bluuebunny/crossref_metadata_2025 huggingface dataset:
SECOND HYPERPOLARIZABILITIES OF MOLECULAR AGGREGATES: INTERMOLECULAR ORBITAL-INTERACTION AND SPIN-CONFIGURATION EFFECTS
Authors: NAKANO MASAYOSHI , YAMADA SATORU , TAKAHATA MASAHIRO , YAMAGUCHI KIZASHI
Published: September 2003

Toward an understanding of intermolecular-interaction effects on the third-order nonlinear optical properties of nanostructured molecular aggregates, we investigate the longitudinal second hyperpolarizabilities (γ) of model dimers composed of neutral ( C 5 H 7) and charged [Formula: see text] monomers using ab initio molecular orbital methods. It is found that π–π orbital interaction in the stacking direction remarkably affects the γ values of dimers, while the difference in spin configuration hardly causes significant changes in γ for the present models due to weak exchange interactions between monomers.
FABRICATION OF CdS DOT ARRAY USING POLYMER HONEYCOMB TEMPLATE
Authors: FUKUDA NOBUKO , SHIMOMURA MASATSUGU
Published: September 2003

We fabricated periodic structures of CdS using honeycomb films consisting of an amphiphilic copolymer as a template. The honeycomb film using an amphiphilic copolymer was fabricated on the water surface under highly humid condition and was then transferred onto a solid substrate. The pore size in the honeycomb film was ca. 5 μm. The CdS nanoparticles were synthesized using a gelatin as an inhibitor of rapid nuclear growth and then the gelatin was removed by decomposition using an enzyme. The CdS particles were introduced into pores of the honeycomb film by casting, dipping, and electrochemical deposition. Dipping the honeycomb film into CdS suspension under ultrasonication, periodic deposition of CdS particles in the honeycomb holes was achieved. The CdS -honeycomb film composite was calcinated at 450°C for 30 min in order to remove organic moiety. After calcination, periodic arrangement of porous CdS dots with diameter of 3–5 μm was partially formed. The CdS dots are applicable to photoelectrochemical and optical devices such as a photodiode.
FORMATION OF GOLD NANOPARTICLES/OLIGOTHIOPHENE DITHIOLS COMPOSITE THIN FILMS BETWEEN MICROGAPPED GOLD ELECTRODES AND THEIR ELECTRONIC PROPERTIES
Authors: MAEDA SEISUKE , OGAWA TAKUJI
Published: September 2003

We have studied the construction and electronic characteristics of a series of devices made from gold microgap electrodes, gold nanoparticles and conjugated oligothiophene dithiols. The formations of gold nanoparticle/oligothiophene dithiol composites on gold surface were monitored by quartz crystal microbalance (QCM) using gold electrode coated crystal oscillator. The formation speed was the fastest for terthiophene dithiol followed by hexathiophene and nanothiophene dithiols, the latter two showed almost the same formation speed. The current–voltage (I/V) curves of these devices were measured at various temperatures to show that at high temperature (>200 K) they were almost straight line; at lower temperature they became parabolic, and at 4 K a completely blocked region appeared between -12 to +12 V. We attributed the parabolic I/V curve to a tunneling mechanism and the blocked region to the Coulomb blockade phenomena.
PREPARATION OF ZnO NANOPARTICLES BY PRECIPITATION/MECHANOCHEMICAL METHOD
Authors: ZHANG SHICHENG , CHI LEI , LI XINGGUO
Published: September 2003

The ZnO nanoparticles were synthesized by using a combination of precipitation and mechanical milling. Basic zinc carbonate precursor was prepared by precipitation process using zinc sulfate as the starting material. Under the mechanochemical effect, parts of the basic zinc carbonate were transformed into ZnO . In the closed system of milling, in order to produce pure ZnO nanoparticle phase, further heat processing was needed. But the ultimate ZnO particles were more uniform and the particle size distribution was narrower. The effects of mechanical milling process on properties of ultimate ZnO particles were also investigated.
IMPRINT OF HONEYCOMB PATTERN ON PDMS ELASTOMER
Authors: OHZONO TAKUYA , FUKUDA NOBUKO , NISHIKAWA TAKEHIRO , SHIMOMURA MASATSUGU
Published: September 2003

Recently a method that utilizes the condensation of micrometer-sized water droplets on evaporating solutions of polymers has been reported for the preparation of porous thin films with fine hexagonal periodicity, honeycomb films. Here we report a method for imprinting a honeycomb pattern on the PDMS (poly(dimethyl siloxane)) elastomer. For the preparation of the honeycomb film, a benzene solution of amphiphilic copolymer was cast at high atmospheric humidity. On the film the PDMS precursor was poured and cured. The cured PDMS with the honeycomb film was peeled from the slide glass. The PDMS was rinsed with the solvent to remove the honeycomb film. The exposed PDMS surface was observed using SEM and AFM. The pattern-imprinted PDMS surface can be used as a template for patterning of materials, which are difficult to produce a honeycomb pattern by the conventional method described above. Here, we show some examples of such honeycomb-originated structures composed of polymers or nanoparticles, which were fabricated using the pattern-imprinted PDMS. The present study shows an example of the secondary uses of the self-organized structures for the cost-saving micro/nanofabrication of various materials.
MANIPULATION OF CARBON NANOTUBE BUNDLES WITH CONTACT MODE ATOMIC FORCE MICROSCOPY
Authors: SHEN ZIYONG , LIU SAIJIN , HOU SHIMIN , XUE ZENGQUAN , GU ZHENNAN
Published: September 2003

The cutting and splitting of carbon nanotube bundles were realized with an atomic force microscopy (AFM) in contact mode. The results of manipulating were found depending on the tip–bundle interaction and bundle–substrate interaction. With an optimal force load of AFM tip, the lateral force applied on the nanotube bundle could overcome the adhesive interaction between nanotubes within the bundle, consequently separating individual nanotubes from the bundle. The threshold of the tip force load was found to be ~45 nN in our experiments. This technique provides new possibilities for the controllable manipulation of carbon nanotubes.
SYNTHESIS OF CdTe NANOPARTICLE BY γ-IRRADIATION
Authors: JO SONG JA , KANG YOUNG SOO
Published: September 2003

Semiconductor CdTe nanoparticles were synthesized by the γ-irradiation of Cd ion complex at room temperature. Cd-olate complex was reacted with aqueous NaHTe solution. The products were investigated by X-ray Powder Diffraction (XRD) and Transmission Electron Microscopy (TEM). The optical properties of CdTe were investigated with UV-vis and photoluminescence (PL) spectra.
FABRICATION AND CHARACTERIZATION OF QUINACRIDONES NANOCRYSTALS BY HIGH-TEMPERATURE AND HIGH-PRESSURE CRYSTALLIZATION METHOD
Authors: LI BO , KASAI HITOSHI , OIKAWA HIDETOSHI , OKADA SHUJI , ARAI KUNIO , NAKANISHI HACHIRO
Published: September 2003

The high-temperature and high-pressure liquid (HTPL) crystallization method was proved to be effective to fabricate nanocrystals of quinacridone and its dimethyl derivative. The quinacridone nanocrystals were spherical shape and monodispersed with the average size of around 50 nm, respectively. It was found that quinacridone nanocrystal in different crystal form could be obtained by changing experimental conditions in HTPL method.
THE ELECTROCHEMICAL STUDIES ON A SELF-ASSEMBLED VIOLOGEN MONOLAYER USING QUARTZ CRYSTAL MICROBALANCE
Authors: OCK J. Y. , SHIN H. K. , KWON Y. S. , SONG S. H. , CHANG S. M. , QIAN D. J. , MIYAKE J.
Published: September 2003

The electrochemical behavior of viologen self-assembled monolayer has been investigated with QCM, which has been known as ng order mass detector. The self-assembly process of viologen was monitored using resonant frequency (ΔF) and resonant resistance (R). The QCM measurements indicated a mass adsorption for viologen assembling on the gold surface with a frequency change of about 300, 135 Hz and its surface coverage (Γ) was calculated to be 5.02 × 10-9 and 1.64 × 10-9 mol/cm2. A reversible redox process was also observed and analyzed with an ionic interaction at the viologen/solution interface using ΔF.
CONTROLLED AGGREGATION OF AZOBENZENE BASED ON DNA-MIMETICS AT THE AIR–WATER INTERFACE
Authors: IJIRO KUNIHARU , MATSUMOTO JIN , MORISUE MITSUHIKO , SHIMOMURA MASATSUGU
Published: September 2003

Monolayers of thymine amphiphile containing azobenzene chromophore (Azo-Thy) were prepared on various aqueous oligonucleotide ( dA 30, d(GA) 15, d(GGA) 10) subphases. Pressure–area isotherms and reflection absorption spectra of the monolayers on dA 30 or d(GA) 15 solution showed that the H-aggregate of the azobenzene units was formed at higher surface pressure than 25 mN/m . In contrast, the monolayer on an aqueous d(GGA) 10 solution did not form any aggregates of the azobenzene units even at high surface pressure. Base-pair formation between Azo-Thy and template d(GGA) 10 could give free volume to the azobenzene units in the monolayer to prevent the aggregation of the azobenzene units at the air–water interface.
TWO-DIMENSIONAL PATTERNED NANOCRYSTALLINE Si ARRAY PREPARED BY LASER INTERFERENCE CRYSTALLIZATION OF ULTRA-THIN AMORPHOUS Si:H SINGLE-LAYER
Authors: HUANG XINFAN , WANG XIAOWEI , QIAO FENG , ZHU LEYI , LI WEI , LI XUEFEI , CHEN KUNJI , KANG LIN
Published: September 2003

We employ the method of phase-modulated KrF excimer pulsed laser interference crystallization to fabricate nanometer-sized crystalline silicon with two-dimensional patterned distribution within the ultra-thin amouphous Si:H single-layer. The local phase transition occurs in ultra-thin a-Si:H film after laser interference crystallization under proper energy density. The results of atomic force microscopy, Raman scattering spectroscopy, cross-section transmission electron microscopy and scanning electron microscopy demonstrate that Si nanocrystallites are formed within the initial a-Si:H single-layer, selectively located in the discal regions with the diameter of 250 nm and patterned with the same 2D periodicity of 2.0 μm as the phase-shifting grating. The results demonstrate that the present method can be used to fabricate patterned nc-Si films for device applications.
MICRO-PHASE SEPARATION IN BINARY MIXED LANGMUIR MONOLAYERS: CORRELATION BETWEEN MOLAR FRACTION AND AREA FRACTION
Authors: SHIRAKU TATSUYA , IIMURA KEN-ICHI , KATO TEIJI
Published: September 2003

Correlation between molar fraction and area fraction in micro-phase separated structures formed in binary mixed Langmuir monolayers of arachidic acid (C20) and a perfluoropolyether amphiphile (PFPE) has been examined. On the water surface, C20 and PFPE separate into fully condensed micro-domains and a largely expanded phase, respectively. The area fraction of the condensed phase domains is estimated by two different ways: one is by analyzing atomic force microscope (AFM) images and the other is calculated from π–A isotherm data assuming complete immiscibility of the film components in the monolayers. Two area fractions are in agreement with each other, and increase exponentially with increase in molar fraction. Our results ensure the complete phase separation of the two film components on the water surface, the monolayer transfer without any structural changes, and the fruitfulness of digital image analysis for the evaluation of two-dimensional organized structures.
PRESSURE EFFECT ON CONDUCTIVITY IN Au(dmit)2 LANGMUIR–BLODGETT FILMS
Authors: MIURA YASUHIRO F. , MORITA SHIN-ICHI , SAITO SHIN-HACHIRO , SUGI MICHIO , HEDO MASATO , UWATOKO YOSHIYA
Published: September 2003

The resistance of the Langmuir–Blodgett films of ditetradecyldimethylammonium- Au(dmit) 2( 2C 14- Au(dmit) 2) salt has been measured under hydrostatic pressure up to 0.7 GPa. The room-temperature resistance decreases with increasing pressure, reaching a 0.6-times smaller value compared to that at ambient pressure. The film under the pressure shows a clear resistance decrease below 1.4 K on cooling, while that under ambient pressure shows a blunt decrease below 0.85 K and it turns to increase below 0.65 K. These results suggest the existence of the pressure-induced superconducting phase together with the earlier results of the ac magnetic susceptibility measurement.
SYNTHESIS OF NOVEL NANOMETER SIZE RUTHENIUM COMPLEXES FOR SINGLE ELECTRON CHARGING DEVICES AND THEIR ELECTROCHEMICAL PROPERTIES
Authors: ENDO HIROAKI , OGAWA TAKUJI
Published: September 2003

With the aim of studying single charging phenomena of individual molecules that have clear redox states, a series of ruthenium complexes surrounded by dendrimers were prepared. The structure and electronic characteristics of them were studied by 1 H NMR, MALDI TOF-MS, UV-vis absorption spectra and electrochemical methods. The electrochemical results revealed that the clear redox states were retained even with the surrounding dendrimers, and the molecules can be good candidates for nanometer size charging pools.
NANOSURFACE MODIFICATION USING REACTIVE LANGMUIR–BLODGETT FILMS
Authors: KADO Y. , AOKI A. , MIYASHITA T.
Published: September 2003

We describe a simple and effective approach to the introduction of a functional group into polymer nanofilms on the solid surface using reactive Langmuir–Blodgett films. N-Dodecylacrylamide copolymers containing a terminal amino group in the side chains as a reactive moiety form a stable monolayer on a water surface, and the monolayer was transferred onto a solid support with a transfer ratio of unity. The LB films were characterized by various spectroscopic methods. The reactivity of the terminal amino group incorporated in the LB films was investigated in detail using fluorescein isothiocyanate (FITC) as a fluorescent probe. The chemical reaction between the amino group in the LB films and FITC in the bulk solution was completed within approximately 30 min and the chemical bond formation was confirmed by FT-IR spectroscopy. Furthermore, the ability as a pH sensor was observed with fluorescent microscopy.
PHOTOBRIGHTENING AND PHOTODARKENING IN CdSe NANOCRYSTAL/POLYMER THIN FILMS
Authors: ASAMI HARUMI , KAMIYA ITARU , HARA MASAHIKO
Published: September 2003

The change in the photoluminescence intensity of CdSe nanocrystal/polymer thin films with duration of illumination is investigated. The choice of polymer has an influence on photobrightening and photodarkening. In particular, photodarkening in CdSe nanocrystal/poly(vinyl carbazole) thin film occurs immediately upon illumination, in contrast to the slow changes observed with polystyrene and poly(2-vinylpridine). We discuss the mechanisms of this phenomenon in comparison with interaction between surface of CdSe nanocrystals and polymer side chain.
PRECISE ANALYSIS OF OPTICALLY TRAPPED PARTICLE POSITION AND INTERACTION FORCES IN THE VICINITY OF AN INTERFACE
Authors: HOTTA JUN-ICHI , TAKASAKI HIDEHISA , FUJIWARA HIDEKI , SASAKI KEIJI
Published: September 2003

We report precise analysis of particle position while optically manipulating a particle in solution. Three-dimensional position sensing system, which we developed for measuring femto-Newton force upon a single particle, was used to detect particle position in nanometer resolution. A laser trapping system and a total internal reflection microscope are combined. During manipulation of a microparticle in the vicinity of an interface, the position of the particle behaves as stepwise transition. The spacing of the stable position is coincident with the half wavelength of the trapping laser beam, so that we conclude the surface reflection from the interface causes the stepwise transition. The force measurement is based on a thermodynamic analysis of Brownian motion, and this system can be applied to measure the force onto a single nanoparticle.
RESONANT LIGHT TRANSMISSION IN METALLIC PHOTONIC CRYSTAL SLABS
Authors: LUO XIANGANG , ISHIHARA TERUYA
Published: September 2003

Light transmission through an opaque nanoscale metallic photonic crystal slabs (MPCS) are investigated. The experimental results show that it is possible to get the extraordinary transmission in visible region even without the presence of holes, which is different from the perforated nanoholes or nanoslits in metallic system. The observed phenomenon can be understood in terms of surface plasmon-enhanced resonant emission of light through a metal structure with a nanoscale corrugation rather than light penetration through tiny holes. It is the periodicity of the interface corrugation that is important for the plasmon as a radiative channel rather than loss. The study suggests that a wide range of photonic applications is possible for such system.
DEVELOPMENT OF AN EVANESCENT FIELD SYSTEM FOR REAL-TIME DETECTION OF DNA HYBRIDIZATION
Authors: KIM DO-KYUN , KWON YOUNG-SOO , TAMIYA EIICHI
Published: September 2003

In this research, we report the characterization of the probe and target oligonucleotide hybridization reaction using the evanescent field microscopy. For detection of DNA hybridization assay, a high-density array of sensor probes were prepared by randomly distributing a mixture of particles immobilized with oligonucleotides for DNA chip applications. With the evanescent field excitation and real-time detection method, we suggest that a very sharp discrimination of bulk fluorescence against surface excitation in combination with high excitation intensities can be achieved.
MOLECULAR RECOGNITION OF NUCLEOBASES ATTACHED TO SELF-ASSEMBLED MONOLAYERS DETECTED BY CHEMICAL FORCE MICROSCOPY AND QUARTZ CRYSTAL MICROBALANCE
Authors: SUNAMI HIROSHI , IJIRO KUNIHARU , SHIMOMURA MASATSUGU
Published: September 2003

In order to develop a new DNA sequencing method by using chemical force microscopy (CFM), we have investigated the interaction of the hydrogen bonding between surfaces of nucleobase self-assembled monolayers (SAMs) and AFM-tips modified with the nucleobases. The two different adhesion forces, the jump-in force and pull-off force, between the AFM-tip modified with cytosine-SAM and the surfaces of four kinds of nucleobase SAMs were measured in water (20°C) by CFM. The adsorption of poly (C) onto a nucleobase-SAM on a gold electrode of quartz crystal microbalance (QCM) was measured as resonance frequency changes. The relative relation among four bases showed similar tendency in the adhesion force measured by the cytosine AFM-tip and in the adsorption amount of poly (C) on the QCM electrode as well as in the theoretically calculated interaction energies between two nucleobases.
FABRICATION OF ORGANIC/INORGANIC HYBRID MESO-STRUCTURES BY SELF-ORGANIZATION
Authors: YABU HIROSHI , SHIMOMURA MASATSUGU
Published: September 2003

The honeycomb patterned titania films with submicron pores were prepared by a sol–gel reaction. Self-organized 2D arrays of water droplets were formed on surfaces of reaction solution as a template. Polystyrene particles were embedded into the micropores of the honeycomb films by casting dispersion of the particles. The arrangement of aggregated particles was controlled by changing pore sizes.
CIRCULAR ARRANGEMENT OF AZOBENZENE CHROMOPHORES IN THE NUCLEOAMPHIPHILE MONOLAYER BY BASE-PAIRING WITH CYCLIC DNA
Authors: NISHIDA JIN , MATSUMOTO JIN , MORISUE MITSUHIKO , IJIRO KUNIHARU , SHIMOMURA MASATSUGU
Published: September 2003

In order to construct chromophores arrays that precisely controlled their arrangement, monolayers of an azobenzene bearing nucleoamphiphile were prepared on various oligoDNA solutions. Monolayers of the amphiphilic adenine derivative bearing an azobenzene moiety ( C 12 AzoC 5 Ade ) were prepared on thymidylic acid tetramer (dT4) and octamer (dT8) solutions, and UV-vis reflection absorption spectra of the monolayers were measured to investigate aggregation structures of the azobenzene. The absorption maximum of the monolayer was blue-shifted on the dT4 solution and red-shifted on the dT8 solution. It shows that azobenzene groups in the monolayer have parallel orientation (H aggregate) on the dT4 solution. Though, azobenzene groups have head-to-tail orientation (J aggregates) on the dT8 solution. When monolayers of C 12 AzoC 5 Ade were prepared on the synthesized cyclic oligonucleotides, the absorption spectra were totally different from those of the corresponding linear oligonucleotides.
DISEASED RED BLOOD CELLS STUDIED BY ATOMIC FORCE MICROSCOPY
Authors: CHEN YONG , CAI JIYE , ZHAO JINGXIAN
Published: September 2003

In recent years, many mammalian cells, especially erythrocytes because of simpleness of their membrane surfaces, were widely studied by atomic force microscopy. In our study, diseased erythrocytes were taken from patients of lung cancer, myelodisplastic syndrome (MDS), and so on. We obtained many clear topographical images of numerous erythrocytes, single erythrocyte, and ultramicrostructure of erythrocyte membrane surfaces from normal persons and patients. By studying the red cells of lung cancer patients, we found that many erythrocytes of lung cancer patient have changed into echinocytes. One erythrocyte has 10–20 short projections, most of which, with a mean width of 589.0 nm and a length of 646.7 nm, are on the edge of cell. The projections in the center of echinocytes are lodged and embedded, but in conventional model of echinocytes, the projections in the center stretch outside cell membrane, so a novel model of erythrocytes was designed in our paper. After observation of microstructure of MDS patient's erythrocyte membrane surface, we found that many apertures with different diameters of tens to hundreds nanometers appeared on the surface of cell membrane. It can be concluded that AFM may be widely applied in clinic pathological inspection.
PREPARATION OF THE HONEYCOMB PATTERNED POROUS FILM OF BIODEGRADABLE POLYMER FOR TISSUE ENGINEERING SCAFFOLDS
Authors: SATO KATSUHISA , HASEBE KIYOSHI , TANAKA MASARU , TAKEBAYASHI MASAFUMI , NISHIKAWA KAZUTAKA , SHIMOMURA MASATSUGU , KAWAI TOMOAKI , MATSUSHITA MICHIAKI , TODO SATORU
Published: September 2003

Fabrication and surface modification of a cell scaffold are very important in tissue engineering. In this study, the effects of pore size and surface wettability on hepatocyte adhesion and morphology was studied, using the porous poly-ε-caprolactone (PCL) film prepared by a simple casting technique. The degree of spreading of hepatocyte was enhanced with the decrease of the pore size (~10 μm). Hepatocyte motility and spreading were restricted on the patterned film having cellular-sized pores (ca. 20 μm). Partial hydrolysis of the film surface enhanced the migration and spheroid formation of the cultured hepatocyte.
STRETCHING OF SINGLE DNA MOLECULES BY LANGMUIR–BLODGETT METHOD
Authors: MATSUO YASUTAKA , IJIRO KUNIHARU , SHIMOMURA MASATSUGU
Published: September 2003

We propose a new method that double-stranded DNA molecules can be stretched and immobilized on the clean glass substrate by using a lipid monolayer at the air–water interface. This method is based on the substrate lifting of Langmuir–Blodgett method. We observed fluorescence images of polyion complex films with a scanning near-field optical microscope (SNOM). As a result, straight fluorescent lines aligned parallel to the lifting direction were observed and it was considered that isolated single DNA molecules were extended to align on the substrate. This method is applied to various DNA molecules.
PREPARATION AND CHARACTERISTICS OF SANDWICHED POLYMER/MAGNETIC PARTICLES/POLYMER MAGNETIC NANOMICROSPHERES
Authors: HONG XIA , ZHANG XINTONG , CHEN XIN , XU LI , LIU YANMEI , LIU FENGQI , BAI YUBAI
Published: September 2003

A template polymerization approach is reported to prepare uniform functional sandwiched magnetic composite nanomicrospheres with polymer core, magnetic Fe3O4mezzanine and multicomponent polymer shell. The fine superparamagnetic properties, thermostability and stability in a wide pH range of aqueous solution made the composite mirospheres had the potential applications in biology and medicine.
ELECTRIC CONDUCTIVITY OF NUCLEIC ACID POLYMER MONOLAYER
Authors: HASHIMOTO YUICHI , IJIRO KUNIHARU , SAWADAISHI TETSURO , SHIMOMURA MASATSUGU
Published: September 2003

We investigated electric conductivities of poly nucleic acid-amphiphile polyion complex monolayers. The polyion complex monolayers were prepared by spreading of dialkylammonium salt on aqueous solutions of various poly nucleic acids. The complex monolayers were compressed at the air–water interface and transferred on comb-shaped Au-electrode substrates by vertical lifting method. I–T plots of the complex monolayers, which were measured under applying direct voltage, suggested that the complex monolayers were dielectric substances. The I–V plots indicated that the conductivity of the monolayer depended on the species of poly nucleic acids. Based on the ac impedance analysis of those monolayers, the bulk resistance of those monolayers was estimated from the complex impedance plane plots.
THEORETICAL STUDY OF EXCITON–EXCITON CORRELATION EFFECT ON EXCITON MIGRATION IN MOLECULAR AGGREGATE
Authors: TAKAHATA MASAHIRO , NAKANO MASAYOSHI , YAMADA SATORU , YAMAGUCHI KIZASHI
Published: September 2003

Two-exciton migration dynamics of a molecular aggregate is performed using the density matrix approach. Exciton–exciton correlation is shown to cause an oscillatory behavior in the one-exciton population dynamics. Such a feature is found to be well explained by the bypass transition from the ground to a one-exciton forbidden state via a two-exciton state.
MICROSTRUCTURE AND RESISTIVITY OF CARBON NANOTUBE AND NANOFIBER/EPOXY MATRIX NANOCOMPOSITE
Authors: DU JIN-HONG , YING ZHE , BAI SHUO , LI FENG , SUN CHAO , CHENG HUI-MING
Published: September 2003

Single-walled carbon nanotubes (SWNTs), multiwalled carbon nanotubes (MWNTs) and vapor-grown carbon nanofibers (VGCNFs)/epoxy matrix nanocomposites were prepared, respectively. The microstructure of the nanocomposites was observed by SEM and the resistivities of the nanocomposites with different concentration of CNTs/VGCNFs were measured. Based on the experimental results, the dispersion of SWNTs and MWNTs were relatively poor but that of VGCNFs is uniform within the matrix. The resistivitiy of pure epoxy is about 1010.5Ω · cm and several orders of magnitude higher than those of SWNT, MWNT and VGCNF/epoxy nanocomposites. The resistivities of the nanocomposites drop with the increase of the CNTs/VGCNFs content in the matrix and the resistivity of VGCNFs/epoxy nanocomposites was much lower than that of CNT/epoxy nanocomposites.
REAL-TIME VISUALIZATION OF MORPHOLOGICAL EVOLUTION OF N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine THIN FILMS: VARIABLE TEMPERATURE ATOMIC FORCE MICROSCOPY STUDY
Authors: XU M. S. , XU J. B. , AN J.
Published: September 2003

Variable temperature tapping mode atomic force microscopy is exploited to in situ visualize the morphological evolution of N, N'-di(naphthalene-1-yl)-N, N'-diphthalbenzidine (NPB) thin film. The apparent glass transition of the NPB thin film initially occurred at 60°C, proceeded until 95°C, and crystallization from the glassy state quickly appeared at 135°C. The NPB thin film gradually melted and disappeared when the temperature was above 175°C, revealing the underlying layer. These observations are technically helpful and significant to gauge the temperature dependent lifetime and luminance of organic light-emitting diodes.
NANOSCALE FRICTION AND RELATED TRIBOLOGICAL PHENOMENA AT SOLID INTERFACES
Authors: KAWAGUCHI TAKAAKI , MATSUKAWA HIROSHI
Published: September 2003

Nanoscale friction and related tribological phenomena are studied by a numerical simulation. It is found that the kinetic friction is caused by some resonating phonon excitations. The contribution from the surfaces and lubricant to the kinetic friction is clarified.
USING EMISSION QUENCHING TO STUDY THE INTERACTION BETWEEN ZnO NANOCRYSTALS AND ORGANIC LIGANDS
Authors: LI JUN , ZHAO KUI , JIA RUOKUN , LIU YANMEI , BAI YUBAI , LI TIEJIN
Published: September 2003

Colloidal ZnO nanocrystals with strong green luminescence were prepared. When ZnO nanocrystals were modified with different organic ligands, the emission quenching was measured and used to study the interaction between ZnO nanocrystal and organic ligands. Efficiency of emission quenching relates to the chemical structures of the ligands, and metal-thiolate bond was formed between nanocrystals and thiol ligands. The relative strength of the binding and the surface concentration of the adsorbed species could be determined using this method.
Intracoronary β2 receptor activation induces dynamic local t-PA release in the pig
Authors: Jern Christina , Seeman-Lodding Helene , Johansson Göran , Häggmark Sören , Broomé Michael , Biber Björn , Österlund Barbro
Published: September 2003

To investigate β2-adrenergic agonist-mediated effects on coronary fluxes of local fibrinolytic factors, healthy anaesthetised and instrumented pigs (n=10) were studied during infusion of isoprenaline (IPR) into the left main coronary artery. Coronary net fluxes of total t-PA antigen, active t-PA and total PAI-1 antigen were determined at baseline and at 3, 5, 7 and 10 minutes of IPR infusion. During IPR, net release of total t-PA increased in a biphasic pattern with transiently high levels at 3 (+440 %) and 7 minutes (+620%) and returned towards baseline at 10 minutes. Net coronary release of active t-PA increased with maximum levels at 3 minutes (+50%). Baseline coronary net flux of total PAI –1 showed a decrease which was most pronounced at 10 minutes. To conclude, a fast β2agonist-mediated local release of t-PA into the coronary vasculature was demonstrated. For total t-PA, this response was characterised by a biphasic release profile.
Anti-oxidant ebselen delays microvascular thrombus formation in the rat cremaster muscle by inhibiting platelet P-selectin expression
Authors: Lindenblatt Nicole , Schareck Wolfgang , Belusa Lorenz , Nickels Ruth , Menger Michael , Vollmar Brigitte
Published: September 2003

Ebselen, a seleno-organic compound showing glutathione peroxidase-like activity, has potent anti-inflammatory and anti-oxidant effects. Since selenium deficiency is thought to be associated with an increased incidence of vascular thrombosis, we studied the effect of ebselen on blood cell aggregate formation and vessel occlusion in vivo. In individual microvessels of rat cremaster muscle preparations, photochemically induced thrombus formation was analyzed in detail using intravital fluorescence microscopy. In ebselen-pretreated animals (30mg/kg ip), venular thrombus formation was significantly delayed (50% vessel occlusion: 535±34s; initial stasis: 872±82s; complete occlusion: 908±87s) as compared to vehicle-treated controls (416±42; 612±49; 647±51). Moreover, ebselen significantly prolonged the kinetics of arteriolar thrombus formation and even completely prevented blood cell aggregate and thrombus formation in 88.9% of all arterioles studied (p<0.05 vs controls:37.5%). Anti-thrombotic properties of ebselen could also be observed in a model of ferric chloride-induced microvascular thrombosis, with a low dose (5mg/kg ip) being as effective as a high dose pretreatment (30mg/kg ip). As assessed by flow cytometry of platelet P-selectin immunfluorescence, whole blood isolated from ebselen-treated animals revealed a significantly lower fraction of P-selectin expressing platelets when compared with that of DMSO-treated controls. In addition, oxidant stress-induced upregulation of P-selectin on isolated platelets was found dose-dependently inhibited by increasing concentrations of ebselen (10-100µM). Moreover, ebselen dose-dependently inhibited H2O2-induced platelet-leukocyte aggregate formation in whole blood in vitro, suggesting that the anti-thrombotic effect of ebselen is achieved by attenuation of P-selectin dependent platelet-leukocyte aggregation. Thus, ebselen represents preventive and therapeutic value for disorders with increased risk for oxidant stress-associated thrombotic events.
Soluble CD146, a novel endothelial marker, is increased in physiopathological settings linked to endothelial junctional alteration
Authors: Moal Valérie , Anfosso Francine , Daniel Laurent , Brunet Philippe , Sampol José , George Françoise , Bardin Nathalie
Published: September 2003

CD146, a novel cell adhesion molecule localized at the endothelial junction, is involved in the control of cell-cell cohesion. It is found as a soluble form in conditioned medium of cultured endothelial cells. We developed an ELISA and report for the first time the presence of a soluble form of CD146 (sCD146) in the plasma of healthy subjects. Mean sCD146 values (260 ± 60 ng/ml) were higher in subjects over 50 years and in men. We therefore investigated sCD146 values in patients with chronic renal failure (CRF), a clinical setting associated with junctional alterations. A significant increase in sCD146 was found in patients with CRF matched with controls (457 ± 181 ng/ml versus 288 ± 82 ng/ml respectively, p<0.0001). This increase was corroborated by increased endothelial expression of CD146 on kidney biopsies from patients with CRF. In contrast, in patients with CRF no modulation was observed for the soluble and cell-associated form of CD31, another junctional molecule. Together these data indicate that sCD146 circulates in the plasma of healthy subjects. Modifications of its basal levels could reflect alterations of junctional functions such as vascular permeability.
Thrombophilia does not increase risk for neonatal complications in preterm infants
Authors: Kenet Gili , Maayan-Metzger Ayala , Rosenberg Nurit , Sela Ben-Ami , Mazkereth Ram , Ifrah Aviyah , Kuint Jacob
Published: September 2003

The association between thrombophilia and neonatal complications was evaluated in a single-center prospective study. Prevalence of genetic prothrombotic markers (FVL, MTHFR, FIIG20210A) and levels of plasma homocysteine were assayed in 166 premature (mean gestational age: 30.9±2.3 weeks) and low birth weight (mean weight: 1327±319 grams) infants. The incidence of any neonatal complications was compared in infants with and without thrombophilia. A total of 38 infants were defined as “thrombophilic” due to heterozygous FVL (n=4) and/or FIIG20210A (n=8, including one case of combination with FVL) or homozygous 677T MTHFR (n=22) or homo-cysteine plasma levels above 15µmole/liter. Neonatal complications included: small for gestational age (28.8%), respiratory distress syndrome (51.8%), broncho-pulmonary dysplasia (10.2%), patent ductus arteriosus (12.7%), intraventricular hemorrhage (17%), periventricular leucomalacia (8.4%), retinopathy of prematurity (15.1%) and necrotizing enterocolitis in 1.2% of infants. No thrombosis was documented. The prevalence of perinatal complications and the severity of diseases were similar among infants with or without thrombophilia (p=0.564). Our data suggest that preterm infants with thrombophilia are not at increased risk for developing neonatal complications.
Paris-Trousseau syndrome : clinical, hematological, molecular data of ten new cases
Authors: Favier Remi , Jondeau Katayoun , Boutard Patrice , Grossfeld Paul , Reinert Philippe , Jones Christopher , Bertoni Francesco , Cramer Elisabeth
Published: September 2003

Paris-Trousseau syndrome (PTS) is an inherited disorder char-acterized by mild hemorragic tendency associated with 11q chromosome deletion. Here we report ten new patients (5 boys,5 girls) with complete clinical history, biological data, ultra-structural and molecular investigations. Thrombocytopenia is chronic in all the patients except two boys in whom it disappeared during the two first years of life. On Romanovsky stained peripheral blood smears, abnormal platelets with giant granules were detected in all the children and confirmed by electron microscopy (EM). On bone marrow smears, dysmega-karyopoiesis with many micromegakaryocytes was constantly observed. Abnormal alpha-granules were virtually absent from bone marrow and cultured megakaryocytes, while EM detected numerous images of granule fusion within blood platelets. Molecular analyses evidenced that the fli-1 gene is deleted in all the patients except one confirming the crucial role of the transcription factor FLI-1 in megakaryopoiesis. In summary, this study documents ten new cases of PTS with characteristic alpha-granule abnormalities, and shows the putative pathogenic role of fli-1 gene in the pathophysiology of this syndrome.
Aminopeptidase inhibitor bestatin stimulates microvascular endothelial cell invasion in a fibrin matrix
Authors: Hensbergen Yvette , Peters Erna , Rana Sareena , Elderkamp Yvonne , van Hinsbergh Victor , Koolwijk Pieter , Broxterman Henk
Published: September 2003

The aminopeptidase inhibitor bestatin has been shown to have anti-angiogenic effects in a number of model systems. These effects are thought to result from inhibition of CD13 activity. Because tumor angiogenesis can evolve in a fibrin-rich stroma matrix we have studied for the first time the effects of bestatin on microvascular endothelial capillary-like tube formation in a fibrin matrix. Bestatin enhanced the formation of capillary-like tubes dose-dependently. Its effects were apparent at 8 µM; the increase was 3.7-fold at 125 µM; while high concentrations (>250 µM), that were shown to have anti-angiogenic effects in other systems, caused extensive matrix degradation. Specific CD13-blocking antibodies WM15 and MY-7, and the aminopeptidase inhibitors amastatin and actinonin also enhanced capillary-like tube formation (maximally 1.5-fold), but these effects did not reach statistical significance. The effect of bestatin was not due to a change in uPAR availability because the relative involvement of the u-PA/u-PAR activity was not altered by bestatin. In view of the present findings we hypothesize that aminopeptidases other than CD13 predominantly contribute to the observed pro-angiogenic effect of bestatin in a fibrin matrix. The identification of this novel effect of bestatin is important in the light of the proposed use of bestatin as anti-angiogenic and/or anti-tumor agent.
Ultrasound screening for distal vein thrombosis is not beneficial after major orthopedic surgery.
Authors: Michler Ronny , Klein Martin , Faulmann Grit , Weber Christian , Schellong Sebastian , Schmidt Benjamin
Published: September 2003

Ultrasound screening for deep vein thrombosis (DVT) after orthopedic surgery revealed thrombosis in up to 30% of patients, but the clinical impact of screening for distal thrombosis has not been established.

Three hundred and forty six patients after hip or knee replacement and postoperative standard prophylaxis of 10 days low molecular weight heparin (LMWH) were randomized to receive either prolonged prophylaxis with LMWH or postoperative ultrasound screening for proximal and distal thrombosis. All thrombosis found in screening was treated. Patients with a negative screening test did not receive any heparin after day 10. The cumulative rate of proximal thrombosis and symptomatic pulmonary embolism until day 35 postoperatively was determined.

In 174 screening patients, ultrasound found 55 cases of distal (31.6%) and 9 cases of proximal (5.1%) in-hospital thrombosis. In 108 screening patients without thrombosis at discharge 7 new distal (6.5%) and 6 new proximal (5.6%) thrombotic events occurred by day 35. In 163 patients with prolonged prophylaxis, 33 cases of distal (20.2%) and 7 cases of proximal (4,3%) thrombotic events occurred by day 35. The cumulative rate of proximal events was 8,7% in the screening group and 4.3% in the prophylaxis group (p=0.12).

In conclusion, ultrasound screening for thrombosis does not reduce the rate of proximal thrombosis and symptomatic pulmonary embolism 35 days after hip or knee replacement surgery.
A mutation in the integrin αIIb subunit that selectively inhibits αIIbβ3 receptor function
Authors: Perkins Kim , Loftus Joseph
Published: September 2003

The αIIband αvintegrins have been shown to play a significant role in a variety of disease processes. αIIbβ3is a platelet-specific fibrinogen receptor that is critical for thrombosis and hemo-stasis. Determination of the basis of ligand recognition by αIIbβ3is essential for modulation of platelet function. To identify αIIbresidues involved in αIIbβ3ligand binding function, cells expressing a constitutively active variant of αIIbβ3were randomly mutagenized and selected for loss of αIIbβ3ligand binding function. One mutant isolated in this manner contained a single amino acid substitution at position 96 in αIIb(Ser96→Leu). Cells expressing this αIIbmutant did not bind the ligand mimetic antibody PAC1 or adhere to fibrinogen. In addition, the mutant receptor did not bind to an RGD affinity matrix. Substitution of conserved serine residues at position 1 in β strand A of all seven repeats of αIIbsimilarly inhibited ligand binding to αIIbβ3. αIIbS96 maps to the central cavity of the β–propeller fold of the αIIbsubunit immediately adjacent to a structurally important sequence at the center of the α and β subunit interface. In contrast, substitution of the analogous residues in αvor α4did not disrupt the ligand binding function of αvβ3or α4β1. These data support a potential unique structural or mechanistic role for this residue in αIIbβ3receptor function.
Role of c-kit/Kit ligand signaling in regulating vasculogenesis
Authors: Heissig Beate , Werb Zena , Rafii Shahin , Hattori Koichi
Published: September 2003

Mobilization into peripheral blood of bone marrow-derived cells including hematopoietic stem cells (HSCs) and endothelial progenitor cells (EPCs), is regulated by chemokines/cytokines. These cells can contribute to the formation of new blood vessels (vasculogenesis) under pathological conditions including atherosclerosis, wound healing and tumor growth. We will review how these cells are mobilized into circulation, and supplied to the sites, where vessel formation is needed (i.e. ischemic tissue or tumor bed).We will give evidence that matrix metalloproteinase-9 mediated Kit ligand (Stem cell factor) processing is essential for cell mobilization induced by chemo-/cyto-kines, like vascular endothelial growth factor (VEGF), Placental growth factor (PlGF), stromal cell derived factor-1 (SDF-1). These studies may provide the basis for the development of new therapeutic strategies for vascular diseases through targeting kit ligand mediated mobilization and homing of bone marrow-derived progenitor cells for cell therapy and cancer therapy.

This publication was partially financed by Serono Foundation for the Advancement of Medical Science. Financial support: This work was supported by a grant from the Japanese Society for the Promotion of Science (B.H.) and by funds from the National Institutes of Health (CA 72006 and AR46238 to ZW). Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology from February 6-9, 2003 in Geneva, Switzerland.
Regulation of endothelial cell integrin function and angiogenesis by COX-2, cAMP and Protein Kinase A
Authors: Dormond Olivier , Rüegg Curzio
Published: September 2003

Angiogenesis, the development of new blood vessels from preexisting vessels, is a key step in tumor growth, invasion and metastasis formation. Inhibition of tumor angiogenesis is considered as an attractive approach to suppress cancer progression and spreading. Adhesion receptors of the integrin family promote tumor angiogenesis by mediating cell migration, proliferation and survival of angiogenic endothelial cells. Integrins up regulated and highly expressed on neovascular endothelial cells, such as αVβ3 and α5β1, have been considered as relevant targets for anti-angiogenic therapies. Small molecular integrin antagonists or blocking antibodies suppress angiogenesis and tumor progression in many animal models, and some of them are currently being tested in cancer clinical trials as anti-angiogenic agents. COX-2 inhibitors exert anti-cancer effects, at least in part, by inhibiting tumor angiogenesis. We have recently shown that COX-2 inhibitors suppress endothelial cell migration and angiogenesis by preventing αVβ3-mediated and cAMP/PKA-dependent activation of the small GTPases Rac and Cdc42. Here we will review the evidence for the involvement of vascular integrins in mediating angiogenesis and the role of COX-2 metabolites in modulating the cAMP/Protein Kinase A pathway and αVβ3-dependent Rac activation in endothelial cells.

The pulication was partially financed by Serono Foundation for the Advancement of Medical Sience.

Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology from February 6–9, 2003 in Geneva, Switzerland.
Lymphangiogenesis and tumor metastasis
Authors: Nisato Riccardo , Tille Jean-Christophe , Pepper Michael
Published: September 2003

In several human cancers, increased expression in primary tumors of vascular endothelial growth factor-C (VEGF-C) is correlated with regional lymph node metastasis. Studies using transgenic mice overexpressing VEGF-C, or xenotransplantation of VEGF-C-expressing tumor cells into immunodeficient mice, have demonstrated a role for VEGF-C in tumor lymphangiogenesis and the subsequent formation of lymph node metastasis. However, at variance with data obtained in animal models, there is at present very little evidence for lymphangiogenesis in human tumors. Nonetheless, the striking correlation between levels of VEGF-C in primary human tumors and lymph node metastases exists, which suggests that VEGF-C may serve functions other than lymphangiogenesis. Thus, VEGF-C may activate pre-existing lymphatics which in turn become directly involved in tumor cell chemotaxis, intralymphatic intravasation and distal dissemination. A reciprocal dialogue is therefore likely to exist between tumor and lymphatic endothelial cells which results in the formation of lymph node metastases.

This publication was partially financed by Serono Foundation for the Advancement of Medical Science.

Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology from February 6-9, 2003 in Geneva, Switzerland.
Global gene expression profiles in fibroblasts from synovial, skin and lymphoid tissue reveals distinct cytokine and chemokine expression patterns
Authors: Filer Andrew , Ross Ewan , Bofill Margarita , Martin Stuart , Salmon Mike , Parsonage Greg , Falciani Francesco , Burman Angela , Buckley Christopher
Published: September 2003

We investigated the extent to which fibroblasts isolated from diverse tissues differ in their capacity to modulate inflammation by comparing the global gene expression profiles of cultured human fibroblasts from skin, acute and chronically inflamed synovium, lymph node and tonsil. The responses of these fibroblasts to TNF-α, IFN-γ and IL-4 stimulation were markedly different, as revealed by hierarchical cluster analysis and principal component analysis. In the absence of exogenous cytokine, syn-ovial and skin fibroblasts exhibited similar patterns of gene expression. However their transcriptional profiles diverged upon treatment with TNF-α.This proved to be biologically relevant, as TNF-α induced the secretion of different patterns and amounts of IL-6, IL-8 and CCL2 (MCP-1) in the two fibroblast types. Co-culture of skin or synovial fibroblasts with synovial fluid-derived mononuclear cells provided further evidence that these transcriptional differences were functionally significant in an ex vivo setting. Interestingly, the transcriptional response of skin fibroblasts to IL-4 converged with that of TNF-α-treated synovial fibroblasts, suggesting resident tissue fibroblasts and their blood-borne precursors may be imprinted by inflammatory cytokines that are characteristic of different tissues. Our data supports the concept that fibroblasts are heterogeneous, and that they contribute to the tissue-specificity of inflammatory reactions. Fibroblasts are therefore likely to play an active role in the persistence of chronic inflammatory reactions.

This publication was partially financed by Serono Foundation for the Advancement of Medical Science.

Part of this paper was originally presented at the 2nd International Workshop on New Therapeutic Targets in Vascular Biology from February 6-9, 2003 in Geneva, Switzerland.