bluuebunny/crossref_metadata_2025_split huggingface dataset:
A copolymer of poly[2,2′‐(m‐phenylene)‐5,5′‐ bibenzimidazole] and poly(2,5‐benzimidazole) for high‐temperature proton‐conducting membranes
Authors: Yang Jingshuai , He Ronghuan , Che Quantong , Gao Xiaolei , Shi Lili 
Published: August 2010

AbstractA novel copolymer of polybenzimidazoles was prepared by copolymerization of 3,3′‐diaminobenzidine tetrahydrochloride, 3,4‐diaminobenzoic acid and isophthalic acid in polyphosphoric acid at 200 °C. The polymerization could be performed within 90–110 min with the assistance of microwave irradiation. The solubility of the copolymer obtained in N,N‐dimethylacetamide (DMAc) was improved compared with those of poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] and poly(2,5‐benzimidazole). Thus copolymer membranes could be readily prepared by dissolving the copolymer powders in DMAc with refluxing under ambient pressure. The decomposition temperature of the copolymer was about 520 °C in air according to thermogravimetric analysis data. The proton conductivity and mechanical strength of the phosphoric acid‐doped copolymer membranes were investigated at elevated temperatures. A conductivity of 0.09 S cm−1 at 180 °C and a tensile stress at break of 5.9 MPa at 120 °C were achieved for the acid‐doped copolymer membranes by doping acids in a 75 wt% H3PO4 solution. Copyright © 2010 Society of Chemical Industry
ABTS•+ scavenging activity of polypyrrole, polyaniline and poly(3,4‐ethylenedioxythiophene)
Authors: Hsu Chyong Fang , Peng Hui , Basle Cédric , Travas‐Sejdic Jadranka , Kilmartin Paul A 
Published: August 2010

AbstractAlthough many methods are available for the evaluation of the antioxidant capacity of samples presented in the liquid state, typically food and beverages, to date only the 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) assay has been applied to the measurement of the antioxidant capacity of solid samples such as active packaging materials. A modified 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) assay has been successfully developed for the measurement of the antioxidant capacity of conducting polymer powders. The ABTS•+ radical scavenging activity of polypyrrole (PPy), polyaniline (PANI) and poly(3,4‐ethylenedioxythiophene) (PEDOT) powders was compared. The ranking order for greatest antioxidant capacity among the conducing polymer powders was PANI > PPy > PEDOT. The reduced forms of all the three conducting polymer samples were found to show greater radical scavenging activity than their as‐prepared partially oxidized forms. The modified ABTS assay is a simple, rapid and sensitive method for evaluating the antioxidant capacity of conducting polymer powders. The method is also suitable for composite antioxidant materials comprising a conducting polymer and a conventional packaging polymer. Copyright © 2010 Society of Chemical Industry
Molten‐salt synthesis of oxyapatite La9.33Si6O26powders as electrolytes for intermediate temperature solid oxide fuel cells
Authors: Huang Zhaoxiang , Li Buyin , Liu Jia 
Published: August 2010

AbstractLanthanum silicate oxy‐apatites are thought of as ytrria‐stabilized zirconia substitutes in intermediate temperature solid oxide fuel cells. Lanthanum silicate oxy‐apatite powders La9.33Si6O26are successfully synthesized at lower temperature by a molten‐salt method. X‐ray diffraction, scanning electron microscopy, and precision impedance analysis used to characterize the structure, appearance, and conductivity of La9.33Si6O26. The results indicate that the apatite phase has been synthesized. The synthesis method decreases the synthesis temperature by about 300 °C in comparison to the conventional solid‐state reaction route and obtains homogeneous and nanosize powders. Dense ceramics have been prepared at sintering temperatures around 1450 °C. The used of molten‐salt powders allows a decrease of the dense ceramic pellet sintering temperature of about 200 °C. The ceramic pellets sintering at 1550 °C for 4 h have a relative density of 92% and an electrical conductivity of 1.1 × 10−3 S cm−1at 700 °C, higher than the some reported for the solid‐state synthesis method and the sol–gel method.
Adsorption of cytochrome c on diamond
Authors: Hoffmann René , Kriele Armin , Kopta Susanne , Smirnov Waldemar , Yang Nianjun , Nebel Christoph E. 
Published: August 2010

AbstractThe adsorption and conformational state of the electron transfer protein cytochrome c (cyt c) on flat, boron doped polycrystalline diamond electrodes was investigated using electrochemical techniques and atomic force microscopy (AFM). An electrochemical reduction wave from the adsorbed protein was identified as oxygen reduction, which is catalysed by the deformed heme redox centre of cyt c. We show that this catalytic activity only occurs after partial denaturation of cyt c. Therefore the reduction peak was used for characterization of the conformational state of adsorbed cyt c. AFM characterizations with molecular resolution show different conformational states of cyt c on diamond surfaces ranging from native to denaturated. Both applied techniques indicate that hydrophobic hydrogenated diamond tends to denaturate cyt c upon adsorption, while wet chemically oxidized diamond surfaces can provide extensive but non‐denaturating cyt c adsorption. The conformation and orientation of cyt c on wet chemically oxidized diamond is beneficial for the electron transfer between the protein redox centre and the diamond electrode even in the presence of oxygen.
High breakdown voltage Schottky diodes synthesized on p‐type CVD diamond layer
Authors: Volpe Pierre‐Nicolas , Muret Pierre , Pernot Julien , Omnès Franck , Teraji Tokuyuki , Jomard François , Planson D. , Brosselard Pierre , Dheilly Nicolas , Vergne Bertrand , Scharnholtz Sigo 
Published: August 2010

AbstractDiamond is a very promising material for power electronics and electrical energy management devices. Several architectures have been implemented in the past for the fabrication of Schottky diodes on boron doped microwave plasma enhanced chemical vapour deposition (MPCVD) layers and on lowly and highly boron doped stacked structures. Meanwhile, the performances often suffered several limitations, mainly due to insufficient crystalline quality of the layers or a non‐optimized diamond/metal interface. In this study, we will especially show that the achievement of diamond Schottky diode with high breakdown reverse voltage and high breakdown field goes through the optimization of several factors: a net acceptor concentration below 1016 cm−3, the epilayer growth conditions, the implementation of efficient surface passivation techniques and the integrity of the metal/diamond interface. Optimizing the previous conditions enabled us to fabricate a lateral gold Schottky diodes withdrawing reverse voltages up to 7.5 kV before avalanche breakdown induced by an electric field in the range 7–9.5 MV/cm. These findings open the route for unipolar diamond devices operating in high power electronics without the use of guard rings or edge terminations contrary to other wide band gap semiconductors.
Boron doped nanocrystalline diamond temperature regulator for sensing applications
Authors: Clukers Tim , Grinsven Bart Van , Vandenryt Thijs , Janssens Stoffel D. , Wagner Patrick , De Ceuninck Ward , Thoelen Ronald , Daenen Michaël , Haenen Ken 
Published: August 2010

AbstractIn search for a better way to monitor the hybridization and denaturation of DNA onto a diamond based sensor, precise knowledge about the conditions of the immediate surroundings is very critical. One of the factors that have a great influence on the stability of the measurements is the temperature of the liquid environment in which these measurements take place. With this as a focal point, the design of a precise temperature regulator based on a boron doped diamond thin film is a key factor to achieve accurate measurements on a standalone basis. In this work temperature control is achieved making use of a thin boron doped nanocrystalline diamond (B‐NCD) film, which, in combination with a proportional‐integral‐derivative‐control (PID), is able to maintain a stable temperature with an accuracy better than 0.1 °C. By letting the B‐NCD‐layer act as a resistor together with the appropriate control it is possible to maintain a stable temperature in a range going from room temperature till 70 °C, with an accuracy exceeding a temperature variation 0.1 °C. The first prototype makes use of a reference temperature sensor, to verify the accuracy of the results.
Accuracy of quantum Monte Carlo methods for point defects in solids
Authors: Parker William D. , Wilkins John W. , Hennig Richard G. 
Published: August 2010

AbstractQuantum Monte Carlo (QMC) approaches such as the diffusion Monte Carlo (DMC) method are among the most accurate many‐body methods for extended systems. Their scaling makes them well suited for defect calculations in solids. We review the various approximations needed for DMC calculations of solids and the results of previous DMC calculations for point defects in solids. Finally, we present estimates of how approximations affect the accuracy of calculations for self‐interstitial formation energies in silicon and predict DMC values of 4.4(1), 5.1(1), and 4.7(1) eV for the X, T, and H interstitial defects, respectively, in a 16(+1)‐atom supercell.
Template‐directed synthesis of hybrid nanowires and nanorods
Authors: Yuan Jiayin , Walther Andreas , Müller Axel H. E. 
Published: August 2010

AbstractRecently, one‐dimensional (1D) nanostructures, such as wires, rods, tubes, etc., have attracted considerable attention due to their unique shape‐ and size‐dependant properties and many potential applications. Template‐directed synthesis is a powerful and widely used method to prepare 1D objects. As robust unimolecular template, cylindrical polymer brushes have been exploited for the fabrication of various hybrid nanowires and nanorods, for instance, γ‐Fe2O3, CdS, CdSe, TiO2, silica, Au, Te, etc. As a key advantage of this polymeric templating, the obtained 1D hybrid nanostructures are colloidally stable in solution, facilitating their further solution processing.magnified image
Cryo‐TEM image of organo‐silica hybrid nanowires in aqueous solution (the inset shows a cartoon of the structure).
Surface effects and nonlinear optical properties of ZnO nanowires
Authors: Voss Tobias , Richters Jan‐Peter , Dev Apurba 
Published: August 2010

AbstractThis paper discusses the surface effects and nonlinear optical properties of ZnO nanowires. First, the influence of the large surface‐to‐volume ratio of the nanowires on their photoluminescence properties is shown. The occurrence of a surface‐exciton emission line is demonstrated and its properties are studied in time‐integrated and time‐resolved photoluminescence measurements. It is further demonstrated that this band is sensitive to surface modifications of the nanowires, such as dielectric and metallic coatings. It is shown that hydrogen can passivate deep defects in ZnO nanowires thereby reducing the defect luminescence and strongly enhancing the near‐band‐edge excitonic luminescence. The photoluminescence properties of chemically synthesized ZnO nanowires are compared to those of nanowires grown by vapor‐transport techniques. The non‐linear coefficients of chemically synthesized nanowires are analyzed, and first preliminary measurements of the optical gain of a ZnO nanowire waveguide are analyzed.magnified imageZincoxide nanowires under optical excitation.
Pros and cons of green InGaN laser on c‐plane GaN
Authors: Strauß Uwe , Avramescu Adrian , Lermer Teresa , Queren Désirée , Gomez‐Iglesias Alvaro , Eichler Christoph , Müller Jens , Brüderl Georg , Lutgen Stephan 
Published: August 2010

AbstractThe challenges of green InGaN lasers are discussed concerning material quality as a function of InGaN composition, quantum well design and piezoelectrical fields. Investigations of polar quantum well designs and comparison with simulated non‐polar structures demonstrate that the quality of the indium rich layers is more important than the influence of interface charges. A high risk of dark spots at high In concentrations of 26–33% is observed. Small changes of about 2% of In significant reduce or increase the quantity and size of dark luminescence areas. Polar designs are a trade‐off between low indium concentrations of 4 nm wide quantum wells and high overlap of electrons and holes in 2 nm narrow designs. Furthermore, our single quantum wells have less non‐radiative defects than indium rich multi‐quantum well structures. Optimized active layer designs and the material qualities enable us to get green InGaN lasers on c‐plane substrates for cw operation at 515–524 nm and wall plug efficiencies of 3.9–2.3%. Slope efficiency of 0.3–0.4 W/A allows up to now highest optical output power of 50 mW.
Which electronic structure method for the study of defects: A commentary
Authors: Lambrecht Walter R. L. 
Published: August 2010

AbstractA historic perspective is provided to the choice of methodologies for point defects in semiconductors. A summary and commentary on the highlights of the CECAM workshop: “Which electronic structure method for the study of defects?” is given, attempting to provide a link between the different contributions. To this purpose different themes running through the compilation are identified and rather than discussing individual contributions one by one, the discussion is focused around these themes. The first theme is the problem of correcting for finite size effects. The second theme is the problem of the underestimate of the band gaps and how to correct for it in defect calculations. The third theme is the self‐interaction error of local density approximation (LDA) and its repercussions for polaronic defects. The fourth theme is progress in methods beyond LDA that are becoming applicable to point defects, either for ground states or excited state properties.
Anomalies of thermal expansion and change of entropy of rare‐earth diborides at the temperatures of magnetic transitions
Authors: Novikov Vladimir , Chukina Tatiana 
Published: August 2010

AbstractAn entropy method has been proposed for calculating magnetic heat capacity Cm of rare‐earth diborides on their thermal expansion data. It was found that the temperature changes of magnetic entropy ΔSm(T) calculated from calorimetric data correlate with the magnetic components of lattice parameters Δam(T) and Δcm(T) calculated from X‐ray diffraction data. Using this correlation, a formula for Cm(T) has been derived. Calculations of Cm(T) for TbB2, DyB2, HoB2, and ErB2 have been carried out. The temperature dependencies Cm(T) obtained from X‐ray diffraction data are in a good agreement with the calorimetric data.
Agarose optical fibre humidity sensor based on electromagnetic resonance in the infra‐red region
Authors: Hernaez Miguel , Zamarreño Carlos R. , Fernandez‐Valdivielso Carlos , del Villar Ignacio , Arregui Francisco J. , Matias Ignacio R. 
Published: August 2010

AbstractA new optical fibre humidity sensor based on electromagnetic resonances (EMR) is presented in this work. An ITO layer deposited onto a 200 µm core fibre has been used as EMR supporting coating. The resultant device works as a refractometer whose EMR absorption peak shifts when the refractive index of the surrounding medium varies. An agarose layer, whose refractive index changes when it is subjected to relative humidity (RH) variations, has been deposited onto the ITO layer. This way, the new device shows a good sensitivity to RH variations, with a dynamical range of 45 nm between 20 and 80% RH. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Morphology controlled hydrothermal synthesis processes and emission near 2 µm of Tm3+‐doped Lu2O3nanostructures
Authors: Cascales Concepción , Esteban‐Betegón Fátima , Zaldo Carlos 
Published: August 2010

AbstractHydrothermal syntheses at 185 °C for 24 h yield pure cubic Ia $ \bar 3 $ nanocrystalline Tm3+‐doped Lu2O3 materials, whose morphologies are controlled through the conditions of the reaction. Chloride reagents under mild conditions produce rods of ∼15 µm length x 90 nm ∅︁ size. These nanorods exhibit photoluminescence at ∼1.95 µm, and fluorescence lifetime τ = 976 µs has been measured for 3F4 in the 2% mol Tm3+‐doped Lu2O3 sample (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An antibacterial surface coating composed of PAH/SiO2 nanostructurated films by layer by layer
Authors: Urrutia Aitor , Rivero Pedro J. , Ruete Leyre , Goicoechea Javier , Fernández‐Valdivieso C. , Arregui Francisco J. , Matías Ignacio R. 
Published: August 2010

AbstractIn this work we propose a novel antibacterial coating composed of SiO2 and the polymer Poly(allylamine hydrochloride) (PAH). The coating was fabricated by the technique Layer‐by‐Layer (LbL). This technique has already been used in previous works, and it has the advantage that it allows to control the construction of nanosized and well organized multilayer films. Here, the new nanotexturized LbL SiO2 surface acts as antibacterial agent. The fabricated coatings have been tested in bacterial cultures of genus Lactobacillus to observe their antibacterial properties. It has been demonstrated these PAH/SiO2 coating films have a very good antimicrobial behaviour against this type of bacteria. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carbon nanocapsules: blocking materials inside carbon nanotubes
Authors: Tobias Gerard , Ballesteros Belén , Green Malcolm L. H. 
Published: August 2010

AbstractFilled carbon nanotubes are of increased interest due to their potential in a wide variety of applications including drug delivery systems, data storage and nano‐electronic devices. Bulk filling of carbon nanotubes always results in samples containing a large amount of unwanted material external to the SWNT walls. For the envisaged applications of filled carbon nanotubes it is necessary to remove the external materials whilst preserving the material encapsulated in the SWNTs. We have observed that this can be achieved by closing the ends of the SWNTs or by using fullerenes to “cork” open‐ended SWNTs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient physics‐based compact model for the Schottky barrier carbon nanotube FET
Authors: Najari Montassar , Frégonèse Sébastien , Maneux Cristell , Mnif Hasséne , Zimmer Thomas , Masmoudi Nouri 
Published: August 2010

AbstractThis paper presents a computationally efficient physics‐based compact model for the Schottky barrier CNTFET. This compact model captured a number of features exhibited by these transistors such as ballistic transport and channel potential variation with respect to channel charge. Also quantum capacitance is pointed out. A new analytical model of the channel charge is presented here. The compact model accuracy is verified within its range of validity. To investigate on the SB influence, two classical circuit applications are simulated; the logical inverter and the 5 stages ring oscillator (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mid‐infrared detectors based on carbon nanotube films
Authors: Maine Sylvain , Koechlin Charlie , Fleurier Romain , Haidar Riad , Bardou Nathalie , Dupuis Christophe , Attal‐Trétout Brigitte , Mérel Philippe , Deschamps Joël , Loiseau Annick , Pelouard Jean‐Luc 
Published: August 2010

AbstractIn this paper we report the fabrication and characterization of single wall carbon nanotube film based devices. Carbon nanotubes (CNT) film is deposited on a silica substrate and usual clean room processes have been used to make Pt‐electrodes on top of it and to pattern the CNT film. The obtained devices have been used to measure the evolution of the temperature coefficient of resistance (TCR) as a function of temperature. At room temperature the TCR is –0.2%K‐1 and becomes even more important as the temperature goes down. Moreover the optical response in atmospheric band II and band III have been investigated at room temperature showing a variation of the device resistance up to 0.2% for an irradiance of ∼100 mW/cm2 in the 3–5 µm range. Such results are very promising for application of CNT films in bolometers for thermal infrared detection (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic behaviour of non‐contacting Ni nanoparticles encapsulated in vertically aligned carbon nanotubes
Authors: García J. A. , Bertran E. , Elbaile L. , García‐Céspedes J. , Svalov A. 
Published: August 2010

AbstractMagnetic properties of carbon nanotubes (CNT) obtained by plasma‐enhanced chemical vapour deposition (PECVD) have been studied. The growth of these nanotubes has been activated from Ni catalyst nanoparticles. Samples consist of Ni nanoparticles encapsulated at the tip of vertically aligned multiwalled carbon nanotubes (VACNTs) forming an homogeneous and dense large area monolayer of isolated (non‐contacting) nanoparticles. The magnetic characterisation has been performed in the temperature range of 5‐300 K with magnetic fields up to 9 T. The results show that the wide size range (30‐180 nm) of the particles originates the coexistence of blocked and superparamagnetic particles and leads to the strong ferromagnetic behaviour of the whole assembly. The coercivity decreases monotonically with increasing temperature and the value for the intrinsic coercivity is 225 Oe. The encapsulation of Ni nanoparticles by VACNTs preserves them from aggregation. This makes possible to tune the coercivity by controlling size distribution of particle monolayers. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of low‐dimensional carbon nanostructures: an efficient approach based on chemical criteria
Authors: Mercuri Francesco 
Published: August 2010

AbstractRecently, the properties of nanostructured carbon materials, like carbon nanotubes (CNTs) and graphene, have been the subject of in‐depth investigations in view of their potential use in nanotechnology. Most of the interest concerning nanostructured carbon materials is related to the peculiarities of their electronic structure, which is constituted mainly by a complex network of π‐conjugated bonds. Details of the electronic structure play a crucial role in the application of such materials as nanostructured building‐blocks for molecular electronics and in functionalization processes, where the CNTs and graphenes undergo chemical reactions. However, the particular structural and electronic features of nanostructured carbon pose significant problems to computational modeling. Recent work indicated the extension of classical organic chemistry concepts to the case of low‐dimensional nanostructured carbon materials as a successful approach to obtain an accurate and consistent description of the electronic structure of the hexagonal carbon atom network. In this work we develop a novel approach to investigations on the stability and on electronic and chemical properties of nanotubes and graphenes and related compounds. Our approach is based on the definition of suitable models of the system under study starting from chemical considerations. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)