Pairwise thermal entanglement in the n-qubit (n5) Heisenberg XX chain

In this Letter, we have calculated the concurrence of the pairwise thermal entanglement for the four-qubit and five-qubit Heisenberg XX chain. It is found that there is a great difference between the even-qubit and the odd-qubit chain in the aspect of the critical temperature and of the existence of the entanglement for the case of the qubit number n no more than 5.     

0-extended supergravity and Chern-Simons theories

We give generalizations of extended Poincaré supergravity with arbitrarily many supersymmetries in the absence of central charges in three dimensions by gauging its intrinsic global SO(N) symmetry. We call these ₀ (Aleph-null) supergravity theories. We further couple a non-Abelian supersymmetric Chern-Simons theory and an Abelian topological BF theory to ₀ supergravity. Our result overcomes the previous difficulty for supersymmetrization of Chern-Simons theories beyond N = 4. This feature is peculiar to the Chern-Simons and BF theories including supergravity in three dimensions. We also show that dimensional reduction schemes for four-dimensional theories such as N = 1 self-dual supersymmetric Yang-Mills theory or N = 1 supergravity theory that can generate ₀ globally and locally supersymmetric theories in three dimensions. As an interesting application, we present ₀ supergravity Liouville theory in two dimensions after appropriate dimensional reduction from three dimensions.     

Size-dependent oxidation of Pdn (n ? 13) on alumina/NiAl(110): Correlation with Pd core level binding energies

Small Pd clusters Pd_n (n = 1, 4, 7, 10, 13) deposited on alumina/NiAl(110) at room temperature were examined by X-ray photoelectron spectroscopy (XPS), as-deposited and after exposure to O₂ at temperatures ranging from 100 to 500 K. After O₂ exposure at 100 K, the Pd clusters showed XPS shifts indicative of oxidation. The exception was Pd₄, which did not oxidize under any conditions. The inertness of Pd₄/alumina/NiAl(110) appears to be correlated with a significantly higher-than-expected Pd 3d binding energy, which we attribute to a particularly stable valence shell. None of the clusters examined oxidized during O₂ exposures at 300 K or above, but He⁺ scattering showed that oxygen was bound on the cluster surfaces. Upon heating, all the oxygen associated with these small clusters appeared to spill over and react with the alumina/NiAl(110) support.     

Exclusive photoproduction of mesons at HERA

The exclusive photoproduction reaction γp→p has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb⁻¹. The measurement covers the kinematic range 60<W<220 GeV and Q²<1 GeV², where W is the photon–proton centre-of-mass energy and Q² is the photon virtuality. These results, which represent the analysis of the full ZEUS data sample for this channel, are compared to predictions based on perturbative QCD.     

-Particle radioactivity from LR 115 by two methods of analysis

LR115 track detectors were exposed to samples of Moroccan phosphate and phosphogypsum to measure their -particle radioactivity. Then two formalisms were used for the dosimetry: simulation by a Monte Carlo method and determination of concentrations from a numerically integrated track registration equation. The results were compared with those deduced γ-ray spectrometry.     

Off-shell Bethe ansatz equation for osp(21) Gaudin magnets

The semi-classical limit of the algebraic Bethe ansatz method is used to solve the theory of Gaudin models. Via off-shell Bethe ansatz method we find the spectra and eigenvectors of the N−1 independents Gaudin Hamiltonians with symmetry osp(21). We also show how the off-shell Gaudin equation solves the trigonometric Knizhnik–Zamolodchikov equation.     

Contours of constant Δ and Ψ in the 2–4 plane for the ellipsometric functions

Contour graphs of ₂ vs ₄ for different film thicknesses and a range of angles of incidence have been plotted for the ellipsometric functions Δ and Ψ in both the reflection and transmission modes. In the case of reflection ellipsometry, when the plots for Δ_R and Ψ_R are superimposed, the two sets of contours cross nearly at right angles over a large part of the field, this being indicative of the high accuracy obtainable in using this technique to determine ₄ and ₂ and hence the optical constants, n and k, for the film material. The reflection ellipsometric technique is accurate over angles of incidence between 30° and 75° and for a range of film thicknesses between λ/30 and 5λ. Transmission ellipsometry is less useful, due to anomalies in both X_s and X_p where sudden phase changes of ±π occur in regions of interest. There is also the possibility of multiple solutions, although the use of a multiangle technique would enable the “correct” values to be more easily determined.     

Real next-to-next-to-leading-order QCD corrections to and hadroproduction in association with a photon

We update the study of the QCD corrections to direct J/ψ and hadroproduction in association with a photon in the QCD-based approach of the Colour-Singlet (CS) Model. After comparison with the recent full next-to-leading-order (NLO) computation for this process, we provide an independent confirmation to the inclusive case that NLO QCD corrections to quarkonium-production processes whose LO exhibits a non-leading P_T behaviour can be reliably computed at mid and large P_T by considering only the real emission contributions accompanied with a kinematical cut. In turn, we evaluate the leading part of the contributions, namely those coming from (J/ψ,)+γ associated with two light partons. We find that they are dominant at mid and large P_T. This confirms our expectations from the leading P_T scaling of the new topologies appearing at NNLO. We obtain that the yield from the CS becomes one order of magnitude larger than the upper value of the potential colour-octet yield. The polarisation of the quarkonia produced in association with a photon is confirmed to be longitudinal at mid and large P_T.     

(Q) corrections to particle multiplicity ratios in gluon and quark jets

The order (Q²) correction to the particle multiplicity ratio in gluon and quark jets is calculated in QCD. Through (Q²) we find

, with r = <n>_{gluon jet}/<n>_{quark jet}. This ratio is independent of the opening angle chosen to define the jets.     

Functionalization of multiwalled carbon nanotubes for reinforcing of poly(l-lactide-co--caprolactone) biodegradable copolymers

Up to now, synthetic polymers and biomacromolecules have been grafted or assembled onto the convex surface of carbon nanotubes (CNTs) via covalent bonds or chemisorptions. In this research, poly(l-lactide-co--caprolactone)-functionalized multiwalled carbon nanotubes (MWCNT-OH-g-PCLA)s are synthesized by in situ ring-opening copolymerization of l-lactide (LA) and -caprolactone (CL) using stannous octanoate and hydroxylated MWCNTs (MWCNT-OHs) as the initiating system. The pristine MWCNTs are modified to possess carboxyl groups and then hydroxyl groups. MWCNT-OHs are used as coinitiators to polymerize LA and CL by the surface-initiated ring-opening polymerization. The FT-IR spectra, SEM and TEM micrographs revealed that the PCLA grafted form the sidewall of MWCNTs strongly. The TGA analysis indicates that about 75 wt% of functionalized MWCNTs with PCLA belongs to grafted PCLA and the remaining 25 wt% to the initial MWCNT-OH.     

Diffusive EPR line width behaviour in two-dimensional Cu(Hippurate)2 4H2O single crystal

X-band EPR measurements were performed at room temperature on layered Cu(Hippurate)₂4H₂O single crystals. Despite the dimeric molecular structure the EPR spectra are characteristic for individual Cu-complexes with square-pyramidal structure and g-factors: g_x=2.045, g_y=2.085 and g_z=2.346. The anticipated zero-field splitting from dimers with S=1 is averaged out by interdimer exchange coupling within the layers. The dimers in adjacent layers are not exchange coupled as we determined from the two-component EPR spectra. Thus, the crystal is an ideal 2D magnetic system and shows a strong spin diffusion effect in the EPR line width. The spin diffusion contribution to the line width is described as P(3cos²Θ−1)² with which is much higher compared to other 2D copper(II) crystals. The background line width is due to dipolar coupling and non-resolved hyperfine structure. Exchange coupling was determined from the exchange narrowing effect as of about 0.1 cm⁻¹.     

Hybrid artificial neural network segmentation of precise and accurate inversion recovery (PAIR) images from normal human brain

This paper presents a novel semi-automated segmentation and classification method based on raw signal intensities from a quantitative T1 relaxation technique with two novel approaches for the removal of partial volume effects. The segmentation used a Kohonen Self Organizing Map that eliminated inter- and intra-operator variability. A Multi-layered Backpropagation Neural Network was able to classify the test data with a predicted accuracy of 87.2% when compared to manual classification. A linear interpolation of the quantitative T1 information by region and on a pixel-by-pixel basis was used to redistribute voxels containing a partial volume of gray matter (GM) and white matter (WM) or a partial volume of GM and cerebrospinal fluid (CSF) into the principal components of GM, WM, and CSF. The method presented was validated against manual segmentation of the base images by three experienced observers. Comparing segmented outputs directly to the manual segmentation revealed a difference of less than 2% in GM and less than 6% in WM for pure tissue estimations for both the regional and pixel-by-pixel redistribution techniques. This technique produced accurate estimates of the amounts of GM and WM while providing a reliable means of redistributing partial volume effects.     

Oxygen induced segregation of aluminum to α-Cu-Al(1 0 0) alloy surfaces studied by low energy ion scattering and X-ray photoelectron spectroscopy

The effect of annealing temperature on the surface composition of α-Cu-Al(1 0 0) alloys for aluminum concentrations of 5, 12 and 17 at% was investigated using X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Two initial states of the sample surfaces were examined: sputter-cleaned and oxidized. The effect of annealing temperature on segregation is different for sputter-cleaned and oxidized samples. Aluminum preferential sputtering and strong oxygen induced aluminum segregation were detected on all examined samples. Whilst for the sputter-cleaned surfaces a small thermal induced segregation was observed, the combination of annealing and oxygen exposure resulted in aluminum enrichment in the 100-300% range relative to the bulk concentration. The segregation rate is proportional to the aluminum concentration for sputter-cleaned surfaces and displays a maximum for the oxidized α-Cu-Al(12 at.%)(1 0 0) surface.     

Initial growth of platinum on oxygen-covered Ni(1 1 0) surfaces

The initial growth of Pt on the Ni(1 1 0)-(3 × 1)-O and NiO(1 1 0) surfaces has been studied by coaxial impact collision ion scattering spectroscopy (CAICISS), low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). Prior to Pt deposition, the atomic structure of the near-surface regions of the Ni(1 1 0)-(3 × 1)-O and NiO(1 1 0) structures were studied using CAICISS, finding changes to the interlayer spacings due to the adsorption of oxygen. Deposition of Pt on the Ni(1 1 0)-(3 × 1)-O surface led to a random substitutional alloy in the near-surface region at Pt coverages both below and in excess of 1 ML. In contrast, when the surface was treated with 1800 L of atomic oxygen in order to form a NiO(1 1 0) surface, a thin Pt layer was formed upon room temperature Pt deposition. XPS and LEED data are presented throughout to support the CAICISS observations.     

A quantum-chemical study of LiC=O interactions in polyester-based polymer electrolytes

Quantum-chemical calculations on model ester molecules have been performed to study the interactions of carbonyl groups with lithium cation. The preferred conformations of the complexes and their stabilization energies have been determined. The largest complexation energy has been obtained for Li⁺ binding to four carbonyl groups. The vibrational frequency calculations have been used to predict the changes in the IR spectrum of polyester upon Li⁺ complexation. For the most stable complex the red-shift of about − 29 to − 24 cm^− 1 in the frequency of the C=O stretching mode has been calculated in a good agreement with the experimental value [I.D. Wu, F. C. Chang, Polymer 48 (2007) 989].     

Comparison of the interaction of Pd with positively and negatively poled LiNbO3(0 0 0 1)

To investigate the possibility of manipulating the surface chemical properties of finely dispersed metal films through ferroelectric polarization, the interaction of palladium with oppositely poled LiNbO₃(0 0 0 1) substrates was characterized. Low energy ion scattering indicated that the Pd tended to form three-dimensional clusters on both positively and negatively poled substrates even at the lowest coverages. X-ray photoelectron spectroscopy (XPS) showed an upward shift in the binding energy of the Pd 3d core levels of 0.9 eV at the lowest Pd coverages, which slowly decayed toward the bulk value with increasing Pd coverage. These shifts were independent of the poling direction of the substrate and similar to those attributed to cluster size effects on inert supports. Thus, the spectroscopic data suggested that Pd does not interact strongly with LiNbO₃ surfaces. The surface chemical properties of the Pd clusters were investigated using CO temperature programmed desorption. On both positively and negatively poled substrates, CO desorption from freshly deposited Pd showed a splitting of the broad 460 K desorption peak characteristic of bulk Pd into distinct peaks at 270 and 490 K as the Pd coverage was decreased below 1.0 ML; behavior that also resembles that seen on inert supports. It was found that a small fraction of the adsorbed CO may dissociate (<2%) for Pd on both positively and negatively poled substrates. The thermal response of the smaller Pd clusters on the LiNbO₃ surfaces, however, was different from that of inert substrates. In a manner similar to Nb₂O₅, when CO desorption experiments were carried out a second time, the adsorption capacity decreased and the higher temperature desorption peak shifted from 490 K to below 450 K. This behavior was independent of the substrate poling direction. Thus, while there was evidence that LiNbO₃ does not behave as a completely inert support, no significant differences between positively and negatively poled surfaces were observed. This lack of sensitivity of the surface properties of the Pd to the poling direction of the substrate is attributed to the three-dimensional Pd clusters being too thick for their surfaces to be influenced by the polarization of the underlying substrate.     

Ion dependence of magnetic anisotropy in MFe2O4 (MFe, Co, Mn) nanoparticles synthesized by high-temperature reaction

The influence of different M²⁺ cations on the effective magnetic anisotropy of systems composed of MFe₂O₄ (M=Fe, Co and Mn) nanoparticles was investigated. Samples were prepared by the high-temperature (538 K) solution phase reaction of Fe (acac)₃, Co (acac)₂ and Mn (acac)₂ with 1,2 octanodiol in the presence of oleic acid and oleylamine. The final particles are coated by an organic layer of oleic acid that prevents agglomeration. Transmission electron microscopy (TEM) images show that particles present near spherical form and a narrow grain size distribution, with mean diameters in the range of 4.5–7.6 nm. Powder samples were analyzed by ac susceptibility and Mössbauer measurements, and K_eff for all samples was evaluated using both techniques, showing a strong dependence on the nature of the divalent cation.