bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactive Co-Evaporation of YBCO for 2G HTS Tapes
Authors: Storer Jonathan , Hänisch Jens , Sheehan Chris , Matias Vladimir 
Published: April 2011

AbstractWe present a new reel-to-reel method for growth of high temperature super-conducting (HTS) films by reactive co-evaporation on flexible metal tapes. We have demonstrated proof of principle for this method with a small laboratory-scale setup using 8 cm long tape pieces. YBa2Cu3O7-δ is deposited on ion-beam assisted deposition textured MgO layers on top of flexible polycrystalline metal tapes. Critical current densities at 75.5 K of over 2 MA/cm2 have been achieved in HTS films with over 2 μm in thickness, yielding a self field critical current of 450 A/cm-width. A 4.5 μm thick film had a self field critical current of 590 A/cm. We discuss some practical possibilities for manufacturing of superconducting wire using this process and present new areas of research that are still needed.
Fabrication of Piezoelectric Polyvinylidene Fluoride (PVDF) Microstructures by Soft Lithography for Tissue Engineering and Cell Biology Applications
Authors: Gallego Daniel , Ferrell Nicholas J. , Hansford Derek J. 
Published: April 2011

ABSTRACTA method for the fabrication of piezoelectric polyvinylidene fluoride (PVDF) microstructures is described. Embossed and individual features with highly defined geometries at the microscale were obtained using soft lithography-based techniques. Various structure geometries were obtained, including pillars (three different aspect ratios), parallel lines, and criss-crossed lines. SEM characterization revealed uniform patterns with dimensions ranging from 2 μm ñ 15 μm. Human osteosarcoma (HOS) cell cultures were used to evaluate the cytocompatibility of the microstructures. SEM and fluorescence microscopy showed adequate cell adhesion, proliferation, and strong interaction with tips and corners of the microdiscontinuities. Microfabricated piezoelectric PVDF structures could find applications in the fabrication of mechanically active tissue engineering scaffolds, and the development of dynamic sensors at the cellular and subcellular levels.
Photoresist Free Negative and Positive Photolithographic Deposition of Zirconium Oxide Films from Photosensitive Metal Organic Compounds
Authors: Zhang Xin , Hill Ross H. 
Published: April 2011

ABSTRACTPhotoresist free photolithographic deposition of zirconium oxide from photosensitive zirconium complexes has been achieved using photochemical metal organic deposition. In this contribution, the deposition of patterned zirconium oxide is used as an example to demonstrate both negative and positive photolithographic deposition. In the prototypical deposition of zirconium oxide by photochemical metal organic deposition, a solution containing zirconium (IV) di-n-butoxide bis(2, 4-pentanedionate) was used to spin coat a silicon substrate, resulting in an amorphous film. The film was then exposed to UV light leading to the formation of zirconium oxide and other volatile products. The resultant zirconium oxide film was investigated by X-ray diffraction and Auger Electron Spectroscopy. Irradiating the precursor film through a photo mask led to a latent image which yielded either a negative or a positive pattern dependent upon developer. Subject to further photochemical or thermal treatment, a zirconium oxide pattern can be obtained. Similar results were obtained using a series of zirconium (IV) complexes. Both positive and negative patterns of zirconium oxide with 2 micron feature sizes were obtained.
Device Model for Light-Emitting Field-Effect Transistors with Organic Semiconductor Channel
Authors: Ruden P. Paul , Smith Darryl L. 
Published: April 2011

AbstractWe present a device model for light-emitting, ambipolar, organic field-effect transistors based on the gradual channel approximation. The model results are in very good agreement with recent experimental data. Trapping of injected carriers in localized states in the channel region is shown to be an important mechanism that can strongly affect the transfer characteristics and the light emission of these devices.
Role of Charge Interaction in the Behavior of Organic Thin Film Transistors
Authors: Erlen Christoph , Brunetti Francesca , Fiebig Matthias , Scarpa Giuseppe , Nickel Bert , Di Carlo Aldo , Lugli Paolo 
Published: April 2011

AbstractStrong hysteresis in the I-V characteristics of organic thin film transistors are a severe obstacle for the implementation of large circuits. It therefore is a key success factor for the optimization and widespread application of organic electronics to understand the underlying principles. We report the fabrication of two types of pentacene transistors with either polyvinyl alcohol (PVA) or SiO2 as gate dielectric. These devices respond to transient measurement sweeps with a fundamentally different I-V hysteresis. A self-contained model is presented, which associates this behavior with the influence of traps at the SiO2/pentacene interface and polarization in the PVA layer. Simulations employing the commercial drift-diffusion tool SENTAURUSTM are performed to verify our models.
Study of Oxetane Toughened Cationic UV Curable Marine Fouling Release Coating
Authors: Chen Zhigang , Wagner Rachel , Patel Sandeep , Kim Jongsoo , Stafslien Shane , Daniels Justin , Wal Lyndsi Vander , Siripirom Chavanin , Chisholm Bret 
Published: April 2011

AbstractTo develop a cationic UV curable, tough fouling-release coating for marine vessels, a difunctional oxetane monomer was used to copolymerize with the epoxy-siloxane oligomer at loading levels from 10% to 40% wt.. The resulting coatings showed enhanced solvent resistance, impact resistance and modulus, while remained hydrophobic before and after immersion in artificial sea water. In marine microorganism bioassay, these oxetane toughened coatings showed no leachate toxicity and the coating surfaces were non-toxic to biofilm growth. The fouling removal performance for these coatings was found to be microorganism dependent. Live barnacle reattachment assay showed that the toughened coatings had a removal force comparable to the reference silicone coatings Dow Corning T2 and 3140.
Electrical Transport Behavior in Phenolic Resin-based Composites Doped with Multi-walled Carbon Nanotubes
Authors: Minamisawa Renato Amaral , Chhay Bopha , ILA Daryush 
Published: April 2011

AbstractThe reported electromagnetic properties of carbon nanotubes (CNT) make them a promising material for nanoelectronic applications [1,2]. Addition of CNT has recently been shown to enhance mechanical properties of phenolic-resin polymers [3]. We are attempting to control the electrical transport behavior of phenolic-based polymers doped with CNT as a function of the different nanopowder concentration added to the polymer. In that regard, we developed a technique to obtain a material with homogenous dispersion of nanopowders, an important factor that influences the transport behavior. The chemical structure characterization was also evaluated using optical techniques.
Glassy Polymeric Carbon Resistivity as a Function of Carbon Nanotubes
Authors: ILA Daryush , Minamisawa Renato , Budak Satilmis , Zheng Bangke , Ila Daryush 
Published: April 2011

AbstractGlassy Polymeric Carbon (GPC) is a material widely used because of its high temperature properties, inertness and biocompatibility [1]. GPC samples were prepared from a phenolic resin, cured in a careful process at 100 ºC and pyrolyzed to 1000 ºC. In this work, we have introduced 3wt%, 10wt%, and 20 wt% of Carbon Nano Tubes (CNT) in the precursor resin to study the evolution of the electrical conductivities of the nanocomposite as a function of the CNT concentration.
Nanostructuring of Hybrid Silicas: New Approach to Bridged Silsesquioxanes with Purine-Pyrimidine Base Pairs as Bridging Units
Authors: Man Michel Wong Chi , Arrachart Guilhem , Carcel Carole , Moreau Joël J.E. , Bonhomme Christian , Babonneau Florence , Creff Gaëlle , Bantignies Jean-Louis , Dieudonne Philippe , Alonso Bruno 
Published: April 2011

ABSTRACTA new route to synthesize hybrid silica-based network with bridging organic units via molecular recognition is described. The hydrolysis of two monosilylated complementary base pairs, one bearing an adenine fragment and the other a thymine fragment leads to the formation of a powdered sample that has been characterized by Scanning Electron Microscopy (SEM), Powder X-ray Diffraction (PXRD) FTIR and solid state NMR (1H, 13C and 29Si). This last technique proved to be extremely powerful to directly demonstrate the occurrence of heteroassembly of the nucleobase-based silylated fragments, through the use of two-dimensional 1H double-quanta MAS-NMR that could probe spatial proximities between the thymine NH groups and the adenine NH2 groups.
Phase Separation in Alkoxy-Derived Silica System Containing Polyacrylamide
Authors: Kawamoto Kousuke , Nakanishi Kazuki , Hanada Teiichi 
Published: April 2011

ABSTRACTBy inducing phase separation parallel to the sol-gel transition of alkoxy-derived silica systems, gels having both macroporous and mesoporous structures can be obtained. Using poly(acrylamide) (PAAm) as a phase-separation inducer, macro/mesoporous silica gels were synthesized. After solvent exchange by water, the size distribution of mesopores of wet gels was evaluated by thermoporometry using a differential scanning calorimetry (DSC). Alternatively, gels were evaporation-dried after solvent exchange by ethanol or water/ethanol, followed by heat-treatment to completely remove volatile and organic components. Characterization of the dried or heat-treated samples was carried out using a scanning electron microscope (SEM) and by nitrogen adsorption measurements. Experimental results showed that the interaction between PAAm and silica is not so strong as the case of polymers having poly(oxyethylene) chains. The contribution of the secondary phase separation within the crosslinking silica-rich phase was suggested to be responsible for the mesopore formation in the PAAm-silica system.
Material Characterisation of a Novel Permeation Barrier for Flexible Organic Displays
Authors: Gartside Jonathan , Mandlik Prashant , Wagner Sigurd , Zhou Teddy , Silvernail Jeff , Hack Mike 
Published: April 2011

ABSTRACTEncapsulation for flexible organic light emitting diodes (OLEDs) is an area of active research. Multilayer barriers, with alternating organic and inorganic layers, currently offer the best resistance to oxygen and water ingression. However, the complexity of the multilayer structure makes the deposition costly and time-consuming. Here we report an effective single-compound barrier layer deposited by single-chamber plasma enhanced chemical vapour deposition (PE-CVD) from hexamethyl disiloxane (HMDSO) and oxygen source gases. The barrier layer has displayed excellent permeation resistance, with coated OLED devices surviving over 1000 hours in accelerated shelf-life tests (65°C and 85% relative humidity) in near perfect condition. Material characterisation detailed in this paper indicates that the material is an inorganic-polymer hybrid, combining the permeation resistance of an oxide with the flexibility of a polymer. The surface characteristics, chemical composition and mechanical properties of the novel barrier material are investigated with variation in PE-CVD deposition conditions.
Polymer-Silica Nanocomposite Aerogels with Enhanced Mechanical Properties Using Chemical Vapor Deposition (CVD) of Cyanoacrylates
Authors: Boday Dylan J. , Loy Douglas A. , DeFriend Kimberley A. , Wilson Kennard V. , Coder David 
Published: April 2011

ABSTRACTAerogels were structurally modified using chemical vapor deposition (CVD) of cyanoacrylate monomers to afford polycyanoacrylate-aerogel nanocomposites. Silica aerogels are low density, high surface area materials whose applications are limited by their fragility. Cyanoacrylate CVD allowed us to deposit a film of organic polymer throughout fragile porous monoliths within hours. Our experiments have shown that polymerization of the cyanoacrylate monomers was initiated by the adsorbed water on the surface of the silica permitting the nanocomposites structures to be formed with little or no sample preparation. We found that the strength of the polycyanoacrylate-aerogel nanocomposites increased thirty two-fold over the untreated aerogels with only a three-fold increase in density and an eight-fold decrease in surface area. Along with the improvement in mechanical properties, the aerogels became less hydrophilic than un-modified aerogels. Polycyanoacrylate-coated aerogels were placed directly into water and did not suffer catastrophic fragmentation as observed with un-modified silica aerogels.
Synthesis and Orientation of Poly(Dialkylstannane)s
Authors: Choffat Fabien , Fornera Sara , Smith Paul , Caseri Walter 
Published: April 2011

ABSTRACTPolystannanes, i.e. organometallic polymers of the chemical formula (SnR2)n, are relatively little explored, although they belong to the rare examples of polymers which are characterized by a backbone of metal atoms which are linked by covalent bonds. We developed a new synthetic route which yields pure linear poly(dibutylstannane) [Sn(Bu)2]n by polymerization of dibutylstannane (dibutyltin dihydride) with the catalyst [RhCl(PPh3)3]. Here, we report that the conversion and the reaction rate of dibutylstannane depends crucially on the temperature and [RhCl(PPh3)3] is also suited for the polymerization of dioctylstannane and didodecylstannane. The polymers thus obtained were characterized by 1H, 13C and 119Sn NMR spectroscopy: Orientation of all polystannanes was achieved by tensile drawing. The orientation was examined by UV-vis spectroscopy with polarized light and X-ray diffraction. Remarkably, the orientation of the backbone depended on the length of the alkyl groups.
Fabrication of Fluorescent Cellular Probes: Hybrid Dendrimer/Gold Nanoclusters
Authors: Zhong Chang , Bao Yuping , Vu Dung M. , Dyer R. Brian , Martinez Jennifer S. 
Published: April 2011

ABSTRACTFluorescent metal nanoclusters, which consist of collections of small numbers of noble metal atoms, are of great interest in photochemistry and photophysics due to their strong size-dependent emission. Historically their generation was confined to gaseous and solid phases; however, recently a unique organic/inorganic hybrid materials approach was developed that utilizes dendrimers as templates to protect nanoclusters from solution based fluorescence quenching. These hybrid dendrimer/gold nanoclusters are water-soluble and highly fluorescent. Yet there are several intrinsic deficiencies in their synthetic method: first, NaBH4, a toxic chemical, was used as reducing agent in the reaction; and second, the reaction yield was low due to the concurrent formation of large, non-emissive, gold particles. Here we report a particle-free method to produce dendrimer-encapsulated gold nanoclusters in high-yield. Proof of concept is demonstrated using OH-terminated poly(amidoamine) dendrimer and Au(PX3)3Cl (X = Ph, Me), but the approach can also be extended to the combination of other dendrimers and organic noble metal salts. Our approach yields fluorescent clusters with homogeneous size distribution. These clusters can be transferred to aqueous solution and used directly for biological applications.
Bio-Inspired Mineralization from Aqueous Solutions of Zinc Nitrate Directed by Building Blocks of DNA
Authors: Jost Micha , Gerstel Peter , Bill Joachim , Aldinger Fritz 
Published: April 2011

AbstractIn this paper, the suitability of DNA- and RNA-bases, nucleosides and nucleotides, and DNA itself as structure-directing agents for the mineralization of ZnO-based materials is discussed. Those bioorganic molecules are able to trigger the morphology of mineralization products ranging from smooth, homogenous thin films to sponge-like, sheet-like and fibrous products. Besides the investigation of morphological features by scanning electron microscopy, the structural characterization of these materials by X-ray diffraction, vibrational spectroscopy, photoluminescence spectroscopy and photoelectron spectroscopy is discussed.
A method to Generate Biomimetic Superhydrophobic Engineering Surfaces
Authors: Zhang Yilei , Sundararajan Sriram 
Published: April 2011

AbstractA versatile hybrid processing method that combines electrostatic deposition of microparticles and subsequent anisotropic plasma etching is described that can generate superhydrophobic engineering surfaces with tunable bimodal roughness and a thin hydrophobic fluorocarbon film. These surfaces exhibit contact angles with water of more than 160°.
Electrochemical Release of Immobilized IgG Protein
Authors: Mahmud Tanveer , Wlodarski Wojtek , Mitchell Arnan , Gras Sally , Trinchi Adrian , Kalantar-zadeh Kourosh 
Published: April 2011

AbstractIn this paper, we present the electrochemically programmed release of immobilized IgG protein molecules that have been attached to gold coated surfaces via a thiol-gold linkage. Fluorescence microscopy has been used to image the release of fluorescently tagged IgGs in phosphate buffered saline. In this technique, the reductive desorption of self-assembled monolayers is employed for the release of proteins, which are immobilized on the surface either by non-covalent or covalent interactions. The voltage applied for the release of proteins is in a range of -1.5V to -60V.
High Sensitivity Photonic Crystal Biosensor Incorporating Nanorod Structures for Enhanced Surface Area
Authors: Zhang Wei , Ganesh Nikhil , Block Ian D. , Cunningham Brian T. 
Published: April 2011

AbstractWe report efforts at enhancement of the surface area of a photonic crystal biosensor through incorporation of a porous titanium dioxide film into the device. The film possessing the structure of nanorods is deposited by the glancing angle deposition technique. Results for detection of polymer films, large proteins and small molecules indicate up to a four-fold enhancement of detected adsorbed mass density for high surface area sensors, compared with sensors without the high surface area coating.
ITO-Based Cathode for Application in Semitransparent Organic Photovoltaic Cells
Authors: Ng Ging-Meng , Kietzke Elizabeth Lekha , Kietzke Thomas , Tan Li-Wei , Liew Pooi-Kwan , Zhu Furong 
Published: April 2011

AbstractA high performance semitransparent cathode is one of the major impediments to the high performance semitransparent and tandem organic photovoltaic (OPV) cells. In this work, we discuss the possible designs of semitransparent cathode to improve the performance of semitransparent OPV cells. The optical properties of the poly(3-hexylthiophene) (P3HT): 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM)-based OPV cells were studied by the optical admittance analysis. The performance of the OPV cells made with an opaque Ca(10nm)/Ag(100nm) cathode and a semitransparent Ca(10nm)/Ag(10nm)/ITO cathode are discussed. The interfacial properties at the cathode/organic interface were analyzed using the time-of-flight secondary ion mass spectroscopy (TOF-SIMS). The TOF-SIMS depth profile revealed that calcium oxide formed at the Ca/organic interface in semitransparent OPV cells, which was induced by the ITO sputtering process. It shows that the presence of calcium oxide at the organic/cathode interface could be the main reason resulting in a poor fill factor of a semitransparent OPV cell (∼23%) as compared to that of a reference cell (∼43%).
Electrical and Photoelectrical Properties of Nanostructured ZnO Thin Films for Photovoltaic Applications
Authors: Antohe Stefan , Tazlaoanu Cezar , Socol Gabriel , Magherusan Larisa , Enculescu Ionut , Bazavan Dan , Mihailescu Ion , Antohe Stefan 
Published: April 2011

AbstractStructural, electrical and optical characterizations of nanostructured ZnO thin films used as photosensitized electrodes in photovoltaic cells applications are reported. Nanostructured ZnO thin films were deposited on optical glass substrates by pulsed-laser deposition (PLD), their structure and morphology being optimized for photovoltaic applications. Structural analysis of the samples by X-ray diffraction revealed that the films consist of a hexagonal-close-packed wurtzite type phase ZnO, (001) preferentially oriented in the growth direction. The ZnO films are highly transparent in visible region of solar spectrum, and exhibit electrical resistivities in the range 10-4 - 10-2Ω.m
Photonic Crystal Structures of Biologic Origin: Butterfly Wing Scales
Authors: Biró L´szló Péter , Bálint Zsolt , Kertész Krisztián , Vértesy Zofia , Márk Géza István , Tapasztó Levente , Vigneron Jean-Pol , Lousse Virginie , Biro Laszlo Peter 
Published: April 2011

AbstractPhotonic crystal type nanoarchitectures (built of chitin and air) occurring in the scales of two male butterflies, with dorsal blue and ventral green coloration were investigated by optical microscopy, SEM and TEM. Reflectance data were collected by normal incidence measurements and by integrated reflectance measurements, too. Reflectance peaks with close positions in the blue range of the spectrum were found both for the single crystalline scales and for the most disordered photonic band gap material. Polycrystalline structures with grain size on the micron scale produce matt reflectors, while moderately ordered “pepper-pot” type structures can yield surfaces with shiny aspect. It was found that the cover scales on each sides of the wing are primarily responsible for the observed colors. The character of the observed colors (shiny, or matt) correlates with the habitat of the investigated butterflies.
Chemical Tension in VLS Nanostructure Growth Process: From Nanohillocks to Nanowires
Authors: Li Na , Tan Teh Y. , Gösele Ulrich 
Published: April 2011

AbstractABSTRACTWe formulate a global equilibrium model to describe the growth of 1-d nanostructures in the VLS process by including also the chemical tension in addition to the physical tensions. The chemical tension derives from the Gibbs free energy release due to the growth of a crystal layer. The system global equilibrium is attained via the balance of the static physical tensions and the dynamic chemical tension, which allows the system to reach the minimum Gibbs free energy state. The model predicts, and provides conditions for the growth of nanowires of all sizes exceeding a lower thermodynamic limit. The model also predicts the conditions distinguishing the growth of nanaohillocks from nanowires.
Enhanced Tunneling through sub 30 Angstroms Thick Gallium Nitride Cap Layers on Silicon Carbide for Low Contact Resistance
Authors: Praharaj Choudhury Jayant 
Published: April 2011

AbstractWe present numerical calculations of tunneling through ultra thin wurtzite Gallium Nitride cap layers on p-doped wurtzite silicon carbide . We demonstrate the predominance of tunneling of the split-off holes to the total carrier flux, with the contribution of the heavy and the light holes damped by the large potential barrier. We calculate the contributions of spontaneous and piezoelectric polarizations to the tunneling profile seen by the holes. Two orders of magnitude enhancement is seen in the transmission probabilities for a 10 angstroms thick Gallium Nitride cap layer for holes very close to the valence band edge, compared to a barrier without any gallium nitride cap. The contact resistances are also calculated for the Gallium Nitride tunneling caps and more than two orders of magnitude lowering is seen with the ultra-thin caps. Larger cap widths induce hole accumulation layers, but the advantages of hole accumulation are offset by the higher effective tunneling width. Our calculations are relevant to nanostructures and nanodevices involving heterojunctions between gallium nitride and silicon carbide and provide the basis for low contact resistances with as-deposited metals. While our calculations focus on the regime of very high barriers to the metal of the order of 1.5 - 2 electron volts, where the method of ultra-thin caps is most useful, similar conclusions also hold for lower barrier heights.