bluuebunny/crossref_metadata_2025_split huggingface dataset:
Conjugated and partially conjugated 2,5‐diphenylthiophene‐containing light‐emitting copolymers in polymeric light‐emitting diode (PLED) device fabrications
Authors: Wu Sheng‐Han , Chen Jar‐Hung , Shen Chi‐Hsien , Hsu Chia‐Chen , Tsiang Raymond Chien‐Chao 
Published: October 2004

AbstractTo study the effect of nonconjugation on polymeric and photophysical properties of thiophene‐containing polymers, new light‐emitting copolymers comprising either alternate 2,5‐diphenylthiophene and vinylene or alternate 2,5‐diphenylthiophene and aliphatic ether segments were synthesized. Both copolymers contained 2,5‐diphenylthiophene as the major chromophore and emitted a sky bluish fluorescence in dilute solution (10−2 mg/mL). With a rigid and planarity structure and the concomitant crystallinity, the former copolymer (fully conjugated) possessed a higher quantum efficiency, a higher glass‐transition temperature, and a better thermal stability. In contrast, the latter copolymer (conjugated–nonconjugated) had better solubility and provided enhanced photophysical properties for the fabricated polymeric light‐emitting diode (PLED) device: at 15 V, the maximum current and brightness were 110 mA/cm2 and 4289 cd/m2, respectively, and the electroluminescence efficiency remained constant at approximately 4.9 cd/A in a voltage range of 8 to 14 V. The existence of intramolecular/intermolecular aggregates in the latter copolymer was corroborated from the the UV–vis and photoluminescence spectra of its solutions. With an increase in solution concentration, the shape and λmax of the photoluminescence spectrum were redshifted. In a solution with a concentration as high as 10 mg/mL, the redshift was so drastic that the photoluminescence spectrum was nearly identical to that of a solid‐film. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 6061–6070, 2004
Jet Initiation Tests
Authors: Held Manfred 
Published: October 2004

AbstractTwo tests with the same test setup and with the same nominal type of acceptor charge will be described which give in both cases an initiation after a build‐up distance of around 45 mm. But in one case a retonation started, and in the other case a second initiation centre was observed after an additional delay time of 6.4 μs. In the already perforated charge segment the detonation wave was running around an internal core and was interacting in a Dautriche event on the observed front side. Very similar results have already been observed in a very early study of jet initiation tests. Both test results are described in detail, their analyses are presented and compared to the results of the observations, some decades ago.
Management of five stored‐product insects in wheat with pirimiphos‐methyl and pirimiphos‐methyl plus synergized pyrethrins
Authors: Huang Fangneng , Subramanyam Bhadriraju 
Published: October 2004

AbstractHard red winter wheat was treated with pirimiphos‐methyl at 4, 6 and 8 mg kg−1, synergized pyrethrins at 0.38, 0.75, 1.13 and 1.5 mg kg−1, and combinations of the two insecticides, to conduct laboratory bioassays against four beetle pests of stored grain, red flour beetle Tribolium castaneum (Herbst), rusty grain beetle Cryptolestes ferrugineus (Stephens), lesser grain borer Rhyzopertha dominica (F), and rice weevil Sitophilus oryzae (L), and one moth pest, Indianmeal moth Plodia interpunctella (Hübner). Beetle adults and P interpunctella larvae survived well on control wheat, producing a large number of progeny (65–1037 insects per container). Kernel damage in control wheat among the insect species ranged from 9 to 99%. On pirimiphos‐methyl‐treated wheat, mortality of R dominica adults was ≥72%, but that of the other beetle species and P interpunctella larvae was 100%. Progeny were not produced on pirimiphos‐methyl‐treated wheat, and the kernel damage was negligible (≤1%). Synergized pyrethrins were ineffective against the five insect pests. Pirimiphos‐methyl combined with synergized pyrethrins was not superior to pirimiphos‐methyl alone against the five insect pests. Pirimiphos‐methyl is not registered in the USA for use on wheat, but our results suggest that it could be a viable grain protectant at rates of 4–8 mg kg−1. Copyright © 2004 Society of Chemical Industry
Herbicidal indolizine‐5,8‐diones: photosystem I redox mediators
Authors: Smith Stephen C , Clarke Eric D , Ridley Stuart M , Bartlett David , Greenhow Daren T , Glithro Harry , Klong Agnes Y , Mitchell Glynn , Mullier Graham W 
Published: October 2004

Abstract6,7‐Disubstituted indolizine‐5,8‐diones showed activity as herbicides, giving rapid desiccation symptomology in whole‐plant tests and bleaching in leaf‐disc assays. In isolated chloroplasts, such compounds initiated rapid uptake of oxygen in Photosystem I. A redox mediator mode of action was further supported by electrochemical studies. Several compounds described had low photostability, high volatility, hydrolytic instability or reactivity with glutathione. The detrimental effects that these factors may have had on expression of herbicidal activity are discussed. Copyright © 2004 Society of Chemical Industry
Carrier leakage suppression utilising short‐period superlattices in 980 nm InGaAs/GaAs quantum well lasers
Authors: Lock D. , Sweeney S. J. , Adams A. R. , Deubner S. , Klopf F. , Reithmaier J. P. , Forchel A. 
Published: October 2004

AbstractShort‐period Super Lattices (SSLs) have been proposed as a method of reducing carrier leakage in semiconductor lasers. SSLs increase the carrier confinement by increasing the effective barrier height due to the carriers being “reflected” from the SSL. Thermionically driven leakage of electrons from the quantum wells has been suggested as an important non‐radiative current path in (Al)GaAs based devices which is exacerbated at high temperatures. Due to the fact that the application of high pressure causes a reduction in the zone centre Γ–X minima splitting, pressure can be used to investigate the extent to which such leakage increase the threshold current. In this study, we compare devices with and without SSL layers and find direct evidence for leakage suppression in devices containing SSLs up to a temperature of 60 °C. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of pressure on deep levels in semiconductors: The MFe center in InP
Authors: Samara G. A. , Barnes C. E. 
Published: October 2004

AbstractThis work investigated the effects of hydrostatic pressure on the properties and bistability of the scientifically challenging and technologically important deep MFe center in iron (Fe)‐doped, n‐type indium phosphide (InP). When occupied by electrons, the center can be reversibly placed in either of two configurations, termed A and B, by the proper choice of electric biasing conditions and temperature. Pressure has a very large influence on the balance between these two configurations, favoring A over B. Above 8 kbar essentially only the A configuration is observed. This result, along with detailed studies of the effects of pressure on the energetics of the two configurations and on the kinetics of the B → A transformation, provide important new insights about the nature of the two configurations and their associated deep levels. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of high pressure on the photoluminescence transitions of excitons in α‐PTCDA (perylene tetracarboxylic dianhydride) crystals
Authors: Tallman R. E. , Weinstein B. A. , DeSilva A. , Wagner H. P. 
Published: October 2004

AbstractWe report investigations of the photoluminescence (PL) spectrum of α‐PTCDA single crystals at 11 K and 300 K as a function of applied pressures to 54 kbar carried out using a diamond‐anvil cell with annealed methanol‐ethanol medium. The effects of pressure are observed on several excitonic PL features principally associated with: an excimer transition for the 300 K spectra, or an indirect Frenkel exciton and charge transfer exciton transitions (between stacked molecules in different unit cells) for the 11 K spectra. Under applied pressure, all of these features redshift at rates that are in general accord with the π – π* broadening caused by increasing overlap between PTCDA molecules, but with variations in pressure dependence, especially in the quadratic shifts, that derive from the specific character and Stokes‐shift mechanisms of the exciton transitions. The observed pressure behavior conforms to a recent model of the exciton transitions in α‐PTCDA based on a theoretical analysis of 1 atm time‐resolved PL experiments. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electronic structure of Sm and Eu chalcogenides
Authors: Svane A. , Santi G. , Szotek Z. , Temmerman W. M. , Strange P. , Horne M. , Vaitheeswaran G. , Kanchana V. , Petit L. , Winter H. 
Published: October 2004

AbstractThe ground state configuration of the monochalcogenides of Sm and Eu is determined from total energy calculations using the self‐interaction corrected local‐spin‐density approximation. The Sm chalcogenides, with the exception of SmO, are characterized by divalent f6 Sm ions, while all the Eu chalcogenides have divalent f7 Eu ions in the ground state. With pressure, the Eu and Sm chalcogenides exhibit isostructural transitions into an intermediate valent state, which in the total energy calculations is represented by localized f5 configurations on the Sm ions (f6 on Eu ions) together with a partly occupied f‐band at the Fermi level. The energy of the fundamental f → d transition, which determines the value of the semiconducting gap, is determined by total energy calculations of the charged rare earth ion (Eu+ or Sm+) in a supercell approach with one f‐electron removed. The pressure coefficients are in excellent agreement with experiment, and the occurrence of isostructural transitions is intimately related to the closure of the band gap. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Squeezing carbon nanotubes
Authors: Venkateswaran Uma D. 
Published: October 2004

AbstractIn this paper we briefly review the high pressure Raman studies on single and double walled carbon nanotubes focussing on the perssure dependence of the low frequency radial breathing vibrational modes. Previous work on single walled carbon nanotube bundles have shown that the normalized pressure‐induced frequency shift, Φ = (1/ωR) (dωR/dP) ∼ D2, where ωR is the radial mode frequency and D is the nanotube diameter. We show here that the R‐modes due to the inner tubes in double walled carbon nanotubes, have a very small, diameter independent value for Φ, as predicted for the case of isolated tubes. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High pressure phase transition and variation of elastic constants of diluted magnetic semiconductors
Authors: Varshney Dinesh , Sharma P. , Kaurav N. , Shah S. , Singh R. K. 
Published: October 2004

AbstractA theoretical study of the high‐pressure phase transition and elastic behavior in diluted magnetic semiconductors Zn0.83Mn0.17Se, using a three‐body interaction (TBI) potential caused by the electron‐shell deformation of the overlapping ions is carried out. The estimated values of phase transition pressure and the vast volume discontinuity in pressure‐volume (PV) phase diagram indicate the structural phase transition from zincblende (B3) to rock salt (B1). The variation of second‐order elastic constants with pressure resembles that observed in some binary semiconductors. The inconsistency in the deduced value of pressure derivative of second order elastic constant with the available data is attributed to the fact that we derive expressions neglecting thermal effects and assuming the overlap repulsion significant only up to nearest neighbors. The vdW interaction is effective in obtaining the thermodynamical parameters such as Debye temperature, Gruneisen parameter, thermal expansion coefficient, compressibility as well phase stability in diluted magnetic semiconductors. It is revealed that TBI model has a promise to predict the phase transition pressure and the pressure variation of elastic constants of other semiconductors as well. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural properties of some semiconducting LnAs compounds at high pressure
Authors: Pagare Gitanjali , Srivastava Vipul , Sanyal Sankar P. , Singh R. K. 
Published: October 2004

AbstractThe structural properties of four semiconducting LnAs compounds (REY:RE = Ce, Pr, Nd and Sm; Y = As) at high pressure have been investigated theoretically using an inter‐ionic potential method. The strong mixing of the f‐band with the p‐orbitals of the nearest neighbour As, that substantially screens the effective Coulomb interactions, has been considered as a potential parameter. Three REY compounds (except CeAs) have been found to undergo a NaCl to body centered tetragonal phase transition at high pressure and agree well with their corresponding experimental results. The simulated ion‐ion (RE‐RE and RE‐As) distances follow as systematic trends of variation as observed from the high‐pressure measurements. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure induced wavelength dependence of catastrophic optical damage in 980 nm semiconductor diode lasers
Authors: Lock D. , Sweeney S. J. , Adams A. R. 
Published: October 2004

AbstractCatastrophic Optical Damage (COD) occurs when the facet of high power semiconductor lasers melt due to extreme self‐absorption. COD tends to occur in short wavelength lasers but seems to be less of a problem in long wavelength devices. In this paper, we use hydrostatic pressure as a means of changing the wavelength in order to investigate the dependence of COD on emission wavelength. We find that the recorded output power threshold at the onset of COD decreases with increasing pressure (decreasing wavelength). Our measurements further reveal that this threshold is closely correlated with the increase in optical confinement factor with pressure which suggests that the wavelength dependence may largely be attributed to the change in mode size with operating wavelength. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Hydrostatic pressure effects on the structural and electronic properties of carbon nanotubes
Authors: Capaz Rodrigo B. , Spataru Catalin D. , Tangney Paul , Cohen Marvin L. , Louie Steven G. 
Published: October 2004

AbstractWe study the structural and electronic properties of isolated single‐wall carbon nanotubes (SWNTs) under hydrostatic pressure using a combination of theoretical techniques: Continuum elasticity models, classical molecular dynamics simulations, tight‐binding electronic structure methods, and first‐principles total energy calculations within the density‐functional and pseudopotential frameworks. For pressures below a certain critical pressure Pc, the SWNTs' structure remains cylindrical and the Kohn–Sham energy gaps of semiconducting SWNTs have either positive or negative pressure coefficients depending on the value of (n, m), with a distinct “family” (of the same n–m) behavior. The diameter and chirality dependence of the pressure coefficients can be described by a simple analytical expression. At Pc, molecular‐dynamics simulations predict that isolated SWNTs undergo a pressure‐induced symmetry‐breaking transformation from a cylindrical shape to a collapsed geometry. This transition is described by a simple elastic model as arising from the competition between the bond‐bending and PV terms in the enthalpy. The good agreement between calculated and experimental values of Pc provides a strong support to the “collapse” interpretation of the experimental transitions in bundles. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photophysics of organic emissive semiconductors under hydrostatic pressure
Authors: Guha S. , Chandrasekhar M. 
Published: October 2004

AbstractThe impact of hydrostatic pressure on conjugated organic semiconductors has been studied using optical spectroscopic techniques. This work focuses on three blue emitters with distinct backbone conformations: planar methylated ladder‐type poly para phenylene, semi‐planar polyfluorene (PF), and nonplanar para hexaphenyl. The effect of pressure on the backbone emission and defect related emission allows an understanding of the localized, delocalized electronic states and energy transfer mechanisms of the singlet excitons into defect states. The Raman spectrum of the organic emitters under pressure demonstrates changes in the backbone conformation and mesomorphic phases. The Raman peaks in PF exhibit asymmetric Fano‐type line shapes beyond 40 kbar, where the defect emission is enhanced. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Moving target detection from infrared images using genetic algorithms
Authors: Kikuchi Minoru , Kimura Hajime , Kobayashi Shigenobu 
Published: October 2004

AbstractThis paper presents the configuration of an image processing system for efficiently detecting a moving target from infrared images of a scene with a complicated background such as an urban area, and improving the target detection accuracy by optimizing the weights of the feature vectors by genetic algorithms (GA). The proposed system applies edge‐enhancing binary processing with a background suppressing function and motion vector processing with a moving body detection function in parallel to the input infrared images. It performs target decision or detection processing by using eight features obtained by the above two kinds of processing. In order to improve the identification capability of target decision or detection, optimization of the weights of the feature vectors is performed by means of a GA. In addition, an effort is made to improve target detection accuracy by using gate processing to limit the processed area. The effectiveness of the proposed system is verified by applying it to the detection of an airplane against the background of an urban area. The proposed system attempts to shorten the processing time by parallel processing by a simplified configuration that combines the basic processes, assuming its application to guided mechanism with space and processing time constraints, and may be applied to traffic monitoring, harbor monitoring, field search monitoring systems, and the like. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 76–86, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10168
Method for detecting a learner's stalled situation by using the variance of operational time intervals
Authors: Nakamura Yoshihiro , Akamatsu Norio , Kuwabara Tsuneo , Tamaki Motonori 
Published: October 2004

AbstractAutomatically detecting a learner's stalled situation or deadlock in an educational support system using computers is very useful. This paper proposes a method for detecting such a deadlock on the basis of the record of a learner's operations and evaluates it by tests on human subjects. Specifically, it uses the moving variance of the operational time intervals to detect a deadlock. As a result, in about 80% of the practice problems with self‐declarations of a deadlock by the subjects, the deadlock could be detected at a point in time prior to the self‐declarations. In addition, deadlocks were detected by the proposed method in three cases in which states close to a deadlock had been determined from questions after the completion of the practice problems, even though there were no self‐declarations. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 63–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10256
Lombard speech recognition based on voiced sound detection and application to the fabric inspection system in factories
Authors: Kanno Sukeyasu , Funada Testuo 
Published: October 2004

AbstractIn a very noisy environment such as a factory, the performance of speech recognition drops due to the presence of noise and the Lombard effect. Given this, the present authors consider a method to recognize noisy Lombard speech as based on the effective detection of voiced sound period under noisy conditions in a factory. Based on recognition experiments using a 120‐word vocabulary spoken by three men, the authors showed that recognition performance for noisy Lombard speech was high when the WGD measure used speech under noisy conditions as a reference pattern. Then the authors confirmed, based on the proposals in this paper, the effects of weighting distance in the voiced sound period and the effectiveness of using word periods based on voiced sound. In addition, the authors developed an inspection system using speaker‐dependent speech recognition based on the results of these evaluations. The results of operational experiments to input the names of fabric defects (a 61‐word vocabulary) by voice in an inspection factory (noise level: 75 to 90 dBA) yielded a recognition rate of 93.1%, clearly improving operating efficiency. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 10–23, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10369
Inter‐temporal economies of scope, organizational modularity, and the dynamics of diversification
Authors: Helfat Constance E. , Eisenhardt Kathleen M. 
Published: October 2004

AbstractThe question of whether corporations add value beyond that created by individual businesses has engendered much debate in recent years. Some of this debate has focused on the pros and cons of related vs. unrelated diversification. A standard explanation of the benefits of related diversification has to do with the ability to obtain intra‐temporal economies of scope from contemporaneous sharing of resources by related businesses within the firm. In contrast, this paper deals with inter‐temporal economies of scope that firms achieve by redeploying resources and capabilities between related businesses over time, as firms exit some markets while entering others. The transfer of resources due to market exit distinguishes our treatment of inter‐temporal economies of scope from standard intra‐temporal economies of scope. In addition, these inter‐temporal economies can benefit from a decentralized and modular organizational structure. This ability to obtain inter‐temporal economies of scope via organizational modularity and recombination suggests that corporations do not necessarily need a high degree of coordination between business units in order to benefit from a strategy of related diversification. Copyright © 2004 John Wiley & Sons, Ltd.
The Psychiatry of Quislingism: Norwegian Psychiatric Research on the Collaborators of World War II
Authors: Giæver Øyvind 
Published: October 2004

ArgumentThe paper focuses on a research project launched by Norwegian psychiatrists immediately following World War II. The project sought to investigate the roots of quislingism (collaboration with the Nazis) through psychiatric research on the collaborators. Considered with hindsight, however, the methodology of the project seems puzzlingly shallow. The paper discusses whether this was due to a general lack of adequate methodology in the contemporaneous sciences, or whether the explanation must be sought in the project's social and historical context. Ultimately, I conclude that considerable weight must be placed on the latter explanation, and that the general political ostracism of the collaborators in the postwar years played a major role in the psychiatrists' attitude.