bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unilaterally connected large digraphs and generalized cycles
Authors: Gómez José , Canale Eduardo A. , Muñoz Xavier 
Published: October 2004

AbstractLower and upper bounds on the order of digraphs and generalized p‐cycles with a specified maximum degree and unilateral diameter are given for generic values of the parameters. Infinite families of digraphs attaining the bounds asymptotically or even exactly are presented. In particular, optimal results are proved for bipartite digraphs (p = 2) and digraphs with unilateral diameter 3. © 2003 Wiley Periodicals, Inc.
On the power of BFS to determine a graph's diameter
Authors: Corneil Derek G. , Dragan Feodor F. , Köhler Ekkehard 
Published: October 2004

AbstractRecently, considerable effort has been spent on showing that Lexicographic Breadth First Search (LBFS) can be used to determine a tight bound on the diameter of graphs from various restricted classes. In this paper, we show that, in some cases, the full power of LBFS is not required and that other variations of Breadth First Search (BFS) suffice. The restricted graph classes that are amenable to this approach all have a small constant upper bound on the maximum‐sized cycle that may appear as an induced subgraph. We show that, on graphs that have no induced cycle of size greater thank, BFS finds an estimate of the diameter that is no worse than diam(G) − ⌊k/2⌋. © 2003 Wiley Periodicals, Inc.
Loosely woven fabric model with viscoelastic crimped fibres for ballistic impact simulations
Authors: Ivanov Ivelin , Tabiei Ala 
Published: October 2004

AbstractA computational micro‐mechanical material model of loosely woven fabric for non‐linear finite element impact simulations is presented in this work. The model is a mechanism incorporating the crimping of the fibres as well as the trellizing. The equilibrium of the mechanism allows the straightening of the fibres depending on the fibre tension. The contact force at the fibre crossover point determines the rotational friction dissipating a part of the impact energy. The stress–strain relationship is viscoelastic based on a three‐element model. The failure of the fibres is strain rate dependent. The model is implemented as user defined subroutine in the transient finite element code LS‐DYNA. The ballistic impact simulations with the model are in good agreement with the experimental results. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of poly(epoxy‐imide) crosslinked networks
Authors: Yang Seung‐Jin , Lee Choonkeun , Jang Wonbong , Kwon Jinuk , Sundar Saimani , Han Haksoo 
Published: October 2004

AbstractPoly(epoxy imide)s were prepared by a reaction between a hydroxyl‐group‐containing soluble copolyimide and commercial epoxy resins at 220 °C for 2 h. Poly(epoxy imide) thin films exhibited higher thermal stability and lower dielectric constants than a commercial flip‐chip package material (U300). The thermal stabilities of the poly(epoxy imide)s were 1.4–2.0 times higher than that of U300. The thermal stability increased with increasing crosslink density and with decreasing bulky CF3 groups (which were easily decomposable). The dielectric constants of the poly(epoxy imide)s were 1.1–1.3 times lower than that of U300, and this is highly desirable for the microelectronic packaging industry. The dielectric constant dramatically decreased when bulky CF3 groups were added and when the functionalities of epoxy resins decreased. The residual stresses, slopes in the cooling curves, and glass‐transition temperatures of the poly(epoxy imide)s were measured with a thin‐film stress analyzer. Low residual stresses and slopes in the cooling curves were achieved with a higher crosslink density. However, in the presence of bulky CF3 groups, the copolyimide backbone structure did not affect the residual stress values. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4293–4302, 2004
Sorption and desorption of flumioxazin to soil, clay minerals and ion‐exchange resin
Authors: Ferrell Jason A , Vencill William K , Xia Kang , Grey Timothy L 
Published: October 2004

AbstractFlumioxazin adsorption kinetics were described using a Greenville sandy clay loam soil. Adsorption kinetics experiments showed that 72% of total herbicide was absorbed after 1 h of continuous shaking and continued to increase to 78% after 72 h. Flumioxazin adsorption was then tested on seven agriculturally important soils throughout the southern USA. Adsorption isotherms for all soils had Kf (Freundlich distribution coefficient) values that ranged from 8.8 to 0.4, with many near 1.5. Soil organic matter content was the parameter most highly correlated with flumioxazin adsorption (r2 = 0.95, P < 0.001). Sorption to clay minerals had Kf values ranging from 50 for bentonite to 4.7 for kaolinite. However, normalizing Kf for sorbent surface area revealed that aluminum hydroxide (gibbsite) possessed the greatest flumioxazin sorption per unit area. Sorption to anionic exchange resin (Kf 676) was greater than cationic exchange resin (Kf 42). Molecular model calculations were performed to elucidate why sorption was greater to anionic exchangers. These calculations indicated that a region of dense electronegativity exists on the 3‐dione moiety of the molecule. This would lead to greater flumioxazin sorption by positively charged surface sites. Desorption isotherms from soil exhibited no effect of hysteresis. Desorption from clay minerals was very rapid and flumioxazin in solution was undetectable after three desorption steps. From these data it was concluded that flumioxazin can become readily available in soil solution with increase in soil water content. Copyright © 2004 Society of Chemical Industry
Pressure tuning of localized and extended vibrational modes in Si:O
Authors: McCluskey M. D. 
Published: October 2004

AbstractInterstitial oxygen in silicon (Si:O) is a model system for the study of vibrational modes in semiconductors. Hydrostatic pressure has been used to probe the vibrational properties of this defect. In this paper, the results of infrared (IR) spectroscopy experiments on Si:16O and Si:18O are reviewed. As pressure is applied, the oxygen atom buckles outward. This structural change results in a qualitative change in low‐frequency vibrational motion in the [111] plane, as the system transforms from a harmonic oscillator to a rotor. A particularly interesting phenomenon occurs when the Si:18O local vibrational mode (LVM) approaches the two‐phonon continuum. First, the LVM exhibits an avoided crossing with certain combination modes of the defect. Second, when the LVM enters the two‐phonon continuum, the linewidth abruptly broadens, due to a decrease in the lifetime. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Competitive effects on the high‐pressure phase diagram of manganites
Authors: Postorino P. , Sacchetti A. , Capone M. , Dore P. 
Published: October 2004

AbstractRecent infrared absorption measurements performed at different pressures and temperatures on the La0.75Ca0.25MnO3 manganite provided the insulator‐to‐metal transition temperature TIM(P), i.e. the P–T phase diagram of the manganite. We report an extended data analysis, by considering in detail pressure and temperature dependence of the observed IR active phonon and of the absorption spectral weights N*. The phonon pressure‐dependence, consistently with the P–T phase diagram, indicates the onset of a new localizing interaction above P* = 6–7 GPa. Finally a simple theoretical model will be employed to give a qualitative explanation of the observed high‐pressure behavior and to suggest the relevance of the charge‐localizing super‐exchange magnetic interaction in the very high‐pressure regime. Within this framework the asymptotic regime at high pressure is ascribed to the competition between the magnetic super‐ and double‐exchange interactions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Amplified spontaneous emission measurements in a diamond anvil cell: A tool to investigate laser diode gain under high pressure
Authors: Patel D. , Xu L. F. , Pownall R. , Anton O. , Menoni C. S. 
Published: October 2004

AbstractIn this work we report on results of amplified spontaneous emission measurements on InGaAsP laser diodes from which gain spectra at different biases and as a function of hydrostratic pressure were obtained. From the analysis of the gain spectra, peak net modal gain, internal losses and quasi‐Fermi energy separation are determined. Knowledge of the latter provides a pathway to determine the injected carrier density and henceforth to calculate the rate of change of the peak gain with carrier density (dg/dN), the transparency carrier density and their pressure behaviour. The evolution of these parameters with pressure allows us to develop a comprehensive picture of the behaviour of the laser threshold current of 1.3 μm communication lasers. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman modes in oligophenyls under hydrostatic pressure
Authors: Martin C. M. , Cai Q. , Guha S. , Graupner W. , Chandrasekhar M. , Chandrasekhar H. R. 
Published: October 2004

AbstractWe present a low temperature study of the Raman modes in three oligo(para‐phenylene) materials (p‐terphenyl, 3P; p‐quaterphenyl, 4P; and p‐hexaphenyl, 6P) under hydrostatic pressure up to 80 kbar. The 1220 cm–1 (C–H in plane bend), 1280 cm–1 (C–C interring stretch), 1600 cm–1 (aromatic C–C on‐ring stretch) and 1610 cm–1 (combination mode of 610 cm–1 and 990 cm–1) modes provide indicators of planarization in their frequency and intensity behaviors. In this comparative study of 3P, 4P, and 6P, the most remarkable feature is the clearly defined change in the slope of the 1220 cm–1 in‐plane bending mode upon planarization. In contrast, modes in the 1600 cm–1 region do not have as clear a two‐slope behavior; however, a more sensitive measure of planarization is the frequency difference between the 1610 cm–1 and the 1600 cm–1 modes, which exhibits a distinct drop before planarization, and a gradual increase thereafter. The resonance conditions that are responsible for the 1610 cm–1 mode make the two‐slope behavior less pronounced as compared to the 1280–1220 pair of modes. The intensity of the Raman modes from all three oligophenyls also indicate planarization: the intensity of the 1280 cm–1 mode decreases sharply relative to the 1220 cm–1 mode until the molecule planarizes, and increases slowly thereafter. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrostatic pressure effects on the donor impurity‐related photoionization cross‐section in cylindrical‐shaped GaAs/GaAlAs quantum well wires
Authors: Correa J. D. , Cepeda‐Giraldo O. , Porras‐Montenegro N. , Duque C. A. 
Published: October 2004

AbstractUsing a variational method the binding energy has been calculated for a shallow donor impurity and the donor‐related photoionization cross‐section in 1D and 0D GaAs low‐dimensional systems. The dependence on the binding energy and the photoionization cross‐section for a hydrogenic donor impurity in the finite potential model are discussed and the results are presented as a function of the radius, polarization of the photon, applied hydrostatic pressure, and photon energy. The calculations for the pressure effects are performed both in the direct and indirect GaAs gap regime. Calculations are presented for an on‐axis (on‐center) impurity in the wire (in the dot). (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light scattering of double wall carbon nanotubes under hydrostatic pressure: pressure effects on the internal and external tubes
Authors: Puech P. , Hubel H. , Dunstan D. J. , Bassil A. , Bacsa R. , Peigney A. , Flahaut E. , Laurent C. , Bacsa W. S. 
Published: October 2004

AbstractWe report high‐pressure Raman light scattering studies up to 10 GPa on double walled carbon nanotubes using two pressure transmitting media. In alcohol, a clear splitting of the G band is observed up to 10 GPa. This splitting is evidence for both discontinuous tangential stress and continuous radial stress. A structural distortion seems to be present at 3 GPa, revealed by a spectroscopic signature at 1480 cm–1. With argon as the pressure transmitting medium, the nanotubes bundles show a transition at 6 GPa which corresponds to a collapse to a flattened structure and removes the splitting. The comparison of the pressure coefficients before the transition for the two pressure transmitting media shows that the ratio of the two coefficients associated with internal and external tubes, is the same but the absolute values are different. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure dependence of 2D hole mobility in thermoactivated photoconductivity effect observed in p‐GaAs/Al0.5Ga0.5As heterostructures
Authors: Berman I. V. , Bogdanov E. V. , Ilievsky A. A. , Minina N. Ya. , Kraak W. 
Published: October 2004

AbstractThe temperature dependence of the 2D hole mobility in p‐GaAs/Al0.5Ga0.5As heterostructures has been investigated in dark and illuminated with red light states under uniaxial compression up to 3.4 kbar in the temperature interval 1.5–20 K. From numerical calculations it has been shown that the decrease of the 2D hole mobility below 5.5 K, where the recently observed thermoactivated negative photoconductivity takes place, may be well described by scattering on ionized deep donor‐like traps located in Al0.5Ga0.5As in the vicinity of a heterointerface. According to the calculations, these traps are distributed in the spacer at distances of 7–48 nm from the heterointerface and their contribution to 2D hole scattering strongly increases under uniaxial compression. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical properties and structural phase transitions of lead‐halide based inorganic–organic 3D and 2D perovskite semiconductors under high pressure
Authors: Matsuishi K. , Ishihara T. , Onari S. , Chang Y. H. , Park C. H. 
Published: October 2004

AbstractOptical absorption, photoluminescence and Raman scattering of lead‐halide based inorganic–organic perovskite semiconductors were measured under quasi‐hydrostatic pressure at room temperature. For the 3D perovskite semiconductor, (CH3NH3)PbBr3, the free exciton photoluminescence band exhibits red‐shifts with pressure, and jumps to a higher energy by 0.07 eV at 0.8 GPa, which is associated with a phase transition from a cubic to an orthorhombic structure confirmed by Raman scattering. Above the phase transition pressure, the exciton band shows blue‐shifts with further increasing pressure, and eventually disappears above 4.7 GPa. The results are compared with those for the 2D perovskite semiconductor, (C4H9NH3)2PbI4. First principles pseudopotential calculations were performed to investigate changes in octahedral distortion and electronic band structures with pressure. The calculations have explained the origins of the intriguing changes in the electronic states with pressure in view of bonding characters between atomic orbitals in octahedra. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitation and pressure effects on low temperature photoluminescence from GaAs/GaInP heterostructures
Authors: Nagata Atsushi , Kobayashi Toshihiko , Prins Andrew D. , Homma Yasuhiro , Uchida Kazuo , Nakahara Jun‐ichiro 
Published: October 2004

AbstractWe report for the first time the results of a study of 11 K photoluminescence (PL) measurements of metal‐organic vapor phase epitaxy grown GaAs/GaInP quantum wells at pressures up to ∼5 GPa and examine the effects of laser excitation energy and intensity. The use of low temperature allows us to study the true nature of a peak at ∼1.46 eV, which dominates instead of the GaAs QW emission, even at very low excitation intensities to pressures well above the Γ–X crossover in GaInP. Our results suggest that the ∼1.46 eV emission is a spatially indirect transition of electrons and holes separated at the interface in a type‐II band alignment. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure Raman study of BaMoO4
Authors: Christofilos D. , Arvanitidis J. , Kampasakali E. , Papagelis K. , Ves S. , Kourouklis G. A. 
Published: October 2004

AbstractThe structural stability of polycrystalline BaMoO4 under hydrostatic pressure has been investigated by means of Raman spectroscopy up to 8 GPa. Raman spectra reveal a pressure induced phase transition at ∼5.8 GPa. Upon pressure release the structure reverts to its ambient pressure scheelite (CaWO4) structure with no observable hysteresis. The large number of Raman active modes of the high pressure phase suggests either an increase of the size of the unit cell and/or a non‐centrosymmetric structure leading to the activation of the ungerade modes of the scheelite structure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Carrier recombination processes in 1.3 μm and 1.5 μm InGaAs(P)‐based lasers at cryogenic temperatures and high pressures
Authors: Sweeney S. J. , Jin S. R. , Ahmad C. N. , Adams A. R. , Murdin B. N. 
Published: October 2004

AbstractWe describe measurements of the threshold current of 1.3 μm and 1.5 μm InGaAs(P)‐based quantum‐well lasers measured at cryogenic temperatures and at high pressures. At low temperatures (∼100 K), we find that the threshold current of the devices increases with increasing pressure consistent with the calculated pressure variation of the radiative current. This is in sharp contrast with their pressure dependence at room temperature (RT), where the threshold current decreases with increasing pressure due to the decrease in importance of Auger recombination. These low‐temperature, high‐pressure results agree well with previous temperature dependence measurements on the same devices, which show a transition from radiative to non‐radiative Auger recombination dominated behaviour as the laser temperature is increased from ∼100 K to room temperature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure dependence of optical transitions in semiconducting single‐walled carbon nanotubes
Authors: Shan W. , Wu J. , Walukiewicz W. , Ager J. W. , Yu K. M. , Haller E. E. , Kissell K. , Bachilo S. M. , Weisman R. B. , Smalley R. E. 
Published: October 2004

AbstractThe effects of applied hydrostatic pressure on the optical transitions in semiconducting single‐walled carbon nanotubes with different diameters and chiralities have been studied using optical absorption and photoluminescence spectroscopy. The excitonic transitions associated with the band‐gap (the first van Hove transition) energies in the carbon nanotubes are found to shift to lower energy at a rate depending on nanotube structure. The excitonic transitions between the first excited confinement states (the second van Hove transitions) are found to be much less sensitive to the applied hydrostatic pressure. All nanotubes show a dependence on their chirality in terms of pressure coefficient of the band‐gap energy, with the larger‐diameter nanotubes exhibiting a higher sensitivity of the band‐gap energy to hydrostatic pressure. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Bayesian operationalization of the resource‐based view
Authors: Hansen Mark H. , Perry Lee T. , Reese C. Shane 
Published: October 2004

AbstractThis paper argues that the gap between the theoretical utility and the practical utility of the resource‐based view (RBV) may be narrowed by operationalizing the theory more consistently with Penrose's original framework. The operationalization proposed here is a twofold approach. First, the RBV may be enhanced by the explicit recognition of Penrose's two classes of resources, namely, administrative resources and productive resources. This distinction suggests a focus on the administrative decisions of managers that lead to economic performance. Second, we argue that the RBV is a theory about extraordinary performers or outliers—not averages. Therefore, the statistical methods used in applying the theory must account for individual firm differences, and not be based on means, which statistically neutralize firm differences. We propose a novel Bayesian hierarchical methodology to examine the relationship between administrative decisions and economic performance over time. We develop and explain a measure of competitive advantage that goes beyond comparisons of economic performance. This Bayesian methodology allows us to make meaningful probability statements about specific, individual firms and the effects of the administrative decisions examined in this study. Copyright © 2004 John Wiley & Sons, Ltd.
Neutron Scattering as a Powerful Tool in Solid State Chemistry. Examples from the Investigations in Crystal Structures and Properties of Metal Hydrogen and Metal Chalcogen Compounds
Authors: Auffermann Gudrun , Müller Paul , Bronger Welf 
Published: October 2004

AbstractNeutron scattering experiments play a key role in the investigation in crystal structures and properties of solid compounds which is demonstrated with examples from the compound series AxMyXz (A ≙ alkali metal, M ≙ transition metal and X ≙ H, S or Se). Measurements on powdered samples provide as well the hydrogen positions within the crystal structures of ternary hydrides by using the analogous deuterium compounds as the lithium positions in the compounds with A ≙ Li. Ferromagnetic and antiferromagnetic arrangements are investigated by neutron diffraction which lead to the determination of the magnetic moments of transition metal atoms providing information about chemical bonding. Finally, it is demonstrated that inelastic neutron scattering is an independent method used in a complementary way to infrared or Raman spectroscopy, and, due to the interactions of neutrons with the magnetic states of transition metal atoms, to susceptibility or magnetisation.
About Trihalides with TiI3 Chain Structure: Proof of Pair Forming of Cations in β‐RuCl3 and RuBr3 by Temperature Dependent Single Crystal X‐ray Analyses
Authors: Hillebrecht H. , Ludwig Th. , Thiele G. 
Published: October 2004

AbstractSingle‐crystal X‐ray studies on β‐RuCl3 and RuBr3 at different temperatures verified, that both compounds are dimorphic and show reversible phase transitions at 206 K resp. 384 K. In the HT‐forms the Aristo‐type of the hexagonal TiI3‐structure with space group P63/m c m (Z = 2, β‐RuCl3 at 293(2) K: a = 6.121(2) Å, c =5.655(2) Å, RuBr3 at 423(3) K: 6.5215(12) Å, c= 5.8851(13) Å) has been found, in the LT‐forms the RuBr3‐type structure, an orthorhombic distorted variant with space group Pmmn (Z = 4, β‐RuCl3 at 170(3) K: a= 10.576(2) Å, b = 5.634(1) Å, c = 6.106(1) Å, RuBr3 at 293(2) K: a = 11.2561(16) Å, b = 5.8725(12) Å, c = 6.4987(9) Å). A hexagonal closest packing of X‐ anions forms the basis of an arrangement of infinite chains with face‐connected [RuX6/2] octahedra. While in the chains of the hexagonal HT‐forms the Ru‐Ru‐distances are identical (d(Ru‐Ru) = 2.8275(10) Å for β‐RuCl3, d(Ru‐Ru) = 2.9425(6)Å for RuBr3), in the orthorhombic structures the chains are distorted through pairing of the ruthenium(III) atoms (d(Ru‐Ru) = 2.6328(14) Å / 3.0010(15) Å for β‐RuCl3 at 170(3) K, d(Ru‐Ru) = 2.765(1) Å / 3.108(1) Å for RuBr3 at 293(2) K).The hexagonal metric with a/c= √3 holds also for the orthorhombic LT‐forms. Large crystals and the final products of the phase transition from HT‐ to LT‐forms are pseudomerohedral twins of three twin domains with nearly equal amounts complicating proof and analysis of the LT‐forms.