bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication and Optical Characterization of Silicon Carbide Nanofibers
Authors: Khan Saima , Khan Aurangzeb , Kordesch Martin E. 
Published: April 2011

AbstractSilicon Carbide (SiC) nanofibers were synthesized from SiC powder dispersed in polyethylene oxide (PEO) solution in Chloroform using the electrospinning technique. The as-spun fibers were then annealed at 1000ËC to 7 hours. The average diameter of the annealed fibers is 500 nm while the length of the annealed fibers is about 50 Âµm. The fibers were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and Cathodoluminescence (CL). PL spectra from the annealed SiC fibers show a broad emission in the red-infrared spectral regime. The main peak is centered at 774 nm while the shoulder on the left is at 740 nm
Characterization of Electromechanical Transduction in Polyelectrolyte Gels for Mechanical Sensor Applications
Authors: Prudnikova Katsiaryna , Utz Marcel 
Published: April 2011

AbstractWe report a new experimental method for the characterization of the electromechanical properties of polyelectrolyte gels (PG). PGs have been studied extensively, but with limited success, as mechanical actuators. However, they are also promising as potentially biocompatible mechanical sensors. In order to integrate them into actual devices, their electromechanical transduction properties need to be characterized in a reproducible manner.We have therefore developed a technique to measure the mechanically induced change in electrostatic potential in PGs. The polyelectrolyte gel is subjected to a well-defined pressure gradient by placing a thin, flat sample on a substrate with integrated concentric Platinum electrodes and indenting it with a spherical indenter. The potential values at the electrodes are measured using a MOSFET operational amplifier circuit with an input impedance of 1014 Ù and an effective dynamic range better than 16 bit. This method can be directly used to quantify electromechanical coupling in polyelectrolyte gels.
Effects of Al2O3 Nanopowder Filler Size on Glassy Polymeric Carbon Electrical Transport Behavior
Authors: Chhay Bopha , Minamisawa Renato Amaral , ILA Daryush 
Published: April 2011

AbstractGlassy polymeric carbon (GPC) has a unique graphite micro-fibril structure that attributes singular properties to the material. The addition of nanoparticles in the GPC matrix to improve its properties has been the focus of recent studies for spacecraft coating applications. We report the effects of Al2O3 nanoparticles dispersed in GPC on the electrical properties. The fabrication process to produce homogenous samples and the electrical measurements are fully described. In addition, the chemical structure characterization was evaluated using Raman spectroscopy.
The study of Thermal Resistant Enhancement of Siloxane-Modified LED Transparent Encapsulants
Authors: Chen Kai-Chi , Hsu Chia-Wen , Li Hsun-Tien 
Published: April 2011

ABSTRACTThermal resistant property of siloxane-modified epoxy compositions designed for long-term and high temperature storage was investigated. In this study, we developed two siloxane-modified epoxy compositions to improve the thermal stability of current epoxy encapsulants. One composition contained silicone epoxy, and the other one was cyclic aliphatic siloxane dianhydride.We selected triglycidyl ether terminated Phenylmethylsiloxnae-co-dimethylsiloxne (GT-1000), which was compatible with the diglycidyl ether of bisphenol A epoxy (Epon-828), to partial replaced the epoxy resin and was cured by liquid anhydride (MHHPA). In the mean time, we also synthesized 5, 5'-(1, 1, 3, 3-tetramethyl disiloxane-1, 3-dilyl)-bis-norborane-2, 3-dicarboxylic anhydride (A1) as a co-curing agent to cure Epon-828.The thermal resistance was studied by measuring the increase of yellow index (ΔYI) after thermal treatments. In 110 °C storage experiment for 1000 h, the ΔYI of GT-1000 0.2 equivalent was 1.51, whereas Epon-828/MHHPA (Comp 1) was 6.74. Moreover, The ΔYI of the composition with higher equivalent GT-1000 was only 2.15 after 2000 hours thermal aging. In the cyclic aliphatic siloxane dianhydride co-curing compositions, when A1 was 0.05 and 0.1 equivalent, the ΔYI was 2.28 and 0.72 after 1000 h, respectively. Compared with Comp 1, both GT-1000 and A1 were effective for thermal resistance.In IR-reflow test, the ΔYI of GT-1000/Epon-828/MHHPA= 0.5/0.5/1 was 0.65 and that of Epon-828/MHHPA was 1.49 after 260 °C for 10 seconds. The results revealed that either the siloxane-modified epoxy or siloxane-modified curing agent had excellent thermal resistant property for high performance LED applications.
Phase Separation in Al2O3 Sol-gel System Incorporated with High Molecular Weight Poly(ethylene oxide)
Authors: Tokudome Yasuaki , Nakanishi Kazuki , Fujita Koji , Miura Kiyotaka , Hirao Kazuyuki 
Published: April 2011

ABSTRACTPure alumina monoliths with well-defined macropores and mesostructured skeleton have been synthesized via a spontaneous route from the aqueous and ethanolic solution of aluminum salts in the presence of propylene oxide and high molecular weight poly(ethylene oxide)(PEO). The addition of propylene oxide to the starting solution controls the gelation, while the addition of PEO induces the phase separation. Appropriate choice of the starting composition, with which the phase separation and gelation concur, produces large-dimension (10mm×10mm×10mm), bicontinuous macroporous Al2O3 monoliths. The mean size of the continuously connected pores is controlled in the micrometer range, depending on the PEO concentration and polarity of the solution. On the other hand, micropores and mesopores, originated from the interstices among primary particles, exhibit median pore size of about 2.6 nm and the BET surface area as high as 396 m2/g after dried temperature at 40 °C.
Comparison of Different Reversed-Phase Packing Materials Based on Higher Organic Hybrid Particles
Authors: Lawrence Nicole L. , Wyndham Kevin D. , Glose Kenneth H. , Cook Jim T. , Brousmiche Darryl W. , Iraneta Pamela C. , Alden Bonnie A. , Boissel Cheryl A. , Walter Thomas H. 
Published: April 2011

ABSTRACTAs part of our ongoing exploration into the field of hybrid organic/inorganic particles as HPLC packing materials, we have recently evaluated the use of porous particles synthesized from the co-condensation of ethylene-bridged alkoxysilanes with tetraethoxysilane [1,2]. By employing 4-100 mol% of hybrid organic/inorganic groups (i.e., O1.5SiCH2CH2SiO1.5) to 96-0 mol% inorganic groups (i.e., SiO2), novel hybrid particles have been prepared and shown to be excellent materials for the preparation of efficient and chemically resilient reversed-phase packing materials.
Polymer Composite Reinforced with Nanodiamonds and Clay
Authors: Karbushev Valeriy V. , Konstantinov Ivan , Semakov Alexander , Parsamyan Irina , Kulichikhin Valery , Popov Vladimir 
Published: April 2011

ABSTRACTPolymer/clay and polymer/nanodiamond composites were prepared via solution dispersion, melt processing and new so-called colloid-deposition techniques. The following polymers have been used as matrices: hydroxypropylcellulose, polysulfone and styrene-acrylonitrile copolymer. For estimation of particles distribution in polymer matrices the optical microscopy, SEM and TEM methods were used. The X-ray results demonstrate that at least at some compositions, the technique employed was successful to intercalate the clay structure. It was found that particles addition (at small concentration) to polymeric liquids leads to decrease of viscosity. Tensile testing showed considerable improvements of mechanical properties.
Mesoporous Hybrid Thin Films: Building Blocks for Complex Materials with Spatial Organization
Authors: Soler-Illia Galo J. , Angelomé Paula C. , Fuertes M. Cecilia , Wolosiuk Alejandro , Bilmes Sara A. , López-Alcaraz Francisco Javier , Míguez Hernán 
Published: April 2011

ABSTRACTMesoporous Hybrid Thin Films (MHTF) of a variety of compositions and embedded organic functions are produced by combining sol-gel synthesis, template self-assembly and surface modification. One-pot or post-grafting strategies permit to modify the pore surface behavior. Highly controlled MHTF issued from a reproducible and modular synthesis can be used as building blocks for more complex structures, presenting order at larger scales, and novel properties derived from this multiscale order. Multilayer stacks of MHTF presenting specific and different functions and frameworks located in a well-defined position have been produced by combining sequential film deposition, selective functionalization and dissolution. These systems present new properties such as localized chemistry or modulable photonic crystal behavior.
Hybrid Nanoparticles Prepared by In-situ and Post-synthetic Surface Modification of Lanthanide-Based Nanoparticles with Phosphonic Acid Derivatives
Authors: Rill Christoph , Ivanovici Sorin , Kickelbick Guido 
Published: April 2011

ABSTRACTThe use of various phosphonic acid derivatives – some of which contain polymerizable groups – as surface modifying agents for nanoparticles was studied both in-situ during the synthesis of lanthanide-based (Ln = Nd, Eu, Yb) nanoparticles at room temperature as well as in a separate step after the particle preparation by a hydrothermal method. In the single-pot in-situ method the phosphonic acid esters served as growth-limiting agent during particle formation leading to small nanoparticles with a size of only a few nanometers as determined by dynamic light scattering as well as transmission electron and atomic force microscopy. Free phosphonic acids as well as their silyl esters were used to modify the hydrothermally prepared neodymium hydroxide nanorods which had diameters of approx. 20 nm and a length ranging up to a few micrometers. The surface modification was confirmed by infrared spectroscopy and thermogravimetric analysis.
Metal Oxide Nanocrystals: Building Blocks for Mesostructures and Precursors for Metal Nitrides
Authors: Niederberger Markus , Buha Jelena , Djerdj Igor 
Published: April 2011

ABSTRACTSol-gel routes to metal oxide nanoparticles in organic solvents under exclusion of water represent a valuable alternative to aqueous methods. In comparison to the complex aqueous chemistry, nonaqueous processes offer the possibility to better understand and to control the reaction pathways on a molecular level, enabling the synthesis of nanomaterials with high crystallinity and well-defined and uniform particle morphologies. The manifold role of the organic species in providing the oxygen for the oxide formation and in controlling the crystal growth and the assembly properties makes it possible to tailor the morphological, structural and compositional characteristics of the final inorganic products.In addition to metal oxides with nearly spherical crystallite sizes in the range of just a few nanometers, also more complex morphologies such as nanowire bundles, nanorods or lamellar organic-inorganic hybrids of varying hierarchical complexity can be achieved in one step and without the use of any surfactants. The spherical nanocrystallites are on the one hand versatile building blocks for the fabrication of fully crystalline and ordered mesoporous materials and on the other hand suitable precursors for the synthesis of metal nitride nanoparticles.This proceeding provides an overview of the various oxidic nanoparticles synthesized via the nonaqueous and surfactant-free sol-gel approach, summarizes the most frequently found formation mechanisms, and offers some insight into the crystallization pathway of nanoparticles. Furthermore, the use of metal oxide nanoparticles as nanobuilding blocks for the preparation of nano- and mesostructures as well as their transformation into metal nitride nanocrystals will be discussed.
Mechanical Behavior of Functional Hybrid Coating Based on Anisotropic Iron Oxide Nanoparticles
Authors: Chemin Nicolas , Rozes Laurence , Chanéac Corinne , Cassaignon Sophie , Jolivet Jean-Pierre , Barthel Etienne , Bourhis Eric Le , Sanchez Clément 
Published: April 2011

ABSTRACTFunctional hybrid coatings have been elaborated from a polymer matrix incorporating iron oxide nanoparticles. Stable aqueous suspensions of goethite (α-FeOOH) nanorods, obtained by controlled precipitation of Fe3+ ions, were introduced in 2-hydroxyethyl methacrylate (HEMA). The films were spin-coated on glass substrates from the solutions prior to a UV light induced free radical polymerization step. Nanoindentation tests were carried out to investigate the mechanical properties of the hybrid coatings. Swelling measurements and Fourier Transformed Infrared Spectroscopy (FTIR) were used to characterize the interface between the iron oxide nanoparticles and the PHEMA matrix. Cross-sectional scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was performed to evaluate the dispersion state of the iron oxide particles through the matrix. From a mechanical point of view, iron oxide nanorods yield to a strong reinforcement effect of PHEMA (increase in modulus and hardness by a factor 2 with 5%vol goethite nanoparticles). Origins of such reinforcement are attributed to the existence of highly favourable interactions at the goethite-PHEMA interface combined with a homogeneous dispersion of the particles. The nature of these interactions and evidences of there influence on the mechanical behaviour of the nanohybrid coatings are reported.
Fabrication of enamel-mimicking mineralization composite coating induced by electrolytic deposition (ELD) system
Authors: Fan Yuwei , Wang Rizhi , Moradian-Oldak Janet 
Published: April 2011

AbstractMature tooth enamel does not remodel nor self-repairs after damage. Therefore, in vitro formation of a uniquely ordered composite similar to enamel is of particular interest. In this study we applied a newly developed electrolytic deposition (ELD) system to promote the amelogenin nano-chain self-assembly and simultaneous calcium phosphate crystallization. Composite coatings of amelogenin-calcium phosphate were prepared on a cathode substrate (Si wafer), from an initial pH of 4-5, and calcium and phosphorus containing solution at room temperature. The effects of a recombinant full-length amelogenin (rP172) and truncated protein without the C-terminal (rP148) on the growth and morphology of the calcium phosphate nano-composite were investigated. A potentiostat was used to control the electrochemical parameters.Following the application of electric current, the local pH around the cathode was increased and resulted in the self-assembly of amelogenin that occurred simultaneously with calcium phosphate mineralization. Transmission and scanning electron micrographs of assembled rp172 amelogenin collected from the 25mM sodium phosphate solution during electrodeposition showed uniform nanospheres and nano-chains structures, while the rP148 formed irregular aggregates. SEM observation of the surface of the nano-composite after electrodeposition, revealed organized nano-rod structures in the presence of rP172, while only nano-sized spherical aggregates were seen in the presence of rP148. ATR-IR confirmed that the mineral phases were mainly octacalcium phosphate, but apatite and amorphous calcium phosphate were also present. Nanoindentation was tested on rP172 and rP148 composite coating. The rP172 composite coating exhibited higher elastic modulus and hardness than rP148 composite. The fracture toughness of rP172 composite was comparable to mature enamel. We therefore conclude that the 24 amino acid hydrophilic C-terminal of amelogenin is essential for the self-assembly, and therefore, for calcium phosphate crystal organization. The new electro-deposition system is effective for fabrication of amelogenin/apatite composites with defined organized structures.
Novel Vapor Phase biodegradable coatings for controlled drug delivery systems
Authors: Arjunan Arul Chakkaravarthi , Gupta Sushant , Singh Rajiv K , Singh Deepika , Opalko Jeff 
Published: April 2011

AbstractThe synthesis of nano-functionalized drug particles or drug particles with nanoscale biodegradable polymeric coatings has wider ranging applications in sustained release drug delivery systems. An important area of application includes delivery of drugs, such as proteins, peptides, and glucocorticoids via the inhalation process. The advantages of this method include, rapid absorption by the body and lack of metabolic degradation effects which is typically by some drugs during oral delivery. Here we discuss the novel pulsed laser and pulsed electron method to synthesize nanoscale biodegradable coatings of poly lactic acid (PLA) onto antiasthmatic drugs. In pulsed laser method a pulsed excimer laser ablates a thin layer of polymer which is deposited onto 1 -5 micron drug particles which are fluidized in the gas chamber. The control of the thickness, conformation and the chemistry of the nanoscale coating process will be discussed in detail. Applications of this methodology to delivery of anti asthamtic drugs and insulin will be discussed. The effect of polymer coating chemistry, molecular weight, hydrophobicity, and thickness on the sustained release characteristics will be discussed. A unique method for depositing the PLA films, pulsed electron beam deposition (PED) was used to deposit the films. This technique was tried done to overcome the difficulties like low absorption co-efficient of UV-laser. Method proved to be promising for producing smooth films and offers a better thickness control of the deposition. The RMS roughness and other morphological characteristics of PED deposited films were superior over the conventional laser ablated films.
A Combinatorial Approach Towards Functionalizing Copolymers with Effector Molecules that Attenuate Cyto-inflammatory Responses at the Biotic-abiotic Interface
Authors: Pierstorff Erik , Krucoff Max , Ho Dean 
Published: April 2011

AbstractFunctionalized copolymers offer the opportunity for tailored biology, where specific functionalities within these materials can be rapidly engineered on demand. Embedding effector molecules, for example, into these copolymers transforms an otherwise inactive component into a functional matrix for envisioned in vivo applications such as suppression of cellular inflammation/stress or immuno-regulatory implant coating, etc. Furthermore, our ability to utilize these copolymers in both a vesicular/planar configuration, coupled with their versatility in block composition empowers opportunities of utilizing vesicle-encapsulated effector molecules as dedicated drug delivery vehicles with targeting capabilities, or as modalities to replenish exhausted effector molecule stores within planar copolymer thin films. As such, these copolymeric membrane materials may potentially impact multiple medically-relevant fields in both scientific and technological contexts.An important element empowering this transition is the examination of the bio-inert properties of these materials. This includes the interrogation of the stress response of macrophages to the chemical/topographical stimuli presented by these materials. We have previously developed copolymers as neural implant coatings functionalized with a glucocorticoid anti-inflammatory Dexamethasone (Dex) using Langmuir-Blodgett deposition. This technology successfully suppressed, to a significant degree, RAW264.7 macrophage transcriptional machinery of several cytokines including TNFα, Il-6, and Il-12 analyzed using real time PCR (RT-PCR). These findings offered insight into both bio-abio material fabrication, as well as analysis of stress specific gene program activation which may be used to generate principles for optimizing neural implant biocompatibility and chronicity by attenuating innate immune responses.This study has broadened the range of applications of this material via its integration with a combination of intracellular signaling agonists (e.g. Liver X receptor-α/β (LXR α/β)) that function as non-steroidal anti-inflammatories to block transcriptional machinery associated with cell stress among other disorders. Here we demonstrate both planar encapsulation of an additional effector in the form of a robust, cell permeable LXRα/β agonist 3-((4-Methoxyphenyl)amino)-4-phenyl-1-(phenylmethyl)-1H-pyrrole-2, 5-dione using a crosslinked copolymer thin film. In addition, we investigated the underlying mechanisms of the attenuation of cellular inflammation via RT-PCR analysis of the resultant inhibition of lipopolysaccharide (LPS)-stimulated secretion of proinflammatory cytokine in murine macrophages. These advancements may potentially result in multi-functional nanoscale thin films that are chronically active, and can suppress cellular inflammation as implant coatings or bio-inert vesicular carriers of a non-steroidal pharmacological system.
Conductimetric Detection of Protein and Cancer Cells with Oxide Nanosensors
Authors: Goud Janagama , Raj P. Markondeya , Liu Jin , Iyer Mahadevan , Wang Z. L. , Tummala Rao 
Published: April 2011

AbstractSemiconducting oxides are widely known and commercially applied for their gas sensing properties. However, biochemical sensing has mostly depended on optical and electrochemical techniques that are more cumbersome. This work investigates the biosensing characteristics of ZnO nanobelts and ZnO thin films. Zinc oxide thin film sensors showed changes in conductivity after protein functionalization with rabbit IgG and hybridization with anti-rabbit IgG. Conductivity changes were also measured after coating the oxides with MCF-7 cancer cells and its antibodies. In another set of experiments, ZnO nanobelts showed systematic conductivity changes with rabbit IgG protein hybridization. The experimental results in this paper indicate that the conductimetric properties of nano and thin film oxides can be sensitized to protein and cancer cell hybridization reactions. This technique can also be applied to certain other pathogen proteins or toxic proteins from the environment leading to low-cost miniaturized wireless biosensors.
Mercury Detection with Ag Nanoparticles Reduced on Si Thin Films
Authors: Kalkan A. Kaan 
Published: April 2011

AbstractA surface plasmon resonance mercury sensor was demonstrated by electroless reduction of silver nanoparticles on amorphous silicon thin films. Unlike the previous Ag/Au nanoparticle - Hg interaction investigations, which monitored the blue shift of the dipolar plasmon band of well-dispersed nanoparticles, the present work reveals and explores the red shift of the symmetric hybrid plasmon mode of the interacting nanoparticles in response to Hg vapor exposure. Sensitivity to Hg was explored with varying nanoparticle size, which could be controlled by the immersion time associated with the reduction process. The recovery of the hybrid plasmon band after the Hg exposure was also monitored which was observed to be slower than the recovery of the dipolar plasmon band for noninteracting particles.
A Novel Efficient, Iodide-Free Redox Mediator for Dye-Sensitized Solar Cells
Authors: Zhang Zhipan , Chen Peter. Chaoyu , Zakeeruddin Shaik Mohammed , Moser Jacques-Edouard , Grätzel Michael 
Published: April 2011

AbstractA stable organic molecular radical, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), has been electrochemically studied and employed as a new redox mediator in nanocrystalline TiO2 dye-sensitized solar cells (DSCs) when it is doped with nitrosonium tetrafluoroborate (NOBF4). Reasonable photocurrents can be achieved despite of driving force of only 0.2 eV for the TEMPO/TEMPO+ system as compared to 0.6 eV for the iodide/triiodide redox system. Judicious selections of a 5 µm photoanode made from TiO2 mesoscopic particles (60 nm in diameter) and an organic sensitizer with high molar extinction coefficient yield an overall power conversion of 5.0 % under AM 1.5 illumination at 100 mW cm-2 and an incident photon-to-current conversion efficiencies (IPCE) in excess of 50 %.