bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical studies of shear banding in interface shear tests using a new strain calculation method
Authors: Wang Jianfeng , Gutierrez Marte S. , Dove Joseph E. 
Published: February 2007

AbstractStrain localization is closely associated with the stress–strain behaviour of an interphase system subject to quasi‐static direct interface shear, especially after peak stress state is reached. This behaviour is important because it is closely related to deformations experienced by geotechnical composite structures. This paper presents a study using two‐dimensional discrete element method (DEM) simulations on the strain localization of an idealized interphase system composed of densely packed spherical particles in contact with rough manufactured surfaces. The manufactured surface is made up of regular or irregular triangular asperities with varying slopes. A new simple method of strain calculation is used in this study to generate strain field inside a simulated direct interface shear box. This method accounts for particle rotation and captures strain localization features at high resolution. Results show that strain localization begins with the onset of non‐linear stress–strain behaviour. A distinct but discontinuous shear band emerges above the rough surface just before the peak stress state, which becomes more expansive and coherent with post‐peak strain softening. It is found that the shear bands developed by surfaces with smaller roughness are much thinner than those developed by surfaces with greater roughness. The maximum thickness of the intense shear zone is observed to be about 8–10 median particle diameters. The shear band orientations, which are mainly dominated by the rough boundary surface, are parallel with the zero extension direction, which are horizontally oriented. Published in 2007 by John Wiley & Sons, Ltd.
Triaxial behaviour of transversely isotropic materials: application to sedimentary rocks
Authors: Rouabhi A. , Tijani M. , Rejeb A. 
Published: February 2007

AbstractFailure and long‐term behaviour of oriented solids are studied. Transversely isotropic materials are considered and a mathematical formulation that respect the material symmetry is developed and applied to model the triaxial behaviour of sedimentary rocks. Two failure criteria and a viscoplastic constitutive model that describe, respectively, triaxial failure and triaxial creep tests are presented and discussed. The application of the developed models to describe the mechanical behaviour of Tournemire shale shows that theoretical predictions are in good agreement with the experimental data. In the present paper, the developed approach is applied to sedimentary rock materials, nevertheless, it can be generalized to any material that exhibits transverse isotropy. Copyright © 2007 John Wiley & Sons, Ltd.
Different attitudes of Chinese patients and their families toward truth telling of different stages of cancer
Authors: Jiang Yu , Liu Chang , Li Jun‐Ying , Huang Mei‐Juan , Yao Wen‐Xiu , Zhang Ru , Yao Bing , Du Xiao‐Bo , Chen Jing , Xie Ke , Zhao Xia , Wei Yu‐Quan 
Published: February 2007

AbstractObjective: Cancer patients and their families differed in their attitude toward truth telling. The objective is to investigate different attitudes of Chinese patients or families toward whether and how to disclose diagnosis to patients with different stages of cancer and to examine the difference between the two groups.Methods: A questionnaire was delivered to 1023 participants.Results: Three hundred and eighty‐two patients and 482 families completed the questionnaire. Cancer patients were more likely than families to believe that patient should be informed of the diagnosis (early‐stage, 90.8 vs 69.9%, P<0.001; terminal stage, 60.5 vs 34.4%, P<0.001), and that doctor‐in‐charge was the appropriate person to disclose the diagnosis. Most participants thought that patient should be disclosed immediately after the diagnosis. Nearly half of participants reported that patient should be disclosed in a quiet and undisturbed room. When the hypothetic diagnosis changed from early‐stage cancer to terminal illness, the number of participants, who wanted patient to know the diagnosis, decreased significantly.Conclusion: Our findings indicated that Chinese cancer patients and their families differed in their attitude toward truth telling and the attitudes toward such a disclosure were influenced by disease stage. Physicians should realize this phenomenon and pay more attention to the skills of how to disclose the cancer diagnosis. Copyright © 2007 John Wiley & Sons, Ltd.
Analycys: A database for conservation and conformation of disulphide bonds in homologous protein domains
Authors: Thangudu Ratna R. , Sharma Priyanka , Srinivasan N. , Offmann Bernard 
Published: February 2007

AbstractDisulphide bonds in proteins are known to play diverse roles ranging from folding to structure to function. Thorough knowledge of the conservation status and structural state of the disulphide bonds will help in understanding of the differences in homologous proteins. Here we present a database for the analysis of conservation and conformation of disulphide bonds in SCOP structural families. This database has a wide range of applications including mapping of disulphide bond mutation patterns, identification of disulphide bonds important for folding and stabilization, modeling of protein tertiary structures and in protein engineering. The database can be accessed at: http://bioinformatics.univ‐reunion.fr/analycys/. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Walking through the protein sequence space: Towards new generation of the homology modeling
Authors: Frenkel Zakharia M. , Trifonov Edward N. 
Published: February 2007

AbstractA new method is proposed to reveal apparent evolutionary relationships between protein fragments with similar 3D structures by finding “intermediate” sequences in the proteomic database. Instead of looking for homologies and intermediates for a whole protein domain, we build a chain of intermediate short sequences, which allows one to link similar structural modules of proteins belonging to the same or different families. Several such chains of intermediates can be combined into an evolutionary tree of structural protein modules. All calculations were made for protein fragments of 20 aa residues. Three evolutionary trees for different module structures are described. The aim of the paper is to introduce the new method and to demonstrate its potential for protein structural predictions. The approach also opens new perspectives for protein evolution studies. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Analysis of power enhancement of terahertz waves in periodically inverted GaP pumped at 1.55 mm
Authors: Tomita I. , Suzuki H. , Rungsawang R. , Ueno Y. , Ajito K. 
Published: February 2007

AbstractWe have generated terahertz (THz) waves by difference frequency generation (DFG) with a 1.55 μm pump laser. 1.55 μm pump beams were effectively converted to 1 THz waves through a periodically χ(2)‐inverted GaP stack fabricated by direct wafer bonding. The output efficiency was an order of magnitude larger than that of typical χ(2) materials such as lithium niobate employing a similar DFG method. To investigate the increase in output power due to quasi‐phase matching including optical losses, we measured its dependence on stack length. From the measured data, we analyze the conditions for effective power enhancement and show that it takes place if the pump‐beam loss, α, is much smaller than that of the THz waves, α3 (or the pump‐beam attenuation length, 1/α, is much longer than that of the THz waves, 1/α3), which is achieved by improving the bonding quality of the stack. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of vacancies in the mobility of dislocations and grain boundaries in magnesium
Authors: Lambri O. A. , Massot M. , Riehemann W. , Lucioni E. J. , Plazaola F. , García J. A. 
Published: February 2007

AbstractVacancy flux or supersaturation enhances grain‐boundary mobility, but experimental evidence is not large and in many cases the role of vacancies is only inferred indirectly. We will show effectively in the present work the importance of the vacancy role in grain‐boundary mobility in commercial pure and high‐purity magnesium using mechanical spectroscopy, electrical resistivity and positron annihilation spectroscopy. It has been found that the mobility decrease of grain boundaries and dislocations is related to vacancy concentration reduction attained after the homogenisation treatment. Indeed, the largest vacancy concentration reduction is observed between 420 and 500 K. Unlocking grain boundaries and dislocations requires new vacancies, generated at temperatures above 500 K. In addition, a new damping peak related to vacancies was discovered at 490 K for an oscillating frequency of 1 Hz. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface melting of close‐packed Mg(0001), compared with Al(111)
Authors: Yang Jianyu , Hu Wangyu , Xiao Shifang , Yi Guojun 
Published: February 2007

AbstractUsing molecular dynamics simulations and an analytic embedded‐atom method, a comparative study of the surface anharmonicity for the close‐packed surface of Mg(0001) and Al(111) is presented in the temperature range from 0 K to their melting temperatures. The temperature dependences of the surface phonon frequencies, the mean square vibrational amplitudes of surface atoms and the layer structure factor are calculated. The calculated results are in good agreement with the available experimental data. Although with the same atomic arrangement for the top layer, Al(111) preserves its crystalline order in the temperature range considered, and Mg(0001) exhibits surface melting. The possible mechanism for the different melting behaviors of the two surfaces is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spontaneous emission enhancement in quantum cascade structures in the TeraHertz domain
Authors: Todorov Yanko , Sagnes Isabelle , Gennser Ulf , Coron Nöel , Minot Christophe , Abram Izo 
Published: February 2007

AbstractWe have fabricated and studied MOCVD grown quantum cascade devices operating in the far infrared frequency range (at about 4 THz). The devices are processed into double metal waveguides, in order to investigate the Purcell effect on the spontaneous emission rate due to the electromagnetic field confinement. Intersubband electroluminescence is outcoupled by a metallic grating, which also serves as the cavity upper mirror. The power collected per quantum cascade period increases when the device thickness is reduced, indicating a Purcell spontaneous emission enhancement factor up to about 50. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InAs/InP quantum dots (QD): from fundamental understanding to coupled QD 1.55 µm laser applications
Authors: Cornet C. , Hayne M. , Schliwa A. , Doré F. , Even J. , Bimberg D. , Moshchalkov V. V. , Loualiche S. 
Published: February 2007

AbstractWe report a brief overview of recent research developments on InAs/InP quantum dots (QDs). Eight‐band k·p calculations are performed on single InAs/InP QDs, and the impact of substrate orientation ((311)B or (100)) on electronic and optical properties is studied. The quaternary alloy InGaAsP capping is studied by magneto‐photoluminescence. It is found to induce a better electronic confinement than InP. It is then demonstrated that high QDs density can be reached on such a system, leading to lateral coupling between dots. Calculations and (magnetophoto‐) (photo‐) (electro‐) luminescence experiments are used to demonstrate that the lateral coupling leads to miniband effects, and to a better charge carrier redistribution between QDs for laser applications. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton binding energy in type II quantum dots
Authors: Gomes P. F. , Godoy M. P. F. , Veloso A. B. , Nakaema M. K. K. , Iikawa F. , Brasil M. J. S. P. , Bortoleto J. R. R. , Cotta M. A. , Madureira J. R. 
Published: February 2007

AbstractWe investigated the optical properties of self‐assembled InP/GaAs quantum dots using continuous‐wave and time‐resolved photoluminescence spectroscopy. The thermal activation energy, which is directly related to the exciton binding energy in this system, was obtained by photoluminescence measurements as a function of temperature. We obtained thermal activation energies of 6–9 meV for undoped quantum dots and 13 meV for the modulation‐doped sample. Those values are in good agreement with calculated results. The dots presented a recombination time of ∼ 0.8–1.1 ns, which is surprisingly small for a type‐II system. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dilute magnetic bulk GaN semiconductor and nanostructures
Authors: Ferguson I. T. 
Published: February 2007

AbstractGa1–xMnxN and Ga1–xFexN thin films and nanostructures were grown by metalorganic chemical vapor deposition. High resolution X‐ray diffraction studies demonstrate that the material is high quality single phase similar in quality and lattice parameter to unalloyed GaN. The as‐grown epitaxial films exhibit ferromagnetic hysteresis at room temperature as measured by SQUID magnetometry; the strength of the observed volume magnetization is almost an order stronger in similarly grown Mn‐doped samples relative to Fe‐doped samples. Raman spectroscopy revealed no significant strain introduced by the transition metal incorporation and a low free carrier concentration, and the most prominent additional mode in Mn‐doped GaN is attributed to vacancy‐related local vibrational modes of the GaN host lattice. A novel growth method has been developed to produce GaN‐based nanostructures using a two‐step process (GaN deposition followed by an activation step) at low growth temperatures (<850 °C) and V‐III ratios (<30). GaMnN nanostructures were grown by introducing Mn to GaN flows under optimal conditions for the formation of nanostructure without the need of an activation step. Manganese icorporation has the tangential benefit that Mn acts as an anti‐surfactant, and promotes the low‐temperature nucleation of these nanostructures. In addition, experiments have been conducted in which Fe was incorporated into GaN nanostructures at 800 °C, and room temperature ferromagnetic behavior of GaFeN nanostructures was observed. Atomic force microscopy measurements revealed that Fe, like Mn, affected the surface morphology of the nanostructures by reducing the nanostructure size. These nanostructures showed a systematic variation in coercive field and saturation magnetization with Fe incorporation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic electrodes in the onion state for spin injection into semiconductors
Authors: Gallo P. , Lombez L. , Bournel A. , Amand T. , Camps T. , Marie X. , Havard E. , Fontaine C. , Arnoult A. 
Published: February 2007

AbstractWe present electrodes in the onion state for spin injection into semiconductors. The electrodes are in the so called “onion state” which allows them to be self‐aligned, and not to generate any stray‐field. The application discussed here is the spin Field Effect Transistor. It is demonstrated that in order to match the in‐plane polarization of the injected carriers, one has to use a quantum wire grown on a (110) surface as a channel. The channel length for the spins to fully switch is calculated to be the order of 150 nm for a gate electric field of 150 kV/cm to 300 kV/cm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitonic polaron in InAs/GaAs self‐assembled quantum dot molecules
Authors: Adames M. , Bedoya M. , Camacho B. A. S. 
Published: February 2007

AbstractWe study the excitonic polaron formation in two InAs/GaAs coupled quantum dots. We calculate the coupling between the exciton and the LO‐phonon states by using the Fröhlich Hamiltonian, from which we determine the excitonic polaron states varying the quantum dot separation. We study the dependence on the excitonic polaron formation with the coupling between the dots. Polaron formation strongly modifies the energy spectra due to the appearance of several anticrossings in the excited states. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo calculation of electron transport properties of GaxIn1–xN
Authors: Akarsu M. , Aydoğu S. , Özbaş Ö. 
Published: February 2007

AbstractThe Monte Carlo method is used to simulate electron transport for electric field strength up to 500 kV/cm in GaxIn1–xN for composition x range from 0.0 to 1.0. Calculations of the electron steady‐state drift velocity, average energy and valley occupancy are examined at a temperature of 300 K. Scattering mechanisms considered in the simulations are ionized impurity, polar optical phonon, acoustic phonon, non‐polar optical phonon, intervalley, dislocation and alloy scatterings. Effects of the alloy scatterings on the drift velocity are examined. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of substrate temperature on some of the optical parameters of CuInS2 films
Authors: Aksay S. , Altıokka B. 
Published: February 2007

AbstractPolycrystalline CuInS2 films have been grown by spray pyrolysis method at different substrate temperatures, a simple method which can produce low cost and highly absorbing samples. Optical characteristics of the CuInS2 films have been analyzed using spectrophotometer in the wavelength range of 400–900 nm. The absorption spectra of the films showed that this compound is a direct band gap material and gap values varied between 1.51–1.80 eV, depending on the substrate temperatures. The refractive index n, extinction coefficient k and dielectric constants ε1 and ε2 were also discussed and calculated as a function of wavelength λ. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman analysis of the quantum dot morphology
Authors: Marques G. E. , Alcalde A. M. , Ribeiro A. A. , Dantas N. O. , Trallero Giner C. 
Published: February 2007

AbstractA theoretical and experimental study of the spatial con.nement of phonons in ternary CdSx Se1–x nanocrystals embedded in a glass matrix is reported. We discuss the morphological characteristics of the nanocrystals by analyzing the dependence of surface phonon modes on the geometrical parameters. The calculated frequencies are compared with experimental Raman spectra. A good theoretical and experimental correlation for CdS‐like and CdSe‐like surface optical modes is observed. Raman selection rules and their connection with the nature of the surface optical phonons is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear excitonic absorption under an external electric field in quantum dot molecules
Authors: Bedoya M. , Camacho A. S. 
Published: February 2007

AbstractA study of the excitonic states in artificial molecules set up of two vertically coupled double quantum dots is presented. The electron and hole eigenstates are calculated for the quantum dot molecule. In particular, the coupling effect of the barrier and the consequent tunneling is analyzed following the evolution of the absorption spectra as function of the distance between the two dots. On the other hand, the role of the Coulomb correlation between the confined particles is also studied. We present results of relevant interactions in these systems and discuss how the optical properties of double quantum dots are affected by the interdot coupling, by the geometry of the dots and by an applied electric field. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coherent effects in coupled resonator optical waveguides
Authors: Yannopapas Vassilios , Kanaki Aggeliki , Boviatsis John , Paspalakis Emmanuel 
Published: February 2007

AbstractWe analyze the spontaneous emission and the probe absorption‐dispersion spectra of Γ‐type atomic systems embedded in a coupled resonator optical waveguide (CROW), where one of the atomic transitions decays spontaneously in a CROW and the other decays spontaneously in free space vacuum. We first show that double dark lines can appear in this system. We also show that the atoms become transparent at two different frequencies of a probe laser field coupled to the free space transition. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural, elastic and electronic properties of AlN: A first principles study
Authors: Çiftci Y. Ö. , Çolakoğlu K. , Deligöz E. 
Published: February 2007

AbstractThe brief results of the first‐principles ground‐state total energy calculations for aliminium nitrat (AlN) in zincblende and rocksalt structures are presented. Structural, elastic, and electronic calculations are performed using the SIESTA method with norm‐conserving pseudopotentials. The obtained results are compared with the available experimental and other theoretical data, and the agreement is, generally, quite good. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering and SEM study of bio‐conjugated core‐shell CdSe/ZnS quantum dots
Authors: Torchynska T. V. , Diaz Cano A. , Dybiec M. , Ostapenko S. , Morales Rodrigez M. , Jiménez‐Sandoval S. , Vorobiev Y. , Phelan C. , Zajac A. , Zhukov T. , Sellers T. 
Published: February 2007

AbstractCore‐shell CdSe/ZnS quantum dots are promising as bio‐luminescent markers: being conjugated to bio molecules (proteins), they serve as luminescence tags in antigen‐antibody biochemical reaction. This presents a possibility to detect, for example, the variation of the protein biomarkers to promote the early cancer diagnosis. We studied the effect of bio molecules conjugated to QDs using Raman scattering spectra, and found that in some cases the conjugation leads to noticeable variation of these spectra, so that the detection of bio molecules could be done more accurately. An explanation of the effect is proposed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface photovoltage spectroscopy of interdiffused InAs/InGaAlAs quantum dashes‐in‐well structure
Authors: Donchev V. , Ivanov Ts. , Wang Y. , Djie H. S. , Ooi B. S. 
Published: February 2007

AbstractWe report room temperature surface photovoltage (SPV) spectroscopy studies of both as‐grown and interdiffused InAs quantum dash (QD)–in–InAlGaAs quantum well (QW) structures grown by molecular beam epitaxy on (100) InP substrates. The interdiffusion is achieved by means of rapid thermal annealing at 800 ºC for 30 s. The SPV spectra reveal step‐like structures related to the optical absorption in the QDs, QWs, InGaAlAs separate carrier confinement layer, InAlAs lower cladding layer and InP substrate. The annealing results in a high‐energy shift of these spectral structures. The shift is attributed to the group‐III atoms intermixing from the thermal induced interdiffusion across the heterointerfaces. The effect of interdiffusion is larger for the elements with larger surface‐to‐volume ratio (QDs and QWs). The blue shift of the QD transition is observed also in the photoluminescence spectra. The results contribute to the optimization of the technological procedure for QD bandgap tuning via the interdiffusion technique. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum qubit measurement by a quantum point contact with a quantum Langevin equation approach
Authors: Dong Bing , Horing N. J. M. , Lei X. L. , Cui H. L. 
Published: February 2007

AbstractWe employ a microscopic quantum Heisenberg‐Langevin equation approach to establish a set of quantum Bloch equations for a two‐level system (coupled quantum dots) capacitively coupled to a quantum point contact (QPC). The resulting Bloch equations facilitate our analysis of qubit relaxation and decoherence in coupled quantum dots induced by measurement processes at arbitrary bias‐voltage and temperature. We also examine the noise spectrum of the meter output current for a symmetric qubit. These results help resolve a recent debate about a quantum oscillation peak in the noise spectrum. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)