bluuebunny/crossref_metadata_2025_split huggingface dataset:
3D Composites Based on Hydroxyapatite-Chitosan-Polysiloxane as a Biomimetic Scaffold Materials
Authors: Neira-Carrillo Andrónico , Arias José Ignacio , Fernández M. Soledad , Pai Ranjith Krishna , Quilodrán C Claudia , Arias José L 
Published: April 2011

ABSTRACTThree-dimensional (3D) composites of hydroxyapatite, phosphorylated and/or nonphosphorylated chitosan and sulphonated methylsiloxane polymer (HA/P-CHI: CHI/ S-MSP) were prepared by solid-liquid phase separation and solvent sublimation method. The HA, P-CHI and S-MSP were synthesized by chemical continuous wet-calcination, phosphorylation reaction and hydrosilylation-sulphonation reactions, respectively. 3D composites were analyzed by scanning electron microscopy (SEM). Swelling ability, stability and formation of HA particles on the composites immersed in simulated body fluid (SBF) were analyzed. Osteoblasts showed high viability when cultured on composite scaffolds. 3D composites were not degraded after 8 weeks of subcutaneous implantation in rats.
Design of Functionalized Fe3O4 Nanoparticles for Elaboration of Nanostructured Films with Magnetic Properties
Authors: Daou Toufic Jean , Mammeri Fayna , Buathong Saïwan , Bras Yves Le , Ung Diane , Gallani Jean Louis , Donnio Bertrand , Guillon Daniel , Pourroy Geneviève , Begin-Colin Sylvie 
Published: April 2011

ABSTRACTThere is currently a great interest in the preparation of nanostructured magnetic films possessing well-defined structures and controlled properties. Recent progresses in colloidal nanocrystals synthesis and processing have led to new methods for producing films and superstructures made with these materials. Hybrid films have been prepared by organizing functionalized magnetite nanoparticles in large patterns using the Langmuir Blodgett technique. Magnetite nanoparticles with an average particle diameter of 39nm have been prepared and then coated with amphiphilic molecules. The resulting decorated particles, with a hydrophobic outer layer, have proven suitable for being processed by the LB technique. The microstructure and the compacity of the nanoparticle arrays appear to depend on the nature of the organic moiety used to decorate the nanoparticles (carboxylate or phosphonate end-capped stilbene derivatives).
Titanium Oxo-Clusters: Vesatile Nano-Objects for the Design of Hybrid Compounds
Authors: Rozes Laurence , Cochet Sébastien , Frot Théo , Fornasieri Giulia , Sassoye Capucine , Popall Michael , Sanchez Clément 
Published: April 2011

ABSTRACTThe description of three titanium oxo-clusters and their use as inorganic components of hybrid organic-inorganic materials are reported. The first approach consists to add titanium oxo-clusters, [Ti6O4(C6H5COO)8(OPrn)8], in an ORMOCER⊗ based hybrid medium. Nano-sized titanium oxo-clusters combined with the chemical nature of the components, allow the tuning of the optical properties, especially the refractive index. The second approach consists to associate functionalized titanium oxo-clusters to elaborate hybrid materials with perfectly defined inorganic domains. The more relevant example of titanium oxo-cluster to build hybrid networks from nano-building blocks is the oxo-cluster [Ti16O16(OEt)32]. Indeed, the nature and the number of functional groups at the surface of these metallic oxo-clusters can be tuned in order to generate cross-linking agents of organic polymers. The studies of the structure-property relationships of the resulting nanocomposites have been investigated. Finally the structure of a purely carboxylate oxo-clusters is briefly described. This new family of stable oxo-clusters opens the way for the production of original hybrid compounds.
Mimicking the Nature to Achieve Superhydrophobic Surfaces by Vapor Phase Deposition
Authors: Gupta Sushant , Chakkaravarthi Arul Arjunan , Singh Rajiv , Stevens Nate , Opalko Jeff , Singh Deepika 
Published: April 2011

AbstractA novel technique was developed to create superhydrophobic polytetrafluoroethylene (PTFE) surface using nanosecond pulse electron deposition (PED) technique. The PTFE or Teflon thin films deposited on silicon substrate showed superhydrophobicity evidenced by the contact angle of 166±2 degrees. The SEM micrographs reveal the clustered growth of the deposited film and two level sub-micron asperities which is corroborated by the AFM. FTIR and contact angle studies were conducted to study the chemical nature and the wetting properties of the films.
Hydroxyapatite Coatings Produced by Right Angle Magnetron Sputtering for Biomedical Applications
Authors: Hong Zhendong , Mello Alexandre , Yoshida Tomohiko , Luan Lan , Stern Paula H. , Rossi Alexandre , Ellis Donald E. , Ketterson John B. 
Published: April 2011

AbstractHydroxyapatite coatings have been widely recognized for their biocompatibility and utility in promoting biointegration of implants in both osseous and soft tissue. Conventional sputtering techniques have shown some advantages over the commercially available plasma spraying method; however, the as-sputtered coatings are usually non-stoichiometric and amorphous which can cause some serious problems such as poor adhesion and excessive coating dissolution rate. A versatile right-angle radio frequency magnetron sputtering (RAMS) approach has been developed to deposit HA coatings on various substrates at low power levels. Using this alternative magnetron geometry, as-sputtered HA coatings are nearly stoichiometric, highly crystalline, and strongly bound to the substrate, as evidenced by analyses using x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR). In particular, coatings deposited on oriented substrates show a polycrystalline XRD pattern but with some strongly preferred orientations, indicating that HA crystallization is sensitive to the nature of the substrate. Post deposition heat treatment under high temperature does not result in a marked improvement in the degree of crystallinity of the coatings. To study the biocompatibility of these coatings, murine osteoblast cells were seeded onto various substrates. Cell density counts using fluorescence microscopy show that the best osteoblast proliferation is achieved on an HA RAMS-coated titanium substrate. These experiments demonstrate that RAMS is a promising coating technique for biomedical applications.
Plasma Deposited Porphyrin/Phthalocyanine Films as Promising Optical Gas Sensing Materials
Authors: Maggioni Gianluigi , Tonezzer Michele , Carturan Sara , Quaranta Alberto , Severova Katerina , Della Mea Gianantonio 
Published: April 2011

Abstract5,10,15,20 meso-tetraphenyl porphyrin (H2TPP) and copper phthalocyanine (CuPc) films have been deposited by means of a recently developed plasma based technique named glow discharge induced sublimation (GDS). The two macrocycles have been deposited by vacuum evaporation (VE) and H2TPP by spin coating (SPIN) as well for comparison. The physical properties of the films have been characterized by means of scanning electron microscopy (SEM) and nitrogen physisorption measurements. SEM images and physisorption isotherms highlight both the much higher surface roughness and specific surface area of GDS samples with respect to the VE and SPIN ones. Optical sensing measurements, performed in differently concentrated ethyl alcohol atmospheres, highlight that GDS samples yield much higher response intensities than SPIN and VE films, short response times and complete recovery.
Synthesis and Characterization of Electropolymerized Porphyrin Nanofibers
Authors: Walter Michael G. , Wamser Carl C. 
Published: April 2011

AbstractElectrochemical oxidation of tetrakis-5,10,15,20-(4-aminophenyl)porphyrin (TAPP) on fluorine-doped tin oxide electrodes leads to a conductive polymeric film (poly-TAPP) with a nanostructured fibrous morphology. The nanofiber structure and growth rate are enhanced by the addition of pyridine (5 - 15%) to the dichloromethane electrochemical solution. Electropolymerization in the absence of pyridine leads to a more highly bundled poly-TAPP structure with a spectrum indicative of protonated porphyrin units. Testing of poly-TAPP electrodes in an electrochemical iodide cell and in a 1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (PCBM) integrated solid state photovoltaic cell indicates modest photoactivity.
3D Photonic Crystals as Diffractive and Energy Selective Filter for Tandem Thin Film Solar Cells
Authors: Wehrspohn Ralf B. , Bielawny Andreas , Rockstuhl Carsten , Lederer Falk 
Published: April 2011

AbstractWe suggest a photonic structure with energy selective and diffractive properties to be incorporated in thin-film tandem solar cells. Our device enhances the pathway of incident light within a amorphous silicon photovoltaic (PV) top cell in its spectral region of low optical absorption. This leads to an increase in the short-circuit current of the top cell. For a conductive inverted opal structure as intermiediate layer, we numerically determine an current increase of 1.44mA/cm2 for an a-Si:H / &#61549;c-Si thin-film tandem cell corresponding to an increase in the absolute efficiency from 11.1% to 12.4%.
Bragg Reflector Waveguide and Electro-Optic Modulator Based on Barium Titanate Epitaxial Thin Films
Authors: Liu Zhifu , Lin Pao-Tai , Wessels Bruce W. 
Published: April 2011

AbstractWe report the nanofabrication of Bragg reflector waveguide structure based on barium titanate (BTO) epitaxial thin film grown on MgO substrate and characterized its optical transmission. A low pressure (~1 Torr) nano-lithography was used for the formation of Bragg reflector waveguide structure. We demonstrate that there is sufficient refractive index contrast to form a well-defined stop band by forming gratings in a top strip layer of Si3N4 that was grown on BTO thin film. Simulation of the optical transmission and stop band of TE mode, and electro-optic (EO) modulator tunability are discussed as well. The non-linear photonic crystal waveguides are potentially suitable as tunable optical filters and ultra-wide bandwidth modulators.
Angular Dispersion of Photonic Pseudogap in Opal vs Inverse Opal
Authors: Teh Lay Kuan , Wong Chee Cheong 
Published: April 2011

AbstractWe have recently achieved a non-dispersive, low-order pseudogap in the blue region near the L-point in electrodeposited ZnO inverse opal. This behavior is a consequence of the change in the interconnecting network of interstices from a low dielectric (air) in the opal to a high dielectric one in the inverse opal. To verify this, we present the calculated photonic bands along the LW direction, which corresponds to the angular range explored experimentally by means of angle-resolved spectroscopy. We also studied the dispersion as a function of refractive index contrast (RIC). Further increase of the RIC above the threshold necessary to open up a complete photonic bandgap between the 8th and 9th bands does not have significant effects on improving the non-dispersive characteristic in the pseudogap. The results could be extended to make other inverse photonic structures of different symmetry with non-dispersive bands suitable for the study of optical processes involving low group velocity.
Organic/Inorganic Hybrid Glasses Doped with (Erbium-ions/CdSe) Nanoparticles for Laser Amplifications
Authors: Choi Kyung 
Published: April 2011

AbstractHybrid organic/inorganic silicate materials are employed to incorporate rare-earth metal ions for laser amplification applications. Performance of laser amplifiers doped with rare-earth ions significantly relies on glassy hosts. We thus designed and synthesized highly fluorinated glassy hosts doped with biphase of Er3+/CdSe nano-particles. Fluoroalkylene-bridged xerogels containing Er3+-ions show low absorptions at the 1540 nm in this study. The presence of CdSe nano-particles also significantly influences the fluorescence environment of Er3+-ions in the fluorinated glassy matrices.
Fourier Transform Infrared Absorbance and Photoluminescence Spectroscopy Studies of CdSe Colloidal Quantum Dot/Conducting Polymer Nanocomposites for Application to Infrared Photodetectors
Authors: Lantz Kevin R. , Stiff-Roberts Adrienne D. 
Published: April 2011

AbstractIn this paper we investigate the optical properties of four CdSe colloidal quantum dot/conducting polymer nanocomposites deposited on GaAs substrates using photoluminescence and Fourier transform infrared spectroscopy absorbance. The purpose of this investigation is to find an appropriate electron-conducting polymer for use in a photoconductor that utilizes intraband transitions in the conduction band to detect mid- to long-wave-infrared radiation. As a feasibility demonstration, we fabricate a two-terminal photoconductor and characterize its dark current and spectral responsivity (at 125 K), demonstrating intraband peaks at 0.465 and 0.527 eV, which correspond to 2.67 and 2.35μm.
Micromachining for Terahertz Artificial Materials
Authors: Gallant Andrew , Swift G. Peter , Dai De Chang , Kaliteevski Mikhail , Zeze Dagou A , Wood David , Petty Michael C , Brand Stuart , Abram Richard A. , Chamberlain J. Martyn 
Published: April 2011

AbstractIn this paper we report on the development of micromachined filters for operation at terahertz frequencies. SU8, a negative photodefinable epoxy, is used to define arrays of high aspect ratio rods which are subsequently sputter coated in gold to form the filter. We fabricate and test a filter with a fixed period but variable diameter along the length of the array. By moving the array in the terahertz beam we demonstrate the ability to mechanically tune specific filter characteristics from a single device.
Support Controlled Catalytic Chemical Vapor Deposition of Carbon Nanotubes
Authors: Wang Yunyu , Li Bin , Luo Zhiquan , Shi Li , Yao Zhen , Bryan Eugene N , Nemanich Robert J , Ho Paul S 
Published: April 2011

AbstractCarbon nanotubes (CNTs) have been grown by catalytical chemical vapor deposition (CCVD) with a thin iron layer as the catalyst. High surface tension metal, tantalum (Ta), and low surface tension, SiO2, have been deposited as the supporting layers before depositing the catalysts. SEM, TEM, STEM and EELS have been used to examine the morphology, structure, and chemical profile of iron nanoparticles and CNTs. The results have shown that the catalyst nanoparticle morphologies were distinctly different on two supports. In particular, Fe nanoparticles on SiO2 were found to follow a Vollmer-Weber (VW) growth mode and a Stranski-Krastanov (SK) growth mode on Ta. It was also found that CNT growth varied significantly on two supports in terms of morphology, growth rate and growth mode. Dense CNTs were grown on Ta with fast growth rates (> 1µm/min) and vertical alignment for the iron thicknesses of 1.5-9 nm. In contrast, CNTs grown on SiO2 exhibited a slow growth rate (< 100 nm/min) with all deposited iron thicknesses, indicating a severe catalyst poisoning. The results suggested that the catalyst morphology in combination with the presence of an iron wetting layer contributed to the enhanced CCVD growth of CNTs on Ta.
Growth of Boron Nanowires by Chemical Vapor Deposition
Authors: Guo Li , Singh Raj N. 
Published: April 2011

AbstractMotivated by the extensive research on carbon nanotubes (CNTs), boron and its related nano-structures have attracted increasing interests for potential applications in nanodevices and nanotechnologies due to their extraordinary properties. B-related nanostructures are successfully grown on various substrates in a CVD process. The boron nanowires have diameters around 50-200 nanometers and lengths up to a few microns. The gas chemistry is monitored by the in-situ mass-spectroscopy, which helps to identify reactive species in the process. Modified vapor-solid growths as well as VLS growth mechanisms are proposed for the growth of these nanostructures. The role of the catalysts in the synthesis is also discussed.
Composition and Strain Dependence of the Piezoelectric Coefficients in Semiconductor Alloys
Authors: Hammerschmidt T. , Migliorato M. A. , Powell D. , Cullis A. G. , Srivastava G. P. 
Published: April 2011

AbstractWe propose a tight-binding model for the polarization that considers direct and dipole contributions and employs microscopic quantities that can be calculated by first-principles methods, e.g. by employing Density Functional Theory (DFT). Applying our model to InxGa1-xAs alloys allows us to settle discrepancies between the values of e14 as obtained from experiments and from linear interpolations between the values of InAs and GaAs. Our calculated piezoelectric coefficient is in very good agreement with photo current measurements of InAs/GaAs(111) quantum well samples.
Direct Assembly of Quantum Confined Nano-Particles
Authors: Pluemel Ingo , Hitzbleck Klemens , Rangelow Ivo W. , Meijer Jan , Wiggers Hartmut 
Published: April 2011

AbstractAdvances in nanoparticle technology enable the production of new types of electronic devices, catalytic systems and complex functional surface coatings. For most of these applications, random deposition or self-assembled arrangement of the particles on surfaces are sufficient. However, an increasing number of potential applications such as single electron transistors and quantum computers require exact placement of single nanoparticles with sub-10 nm resolution and specific size. Till date, techniques that provide an exact online placement of countable and size-selected nanoparticles for functional devices have not been reported. For this purpose a cluster-jet system, based on a gas-phase nanoparticle synthesis source, connected to a focussing collimator system has been developed. The objective of this technique is to assemble countable single nanoparticles with spatial resolution of 10 nm or below onto a pre-structured substrate. In the first stage of this system, nanoparticles in the size regime between 3 and 10 nm are synthesized in a lowpressure microwave plasma reactor. This reactor has the unique advantage of generating particles with defined size distribution, structure, morphology and low degree of agglomeration due to coulomb repulsion during particle formation and growth. Separated single particles are extracted by means of a particle laden molecular beam. A mass filter consisting of a particle mass spectrometer (PMS) coupled to the reactor is used to select nanoparticles of a specific size, according to their mass, charge and kinetic energy. In order to achieve the designated lateral resolution, the particle laden beam will be collimated by electromagnetic lenses and focused onto a pierced AFM-tip. Operation of the focusing mechanism and tip preparation have been successfully performed separatly and are currently being adapted to the use in the cluster-jet system. After completion, this technique is intended to enable the assembly of nanoparticles in almost any desired two-dimensional structure onto a substrate.
Silica Nanoparticles Three Dimensional Assembly: An Integrative Chemistry Approach Toward Designing Opal-Like Silica Foams
Authors: CARN Florent , BACKOV Renal 
Published: April 2011

AbstractNovel meso-/macroporous SiO2 monoliths have been reached by applying a nanotectonic pathway within a confined geometry, i.e. a non-static air-liquid foam pattering process. Final scaffolds are a very close transcription of the tailored periodic air-liquid foam template while highly ordered close-packed silica colloids are texturing the as-synthesized foam walls. The interconnected nanoparticles and associated void space between adjacent particles allow generating intrinsic mesopores, thereby defining hierarchically organized porous scaffolds. The good control over both the air-liquid foam's water volume fraction and the bubble size allow a rational tuning of the macropore shape (diameter, Plateau border's width). At the nano-scale, heterogeneous textural character is associated with abrupt variation in the film's topology certainly governed by the complex liquid flow present within the foam film. This flow induces a surfactant concentration gradient that causes a sort of marginal regeneration on the side of the film. According to these observations, the heterogeneous character of the film surface revealed by AFM can be interpreted like a direct expression of the liquid flow within the air-liquid foam's film.
Transmission Electron Microscopy Study on the Surface Properties of CNTs and Fullerites Exposed to CF4 Plasma
Authors: Shoda Kaoru , Takeda Seiji 
Published: April 2011

AbstractVarious types of CNTs, i.e. single-wall, double-wall, triple-wall, quadruple-wall and multi-wall carbon nanotubes (CNTs), and fullerites were fluorinated in inductive coupled radio-frequency (RF) CF4 plasma at 13.56 MHz, and their structural and bonding properties were investigated by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). We have discussed the correlation between the number of graphene sheets in a CNT and the stability against the fluorination. TEM and XPS analysis clearly state that increase of the number leads to the gain of fluorinated stability. The fluorination of CNTs is initiated at outer tubes and proceeds to inner tubes with increasing RF power, but fluorination depth is limited to only surface area. The fluorination of fullerites forms amorphous layer at the surface, and increases the depth of the layer with RF power.
Modeling and Simulation of n-Type Carbon Nanotube Field Effect Transistors Using Ca as Contact Electrodes
Authors: Khan Aurangzeb , Shah A. Q.S , Gou Jihua 
Published: April 2011

AbstractIn this research work, a model has been proposed in view of the recent experimental demonstration using Calcium (Ca) as a contact metal to realize the n-type carbon nanotube field effect transistors (CNTFET). In order to fully optimize this proposed device model, effects of different parameters like the work function, oxide thickness, the oxide capacitance and the source velocity limits were studied. Among all the parameters, the work function of the contact metal plays an important role for controlling the flow of carriers through the carbon nanotube channel and to reduce the threshold voltage. A semi-classical simulation of the proposed n-type CNTFET has been performed. Results show an excellent subthreshold swing value of 62.91 mV/decade, close to the International Technology Roadmap for Semiconductor (ITRS) specifications.
Electrical and Thermal Properties of Carbon Nanotube Polymer Composite Films
Authors: Dervishi Enkeleda , Li Zhongrui , Saini Viney , Biris Alexandru R. , Lupu Dan , Trigwell Steve , Biris Alexandru Sorin 
Published: April 2011

AbstractThe electrical and thermal properties of carbon nanotubes (CNT)-polymer nanocomposite materials have been studied. The carbon nanostructures were analyzed by several analytical techniques, including Electronic Microscopy, Raman Spectroscopy, and X-Ray Photoelectron Spectroscopy. Carbon nanotubes were grown by catalytic chemical vapor deposition on metal/metal oxide catalytic systems using acetylene or other hydrocarbons. Raman Spectroscopy was used to analyze the CNT and CNT-polymer nanocomposite materials. The thermal and electrical properties of these CNT-polymer nanocomposite materials depend on the amount of CNTs in the polymer and also on the uniformity of the CNTs dispersed in the polymer. A reduction in electrical resistivity was observed, as the nanotubes' concentration in the polymeric films increased, while optical transparency remained 85 % or higher relative to acrylic films without nanotubes.