bluuebunny/crossref_metadata_2025 huggingface dataset:
Raman Microscopy of Freeze‐dried Mouse Eyeball‐slice in Conjunction with the “in vivo Cryotechnique”
Authors: Terada Nobuo , Ohno Nobuhiko , Saitoh Sei , Fujii Yasuhisa , Ohguro Hiroshi , Ohno Shinichi
Published: March 2007

The wavelength of Raman‐scattered light depends on the molecular composition of the substance. This is the first attempt to acquire Raman spectra of a mouse eyeball removed from a living mouse, in which the eyeball was preserved using the “in vivo cryotechnique” followed by freeze‐drying. Eyeballs were cryofixed using a rapid freezing cryotechnique, and then sliced in the cryostat machine. The slices were sandwiched between glass slides, freeze‐dried, and analyzed with confocal Raman microscopy. Important areas including various eyeball tissue layers were selected using bright‐field microscopy, and then the Raman spectra were obtained at 240 locations. Four typical patterns of Raman spectra were electronically mapped on the specimen images obtained by the bright‐field microscopy. Tissue organization was confirmed by embedding the same eyeball slice used for Raman spectra into epoxy resin and the thick sections were prepared with the inverted capsule method. Each Raman spectral pattern represents a different histological layer in the eyeball which was mapped by comparing the images of toluidine blue staining and Raman mapping with different colors. In the choroid and pigment cell layer, the Raman spectrum had two peaks, corresponding to melanin. Some of the peaks of the Raman spectra obtained from the blood vessels in sclera and the photoreceptor layer were similar to those obtained from the purified hemoglobin and rhodopsin proteins, respectively. Our experimental protocol can distinguish different tissue components with Raman microscopy; therefore, this method can be very useful for examining the distribution of a biological structures and/or chemical components in rapidly frozen freeze‐dried tissue. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Fluorescence intensity is a poor predictor of saturation effects in two‐photon microscopy: Artifacts in fluorescence correlation spectroscopy
Authors: Wu Jianrong , Berland Keith
Published: March 2007

Fluorescence correlation spectroscopy (FCS) has become an increasingly important measurement tool for biological and biomedical investigations, with the capability to assay molecular dynamics and interactions both in vitro and within living cells. Information recovery in FCS requires an accurate characterization and calibration of the observation volume. A number of recent reports have demonstrated that the calibration of the observation volume is excitation power dependent, a complication that arises due to excitation saturation. While quantitative models are now available to account for these volume variations, many researchers attempt to avoid saturation issues by working with low nonsaturating excitation intensities. For two‐photon excited fluorescence, this is typically thought to be achievable by working with excitation powers for which the total measured fluorescence signal maintains its quadratic dependence on excitation intensity. We demonstrate that observing only the power dependence of the fluorescence intensity will tend to underestimate the importance of saturation, and explain these findings in terms of basic physical models. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Fluorescence microscopy: Established and emerging methods, experimental strategies, and applications in immunology
Authors: Petty Howard R.
Published: March 2007

Cutting‐edge biophysical technologies including total internal reflection fluorescence microscopy, single molecule fluorescence, single channel opening events, fluorescence resonance energy transfer, high‐speed exposures, two‐photon imaging, fluorescence lifetime imaging, and other tools are becoming increasingly important in immunology as they link molecular events to cellular physiology, a key goal of modern immunology. The primary concern in all forms of microscopy is the generation of contrast; for fluorescence microscopy contrast can be thought of as the difference in intensity between the cell and background, the signal‐to‐noise ratio. High information‐content images can be formed by enhancing the signal, suppressing the noise, or both. As improved tools, such as ICCD and EMCCD cameras, become available for fluorescence imaging in molecular and cellular immunology, it is important to optimize other aspects of the imaging system. Numerous practical strategies to enhance fluorescence microscopy experiments are reviewed. The use of instrumentation such as light traps, cameras, objectives, improved fluorescent labels, and image filtration routines applicable to low light level experiments are discussed. New methodologies providing resolution well beyond that given by the Rayleigh criterion are outlined. Ongoing and future developments in fluorescence microscopy instrumentation and technique are reviewed. This review is intended to address situations where the signal is weak, which is important for emerging techniques stressing super‐resolution or live cell dynamics, but is less important for conventional applications such as indirect immunofluorescence. This review provides a broad integrative discussion of fluorescence microscopy with selected applications in immunology. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Development management—values and partnerships
Authors: Thomas Alan
Published: March 2007

Values and multi‐organization partnerships are two crucial aspects of the contested field of development management. Their management crucially involves questions of authority, accountability, agency and validity. This Policy Arena includes two pairs of papers, one addressing the management of values and partnerships respectively in the context of NGOs and the second pair doing the same with respect to development management more broadly. They show that partnerships and values have in common that they cannot be managed by the imposition of a rationally defined programme of action but require indirect approaches such as steering, negotiation and looking for common ground. Copyright © 2007 John Wiley & Sons, Ltd.
Prions and peripheral nerves: A deadly rendezvous
Authors: Heikenwalder Mathias , Julius Christian , Aguzzi Adriano
Published: March 2007

The infectious particle causing transmissible spongiform encephalopathy (TSE), a fatal neurodegenerative disease of humans and animals, has been termed prion. Its major component is an aggregated variant of the cellular prion protein, PrPC. The main target of prion pathology is the central nervous system (CNS), yet most prion diseases are initiated or accompanied by prion replication at extracerebral locations, including secondary lymphoid organs, muscle and, in some instances, blood. How do prions travel from the periphery into the CNS? Is this an active or a passive process and does neuronal prion transport explain the long incubation times in prion diseases? Alternatively, if prion infectivity arises spontaneously in the CNS, as believed from sporadic Creutzfeldt‐Jakob patients, how do prions manage to travel from the CNS into the periphery (e.g., spleen, muscle) of the infected host? The mechanisms of neuronal prion transport from the periphery into the CNS or vice versa are heavily investigated and debated but poorly understood. Although research in the past has accumulated knowledge on prion progression from the periphery to the brain, we are far from understanding the molecular mechanisms of neuronal prion transport. © 2007 Wiley‐Liss, Inc.
Swedish amyloid precursor protein mutation increases phosphorylation of eIF2α in vitro and in vivo
Authors: Kim Hye‐Sun , Choi Yoori , Shin Ki‐Young , Joo Yuyoung , Lee Yong‐Kyu , Jung Sang Yong , Suh Yoo‐Hun , Kim Joung‐Hun
Published: March 2007

Swedish double mutation (KM670/671NL) of amyloid precursor protein (Swe‐APP), a prevailing cause of familial Alzheimer's disease (FAD), is known to increase in Aβ production both in vitro and in vivo, but its underlying molecular basis leading to Alzheimer's disease (AD) pathogenesis remains to be elucidated, especially for the early phase of disease. We have confirmed initially that the expression of Swe‐APP mutant transgene reduced cell viability via ROS production but this effect was eliminated by an anti‐oxidative agent, vitamin E. We also found that eukaryotic translation initiation factor‐2α (eIF2α), which facilitates binding of initiator tRNA to ribosomes to set on protein synthesis, was phosphorylated in cultured cells expressing Swe‐APP. This increase in phosphorylated eIF2α was also attenuated significantly by treatment with vitamin E. The finding that eIF2α became highly phosphorylated by increased production of Aβ was substantiated in brain tissues of both an AD animal model and AD patients. Although an increase in Aβ production would result in cell death eventually (in late‐phase of the disease), the altered phosphorylation state of eIF2α evoked by Aβ may account for the decreased efficacy of mRNA translation and de novo protein synthesis required for synaptic plasticity, and may consequently be one of molecular causes for impairment of cognitive functions exhibited in the early phase of AD patients. © 2007 Wiley‐Liss, Inc.
Interactions between neural membrane glycerophospholipid and sphingolipid mediators: A recipe for neural cell survival or suicide
Authors: Farooqui Akhlaq A. , Horrocks Lloyd A. , Farooqui Tahira
Published: March 2007

The neural membranes contain phospholipids, sphingolipids, cholesterol, and proteins. Glycerophospholipids and sphingolipids are precursors for lipid mediators involved in signal transduction processes. Degradation of glycerophospholipids by phospholipase A2(PLA2) generates arachidonic acid (AA) and docosahexaenoic acids (DHA). Arachidonic acid is metabolized to eicosanoids and DHA is metabolized to docosanoids. The catabolism of glycosphingolipids generates ceramide, ceramide 1‐phosphate, sphingosine, and sphingosine 1‐phosphate. These metabolites modulate PLA2activity. Arachidonic acid, a product derived from glycerophospholipid catabolism by PLA2, modulates sphingomyelinase (SMase), the enzyme that generates ceramide and phosphocholine. Furthermore, sphingosine 1‐phosphate modulates cyclooxygenase, an enzyme responsible for eicosanoid production in brain. This suggests that an interplay and cross talk occurs between lipid mediators of glycerophospholipid and glycosphingolipid metabolism in brain tissue. This interplay between metabolites of glycerophospholipid and sphingolipid metabolism may play an important role in initiation and maintenance of oxidative stress associated with neurologic disorders as well as in neural cell proliferation, differentiation, and apoptosis. Recent studies indicate that PLA2and SMase inhibitors can be used as neuroprotective and anti‐apoptotic agents. Development of novel inhibitors of PLA2and SMase may be useful for the treatment of oxidative stress, and apoptosis associated with neurologic disorders such as stroke, Alzheimer disease, Parkinson disease, and head and spinal cord injuries. © 2007 Wiley‐Liss, Inc.
Modulation of normal and altered hippocampal excitability states by septal networks
Authors: Colom Luis V. , Garrido‐Sanabria Emilio
Published: March 2007

The septal region of the basal forebrain plays a dual role: 1) It modulates hippocampal excitability, facilitating synaptic plasticity within hippocampal circuits. Through this mechanism, the septum facilitates diverse cognitive processes that involve hippocampal circuits. 2) Additionally, the septum maintains the hippocampal networks working within normal ranges, decreasing the probability of abnormal excitability states. Through this second mechanism, the septum prevents the occurrence of epileptic discharges. Thus, septal alterations may lead to both decreased cognitive functions and epilepsy, as observed in elderly patients affected with Alzheimer's disease. © 2007 Wiley‐Liss, Inc.
Nutrient dynamics—wind and water erosion at the village scale in the Sahel
Authors: Visser S. M. , Sterk G.
Published: March 2007

The loss of nutrients by wind erosion is generally attributed to losses by suspension, since suspension selectively removes the finest particles. However, because the main mass of sediment is moved by saltation during an event, the main mass of nutrients is also moved by saltation. Nutrient losses from one field during one wind erosion event can be as high as 73 per cent of the N and 100 per cent of the P needs for crop production.

Vegetated areas have a higher dust deposition because of the filtering effect of the vegetation and the reduction of drag forces causing a higher deposition. This refutes the general assumption that deposition of suspended dust is homogeneous for a larger area. In the Sahel, two types of dust can be distinguished, the Harmattan dust is richer in nutrients and regarded as a real input of nutrients. The convectional storm dust has a nutrient content comparable with the nutrient content of the dust fraction of the topsoil and can't be regarded as input of nutrients.

From research on nutrient losses by water erosion at the plot scale, it is concluded that nutrient erosion by water can cause serious losses of nutrients. But at the village scale, the losses are considerably smaller than at the plot scale.

Measurement and subsequent nutrient budget analyses around the village Dangadé in Burkina Faso indicated that this area is especially vulnerable for wind erosion by saltation transport. This demonstrates that in the Sahelian environment, the effect of wind erosion at the village scale can't be ignored. Copyright © 2007 John Wiley & Sons, Ltd.
Molecular Ordering of Vacuum‐Deposited 4,4′,4″‐tris(N‐(1‐naphthyl)‐N‐phenylamino) triphenylamine Thin Films
Authors: Oh Sung , Cho Young‐Rae , Choe Youngson , Park Dae‐Won
Published: March 2007

A thin film of vacuum deposited 1‐TNATA(4,4′,4″‐tris(N‐(1‐naphthyl)‐ N‐phenylamino)triphenylamine) is placed between indium tin oxide (ITO) electrode and a hole transporting layer (HTL) in OLEDs. The molecular ordering of 1‐TNATA thin film is obtained by thermal annealing and electromagnetic field. As‐deposited 1‐TNATA thin films were not molecularly ordered according to Raman spectra results. Thermal annealing after deposition lead to closer stacking of 1‐TNATA molecules and made the 1‐TNATA film well‐ordered. While thermal annealing at 110 °C, the average surface roughness decreased from 10.2 to 7.2 nm.
Synthesis and Optical Nonlinearity of Thermally Stable Polyimides Incorporated with Electro‐Optic Chromophore as Side Chain
Authors: Ju Hyun Kyung , Lim Jong Sun , Yoon Sung Cheol , Lee Changjin , Choi Dong Hoon , Park Seung Ku , Kim Dong Wook
Published: March 2007

We prepared thermally durable nonlinear optical (NLO) polymers, based on a polyimide attached with a NLO chromophore as a side‐chain. The polyimide with two aromatic hydroxyls in the repeat unit was prepared by condensation polymerization between 2,2‐bis(3‐amino‐4‐hydroxyphenyl) hexafluoropropane and oxydiphthalic anhydride in DMAc, followed by imidization reaction. Mitsunobu coupling was carried out to incorporate the NLO chromophore into the polyimide backbone, to yield the side‐chain polymer with a loading level of the chromophore up to 65 wt%. The thermal characterization of the polymer showed that the NLO polyimide had Tg at 168 °C and was thermally stable up to 370 °C. The polymer solution was spin coated on the ITO glass to produce an optical quality film. The electro‐optic coefficient of the film was obtained using 1.55 µm laser source, giving 31 pm/V with an electrical poling field of 1 MV/cm. The temporal stability of the polymer was confirmed over 330 h at 85 °C under nitrogen condition.
Different Flocculation Behaviors Between Ternary‐Amine Polystyrene Latex and Poly(styrenesulfonate): Probe Charge Effect
Authors: Lee Yun‐Ha , Choi Young‐Wook , Park Jaejung , Park Myeong‐Sam , Go Seung‐Yong , Kang Hak‐Hee , Paik Ungyu , Sohn Daewon
Published: March 2007

The flocculation of strong polyelectrolyte, poly(styrene sulfonate), (PSS) with ternary amine‐functionalized polystyrene particles was investigated by dynamic light scattering (DLS). Ternary amine particles that show stable dispersion in pH 10 undergo different flocculation in a low pH conditions. In pH 3 condition, particles present fast aggregation and irreversible process (coagulation) but in pH 7 solution particles show slow aggregation and reversible process (depletion‐induced flocculation). By adding strong polyelectrolyte, aggregation rapidly removed in pH 7 but retained some concentration (about 5 mg/L) in pH 3. The homogeneity exponent λ to characterize the different flocculation behaviors presents not only difference as a function of pH but also distinction as a function of concentration in pH 3.
Supramolecular Nanodevice Based on Helical Encapsulation of Photo/Electroactive Oligomers
Authors: Je Jongtae , Kim Oh‐Kil
Published: March 2007

Oligophenylenevinylene (OPV)‐based A‐D‐A chain chromophores were synthesized by symmetrically linking electron‐ or energy‐acceptor units through an alkyl spacer. Phto‐induced thru‐space electron/energy‐transfer (eT/ET) was investigated in the presence and absence of amylose encapsulation with respect to the spacer length (D‐A distance) and acceptor strength. Fluorescence quenching of the D‐A chromophores suggests that with the helical encapsulation, eT/ET have a discrete D‐A distance dependence while the free chromophores have mixed contributions, some from eT but largely from self‐quenching due to aggregation and/or solvent deactivation.
The Structure and Performance of Ionic Polymer‐Metal Composite Actuators Prepared via Electroless Plating Process Using Various Alcohols
Authors: Lee Jang‐Woo , Yoo Young‐Tai
Published: March 2007

Nafion™‐based ionic polymer‐metal composite (IPMC) actuators were fabricated using an electroless plating method. This study aims to improve the formation of Pt electrode in IPMCs employing various alcohols as media in the 1st deposition step instead of water. It was found that ethanol formed a thicker and well‐dispersed Pt electrode layer, whereas methanol and n‐propanol produced thinner Pt electrodes than water. Especially, IPMCs constructed in ethanol demonstrated a bending displacement comparable to conventional IPMCs processed in water without significant back relaxation attributable to a thicker and well‐dispersed Pt electrode and its high capacitance. It is also interesting to note that the IPMCs prepared in n‐propanol exhibited the fastest actuation response of all.
Surface Modification via Plasma Polymerization of Allylamine for Antibody Immobilization
Authors: Basarir Fevzihan , Cuong Nguyen , Song Woo‐Keun , Yoon Tae‐Ho
Published: March 2007

Continuous wave and pulsed plasma polymerization coatings of allylamine were investigated for antibody immobilization as a function of plasma power, monomer pressure and treatment time, and duty cycle. Conditions were optimized by evaluating the surface amine density of plasma polymer coated samples before and after aging in dry ethanol for 3 hrs. In addition, plasma polymer coatings were characterized by contact angle analyzer, α‐step, and FT‐IR/ATR. The continuous wave plasma polymerization provided amine density of 4.8 molecules/nm2 at the optimum condition of 20 W, 1 min, and 60 mTorr, while the pulsed plasma polymerization coating resulted in further increased amine density to 5.2 molecules/nm2 at the duty cycle of 60/100.
Novel Biodegradable Molecularly Imprinted Polymers Based on Poly(3‐hydroxybutyrate)
Authors: Oh Won‐Gyun , Kim Beom Soo
Published: March 2007

Novel biodegradable molecularly imprinted polymers (MIP) based on poly(3‐hydroxybutyrate) (PHB) were prepared and characterized. Low molecular weight PHB diol was prepared from bacterial PHB, and was used to synthesize acrylate end‐capped PHB macromer. The synthesis of hydroxyl‐telechelic PHB and acrylate end‐capped macromer was confirmed using FT‐IR and 1H NMR. PHB macromer was used to prepare biodegradable crosslinked networks by photopolymerization with functional monomer (methacrylic acid) and a model template (theophylline). The theophylline‐imprinted polymer showed higher binding capacity for theophylline than non‐imprinted polymer (NIP). The data of theopylline binding into the theopylline‐imprinted polymer correlated well with the Scatchard plot. The equilibrium binding constant (KE) and the total number of bound sites of MIP ([PS]total) were 7.1 × 103 M−1 and 18.5 µmol/g, respectively, which were estimated from the negative slope and intercept in the Scatchard plot.
Synthesis and Helicity Induction of Poly(phenylacetylene)s Bearing Crown Ether Pendants. Reversible On‐Off Switching of the Induced Helical Chirality Tunable with Temperature
Authors: Sakai Ryosuke , Kakuchi Toyoji
Published: March 2007

Cis‐transoidal poly(phenylacetylene)s bearing 15‐crown‐5 (2a) and 18‐crown‐6 (2b) were prepared by stereoselective polymerization using Rh(nbd)BPh4. In the circular dichroism (CD) spectrum of 2a in the presence of the perchloric acid salt of L‐phenylglycine (L‐Pgly· HClO4), a characteristic induced CD (ICD) was observed in the absorption range corresponding to the polymer backbone. On the contrary, the 2b/L‐Pgly · HClO4 system did not show such an ICD spectrum. The ICD intensity of the 2a/L‐Pgly · HClO4 system drastically depended on temperature, i.e., the ICD disappeared at 30 °C or higher. Thus, the on‐off switching of the ICD of 2a was controllable by either the temperature modulation or the doping/undoping process of the chiral guest.
Effects of Biodegradable Triblock Copolymers on the Microencapsulation of Ascorbic Acid‐2‐Glucoside in W1/O/W2 Multi‐Emulsions
Authors: Cho Heui Kyoung , Cho Jin Hun , Cheong In Woo
Published: March 2007

A skin‐active functional material, AA2G (ascorbic acid‐2‐glucoside, W1 phase), was encapsulated via a stepwise emulsification method using PEO‐PLGA‐PEO and PEO‐PCL‐PEO biodegradable triblock copolymers as wall materials. The emulsion stability of the W1/O/W2 multi‐emulsions was observed using a ferroxyl test method and on‐line turbidity analysis for a short period of time. The morphology of the multi‐emulsions was observed using the laser confocal and optical microscopes. The use of copolymers in W1 phase was found to be more effective. The copolymers decreased the size of the multi‐emulsions and enhanced emulsion stability.
Preparation of Polymer/Drug Nano‐ and Micro‐Particles by Electrospraying
Authors: Park Chul Ho , Kim Min Young , Yoo Ji Youn , Kim Ki‐Hyun , Lee Jong‐Chan , Lee Jonghwi
Published: March 2007

The surface energy control capability of electrohydrodynamic force provides electrospraying with various potential advantages such as simple particle size control, mono‐dispersity, high recovery, and mild processing conditions. Herein, particle fabrication of biodegradable polymers using electrospraying was developed. The major processing parameters such as the conductivity of spraying liquids, flow rate, etc., were examined to obtain the successful apparatus configuration of electrospraying. The choice of a consolidation medium was critical in obtaining well‐dispersed nanoparticles. When triphenylphosphate aqueous solution was employed as a consolidation medium, its concentration was not an effective parameter to control the aggregation of primary particles. When organic solvents were employed, the processing windows of electrospraying were relatively narrow than water‐based systems.
Heparin Immobilized Small Intestinal Submucosa for Cardiovascular Applications
Authors: Jee Kyoung Soo , Bae Jin Woo , Shin Jae Seung , Han Dong Keun , Park Ki Dong
Published: March 2007

A novel chemical modification of biological tissue was developed by the immobilization of heparin to small intestinal submucosa (SIS) using glutaraldehyde (GA). Heparinized SIS tissue was characterized by measuring in vitro plasma protein adsorption, platelet adhesion, in vitro fibroblast attachment, and in vivo calcification. Lower protein adsorption and platelet adhesion were observed on heparinized SIS than non‐modified SIS. The attachment of human dermal fibroblast on the heparinized SIS was significantly increased, and the amount of calcium deposited on the modified SIS was much less than fresh SIS. These results demonstrated that heparin immobilized SIS can be applied as a novel bioprosthesis for a variety of cardiovascular applications.
The Effects of Co‐Immobilization of Epidermal Growth Factor and Adhesion Factor on the Proliferation of Ligament Cell
Authors: Park Yong‐Soon , Seo Young‐Kwon , Lee Hwa‐Sung , Kwon Soon‐Yong , Park Jung‐Keug
Published: March 2007

The epidermal growth factor and cell adhesion factor were co‐immobilized on a tissue culture plate to allow the proliferation of human ligament cells. The co‐immobilized surfaces were prepared by irradiating a photo‐reactive polypeptide containing azidophenyl‐derivatized side‐chains with UV. The immobilized cell adhesion factor induced initial cell adhesion on the surfaces, and the immobilized cell growth factor appeared to induce cell proliferation. The ligament cells proliferated on the EGF‐immobilized plate until 10 days post‐culture. The co‐immobilization of the epidermal growth factor appears to be an effective method for healing an anterior cruciate ligament through the rapid proliferation of ligament cells.
Radial Flow Type Bioreactor for Bioartificial Liver Assist System Using PTFE Non‐Woven Fabric Coated with Poly‐amino Acid Urethane Copolymer
Authors: Miskon Azizi , Sasaki Noriko , Yamaoka Tetsuji , Uyama Hiroshi , Kodama Makoto
Published: March 2007

Recently, various types of hybrid bioartificial liver using the porcine hepatocytes have been widely studied but their clinical usage is limited by various difficulties. One of the most efficient bioreactor is the radial flow system equipped with silicon oxygenator. Here, our bioreactor system provides the oxygenator and the radial flow of medium that supplies the nutrient efficiently. The adhesion and growth of the cultured hepatocytes are greatly improved by using polytetrafluoroethylene (PTFE) non‐woven fabrics coated with poly‐amino acid urethane copolymer (PAU). Its functional activities were established after being kept for one week at the high value in this bioreactor system. These results indicate that, PTFE non‐woven fabric and radial flow technique is proven to be the best bioreactor for a hybrid artificial liver support system (HALS).
Synthesis and Evaluation of PEG Derivatives for Crosslinking Cells
Authors: Ito Michiko , Tateishi Tetsuya , Taguchi Tetsushi
Published: March 2007

The objective of this study is synthesis, characterization, and evaluation of a novel crosslinker to form spheroids. Our approach was based on the crosslinking of cell membrane using a polymeric crosslinker via hydrophobic interaction. A crosslinker poly(ethylene glycol) derivative with oleyl groups as hydrophobic group at both ends was synthesized, and then characterized with gel permeation chromatography and Fourier‐transform infrared spectroscopy. Furthermore, cell culture experiments were performed to confirm spheroid formation. Spheroids were successfully obtained when the crosslinker was added to cell suspension. This polymeric crosslinker was useful in the formation of cell spheroid.
Electrochemical Properties of PVDF‐Based Nanocomposite Solid Polymer Electrolytes
Authors: Jeong Soo‐Kyeong , Lee Yu‐Jin , Jo Nam‐Ju
Published: March 2007

Poly(vinylidene fluoride) (PVDF)‐based nanocomposite solid polymer electrolytes (NSPEs) were prepared and ion conduction property was investigated according to the filler content. The organically modified clay (Cloisite®15A, C15A) was used as a filler because it has had a good compatibility with PVDF. X‐ray diffraction measurement revealed the dispersion of C15A in PVDF and the states of exfoliation and intercalation of C15A were also observed by transmission electron microscopy. In order to confirm the ion conduction properties of NSPEs with LiCF3SO3, ac impedance analyzer and FT‐IR spectrometer were used. The highest ionic conductivity was appeared in NSPE containing 5wt% of C15A and the maximum conductivity was 1.04 × 10−3 S cm−1. And the improvement of electrochemical stability of NSPEs by adding C15A was confirmed.
Electrochemical Properties of PEO‐Based Polymer Electrolytes Blended with Different Room Temperature Ionic Liquids
Authors: Kim Yeon Hwa , Cheruvally Gouri , Choi Jae Won , Ahn Jou Hyeon , Kim Ki Won , Ahn Hyo Jun , Choi Doo Seong , Song Choong Eui
Published: March 2007

Polymer electrolyte (PE) based on poly(ethylene oxide)‐lithium bis(trifluoromethane sulfonyl)imide (PEO‐LiTFSI) was blended with three room temperature ionic liquids (RTILs), namely 1‐butyl‐3‐methylimidazolium bis(trifluoromethane sulfonyl)imide (BMITFSI), 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIBF4) and 1‐butyl‐3‐methylimidazolium trifluoromethanesulfonate (BMICF3SO3) with a view to enhance the room temperature ionic conductivity to acceptable levels for use in lithium batteries. The incorporation of 80 parts by weight (pbw) of the RTILs in 100 pbw of PEO‐LiTFSI resulted in enhanced ionic conductivity, the effect being more pronounced at lower temperatures. Evaluation of electrochemical properties showed that PEs with RTILs exhibit an electrochemical stability window between −1.0 V and 4.5 V vs Li/Li+ and good reversibility of redox reactions on cycling. The optimum results were obtained with the incorporation of BMITFSI in the PE, which exhibited a low and stable interfacial resistance on lithium metal.
Synchronous Crosslinking Imidized Polymer Electrolytes Having Fully Interpenetrating Polymer Networks (Full‐IPNs) Structure for Application in Membrane Fuel Cell
Authors: Kim Sang‐Gyun , Ahn Hae‐Ryun , Min Da‐Young , Nam Seung‐Eun , Lee Kew‐Ho
Published: March 2007

Polymer electrolyte films having fully interpenetrating polymer networks (Full‐IPNs), composed of styrene‐maleic anhydride alternating copolymer (PSMAn) and isobutylene‐maleic anhydride alternating copolymer(PisoMAn), have been prepared by using 2,2′‐benzidinedisulfonic acid(BDSA) as the imidizing crosslinker. The resulting films were characterized by using TGA, EA, IEC, water uptake, and proton conductivity. The purpose of this work deals with the synchronous crosslinking imidization reaction of between polymers as a synthetic method, in order to prepare novel heat‐resistant polymer electrolytes for application in membrane fuel cell.
Polymer Electrolyte Membranes Based on Room Temperature Ionic Liquid: 2,3‐Dimethyl‐1‐octyl imidazolium hexafluorophosphate (DMOImPF6)
Authors: Sekhon S. S. , Lalia B. S. , Kim C. S. , Lee W. Y.
Published: March 2007

Room temperature ionic liquid: 2,3‐dimethyl‐1‐octylimidazolium hexafluorophosphate (DMOImPF6) has been incorporated in polyvinylidenefluoride ‐co‐ hexafluoropropylene (PVdF‐HFP) to develop non‐aqueous polymer electrolyte membranes. The conductivity of polymer electrolyte membranes depends upon the composition of ionic liquid and maximum conductivity of 1.35 × 10−3 S/cm at 120 °C has been observed. The addition of plasticizers has been found to enhance the conductivity of polymer electrolytes by one order of magnitude which depends upon the dielectric constant of plasticizer.
Study on PEFC Membrane Based on Crosslinked FEP Using EB‐Grafting
Authors: Matsuura Akio , Kakigi Tomoyuki , Sato Yukiko , Fujii Kazuki , Mitani Naohiro , Li Jingye , Oshima Akihiro , Washio Masakazu
Published: March 2007

Polymer electrolyte fuel cell (PEFC) membranes based on crosslinked tetrafluoroethylene‐co‐hexafluoropropylene (FEP) have been fabricated by pre‐irradiation grafting method. The chemical structures of crosslinked materials have been analyzed by Differential Scanning Calorimeter (DSC) and 19F solid‐state Nuclear Magnetic Resonance (NMR) spectroscopy. The radical yields of irradiated samples were measued by Electron Spin Resonance (ESR), and the mechanism of grafting reaction has been discussed. The styrene grafted materials were sulfonated by chlorosulfonic acid. The ion exchange capacity of the obtained sulfonated crosslinked FEP (S‐FEP‐X) showed 2.0 to 2.4 meq/g, which were 2.2 to 2.7 times higher than that of Nafion®112. Glass transition temperatures (Tg) of S‐FEP‐X were almost independent on crosslinking dose of FEP, and show about 96 °C, which are slightly higher than that of Nafion®. The electrochemical properties of the membranes have been measured, and cell performances of them have been evaluated. Ionic conductivities (ICs) of S‐FEP‐X are 1.2 to 1.6 times higher than that of Nafion®. The higher network densities gave the higher open circuit voltage (OCV). The power density of S‐FEP‐600kGy was about 10% higher than that of Nafion® at 500mA/cm2. Thus, the obtained sulfonated membranes can be expected to apply for high efficiency PEFC.
Electrochemical Polymerization of Aniline by Current Pulse Method in the Presence of m‐Aminobenzoic Acid in Chlorhydric Acid Solution
Authors: Binh Phan Thi
Published: March 2007

Electrical and structural properties of polyaniline powder doped by chloride and m‐aminobenzoic acid on graphit electrode through current pulse method have been investigated by conductivity measurement, infrared spectroscopy, thermal analysis and scanning electron microscopy. The infrared spectra for the both products showed the clear presence of benzoid and quinoid ring vibrations at 1567 cm−1 and 1489 cm−1, respectively. The microstructural observation by scanning electron microscopy showed a knitted morphology of polyaniline doped by m‐aminobenzoic acid the conductivity of which was found 0.635 S/cm, higher than that of polyaniline synthesized in chlorhydric acid solution (0.368 S/cm). The conductive materials were decomposited at about 380 degree.The detail results will be discussed below.
Synthesis and Characterization of Al(OH)3/Polystyrene Nanocomposite Latex Particles by Emulsion Polymerization
Authors: Park Eun Ju , Heo Hoon , Lim Kwon Taek
Published: March 2007

The inorganic/organic core‐shell type nanocomposite particles of Al(OH)3/PSt were synthesized through the emulsion polymerization of styrene (St, shell monomer) with ammonium persulfate (APS, initiator), polyoxyethylene (50) nonyl phenyl ether (NP‐1050, nonionic surfactant), and ammonium (POE) alkyl arylether sulfate (EU‐S133D, anionic surfactant) in the presence of the modified Al(OH)3 particles. The improved compatibility of Al(OH)3 surface with St achieved by the modification with 3‐(trimethoxysilyl) propyl methacrylate (γ‐MPS) enabled to form a polymer shell around the mineral particles. The structure of nanocomposites prepared from different feed ratio of Al(OH)3/St was investigated by scanning (SEM) and transmission (TEM) electron microscopies.
Functionalization of Multi‐Walled Carbon Nanotubes with Poly(2‐ethyl‐2‐oxazoline)
Authors: Tan Soon Huat , Goak Jeung Choon , Lee Naesung , Kim Jeong‐Yeol , Hong Sung Chul
Published: March 2007

Multi‐walled carbon nanotubes (MWCNTs) were successfully functionalized with water‐soluble poly(2‐ethyl‐2‐oxazoline) (PEOX) through a polymer wrapping process. Pristine MWCNTs were first treated with nitric acid (HNO3) at 120 °C for 24 hours. The resulting carboxylated MWCNTs were then mixed with 10 wt.% PEOX in ethanol, followed by sonication using a horn‐type sonicator for 30 min and stirring at room temperature for 24 hours. Thereafter, unreacted free polymer was washed out repeatedly by centrifugation with an excess amount of ethanol. Scanning electron microscopy exhibited that the diameter of MWCNTs increased approximately by 10 nm after the functionalization of MWCNT with PEOX. Thermogravimetric analysis showed that approximately 15 wt.% polymer was incorporated in the functionalized MWCNTs. The functionalized MWCNTs gave excellent and stable dispersion in water as well as other organic solvents such as ethanol and DMF.
Fabrication of a Nano‐Porous Polyoxazoline‐Coated Tip for Scanning Probe Nanolithography
Authors: Lee Jae‐Hyuck , An Young‐Chul , Choi Dong‐Sik , Lee Myoung‐Jae , Kim Kyung‐Min , Lim Jung‐Hyurk
Published: March 2007

A nano‐porous polyoxazoline‐coated silicon tip was developed by ring opening polymerization of 2‐methyl‐2‐oxazoline. The tip surface modified with the nano‐porous polyoxazoline has pore sizes from 30 nm to 100 nm, which can easily absorb large‐molecular‐weight biomolecules in their pores. In combination with dip‐pen nanolithograpy (DPN) technique, this can generate protein nanostructures 60 times faster than what one can obtain with the conventional silicon tip. We discuss the fabrication of the nano‐porous polymers on the surface and how to use this novel tip for scanning probe lithography‐based nanopatterning of biomolecules.
Model Supported Morphology Control of Electrospray Deposited Poly(vinylidene fluoride) Film
Authors: Rietveld Ivo B. , Kobayashi Kei , Yamada Hirofumi , Matsushige Kazumi
Published: March 2007

Preparation of polymer films with electrospray deposition has been investigated. Morphologies of poly(vinylidene fluoride), prepared under a range of different conditions, have been imaged with AFM. To generalize the conditions under which a particular morphology appears, a model has been used. The model incorporates the parameters that determine droplet size and droplet evaporation in the electrospray deposition process. With the model, film morphology has been shown to depend on the droplet volume at impact, available surface area on the substrate and rate of solvent evaporation from the film. With this information, the model can predict the film morphology under many different spray conditions. This has been demonstrated by determining and predicting the conditions under which PVDF displays the smoothest films.
Fully Aliphatic Polyimides – Influence of Adamantane and Siloxane Moieties
Authors: Mathews Anu Stella , Kim Il , Ha Chang‐Sik
Published: March 2007

Series of fully aliphatic polyimides were prepared from cyclobutane‐ 1,2,3,4‐tetracarboxylic dianhydride and aliphatic diamines. The variations of the basic properties of these polyimides as a result of the incorporation of adamantyl and siloxane moieties are examined. The structure of the polyimides where confirmed by FT‐IR spectroscopy. It was found that polyimides with appropriate ratio of adamantane and siloxane groups showed excellent solubility, good thermal stability, high glass transition temperature, low dielectric constant and beneficial transparencies.
Synthesis of Polycarbonate‐Poly(methyl methacrylate) Copolymer via Sonochemical Polymerization of Methyl Methacrylate in Polycarbonate Solution
Authors: Choi Mikyung , Lee Kyunghee , Lee Juhyun , Kim Hyungsu
Published: March 2007

Methyl methacrylate (MMA) was polymerized in the presence of polycarbonate (PC) by ultrasonic irradiation‐initiated polymerization. The resulting products consisted of mixtures of homopolymers of poly(methyl methacrylate) (PMMA), PC and PC‐PMMA copolymer because of the homopolymerization of MMA itself and copolymerization with macroradicals of PC. Formation of the PC‐PMMA copolymer was confirmed by FTIR analysis of the reaction products after a proper extraction of free PMMA from the mixture. In order to verify the effectiveness of the PC‐PMMA copolymer as a compatibilizer for PC/styrene‐co‐ acrylonitrile (SAN) blend, 5 phr of PC‐PMMA was added during melt mixing of PC/SAN in a batch mixer. It was found from the investigation of morphology and rheological properties that interphase of SAN and PC was fortified by numerous ligaments of PC‐PMMA copolymer, which resulted in increase of melt viscosity and storage modulus of the blend.
Synthesis of Diblock Codendrimers by Fusion of the Fréchet‐Type and the PAMAM Dendrons
Authors: Lee Jae Wook , Kim Jung Hwan , Han Seung Choul , Kim Woo Roi , Kim Byoung‐Ki , Kim Ji Hyeon , Huh Do‐Sung , Shin Won Suk , Jin Sung‐Ho
Published: March 2007

Several diblock dendrimers were synthesized by fusion between the propargyl functionalized Fréchet‐type polyether and the azide functionalized Tomalia‐ type PAMAM dendrons. This was based on the click chemistry protocol, the copper‐catalyzed cycloaddition reaction between an alkyne and an azide. The diblock dendrimers were characterized by 1H and 13C NMR spectroscopy, IR spectroscopy, and mass spectra as well as GPC analysis.
Polystyrene Microgel Amphiphilies with Saccharide to Achieve a Fullerene‐Coating on a Hydrophilic Surface
Authors: Narumi Atsushi
Published: March 2007

Synthesis of a polystyrene (PSt) microgel with glucose and maltohexaose, in which a good coating property was combined with an excellent hydrophilic property, is described. The glycoconjugated PSt microgel showed the ability to solubilize fullerene in aqueous solution, thus having a potential application to achieve the coating of a functional but incompatible compound, such as fullerene due to the lack of polarity, on the surface of various hydrophilic materials.
Template Polymerization of Multi‐Vinyl Monomer with Poly(2‐hydroxyethyl methacrylate) Backbone
Authors: Saito Reiko , Yokoi Kazuhiro , Iijima Yuki
Published: March 2007

In order to investigate the propagation of polymerization in the template with linear polymer chain, ATRP of methacryloyl type multi‐vinyl monomers of pol(2‐hydroxyethyl methacrylate) backbone with and without styryl groups on the chain ends was carried out. Change of hydrodynamic radii of products and conversion of vinyl group were analyzed by GPC and FT‐IR, respectively.When the multi‐vinyl monomer concentration was less than 0.3 wt%, gelation was completely hindered. The kinetic plots of polymerization of multi‐vinyl monomers with and without styryl group on the chain ends agreed well.
Design of Latent Accelerators for Thermally Latent (Poly)addition of Epoxide with Hemiacetal Ester
Authors: Endo Takeshi , Komatsu Hiroyuki , Ochiai Bungo , Hino Tetsuo
Published: March 2007

This article describes thermally latent addition of epoxides and hemiacetal esters using novel latent accelerators. As latent accelerators for the thermally‐controlled (poly)addition, we desinged schiff‐base zinc chloride complexes (ZnCl2/1R) and salen‐zinc complex (Zn/2). This latent reaction takes place via the reaction of epoxides and carboxylic acids produced from thermal dissociation of hemiacetal esters at moderate temperatures. Use of bifunctional monomers give the corresponding polyesters with side chains bearing acetal and hydroxyl group through the polymerization using the catalysts with tuned Lewis acidities. Zn/2 shows a sharper temperature dependence than ZnCl2/1H.
Temperature‐Responsive Surface Coatings Based on Poly(methylsilsesquioxane)‐hybrid Polymers
Authors: Kessler Daniel , Théato Patrick
Published: March 2007

The present paper presents a new method to build up temperature‐responsive surfaces. First a poly(silsesquioxane)‐block‐poly(N‐isopropyl‐acrylamide) (PMSSQ‐b‐PNIPAM) was successfully synthesized using RAFT polymerization. Spin‐coating or dip‐coating of PMSSQ‐b‐PNIPAM onto glass surfaces resulted in temperature‐responsive surfaces. Surface ATR FT‐IR measurements proofed the successful surface modification using PMSSQ‐b‐PNIPAM. IR fine structures of PNIPAM and PMSSQ could be assigned, respectively. In capillary rise experiments a change of the meniscus height measured at temperatures below or above LCST was observed, indicating a different wetting behavior. Thus, a simple spin‐ or dip‐coating step results in a clean and temperature‐responsive surface.
Enthalpy‐Entropy Compensation in Aggregation of Poly(styrene‐co‐sodium methacrylate) Ionomers in Aqueous Solution
Authors: Yu Jeong‐A , Oh Sung‐Hwa , Park Yu‐Ri , Kim Joon‐Seop
Published: March 2007

Spectroscopic methods were employed to evaluate the thermodynamics of aggregates formation of P(S‐co‐MANa) in aqueous solution containing a trace of DMF(0.2 mol%) using pyrene as an optical probe. The mol %s of methacrylate unit in poly(styrene‐co‐sodium methacrylate)[P(S‐co‐MANa)] were 3.6, 5.0, 6.2 and 9.4. Measurements were made at a series of temperatures in the range 10–80 °C. Based on the temperature dependence of the critical aggregation concentration (CAC) and by the use of van't Hoff equation, thermodynamic parameters were calculated. At low temperature the aggregation is accomplished by a large positive entropy change and a small negative enthalpy changes. As the temperature increases, the magnitude of entropy change becomes smaller and the enthalpy change is more exothermic. Moreover, the changes in enthalpy and entropy compensate each other for all samples we have studied, and the compensation temperature was ∼320 K.
Soluble Asymmetric Perylene Derivatives for Organic Solar Cells
Authors: Do Jung Yun , Kim Bong Gun , Kwon Ji yun , Shin Won suk , Jin Sung‐Ho , Kim Young‐Inn
Published: March 2007

Organic acceptor material has been developed based on soluble perylene derivative for an organic solar cell. Asymmetric perylene derivatives with an imide and an imidazole group produce absorption spectra close to poly(3‐hexylthiophene) (P3HT) as a donor material. The frontier energy levels of the perylene derivatives can adjust to reasonable charge transmission within a blended polymer layer through the introduction of substituents such as alkoxy, nitro and alkoxycarbonyl group. The nitro group unlike the others leads to the exceeding decrement of the frontier energy levels, which would be unfavorable for efficient charge transfer. Cyclic voltammetry analysis is performed to determine the energy levels of the perylene derivatives.
31P Solid‐State NMR Characterization of Poly(vinylphosphate‐black‐styrene) for DMFC Membrane
Authors: Park Tae‐Joon , Kim Sang Hun , Li Guang Hua , Cho Chang Gi , Kim Yongae
Published: March 2007

In an attempt to develop direct methanol fuel cell (DMFC) membrane with low methanol permeability, we synthesized successfully poly(vinyl phosphate‐ b‐styrene) copolymers from poly(vinyl alcohol‐b‐styrene) by reaction with phosphorus oxychloride and subsequent hydrolysis. We obtained the ratio of the differently bound phosphorus by 31P Solid‐state NMR Spectroscopy because the majority of block copolymer is not soluble or does not make homogeneous solution in a NMR solvent. The total amount of acid groups as well as the ratio of singly and doubly bound phosphorus by 31P Solid‐state NMR and pH titration was slightly different due to the cross‐linked nature of the sample. Therefore, solid‐state NMR spectroscopy is the most powerful technique to characterize cross‐linked polymers like DMFC membrane.
DNA Dynamics under Turbulent Flow
Authors: Lim Sung Taek , Hong Cheng Hai , Choi Hyoung Jin
Published: March 2007

Using high molecular weight DNAs (λ‐and calf‐thymus (CT) DNAs), we investigated their flow characteristics under turbulence in a rotating disk geometry. By putting emphasis on the effect of CT‐DNA concentration, its turbulent drag reduction (DR) characteristics were compared with that of λ‐DNA based on both DR efficiency and mechanical degradation under turbulence. Addition of spermidine into the turbulent flow as a condensing agent showed abrupt change of the DR efficiency of λ‐DNA in a turbulent flow.
Surface Electronic Structures of Polythiophene Derivatives
Authors: Hao X. T. , Hosokai T. , Mitsuo N. , Kera S. , Sakamoto K. , Okudaira K. K. , Ueno N.
Published: March 2007

We report the surface electronic structures of polythiophene derivatives (including polythiophene, poly(3‐butylthiophene), poly (3‐hexylthiophene)(P3HT)) thin films observed by ultraviolet photoelectron spectroscopy and Penning ionization electron spectroscopy. He*‐impact‐surface‐modification was applied on the P3HT surface to control the distribution of the electron density.