bluuebunny/crossref_metadata_2025 huggingface dataset:
Immunoadsorption may provide a cost‐effective approach to management of patients with inhibitors to FVIII
Authors: Freedman John , Rand Margaret L. , Russell Olive , Davis Carole , Cheatley Patricia L. , Blanchette Victor , Bernadette Garvey M.
Published: October 2003

BACKGROUND:  Immunoadsorption of plasma with Staphylococcal protein A removes immunoglobulins and immune complexes; hence, it should effectively remove inhibitors to FVIII in acquired or congenital hemophilia. The procedure may be cost effective, given the expense of therapies used to treat patients with inhibitors, particularly in an acute setting.

STUDY DESIGN AND METHODS:  Three patients with inhibitors to FVIII were treated with the Excorim Immunosorba system (two columns used in tandem). Costs for immunoadsorption and for other therapeutic products administered to the patients were calculated.

RESULTS:  Two patients had acquired hemophilia and severe bleeding associated with low levels of circulating FVIII and high levels of inhibitors to FVIII. They failed to achieve a satisfactory response to management with immunosuppression, pFVIII, recombinant FVIIa or IVIG but responded rapidly, with long‐term benefit, to immunoadsorption therapy. The third patient had congenital hemophilia and immunoadsorption was effective in reducing his inhibitor level, allowing him to undergo immune tolerance therapy. Costs of treatment before immunoadsorption were markedly higher than those associated with the immunoadsorption procedures (i.e., >Can$350,000 and >Can$1,000,000 vs. <$20,000).

CONCLUSION:  Immunoadsorption appears to be an effective and cost‐effective alternative in the management of patients with inhibitors to FVIII.
Structural evolution and dielectric relaxation behavior of electron-irradiated poly(vinylidene fluoride–trifluoroethylene) 80/20 mol % copolymers
Authors: Guo S. S. , Lau S. T. , Chan H. L. W. , Zhao X.-Z. , Choy C. L.
Published: October 2003

The effect of high-energy electron irradiation on poly(vinylidene fluoride-trifluoroethylene) 80/20 mol % copolymers has been studied in a broad dose ranging from 0 to 120 Mrad. It was found that the copolymers transformed from a normal ferroelectric to a relaxor ferroelectric phase (RFE) at high electron doses. For copolymers irradiated at the dose above 90 Mrad, they exhibited typical dielectric behavior of RFE, e.g., whose dielectric constant peaks show strong frequency dispersion. X-ray diffraction patterns showed that the irradiation induced a coexistence of the polar and nonpolar phase in the crystalline regions, leading to nanosized coherent regions in the irradiated copolymer films. Differential scanning calorimetery and polarization hysteresis loops also revealed the reduction in the crystallinity and stability of the ferroelectric state, reflecting significant changes in the ferroelectric-to-paraelectric phase transition due to the effect of high-energy electron irradiation.
Intermediate band solar cell with many bands: Ideal performance
Authors: Brown Andrew S. , Green Martin A.
Published: October 2003

When the intermediate band solar cell (IBSC) absorbs sunlight, electrons are excited not only between the valence and conduction bands of the semiconductor material constituting the cell, but also between these bands and one or more additional bands that lie within the normally forbidden band gap of the material. Therefore, this device has the potential to reach high conversion efficiencies by increasing the photogenerated current (due to these multiple step excitations) without reducing the open-circuit voltage. In this article, a general method of describing the operation of the IBSC with N bands is presented for the cases where both the valence and conduction bands are unrestricted and restricted in their width. It is found that for the restricted IBSC, all of the intermediate bandwidths must be zero to satisfy the applied constraints. The efficiency for the unrestricted IBSC device under maximally concentrated black-body radiation with an infinite number of bands is estimated to be 85.0%. Under an air mass (AM) of 1.5 global radiation, an efficiency of 53.5% for the five-band IBSC is found to be the upper limit. Finally, the IBSC is found to be robust to changes in the AM.
Strain determination in silicon microstructures by combined convergent beam electron diffraction, process simulation, and micro-Raman spectroscopy
Authors: Senez Vincent , Armigliato Aldo , De Wolf Ingrid , Carnevale Gianpietro , Balboni Roberto , Frabboni Stefano , Benedetti Alessandro
Published: October 2003

Test structures consisting of shallow trench isolation (STI) structures are fabricated using advanced silicon (Si) technology. Different process parameters and geometrical features are implemented to investigate the residual mechanical stress in the structures. A technology computer aided design homemade tool, IMPACT, is upgraded and optimized to yield strain fields in deep submicron complementary metal–oxide–semiconductor devices. Residual strain in the silicon substrate is measured with micro-Raman spectroscopy (μ-RS) and/or convergent beam electron diffraction (CBED) for large (25 μm) and medium size (2 μm), while only CBED is used for deep submicron STI (0.22 μm). We propose a methodology combining CBED and technology computer aided design (TCAD) with μ-RS to assess the accuracy of the CBED measurements and TCAD calculations on the widest structures. The method is extended to measure (by CBED) and calculate (by TCAD) the strain tensor in the smallest structures, out of the reach of the μ-RS technique. The capability of determining, by both measurement and calculation, the strain field distribution in the active regions of deep submicron devices is demonstrated. In particular, it is found that for these structures an elastoplastic model for Si relaxation must be assumed.
Comment on “Measurement of the ion drag force on falling dust particles and its relation to the void formation in complex (dusty) plasmas” [Phys. Plasmas 10, 1278 (2003)]
Authors: Khrapak S. A. , Ivlev A. V. , Morfill G. E. , Thomas H. M. , Zhdanov S. K. , Konopka U. , Thoma M. H. , Quinn R. A.
Published: October 2003

It is shown that the quantitative interpretation of recent experiments to determine the ion drag force in complex (dusty) plasmas [C. Zafiu, A. Melzer, and A. Piel, Phys. Plasmas 9, 4794 (2002); 10, 1278 (2003)] is not correct. A comparison of different models of the ion drag force is carried out to illustrate the complexity of this issue and to highlight the current level of the research.
Interacting squares in arbitrary external field
Authors: Tutschka Christian
Published: October 2003

A model of a many-body system composed of squares with contact pair interactions in an arbitrary external field is presented. The formulation uses a mapping of the system onto polydisperse hard core mixtures. On the polydisperse level then, a simplified Hamiltonian function is specified. This assumption together with a further one about the global free energy functional for the pure hard core part of the idealized mixture make the model solvable. It is expected to hold for high temperatures, low densities, or low temperatures. The validity of the method of construction in the latter case is illustrated by a further application to a corresponding lattice system, for which exact results to compare with are readily available when the temperature is sufficiently low.
Interpolating semiconductor alloy parameters: Application to quaternary III–V band gaps
Authors: Donati G. P. , Kaspi R. , Malloy K. J.
Published: October 2003

We present a rationalized biquadratic interpolation algorithm for calculating quaternary semiconductor parameters and apply it to determine the band gaps of AlGaInAs, AlGaInP, AlInAsSb, GaInPAs, and GaInAsSb over complete compositional ranges. Extension to include bicubic corrections and quinary alloys are discussed. The band gaps of lattice-matched AlGaInAsSb and AlGaInPAs are reported.
Energy-dependent kinetic model of photon absorption by superconducting tunnel junctions
Authors: Brammertz G. , Kozorezov A. G. , Wigmore J. K. , den Hartog R. , Verhoeve P. , Martin D. , Peacock A. , Golubov A. A. , Rogalla H.
Published: October 2003

We describe a model for photon absorption by superconducting tunnel junctions in which the full energy dependence of all the quasiparticle dynamic processes is included. The model supersedes the well-known Rothwarf–Taylor approach, which becomes inadequate for a description of the small gap structures that are currently being developed for improved detector resolution and responsivity. In these junctions relaxation of excited quasiparticles is intrinsically slow so that the energy distribution remains very broad throughout the whole detection process. By solving the energy-dependent kinetic equations describing the distributions, we are able to model the temporal and spectral evolution of the distribution of quasiparticles initially generated in the photoabsorption process. Good agreement is obtained between the theory and experiment.
Localized-density-matrix implementation of time-dependent density-functional theory
Authors: Yam Chi Yung , Yokojima Satoshi , Chen GuanHua
Published: October 2003

A linear-scaling first-principles quantum mechanical method is developed to evaluate the optical responses of large molecular systems. Instead of a many-body wave function, the equation of motion is solved for the reduced single-electron density matrix in the time domain. The locality of the reduced single-electron density matrix is utilized to ensure that computational time scales linearly with system size. The two-electron Coulomb integrals are evaluated with the fast multipole method, and the calculation of exchange-correlation quadratures utilizes the locality of an exchange-correlation functional and the integral prescreening technique. As an illustration, the resulting time-dependent density-functional theory is used to calculate the absorption spectra of polyacetylene oligomers and linear alkanes. The linear-scaling of computational time versus the system size is clearly demonstrated.
Relaxation dynamics of charge carriers in mixed alkali fluoride glasses
Authors: Ghosh S. , Ghosh A.
Published: October 2003

We have reported the relaxation dynamics of charge carriers in mixed alkali fluoride glasses of compositions 50ZrF4–10BaF2–2YF3–3AlF3–(35−x)LiF–xNaF; where 0⩽x⩽35. We have analyzed the relaxation data for these mixed alkali glasses, taken in the frequency range from 10 Hz to 2 MHz and in the temperature range from room temperature to just below the glass transition temperature, in the framework of the electric modulus formalism. We have observed the mixed alkali effect in the conductivity and the conductivity relaxation for these mixed alkali fluoride glasses, where anions also participate in the diffusion processes in addition to cations unlike mixed alkali oxide glasses. We have also observed mixed alkali effect in decoupling index. The scaling property of the modulus spectra of these mixed alkali glasses shows that the relaxation in fluoride glasses is independent of the temperature, but is dependent on composition.
Theory of the blocking temperature in polycrystalline exchange biased bilayers based on a thermal fluctuation model
Authors: Xi Haiwen , White Robert M.
Published: October 2003

It is well known that the exchange bias between an antiferromagnet (AF) and a ferromagnet (FM) vanishes at a temperature called the “blocking” temperature. The blocking temperature of polycrystalline exchange biased bilayers is theoretically studied on the basis of a thermal fluctuation model, from which an analytic expression for the blocking temperature as a function of the AF thickness and the AF grain size is obtained for a thin AF layer. This study also gives a quantitative understanding of the relationship of the blocking temperature to the Néel temperature of the AF and the Curie temperature of the FM.
Transverse depth-profilometric hardness photothermal phase imaging of heat treated steels
Authors: Liu Yue , Baddour Natalie , Mandelis Andreas
Published: October 2003

A method to image near-surface hardness profiles of heat-treated case-hardened steels using laser infrared photothermal radiometric phase imaging is described. It is shown that thermophysical and mechanical transverse inhomogeneity profiles in industrial case hardened steel samples are well correlated. Phase surface scanning imaging leads to a practical criterion for assessing transverse hardness homogeneity. A simple method based on phase imaging is proposed as a quantitative criterion to determine which steel samples should be rejected for thermal-wave depth-profilometric reconstruction of thermal diffusivity or conductivity.
Using force fields methods for locating transition structures
Authors: Jensen Frank
Published: October 2003

A previously proposed strategy of using force field methods for generating approximations to the geometry of transition structures is extended to also estimating an approximate Hessian matrix. These two components allow an automated method for locating first order saddle points, which is an essential requisite for studying chemical reactions of systems with many degrees of freedom. The efficiency of using an approximate force field Hessian matrix for initiating the geometry optimization is compared with the use of an exact Hessian. The force field Hessian in general requires more geometry steps to converge, but the additional computational cost is offset by the savings from not calculating the exact Hessian at the initial geometry.
Heteronuclear coherence transfer in solid-state nuclear magnetic resonance using a γ-encoded transferred echo experiment
Authors: Bjerring Morten , Rasmussen Jimmy Tønners , Schultz Krogshave Robert , Nielsen Niels Chr.
Published: October 2003

A novel type of solid-state nuclear magnetic resonance experiment for efficient transfer of coherence between different nuclear spin I=1/2 species under magic-angle spinning conditions is introduced. The method combines the attractive features of γ-encoded dipolar recoupling [Nielsen et al., J. Chem. Phys. 101, 1805 (1995)] with coherence transfer mediated by a longitudinal spin-order operator in a transferred echo experiment. Using two-channel rotary resonance recoupling with different phase and amplitude modulation schemes, the transferred echo sequence can be tuned to achieve dipolar recoupling and coherence transfer over a well-defined range of chemical shifts while keeping the ratio between the rf field strength and the sample spinning frequency relatively low. The method, referred to as gamma-encoded transfer echo, is described analytically, by numerical simulations for various different spin systems, and experimentally by N15 to C13 coherence transfers in a powder sample of C13, N15-labeled glycine.
Ortho-para conversion in the solid hydrogens at high pressures
Authors: Strzhemechny M. A. , Hemley R. J.
Published: October 2003

At low pressures the ortho-para conversion in H2 and D2 is a slow process governed by the magnetic dipole interaction of the nuclear magnetic moments, phonons being the main energy sink. As the pressure is raised to a few GPa and the Debye temperature increases substantially, the conversion energy finds itself in an area where phonon states are depleted and conversion slows down. The recent Raman and NMR experiments showed that the conversion rate in H2, after an initial slowdown predicted by theory, increases immensely. As to solid D2, the conversion rates have apparently not yet been directly measured under pressure. In order to explain the anomaly observed in H2, we have suggested a new conversion mechanism, in which the basic conversion-producing interaction only initiates conversion, whereas the energy is removed by rotational excitations via the stronger electric quadrupole–quadrupole interaction. Estimated conversion rates are in good qualitative agreement with available experimental observations. Here we extend the theory to solid D2, taking into account the differences between H2 and D2 in the molecular and solid-state parameters. The new libron-mediated channel is predicted to result in conversion rates for D2 under pressure that are an order of magnitude larger than at P=0.
Helium adsorbed on carbon nanotube bundles: one-dimensional and/or two-dimensional solids?
Authors: Wilson T. , Vilches O. E.
Published: October 2003

Heat capacity measurements of He4 adsorbed on closed-end single-wall carbon nanotube bundles in the temperature range 1.5 K<T<6 K are reported. Heats of adsorption Qst calculated from isotherms measured on the same calorimeter cell are included. We correlate Qst features with features of the helium heat capacity. We discuss possible interpretations of the current data.
Orientational ordering in monolayers of ortho–para hydrogen
Authors: Kokshenev V. B. , Sullivan N. S.
Published: October 2003

We discuss orientational ordering in monolayers of solid hydrogen in view of recent experimental findings in NMR studies of (ortho)c–(para)1−c-hydrogen mixtures on a boron nitride substrate. Analysis of the temperature–concentration behavior for the observed NMR frequency splitting is given on the basis of a two-dimensional (J=1)c–(J=0)1−c-rotor model with the quadrupolar coupling constant Γ0=(0.50±0.03) K and the crystalline field amplitude V0=(0.70±0.10) K derived from experiment. The two distinct pararotational short-range ordered structures are described in terms of the local alignment and orientation of the polar principal axis and are shown to be due to the interplay between the positive and negative crystalline fields. It is shown that the local structures observed below the 2D site-percolation threshold cp=0.72 are rather different from the ferromagnetic-type para–rotational ordering suggested earlier by Harris and Berlinsky.
Excess thermal resistivity in N2–CO solid solution at low carbon monoxide concentration
Authors: Stachowiak P. , Sumarokov V. V. , Mucha J. , Jeżowski A.
Published: October 2003

The results of measurements of the thermal conductivity of pure and carbon-monoxide-doped nitrogen crystals in the temperature range 1.2–26 K are presented for samples containing up to 0.7% CO molecules. It follows from a preliminary analysis that the interaction of phonons with an admixture molecule having the same mass as the host molecule is relatively weak and depends weakly on the admixture concentration within the investigated range of carbon monoxide concentrations in the nitrogen crystal.
Quantum effects in the thermal conductivity of solid krypton–methane solutions
Authors: Krivchikov A. I. , Gorodilov B. Ya. , Manzhelii V. G. , Dudkin V. V.
Published: October 2003

The dynamic interaction of a quantum rotor with its crystalline environment has been studied by measurement of the thermal conductivity of the Kr1−c(CH4)c solid solutions at c=0.05–0.75 in the temperature region 2–40 K. The thermal resistance of the solutions was mainly determined by the resonance scattering of phonons on CH4 molecules with the nuclear spin I=1 (the nuclear spin of the T species). The influence of the nuclear spin conversion on the temperature dependence of the thermal conductivity κ(T) leads to a well-defined minimum on κ(T). The temperature of the minimum depends on the CH4 concentration. It was shown that the nonmonotonic increase of the anisotropic molecular field with the CH4 concentration is caused by a compensation effect due to corrections in the mutual orientations of the neighboring rotors at c κ>0.5. The temperature dependence or Kr1−c(CH4)c is described within the Debye model of thermal conductivity taking into account the lower limit of the phonon mean free path. It is shown that phonon–rotation coupling is responsible for the anomalous temperature dependence of the thermal resistance at varying temperature. It increases strongly when the quantum character of the CH4 rotation at low temperatures changes to a classical one at high temperatures. A thermal conductivity jump (a sharp increase in κ(T) within a narrow temperature range) was also observed. The temperature position of the jump varies from 9.7 to 8.4 K when the CH4 concentration changes from 0.25 to 0.45.
Observation of growth and structure of Kr films physisorbed on Ag(111) and Ag(100)
Authors: Tosaka A. , Mitake T. , Miura T. , Arakawa I.
Published: October 2003

The structure and growth of two-dimensional crystals of Kr on Ag(111) and Ag(100) have been investigated by means of ellipsometry and eXtremely-low-current Low Energy Electron Diffraction (XLEED) under the quasi-equilibrium condition. The layered growth of a Kr film was observed up to the third layer by ellipsometry and the crystal geometry by XLEED. The Kr overlayer on Ag(100) has two types of alignment. In the predominant alignment, one of the unit vectors aligns with the 〈001〉 direction of the Ag substrate, while in the other it aligns with 〈011〉. The Kr–Kr spacing in a monolayer on Ag is 10% larger than that of the bulk.
Aggregation of protein-coated colloidal particles: Interaction energy, cluster morphology, and aggregation kinetics
Authors: Tirado-Miranda Marı́a , Schmitt Artur , Callejas-Fernández José , Fernández-Barbero Antonio
Published: October 2003

The salt-induced aggregation of polystyrene particles, partially coated with monomeric bovine serum albumin molecules, has been studied. For this purpose, the cluster fractal dimension df and the van Dongen–Ernst homogeneity parameter λ have been measured by means of static and dynamic light scattering techniques. The theoretical analysis indicates that aggregation takes places at an interaction energy minimum predicted by a modified Derjaguin–Landau–Verwey–Overbeeck (DLVO) theory when additional osmotic and elastic terms are considered. It could be shown that the depth of the energy minimum is directly related to df and λ. Moreover, the particle–particle distance within the cluster could also be assessed and compared with the interparticle distance at which the DLVO-predicted minimum appears.
Investigation of conformational changes of organic molecules sorbed in zeolites by proton magnetic resonance spectroscopy
Authors: Michel Dieter , Pampel André , Roland Jörg
Published: October 2003

An appreciable increase in spectral resolution in the H1 nuclear magnetic resonance (NMR) spectra of small organic molecules adsorbed in well-crystallized zeolites is obtained by the application of the magic angle spinning (MAS) technique, which allows to observe slight changes in the proton chemical shifts and to measure well-resolved two-dimensional (2D) NMR spectra. The behavior of 1-butene adsorbed in NaX zeolite is studied by analyzing proton chemical shifts at various temperatures and measuring intramolecular proton–proton distances by means of H1 NOESY NMR spectroscopy. Drastic changes in the NMR line shape of the protons belonging to the terminal group =CH2 are found at varying temperatures (230–340 K) and pore filling factors (between ∼0.05 and 4 molecules per large cavity). There is clear evidence that 1-butene molecules interacting with the exchangeable Na+ cations in NaX zeolites reveal a change in the conformation in comparison to those in the bulk phase.
Ion-acoustic shock waves undergoing Landau damping
Authors: Saitou Yoshifumi , Nakamura Yoshiharu
Published: October 2003

The Korteweg–de Vries equation with an additional term of Landau damping is numerically and analytically investigated. It is shown that the equation has a shock-like solution for an initial ramp signal. The temporal evolution of waveforms with various magnitudes of the Landau damping is studied for several values of the initial amplitude. Dependences of widths and velocities of the leading part on initial conditions are shown. It is found that a steepening is suppressed due to the Landau damping even when its coefficient is two orders less than those of nonlinear and dispersive terms. There is a critical relation for such a steepening to take place for a fixed height of the initial ramp. An analytical estimate of the magnitude of temporal Landau damping is given for a linear sinusoidal wave.
Thermodynamics of ammonia activation by iron cluster cations: Guided ion beam studies of the reactions of Fen+ (n=2–10,14) with ND3
Authors: Liyanage Rohana , Griffin James B. , Armentrout P. B.
Published: October 2003

The kinetic energy dependences of the reactions of Fen+ (n=2–10,14) with ND3 are studied in a guided ion beam tandem mass spectrometer over the energy range of 0–10 eV. Dehydrogenation of ammonia to form FenND+ is found to be efficient and exothermic for n=4 in agreement with previous FT-ICR studies. In contrast to the ICR studies, we also observe exothermic dehydrogenation for n=3 and 5, although these processes are much less efficient than for n=4. Other clusters also undergo this process but exhibit an energy threshold. A multitude of other primary products are observed including Fen−1ND3+ (n=2–4,9,10), FenND2+ (n=1,4–8), and Fen−1ND2+ (n=2–5), which all have reaction efficiencies that depend on cluster size. At high energies, FenN+ and FenD+ are observed along with products corresponding to Fe atom loss from the primary products. Thresholds for the various primary and secondary reactions are analyzed and bond energies for iron cluster cations bound to N, ND, ND2, and ND3 are determined. Comparisons of this thermochemistry to that for isoelectronic CD, CD2, and CD3 show that the binding of ND and ND2 is enhanced by dative interactions of the lone pair of electrons with the cluster. In contrast, the N atom is found to have a weaker bond than CD for most cluster sizes. On the basis of this thermochemistry, we find that there are barriers to the dehydrogenation reactions of about 1 eV for all the clusters, except n=3–5 exhibit an additional low energy pathway. Bond energies for larger clusters are used to estimate the bond energies of the ND and ND2 molecular fragments to iron surfaces.
Effect of heterogeneity on the elastic properties of auxetic materials
Authors: Gaspar N. , Smith C. W. , Evans K. E.
Published: October 2003

Auxetic materials are gaining practical interest for their unusual and sometimes extreme mechanical response. The process of modeling these materials so far has highlighted a number of microstructural properties that are key to these materials. However these models often rely on the assumption of homogeneity and order within the materials. Practically, a homogeneous auxetic material such as foam is unlikely to be manufactured. This work seeks to analyze the effect of fluctuations within the microstructure of the material. Numerical results show the effect of fluctuations in an auxetic granular substance and analytical work indicates the relation between microscale fluctuations and the elastic moduli for a general auxetic material.
Dressed-band approach and Coulomb corrections to the light-induced exciton Stark shift
Authors: Brandi H. S. , Latgé A. , Oliveira L. E.
Published: October 2003

In the present work, we perform a comparison of theoretical approaches involving Coulomb-interaction corrections within the Hartree–Fock approximation and the renormalized dressed-band scheme in the large detuning limit. We focus on the well-studied optical Stark shift of the exciton peak in bulk and GaAs–(Ga,Al)As semiconductor quantum wells. It is argued that the Hartree–Fock scheme has severe limitations concerning its application to real experimental situations, even in the simplest laser field–perturbative regime. It is also shown, through a comparison between experiments and a three-band Kane-dressed GaAs–(Ga,Al)As quantum well calculation, that a proper treatment of band structure and confinement effects due to the quantum well is of fundamental importance in a theoretical understanding of Stark shift experimental measurements, and that the renormalized dressed-band approach is a very convenient tool to treat, in the large detuning limit, processes involving the laser–semiconductor interaction in low-dimensional heterostructures.
Coupled magnetic–electric properties and critical behavior in multiferroic particulate composites
Authors: Nan C.-W. , Cai N. , Liu L. , Zhai J. , Ye Y. , Lin Y.
Published: October 2003

We report on a systematic experimental investigation of a class of multiferroic, three-phase particulate composite of Tb–Dy–Fe alloy, lead–zirconate–titanate (PZT), and polymer, in which a small volume fraction f of Tb–Dy–Fe alloy particles without and with the particle surfaces modified by an inactive surfactant are dispersed in PZT/polymer mixture. The measured electrical properties demonstrate that a percolation transition occurs in the three-phase composite as in normal two-phase metal–insulator continuum media. Our piezoelectric measurements also show a percolation transition which provides an experimental test of the critical behavior of the piezoelectric composites with conductive fillers in the percolation regime. Accordingly, the multiferroic composite exhibits increasing magnetoelectric response in the low f range, but such magnetoelectric response sharply drops when f approaches the percolation threshold above which the composite becomes a conductive, magnetostrictive composite only. The inactive interface between the alloy particles and the PZT/polymer matrix induced by coating surfactant on the alloy particles produces a negative effect on the piezo- and magnetoelectric properties of the composite.
Asymptotic analysis of the electrostatic wave equation in a toroidal plasma
Authors: Cardinali A. , Zonca F.
Published: October 2003

An analytical study is presented of the wave equation that describes the propagation of an electrostatic pulse in a cold plasma in a general magnetic equilibrium by means of a multiple spatial scale approach. This technique is strictly related with that discussed earlier by Zonca and Chen [Phys. Fluids B 5, 3668 (1993)], and, when applied to plasma instabilities, reduces to the well-known “ballooning formalism” [J. W. Connor, R. J. Hastie, and J. B. Taylor, Phys. Rev. Lett. 40, 396 (1978)]. A simplified equation for the scalar potential in the cold plasma limit will be derived and studied by applying the WKB asymptotic technique to describe the slow radial dependencies of the wave envelope, while the full-wave equation will be considered along the magnetic field lines. This ansatz can be entirely justified on the basis of spatial scale separation in the radial direction and for waves that have parallel group velocity faster than in the perpendicular direction. Thus, this approach could be viewed as a mixed WKB-full-wave technique.
Spatial recurrence for nonlinear magnetostatic wave excitations
Authors: Scott Mark M. , Kalinikos Boris A. , Patton Carl E.
Published: October 2003

Spatial recurrence for nonlinear magnetic excitations has been observed. The recurrence was produced from the induced modulational instability of two input magnetostatic backward volume waves in a thin yttrium iron garnet film. The nominal frequency, frequency separation, and wave number were 5.5 GHz, 8 MHz, and 100 rad/cm, respectively. The spatial recurrence of the temporal wave form included frequency doubling and cnoidal profiles. A superposition of modes based on the observed Fourier makeup of the signals and calculated nonlinear phase shifts gave a response which matched the data.
Formation and dynamics of a Z pinch in a high current capillary discharge in initial vacuum
Authors: Wyndham E. , Favre M. , Aliaga-Rossel R. , Chuaqui H. , Mitchell I. , Choi P.
Published: October 2003

Experimental conditions are presented for the formation of a Z pinch from ablated wall material in a high current, medium diameter capillary discharge without an initial filling gas. A hollow cathode geometry is used and electron beams, initiated by a laser spark, form a transient metallic plasma in the hollow cathode volume. The laser spark plasma initiates the preionization phase, whose conditions are essential for generating a stable Z pinch during the main conduction phase. During the preionizing phase wall plasma is ablated. The main discharge is derived from a small pulsed power generator, whose rate of rise of current may be varied, at current of 120 kA for 120 ns. The capillary has an internal diameter of 5 mm and length of 6 cm. From time, spatial and energy resolution of the axial soft x-ray emission, the optimum conditions of plasma formation are found to depend on the preionizing electron beams, current and the rate of rise of main discharge current applied. The temperature is obtained from soft x-ray spectra, and attains a maximum value of 80 eV. The relevance of these results in soft x-ray lasing capillary discharges is discussed.
Hyperpolarization transfer from parahydrogen to deuterium via carbon-13
Authors: Aime Silvio , Gobetto Roberto , Reineri Francesca , Canet Daniel
Published: October 2003

Hyperpolarization arising from para-hydrogen (p-H2) can be transferred via carbon-13 to deuterium after hydrogenation of a perdeuterated substrate. The model compound is acetylene-d2, hydrogenated to yield ethylene-d2. Transfer to deuterium occurs in ALTADENA experiments (the hydrogenation reaction being performed outside the magnet of the NMR spectrometer prior to the insertion of the sample tube into the NMR probe). The proposed theory, limited to the case where the two p-H2 protons remain isochronous (same chemical shift), is based on the concept of a steady-state density operator which prevails subsequently to the hydrogenation reaction. The outcome quantity is the carbon–deuterium longitudinal spin order, denoted as IzCIzD. Calculations simply involve commutators of all relevant spin quantities with the J-coupling Hamiltonian (denoted as HJ). In particular, it is shown that the necessary condition for polarization transfer toward deuterium via carbon-13 is that IzCIzD does not commute with HJ. The structure of HJ is thus of prime importance and it appears that transfer to carbon-13 occurs for both types of experiments, ALTADENA and PASADENA (hydrogenation reaction in the presence of the NMR spectrometer magnetic field). Conversely, transfer toward deuterium via carbon-13 is possible only with ALTADENA experiments.
Spatially resolved interferometric measurement of a discharge capillary plasma channel
Authors: Jones T. G. , Ting A. , Kaganovich D. , Moore C. I. , Sprangle P.
Published: October 2003

The plasma density distribution within a capillary discharge determines its performance as a waveguide for high intensity laser pulses. This paper describes direct, spatially resolved density measurements of a discharge capillary plasma channel, obtained using transverse interferometry. A transparent glass discharge capillary with square cross section was designed and constructed to provide a clear side view for interferometric imaging. Localized density profiles were reconstructed both inside and outside the capillary. Density channels suitable for high-intensity laser guiding were directly measured, revealing significant axial density gradients inside the capillary near the ends, as well as possible curvature of the channel.
Effects of substrate temperature and near-substrate plasma density on the properties of dc magnetron sputtered aluminum doped zinc oxide
Authors: Schmidt Nathan W. , Totushek Thomas S. , Kimes William A. , Callender David R. , Doyle James R.
Published: October 2003

The effects of substrate temperature and near-substrate plasma density are studied for reactively sputtered dc magnetron aluminum doped zinc oxide (ZnO:Al). Plasma density is varied using an unbalanced magnetron along with external Helmholtz coils, and is characterized using flat and cylindrical Langmuir probes. The substrate ion-to-neutral flux ratio was varied from 0.2 to about 3.5 using this technique. The ZnO:Al films were characterized by resistivity, transmission, Hall effect, and theta-two theta x-ray diffraction. Under conditions of low plasma density, for substrate temperatures below 65 °C the substrate temperature does not have a significant influence on film quality, and the film quality is relatively poor. By 88 °C the film quality is rapidly improving with temperature, and at 135 °C high quality films are produced. For substrate temperatures below 65 °C, increased plasma density at the substrate has a significant beneficial effect on the optoelectronic quality of the films. At 105 °C this effect is diminished, and by 135 °C there appears to be no improvement in film quality with increased plasma density. It is shown that the improvement of film quality at low substrate temperatures with increased plasma density is not due to substrate heating by the plasma. Possible reasons for this improvement are suggested, including plasma activation of oxygen, and the implications for low temperature growth of ZnO:Al are discussed.
Radon–Nikodym derivatives of quantum operations
Authors: Raginsky Maxim
Published: October 2003

Given a completely positive (CP) map T, there is a theorem of the Radon–Nikodym type [W. B. Arveson, Acta Math. 123, 141 (1969); V. P. Belavkin and P. Staszewski, Rep. Math. Phys. 24, 49 (1986)] that completely characterizes all CP maps S such that T−S is also a CP map. This theorem is reviewed, and several alternative formulations are given along the way. We then use the Radon–Nikodym formalism to study the structure of order intervals of quantum operations, as well as a certain one-to-one correspondence between CP maps and positive operators, already fruitfully exploited in many quantum information-theoretic treatments. We also comment on how the Radon–Nikodym theorem can be used to derive norm estimates for differences of CP maps in general, and of quantum operations in particular.
Effect of interface intermixing on giant magnetoresistance in NiFe/Cu and Co/NiFe/Co/Cu multilayers
Authors: Nagamine L. C. C. M. , Biondo A. , Pereira L. G. , Mello A. , Schmidt J. E. , Chimendes T. W. , Cunha J. B. M. , Saitovitch E. B.
Published: October 2003

This article reports on the important influence of the spontaneously built-in paramagnetic interfacial layers on the magnetic and magnetoresistive properties of NiFe/Cu and Co/NiFe/Co/Cu multilayers grown by magnetron sputtering. A computational simulation, based on a semiclassical model, has been used to reproduce the variations of the resistivity and of the magnetoresistance (MR) amplitude with the thickness of the NiFe, Cu, and Co layers. We showed that the compositionally intermixed layers at NiFe/Cu interfaces, which are paramagnetic, reduce the flow of polarized electrons and produce a masking on the estimated mean-free path of both types of electrons due to the reduction of their effective values, mainly for small NiFe thickness. Moreover, the transmission coefficients for the electrons decrease when Fe buffer layers are replaced by NiFe ones. This result is interpreted in terms of the variations of the interfacial intermixing and roughness at the interfaces, leading to an increase of the paramagnetic interfacial layer thickness. The effect provoked by Co deposition at the NiFe 16 Å/Cu interfaces has also been investigated. The maximum of the MR amplitudes was found at 5 Å of Co, resulting in the quadruplication of the MR amplitude. This result is partially attributed to the interfacial spin-dependent scattering due to the increase of the magnetic order at interfaces. Another effect observed here was the increase of the spin-dependent scattering events in the bulk NiFe due to a larger effective NiFe thickness, since the paramagnetic interfacial layer thickness is decreased.
Effects of trapped electron temperature, dust charge variations, and grain radius on the existence of the dust-ion-acoustic waves
Authors: El-Labany S. K. , Moslem Waleed M. , Mowafy A. E.
Published: October 2003

The ionization source model is considered to study the effects of trapped electron temperature, dust charge variations, and grain radius on the nonlinear dust ion acoustic waves (DIAWs) in dusty plasmas having trapped electrons. It has been shown that the nonlinear DIAWs damp waves and these waves are governed by a damped modified Korteweg–de Vries equation. It is found that only compressive dust ion acoustic solitons can propagate in dusty plasmas with trapped electrons. The amplitude and the width of the solitons depend mainly on the trapped electron temperature, dust charge variations and grain radius. The existence of the solitons is independent of the trapped electron temperature. The findings of this investigation may be useful in understanding laboratory plasma phenomena and astrophysical situations.
On decoherence
Authors: Dell’Antonio Gianfausto
Published: October 2003

Using a quantum particle in R3 as a toy model, and following the rules of Schrödinger’s quantum mechanics, we discuss to which extent one may be able to use “decoherence” to view the quantum particle as a “classical” measuring apparatus to measure position. We discuss also very briefly the measurement of momentum and the case of quantum optics.
Alternative electrostatic Green’s function for a long tube
Authors: Barlow S. E.
Published: October 2003

This note describes an expression for the electrostatic Green’s function in a long conducting tube. The expression allows one to readily compute the potentials and fields at and in the vicinity of the singularity where other methods have difficulty.
Charge-based deep level transient spectroscopy of phosphorous-doped homoepitaxial diamond
Authors: Gaudin Olivier , Troupis Damianos K. , Jackman Richard B. , Nebel Christoph E. , Koizumi Satoshi , Gheeraert Etienne
Published: October 2003

A form of charge-based deep level transient spectroscopy (Q-DLTS) has been used to investigate electrically active defects within three phosphorus (P)-doped, n-type, homoepitaxial diamond films, grown by the chemical vapor deposition technique, in an attempt to obtain a Q-DLTS signal related to the P-donor level itself. Four distinct peaks were observed in the Q-DLTS spectra, two of which could be fully analyzed. One of the other two peaks overlapped other structures in the measured spectra and so could not be fully characterized, while the fourth emerged at temperatures corresponding to the limit of the experimental system used. The two fully characterized peaks arose through the presence of levels with activation energies within the range 0.42–0.6 eV depending on the sample, contact scheme, and charging time used. One of these two peaks was only observed within two of the three samples. It occurred as a shoulder on the left-hand side of a more prominent and sharp Q-DLTS feature. Both of these Q-DLTS peaks are thought to originate from the P-related donor level in diamond, although their Q-DLTS activation energy values appeared to be scattered and most of the time significantly shallower than the value of 0.6 eV corresponding to the ground level of the P-related donor level. Such discrepancies are thought to arise essentially from retrapping effects, likely due to strong leakage currents at the metal/diamond interface. Improvements to the accuracy of the measurements made here is therefore expected if reliable, good quality, Schottky contacts to n-type diamond become obtainable.
Materials science and integration bases for fabrication of (BaxSr1−x)TiO3 thin film capacitors with layered Cu-based electrodes
Authors: Fan W. , Kabius B. , Hiller J. M. , Saha S. , Carlisle J. A. , Auciello O. , Chang R. P. H. , Ramesh R.
Published: October 2003

The synthesis and fundamental material properties of layered TiAl/Cu/Ta electrodes were investigated to achieve the integration of Cu electrodes with high-dielectric constant (κ) oxide thin films for application to the fabrication of high-frequency devices. The Ta layer is an excellent diffusion barrier to inhibit deleterious Cu diffusion into the Si substrate, while the TiAl layer provides an excellent barrier against oxygen diffusion into the Cu layer to inhibit Cu oxidation during the growth of the high-κ layer in an oxygen atmosphere. Polycrystalline (BaxSr1−x)TiO3 (BST) thin films were grown on the Cu-based bottom electrode by rf magnetron sputtering at temperatures in the range 400–600 °C in oxygen, to investigate the performance of BST/Cu-based capacitors. Characterization of the Cu-based layered structure using surface analytical methods showed that two amorphous oxide layers were formed on both sides of the TiAl barrier, such that the oxide layer on the free surface of the TiAl layer correlates with TiAlOx, while the oxide layer at the TiAl/Cu interface is an Al2O3-rich layer. This double amorphous barrier layer structure effectively prevents oxygen penetration towards the underlying Cu and Ta layers. The TiAlOx interfacial layer, which has a relatively low dielectric constant compared with BST, reduced the total capacitance of the BST thin film capacitors. In addition, the layered electrode-oxide interface roughening observed during the growth of BST films at high temperature, due to copper grain growth, resulted in large dielectric loss on the fabricated BST capacitors. These problems were solved by growing the BST layer at 450 °C followed by a rapid thermal annealing at 700 °C. This process significantly reduced the thickness of the TiAlOx layer and interface roughness resulting in BST capacitors exhibiting properties suitable for the fabrication of high-performance high-frequency devices. In summary, relatively high dielectric constant (280), low dielectric loss (0.007), and low leakage current (<2×10−8 A/cm2 at 100 kV/cm) were achieved for BST thin film capacitors with Cu-based electrodes.
Comment on “On the consistency of the collisionless sheath model” [Phys. Plasmas 9, 4427 (2002)]
Authors: Benilov M. S.
Published: October 2003

Two points are raised concerning the recently published Letter on the collisionless space-charge sheath and the subsequent discussion: an appropriate identification of the contribution of the sheath to the total ionization rate resolves the paradox of ionization in the sheath being infinitely larger than in the adjacent plasma; the concept of a sheath of the order of Debye length with the electron density much smaller than the ion density is contradictory.
Wave driven magnetic reconnection in the Taylor problem
Authors: Fitzpatrick Richard , Bhattacharjee Amitava , Ma Zhi-Wei , Linde Timur
Published: October 2003

An improved Laplace transform theory is developed in order to investigate the initial response of a stable slab plasma equilibrium enclosed by conducting walls to a suddenly applied wall perturbation in the so-called Taylor problem. The novel feature of this theory is that it does not employ asymptotic matching. If the wall perturbation is switched on slowly compared to the Alfvén time then the plasma response eventually asymptotes to that predicted by conventional asymptotic matching theory. However, at early times there is a compressible Alfvén wave driven contribution to the magnetic reconnection rate which is not captured by asymptotic matching theory, and leads to a significant increase in the reconnection rate. If the wall perturbation is switched on rapidly compared to the Alfvén time then strongly localized compressible Alfvén wave-pulses are generated which bounce backward and forward between the walls many times. Each instance these wave-pulses cross the resonant surface they generate a transient surge in the reconnection rate. The maximum pulse driven reconnection rate can be much larger than that predicted by conventional asymptotic matching theory.
Fundamental mode 5 GHz surface-acoustic-wave filters using optical lithography
Authors: Makkonen T. , Plessky V. P. , Steichen W. , Chamaly S. , Poirel C. , Solal M. , Salomaa M. M.
Published: October 2003

Resonators and bandpass filters have been implemented in the 5 GHz frequency range, based on “longitudinal leaky” surface-acoustic waves on standard YZ-cut lithium niobate substrate. The synchronous one-port resonators constituting a ladder filter operate in the fundamental mode. The electrode width in the resonators is above 0.25 μm, thus making them readily accessible for fabrication with optical lithography. Test resonators are fabricated to study the effects of the metallization ratio and aperture on the resonator behavior. For the prototype filter, a center frequency of 5.20 GHz, a wide fractional 3 dB bandwidth of 6.3%, a minimum insertion loss of 3.3 dB and a high stopband suppression of 25 dB have been achieved.