bluuebunny/crossref_metadata_2025_split huggingface dataset:
Exfoliation of stacked sheets: Effects of temperature, platelet size, and quality of solvent by a Monte Carlo simulation
Authors: Pandey R. B. , Anderson K. L. , Farmer B. L. 
Published: November 2006

AbstractCan a layer of stacked sheets (coarse grained description of clay platelets) exfoliate in a given solvent? Computer simulations are performed to address this question with a stacked layer of four sheets. A sheet is described by a set of nodes (N) tethered together by flexible (fluctuating) bonds in a planar structure with linear scaleLs,N=Ls2on a cubic lattice of sizeL3. The initial distance between the sheets is small and kept constant for different sets of stacked sheets. Quality of the effective solvent is controlled by a short range interaction (ε) between sheets, that is, their nodes and the empty lattice sites (ε = −2,−1, 1, 2). Nodes execute stochastic movement with the Metropolis algorithm subject to bond fluctuation and excluded volume constraints. Simulations are also performed at different temperatures. Visual analysis shows that the exfoliation depends on the size of the sheet and temperature. We find that it is easier to exfoliate smaller sheets and that the exfoliation is enhanced by raising the temperature. The exfoliation becomes very slow for large sheets at low temperatures because of longer relaxation times. Exfoliation is enhanced by increasing the attractiveness (i.e., the quality) of the solvent interaction with the platelets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 3580–3589, 2006
Ferroelastic to paraelastic phase transition of K3H(SeO4)2 and Rb3H(SeO4)2 single crystals studied by nuclear magnetic resonance and external stress
Authors: Lim Ae Ran , Ham Shin Gyoon , Chang Jin‐Hae , Ichikawa M. 
Published: November 2006

AbstractThe temperature dependences of the nuclear magnetic resonance (NMR) and the stress–strain hysteresis curves have been measured for K3H(SeO4)2 and Rb3H(SeO4)2 crystals grown using the slow evaporation method. By analysis of the 39K and 87Rb NMR results, it has been confirmed that the phase below TC is ferroelastic with twin domains and that the phase above TC is paraelastic with a single domain. The ferroelastic domain switching that occurs in the two single crystals due to external stress was also studied. The critical stress values for converting the twin‐domain state to the single‐domain state were obtained. When external stresses of 0.6 and 0.4 MPa were applied to the K3H(SeO4)2 and Rb3H(SeO4)2 crystals, respectively, transitions from twin‐domain to single‐domain states were observed. The ferroelastic domain switching resulting from an external stress may be associated with the atomic rearrangements of the SeO4 tetrahedra in K3H(SeO4)2 and Rb3H(SeO4)2 crystals; the ferroelastic domain switching is explained by the restriction of the rotation of the SeO4 tetrahedra as a result of the breaking of all hydrogen bonds by the external stress. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of lead nitrate single crystals
Authors: Isoda Hiroshi , Kawashima Riki 
Published: November 2006

AbstractThe measured alternating current (ac) electrical conductivity of lead nitrate [Pb(NO3)2] crystals in the frequency range 20–106 Hz at temperature varying from 200 to 320 K shows anomalous temperature dependence, having meta‐stability in the temperature range from 240 to 300 K. The dynamic properties have been extracted from these ac electrical data. The frequency exponents derived from the power law of the conductivity exhibit a singularity in this temperature variation range. A critical slowing down has been observed at temperatures near 275 K. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and electrical properties of Sr‐modified Pb(NbMo)3 system
Authors: Rai Radheshyam , Bihari Bipin , Singh N. K. , Choudhary R. N. P. 
Published: November 2006

AbstractStrontium (Sr)‐doped (Pb1–z Srz )0.375(Nb0.75Mo0.25)O3 (PSNM), where z = 0.00, 0.03, 0.05, 0.07, has been synthesized by a solid‐solution mixing technique. Some aspects of structure of the compound at room temperature were studied using an X‐ray diffraction (XRD) technique. Dielectric studies (dielectric constant (ϵ) and dielectric loss (tan δ)) obtained both as a function of frequency (100 Hz to 100 kHz) at room temperature (RT) and temperature (RT – 500 K) at 10 kHz suggest that compounds undergo a ferroelectric–paraelectric phase transition of the diffuse type. The activation energy (Ea) of the samples was calculated from the plot of ac conductivity versus the inverse of absolute temperature. The activation energy (Ea) of all the doped compounds was found to be very low. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Tunneling spectroscopy of quantum wires: Spin‐charge separation and localization
Authors: Yacoby A. , Auslaender O. M. , Steinberg H. , Tserkovnyak Y. , Halperin B. I. , Baldwin K. W. , Pfeiffer L. N. , West K. W. 
Published: November 2006

AbstractUsing a double wire geometry we probe the quantum many‐body modes in ballistic wires and their dependence on Coulomb interactions. The wires are fabricated using the cleaved edge overgrowth method. We clearly observe two spin modes and one charge mode of the coupled wires. We map the dispersion velocities of the modes down to a critical density at which spontaneous localization is observed. Theoretical calculations of the charge velocity agree well with the data, although they also predict an additional charge mode that is not observed. Surprisingly, the suppression of the spin velocities does not depend on density. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum shot noise in edge channels
Authors: Heiblum M. 
Published: November 2006

AbstractCharge excitations under quantized magnetic field flow in one dimensional‐like strips along the edges of the sample. These excitations (quasiparticles) may behave independently (under weaker fields) or condense to an interacting chiral Luttinger liquid (under stronger fields). Adding a backscattering potential in the path of the quasiparticles, partitions them, hence inducing quantum shot noise that is proportional to their charge and is affected by their correlation. We summarize here our studies of the noise in edge states. At sufficiently low temperatures the correlations among the scattering events are strong, leading to highly non‐linear I –V characteristic and non‐classical shot noise. However, at finite temperatures and weak back scattering, quasiparticles backscatter independently, with noise proportional to e /3, e /5 and e /7 at filling factors 1/3, 2/5, and 3/7. Alternatively, at sufficiently strong backscattering induced bunching of e /3 quasiparticles takes place, with shot noise proportional to e. Diluting the impinging quasiparticles beam mimics an increased temperature, effectively weakening the correlation, rendering the quasiparticles scattering stochastic. Moreover, surprisingly, at finite temperatures (∼50 mK), highly dilute fractionally charged quasiparticle beams are found to traverse almost opaque barriers with no significant bunching. Bunching, however, takes place at lower temperatures. In the opposite case of very weak backscattering potential and at extremely low temperatures (∼9 mK), surprising bunching of quasiparticles takes place: e * = 2e /5 at filling factor 2/5 and e * close to 3e /7 at filling factor 3/7. Under the same conditions, as the temperature increases, (to 25–50 mK) bunching ceases and the scattered charge is again the familiar Laughlin's quasiparticles charge e/m. We show also the shot noise generated by an edge channel interferometer. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin ordering: two different scenarios for the single and double layer structures in the fractional and integer quantum Hall effect regimes
Authors: Dolgopolov V. T. , Deviatov E. V. , Khrapai V. S. , Reuter D. , Wieck A. D. , Wixforth A. , Campman K. L. , Gossard A. C. 
Published: November 2006

AbstractWe investigate the ground state competition at the transition from the spin unpolarized to spin ordered phase at filling factor ν =2/3 in single layer heterostructure and at ν =2 in double layer quantum well. To trace the quantum Hall phase we use the minimum in the dissipative conductivity σ xx We observe two different transition scenarios in two investigated situations. For one of them we propose a qualitative explanation, based on the domain structure evolution in the vicinity of the transition point. The origin for the second scenario, corresponding to the experimental situation at ν =2 in double layer quantum well, still remains unclear. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wannier–Stark level anticrossing in biperiodic superlattices
Authors: Coquelin M. , Pacher C. , Kast M. , Strasser G. , Gornik E. 
Published: November 2006

AbstractThe complex interplay of coherent and incoherent transmission channels in biased biperiodic superlattices is studied utilizing hot‐electron spectroscopy. It is found that coherent transport through the superlattices is dominated by the progressive localization of the Wannier–Stark states of two subminibands. This electric field dependence is lifted at special superlattice bias conditions where anticrossings between the Wannier‐Stark states of neighboring subminibands are induced. Additionally, LO‐phonon mediated transmission channels open up at electric fields where the Wannier–Stark splitting between individual states exceeds the LO‐phonon energy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recent developments in single dot coherent devices
Authors: Zrenner A. , Stufler S. , Ester P. , Michaelis de Vasconcellos S. , Hübner M. , Bichler M. 
Published: November 2006

AbstractIn the current contribution we review the physics of single quantum dot photodiodes. The coupling of a quantum system to an electric circuit allows for impressively simple and reliable single quantum measurements. The application of this concept leads to a new class of coherent optoelectronic devices with novel and so far unattained functionalities. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural parameters and transition pressures of ZnO: ab‐initio calculations
Authors: Saib S. , Bouarissa N. 
Published: November 2006

AbstractThe structural parameters of ZnO in three phases, namely wurtzite, zincblende and rocksalt as well as transition pressures from wurtzite and zincblende to rocksalt structures are presented. Besides, the elastic constants in the three considered phases are reported. The calculations are performed using an ab‐initio pseudopotential study within the framework of the density‐functional theory (DFT) with both the local density approximation (LDA) and the generalized gradient approximation (GGA). Detailed comparisons are made with published experimental and theoretical results and show generally good agreement. Moreover, in most cases the present results are improved with respect to experiment when compared with previous calculations. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Collective effects in radiation force on movable quantum dots
Authors: Iida Takuya , Ishihara Hajime 
Published: November 2006

AbstractWe theoretically study the resonant radiation force (RF) exerted on interacting quantum dots (QDs). For this purpose, the analytical expression of RF is derived based on the nonlocal theory and the Lorentz force equation. This explicitly shows how RF on QDs behaves under optical excitation of photomediated coupled‐states of polaritons in respective QDs confining excitons. In particular, if three QDs are aligned perpendicular to the optical axis, the negative dissipative (scattering and absorbing) force, whose direction is opposite to the light propagation direction, is exerted on the middle QD due to the phase inversion of the induced polarization in it. Furthermore, indirect attractive and repulsive forces arise between QDs at both ends via the middle QD. These effects would enable us to control the spatial dynamics of a QD‐assembly by exciting their collective modes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the photoconductivity of layered molecular complex of fullerene C60 with saturated amine TMPDA
Authors: Golovin Yu. I. , Lopatin D. V. , Rodaev V. V. , Konarev D. V. , Litvinov A. L. , Lyubovskaya R. N. 
Published: November 2006

AbstractIt was revealed that the photoconductivity of layered molecular complex of fullerene C60 with saturated amine TMPDA: TMPDA · C60 is caused by intermolecular electronic processes in the fullerene layers. The intermediate magneto‐sensitive stage of photogenerating free charge carriers was found to be due to the effect of magnetic field on the rate constant of the triplet charge transfer exciton annihilation process. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Attack–norm separation for detecting attack‐induced quality problems on computers and networks
Authors: Ye Nong , Chen Qiang 
Published: November 2006

AbstractCyber attacks on computer and network systems induce system quality and reliability problems, and present a significant threat to the computer and network systems that we are heavily dependent on. Cyber attack detection involves monitoring system data and detecting the attack‐induced quality and reliability problems of computer and network systems caused by cyber attacks. Usually there are ongoing normal user activities on computer and network systems when an attack occurs. As a result, the observed system data may be a mixture of attack data and normal use data (norm data). We have established a novel attack–norm separation approach to cyber attack detection that includes norm data cancelation to improve the data quality as an important part of this approach. Aiming at demonstrating the importance of norm data cancelation, this paper presents a set of data modeling and analysis techniques developed to perform norm data cancelation before applying an existing technique of anomaly detection, the chi‐square distance monitoring (CSDM), to residual data obtained after norm data cancelation for cyber attack detection. Specifically, a Markov chain model of norm data and an artificial neural network (ANN) of norm data cancelation are developed and tested. This set of techniques is compared with using CSDM alone for cyber attack detection. The results show a significant improvement of detection performance by CSDM with norm data cancelation over CSDM alone. Copyright © 2006 John Wiley & Sons, Ltd.
Cuscore control charts for generalized feedback‐control systems
Authors: Nembhard Harriet Black , Chen Shuohui 
Published: November 2006

AbstractThe cumulative score (Cuscore) statistic is devised to ‘resonate’ with deviations or signals of an expected type. When a process signal subject to feedback control occurs, it results in a fault signature in the output error. In this paper, Cuscore statistics are designed to monitor process parameters and characteristics measured by a generalized minimum variance (GMV) feedback‐control system sensitive to the fault signature of a spike, step, and bump signal. In this study, the GMV considered is a first‐order dynamic system with autoregressive moving average (ARMA) noise. We show theoretically that the performance of Cuscore charts is independent of the amount of variability transferred from the output quality characteristic to the adjustment actions in the GMV control system. Simulation is used to test the performance using the Cuscore charts. In general, the Cuscore can detect signals over a broad range of system parameter values. However, areas of low detection capability occur for certain fault signatures. In these cases, a tracking signal test is combined with the Cuscore statistics to improve detection performance. This study provides several illustrations of the underlying behavior and shows how the methodology developed can be easily applied in practice. Copyright © 2006 John Wiley & Sons, Ltd.
Winning customer loyalty in an automotive company through Six Sigma: a case study
Authors: Kumar Maneesh , Antony Jiju , Antony Frenie Jiju , Madu Christian N. 
Published: November 2006

AbstractSix Sigma is a disciplined approach to improving product, process and service quality. Since its inception at Motorola in the mid 1980s Six Sigma has evolved significantly and continues to expand to improve process performance, enhance business profitability and increase customer satisfaction. This paper presents an extensive literature review based on the experiences of both academics and practitioners on Six Sigma, followed by the application of the Define, Measure, Analyse, Improve, Control (DMAIC) problem‐solving methodology to identify the parameters causing casting defects and to control these parameters. The results of the study are based on the application of tools and techniques in the DMAIC methodology, i.e. Pareto Analysis, Measurement System Analysis, Regression Analysis and Design of Experiment. The results of the study show that the application of the Six Sigma methodology reduced casting defects and increased the process capability of the process from 0.49 to 1.28. The application of DMAIC has resulted in a significant financial impact (over U.S. $110 000 per annum) on the bottom‐line of the company. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry
Authors: Silva Eduarda M. P. , Serra Vanda Vaz , Ribeiro Anderson O. , Tomé João P. C. , Domingues Pedro , Faustino M. Amparo F. , Neves M. Graça P. M. S. , Tomé Augusto C. , Cavaleiro José A. S. , Ferrer‐Correia António J. , Iamamoto Yassuko , Domingues M. Rosário M. 
Published: November 2006

AbstractNovel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI‐MS/MS). The electrospray mass spectra (ESI‐MS) show the M+ ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI‐MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (−163 or −243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (−162 or −242 Da) and cross‐ring fragmentations typical of glyco‐derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic β‐pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C5–C6 bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI‐MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit. Copyright © 2006 John Wiley & Sons, Ltd.
Electron ionization mass spectra of phosphorus‐containing heterocycles. III. 1,3,4,2‐Oxadiazaphosphinane 2‐oxides
Authors: Juhász Márta , Zalán Zita , Fülöp Ferenc , Pihlaja Kalevi 
Published: November 2006

AbstractThe 1,3,4,2‐oxadiazaphosphinane 2‐oxides differ not only in the relative configuration of the P atom (R* or S*), but also in many other ways such as the ring size, ring fusion, P substitution and bridgehead N atom whose effects on their fragmentations have been studied. Some fragmentations resembled those of 3,1,2‐oxazaphosphinane 2‐oxides and 1,3,2‐diazaphosphinane‐2‐oxides, but new routes were also found, initiated by ionization at the bridgehead N atom. The relative abundances of the molecular ions and some fragment ions allowed the differentiation of cis‐trans epimers. Compounds with n = 2 and R  N(CH2CH2Cl)2, and linearly or angularly isoquinoline‐fused isomers in most cases, gave more numerous ions with lower relative abundances than the other compounds in this series. Only the isoquinoline derivatives provided fragments resulting from ionization of the aromatic part of the molecule. Copyright © 2006 John Wiley & Sons, Ltd.
First observation of cylindrospermopsin in Anabaena lapponica isolated from the boreal environment (Finland)
Authors: Spoof Lisa , Berg Katri A. , Rapala Jarkko , Lahti Kirsti , Lepistö Liisa , Metcalf James S. , Codd Geoffrey A. , Meriluoto Jussi 
Published: November 2006

AbstractThe cyanobacterial cytotoxin cylindrospermopsin has been mostly associated with cyanobacteria present in tropical and subtropical regions. Cylindrospermopsin has recently been found in cyanobacterial samples in central and southern Europe but the possible presence of the toxin in northern Europe has been unknown. Fifty‐eight field and laboratory culture samples of Finnish cyanobacteria were analyzed by high‐performance liquid chromatography combined with UV diode‐array detection, multiple reactant monitoring in a triple‐quadrupole mass spectrometer (MS), and accurate mass measurements using a time‐of‐flight MS instrument. Cylindrospermopsin was confirmed by all three techniques in a culture sample of Anabaena lapponica at a concentration of 242 μg cylindrospermopsin per g freeze‐dried cyanobacterial material. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 552–560, 2006.
Toxicity and modulations of biomarkers in Xenopus laevis embryos exposed to polycyclic aromatic hydrocarbons and their N‐heterocyclic derivatives
Authors: Burýšková Blanka , Hilscherová Klára , Bláha Luděk , Maršálek Blahoslav , Holoubek Ivan 
Published: November 2006

AbstractEffects of a newly identified group of organic environmental pollutants of concern (N‐heterocyclic derivatives of polycyclic aromatic hydrocarbons, NPAHs) were investigated using the 96 h FETAX (Frog Embryo Teratogenesis Assay – Xenopus). Beside standard FETAX parameters (mortality, malformations), changes in several biochemical markers were studied as early signs of intoxication. Biomarkers included determination of glutathione (GSH) levels and lipid peroxidation as well as activities of important detoxification and antioxidant enzymes (glutathione‐S‐transferase, glutathione peroxidase, glutathione reductase). 1,10‐Phenathroline was the most toxic of all tested compounds (96 h LC50 = 4 μM). All tested NPAHs induced malformations in the frog embryos. The data suggest that the exposure to NPAHs can induce oxidative stress in amphibians; most biochemical markers were modulated at concentrations lower than those resulting in significant mortality. Results document mortality and teratogenicity of all studied NPAHs to amphibian embryos while no significant mortality, teratogenicity or modulations in biochemical markers could be observed with unsubstituted polycyclic aromatic hydrocarbons (PAHs) at concentrations up to their water solubility. This information along with the significantly greater solubility and thus bioavailability compared to their nonsubstituted parent compounds suggests that NPAHs could contribute significantly to the overall aquatic toxicity of mixtures of PAHs and their derivatives. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 590–598, 2006.