bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time‐resolved photoluminescence and steady‐state optical studies of GaInNAs and GaInAs single quantum wells
Authors: Sun Y. , Lombez L. , Braun P. F. , Ulug B. , Ulug A. , Yilmaz M. , Balkan N. , Marie X. , Carrere H. , Arnoult A. 
Published: February 2007

AbstractTime‐resolved photoluminescence spectroscopy is used to investigate carrier dynamics of Ga1–xInxNyAs1–y (x ∼ 0.33, y ∼ 0.01) single quantum well (QW) structures. PL spectra measured as a function of temperature together with the PL decay times at wavelengths around and below the PL peak energy are used to determine de‐trapping activation energies and time constants. The results are interpreted in terms of simultaneous thermal excitation of deep localized excitons to shallow localized states. According to the model, with increasing temperatures, localized excitons gain enough thermal energy to populate the free exciton states in quantum well with shorter lifetimes due to coherent nature of free excitons. In addition, at temperatures around and above 80 K, more non‐radiative channels become available to compete with the radiative processes leading to shorter time constants. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin polarised properties of optically injected VCSELs
Authors: Homayounfar A. , Adams M. J. 
Published: February 2007

AbstractThe effects of external optical injection taking account of polarisation and electron spin dynamics in vertical‐cavity surface‐emitting lasers at values of pumping close to threshold are discussed. The stability map inside and outside the locking bandwidth is given in terms of elliptical and linear polarised phenomena. Finally quasi‐periodicity in terms of two carrier densities and polarised fields is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of pH on the formation of host‐guest type material: zinc‐aluminium‐layered double hydroxide‐4‐chlorophenoxy acetate nanocomposite
Authors: Zobir Hussein Mohd , Halimah Sarijo Siti , Hj Yahaya Asmah , Zainal Zulkarnain 
Published: February 2007

AbstractLayered organic‐inorganic hybrid nanocomposite material containing 4‐chlorophenoxy acetate (4‐CPA) in an inorganic interlayer was prepared using 4‐CPA as guest anion in Zn‐Al layered double hydroxide inorganic host by direct precipitation method at various pHs. A well‐ordered nanolayered organic‐inorganic hybrid nanocomposite, with the expansion of the basal spacing from 8.9 Å in the layered double hydroxide to 19.5‐20.1 Å were obtained. The nanocomposites show that they are of mesoporous‐type with the percentage of 4‐CPA intercalated of around 35–39% (w/w) and the Zn to Al molar ratio of 3.5‐4.0. Generally, as the pH of the mother liquor increased, the Zn to Al molar ratio in the resulting nanocomposites is also increased, but the percentage of 4‐CPA intercalated and the BET surface area, decreased. This shows that the pH of the mother liquor plays an important role in determining the resulting physicochemical properties of the synthesized materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interplay of acoustic phonons and Overhauser interaction in spin blockade removal in double quantum dots
Authors: Iñarrea Jesús , Platero Gloria , MacDonald Allan H. 
Published: February 2007

AbstractThe electronandnuclei spindynamics andtheir interplaydue tothe Hyperfine interactionare self‐consistently analyzed within the framework of the density matrix formalism. Our results indicate that the current leakage experimentally observed in the spin‐blockade region of the current‐voltage curve, occurs due to spin‐flip processes induced by hyperfine interaction. A microscopical model for this interaction is presented. Our model includes a self‐consistent description of inelastic transitions where the energy is exchanged through interactions with acoustic phonons in the environment. We show as well how a magnetic field applied parallel to the current allows excited states to participate in the electronic current and removes spin blockade. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structures of finite double‐walled carbon nanotubes
Authors: Lee C. H. , Ho Y. H. , Chen R. B. , Li T. S. , Lin M. F. 
Published: February 2007

AbstractElectronic properties of finite double‐walled carbon nanotubes are calculated in the tight‐binding model. Energy levels, energy gap, and the density of states strongly depend on the symmetry configurations, the nanotube length, and the transverse electric field. The intertube interactions change the level spacing, modify the energy gap, and destroy state symmetry about the Fermi level. The transverse electric field induces state crossing, destruction of state degeneracy, increase of low‐energy states, and strong modulation of energy gap. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Golden rules for coherent transport relaxation rates in semiconductor superlattices in the field‐induced localization regime
Authors: Minot Christophe 
Published: February 2007

AbstractCoherence decay rates are derived from first principles in electronic systems the quantum states of which are localized by an electric field. The decay rates are written down as golden rules in which the transition matrix elements and the energy conservation relations involve different quantum states. A numerical evaluation is carried out in GaAs/Al0.3Ga0.7As superlattices for the electron‐LO phonon interaction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and dielectric studies on nanoparticles and atomically‐engineered surfaces of superparaelectric SrTiO3
Authors: Mochizuki Shosuke , Fujishiro Fumito 
Published: February 2007

AbstractIn order to find useful surface properties of SrTiO3 (STO) crystal, the photoluminescence and dielectric properties of STO nanoparticles and STO bulk single crystal with nanometer steps have been measured at different temperatures. The obtained results are compared with those obtained for STO bulk single crystal. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoreflectance and contactless electroreflectance of an InAs quantum dash laser structure
Authors: Motyka M. , Rudno‐Rudziński W. , Sęk G. , Kudrawiec R. , Misiewicz J. , Somers A. , Schwertberger R. , Reithmaier J. P. , Forchel A. 
Published: February 2007

AbstractPhotoreflectance (PR) and contactless electroreflectance (CER) spectroscopies have been used to study optical transitions in an InP‐based laser structure emitted at 1.55 μm with the active region including InAs quantum dashes (QDashes). Optical transitions related to all relevant parts of the structure, i.e. In0.53Ga0.05Al0.42As n‐ and p‐type cladding layers, quaternary In0.53Ga0.23Al0.24As QDash barrier layers, InGaAlAs‐GRINSCH region, and InAs QDashes have been clearly observed at room temperature. Moreover, it has been found that some of the transitions are not observable in CER spectra whereas they are very strong in PR spectra. This phenomenon is associated with different modulation mechanisms in the two electromodulation techniques. It means that the combination of PR and CER techniques with traditional photoluminescence measurements allows much better characterization of the electronic structure for semiconductor devices. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MBE growth of vertically ordered Ge quantum dots on Si
Authors: Nikiforov A. I. , Ulyanov V. V. , Teys S. A. , Gutakovsky A. K. , Pchelyakov O. P. , Yakimov A. I. , Fonseca A. , Leitão J. P. , Sobolev N. A. 
Published: February 2007

AbstractThe in plane lattice constant of the silicon film on germanium is shown to alter as the film grows; the changes reflect the process of strains relaxation of that result from the misfit of the Ge and Si lattice constants. The thickness allowing detection of changes in the in plane lattice constant of the Si film during the growth on the Ge surface depends on the germanium layer thickness. The thickness of the silicon film where elastic relaxation is determined as dependent on the germanium layer thickness. TEM studies indicate the vertical ordering of the germanium island layers when the thickness of the Si layer in between Ge layers is not sufficient to provide the full strain relaxation. The vertical ordering of Ge islands in the multilayer structure results in a decrease in the island density at reduced dispersion of their shape and size. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spin polarized and degenerate tunneling spectra in intrinsic Josephson junctions of Bi2212
Authors: Ozdemir M. , Ozyuzer L. , Kurter C. 
Published: February 2007

AbstractTunneling characteristics of HgBr2 intercalated superconducting Bi2212 single crystals have been obtained by using 10 x 10 mm2 intrinsic Josephson junction stacks, so called mesa structures. The spin degenerate current is driven along the c‐axis with Au layer using point contact tunneling assembly at 4.2 K. The spin polarized current is also driven along the c‐axis of crystals with Au/Co/Au multilayer. In order to understand the role of ferromagnetic layer (Co), quasiparticle branches are examined with and without magnetic field. The magnetic field evolution of switching currents are obtained for gaining further insight about the spin injection through the stack. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of carbon produced by methane pulsed discharge
Authors: Musa Geavit , Ekem Naci , Akan Tamer , Pat Suat , Zafer Balbag M. , Ilker Cenik M. , Vladoiu Rodica , Tanisli Murat , Ozen Ozlem 
Published: February 2007

AbstractPulsed discharges of methane gas at atmospheric pressure were generated using high voltage power supply (20 kV–25 kHz) to produce the carbon. The pulsed discharge of methane gas was generated between two sharp wolfram electrodes. It brings out carbon and acetylene and other hydrocarbons at the same time. In this study, carbon samples are produced and some of the physical properties of them were analyzed. The production rate of carbon was also determined. Carbon samples were investigated by Scanning Electron Microscopy, Energy Dispersive X‐ray spectroscopy and X‐ray diffraction. The produced carbon samples have amorphous structure according to XRD results and include no contamination according to EDX results. The samples have the strongest peak at 26.516° at XRD spectra. Production rate is 0.52 mg/min at d (discharge space) being 8 mm and (flux of the methane gas) ϕ is 0.3 l/min. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling effects on electron‐phonon scattering in double quantum dots
Authors: Ramirez H. Y. , Camacho A. S. , Lew Yan Voon L. C. 
Published: February 2007

AbstractIn this work we study the electron‐phonon interaction in GaAs/AlGaAs double‐dot systems for cylindrical and spherical geometries with finite confinement, coupled by a tunnelling barrier and an external dc electric field. The eigenenenergies and envelope wave functions are numerically obtained for different values of the external bias. We study the effects of field and the dots‐shape on the relaxation rates of electronic transitions between double‐dot states by electron‐acoustic phonon and electron‐optical phonon interaction. We found the piezoelectric interaction to be small compared with the deformation potential one, and the spherical more convenient than the cylindrical geometry to reduce the electron‐phonon decay rates. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Interference effects on Andreev reflection through double quantum dots
Authors: Tanaka Yoichi , Kawakami Norio 
Published: February 2007

AbstractWe study transport through double quantum dots (DQD) coupled to normal and superconducting leads. Especially, we focus on the interplay between the Andreev reflection and the interference effect, which occurs in a parallel DQD but not in a serial DQD system. In the parallel DQD system, it is elucidated that the differential conductance has Fano‐type dip structures in addition to four peaks, which are caused by the interference between the distinct transport channels via Andreev bound states. We further discuss a T‐shaped DQD system, which is another typical system sensitive to the interference effect. In this system, we find that the shift of the dot energy‐level gives rise to intriguing properties in the conductance. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Localization of electrons in type‐II Ge/Si quantum dots stacked in a multilayer structure
Authors: Yakimov A. I. , Nikiforov A. I. , Dvurechenskii A. V. , Bloshkin A. A. 
Published: February 2007

AbstractSpace‐charge spectroscopy was employed to study electronic structure of a single layer of Ge quantum dots and of a stack of four layers of Ge islands embedded in an n ‐type Si(001) matrix. For a multilayer sample, the evidence for an electron localization in strained Si in the vicinity of Ge dots was found. From the temperature‐ and frequency‐dependent measurements the electron binding energy was determined to be 40–70 meV for different quantum states. The electron accumulation was not observed in a sample with a single layer of Ge dots. Existence of localized electronic states is explained by a modification of the conduction band alignment induced by inhomogeneous tensile strain in Si around the buried Ge dots. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Light scattering in an electron‐hole double quantum well in the presence of spin‐orbit interaction
Authors: Yang C. H. , Zhang C. , Xu Wen , Zeng Z. 
Published: February 2007

AbstractIn this work, we study theoretically the lineshape and intensity of light scattering in an electron‐hole double quantum well structure in the presence of spin‐orbit interaction (SOI). Using the random phase approximation and Green function approach, the dispersion and the excitation spectra in this structure have been calculated. It is shown that scattering intensity can be tuned by the spin‐orbit (SO) couple via the applied electrical field. The peaks shift as the polarization of electron or hole increases. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of a biodegradable foam for protective packaging applications
Authors: Arif Samina , Burgess Gary , Narayan Ramani , Harte Bruce 
Published: February 2007

AbstractGreen Cell® foam (GCF) is a biodegradable foam packaging material produced from a proprietary cornstarch blend. It is commercially available in a variety of laminations and constructions. Cushioning ability and thermal resistance (R‐value) are the fundamental properties needed to compete against synthetic foams. Since GCF is starch based and biodegradable, a concern was that moisture would likely affect its physical properties. Cushioning characteristics and insulation R‐values of 1 and 2 inch foams were determined as a function of temperature and moisture content. The ASTM method D1596 was used to determine the cushioning properties and an ice melt test was used to determine the thermal resistance. Moisture sorption isotherms were developed at three temperatures (20, 25 and 30°C) to determine its moisture sensitivity. The 1‐inch‐thick foam had lower G values at lower static stresses than synthetic foams, but had higher G values at higher static stresses. The 2‐inch‐foam had G values similar to that of synthetic foam materials. Dimensional changes were observed at higher relative humidity (RH) conditions, especially at 30°C. The R‐values at higher humidities were also less than that of synthetic materials. Copyright © 2007 John Wiley & Sons, Ltd.
Zur Problematik der Zwischenbewitterung von Epoxidharz‐Teil beschichtungen an Brückenbauwerken
Authors: Gelhaar Andreas , Schneider Andreas 
Published: February 2007

AbstractFür den Korrosionsschutz von Brückenbauwerken kommen aufgrund der geforderten langen Schutzdauer überwiegend zweikomponentige Beschichtungssysteme auf Basis von Epoxidharz/Polyurethan nach Blatt 87 der TL/TP‐KOR‐Stahlbauten zum Einsatz. Bei der meistens praktizierten Aufteilung des Gesamtsystems in Werkstatt‐ und Baustellenbeschichtung kann es durch Zwischenbewitterung der Epoxidharz‐Teil beschichtung zu Verbundproblemen kommen, was bereits zu Schadensfällen geführt hat. Der Beitrag beinhaltet Untersuchungsergebnisse zu dieser Problematik an in Nutzung befindlichen Bauwerken und berichtet über Erkenntnisse, die beim Brückenneubau bei dem Anlegen von Probebeschichtungen auf unterschiedlich vorbereiteten Oberflächen gewonnen wurden. Aus den Ergebnissen werden Schlußfolgerungen und Empfehlungen zur weiteren Verfahrensweise abgeleitet.
Discernment of relative retention values of triglyceride α,β isomers on reverse phase high performance liquid chromatography
Authors: Kinoshita Kuninori , Kimura Minoru , Takahashi Koretaro , Zama Koichi 
Published: February 2007

AbstractDiscernment of α,β isomers of triglyceride on reverse phase high performance liquid chromatography (HPLC) was investigated by the use of a multiple regression analysis. The retention effect of triglyceride molecular species was considered to be dependent principally on the addition theorem of chemical potential of both position α and position β (acyl carbon numbers and numbers of double bonds in the acyl group), though it was observed that the retention effect of position α is somewhat larger than that of position β on HPLC when it has the same acyl group combination.
Conductometric investigations on lanthanum soap solutions
Authors: Mehrotra K. N. , Gahlaut A. S. , Sharma Meera 
Published: February 2007

AbstractThe critical micelle concentration (CMC), degree of dissociation and dissociation constant of lanthanum caprate in benzene‐methanol mixtures of varying composition were determined using conductometric measurements. The results show that the soap behaves as a weak electrolyte in these solutions below the CMC. The value of the CMC (0.0027 M) was found to be independent of the solvent composition but increases with the addition of dye.
Phase investigations of fats. II. Systems containing oleic and stearic acids and an organic solvent
Authors: Singleton W. S. 
Published: February 2007

Summary

The ternary systems oleic acid‐stearic acid‐commercial hexane and oleic acid‐stearic acid‐acetone containing varying amounts of the three components have been equilibrated at 0°C., −10°C., −20°C., −30°C., and −40°C.

From compositional data of the liquid and solid phases in equilibrium at each isotherm, ternary phase diagrams have been constructed. From these diagrams it is possible to predict the degree of separation which can be obtained with any given mixture of oleic and stearic acids, using either acetone or commercial hexane as solvent.

With practical solvent ratios the phase diagrams at −20°C., −30°C., and −40°C., exhibit closed areas representing liquid phase composition. The liquid phase boundaries have been established for each isotherm investigated.

The intersolubilizing effect of oleic acid on stearic acid, greater in commercial hexane than in acetone, and the possible formation of mixed crystals of oleic and stearic acid have been noted.

Oleic acid of high purity can be obtained as one of the practical applications of these data.
Note on the hygroscopic equilibrium of cottonseed and cottonseed products
Authors: Karon M. L. , Adams Mabelle E. 
Published: February 2007

Summary and ConclusionsThe hygroscopic equilibrium of a sample of the Stoneville 2B variety of cottonseed and its derived products has been determined over the relative humidity range of 11 to 93%. In a previous publication (1) the hygroscopic equilibrium of a sample of the D and PL variety of cottonseed was determined over the range of 31 to 93% relative humidity: Comparison of the previous and present results show that the whole seed and kernels of both varieties exhibit the same hygroscopic equilibrium behavior. A comparison of the aforementioned results with those reported by Simpson (3) on Stoneville 2B variety, and by Franco (4) on the 1A 7387 variety grown in São Paulo, Brazil, show that for intact cottonseed the hygroscopic equilibrium behavior is the same.On the basis of the curves given in Figure 1 and on the assumption that the cottonseed used was representative of cottonseed in general, it is possible to calculate the equilibrium moisture content of the whole cottonseed or any component thereof. For example, cottonseed consisting of 12.1% linters, 87.9% delintered seed, 56.0% kernels, and 31.9% lint‐free hulls, and containing 12% moisture on a whole seed basis, will yield linters, delintered seed, kernels, and lint‐free hulls having 9.4, 12.7, 10.8, and 15.4% moisture, respectively.
Lipids and fatty acids of important finfish: New data for nutrient tables
Authors: Exler J. , Kinsella J. E. , Watt B. K. 
Published: February 2007

AbstractThere is an urgent need for thorough and reliable information on the lipid content and fatty acid composition of food. Data on fish lipids (1960 to the present) have been collected and evaluated for the preparation of nutrient and food composition tables for this important commodity. Some factors affecting these data include the lack of standardization in fish nomenclature, cut of fish, season and location of catch, and variability of methods of analysis. The derivation and use of conversion factors relating wt percent methyl ester data in the literature to g fatty acid/100 g fish are described. Tabulated data are presented for total lipid and 14 fatty acids in 11 important finfish.
Use of dimethylsilyl ether derivatives in gas chromatography
Authors: Supina Walter R. , Kruppa Richard F. , Henly Robert S. 
Published: February 2007

AbstractThe results show the use of dimethylsilyl (DMS) derivatives to be valuable for: 1) decreasing retention times of samples being analyzed by gas chromatography; 2) conducting analyses at lower temperatures; 3) analyses of mixtures which cannot be separated as trimethylsilyl (TMS) derivatives; and 4) analyses of mixtures of isomers on one column as both DMS and TMS derivatives rather than using two columns with one derivative. The work reported here is only of a preliminary nature and does not include a study of the kinetics of the reaction. It is hoped that this paper will stimulate more work in this area.
Microcolumn liquid analysis of lipids with flame ionization detection
Authors: Stouffer John E. , Oakes Phillip L. 
Published: February 2007

AbstractA system for the rapid analysis of compounds which may be either too large or too sensitive to be subjected intact to gas chromatographic or other methods is described. Capillary columns of 0.5 mm and 1 mm I.D. and various lengths are packed with very fine particle size, specially prepared, silica gel and other media. A simple pumping arrangement is employed for either single solvent or gradient elution, and the solute in the effluent is detected by means of a highly sensitive flame ionization detector. The application of this system is illustrated by the separation of microgram and submicrogram amounts of triglycerides, steroids, and other neutral lipids, as well as some phospholipids.