °C but also sustained protein release profiles, compared to Pluronic F127 hydrogel.
Receptor‐Mediated Gene Delivery Using Chitosan Derivatives in Vitro and in Vivo
Authors: Kim Tae‐Hee , Jiang Hu‐Lin , Nah Jae‐Woon , Cho Myung‐Haing , Akaike Toshihiro , Cho Chong‐Su 
Published: March 2007

AbstractThe development of an efficient targeted gene delivery system into cells is an important strategy for the advancement of gene therapy. The targeted gene delivery system is especially important in non‐viral gene transfer which shows the relative low transfection efficiency. And it also opens the possibility of selective delivery of therapeutic plasmids to specific tissues. Chitosan has been investigated as a non‐viral vector because it has several advantages such as biocompatibility, biodegradability and low toxicity with high cationic potential. However, low specificity and low transfection efficiency of chitosan need to be overcome prior to clinical trial. In this review, we focused on the specific ligand modification of chitosan for enhancement of cell specificity and transfection efficiency via receptor‐mediated endocytosis in vitro and in vivo.
Preparation of Biodegradable Polymer Scaffolds with Dual Pore System for Tissue Regeneration
Authors: Park Kwideok , Jung Hyun Jung , Son Jun Sik , Park Ki Dong , Kim Jae‐Jin , Ahn Kwang‐Duk , Han Dong Keun 
Published: March 2007

AbstractBiodegradable polymer scaffolds that have dual pores on the matrix were successfully prepared using a combination of gas foaming and phase separation methods. PLLA and PLGA were dissolved in dioxane/water at the ratios of 90/10, 87/13, or 85/15 (v/v), respectively. Sodium bicarbonate was then added to the polymer solution and freezed‐dried, then subjected to a gas foaming process. Dual pore scaffolds have two distinct pore sizes: large pores in 200∼300 µm and small ones in 5∼20 µm, with the interconnected structure. Their porosities were ranged from 92 to 98%, significantly higher than those of unipore scaffold (90%). Two variables, water content (10, 13, and 15%) and freeze‐drying temperature (FDT; −196, −70, and −20 °C), were introduced during the scaffold preparation. Mechanical compressive strength decreased as the polymer solution was gradually diluted with water (100/0 to 85/15, v/v). Earlier weight loss of the different scaffolds was found with FDT at −20 °C but the final result was the same, regardless of different FDTs used. These dual pore polymer scaffolds may thus be useful in tissue engineering applications.
Dye Sensitized Solar Cell Using Polymer Electrolytes Based on Poly(ethylene oxide) with an Ionic Liquid
Authors: Singh Pramod K. , Kim Ki‐Il , Park Nam‐Gyu , Rhee Hee‐Woo 
Published: March 2007

AbstractPolymer electrolytes were prepared by doping PEO:KI/I2 with an ionic liquid (IL) 1‐ethyl 3‐methylimidazolium thiocyanate (EMImSCN). FTIR confirmed composite nature while X‐ray diffraction (XRD) measurement affirmed the reduction in crystallinity, when IL was added. The ionic conductivity was improved by the addition of IL. The photoelectrochemical effect of the IL–doping in the terms of the current density Jsc and efficiency of a dye sensitized solar cells (DSSC) has also been discussed.
Development of Solid‐State Alkaline Electrolytes for Solid Alkaline Fuel Cells
Authors: Park Jin‐Soo , Park Gu‐Gon , Park Seok‐Hee , Yoon Young‐Gi , Kim Chang Soo , Lee Won Yong 
Published: March 2007

AbstractSolid‐state alkaline electrolytes were prepared from chloromethylated polysuflone (CMPSf) and a number of mono‐ and diamine compounds for solid alkaline fuel cell (SAFC) applications. Chloromethyl‐groups as substituents for aromatic nuclei were introduced to an aromatic polymer in the presence of a Friedel‐Crafts catalyst and then the basic groups into polymer by amination using N‐trimethylamine (TMA) and N,N,N′,N′‐tetraemethylhexanediamine (TMHDA). The properties of the solid‐state alkaline electrolytes were invetigated in terms of OH– conductivity, water content and thermal stability.
PMMA Encapsulated Silica Particles by Dispersion Polymerization in Supercritical Carbon Dioxide
Authors: Park Eun Ju , Kim Won Soo , Hwang Ha Soo , Park Chan , Lim Kwon Taek 
Published: March 2007

AbstractPMMA encapsulated silica particles were synthesized by the dispersion polymerization of MMA in supercritical carbon dioxide (scCO2). Nanosized silica particles pretreated with 3‐(trimethoxysilyl) propyl methacrylate (γ‐MPS) were used as seeds in the polymerization. Polymeric stabilizer, poly(dimethylsiloxane)‐b‐poly (methacrylic acid) (PDMS‐b‐PMA) copolymer provided sufficient stabilization to the silica/PMMA composite latexes in scCO2 to produce spherical particles. SEM and TEM analysis revealed that the composite particles have core‐shell type morphology.
In‐situ Crosslinked Polymer Electrolyte Membranes from Thermally Reactive Oligomers for Direct Methanol Fuel Cells
Authors: Park Sam Dae , Chang Yoon Ju , Jung Jin Chul , Lee Wonmok , Chang H. , Kim Haekyoung 
Published: March 2007

AbstractThermally reactive ally‐terminated sulfonated oligosulfone was easily synthesized and made it possible to fabricate crosslinked membrane with high ionic group contents for direct methanol fuel cells. The crosslinked network structures of rigid rod sulfonated polyarylene sulfone showed high suppression of swelling with high sulfonation degree of 70%, which gave excellent properties for direct methanol fuel cell applications. The proposed membranes gave unprecedented reduction in methanol cross‐over (less than 3% of Nafion 112) and high ionic conductivity (∼80% of Nafion 112).
Conductivity Behaviour of Nanocomposite Polymer Electrolytes: Role of Fumed Silica and Plasticizer
Authors: Sekhon S. S. , Sharma J. P. , Park J. S. 
Published: March 2007

AbstractPolymer electrolytes obtained by the complexation of ammonium bifluoride (NH4HF2) with polyethylene oxide (PEO) have been studied. The addition of propylene carbonate (PC) results in conductivity enhancement by two orders of magnitude and shows conductivity of 1.4 × 10−4 S/cm at 25 °C, whereas the addition of fumed silica results in conductivity enhancement and show conductivity of 1.19 × 10−5 S/cm at 25 °C. However simultaneous addition of plasticizer (PC) and fumed silica to polymer electrolytes has been found to result in higher conductivity of 1.55 × 10−4 S/cm at 25 °C alongwith better mechanical properties. The complexation of NH4HF2 with PEO, formation of ion aggregates and their dissociation with the addition of PC has also been studied by FTIR.
Preparation of Buckyball‐Shaped Conducting Polythiophene by the Gamma Radiation‐Induced Polymerization Method
Authors: Karim Mohammad Rezaul , Lee Chul Jae , Kim Hee Jin , Bhuiyan Md Tauhidul Islam , Lee Mu Sang 
Published: March 2007

AbstractWe report on a fascinating morphology; giant spherical conducting polythiophene by the in‐situ gamma radiation‐induced chemical polymerization method. The resultant micron‐size buckyball‐shaped polymer structures were identified by high resolution transmission electron microscopy and scanning electron microscopy. Different characterizations e.g. elemental analysis, Fourier transform infrared, x‐ray diffraction, and x‐ray photoelectron spectroscopy were utilized to prove that the new morphological conducting polythiophene was synthesized successfully by this novel method.
High‐K and Low Loss Bi1.5Zn1.0Nb1.5O7/Polyimide Composite Films for Application in Embedded Capacitors
Authors: Choi Seung‐Hoon , Kim Il‐Doo , Hong Jae‐Min , Oh Seong‐Guen 
Published: March 2007

AbstractWe report on the role of Bi1.5Zn1.0Nb1.5O7 (BZN) ceramic fillers in notably reducing the dielectric loss of BZN/polyimide composite films manufactured for application in flexible RF embedded capacitors. The composite films were synthesized using a colloidal process. INAAT (isopropyl tris(N‐amino‐ethyl aminoethyl)titanate) was used as a coupling agent for homogeneous dispersion of BZN particles into a polyimide matrix. The BZN/polyimide composite films (BZN content at 50 Vol%) exhibited a low dielectric loss of 0.0369 at 12 MHz while retaining a high dielectric constant of 14.75.
Synthesis and Characterization of Waterborne Polyurethane/Clay Nanocomposite – Effect on Adhesive Strength
Authors: Rahman Mohammad Mizanur , Yoo Hye‐Jin , Mi Chung Jung , Kim Han‐Do 
Published: March 2007

AbstractWaterborne polyurethane (WBPU)/clay nanocomposites were synthesized using prepolymer process with different clay content (0–5 wt%) of organoclay cloisite 15A. The optimum dispersion temperature of clay in polyol was found to be 80 °C at 3 hours. The XRD confirmed the exfoliation dispersion of clay by polyol in WBPU/clay nanocomposite. IR and 1H‐NMR spectroscopy confirmed the unreacted condition of clay component. Particle size of the WBPU/clay nanocomposite dispersion was increased with increasing of clay concentration. Water swelling was decreased with increasing of clay up to the optimum content (2 wt %) and then leveled off. The thermal stability, mechanical property and adhesive strength were increased with increasing clay content up to 2 wt% to reach its maximum value.
Multiwalled Carbon Nanotube‐Reinforced Poly(vinyl chloride)
Authors: Jung Rira , Kim Hun‐Sik , Jin Hyoung‐Joon 
Published: March 2007

AbstractMultiwalled carbon nanotube (MWCNT)‐reinforced poly(vinyl chloride) (PVC) was prepared via a simple adsorption method in an aqueous system. MWCNTs possessing negatively charged carboxyl groups at their tips and sidewalls introduced during the purification process were dispersed in water with the cationic surfactant, cetyltrimethylammonium bromide, using ultra‐sonication. Then, PVC microspheres, which have a negative charge in water at pH 7.0, were added to the aqueous MWCNTs dispersion. As a result, the MWCNTs were stably and strongly adsorbed on the surface of the PVC microspheres by electrostatic interaction. Furthermore, the dispersivity of the MWCNTs in the PVC remained high, even when we manufactured the MWCNT‐adsorbed PVC microspheres in the form of solution cast films. The PVC/MWCNTs nanocomposite exhibited a marked increase in its electrical conductivity, in spite of the relatively low MWCNT content (2.9 wt%). The composite films also showed an improvement in their mechanical properties, such as their tensile strength and Young's modulus.
Luminescent Polymer Latex Particles Prepared by Oxidative Polymerization in Emulsion Polymerization
Authors: Jung Yeon Jae , Lee Jung Min , Cheong In Woo , Kim Jung Hyun 
Published: March 2007

AbstractIt was demonstrated that core‐shell poly(styrene/thiophene) latex particles were successfully prepared by oxidative polymerization during emulsifier‐free emulsion polymerization. This method provided a new fabrication route of core‐shell type luminescent polymer particles with a thin shell layer. The core/shell structure of the resulting latex particles was proved by SEM analysis. It supported a strong evidence that each composition was isolated in independent domains, and which was corroborated by the TGA analysis. The resulting latex particles showed that luminescence efficiency in the solid state was better than that in the emulsion state due to the core‐shell morphology with a thin shell structure. This new strategy is universal for the synthesis of many other materials or composite particles with controlled morphology. Such core‐shell morphology controlled conjugated polymer composite particles may have potential practical applications in various electrical and electro‐optical devices, especially in polymer light emitting diodes (PLEDs).
Study on the Functionalization of Multi‐Walled Carbon Nanotube with Monoamine Terminated Poly(ethylene oxide)
Authors: An Jung Sook , Nam Byeong‐Uk , Tan Soon Huat , Hong Sung Chul 
Published: March 2007

AbstractThrough the introduction of carboxylic acid or thionyl chloride groups in multi‐walled carbon nanotubes (MWNT‐COOH or MWNT‐COCl) and amine group in poly(ethylene oxide) (PEO‐NH2), complexation of MWNT with PEO was successfully performed, yielding MWNT/PEO complex having approximately 40 wt.% of PEO. The MWNT/PEO complexes exhibited excellent dispersibility in solvents including water, ethanol and DMF. From SEM observation, the increases in the diameter of the nanotubes were observed. The presence of PEO on the nanotube surface was also confirmed through EDX and FT‐IR. The effects of different functionality on MWNTs (COOH vs. COCl) and different molecular weight of PEOs (1000 g/mol vs. 2000 g/mol) were not so prominent.
Ultrasonic Effects on PP/PS/Clay Nanocomposites during Continuous Melt Compounding Process
Authors: Kim Kyung Yl , Ju Dong Uk , Nam Gi Joon , Lee Jae Wook 
Published: March 2007

AbstractPolymer blend/clay nanocomposites were prepared by ultrasonic‐assisted continuous extrusion process. This process was employed to enhance the compatibility between two polymers, and nano‐scale dispersion between the polymer blend and organically modified clay. Materials were linear polypropylene and polystyrene with 3 phr loading of organophilic montmorillonite clay. The effectiveness of the proposed ultrasonic‐assisted process on the polypropylene/polystyrene/clay nanocomposites was confirmed by rheological property measurements and structural analysis by scanning electron microscope and X‐ray diffraction. The sonication during extrusion was effective in improving the compatibility between polypropylene and polystyrene. Also, it led to enhanced breakup of the clay agglomerates. The observed clay was in the exfoliated state from the X‐ray diffraction analysis.
Electrospinning of Poly(ethylene oxide) with Bacterial Cellulose Whiskers
Authors: Park Won‐Il , Kang Minsung , Kim Hun‐Sik , Jin Hyoung‐Joon 
Published: March 2007

AbstractIn the present study, cellulose whiskers were incorporated into nanofibers of polyethylene oxide (PEO) by the electrospinning process to enhance the mechanical properties of the electrospun PEO fibers. Cellulose whiskers consisting of highly crystalline rod‐like particles with a high aspect ratio and specific area were obtained by the acid hydrolysis of bacterial cellulose microfibrils. From the transmission electron microscopy (TEM) images of the bacterial cellulose whiskers, their length was measured to be 420 ± 190 nm and their width 11 ± 4 nm. The height of the whiskers was measured to be 10 ± 2 nm by atomic force microscopy. The successful formation of electrospun fibers with a diameter of less than 1 µm and well‐embedded microfibrils was confirmed by scanning electron microscopy and TEM.
In‐situ Synthesis and Characterization of Polyamide 6/POSS Nanocomposites
Authors: Ramasundaram Subramaniya Pillai , Kim Kap Jin 
Published: March 2007

AbstractThe nanocomposites of polyamide 6 (PA6) and polyhedral oligomeric silsesquioxane (POSS) containing primary and secondary amino groups were synthesized through in‐situ polymerization. The chemical structure of the PA6/POSS nanocomposites was characterized with FT‐IR and 1H‐NMR spectroscopies. The solution viscosity results showed the increase in intrinsic viscosity with increasing POSS loadings. The random positioning of the POSS molecules in PA6 chain was confirmed by x‐ray diffraction studies. The gradual decrease in the melting point and crystallization temperature with increasing POSS content was observed by the differential scanning calorimetry. The thermogravimetric analysis results showed that the POSS incorporation does not enhance the thermal resistance of PA6/POSS nanocomposites.
The Synthesis of Random Brush for Nanostructure of Block Copolymer
Authors: Kim Bong Hoon , Koo Chong Min , Shin Dong Ok , Jeong Seong Jun , Kim Sang Ouk 
Published: March 2007

AbstractPolymer brush has been synthesized via conventional free radical polymerization to use a surface active material on the silicon substrate. The synthesized polymer brushes were successfully grafted onto the silicon oxide substrate and the hydrophilic silicon oxide substrate has been changed into the more hydrophobic one. The synthesized poly(styrene‐ran‐methyl methacrylate) brush grafted silicon substrate could provide poly(styrene‐block‐methyl methacrylate) with neutral surface.
Preparation of Cationic Comb‐Type Copolymers Having High Density of PEG Graft Chains for Gene Carriers
Authors: Choi Sung Won , Yamayoshi Asako , Hirai Miwa , Yamano Takeshi , Takagi Motoki , Sato Ayumi , Kano Arihiro , Shimamoto Akira , Maruyama Atsushi 
Published: March 2007

AbstractA series of poly(L‐lysine)‐graft‐polyethylene glycol (PLL‐g‐PEG) was prepared by a reductive amination reaction of PLL with aldehyde modified PEG using NaBH3CN as a reductant. The high coupling efficacy observed in the 80% acetonitrile aqueous solution led to the grafting polymers with abundant PEG chains (more than 90 wt % and 30 mol %). By the method, we can retain high cationic charge density of the polymer backbone, because the resulting secondary amino groups are still protonated. By controlling the primary structure of the copolymer, we can also regulate the ionic interaction with nucleic acids and other biological components for gene delivery purpose.
DNA Nanomachine Switching Improved by Cationic Comb‐Type Copolymer
Authors: Choi Sung Won , Makita Naoki , Kano Arihiro , Yamayoshi Asako , Akaike Toshihiro , Maruyama Atsushi 
Published: March 2007

AbstractThe unique folding and assembling properties of DNA have been elaborated to construct various nanomachines that can be reversibly switched between two or more distinct conformations. For the better applications and developments of DNA nanomachines, their responding kinetics, outputs, and sequence‐selectivity need to be improved. Furthermore, the DNA nanomachines currently have several limitations in the operation conditions such as temperature, salt condition, and DNA strand concentration. In this study, we evaluated the effect of a cationic copolymer on the responses of a DNA‐fueled nanomachine. We found that the copolymer increases quickness of the nanomachine under moderate conditions including physiologically relevant conditions even at very low strand concentrations (nM range).