bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Combinatorial Electropolymerization to the Development of Chemical Sensors
Authors: Mirsky Vladimir M. , Kulikov Valentin , Hao Qingli , Wolfbeis Otto S. 
Published: April 2011

ABSTRACTCombinatorial electropolymerization with electrical addressing was realized on the array of 96 electrode groups, each from four electrodes. The polymer synthesis was combined with subsequent high-throughput investigation of analytical properties of synthesized polymers. Two-and four-point techniques were applied simultaneously to measure electrical properties of synthesized polymers and contact resistances between electrodes and polymers and modifications of these parameters on addition of analyte. The system was used for development of sensitive materials for detection of gaseous hydrogen chloride.
Applications of Discrete and Gradient Compositions in Polymer Research
Authors: Wroczynski Ronald J. , Potyrailo Radislav A. , Pickett James E. , Rubinsztajn Malgorzata 
Published: April 2011

ABSTRACTA new general approach for rapid performance screening of polymer compositions is provided. Multiple compositions are generated as one-dimensional libraries in a micro-extruder with step or gradient composition changes in < 1 min. To accelerate testing, an environmental stress is applied to only local regions, followed by high-sensitivity spatially resolved characterization. Applying the methodology to weathering of arrays of polymeric compositions provided a 20X faster ranking of polymer/UV absorber compositions that was equivalent to traditional weathering methods.
Modeling the Rheology of Commercial Long Chain Branched Polymer Melts
Authors: Park Seung Joon , Larson Ronald G. 
Published: April 2011

ABSTRACTThe predictions of a general “hierarchical model” for the rheology of general mixtures of linear and branched polymers are compared to experimental data for well-defined long-chain branched polymers. For a wide range of branched polymer melts, which include star-linear blends, H-polymers, and comb polymers, the predictions of the model agree well with experimental data. We apply the hierarchical model to metallocene-catalyzed polyethylenes (mPEs), in which the branched structures are generated by a Monte Carlo method based on the known reaction kinetics. The hierarchical model captures the shape of the curves of viscoelastic moduli vs. frequency of mPEs well and predicts accurately the effect of long chain branching on the linear viscoelastic properties. The quantitative agreement of the hierarchical model prediction with experimental data of well-defined long-chain branched polymers and mPEs shows that information on branching structure could be inferred from rheological measurements on combinatorial sets of mixtures of an unknown branched with different combinations of linear polymers.
High Throughput Screening of the Thermal Stability of Colorants in a Polycarbonate Matrix
Authors: Whisenhunt Donald W. , Carter Randall , Shaffer Ron , Bulsiewicz William , Flanagan William 
Published: April 2011

ABSTRACTThe relative thermal stability of 44 colorants of interest to GE Plastics as polymer colorants was determined. The effects of common (non-colorant) additives on the thermal stability in a polymer matrix were also determined. The measurements were carried out by reflectance spectrometry on thin films of polymers that had been subjected to heating cycles. The change in the visible spectrum was used as an indicator of thermal stability. This paper discusses the method and overall results for the experiments.
Fiber-Optic Sensor Technology and Combinatorial Chemistry
Authors: Geissinger Peter , Prince Barry J. , Kaltcheva Nadejda T. , Prince Maureen J. , Schwabacher Alan W. 
Published: April 2011

ABSTRACTOur recently introduced “Fiber-Optic Combinatorial Chemistry” technique combines combinatorial synthetic methods and optical fiber sensor technologies. Our one-dimensional combinatorial chemistry method allows for synthesis of large compound libraries in a linear format, for example in the cladding of optical fibers. Subjecting these libraries to assays that indicate positive identification of a library member by the binding of a fluorescent group, produces, in effect, an optical fiber sensor array. The location of a particular fluorescent region along the optical fiber can be determined through the optical time-of-flight technique, in which laser pulses propagating through the fiber core probe through their evanescent fields the fluorescent properties of the compounds located in the fiber cladding. It is a virtue of our combinatorial synthetic procedure that with the location of a compound on the fiber, its synthetic history is immediately known. We demonstrated that limitations on the spatial resolution of compounds along the fiber due to the excited state lifetimes of the fluorescent marker molecules can be overcome by the use of a second fiber - evanescently coupled to the first one - as an optical delay.The existing claddings of optical fibers severely restrict the range of chemistries for the synthesis of combinatorial libraries. Therefore, in order to make our method more generally applicable, the existing fiber cladding has to be replaced by a porous material that can act as solid support for reactions and at the same time preserve the optical guiding conditions of the fiber. In this contribution we discuss the requirements for such a replacement cladding and evaluate the general suitability of a functionalized candidate material.
Controlled deposition of wedge-shaped profiles for thin (∼10Å) layers by pulsed laser deposition
Authors: Christen H.M. , Ohkubo I. 
Published: April 2011

ABSTRACTA method yielding precisely controlled thickness profiles in thin-film growth is necessary for continuous compositional spread techniques. While multiple approaches have been introduced and successfully tested, some specific applications require the use of very thin “wedge”-type profiles (∼10 Å at the thickest point), while at the same time yielding lateral sample sizes of several centimeters. Here we introduce the basic principles of a pulsed-laser deposition based approach utilizing the translation of the substrate behind a slit-shaped aperture and demonstrate by simple calculations that this method can satisfy these requirements.
High-Throughput Screening of Flux Materials for Single Crystal Growth by Combinatorial Pulsed Laser Deposition
Authors: Takahashi R. , Tanigawa T. , Yamamoto Y. , Yonezawa Y. , Matsumoto Y. , Koinuma H. 
Published: April 2011

ABSTRACTWe propose a new concept and method for high throughput screening of flux materials used in the bulk single crystal growth. The concept of our tri-phase epitaxy has been generalized as the flux-mediated epitaxy with the aid of quick optimization of flux materials in the combinatorial thin-film technology. Here, we report on the successful discovery of a new flux composition of Bi-Ti-Cu-O for the growth of high-quality Bi4Ti3O12 bulk crystal and thin film.
Analytical TEM Observations of Combinatorial Catalyst Libraries for Hydrogen Production – As a Part of “MATERIOMICS”–
Authors: Akita T. , Ueda A. , Yamada Y. , Ichikawa S. , Tanaka K. , Kohyama M. , Kobayashi T. 
Published: April 2011

ABSTRACTMateriomicsis a new approach combining combinatorial surveys and precise structure analyses in order to develop new functional materials efficiently. In this paper, we show the first stage of materiomics applied to metal/metal oxide catalysts. The catalytic activities of various metal/metal oxide catalysts for hydrogen production have been examined by a combinatorial method, and TEM observations have been performed for the selected catalysts from the libraries in order to estimate the structures in the combinatorial surveys. A Pd/MnO2catalyst shows the high activity for the water gas shift reaction, where thin Pd oxide layers about 1–2nm thickness are formed on the flat MnO2surface. However, Pd oxide layers are reduced and metallic Pd particles 2–3nm in diameter with narrow size distribution are formed after hydrogen reduction. The structure of manganese oxide support also changes after hydrogen reduction. On the other hand, both Pd particles with diameters of 2–3nm and 10–20nm on SiO2show low activity for the water gas shift reaction. Thus, it is concluded that the catalytic activity does not simply depend on the particle size of metals, but that the interaction between metals and metal oxide supports is also important for the catalytic performance.
Search and Synthesis of New Family of Quasicrystals
Authors: Ishimasa Tsutomu , Kashimoto Shiro , Maezawa Ryo 
Published: April 2011

ABSTRACTStarting from the Zn17Sc3 cubic approximant, new icosahedral quasicrystal was searched by substituting Zn by other metals, M, at the alloy composition of Zn75M10Sc15. In the cases of M = Mn, Fe, Co, Ni, Pd, Pt, Ag and Au, new P-type quasicrystals were discovered in as-cast alloys. In the cases of M = Fe, Co, Ni, Pd and Ag, the quasicrystals are thermodynamically stable at approximately 700 °C. This result indicates that use of an approximant crystal as a starting material is very efficient way to search new quasicrystal alloy, and many kinds of metals stabilize the quasicrystal structures; i.e. noble metals and transition elements including Mn, Fe, Co and Ni in addition to Mg. Taking the variety in base metals of Tsai-type approximants into account, this variety in additional components suggests many possibilities of undiscovered quasicrystals. The equality ofthe electron concentration, ela ≈ 2.1, in Hume-Rothery rule may be a guide to these quasicrystals.
Synthesis of Quasicrystal Phases by Mechanical Alloying of Ti45+xZr38-XNi17 (-4≤ X ≤16) Powder Mixtures, and Their Hydrogen Storage Properties
Authors: Takasaki Akito , Imai Naoki , Kelton Kenneth F. 
Published: April 2011

ABSTRACTMechanical alloying of Ti45+xZr38-xNi17 (-4 ≤ x ≤ 16) elemental powder mixtures leads to the formation the amorphous phase, but subsequent annealing at 833 K causes the formation of icosahedral (i) quasicrystal and the Ti2Ni-type crystal phases. The α-Ti phase is also produced in Ti-rich powders after annealing. Both the quasilattice constant of the i-phase and the lattice parameter of the Ti2Ni-type crystal phase decrease monotonically with increasing substituted amount of Ti because of the smaller radius of the Ti atom. The maximum hydrogen concentration in the i-phase in all powder compacts, after electrochemical hydrogenation in a KOH solution, is almost the same, about 63 at% ([H] / [M] ≈ 1.7). The onset temperature of hydrogen desorption is about 570 K (at a heating rate of 5 K/min) for all powders, but the temperature for the maximum hydrogen desorption rate increases with increasing Ti concentration in the powders, suggesting that some hydrogen atoms might be more strongly bound in the quasilattice where the original Zr sites become occupied by Ti atoms.
Hydrogen Diffusion in Quasicrystalline ZrCuNiA1
Authors: Apih T. , Klanjsek M. , Khare Varsha , Jeglic P. , Dolinsek J. 
Published: April 2011

ABSTRACTThe hydrogen diffusion constant D in the hydrogenated quasicrystalline alloy ZrCuNiAl has been determined using the technique of NMR diffusion in a static fringe field of a superconducting magnet. The diffusion constant of partially quasicrystalline Zr69.5Cu12Ni11Al7.5 exhibits a significant decrease with increasing hydrogen-to-metal ratio H/M, owing to creation of defects in the lattice during hydrogen loading, which dominates over the site-blocking effect. The actual alloy structure—the amorphous, icosahedral or approximant—appears to be less important for the hydrogen diffusivity.
Path to Strong Insulating Transport Properties in Bulk AlPdRe Samples
Authors: Rosenbaum Ralph , Zhong Yuan-Liang , Lina Juhn-Jong 
Published: April 2011

ABSTRACTElectronic transport measurements have been made on bulk icosahedral Al70Pd22.5Re7.5 quasicrystal (QC's) samples, having increasingly larger resistance temperature ratios, rT = R(4.2 K)/R(292 K). Data were taken between 0.023 K to 292 K and in magnetic fields up to 17.9 T. Both the zero field resistivity and the magnetoresistance (MR) changed from metallic behavior to weakly insulating behavior to highly insulating behavior, as the resistance temperature ratios rT's of the samples were made larger. For the insulating samples, the resistivities ρ's followed simple inverse temperature power laws above 50 K going as ρ(T) = a0/Tz, where z = 1 ± 0.1.The insulating QC samples exhibited saturation behaviors of their resistivities below 2 K. Below 0.3 K, the strongly insulating QC's displayed activated variable-range hopping (VRH) laws in their conductivity; the hopping exponents y's in the VRH laws varied between 0.19 ≤ y ≤ 0.43. A simple model including conductivity contributions both from the primary insulating QC phase and from a secondary metallic phase yielded good fits to the resistivity and MR data.
Topological and Chemical Short-Range Order in Undercooled and Stable Melts of Al13(Co,Fe)4 Alloys
Authors: Holland-Moritz Dirk , Schenk Thomas , Simonet Virginie , Bellissent Robert 
Published: April 2011

ABSTRACTThe short-range order of stable and deeply undercooled liquids of Al13(Co,Fe)4 alloys forming polytetrahedral phases is investigated by combining the containerless processing technique of electromagnetic levitation with elastic neutron scattering. Partial structure factors were inferred from the diffraction data which allow an analysis of both, the topological and the chemical short-range order of these alloy melts as a function of the temperature.
Metastable States During Devitrification of a Zr70Pd20Cu10 Metallic Glass
Authors: Kramer M. J. , Sordelet D. J. 
Published: April 2011

ABSTRACTHigh energy synchrotron x-rays (124.63 keV) are used to investigate the initial stages of the devitrification for the Zr70Pd20Cu10 metallic glass prepared by melt-spinning (MS). Due to the excellent signal:noise, we are able to determine the initial nucleating phase by analyzing the differences in the total scattering function S(Q) as a function of time at a temperature ∼ 50 K below the crystallization temperature. The alloy undergoes a structural relaxation prior to nucleation and growth. Devitrification proceeds from nucleation of the icosahedral phase. The differential pair distribution function (dPDF) indicates that the as-quenched alloy may have icosahedral-like order which undergoes local rearrangement to true icosahedral order at an annealing temperature 50 K below the crystallization temperature. More importantly, time-resolved high-energy synchrotron is shown to have excellent sensitivity to the initial atomic rearrangements preceding nucleation in metallic glasses.
The ω Phase Formation during Laser Cladding and Remelting of Quasicrystal Forming AlCuFe on Pure Aluminum
Authors: Biswas Krishanu , Chattopadhyay Kamanio , Galun Rolf , Mordike Barry L. 
Published: April 2011

ABSTRACTWe report the formation ω phase in the remelted layers during laser cladding and remelting of quasicrystal forming Al65Cu23.3Fe11.7 alloy on pure aluminum. The ω phase is absent in the clad layers. In the remelted layer, the phase nucleates at the periphery of the primary icosahedral phase particles. A large number of ω phase particles forms enveloping the icosahedral phase growing into aluminum rich melt, which solidify as α-Al solid solution. On the other side it develops an interface with aluminum. A detailed transmission electron microscopic analysis shows that ω phase exhibits orientation relationship with icosahedral phase. The composition analysis performed using energy dispersive x-ray analyzer suggests that this phase has composition higher aluminum than the icosahedral phase. The analysis of the available phase diagram information indicates that the present results represent large departure from equilibrium conditions. A possible scenario of the evolution of the ω phase has been suggested.
Morphology of Sn Films Grown on the Fivefold Surface of Icosahedral Al63Cu24Fe13 Investigated by Scanning Tunneling Microscopy
Authors: Sharma H. R. , Shimoda M. , Barrow J. A. , Ross A. R. , Lograsso T. A. , Tsai A. P. 
Published: April 2011

ABSTRACTSn film growth on the fivefold surface of icosahedral Al63Cu24Fe13 has been investigated by employing scanning tunneling microscopy. For about monolayer coverage, the deposited Sn forms a layer of monoatomic height. A Fourier transform of the layer's structure reveals quasicrystalline long range order. At higher coverage, flat-topped clusters of uniform heights are formed. The clusters preferentially grow at the step edges.
Swift Heavy Ion Irradiation on Quasicrystals
Authors: Chatterjee Ratnamala 
Published: April 2011

ABSTRACTThe present level of understanding of the effects of irradiation of quasicrystalline targets with swift heavy ions has been reviewed here. The results of systematic deposition of large amount of energy densities (12 keV/nm < (dE/dx)e < 40 keV/nm) in Al-Cu-Fe based system are discussed in terms of resistivity measurements (in-situ measurements of resistivity changes with increasing flux (ions/cm2) and ex-situ resistivity vs temperature measurements before and after irradiation) & standard and high-resolution X-ray diffraction measurements made before and after irradiation. The studies are aimed at understanding the changes that may occur in these alloys as a result of the relaxation of such highly excited states of matter. Also, we attempt to learn whether such changes are typical to the long-range quasicrystallinity of the system or not.
Microstructural Design by Controlled Crystallization of Metallic Glasses
Authors: Köster Uwe , Janlewing Rainer 
Published: April 2011

ABSTRACTNanocrystalline materials can be produced e.g. by high energy ball milling or vacuum condensation; these methods require powder compaction as a final step. In another route - the nano-crystallization - metallic glasses are used as precursors for nanocrystalline materials without any porosity. The conditions for achieving an ultra-fine grained material by crystallization are small growth, but large nucleation rates. Whereas in Fe-Ni-B glasses the finest microstructure is produced at annealing temperatures above the glass transition close to the maximum of the nucleation rate, in Zr-based metallic glasses nanocrystallization was found to proceed only at relatively low temperatures below the glass transition. The aim of this contribution is to study systematically the micromechanisms involved in the microstructural design.Crystallization was studied in detail in Fe-Ni-B and Zr-based metallic glasses by means of TEM, X-ray diffraction and DSC. Nucleation and growth rates were estimated from crystallization statistics. By modeling the obtained time-dependent nucleation rates in the framework of diffusion controlled classical nucleation all relevant crystallization parameter could be derived. Using these data TTT-diagrams could be drawn and annealing conditions deducted, e.g. for the formation of a nanocrystalline alloy.Isothermal DSC plots for polymorphic crystallization can only be explained with a very significant decrease in the growth rate at later stages. Such a decrease is assumed to result from stresses building up during crystallization beyond the percolation limit for the crystalline phase; under this condition stresses resulting from the volume change during crystallization cannot be compensated by viscous flow as in the case of isolated crystals in an amorphous matrix.
Catalytic Properties of High-Density Monodispersive Metal Nanostructures
Authors: Gurevich Sergey A. , Yassievich Irina N. , Kozhevin Vladimir M. , Yavsin Denis A. , Zabelin Mihail A. , Tret'yakov Pavel A. , Rostovshikova Tat'yana N. , Smirnov Vladimir V. 
Published: April 2011

ABSTRACTWe report on ultra-high catalytic activity of high-density monodispersive Cu and Ni nanostructures fabricated by newly developed laser electrodispersion technique. In these structures the particle sizes are 5 nm for Cu and 2.5 nm for Ni (relative size dispersion is less than 20%). Due to fast cooling during particle formation Cu and Ni grains have amorphous structure. The catalytic activity of Cu-based structures were studied in chlorohydrocarbons transformations reactions, while Ni structures were tested in the reaction of 1-nonene hydrogenation. The measured catalytic activity vs. particle surface density dependencies exhibit a maximum corresponding to densely packed one-layer granulated films. About an order of magnitude increase in the catalytic activity is observed when increasing the dielectric permittivity of the reactant solution. It is suggested that the observed high catalytic activity is due to thermally activated interparticle electron tunneling, which results in the appearance of negatively and positively charged particles in densely packed granulated films.
Development of Amorphous Metals Using High Throughput Experiments
Authors: Eric Ramberg C. , Wang Y. , Fan Q. , McDermott E. , Wang J. , Kenyon K. , Hornbostel M. , Guan S. , Nguyen S. 
Published: April 2011

ABSTRACTHigh throughput, thin film synthesis and screening methods have been developed to investigate potential bulk metallic glass (BMG) compositions. Physical vapor deposition (PVD) was used for sample synthesis. A novel screening tool was developed to measure changes in resistance vs. temperature of these thin film samples. Example data for 34 compositions in the Mg-rich region of the Mg-Cu-Y ternary system are presented.
New Calcium Based Bulk Metallic Glasses
Authors: Senkov Oleg N. , Mike Scott J. 
Published: April 2011

ABSTRACTThermal properties of a number of new Ca-based bulk metallic glasses are reported and discussed here. The compositional range of the new metallic glasses follows the formula:CaA(Y,Ln)B(Mg,Sn)C(Ga,Zn,Al,Ag)D(Cu,Ni)E,where A ranges from 0.40 to 0.70, B = 0 to 0.25, C = 0 to 0.25, D = 0 to 0.35, E = 0 to 0.35, A+B+C+D+E=1, and Ln represents the La group elements. The alloys have been developed based on specific criteria predicted from Senkov-Miracle topological and thermodynamic models for metallic glass formation, which narrow the compositional range for searching new metallic glasses.
Quenched-in Free Volume Vf, Deformation-induced Free Volume, the Glass Transition Tg and Thermal Expansion in glassy ZrNbCuNiAl measured by Time-resolved Diffraction in Transmission
Authors: Yavari A. R. , Tonegaru M. , Lupu N. , Inoue A , Matsubara E. , Vaughan G. , Kvick Å. , Botta W.J. 
Published: April 2011

ABSTRACTUsing high-precision X-ray dilatometry, we have succeeded in directly measuring excess quenched-in free-volume Vf in metallic glasses. The method was applied to the very easy glass forming Zr57Nb5Cu15.4Ni12.6Al10 (Vit 106). The annealing out of the order of 0.5% free volume was observed during heat treatment of rapidly solidified glassy ribbons. Excess free volume was also generated by heavy deformation and observed to anneal out during heat treatment. Once the excess free volume anneals out, the glass transition Tg appears clearly as a break in the x-ray dilatation curves as the glass goes over to the supercooled liquid region prior to crystallization at Tx.
Topological and Chemical Short-Range Order in Undercooled and Stable Melts of Al13 (Co,Fe)4 Alloys
Authors: Holland-Moritz Dirk , Schenk Thomas , Simonet Virginie , Bellissent Robert 
Published: April 2011

ABSTRACTThe short-range order of stable and deeply undercooled liquids of Al13(Co,Fe)4 alloys forming polytetrahedral phases is investigated by combining the containerless processing technique of electromagnetic levitation with elastic neutron scattering. Partial structure factors were inferred from the diffraction data which allow an analysis of both, the topological and the chemical short-range order of these alloy melts as a function of the temperature.