bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enhanced swelling and adsorption properties of AAm‐AMPSNa/clay hydrogel nanocomposites for heavy metal ion removal
Authors: Kaşgöz Hasine , Durmuş Ali , Kaşgöz Ahmet 
Published: October 2007

AbstractNovel type hydrogel‐clay nanocomposites based on the acrylamide (AAm)‐ 2‐acrylamido‐ 2‐methylpropane sulfonic acid (AMPS) sodium salt and clay were synthesized via in situ copolymerization in aqueous solution. Samples were characterized by determining total basic group (TGB) content and swelling degree, XRD analysis, and FTIR spectroscopy. Effects of monomer ratio and clay amount on the swelling properties of the samples were investigated. It was found that the hydrogel/clay nanocomposites exhibited improved swelling capacity compared with the hydrogels. Samples were used to remove heavy metal ions (Cu (II), Cd (II), and Pb (II)) from aqueous solution in competitive and non‐competitive conditions for the first time. The effects of time and pH of the initial metal ion solution on the adsorption capacity were investigated and selectivity properties of the samples were evaluated. It was found that incorporation of a low amount of clay (10% (wt)) into the polymer structure increased the heavy metal ion adsorption capacity of the sample. It was concluded that the AAm‐AMPS/clay nanocomposites could be used as novel type, fast‐responsive, and high capacity sorbent materials in heavy metal removing processes. Copyright © 2007 John Wiley & Sons, Ltd.
Immune‐compromised state in the rat pancreas after chronic alcohol exposure: the role of peroxisome proliferator‐activated receptor γ
Authors: Fortunato F , Berger I , Gross M‐L , Rieger P , Buechler MW , Werner J 
Published: October 2007

AbstractAlcohol exposure is known to sensitize acinar cells to various insults but the pathophysiological mechanisms of alcoholic pancreatitis remain unknown. Alcohol abuse has been shown to mediate an anti‐inflammatory response and periods of immune suppression seem to be associated with organ injury and mortality. The purpose of this study was to determine the mechanisms by which alcohol exerts transcriptional activities in the rat pancreas and how alcohol alters the inflammatory response. Using the Lieber–DeCarli alcohol/control diet, rats that were fed with alcohol over 14 weeks demonstrated a decrease of inflammatory cells in pancreatic tissue compared to controls. The anti‐inflammatory effects of alcohol were confirmed by decreased expression of pro‐inflammatory cytokines including TNFα, IL‐1β, IL‐18, TGFβ, and MCP‐1. In addition, alcohol significantly increased the activity of PPARγ, which is a known anti‐inflammatory transcription factor, while pro‐inflammatory factors including AP‐2 and EGR‐1 were significantly suppressed. NFκB binding showed a tendency towards a reduction. Electron microscopy studies revealed enlarged and injured mitochondria and lysosomes, accompanied by peri‐cellular fibrosis. Furthermore, alcohol exposure increased the activities of trypsin and cathepsin B, both known to be critical in initiating acinar cell injury and pancreatitis. Despite the known alcohol‐mediated acinar cell and mitochondrial injury, the mitochondrial‐mediated apoptotic pathway was attenuated. These data demonstrate that the pancreas exposed to alcohol maintains an anti‐inflammatory state by activating PPARγ. Intracellular mitochondrial and lysosomal damage after chronic alcohol exposure induces premature activation of digestive enzymes and establishment of peri‐cellular fibrosis in the absence of inflammation. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Detection of high‐mobility group proteins A1 and A2 represents a valid diagnostic marker in post‐pubertal testicular germ cell tumours
Authors: Franco R , Esposito F , Fedele M , Liguori G , Pierantoni GM , Botti G , Tramontano D , Fusco A , Chieffi P 
Published: October 2007

AbstractThe high‐mobility group A (HMGA) non‐histone chromosomal proteins HMGA1 and HMGA2 are architectural factors. They are abundantly expressed during embryogenesis and in most malignant neoplasias, whereas their expression is low or absent in normal adult tissues. Their over‐expression is known to have a causal role in cellular neoplastic transformation. Previous studies from our group have shown that their expression is restricted to specific germinal cells. In this study we have evaluated, by immunohistochemistry, the expression of HMGA1 and HMGA2 in a series of post‐pubertal testicular tumours of different histological types, including 30 seminomas, 15 teratomas, 15 embryonal carcinomas and 10 mixed germinal tumours with a prominent yolk sac tumour component. HMGA1 protein expression was detected in all seminomas and embryonal carcinomas analysed, but not in teratomas or yolk sac carcinomas. Conversely, HMGA2 was present only in embryonal carcinomas and yolk sac carcinomas, but not in seminomas or teratomas. The immunohistochemical data were further confirmed by Western blot and, at the mRNA level, by RT–PCR analyses. These findings indicate that HMGA1 and HMGA2 are differently expressed with respect to the state of differentiation of testicular germ cell tumours (TGCTs), with over‐expression of both proteins in pluripotential embryonal carcinoma cells and loss of expression of HMGA1 in yolk sac tumours and of both proteins in the mature adult tissue of teratoma areas. Therefore, the different profiles of HMGA1 and HMGA2 protein expression could represent a valuable diagnostic tool in some cases in which the histological differential diagnosis is problematic. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Management of menopausal symptoms: the risks and benefits
Authors: Currie Heather , Guttinger Anja 
Published: October 2007

AbstractDespite recent controversy, hormone replacement therapy remains the mainstay of treatment of menopausal symptoms. Our Drug review considers the risks and benefits of the current treatment options, followed by sources of further information, an analysis of prescription data and the Datafile. Copyright © 2007 Wiley Interface Ltd
Clenil Modulite, a CFC‐free MDI with no adjustment on switching
Authors: Chaplin Steve , Head Steve 
Published: October 2007

AbstractClenil Modulite is the first CFC‐free metered‐dose inhaler directly interchangeable with existing CFC‐containing inhalers. In our New products review, Steve Chaplin presents the clinical data relating to its bioequivalence and Dr Steve Head comments on its place in treatment. Copyright © 2007 Wiley Interface Ltd
Elastic‐constant systematics in f.c.c. metals, including lanthanides–actinides
Authors: Ledbetter Hassel , Migliori Albert 
Published: October 2007

AbstractFor f.c.c. metals, using Blackman's diagram of dimensionless elastic‐constant ratios, we consider the systematics of physical properties and interatomic bonding. We focus especially on the lanthanides–actinides La, Ce, Yb, Th, U, Pu, those for which we know some monocrystal elastic constants. Their behavior differs from the other f.c.c. metals, and all except La show a negative Cauchy pressure, contrary to most f.c.c. metals, which show a positive Cauchy pressure. Among the lanthanides–actinides, δ‐Pu stands apart, consistent with its many odd physical properties. Based on elastic‐constant correlations, we suggest that δ‐Pu possesses a strong s‐electron interatomic‐bonding component together with a covalent component. Elastically, δ‐Pu shows properties similar to Yb. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Combined resonance and resonant detection of modulated terahertz radiation in a micromachined high‐electron mobility transistor
Authors: Hu Yabo , Ryzhii Maxim , Hagiwara Ichiro , Shur Michael S. , Ryzhii Victor 
Published: October 2007

AbstractWe analyze the operation of a resonant detector of modulated terahertz (THz) radiation based on a micromachined high‐electron mobility transistor (HEMT) with a microcantilever (MC) as mechanically floating gate. Using the device model, which describes both MC mechanical motion and plasma effects in the HEMT twodimensional electron channel, we calculate the output gate and source‐drain ac currents and the detector responsivity as functions of the modulation and carrier frequencies in linear and saturation regimes of the HEMT operation. It is shown that the THz detector responsivity exhibit sharp and high maxima under the conditions of both mechanical and plasma resonances. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coulomb‐mediated electron bunching in tunneling through coupled quantum dots
Authors: Kiesslich G. , Schöll E. , Hohls F. , Haug R. J. 
Published: October 2007

AbstractThe recent observation of super‐Poissonian shot noise in the tunneling current through two layers of selfassembled quantum dots is analyzed and discussed in terms of a sequential tunneling model for a single weakly coupled quantum dot stack.We demonstrate that the phenomenon of bunching in the electron transfer can be explained by the sole effect of Coulomb interaction between electrons inside the stack. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin‐Hall effect and spin coherent waves in semiconductors with Rashba spin‐orbit interaction
Authors: Kleinert P. , Bryksin V. V. 
Published: October 2007

AbstractBased on rigorous quantum‐kinetic equations for the spin‐density matrix, spin‐charge coupled drift‐diffusion equations are derived for a strongly confined twodimensional hole gas. An electric field leads to a coupling between the spin and charge degrees of freedom. For weak spin‐orbit interaction, this coupling gives rise to the intrinsic spin‐Hall effect that occurs in the diffusive regime. There exists a threshold value of the spin‐orbit coupling constant that separates spin diffusion from ballistic spin transport. In the latter regime, undamped spin‐coherent oscillations are observed. Their relationship to the zitterbewegung is discussed. The analytic results are compared with an exact microscopic approach valid in the ballistic regime. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum Fermi's golden rule for semiconductor nanodevices
Authors: Rossi Fausto 
Published: October 2007

AbstractWe shall revisit the conventional adiabatic or Markov approximation, stressing its intrinsic failure in describing the proper quantum‐mechanical evolution of a generic subsystem interacting with its environment. In particular, we shall show that – contrary to the semiclassical case – the Markov limit does not preserve the positivedefinite character of the corresponding density matrix, thus leading to highly non‐physical results. To overcome this problem, we shall propose an alternative adiabatic procedure which (i) in the semiclassical limit reduces to the standard Fermi's golden rule, and (ii) describes a genuine Limblad evolution, thus providing a reliable/robust treatment of energy‐dissipation and dephasing processes in electronic quantum devices. Compared to standard master‐equation formulations, the proposed approach does not involve/require any reduction or average procedure, exactly as for the derivation of the well known Fermi's golden rule. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of optical excitation in quantum dots by circularly polarized light
Authors: Ishikawa T. , Eto M. 
Published: October 2007

AbstractWe study theoretically electron states in quantum dots and their excitations by circularly polarized light. First, we calculate the hole states in a quantum dot modeled by three‐dimensional harmonic confinement potential. In the bulk direct‐gap semiconductors, the k · p perturbation method around Γ point adequately yields heavy‐hole, light‐hole and split‐off bands. We adopt the effective‐mass approximation based on the k · p perturbation method and obtain quantized energy levels for holes in the quantum dot. The ground levels are two‐fold degenerate and mainly consist of |j, m 〉 = |3/2, ±3/2〉 components. It should be mentioned that a small amount of |3/2, ±1/2〉 components are coherently mixed in the states. Second, we examine an electron‐hole excitation by the irradiation of circularly polarized light σ–. The main component of the exciton is |3/2, ‐3/2〉 hole|1/2, ‐1/2〉electron. The electron state|1/2, 1/2〉electron is also excited owing to the mixture between |3/2, ±3/2〉 and |3/2, ±1/2〉 components in the hole states, which should lead to an inaccuracy in the manipulation of electron spins. The Overhauser field created by nuclear spins plays a role when it is larger than an external magnetic field. It randomizes the direction of electron spins excited by the circularly polarized light σ‐ in an ensemble of self‐assembled quantum dots. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of decoherence in 1D systems, a comparison between distinguishable‐ and indistinguishable‐particle collisions
Authors: Buscemi Fabrizio , Bordone Paolo , Bertoni Andrea 
Published: October 2007

AbstractWe give a quantitative evaluation of the entanglement dynamics in scattering events between two electrons interacting via Coulomb potential in 1D systems, We apply a method, specifically designed for indistinguishable particles, based on the calculation of the von Neumann entropy of the system density matrix. From the timedependent numerical solution of the two‐particle wavefunction we evaluate the entanglement evolution for different spin configurations. The procedure allows to understand the mechanisms that govern entanglement creation and its connection with the characteristic physical parameters and initial conditions of the system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cutoff frequency characteristics of gate‐controlled hot‐electron transistors by Monte Carlo simulation
Authors: Igarashi Mitsuhiko , Furuya Kazuhito , Miyamoto Yasuyuki 
Published: October 2007

AbstractThe high‐speed characteristics and off characteristics of a novel transistor with a hot‐electron launcher and a transit layer of an intrinsic semiconductor whose current is controlled by an insulated gate are evaluated by Monte Carlo simulation. The dependences of the cutoff frequencyfTon the gate insulator thickness, collector bias voltage, gate length and transit layer length are clarified. For the optimum structure consisting of InP/InGaAs/W as the emitter/transit layer/collector, Au as the gate and bisbenzocyclobutene (BCB) as the gate insulator and the surrounding material,fTis 1.4 THz at the collector current density of 1.6 MA/cm2. The collector current can be controlled over four orders of magnitude by a gate voltage swing of 0.6 V. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo analysis of memory effects in nano‐scale rectifying diodes
Authors: Iñiguez‐de‐la‐Torre I. , González T. , Pardo D. , Mateos J. 
Published: October 2007

AbstractWe analyze hysteresis effects taking place for certain bias conditions in nano‐scale rectifying diodes as a consequence of the variation of the surface states occupation at the sidewalls of the trenches etched to define the channel. Such effects can be used for memory purposes. A model for the storage/release of surface charges is proposed and, implemented in a Monte Carlo (MC) simulator, is able to provide a microscopic interpretation of this effect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo simulation of plasma oscillations in ultra‐thin layers
Authors: Millithaler J.‐F. , Varani L. , Palermo C. , Pousset J. , Knap W. , Mateos J. , González T. , Perez S. , Pardo D. , Reggiani L. 
Published: October 2007

AbstractWe investigate the dispersion of the plasma frequency associated with the free carriers in a InGaAs layer of length L in the range 0.1‐1 μm as a function of the thickness W and carrier concentration at thermal equilibrium T = 300 K. To this purpose we use a Monte Carlo simulator coupled with a two dimensional Poisson solver. To take into account the fringing effects of the electric field, the layer is embedded in a dielectric medium (vacuum) along the transverse direction. The fluctuations of the voltage at the center of the sample are extracted and their spectral density calculated by Fourier transform of their autocorrelation function.For W = 100 nm and carrier concentrations of 1016 ÷ 1018 cm–3 the spectral density shows peaks which are in good agreement with the 3D expression of the plasma frequency. For W ≤ 10 nm the spectral density of voltage fluctuations exhibits a peak that depends on L, thus implying that the oscillation mode exhibits a dispersion. The corresponding frequency values are in good agreement with the 2D expression of the plasma frequency obtained for a ballistic regime within the in‐plane approximation for the electric field. Simulations evidence a region of cross‐over between the 2D and 3D plasma frequencies for width W around 20 nm. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coherent control of carrier capture and wave front dynamics in homogeneously excited quantum wire‐dot systems
Authors: Kuhn Tilmann , Reiter Doris , Axt Vollrath Martin 
Published: October 2007

AbstractWe study the coherent control of capture and transport processes in a quantum wire‐quantum dot‐system which is homogeneously excited by ultrafast laser pulses. Due to the carrier capture into the quantum dot a spatial profile of the carrier density in the wire region builds up exhibiting wave fronts moving away from the dot. In the presence of a dot with two or more bound levels wave fronts resulting from the capture into different states can clearly be distinguished. By using a pair of phase locked pulses the capture rates into different levels but also the spatio‐temporal dynamics in the wire region can be coherently controlled. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Monte Carlo investigation of carrier transport in fabricated back‐to‐back Schottky diodes: Influence of direct quantum tunnelling and temperature
Authors: Pascual E. , Rengel R. , Reckinger N. , Tang X. , Bayot V. , Dubois E. , Martín M. J. 
Published: October 2007

AbstractIn this paper we present a Monte Carlo investigation of charge transport‐including quantum tunnelling effects in fabricated back‐to‐back n‐type Schottky barriers in the reverse bias regime. The effect of the variation of the temperature over the current density and over different internal magnitudes like carrier density, electric field, etc. together with velocity distribution functions and the density of scattering mechanisms has been analyzed. The study of transport in the space charge region evidences important quasi‐ballistic characteristics, thus becoming an important issue to be tackled in the modelling of Schottky‐based devices with reverse biased junctions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extended time delayed feedback control of stochastic dynamics in a resonant tunneling diode
Authors: Schöll E. , Majer N. , Stegemann G. 
Published: October 2007

AbstractWe investigate the influence of extended time delayed feedback upon the spatio‐temporal current density patterns in a double barrier resonant tunnelling diode. The parameters of the device are chosen to reflect a situation where the only stable state of the system is a spatially inhomogeneous ”filamentary” steady state. The addition of weak Gaussian white noise to the system gives rise to spatially inhomogeneous self‐sustained temporal oscillations that can be quite coherent. Applying a single time delayed feedback can either increase or decrease the regularity of the noise‐induced spatio‐temporal dynamics. In this work we show that using multiple time delayed feedback provides means to increase the temporal regularity even further and to enlarge the parameter regime in which no delay‐induced bifurcations occur. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Control of noise‐induced spatiotemporal patterns in superlattices
Authors: Hizanidis Johanne , Schöll Eckehard 
Published: October 2007

AbstractWe investigate a semiconductor superlattice exhibiting complex dynamics of electron accumulation and depletion fronts (travelling field domains) in the presence of noise and control. In the uncontrolled system noise is able to induce electron charge front motion through the device when the system is prepared near a global bifurcation which yields it highly sensitive to fluctuations. The associated current density oscillations exhibit a maximum of coherence at an optimal noise intensity, a phenomenon known as coherence resonance. We show how control in the form of a time‐delayed feedback signal affects the noise‐induced dynamics. We observe that control induces a limit cycle in a wide range of the control parameter space and therefore destroys the effect of coherence resonance. For low noise intensity, time‐delayed feedback control enhances the regularity (coherence) of the noisy oscillations considerably. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monte Carlo study of 2D electron gas transport including Pauli exclusion principle in highly doped silicon
Authors: Carosella F. , Saint‐Martin J. , Bournel A. , Galdin‐Retailleau S. , Dollfus P. 
Published: October 2007

AbstractA Multi Sub‐band Monte Carlo Simulator improved to efficiently include the Pauli Exclusion Principle is presented. It is used to study the transport in highly doped and ultra‐thin silicon film. Both steady state and transient regime of transport for silicon films under uniform driving field are investigated. Such approach aims to be carried out in a full device simulator to improve the modeling of the access region of nano‐Double Gate MOSFETs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamics of microwave‐induced processes in photoexcited GaAs/AlGaAs heterostructures
Authors: Baskin I. , Ashkinadze B. M. , Cohen E. , Pfeiffer L. N. 
Published: October 2007

AbstractPhotoluminescence (PL) of high‐quality GaAs/AlGaAs–based heterostructures (HS) shows a remarkable time‐dependent response to microwave irradiation pulses at temperature 2 K. The mw‐frequency was 36 GHz and the modulation pulse widths varied in a wide range. Sharp PL intensity flashes (reaching 100 fold enhancement) at the leading or/and trailing mw‐pulse edges are observed. The transient PL response exhibits a complex interplay of various mw‐induced physical processes: electron heating, electron and exciton density changes as well as an interaction of electrons, holes and excitons with non‐equilibrium acoustic phonons that are emitted by the mw‐heated 2DEG. It is noted that in commonly studied cw, mw‐induced PL (or resistivity) modulation, the observed (cw) effects are determined by a combination of these processes. We developed a model that considers the instantaneous mw‐induced electron heating and following relaxation of the photoexcited electrons, excitons and acoustic phonon flux. Using this model we simulate various types of mw‐induced PL transients observed in undoped HS's as well as in HS's that contain a 2DEG. These simulations prove that non‐equilibrium acoustic phonons play an important role in the mw‐induced PL dynamics. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quantum non‐locality in systems with open boundaries: From the Wigner‐function formalism to non‐homogeneous Markovian master equations
Authors: Taj David , Rossi Fausto 
Published: October 2007

AbstractWe shall discuss the role of electrical contacts within the conventional treatment of quantum devices based on the Wigner‐Function formalism. Our analysis will show that the artificial spatial separation between device active region and external reservoirs, being intrinsically incompatible with the non‐local character of quantum mechanics, may produce highly non‐physical results like boundary‐driven negative probability distributions.To overcome this serious limitation, we shall propose a new strategy to properly separate device and reservoir degrees of freedom, based on the well known projection techniques used in the formal theory of open systems. Our main result is a non‐Markovian master equation, where dissipation and dephasing phenomena are also induced by the presence of spatially external particle reservoirs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)