bluuebunny/crossref_metadata_2025 huggingface dataset:
The competitive advantage of business units: Evidence from the integrated circuit industry
Authors: Corsino Marco , Passarelli Mariacarmela
Published: September 2009

Abstract Within‐business diversification, product strategies, and competitors' innovative behavior may affect the competitive advantage of business units that operate in the integrated circuit industry. This investigation employs original data about new product introductions and sales from a representative sample of companies. In addition, the study's empirical taxonomy can deal with significant product heterogeneity, which many previous contributions overlook. Econometric analysis shows that corporate diversification within a market segment affects the competitive advantage of constituting units positively. Increased product variety also enables business units to gain a competitive edge over rivals. However, new product introductions by sister units in other market niches impair the performance of a focal unit. A higher propensity to innovate among rival firms also erodes the advantage of a focal unit, whereas positive spillovers arise from other firms' innovations in neighboring market segments.
Critical incidents in R&D alliances: Uncovering leadership roles
Authors: Kaulio Matti A. , Uppvall Lars
Published: September 2009

Abstract What keeps an alliance leader awake during night? Past alliance research has contributed to our understanding of aspects such as motives for forming an alliance, initial conditions and the process of development. However, few studies have investigated challenges that alliance leaders face, as well as roles they adopt during the alliance life cycle. In this paper, we seek to investigate critical incidents that alliance leaders face in the execution of contract‐based R&D alliances. By using the Critical Incident Technique, 158 critical incidents have been collected and analyzed. Our findings show that, in terms of frequency of occurrence, managing informal relationships and alliance formation are the two dominant themes, followed by formal R&D process, embeddedness, and exit. In addition, four crucial roles for managing an R&D alliance are also suggested. These roles are Facilitating, Finishing, Ambassadoring, and Trustkeeping.
The Promise of Follow-on Biologics to Spur Both Biologic Drug Innovation and Competitive Prices
Authors: Wroblewski Michael S. , Jex Elizabeth A.
Published: September 2009

Recent debates over how to structure an approval pathway at the United States Food and Drug Administration for follow-on biologics (FOBs) have taken a predictably polarized turn, with the pioneer drug manufacturers on one side, and the FOB industry on the other. Each side is arguing for statutory entry restrictions in the form of exclusivity periods that they argue will promote innovation and consumer access to lower-priced biologic drug products. These entry barriers are based on those in the Hatch-Waxman Act's approval process for generic small-molecule drugs. Recently, the Federal Trade Commission (FTC) provided an independent analysis of how the proposals would likely affect consumers. The FTC's Report, Emerging Health Care Issues: Follow-On Biologic Drug Competition, concluded that the likely market dynamics of FOB competition will resemble brand-to-brand drug competition, rather than a generic drug product. This article explains how an FOB regulatory approval pathway need only rely on the US patent system and market-based pricing to continue to incentivize development of both pioneer and FOB drugs. Further, inclusion of entry barriers in the form of regulatory exclusivity periods and special patent resolution procedures would likely harm consumers by delaying FOB entry and decreasing the pace of biotech innovation.
Competing Technology Options and Stakeholder Interests for Tracking Freight Railcars in Indian Railways
Authors: Srivastava Shirish C , Mathur Sharat S , Teo Thompson SH
Published: September 2009

This teaching case examines the implementation of a new technology for tracking individual freight railcars (wagons) by Indian Railways. After exploring multiple ‘technological options,’ the Indian Railways decided to undertake a pilot project based on time-tested Automatic Equipment Identification system using Radio Frequency Identification (RFID) technology. However, a number of other technological options are now available, which include EPC Gen2-based RFID systems, Global Positioning System solutions, Optical Character Recognition (OCR)-based systems, and manual hand-held data collection devices integrated with the current Freight Operations System. Each of these systems has its own advantages and limitations. Although Indian Railways officials are going ahead with the pilot project, they are uncertain as to the appropriate technological choice, given the wide range of available technology options. Further, they are faced with competing interests from different stakeholder groups (departments), who favor different technologies.
Analysis of enantiotopic discrimination in the NMR spectra of prochiral solutes in chiral liquid crystals by symmetry factorization of the Saupe ordering matrix
Authors: Lesot Philippe , Aroulanda Christie , Luz Zeev
Published: September 2009

The enantiotopic discrimination in the NMR spectrum of prochiral molecules dissolved in chiral liquid crystals (CLCs) is governed by the ordering of the solute molecules. The lifting of the spectral degeneracy of enantiotopic sites in such solvents stems from the nonequivalence in their effective ordering. This, in turn, is brought about by a change in the directions (or the equivalence) of the principal axes of their ordering tensor, relative to those in achiral liquid crystals. This discrimination mechanism can only occur for solute molecules belonging to a limited number of (“allowed”) improper point groups, viz., D2d, C2v, Cs, and S4 [D. Merlet, J. W. Emsley, P. Lesot, and J. Courtieu, J. Chem. Phys. 111, 6890 (1999)]. In this work it is shown that the ordering tensor of such prochiral solutes in CLC, SCLC, and likewise, the tensors, Tk, describing the anisotropic magnetic resonance interactions of enantiotopic pairs, can be partitioned into symmetric and antisymmetric (and irrelevant) parts. The NMR results in such solvents can be cast into separate sets of equations depending on either the symmetric or the antisymmetric parts of SCLC and Tk. The discrimination observed in such solvents depends only on the latter set of equation, while the former applies to the average splitting of enantiotopic pairs as well as to diasterotopic or homotopic sites in the prochiral molecules. The factorization procedure greatly facilitates the analysis of the ordering properties of prochiral solutes in CLC and provides new insight on the discrimination mechanism. In particular, it allows correlation between independent enantiotopic partners and the identification of NMR signals belonging to common prosterogenic faces in the molecule. Expressions relating NMR observables with the symmetric and antisymmetric parts of SCLC are derived for each of the four allowed groups. Model examples are presented and discussed.
Comparison of SiO2, Si3N4, As2S3, and Ge0.25Se0.75 dielectric layers for InP- and GaAs-based material systems for midinfrared quantum cascade laser waveguides
Authors: Rehouma G. , Evans C. A. , Ikonić Z. , Indjin D. , Harrison P.
Published: September 2009

We present in this paper a direct comparison of the optical properties of InP- and GaAs-based quantum cascade laser waveguides operating in the midinfrared wavelength range. The absorption loss and optical confinement were calculated using a two-dimensional electromagnetic finite-element method. The effect on the waveguide properties of SiO2, Si3N4, As2S3, and Ge0.25Se0.75 used as electrical insulation layers is investigated. The results indicate that a careful choice of this particular layer according to the geometrical structure and the emission wavelength should enhance the laser performance.
Small single-crystal silicon cantilevers formed by crystal facets for atomic force microscopy
Authors: Nakagawa Kazuhisa , Hashiguchi Gen , Kawakatsu Hideki
Published: September 2009

We have developed a batch fabrication method of small cantilevers formed by crystal facets of single-crystal silicon for improving the sensitivity of atomic force microscopy. In order to realize a small cantilever with a very sharp tip, we have employed KOH anisotropic etching and local oxidation of silicon. We have made two types of small cantilevers, the V-shaped triangular type and the bulk triangular type. The length of each cantilever is 20 μm. The tip of the V-shaped type is bridged by two wires with thickness of 0.6 μm. The bulk triangular type has a thickness of 1.5 μm. The frequency characteristics of the cantilevers vibrated using photothermal excitation were measured by laser Doppler velocimetry. The resonance frequency of the V-shaped type and the bulk triangular type were 687 kHz and 8.42 MHz, and their spring constants are estimated to be 0.7 N/m and 370 N/m, respectively.
Optimum electromagnetic heating of nanoparticle thermal contrast agents at rf frequencies
Authors: Hanson George W. , Patch S. K.
Published: September 2009

Enhanced heating of nanoparticles for applications such as thermoacoustic imaging and therapeutic heat delivery is considered. The optimum electrical conductivity to achieve maximum electromagnetic energy deposition in a given nanoparticle is obtained, with emphasis on rf frequencies, where plasmon resonances associated with negative permittivity are generally not possible. Spheres, coated spheres, nanowires, and carbon nanotubes are considered. In all cases, it is found that relatively small conductivity values (e.g., σ⪡1 S/m for spheres) provide the maximum absorption of rf energy, and thus maximizes heat production in the nanoparticle. Therefore, lossy dielectrics may be a better choice for maximizing nanoparticle heat production than metallic particles.
On the enhanced Raman scattering of the nanosize semiconductor: A couple of cylinders (silicon and silver)
Authors: Wu Y. B. , Wang Y. F. , Cao X. W.
Published: September 2009

Raman enhancement in a couple of nanocylinders (one made of silicon and one made of silver) has been calculated in our work. A formulation for enhanced Raman scattering of semiconductor cylinders is presented. The numerical calculation result based on the formulation indicates that the couple of nanocylinders (one made of silicon and one made of silver) can enhance the electric field in the silicon cylinder greatly and shows strong enhancement for volume average compared with bulk silicon. The largest enhancements per unit volume approach 107 times as compared with bulk crystalline silicon. The silicon and silver nanocylinder structures can combine useful features of the resonant excitations of silicon cylinder and the effect of resonant interaction between silicon cylinder and silver cylinder. This leads to the giant enhancement in the field inside the silicon cylinder and hence an increased Raman scattering. Moreover the results indicate that the interaction between the silicon cylinder and the silver cylinder is very strong under proper conditions.
Sheath expansion and plasma dynamics in the presence of electrode evaporation: Application to a vacuum circuit breaker
Authors: Sarrailh P. , Garrigues L. , Hagelaar G. J. M. , Boeuf J. P. , Sandolache G. , Rowe S.
Published: September 2009

During the postarc dielectric recovery phase in a vacuum circuit breaker, a cathode sheath forms and expels the plasma from the electrode gap. The success or failure of current breaking depends on how efficiently the plasma is expelled from the electrode gap. The sheath expansion in the postarc phase can be compared to sheath expansion in plasma immersion ion implantation except that collisions between charged particles and atoms generated by electrode evaporation may become important in a vacuum circuit breaker. In this paper, we show that electrode evaporation plays a significant role in the dynamics of the sheath expansion in this context not only because charged particle transport is no longer collisionless but also because the neutral flow due to evaporation and temperature gradients may push the plasma toward one of the electrodes. Using a hybrid model of the nonequilibrium postarc plasma and cathode sheath coupled with a direct simulation Monte Carlo method to describe collisions between heavy species, we present a parametric study of the sheath and plasma dynamics and of the time needed for the sheath to expel the plasma from the gap for different values of plasma density and electrode temperatures at the beginning of the postarc phase. This work constitutes a preliminary step toward understanding and quantifying the risk of current breaking failure of a vacuum arc.
Diameter dependence of modulus in zinc oxide nanowires and the effect of loading mode: In situ experiments and universal core-shell approach
Authors: He Mo-Rigen , Shi Y. , Zhou W. , Chen J. W. , Yan Y. J. , Zhu J.
Published: September 2009

Uniaxial tensile measurements have been performed on [0001]-oriented zinc oxide nanowires (NWs) with diameters ranging from 18 to 204 nm using a homemade in situ mechanical testing system. Diameter dependence of tensile modulus (TM) is further compared with that of bending modulus (BM, shown earlier). With diameters of NWs decreasing in an intermediate range (about 30–120 nm), TM increases slower than BM, while it gets close to the latter with diameters decreasing below 30 nm; for rather large diameters, they both tend to the bulk modulus. A core-shell model is developed based on diameter-dependent and radial-distributed elastic stiffening in NWs and well explains our experimental results.
Deformation of a droplet in a particulate shear flow
Authors: Ardekani A. M. , Dabiri S. , Rangel R. H.
Published: September 2009

A numerical simulation using a distributed-Lagrange-multiplier-based computational method is conducted in order to investigate the deformation and breakup of a droplet in a particulate shear flow. A level-set method is used to track the interface and model the surface tension. The results show that the presence of particles leads to larger droplet deformation and a perforation in the center of the droplet. It is found that the critical Stokes number above which a perforation occurs increases linearly with the inverse of the capillary number and viscosity ratio.
Single laser pulse induced dynamic magnetization reversal mechanism of perpendicularly magnetized L1 FePt films
Authors: Liu X. D. , Xu Z. , Gao R. X. , Chen Z. F. , Lai T. S. , Du J. , Zhou S. M.
Published: September 2009

In order to measure photoinduced dynamic magnetization reversal by single laser pulse, alternating magnetic field is synchronized with the femtosecond laser pulse such that the magnetization state is reset before each single laser pulse. For perpendicularly magnetized L10 FePt films, the dynamic magnetization reversal process is accompanied by the nucleation of reversed domains and the barrierless transient domain wall motion at low magnetic fields and subsequent pinned domain wall motion at the switching field. The switching field does not change with the pump-probe delay time.
Contribution of d-band electrons to ballistic transport and scattering during electron-phonon nonequilibrium in nanoscale Au films using an ab initio density of states
Authors: Hopkins Patrick E. , Stewart Derek A.
Published: September 2009

Electron-interface scattering during electron-phonon nonequilibrium in thin films creates another pathway for electron system energy loss as characteristic lengths of thin films continue to decrease. As power densities in nanodevices increase, excitations of electrons from sub-conduction-band energy levels will become more probable. These sub-conduction-band electronic excitations significantly affect the material’s thermophysical properties. In this work, the role of d-band electronic excitations is considered in electron energy transfer processes in thin Au films. The electronic structure and density of states for gold are calculated using a plane wave pseudopotential density function approach. In thin films with thicknesses less than the electron mean free path, ballistic electron transport leads to electron-interface scattering. The ballistic component of electron transport is studied by a ballistic-diffusive approximation of the Boltzmann transport equation with input from ab initio calculations. The effects of d-band excitations on electron-interface energy transfer are analyzed during electron-phonon nonequilibrium after short pulsed laser heating in thin films.
Morphological transition and emulsification failure in globular microemulsions
Authors: Shimokawa N. , Komura S.
Published: September 2009

We consider the condensation transition of microemulsion droplets of oil which are dispersed in water in the presence of surfactant. Since a macroscopic oil phase is formed due to this transition, it is called “emulsification failure.” Based on the free energy approach, we determine the transition lines between the spherical and the cylindrical droplet phases as well as the phase boundary lines of the emulsification failure. The phase diagrams are calculated by changing the physical properties of the surfactant monolayer such as the saddle-splay modulus and the spontaneous curvature. For a negative saddle-splay modulus, the spherical droplet phase coexists with the excess oil phase. In some cases, a re-entrant transition (sphere→cylinder→sphere) is expected to take place. For a positive saddle-splay modulus, the system undergoes a direct transition from the cylindrical droplet phase to the macroscopically phase separated state. The sphere-to-cylinder transition line approaches the emulsification failure boundary as the saddle-splay modulus becomes larger.
Ion-beam-induced chemical disorder in GaN
Authors: Ishimaru Manabu , Zhang Yanwen , Weber William J.
Published: September 2009

Atomistic structures of high-energy ion irradiated GaN were examined using transmission electron microscopy (TEM). Single crystalline GaN substrates were irradiated at cryogenic temperatures with 2 MeV Au2+ ions to a fluence of 7.35×1015 Au/cm2. Cross-sectional TEM observations revealed that damaged layers consisting of amorphous and nanocrystalline phases are formed at the surface and buried depth of the as-irradiated GaN substrate. Atomic radial distribution functions of the amorphous/polynanocrystalline regions showed that not only heteronuclear Ga–N bonds but also homonuclear Ga–Ga bonds exist within the first coordination shell. It was found that the ratio of heteronuclear-to-homonuclear bonds, i.e., the degree of chemical disorder, is different between the surface and buried damaged layers. The alternation of chemical disorder was attributed to the difference in the defect formation processes between these layers.
Dissociative excitation transfer in the reaction of O2(a1Δg) with OH−(H2O)1,2 clusters
Authors: Viggiano Albert A. , Midey Anthony , Eyet Nicole , Bierbaum Veronica M. , Troe Jürgen
Published: September 2009

Rate constants for the dissociation of OH−(H2O) and OH−(H2O)2 by transfer of electronic energy from O2(a1Δg) were measured. Values of 1.8×10−11 and 2.2×10−11 cm3 molecule−1 s−1, respectively, at 300 K were derived and temperature dependences were obtained from 300 to 500 K for OH−(H2O) and from 300 to 400 K for OH−(H2O)2. Dissociative excitation transfer with OH−(H2O) is slightly endothermic and the reaction appears to have a positive temperature dependence, but barely outside the uncertainty range. In contrast, the reaction of OH−(H2O)2 is exothermic and appears to have a negative temperature dependence. The rate constants are analyzed in terms of unimolecular rate theory, which suggests that the dissociation is prompt and is not affected by collisions with the helium buffer gas.
Transparent self-assembled films of reduced graphene oxide platelets
Authors: Zhu Yanwu , Cai Weiwei , Piner Richard D. , Velamakanni Aruna , Ruoff Rodney S.
Published: September 2009

Transparent conducting films have been fabricated in one step, combining self-assembly and chemical reduction of graphene oxide platelets dispersed in water. The films are of centimeter scale and their thickness can be controlled by the concentration of the graphene oxide suspension. The optical transmittance values at a wavelength of 550 nm were 87% and 96% for the films made from 1.5 and 0.5 mg/ml suspensions, respectively, and have sheet resistances of 11.3 and 31.7 kΩ/◻. Scanning and transmission electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy were used to characterize the films.
Advanced multiple time scale molecular dynamics
Authors: Omelyan Igor P.
Published: September 2009

A novel method for integrating the equations of motion in molecular dynamics simulations of many-particle systems is proposed. It is based on canonical transformations of the phase space and high-accuracy reversible decompositions of the time evolution propagator into terms with different time scales. This allows one to efficiently overcome the limitations imposed on the efficiency of the integration in standard multiple time stepping algorithms. As is demonstrated for a particular case of the Lennard-Jones fluids, the precision of the simulations within the method presented can be increased by several orders of magnitude already at typical computational costs and time steps.
Coordinate transformation and matrix measure approach for synchronization of complex networks
Authors: Juang Jonq , Liang Yu-Hao
Published: September 2009

Global synchronization in complex networks has attracted considerable interest in various fields. There are mainly two analytical approaches for studying such time-varying networks. The first approach is Lyapunov function-based methods. For such an approach, the connected-graph-stability (CGS) method arguably gives the best results. Nevertheless, CGS is limited to the networks with cooperative couplings. The matrix measure approach (MMA) proposed by Chen, although having a wider range of applications in the network topologies than that of CGS, works for smaller numbers of nodes in most network topologies. The approach also has a limitation with networks having partial-state coupling. Other than giving yet another MMA, we introduce a new and, in some cases, optimal coordinate transformation to study such networks. Our approach fixes all the drawbacks of CGS and MMA. In addition, by merely checking the structure of the vector field of the individual oscillator, we shall be able to determine if the system is globally synchronized. In summary, our results can be applied to rather general time-varying networks with a large number of nodes.
Study of phase transition of two-dimensional ferroelectric copolymer P(VDF-TrFE) Langmuir monolayer by Maxwell displacement current and Brewster angle microscopy
Authors: Ou-Yang Wei , Weis Martin , Chen Xiangyu , Manaka Takaaki , Iwamoto Mitsumasa
Published: September 2009

Phase transition of ferroelectric Langmuir monolayers composed of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer with various VDF ratios, was investigated. The thermodynamic, dielectric, and structural properties of these two-dimensional ferroelectric systems were analyzed by coupling surface pressure-area isotherms, Maxwell displacement currents (MDCs), and Brewster angle microscopy (BAM) images. A low-temperature phase transition, specific for the ferroelectric monolayer, was found out with an order-disorder phase transition. The phase transition temperature was dependent on the composition ratio of the copolymer, and the Gibbs free energy reached maximum at this temperature. A negative MDC peak representing dipole moment oriented to the subphase was observed during monolayer compression and disappeared above the order-disorder transition. Interestingly, the BAM images showed decrease of domain size with increase of temperature. These results were well explained based on the order-disorder transition.
Stable transport in proton driven fast ignition
Authors: Bret A.
Published: September 2009

Proton beam transport in the context of proton driven fast ignition is usually assumed to be stable due to proton high inertia, but an analytical analysis of the process is still lacking. The stability of a charge and current neutralized proton beam passing through a plasma is therefore conducted here, for typical proton driven fast ignition parameters. In the cold regime, two fast growing modes are found, with an inverse growth rate much smaller than the beam time of flight to the target core. The stability issue is thus not so obvious, and kinetic effects are investigated. One unstable mode is found stabilized by the background plasma proton and electron temperatures. The second mode is also damped, providing the proton beam thermal spread is larger than ∼10 keV. In fusion conditions, the beam propagation should therefore be stable.
Coulomb blockade behavior in an indium nitride nanowire with disordered surface states
Authors: Aravind K. , Su Y. W. , Ho I. L. , Wu C. S. , Chang-Liao K. S. , Su W. F. , Chen K. H. , Chen L. C. , Chen C. D.
Published: September 2009

We present electron transport phenomena in a single electron transistor based on an individual indium nitride nanowire. Meticulous Coulomb oscillations are observed at low temperatures. While the device shows single period Coulomb oscillation at high temperatures or at high bias voltages, additional satellite peaks along with the main Coulomb peak appear at low temperatures and low bias voltages. The quasiperiodic structure is attributed to the mixing of dissimilar Coulomb oscillations arising from two serially coupled islands embedded inadvertently in the surface metallic states of the nanowire. The proposed model is numerically simulated with good agreement with the experimental data.
High-temperature continuous-wave operation of low power consumption single-mode distributed-feedback quantum-cascade lasers at λ∼5.2 μm
Authors: Xie Feng , Caneau Catherine G. , LeBlanc Herve P. , Visovsky Nick J. , Coleman Sean , Hughes Lawrence C. , Zah Chung-en
Published: September 2009

Continuous-wave operation of a distributed-feedback quantum-cascade laser in a packaged module is demonstrated up to a heat sink temperature of 80 °C with an output power of greater than 10 mW and a power consumption of less than 3.8 W. Single longitudinal mode emission near 5.24 μm is observed over a temperature range from 10 to 80 °C with a side mode suppression ratio greater than 20 dB limited by the instrumentation. A single spatial mode is determined with far-field pattern measurement. The above performance is achieved using a buried heterostructure and a small cavity of 7.6 μm×1.5 mm.
Theory of polyzwitterion conformations
Authors: Kumar Rajeev , Fredrickson Glenn H.
Published: September 2009

Conformational characteristics of polyzwitterionic molecules in aqueous solutions are investigated using the variational method. Analytical relations are derived for the radius of gyration of a single polyzwitterionic chain as a function of the chain length, electrostatic interaction strength, added salt concentration, dipole moment, and degree of ionization of the zwitterionic monomers. In the absence of the small ions (counterions and coions) near the polyzwitterionic chain, attractive dipole-dipole interactions are shown to induce a collapse of the polyzwitterionic chain. However, in the presence of the small ions, the radius of gyration is shown to be an interplay of the screening of the electrostatic interactions and the counterion adsorption on the zwitterionic sites. In addition to the well-known Debye–Hückel screening of the charge-charge interactions, screening of the charge-dipole, and dipole-dipole interactions are found to play important roles in determining the size of the chain. Functional forms for the screened charge-dipole and dipole-dipole interaction potentials are presented. Furthermore, counterion adsorption on the zwitterionic monomers is predicted to be asymmetric depending on the nature of the added salt and the zwitterionic groups. Qualitative remarks regarding the solubility of these molecules in aqueous solutions along with the classical “antipolyelectrolyte” effect (increase in the solubility in water with the addition of salt) are presented.
Unraveled mechanism in silk engineering: Fast reeling induced silk toughening
Authors: Wu Xiang , Liu Xiang-Yang , Du Ning , Xu Gangqin , Li Baowen
Published: September 2009

We theoretically and experimentally study the mechanical response of silkworm and spider silks against stretching and the relationship with the underlying structural factors. It is found that the typical stress-strain profiles are predicted in good agreement with experimental measurements by implementing the “β-sheet splitting” mechanism we discovered and verified, primarily varying the secondary structure of protein macromolecules. The functions of experimentally observed structural factors responding to the external stress have been clearly addressed, and optimization of the microscopic structures to enhance the mechanical strength will be pointed out, beneficial to their biomedical and textile applications.
Parameter estimation of nonlinear dynamical systems based on integrator theory
Authors: Peng Haipeng , Li Lixiang , Yang Yixian , Wang Cong
Published: September 2009

In this paper, a novel unknown parameter identifier of nonlinear dynamical systems is designed through the integrator theory, and the corresponding sufficient conditions for the existence of unknown parameter identifiers are presented. In order to illustrate the effectiveness of the proposed method, simulation results are given. The effects of system noise and measurement noise for the proposed method are discussed in detail. The comparative analysis between the proposed method based on integrator theory and the approach based on adaptive synchronization is also given.
Test of classical nucleation theory and mean first-passage time formalism on crystallization in the Lennard-Jones liquid
Authors: Lundrigan Sarah E. M. , Saika-Voivod Ivan
Published: September 2009

We perform molecular dynamics (MD) and Monte Carlo computer simulations to test the ability of the recently developed formalism of mean first-passage time (MFPT) [J. Wedekind, R. Strey, and D. Reguera, J. Chem. Phys. 126, 134103 (2007); J. Wedekind and D. Reguera, J. Phys. Chem. B 112, 11060 (2008)] to characterize crystal nucleation in the Lennard-Jones liquid. We find that the nucleation rate, critical embryo size, Zeldovich factor, attachment rate, and the nucleation barrier profile obtained from MFPT all compare very well to the same quantities calculated using other methods. Furthermore, we find that the nucleation rate obtained directly through MD closely matches the prediction of classical nucleation theory.
Contribution of water droplets to charge release by laser filaments in air
Authors: Henin Stefano , Petit Yannick , Kiselev Denis , Kasparian Jérôme , Wolf Jean-Pierre
Published: September 2009

We measured the electric charge release from single water microdroplets illuminated by ultrashort laser filaments in air. This charge is up to 600 times larger than from a comparable filament volume in air. In contrast, for atmospheric droplet concentrations and sizes, the volume-averaged overall droplet contribution to the charge is small as compared with that of the filaments along its whole propagation path.
Laser dynamic forming of functional materials laminated composites on patterned three-dimensional surfaces with applications on flexible microelectromechanical systems
Authors: Yu Cunjiang , Gao Huang , Yu Hongyu , Jiang Hanqing , Cheng Gary J.
Published: September 2009

Laser dynamic forming (LDF) is a three-dimensional (3D) forming technique, which utilizes laser to induce shock wave and shape the target thin films onto micro/nanoscale 3D surfaces. This technique has been used to form metals on 3D surfaces. This letter extends LDF to functional and brittle materials sandwiched by elastomeric polymers on patterned 3D surface. The elastomeric polymers absorb the shock energy and minimize the degradation of the functional materials. The patterned 3D surfaces control the plasticity in the structure and therefore retain the function of the structure. The performance was evaluated and mechanisms were studied.
Transition zone dynamics in combined isotachophoretic and electro-osmotic transport
Authors: Schönfeld Friedhelm , Goet Gabriele , Baier Tobias , Hardt Steffen
Published: September 2009

The present study focuses on the interplay of isotachophoresis (ITP) and electro-osmotic flow (EOF). While EOF is commonly suppressed in ITP applications, we investigate scenarios of the combination of both EOF and ITP. Experimental results of ITP/EOF experiments within cross-patterned polymer chips show characteristic deformations of fluorescent sample zones sandwiched between leading and trailing electrolytes. A changing curvature of the deformation is observed during ITP/EOF runs, but overall a well defined sample segment is maintained after a transport over a few centimeters. By means of numerical modeling we study the deformation attributed to the mismatch of EOF between leading and trailing electrolytes. The model results are found to qualitatively agree with our experimental findings. We introduce the ratio of the EOF velocities in the leading and trailing electrolyte, expressed via the respective mobilities, as a dimensionless parameter γ and show that in the case where electro-osmotically induced convection dominates over electromigration the deformation width scales as 1−γ. In particular, we find that the EOF-induced dispersion virtually vanishes for the case γ=1. Hence, in this particular case isotachophoretic self-sharpening and electro-osmotic pumping can be combined without any detrimental effects on sample transport even for large EOF velocities.
Combined electric field and stress-induced R-O phase transformation in [011]-poled Pb(Mg1/3Nb2/3)O3–(28–32)%PbTiO3 single crystals of [011¯]-length cut
Authors: Shanthi M. , Lim L. C.
Published: September 2009

The combined effects of applied electric field and axial compressive stress on the strain behavior of [011]-poled Pb(Mg1/3Nb2/3)O3–(28–32)%PbTiO3 [PMN-(28–32)%PT] single crystals of [011¯]-length cut have been investigated. For this crystal cut, the axial compressive stress has little effect on the R-O transformation field, the latter being >1.0 kV/mm for PMN-(28–30)%PT. This crystal cut is thus ideal for applications involving large electric field and axial compressive stress.
Multilayer barrier films comprising nitrogen spacers between free-standing barrier layers
Authors: Granstrom Jimmy , Villet Michael , Chatterjee Tirtha , Gerbec Jeffrey A. , Jerkunica Evan , Roy Anshuman
Published: September 2009

An encapsulation architecture for organic electronic devices utilizing nitrogen gas-phase spacers between free-standing barrier films is demonstrated. The nitrogen spacers act as sinks for permeating H2O and O2, delaying establishment of steady-state chemical potential gradients across the barriers and thereby reducing permeation rates. Water vapor transmission through nitrogen-spaced barriers was measured via the calcium optical transmission test. Substantial reductions in permeation rate were observed for a variety of barrier materials and configurations, suggesting a general and cost-effective approach for improving encapsulation performance. A low-cost polyethylene terephthalate film increases the calcium lifetime of a Cytop™-Kureha structure from 7000 to 12000 min.
Ordering of pentacene in organic thin film transistors induced by irradiation of infrared light
Authors: Wang C. H. , Chen S. W. , Hwang J.
Published: September 2009

The device performances of pentacene-based organic thin film transistors (OTFTs) were greatly improved by irradiation of infrared light. The field effect mobility and maximum drain current increase from 0.20±0.01 to 0.57±0.02 cm2/V s and 1.14×10−5 to 4.91×10−5 A, respectively. The (001) peak of the pentacene “thin film” phase increases in intensity by 4.5 times after infrared irradiation at 50 W for 2 h. Two types of crystal orientations, i.e., “crystal I” (2θ=5.91°) and “crystal II” (2θ=5.84°), coexist in the pentacene. The improvement of the characteristics of OTFTs is attributed to crystallization and crystal reorientation induced by infrared light.
Strong improvement in the photonic stop-band edge sharpness of a lithium niobate photonic crystal slab
Authors: Diziain S. , Harada S. , Salut R. , Muralt P. , Bernal M.-P.
Published: September 2009

We report on a photonic crystal (PhC) etched into a 380 nm thick lithium niobate (LN) thin film deposited on a MgO substrate by pulsed laser deposition. The transmission properties of this device were assessed by optical near-field measurements and compared to the transmission spectra of the same PhC drilled into bulk LN and calculated by a two dimensional finite-difference time domain method. We show a strong improvement in the transmission properties of the LN PhC by etching it into a thin layer rather than into a 500 μm thick wafer. This result appears to be very promising for applications based on LN tunable PhCs.
High-speed all-optical modulation of a standard quantum cascade laser by front facet illumination
Authors: Chen Gang , Bethea Clyde G. , Martini Rainer , Grant P. D. , Dudek R. , Liu H. C.
Published: September 2009

A simple experimental scheme to control intersubband lasing transition by optically induced nonresonant interband transition is presented, allowing for high-speed all-optical modulation of mid-infrared (MIR) quantum cascade laser (QCL). Illuminating the QCL front facet with 100 fs Ti:sapphire laser pulse, a fast modulation of a cw-MIR emission is observed with an estimated transient time of less than 81 ps, limited by instrument bandwidth, and a modulation depth of 18%. It has a great potential for high-speed modulation of high power QCL at room temperature.
Floating-gate memory based on an organic metal-insulator-semiconductor capacitor
Authors: William S. , Mabrook M. F. , Taylor D. M.
Published: September 2009

A floating gate memory element is described which incorporates an evaporated gold film embedded in the gate dielectric of a metal-insulator-semiconductor capacitor based on poly(3-hexylthiophene). On exceeding a critical amplitude in the voltage sweep, hysteresis is observed in the capacitance-voltage (C-V) and current-voltage (I-V) characteristics of the device. The anticlockwise hysteresis in C-V is consistent with strong electron trapping during the positive cycle but little hole trapping during the negative cycle. We argue that the clockwise hysteresis observed in the negative cycle of the I-V plot, arises from leakage of trapped holes through the underlying insulator to the control gate.
Some properties of the M3D-C1 form of the three-dimensional magnetohydrodynamics equations
Authors: Breslau J. , Ferraro N. , Jardin S.
Published: September 2009

A set of scalar variables and projection operators for the vector momentum and magnetic field evolution equations is presented that has several unique and desirable properties, making it a preferred system for solving the magnetohydrodynamic equations in a torus with a strong toroidal magnetic field. A “weak form” of these equations is derived that explicitly conserves energy and is suitable for a Galerkin finite element formulation provided the basis elements have C1 continuity. Systems of reduced equations are discussed, along with their energy conservation properties. An implicit time advance is presented that adds diagonally dominant self-adjoint energy terms to the mass matrix to obtain numerical stability.
Hysteretic bipolar resistive switching characteristics in TiO2/TiO2−x multilayer homojunctions
Authors: Do Young Ho , Kwak June Sik , Bae Yoon Cheol , Jung Kyooho , Im Hyunsik , Hong Jin Pyo
Published: September 2009

TiO 2 (oxygen rich, region 1)/TiO2−x (oxygen poor, region 2) multilayer homojunctions were studied as alternative resistive switching structures for both high and low resistance transitions. Stable bipolar resistive switching characteristics, including stable switching speeds (microseconds) and endurance behaviors, as well as long retention times (>104 s) were demonstrated. The nature of the resistive switching phenomenon in multilayer structures seems to be a combination of the conduction path and the redox reaction, resulting from the oxygen ions drifting between the oxygen rich and poor regions of the multilayer structures. A possible conduction sketch for bipolar switching behaviors is also discussed.
Fabrication of Cu2O/TiO2 nanotube heterojunction arrays and investigation of its photoelectrochemical behavior
Authors: Hou Y. , Li X. Y. , Zhao Q. D. , Quan X. , Chen G. H.
Published: September 2009

Cu 2 O / TiO 2 nanotube heterojunction arrays have been prepared by photoreduction depositing Cu2O nanoparticles on TiO2 nanotube arrays. The heterojunction arrays show uniformly distributed Cu2O nanoparticles, and high crystallinity of anatase and cubic from the TiO2 and Cu2O, respectively. The asymmetry of the current-voltage plot for the material reveals that a heterojunction has been formed between TiO2 and Cu2O. Enhanced charge separation efficiency and improved photoconversion capability are confirmed by electrochemical impedance spectroscopy and photocurrent measurement.
Capacitance switching in SiO2 thin film embedded with Ge nanocrystals caused by ultraviolet illumination
Authors: Yang M. , Chen T. P. , Ding L. , Liu Y. , Zhu F. R. , Fung S.
Published: September 2009

A structure of indium tin oxide/SiO2 embedded with Ge nanocrystal (nc-Ge)/p-Si substrate was fabricated. The capacitance of the structure can be switched to a high-capacitance or low-capacitance state by an ultraviolet (UV) illumination. The increase (or decrease) in the capacitance is accompanied with the decrease (or increase) in the oxide resistance. The capacitance switching is explained in terms of the UV illumination-induced charging and discharging in the nc-Ge.
Surface landing of microtubule nanotracks influenced by lithographically patterned channels
Authors: Lin Chih-Tin , Kao Ming-Tse , Meyhofer Edgar , Kurabayashi Katsuo
Published: September 2009

Microtubules, which serve as cellular structural components in nature, can be placed within a lithographically patterned channel as engineered nanoscale tracks for bionanotechnology applications. We study the landing behavior of microtubules upon their diffusion onto a kinesin-coated glass surface in the presence of the channel. The influence of channel geometry on the landing rate of microtubules is experimentally characterized using channels with varying width. Additionally, we develop a theoretical model to quantitatively analyze our data by accounting for geometrical constraints due to both the width and height of the channels against the diffusion of the landing microtubules.
Generation of multicycle terahertz phonon-polariton waves in a planar waveguide by tilted optical pulse fronts
Authors: Lin Kung-Hsuan , Werley Christopher A. , Nelson Keith A.
Published: September 2009

We demonstrate generation of frequency-tunable, multicycle terahertz phonon-polariton waves in a LiNbO3 slab waveguide. Because the waveguide modes show considerable phase-velocity dispersion, we are able to enhance frequency-selected narrowband terahertz waves by using femtosecond optical pulses whose intensity fronts are tilted at angles that meet the appropriate noncollinear phase-matching conditions. The pump light is spread across a large area of the crystalline waveguide within which coherent terahertz wave generation occurs, averting material damage, while yielding peak-to-peak terahertz field amplitudes in the waveguide of 50 kV/cm.
Tunable in situ growth of porous cubic silicon carbide thin films via methyltrichlorosilane-based chemical vapor deposition
Authors: Lien Wei-Cheng , Ferralis Nicola , Pisano Albert P. , Carraro Carlo , Maboudian Roya
Published: September 2009

The growth of cubic silicon carbide films with tunable porosity is demonstrated on Si(100) using a single precursor, methyltrichlorosilane, chemical vapor deposition process in the temperature range of 950–1200 °C. The pore size varies in the range from 250 nm to 2 μm and it is controlled by the growth temperature and the details of hydrogen introduction during substrate heating stage. It is proposed that silicon outdiffusion from substrate combined with hydrogen chloride production and adsorption on the surface at high temperature may be responsible for the porous films thus produced.
The origins of ferromagnetism in Co-doped ZnO single crystalline films: From bound magnetic polaron to free carrier-mediated exchange interaction
Authors: Lu Z. L. , Hsu H. S. , Tzeng Y. H. , Zhang F. M. , Du Y. W. , Huang J. C. A.
Published: September 2009

High-quality Co-doped ZnO single crystalline films with a wide range of carrier concentration and good reproducibility have been grown by molecular beam epitaxy. After the systematic studies of the magnetic and transport properties of the films, we suggest that there are two distinct ferromagnetic mechanisms in different conductivity regimes. In the insulating regime, carriers tend to be localized, favoring the formation of bound magnetic polarons, which leads to ferromagnetism. In the metallic regime, however, most carriers are weakly localized and the free carrier-mediated exchange is dominant. Our experimental observations are well consistent with the recent theoretical description of magnetism in Co-doped ZnO and helpful for understanding the ferromagnetic mechanism in oxide-based diluted magnetic semiconductors.
Low-voltage operation of n-type organic field-effect transistors with ionic liquid
Authors: Uemura T. , Yamagishi M. , Ono S. , Takeya J.
Published: September 2009

High performance n-type organic field-effect transistors are developed to achieve high transconductance and low-threshold voltage using ionic-liquid electrolyte for intense electrostatic gating. Tetracyanoquinodimethane single crystals and C60 thin films are interfaced with ionic liquid of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide known for its low viscosity and high ionic conductivity, so that high-density electrons are rapidly accumulated in the semiconductor surfaces with the application of minimum gate voltages, forming 1-nm thick electric double layers to concentrate electric field as high as 1 MV/cm. The C60 transistor shows the highest normalized transconductance among reported n-type organic transistors, together with minimum threshold voltage.
Active control of surface plasmon polaritons by optical isomerization of an azobenzene polymer film
Authors: Zhang D. G. , Yuan X.-C. , Bouhelier A. , Yuan G. H. , Wang P. , Ming H.
Published: September 2009

Active control of surface plasmon polaritons (SPPs) by optical isomerization of an azobenzene polymer film is proposed and demonstrated in this letter. A tightly focused 532 nm laser beam was used to change the wave number of the SPPs and a separate unpolarized light source was employed to erase the change, forming one cycle of the control. The largest change of the SPPs wave number obtained in the experiments is about 0.0382K0 in the case of 54 nm thickness azo-polymer film. Validity of this method is confirmed by consistence between theoretical and experimental results.
Compositional influence on sol-gel-derived amorphous oxide semiconductor thin film transistors
Authors: Kim Dongjo , Koo Chang Young , Song Keunkyu , Jeong Youngmin , Moon Jooho
Published: September 2009

We investigated the influence of the chemical compositions of gallium and indium cations on the performance of sol-gel-derived amorphous gallium indium zinc oxide (a-GIZO)-based thin film transistors (TFTs). A systematic compositional study allowed us to understand the solution-processed a-GIZO TFTs. We generated a compositional ternary diagram from which we could predict electrical parameters such as saturation mobility, threshold voltage, and the on/off current ratio as the constituent compositions varied. This diagram can be utilized for tailoring solution-processed amorphous oxide TFTs for specific applications.