bluuebunny/crossref_metadata_2025_split huggingface dataset:
Read-Shockley Grain Boundaries and the Herring Equation
Authors: Shekhar Shashank , King Alexander H. 
Published: April 2011

AbstractWe compute the strain fields and the interactions between dislocations at the junctions of classical small-angle grain boundaries. It is shown that, in contrast with the results for infinite small-angle boundaries, there are always forces acting on the dislocations in the arrays that define the grain boundaries, and that there is also an excess elastically stored energy associated with the triple junction (TJ). The forces on the dislocations and the excess stored energy of the TJ are shown to vary with the dihedral angles formed by the grain boundaries, and that the “equilibrium” dihedral angle based upon the Herring equation and the energies of the individual grain boundaries does not correspond to any kind of force or energy minimum. This relates to an unwarranted assumption in Herring's original derivation, that no interactions occur between the grain boundaries that make up a TJ.
Electric Field Assisted DNA Surface Reactions on the Sub-ms Timescale
Authors: Cabeca Ricardo , Prazeres D. M.F. , Chu V. , Conde J. P. 
Published: April 2011

AbstractThe on-chip application of single, sub-ms voltage pulses promotes the immobilization of single stranded DNA (ssDNA) probes from a solution to a chemically functionalized SiO2 surface and as well as the hybridization between ssDNA targets from a solution to covalently immobilized ssDNA probes (E-assisted DNA reactions). Compared to diffusion-based surface reactions (in the absence of the applied electric field), an improvement of several orders of magnitude in the kinetics of the immobilization and hybridization reactions is observed with low amplitude (below 2 V) and short duration (100 ns to 1 ms) voltage pulses. E-assisted DNA reactions are demonstrated using mm-size macroelectrodes and then optimized using μm-size microelectrodes.
Production of Highly Ordered Nanoporous Alumina and its Application in Cell Cultivation
Authors: Hoess Andreas , Staeudte Andrea , Thormann Annika , Steinhart Martin , Heilmann Andreas 
Published: April 2011

AbstractNanoporous alumina membranes were utilized as cell culture substrates. Two different anodization processes were applied in order to obtain highly ordered, self-supporting nanoporous alumina membranes. The resulting membranes exhibit uniform nanopores with constant diameters having aspect ratios (pore depth:pore diameter) larger than 1000. Tentative experiments evaluating the cellular interaction of a hepatoma cell line (HepG2) with the nanoporous alumina membranes will be described. Furthermore, cell proliferation as well as the adhesion behavior of the cells on the porous substrates was investigated. Scanning electron microscopy (SEM) and focused ion beam (FIB) technology were applied to examine the cell morphology. The experiments revealed that the nanoporous membranes can be used as cell culture substrates and that they have no adverse effects on cell proliferation and cell viability. Besides, cells on membranes with pore diameters larger than 200 nm developed small cell extensions (filopodia) which penetrated into the nanopores.
Electric Properties of the Co-nanodots using Kelvin Probe Force Microscopy
Authors: Yamamoto Shin-ichi 
Published: April 2011

AbstractWe have observed the assembly of a chemically adsorbed monomolecularlayer (CAM) into microwires, connections, and an electric path according to the location within field regions of a lithographically patterned array of two platinum (Pt) electrodes. A Pt electrode/monolayer/Pt electrode junction was fabricated by the self-assembly of a rigid monomolecular, namely 3-{6-{11-(Trichlorosilyl) undecanoyl} hexyl} thiophene (TEN) with thiophen groups, in the lateral direction between the Pt gap electrodes. The technique of a conductive probe AFM (CP-AFM) has been used to investigate the forward bias conduction properties of a TEN film grown by a wet process deposition on a glass substrate. The self-assembly depends on: (1) the ideal rigidity of the chemically adsorptive monomolecular layer (CAM) and (2) the strong affinity of the thiophen end groups of the CAM for the Pt electrode. The current–voltage (I–V) characteristics of the conjugated thiophen junction exhibited stepwise features at room temperature. From the results in the atmosphere, the conductivity of a lateral conjugated polythiophen group was calculated to be 5.0E4 S/cm.
Use of hydrogel microstructures as templates for protein immobilization
Authors: Koh Won-Gun , Kim Dae Nyun 
Published: April 2011

AbstractIn this study, protein micropatterns were created on the surface of three-dimensional hydrogel microstructures. Poly(ethylene glycol)(PEG)-based hydrogel microstructures were fabricated on a glass substrate using a poly(dimethylsiloxane) (PDMS) replica as a molding insert and photolithography. The lateral dimension and height of the hydrogel microstructures were easily controlled by the feature size of the photomask and depth of the PDMS replica, respectively. Bovine serum albumin (BSA), a model protein, was covalently immobilized to the surface of the hydrogel microstructure via a 5-azidonitrobenzoyloxy N-hydroxysuccinimide bifunctional linker, which has a phenyl azide group and a protein-binding N-hydroxysuccinimide group on either end. The immobilization of BSA on the PEG hydrogel surface was demonstrated with XPS by confirming the formation of a new nitrogen peak, and the selective immobilization of fluorescent-labeled BSA on the outer region of the three-dimensional hydrogel micropattern was demonstrated by fluorescence. A hydrogel microstructure could immobilize two different enzymes separately, and sequential bienzymatic reaction was demonstrated by reacting glucose and Amplex Red with a hydrogel microstructure where glucose oxidase was immobilized on the surface and peroxidase was encapsulated.
Molecular Motor-Based Assays for Altered Nanomechanical Function of Ca2+-Regulatory Proteins in Cardiomyopathies
Authors: Chase P. Bryant , Brunet Nicolas M. , Mihajlovic Goran , Xiong Peng , von Molnár Stephan 
Published: April 2011

AbstractWe propose that a thermo-electrical control system for rapid and reversible actuation of biomolecular motors and their partner filaments can also be used to study molecular mechanisms of cardiovascular diseases. We have previously used this device to evaluate the temperature-dependence of unregulated (absence of cardiac Ca2+-regulatory proteins tropomyosin, α-Tm, and troponin, Tn) actin filament sliding powered by myosin motors, which hydrolyze ATP. These assays using the thermo-electric controller can also be applied to regulated thin filaments (F actin plus α-Tm and Tn) to obtain energetic parameters and functional correlates of structural stability at the level of single filaments. This allows us not only to examine Ca2+-dependent sliding of thin filaments, but also to test for altered function of clinically relevant mutations of cardiac myofilament proteins such as those identified in familial hypertrophic cardiomyopathy (FHC).
Mechanical and Phase Transformation Behavior of Plastically Strained NiTi-based Shape Memory Alloys
Authors: Yu Peng , Li Qizhen 
Published: April 2011

AbstractThis paper examines the effect of plastic deformation on the strength and transformation heat and temperatures of the superelastic Nitinol samples. Two types of compression tests and differential scanning calorimetry tests were conducted. The first type of compression test deformed the samples to final fracture, and the second type included two loading –unloading cycles with or without plastic deformation. The mechanically tested samples were analyzed using differential scanning calorimetry.
From Feldspar Glass to Zirconia: State of the Art of Ceramics for Dental Applications
Authors: Denry Isabelle 
Published: April 2011

AbstractThe evolution of dental ceramics over the past four decades has been remarkable in light of the increase in the diversity of materials and fabrication techniques that have become available. As a consequence, the applications and indications for all-ceramic materials continue to expand. The purpose of the present article is to review the evolution of dental ceramics from the various aspects of crystalline phases, glassy matrix, flaws andin vivoperformance.
Structural and Mechanical Stability of Reduced Nickel Oxide/Yttria-stabilized Zirconia Anode/Electrolyte Structures for Solid Oxide Fuel Cell Applications
Authors: Biswas Somnath , Thangamani N. , Saraswathi N. T. , Zhang J. , Bandopadhyay S. 
Published: April 2011

AbstractHighly porous Ni-8YSZ anodes supported by a thin and dense electrolyte layer of 8YSZ have been developed for solid oxide fuel cell applications by reducing a NiO-8YSZ anode/electrolye precursor structure in a gas mixture of 5% H2-95% Ar at 800°C for selected time periods up to 8 h. It appears that 2 h of exposure to the reducing conditions is enough to reduce∼80% of NiO. XRD and SEM analyses in the reduced samples disclose the formation of the Ni-8YSZ cermet structure with desired porosity and microstructure. The porosity in the anode samples, which increases with the increase in the fraction of reduced NiO, severely affects the hardness and elastic moduli of the anode samples. Vickers indentation tests show that a hardness value of 5.5 GPa in the unreduced anode samples (12% porosity) reduces to less than 1 GPa in the 8 h reduced samples (36.68 % porosity). Similarly, a decrease of ˜44% in the Young's modulus and ˜40% in shear modulus is observed in the 8 h reduced samples through impulse excitation techniques, in comparison to the unreduced anode precursor. Since the elastic properties of fully dense Ni, NiO and YSZ are comparable to each other, the decrease in the magnitude in elastic moduli and hardness is attributed to the colossal increase in porosity as a result of the reduction of NiO in H2 atmosphere.
Electrical and optical responsivity of thin palladium films during hydrogen exposure
Authors: K Susan , Yalamanchili Kanthi , Kostanic Ivica N , Nazer Mohammed , Pozo de Fernandez Maria , McCay Mary H 
Published: April 2011

AbstractThis paper presents a series of measurements documenting changes in electrical and optical properties of thin palladium films. Palladium is deposited on the glass surface through plasma-assisted physical vapor deposition. This process produces highly uniform films with a surface variation of a few nanometers. The thicknesses of studied films range from 15 to 60 nm. The films are exposed to a constant flow of 2% hydrogen and 98% nitrogen mixture. During the exposure, film resistivity and its reflection properties in visible light were monitored. It is observed that the change in the film resistance during the hydrogen exposure depends on the film thickness. In particular, thicker depositions exhibit larger relative changes of the resistance. The reflectivity of the films in the white light changes during the hydrogen exposure as well. However, the change of the film reflectivity is observed to be independent of the deposition thickness. This paper presents observed measurements, their quantitative analysis and briefly discusses the use of findings in development of low-cost, single-use commercial grade hydrogen sensors.
Study of Ageing and Fluctuation Effects in MgB2Superconductor
Authors: Rajput Suchitra , Chaudhary Sujeet 
Published: April 2011

AbstractFor device applications of a superconducting material, its stability to ambient conditions is an issue of critical concern. The study of the ageing effects of the recently discovered intermetallic compound MgB2 is vital for knowing the degree of usefulness of this material. We report here the study of ageing and fluctuation conductivity behavior in bulk MgB2 pellets and stainless-steel sheathed, in-situ synthesized MgB2 tapes. A possible degradation mechanism is proposed based on ac-magnetic susceptibility and XRD investigations of MgB2 samples exposed to ambient over prolonged durations of time. In addition, the fluctuation induced conductivity behavior is also analyzed based on the observed resistivity (ρ)-vs-T measurements in MgB2 tape samples. This study indicated a three dimensional character of the MgB2 with reasonably good estimates of coherence the length. The scaling of fluctuation induced conductivity enhancement is also investigated from the ρ(H) vs T data obtained for different applied field strengths. These findings support the three-dimensional nature of thermodynamic fluctuations operative in MgB2 in contrast to that prevalent in several other high-temperature superconductors (HTSCs).
Plasma Texturing and Porous Silicon Mirrors for Epitaxial Thin Film Crystalline Silicon Solar Cells
Authors: Kuzma-Filipek Izabela Jozefa , Duerinckx Filip , Van Nieuwenhuysen Kris , Beaucarne Guy , Poortmans Jef 
Published: April 2011

AbstractThin film silicon solar cells, consisting of an epitaxially grown active layer on a low quality highly doped silicon substrate, incorporate many attractive features usually associated with their sister cells based on bulk silicon. However, the efficiency of the current epitaxial semi-industrial screen printed cells is limited to 11-12% mainly due to optical shortcomings. This paper will give an overview of our work aimed at tackling the 2 most important problems: (i) Finding and implementing an adequate front surface texture and (ii) the simulation, fabrication and incorporation of an intermediate reflector.The former issue has been addressed by the development of plasma texturing based on halogen species. This method allows us to fulfil the sometimes contradictory requirements for the textured surface, i.e. a uniform and reduced reflection, a strong lambertian character to scatter the light and a limited removal of silicon. It will be shown that the scattering efficiency is dependent on both the wavelength of the impinging light and on the silicon removal during the texturing process.The second and main issue of this work is the limited absorption volume of the epitaxial layer. To resolve this drawback, an intermediate reflector is placed at the epi/substrate interface to enhance the path length of the low energy photons through the epi-layer. In practice, a multi-layer porous silicon stack is created by electrochemical anodization of the substrate. The reflection at the epi/reflector/substrate interface is a combination of several different effects including a Bragg mirror and Total Internal Reflection (TIR). Measurements of the external reflectance as well as extraction of the internal reflection parameters are used to clarify the issue. Advanced structures, including chirped porous silicon stacks, are introduced. Finally, the benefits of the reflector on the level of the epitaxial silicon solar cell are analysed. Efficiencies close to 14% are obtained for epitaxial cells incorporating an advanced porous Si reflector.
New Light Management Concepts for Thin-Film Silicon Solar Cells
Authors: Stiebig Helmut , Haase Christian , Jorke Silvia , Obermeyer Philipp , Moulin Etienne , Schulte Melanie 
Published: April 2011

AbstractAn efficient utilization of the sun spectrum is a key issue in the field of thin-film silicon solar cell technology. Therefore, different strategies for enhanced light absorption were presented in the last years. In order to achieve a better understanding of light scattering at nanotextured interfaces the optical properties of a large variety of samples were studied. The angle resolved scattering behavior was analyzed by means of a developed ray tracing model. As an alternative to randomly textured substrates, the influence of periodically textured substrates on the light propagation in solar cells was experimentally and numerically studied with respect to improved light in-coupling and light trapping. Based on a deeper understanding a new tandem cell structure with a diffractive element between the top and bottom cell was developed. Finally, the influence of metallic nanoparticles on the cell performance was studied.
Periodic textures for enhanced current in thin film silicon solar cells
Authors: Haug Franz-Josef , Söderström Thomas , Cubero Oscar , Terrazzoni-Daudrix Vanessa , Niquille Xavier , Perregeaux Stephanie , Ballif Christophe 
Published: April 2011

AbstractFor thin film silicon solar cells it is vital to increase the optical path of light in the absorber because this allows for thinner cells with better stability and higher production throughput. We discuss the effect of periodically textured interfaces for the case of thin film silicon solar cells in n-i-p configuration using embossed plastic substrate which allows us studying the effect of a wide range of random or periodic textures. Due to the moderate thickness of the individual layers the texture is carried into each interface with a high degree of conformity even for the front contact which is the last layer. Solar cells on periodic structures show excellent performance; in a microcrystalline cell on a simple sinusoidal grating we achieved a gain in current density of 30%. Furthermore, the periodicity serves as a useful tool for the study of light management because the underlying phenomena like diffraction or grating coupling to plasma excitations of the metallic back reflector are governed by a relatively low number of well defined parameters like the periodicity and the amplitude of the grating.
Single Carrier Resonant Tunneling Design for Improving Carrier Collection in Quantum Confined Solar Cells
Authors: Alemu Andenet , Freundlich Alex 
Published: April 2011

AbstractPromising nanostructured device concepts with staggering theoretical efficiencies where quantum confined states are embedded in the intrinsic region of conventional p-i-n solar cells have been proposed. However, practical realizations remain inefficient as these devices suffer from an inherent difficulty in the extraction of photo-generated carriers from the confined states. Within the framework of a “single particle in the box” theory, such shortcomings could be addressed by the use of resonant quantum tunneling designs that can expedite carrier escape. Nonetheless, in material systems studied thus far, the implementation of such design becomes elusive as band offsets between the nanostructure and the host material are distributed between the conduction and valence band leading to the confinement of both holes and electrons (i.e. two particle problem). Our studies of such p-i-n Multi-Quantum Well (MQW) solar cells, only differing by their MQW region composition and geometry, have shown a strong dependence of device performance on quantum wells composition and thickness. Leveraging on the special property of dilute nitrides and using a carefully chosen material system and device design we show the possibility of circumventing this problem by separating the optimization of the valence and conduction band and reducing the issue to a single particle problem. Band structure calculations including strain effects, band anti-crossing models and transfer matrix methods are used to theoretically demonstrate optimum conditions for enhanced vertical transport. High electron tunneling escape probability, together with a free movement of quasi-3 D holes, is predicted to result in enhanced PV device performance. Furthermore, the increase in electron effective mass due to the incorporation of N translates in enhanced absorptive properties, ideal for PV application.
Electronic Structure and Photoemission in Plutonium Chalcogenides
Authors: Shick Alexander , Havela Ladislav , Gouder Thomas 
Published: April 2011

AbstractThe electronic structure of Pu chalcogenides is investigated making use of static around-mean-field LDA+U and dynamical LDA+HIA (Hubbard-I) methods. The LDA+U calculations provide correct non-magnetic ground state for PuX (X = S, Se, Te) with 5f-manifold non-integer filling (∼5.6(PuS)-5.7(PuTe)). This is an indication of a mixed valence ground state which is a combination of f5 and f6 multiplets. The photoelectron spectra are calculated in good agreement with experimental data. The 5f-manifold three-peaks feature near EF is well reproduced by LDA+HIA, and follows from mixed valence character of the ground state.
Scanning Transmission X-ray Spectromicroscopy of Actinide Complexes
Authors: Shuh David , Copping Roy , Tyliszczak Tolek , Castro-Rodriguez Ingrid , Shuh David K. 
Published: April 2011

AbstractThe fundamental characterization and understanding of 5f electron behavior in actinide complexes is imperative to provide an enhanced basis for the rational and accelerated development of improved processes relevant to nuclear energy. Soft x-ray absorption spectroscopy utilizing the scanning transmission x-ray microscope (STXM) at the Advanced Light Source-Molecular Environmental Science (ALS-MES) Beamline 11.0.2 has been used to probe the electronic characteristics of a nitrogen donor ligand 2,6-Bis(2-benzimidazyl)pyridine (BBP) and its resulting U(IV) complex. The nitrogen K- and carbon K-edges have been collected from both ligand and uranium complex, as well as the uranium 4d-edge from the complex. Upon complexation, the light element absorption spectra change markedly and the uranium spectra from the complex is compared to the reference spectrum obtained from U(IV)Cl4. The evolution of the spectral features are described and interpreted within a simple conceptual framework. Based on spectral evidence alone, the uranium is bound through the pyridine-like nitrogens and the oxidation state of the uranium is consistent with a U(IV) species.
Suppression of Hidden Order and Emergence of Ferromagnetism in URu2-xRexSi2
Authors: Butch Nicholas P. , Sayles Todd A. , Yukich Benjamin T. , Maple M. Brian 
Published: April 2011

AbstractMeasurements on URu2-xRexSi2 single crystals indicate that substitution of Re for Ru in URu2Si2 reduces the transition temperature of the hidden order state and quickly destroys superconductivity. At intermediate Re concentrations, weak ferromagnetism emerges and non Fermi liquid (NFL) behavior is observed in the low-temperature specific heat and electrical resistivity. A scaled Arrott analysis of the magnetization indicates the onset of ferromagnetism at x =0.15, where the hidden order disappears, and that the quantum phase transition is associated with novel critical exponents.
Physical Property Changes in Aging Plutonium Alloys
Authors: Chung Brandon W. , Thompson Stephen R. , Hiromoto David S. 
Published: April 2011

AbstractPlutonium, because of its self-irradiation by alpha decay, ages by means of lattice damage and helium in-growth. These integrated aging effects will result in microstructural and physical property changes. Because these effects would normally require decades to measure, studies are underway to asses the effects of extended aging on the physical properties of plutonium alloys by incorporating roughly 7.5 wt% of highly specific activity isotope 238Pu into the weapons-grade plutonium to accelerate the aging process. This paper presents updated results of self-irradiation effects on enriched and reference alloys measured from the immersion density, dilatometry, and mechanical tests. After nearly 90 equivalent years of aging, both the immersion density and dilatometry show that the enriched alloys at 35°C have decreased in density by ∼0.19 % and now exhibit a near linear density decrease, without void swelling. Both tensile and compression measurements show that the aging process continues to increase the strength of plutonium alloys.