bluuebunny/crossref_metadata_2025_split huggingface dataset:
Grain Boundary Conductivities of 0.58% Y203 Doped CeO2 Thin Films
Authors: Tian Chunyan , Chan Siu-Wai 
Published: April 2011

ABSTRACTWe have prepared Y2O3 doped CeO2 thin films on various substrates using electron beam evaporation. Both polycrystalline and single crystal-like textured films were shown by x-ray diffraction and transmission electron microscopy analyses. AC impedance spectroscopy was used to study the electrical properties of the films. The ionic conductivities of the films are dominated by grain boundaries, and higher as compared to that of a bulk material having the same dopant concentration sintered at 1500°C. The grain boundary conductivities of the films were investigated with regard to grain size, grain boundary impurity segregation, space charge on grain boundaries, and grain boundary misorientations. The contribution of grai boundary misorientation to the resistance of the grain boundary is considered to be negligible with respect to those of the impurity layer and space-charge layers. The grain boundary resistance may originate from the oxygen vacancy depletion in the space-charge layers.
Supercapacitors and Batteries
Authors: Goodenough J.B. , Lee Hee Y. , Manivannan V. 
Published: April 2011

ABSTRACTComparisons are made between the material requirements for supercapacitor electrodes and the cathode of a lithium-ion battery. The performances of the battery cathodes Li1+xFe2(SO4)2(PO4) and Li1+5 VMoO6 are compared to those for supercapacitor electrodes operating with 5.3 M H2SO4, Nafion 117, or 2 M KCl aqueous solution at pH 6.7. The use of a KCl aqueous electrolyte at mild pH allows stabilization of amorphous, hydrated electrode materials such as a-MnO2nH2O that are not stable in 5.3 M H2SO4 or with Nafion 117. However, the larger K+ ion appears to reduce by a factor of three the theoretical capacity attainable with H+ ions.
Photocatalysis Using Semiconductor Nanoclusters
Authors: Wilcoxon J.P. , Thurston T.R. 
Published: April 2011

AbstractWe report on experiments using nanosize MoS2 to photo-oxidize organic pollutants in water using visible light as the energy source. We have demonstrated that we can vary the redox potentials and absorbance characteristics of these small semiconductors by adjusting their size, and our studies of the photooxidation of organic molecules have revealed that the rate of oxidation increases with increasing bandgap (i.e. more positive valence band and more negative conduction band potentials). Because these photocatalysis reactions can be performed with the nanoclusters fully dispersed and stable in solution, liquid chromatography can be used to determine both the intermediate reaction products and the state of the nanoclusters during the reaction. We have demonstrated that the MoS2 nanoclusters remain unchanged during the photooxidation process by this technique. We also report on studies of MoS2 nanoclusters deposited on TiO2 powder.
Silica-Copper Molybdate Catalysts Prepared by Sol-Gel and Impregnation Methods: Reactivity and Spectroscopic Studies
Authors: Canevali C. , Morazzoni F. , Scotti R. , Cauzzi D. , Predieri G. , Moggi P. 
Published: April 2011

AbstractSilica-copper molybdates prepared by sol-gel and impregnation methods were tested as catalysts in the oxidation of propene at 400°C, both in a pulse and in a flow reactor. Their catalytic activity is connected to their structural features, as revealed by electron paramagnetic resonance (EPR) and X-ray diffraction (XRD) characterization.
Manipulation of Catalyst Structure for Molybdenum Trioxide by Chemical Etching
Authors: Zeng H.C. 
Published: April 2011

AbstractChemical etching method has been frequently used in defect investigation for crystalline materials in solid-state chemistry / physics and fundamental materials research. Recently, we apply this technique into catalytic materials fabrication. In this work, crystalline catalysts of orthorhombic MoO 3 have been prepared via a vapor phase deposition method and their crystallographic structure has been affirmed by XRD and FTIR investigations. A chemical etching method has been developed for restructuring these thermally processed catalysts. Using a 0.1 M NaOH etchant, {001} and {100} plane areas of the catalysts can be significantly increased while surface steps, ledges, and terraces are created upon this etching. Moreover, alternate crystal plane combinations of either {100} and {010}, or the {001} and {010} are observed on crystal edges and rectangular etch pits in the basal planes {010}. Technological merits and the processing parameters of this new method have also been identified. Following the findings of the current work, it is believed that the chemically carved surface structures may be crucial for certain MoO 3-involving catalytic reactions.
Combinatorial Screening of Anode and Cathode Electrocatalysts for Direct Methanol Fuel Cells
Authors: Reddington Epok , Yu Jong-Sung , Sapienza Anthony , Chan Benny C. , Gurau Bogdan , Viswanathan Rameshkrishnan , Liu Renxuan , Smotkin Eugene S. , Sarangapani S. , Mallouk Thomas E. 
Published: April 2011

AbstractProgress in several important electrochemical technologies, including batteries, fuel cells, sensors, and electrosynthesis, is currently materials-limited. A common feature of all electrode reactions is the imbalance (i.e., loss or generation) of ions at the electrode surface. We describe in this paper a method by which excess ions in the electrode diffusion layer can be imaged, and used to identify the best electrode materials from a combinatorial array of compositions.Although in principle this method can be applied to many electrochemical problems, we have focused on finding better electrocatalysts for direct methanol fuel cells (DMFCs). The DMFC performs two half-cell reactions: oxidation of methanol, and reduction of oxygen. Two of the most important problems in DMFCs are the poor performance of the electrocatalysts, and the crossover of methanol from the anode to the cathode side of the cell. An ideal situation would be the simultaneous development of two new catalysts: an anode that oxidizes methanol at low overpotential, and a “methanol-tolerant” cathode that reduces oxygen without oxidizing methanol.Based on previously developed rules for predicting the activity of ternary alloy catalysts (Ley, et al., J. Electrochem. Soc. 1997, 144, 1543), we began searching quaternary combinations of noble metals for the anode, and ruthenium selenide-type materials for the cathode reaction. The anode and cathode reactions generate and consume protons, respectively, creating a substantial pH gradient at the electrode surface. Changes in local pH are imaged by means of an appropriate fluorescent indicator: Ni-PTP for the anode and Eosin Y for the cathode. DMFC testing confirms the utility of the screening method, in that a Pt/Ru/Os/Ir quaternary catalyst was substantially superior to the best binary and ternary catalysts prepared under similar conditions.
Synthesis and Characterization of a New Family of Microporous Zirconium Silicates
Authors: Bern David S. , Bedard Robert L. , Broach Robert W. , Leon-Escamilla E. Alejandro , Gisselquist Jana L. , Plutht Joe 
Published: April 2011

AbstractA family of microporous zirconium-silicate framework materials designated as UZSi (UOP zirconium silicates) has been synthesized and structurally characterized. A general hydrothermal synthesis approach yielded a variety of known and novel zirconium-silicate topologies consisting of ZrOa23(oct) and SiO20(tet) units. A novel microporous framework (UZSi-9, Na2ZrSi3O9·x H2O) has been synthesized and structurally characterized. This framework contains A- and A-propeller units, which can also be found in the framework of the compositionally similar UZSi-1 1 (Na2ZrSi3O9·x H2O). Both UZSi-9 and UZSi-II adsorb and desorb water with a Type I microporous isotherm.
Synchrotron Infrared Microspectroscopy for Assessment of Mutagenicity of Metal Implants
Authors: Zhang Miqin , Holman Hoi-Ying N. , Ferrari Mauro , Hunter-Cevera Jennie C. 
Published: April 2011

AbstractA major concern in the development and implementation of metal implants for the clinical use is the assessment of material-induced mutagenesis. In this study we used synchrotron microspectroscopy in the mid-infrared region (4000-400 cm1 ) to non-invasively assess the in situ human cell responses to metal surfaces. Specifically we examined the subtle genetic aberrations of cells as they responded to a range of metals commonly used in metal prosthetic devices. Relative band intensities and band intensity ratios for functional groups of biomolecules that are inherent to the experimental system were examined. The molecular components of the biomolecules as they were perturbed by the interactions with metals were investigated. These results demonstrate the potential use of synchrotron FTIR microspectroscopy to screen the mutagenicity of metal implants.
Early Osteoblast Attachment, Spreading, and Focal Adhesions on RGD Coated Surfaces
Authors: Moodie G.D. , Ferris D.M. , Hertzog B.A. , Wimmer N. , Morgan H. , Chen C.Y. , Mathiowitz E. , Valentini R.F. 
Published: April 2011

AbstractCells recognize and interact with the extracellular matrix (ECM) through heterodimeric receptors known as integrins. The objective of our work is to immobilize integrin-stimulating peptides to bone-contacting implants in order to control cellular activity and response.We have previously demonstrated that cysteine (C) containing peptides self-assemble onto gold-coated substrates. Investigations have focused on the RGD (Arg-Gly-Asp) peptide sequence since it is found in several bone ECM proteins. Gold was first coated onto glass coverslips by evaporation and the peptide was applied in a 0.22 mM solution. Contact angle and surface plasmon resonance verified RGDC peptide attachment and formation of a monolayer.Rat calvarial osteoblasts isolated from six-day-old rat pups were used from passages one to three. Cell attachment at 20 minutes is 100% greater on RGDC than on CG (control peptides) or plain gold surfaces. Cells on RGDC also stain positively for vinculin, a protein which is present in focal adhesions (functional structures into which integrins assemble) whereas surfaces without integrin stimulating peptides do not. Scanning electron micrographs show cells to be more spread and have more processes at 20 minutes, 1, 3, and 24 hours on RGDC. Live video images of these surfaces from zero to three hours after plating confirmed earlier and greater cell spreading on RGDC.Ongoingin vitroexperiments are investigating the long-term response of osteoblasts to RGDC and other immobilized peptides in terms of differentiation, matrix production, and integrin expression.
In Vitro Biocompatibility Testing of Collagen-Calcium Phosphate Composites Using Human Bone Derived Osteoblasts
Authors: Lawson A.C. , Oyama M. , Emerton M.E. , Francis M.J.O. , Simpson A.H.R.W. , Czernuszka J.T. 
Published: April 2011

AbstractHuman bone derived osteoblasts were cultured on collagen-calcium phosphate composites. The ability of the substrates to support cell attachment, proliferation and bone formation was assessed using histochemical staining for alkaline phosphatase activity and immunolocalisation of transforming growth factor- β1and type 1 collagen. The effect of calcium phosphate phase and crystal size was investigated and the calcified samples compared with uncalcified collagen. Osteoblasts adhere to the collagen-calcium phosphate composites and express a mature osteoblast phenotype in vitro. Cell adhesion was greater on unmineralised collagen than on the mineralised composites, however, these cells were less differentiated. The presence of larger crystals seemed to have a detrimental effect on the cells, reducing proliferation and alkaline phosphatase activity. There was no discernible difference between the effect of hydroxyapatite and octacalcium phosphate on the cells.
Prospects for Chemical Control and Engineering of Organically Modified Ceramics
Authors: Rankin Stephen E. , McCormick Alon V. 
Published: April 2011

AbstractHydrolytic polycondensation of silicon alkoxides and organically modified alkoxides shows promise as a route to new materials for medicine. Mathematical models of this polymerization accelerate the development of these materials and processes for their production. With a reliable model, one can rapidly explore a wide variety of options for controlling material properties. Here we describe a model for kinetics of sol-gel copolymerization of a simple pair of ethoxysilanes: (CH3)3Si(OC2H5) and (CH3)2Si(OC2H5)2. We then describe how reactor configuration alone can be used to control of polymer structure by choosing how to mix the reactants. An example is shown of maximizing homogeneity at any reactor residence time of interest in the model copolymer system by using the time of addition of the faster-reacting monomer.
Porosity Evolution in Electrosurgical Blade Coatings
Authors: Konesky Gregory 
Published: April 2011

AbstractDuring Electrosurgery, Radio Frequency (RF) electrical power is applied to a cutting surface which cauterizes the incision. The desiccation of surrounding tissue results in hemostasis and surgery without bleeding. In the case of localized heavy bleeding, a coagulation process is employed using modulated RF power. However, substantial amounts of desiccated tissue may stick to the blade, undoing the achieved hemostasis, and possibly worsening the situation. To prevent this, various electrosurgical blade coatings have been developed to both permit the flow of RF power through the coating, and prevent desiccated tissue from sticking to it.PolyTetraFluoroEthylene (PTFE) is a commonly used electro- surgical blade coating that undergoes substantial surface morphology changes during use, eventually leading to failure. Highly conductive Diamond-Like Nanocomposite (DLN) electrosurgical coatings have been developed with the requisite non-stick characteristics and enhanced durability.After a brief review of electrosurgical fundamentals, the underlying mechanisms of operation of these two coating materials are compared. In the case of PTFE, establishment and evolution of porosity in the coating is essential to the flow of RF power, yet ultimately leads to long term degradation. Alternate conduction mechanisms for DLN coatings are considered.
Production and Characterisation of a Collagen-Calcium Phosphate Composite for Use as a Bone Substitute
Authors: Lawson A.C. , Czernuszka J.T. 
Published: April 2011

AbstractA composite for use as a bone substitute has been produced by the precipitation of calcium phosphate onto a collagen matrix. A collagen sheet is used as a membrane separating reservoirs of calcium and phosphate ions. The ions diffuse through the membrane and calcium phosphate precipitation occurs on and within the collagen matrix.Composites containing octacalcium phosphate or hydroxyapatite have been produced by varying the precipitation pH. If the correct balance of phosphate and calcium ion concentrations is achieved, precipitation occurs through the entire cross-section of the collagen sheet, giving a composite microstructure analogous to bone. The composite stiffness increases with increasing mineral content, reaching 2.8 GPa with 39 wt % mineral, when measured dry.
Development of a Multiple-Lumen Nerve Cuff Utilizing Growth Stimulant Patterns for Controlled Regeneration
Authors: Chen Y.S. , Miller C. , Greer M.H. , Quinones M. , Greer R.T. 
Published: April 2011

AbstractSilicone rubber multiple-lumen (ML) nerve cuffs were used for side-by-side comparisons of the effectiveness of two varieties of nerve growth stimulants (collagen gel and a gel mixture of collagen, fibronectin, and laminin) for regenerating cables across a 15 mm gap in 10 adult Sprague-Dawley rats. The filling pattern of the six tubes of the multiple-lumen portion of the cuff alternated with the collagen gel and the gel mixture of collagen, fibronectin, and laminin. After an 8 week implantation period, 53% (32 of 60) of the 0.5 mm diameter lumens displayed successful cable regeneration for both material fillings. The ML cuff experiments demonstrate the ability to bridge a 15 mm gap in the sciatic nerve of the rat by 8 weeks for relatively small diameter conduits in ML cuffs loaded with two varieties of growth stimulants. A more advanced organization including a smaller acellular region fraction and a higher vascularity is seen in the cables from the mixture-filled lumens compared to those in the cables from the collagen-filled lumens.
Interfacial Fracture Toughness of a Plasma Sprayed Hydroxyapatite Coating Used for Orthopedic Implants
Authors: Sugimura Y. , Spector M. 
Published: April 2011

AbstractThis study introduces a new method for evaluating the adhesion strength of a coating on a substrate. The interfacial fracture toughness, Γi is used to assess the work per unit area required to separate an interface. Γi is measured for the as-received specimens of hydroxyapatite plasma sprayed on Ti-6A1-4V substrate. Calculation of the interfacial fracture toughness requires that the elastic modulus of the coating to be known. The Young's modulus of the plasma sprayed hydroxyapatite is assessed using a bend test. The effect of aqueous environment on the interfacial fracture toughness is also investigated.
Novel Approaches to Microporous Membrane-Based Controlled Release
Authors: Farrell Stephanie , Sirkar Kamalesh K. 
Published: April 2011

AbstractMembrane-reservoir controlled release systems have been used for the delivery of a wide variety of therapeutic agents. Drug permeation is typically achieved by a solution-diffusion type of mechanism from a loaded reservoir region through a liquid-filled pore, and the rate of release is generally dependent on membrane porosity, tortuosity, and surface area. We have exploited the partition coefficient (between the reservoir liquid and the pore liquid phases) as an additional rate-controlling mechanism, and we have also extended the applications of membrane-reservoir systems to include delivery of microstructures such as liposomes.If the fluid that fills the pore of the membrane is chosen to be immiscible with the liquid in the reservoir phase, the drug partitions between the two phases at the interface between the reservoir and the pore. The partition coefficient may be exploited to provide rate control by reducing the driving force for diffusion across the fluid-filled membrane pore. The performance of this type of system is evaluated using benzoic acid in an organic reservoir phase, diffusing through water-filled membrane pores. Both hydrophilic and hydrophobic membrane materials were investigated. A hydrophilic membrane material afforded the advantage of a more stable water-filled pore phase.Controlled delivery of liposomal structures may also be achieved using a porous membranereservoir device. The pores of the membrane must be large enough to permit the passage of the liposomes, which are transported by simple Brownian motion. This concept is demonstrated using a porous polycarbonate membrane system, which was chosen to minimize interaction between the membrane and the liposomes.
Fast X-ray Measurement System for Structural Study in Zr60Al15Ni25 Supercooled Liquid
Authors: Sato S. , Matsubara E. , Waseda Y , Zhang T. , Inoue A. 
Published: April 2011

AbstractA fast x-ray measurement system adopting the geometry of the Debye-Scherrer camera in combination with an imaging plate has been developed for the structural study of supercooled liquid. We carried out the anomalous x-ray scattering (AXS) measurement as well as the ordinary x-ray diffraction measurement with this system in Zr60Al15Ni25 supercooled liquid at 720K above the glass transition temperature (693K). A whole diffraction profile of very good counting statistics that even fits to the AXS analyses is obtained for a very short time (≅600s). The analyses of scattering data observed in the Zr60Al15Ni25 supercooled liquid for various annealing times in this system provide us information on a change of local atomic structures in the liquid state.
Compositional Dependence of Thermal Stability and Soft Magnetic Properties for Fe-Al-Ga-P-C-B Glassy Alloys
Authors: Mizushima T. , Makino A. , Yoshida S. , Inoue A. 
Published: April 2011

AbstractStructure, glass forming ability and soft magnetic properties for Fe-Al-Ga-P-C-B glassy alloy system were investigated in the compositional range of Fe from 69 to 78 at%, (Al+Ga) from 2 to 12 and (P+C+B) from 17 to 28. The saturation magnetization (σ5) rises gradually with increase of Fe concentration. The maximum value of 70K for supercooled liquid region (ΔTx=Tx-Tg, Tx: crystallization temperature, Tg: glass transition temperature:) and the maximum thickness of 180 μm for glass formation (tmax,) are found in the composition range around Fe=70at% and (Al+Ga)=7at%. The highest permeability (μc) of 20,000 at 1kHz and the lowest coercive force (Hc) of 2 A/m at the sample thickness of 30 μm can be also obtained at this composition. It was ascertained that the composition regions to yield the maximum glass forming ability and lowest magnetostriction were in agreement with that in which the most excellent soft magnetic properties were yielded. This results allow us to assume that the excellent soft magnetic properties for this glassy alloy system in the limited composition range are presumably due to high structural homogeneity resulting from significantly high glass-forming ability.
Fracture in Bulk Amorphous Alloys
Authors: Horton J. A. , Wright J. L. , Schneibel J. H. 
Published: April 2011

AbstractThe fracture behavior of a Zr-based bulk amorphous alloy, Zr-10 Al-5 Ti-17.9 Cu-14.6Ni (at.%), was examined by transmission electron microscopy (TEM) and x-ray diffraction forany evidence of crystallization preceding crack propagation. No evidence for crystallizationwas found in shear bands in compression specimens or at the fracture surface in tensile specimens.In- situ TEM deformation experiments were performed to more closely examine actualcrack tip regions. During the in-situ deformation experiment, controlled crack growth occurredto the point where the specimen was approximately 20 μm thick at which point uncontrolledcrack growth occurred. No evidence of any crystallization was found at the crack tips or thecrack flanks. Subsequent scanning microscope examination showed that the uncontrolledcrack growth region exhibited ridges and veins that appeared to have resulted from melting. Performing the deformations, both bulk and in-situ TEM, at liquid nitrogen temperatures (LN2) resulted in an increase in the amount of controlled crack growth. The surface roughness of the bulk regions fractured at LN2temperatures corresponded with the roughness of the crack propagation observed during the in-situ TEM experiment, suggesting that the smooth-appearing room temperature fracture surfaces may also be a result of localized melting.
Mechanism for Light Emission During Fracture of a Zr-Ti-Cu-Ni-Be Bulk Metallic Glass: Temperature Measurements in Air and Nitrogen
Authors: Gilbert C. J. , Ager J. W. , Schroeder V. , Ritchie R. O. 
Published: April 2011

AbstractLight emitted during rupture of Zr41.2Ti13.8Cu12.5 Ni10Be22.5 (at%) bulk metallic glass has been investigated. Charpy V-notch specimens fractured in a pendulum impact apparatus were used to excite light emission. Spectra acquired from rupture in air exhibited a single broad peak and were fit to a blackbody temperature of ∼3175 K. In nitrogen, however, light emission was no longer visible to the eye. In this case, the captured light was at least four orders of magnitude less intense, and spectra were shifted to the red with an effective blackbody temperature of ∼1400 K. Fracture surfaces generated in both air and nitrogen exhibited local melting, providing further evidence of intense heating during fracture. Based on these observations we argue that the intense light emission in air is associated with pyrolysis of fresh material exposed during rupture. Results were compared to preliminary observations of light emission from ribbons of a Zr57Nb5Ni12.6Cu15.4Al10 (at%) glass.