bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of co‐deposited active layers on carrier transport and luminescent properties in organic light emitting diodes
Authors: Murata Masaya , Yamamoto Takayuki , Haishi Motoki , Ando Taro , Ohtani Naoki 
Published: October 2008

AbstractWe have investigated the influence of a co‐deposited active layer in organic light‐emitting diodes (OLEDs) on carrier transport and optical properties to improve radiative characteristics of OLEDs. The co‐deposited layer consists of two organic materials; one is a hole transport material (TPD) and the other is an electron transport/emissive material (Alq3). We evaluated current‐voltage characteristics and electroluminescence (EL) properties of various samples in which the thicknesses and compound ratios of the co‐deposited layers are different. The results indicate that the devices consisting of TPD:Alq3 co‐deposited layer sandwiched between TPD and Alq3 layers exhibit lower starting voltages for the light emission than the sample of simple TPD/Alq3 heterojunction structure. In addition, the starting voltage is independent of the thickness of TPD:Alq3 co‐deposited layer. These samples have two interfaces at both surfaces of TPD:Alq3 co‐deposited layer. Thus, we estimated the radiative recombination occurs at the interfaces. Nevertheless, we found that the radiative recombination occurs only at the interface of TPD:Alq3 co‐deposited layer and Alq3 layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Propagation dynamics of exciton spins in a high‐density semiconductor quantum dot system
Authors: Murayama A. , Furuta T. , Oshino S. , Hyomi K. , Sakuma M. , Souma I. , Dagnelund D. , Buyanova I. A. , Chen W. M. 
Published: October 2008

AbstractWe study propagation dynamics of exciton spins in a system composed of high‐density self‐assembled quantum dots (QDs) of CdSe and a diluted magnetic semiconductor (DMS) layer of ZnMnSe, where spin‐polarized excitons are generated in the DMS layer and are subsequently injected into the QDs. The degree of circular polarization, P, of excitonic photoluminescence at 5 T in the coupled QDs shows a rapid increase with increasing delay time after a linearly polarized pulsed excitation, indicating the exciton‐spin injection from the ZnMnSe to CdSe‐QDs. The P value tends to decay gradually because of the exciton‐spin relaxation in the QDs after the injection. The spin‐polarized excitons in the QD ensemble migrate simultaneously from the QDs with higher exciton energies to those with lower exciton energies, where the exciton‐spins relax inside each dot during the migration. Therefore, the observed P values in the QD emission band are affected by this feeding of the relaxed spins. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unusual features of the quaterthiophene electro‐absorption spectrum
Authors: Petelenz Piotr , Slawik Michał , Kulig Waldemar 
Published: October 2008

AbstractA previously used model describing the coupling between Frenkel and charge‐transfer (CT) excited states in a crystal with molecules arranged in close‐packed planes of herringbone pattern, is generalized to include some CT states engaging the molecules from the different planes. The corresponding Hamiltonian is parametrized for quaterthiophene and numerically diagonalized, to yield ultimately the electro‐absorption (EA) spectrum. Contrary to our recent expectations, the contribution from the newly introduced CT states is only minor. It turns out that the high‐energy EA signal of quaterthiophene is dominated by the contributions from the CT states with the electron transferred along the longer lattice period in the close‐packed plane, in contrast to the more familiar case of sexithiophene, where these states barely contribute. The reasons of this difference are pinpointed and discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radiative emission from triplet excitations in light emitting devices
Authors: Singh Jai 
Published: October 2008

AbstractUsing the recently derived time‐dependent spin‐orbit‐photon interaction operator and first order perturbation theory the rate of spontaneous radiative emission from triplet excitations in molecular solids and polymers is calculated within the two‐level approximation. The rate depends on the square of the atomic number of the constituting atoms. The calculated rates and corresponding radiative lifetimes agree very well with the known experimental results in conjugated polymers incorporated with platinum atoms. Present results are compared with the known results obtained from the traditional theory for naphthalene and anthracene and found in better agreement with experiments. The traditional theory is briefly reviewed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beyond the strong vibronic coupling approximation – sexithiophene single crystal
Authors: Stradomska Anna , Petelenz Piotr 
Published: October 2008

AbstractA new approach to vibronic coupling in molecular crystals is proposed. The underlying model describes an infinite 3‐dimensional crystal with two or four molecules in the unit cell. One Frenkel state and one vibrational mode per molecule is taken into account. The approach is rooted in the approximation of strong vibronic coupling, which is extended by taking into account the 2‐particle and 3‐particle contributions in order to cover the intermediate‐coupling region. The results of numerical calculations are presented for sexithiophene; they are discussed in the context of finite cluster models and their validity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarized photoluminescence study of whispering gallery mode polaritons in ZnO microcavity
Authors: Sun Liaoxin , Chen Zhanghai , Ren Qijun , Yu Ke , Zhou Weihang , Bai Lihui , Zhu Z. Q. , Shen Xuechu 
Published: October 2008

AbstractPolariton effect and its polarization dependence were studied in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning the excitation along the tapered arm of ZnO tetrapod with different polarizations, the photo‐exciton coupling strength were continuingly tuned and thus the resonant interaction between the WG optical modes and the excitons with different dipole orientation are clearly resolved. The experimental observations were well described by the plane wave model with excitonic polariton dispersions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Auger recombination process of biexciton in semiconducting carbon nanotubes
Authors: Watanabe Kouta , Asano Kenichi , Ogawa Tetsuo 
Published: October 2008

AbstractWe calculated the T‐matrix for the Auger recombination process of the biexciton in semiconducting carbon nanotubes (s‐CNTs) within the first Born approximation and clarified the difference between s‐CNTs and GaAs quantum wires (QWRs). The wavefunction and the binding energy of the biexciton, EXX, are given by the dynamics controlled truncation (DCT) scheme. We find that the Auger recombination rate is ħ/τ ∼ 0.1EXX. This means that the Auger recombination process doesn't prevent the biexciton formation. In addition, the Auger recombination rate is much larger than that of the QWR. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering spectra of CdS nanocrystals fabricated by a reverse micelle method
Authors: Yamamoto Aishi , Endo Hiroki , Matsuura Norihiro , Ishizumi Atsushi , Kanemitsu Yoshihiko 
Published: October 2008

AbstractRaman scattering (RS) spectra of CdS nanocrystals (NCs) fabricated by a reverse micelle method were studied and were analysed using a phonon confinement model. One broad and red‐shifted RS peak due to the LO phonon confined in CdS NCs was observed. The RS spectra were calculated using a phonon confinement model with the NC sizes estimated from the optical absorption spectra. The calculated RS spectra as suming that the NCs have the wurtzite structure reproduce the experimental spectra better than those assuming zincblende structure, which is consistent with the result of transmission electron microscope (TEM) observations. Our finding indicates that the crystal structure of the nanocrystal can be determined by the analyses of Raman scattering spectral shape. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quasi‐equilibrium emission of excited semiconductors
Authors: Richter F. , Manzke G. , Henneberger K. 
Published: October 2008

AbstractAs a first detailed study on the basis of a recently found basic law for the non‐equilibrium energy flow in bounded media, we examine the absorption spectra of an excited semiconductor slab and present detailed calculations for its emission spectra in quasi‐equilibrium. The density of excited carriers is varied from the excitonic regime up to densities where gain appears.Different slab lengths are regarded, and the dependence on the angle of incidence is studied. The absorption and emission spectra follow the Fabry‐Perot resonances in the slab. Depending on its length, excitation, and the position of the resonances, the formation of sharp and strong emission lines is observed, and degeneracy effects become apparent. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Kirchhoff index and the matching number
Authors: Zhou Bo , Trinajstić Nenad 
Published: October 2008

AbstractThe Kirchhoff index of a connected (molecular) graph is the sum of the resistance‐distances between all unordered pairs of vertices and may also be expressed by its Laplacian eigenvalues. We determine the minimum Kirchhoff index of connected (molecular) graphs in terms of the number of vertices and matching number and characterize the unique extremal graph. The results on the Kirchhoff index are compared with the corresponding results on the Wiener index. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Computer‐assisted implant surgery; a flapless surgical/immediate loaded approach with 1 year follow‐up
Authors: Nikzad Sakineh , Azari Abbas 
Published: October 2008

AbstractBackgroundIt has been suggested that for success with immediate loaded dental implants it is necessary that, prior to their placement, bone quantity and quality as well as the biomechanical environment in which the implants are to function be evaluated. However, conventional techniques currently used for immediate implant placement lack sufficient precision and are usually accomplished by opening flap procedures. The purpose of this paper is to report the benefit of sophisticated pre‐operative diagnostic implant planning and a flapless surgical approach with immediate loading.MethodsThe report describes the use of computed tomography (CT) for three‐dimensional (3D) evaluations of bone implant sites, an interactive software program for 3D planning and the fabrication of stereolithographic models as custom surgical templates. The degree of patient satisfaction was evaluated by periodic recall and by adopting a specially designed analogue scale in each visit.ResultsThe mean amount of bone loss around the implants was 0.5 ± 0.1 mm and the satisfactoriness scale was rated high (i.e. 81), at the end of 1 year.ConclusionThe use of stereolithographic appliances in accordance with flapless surgery makes immediate placement of the implants more predictable. Copyright © 2008 John Wiley & Sons, Ltd.
Urban environmental performance in China: a sustainability divide?
Authors: Liu Lee 
Published: October 2008

AbstractThis paper explores a sustainability divide in urban environmental protection in China with its 72 Model Cities, 113 key cities, and 43 most polluted cities. It investigates factors that help understand such a divide, the applicability of the environmental Kuznets curve (EKC), and policies for sustainable urban development. Geographic information systems (GIS) and statistical analyses used data derived from documents, statistical records, publications, on‐site inspections and field research. The key cities were divided into seven groups based on eight environmental indicators. The research found a sustainability gap between eastern and western cities, or between Model Cities and other key cities. Oddly, environmental spending was not found to be an explanation. The paper argues that sustainability studies needs to move beyond the EKC to consider the role of nature. Chinese policy makers should not use the Model Cities to support the ‘grow first and clean up later’ approach. Instead they should promote sustainability in all parts of China. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Challenges in operating sustainability initiatives in Northwest Mexico
Authors: Velázquez Luis , Munguía Nora , Zavala Andrea , Navarrete Maria de los Ángeles 
Published: October 2008

AbstractThis paper is aimed at describing the evolutive strategy that the University of Sonora is following to promote regional sustainable development initiatives in Northwest Mexico as well as debating the challenges in implementing it effectively. The institutional partnership and outreach efforts with local industries, community groups, governmental agencies, educational institutions and non‐governmental organizations comprise the provision of technical assistance, advising services, performance of demonstration projects and capacity building.There are both significant challenges and opportunities for industry facing the dilemma of compliance with environmental and occupational pressures. These challenges have serious practical and theoretical implications not only for conducting sustainability research studies but also for implementing cleaner production and pollution prevention interventions. Slowly but surely, regional sustainability leaders have increased their capacity to better respond to awkward sustainability situations; capacity building has been a central task in ensuring the use of the resources and in ensuring an adequate performance.As outlined in this paper, adequate conditions for the successful implementation of regional sustainability initiatives are not present. Low levels of awareness, lack of external drives, data uncertainty and lack of capacity have emerged as main barriers preventing success. Additional challenges to sustainability progress include lack of time, lack of interest, lack of funding and lack of training. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Applying permutation tests with adjustment for covariates and attrition weights to randomized trials of health‐services interventions
Authors: Tang Lingqi , Duan Naihua , Klap Ruth , Asarnow Joan Rosenbaum , Belin Thomas R. 
Published: October 2008

AbstractUsing a health‐services study as an illustrative example of longitudinal randomized field research with the potential for participants to be lost to follow‐up, we apply a permutation test where the treatment indicator variable is randomly permuted in the context of regression models with covariates and attrition weighting. The test is applied to a multi‐site randomized intervention trial of a quality‐improvement program for adolescent depression treatment in primary‐care settings, in which regression models were used to assess intervention effects with weights used to adjust for attrition bias. The foundation and motivation for this approach to the analysis are considered with attention to the demands associated with implementing such a strategy. The results from the permutation tests were qualitatively similar to the results obtained from conventional parametric models, and in fact suggested that the significance level from the conventionalt‐test was understated in this application. Copyright © 2008 John Wiley & Sons, Ltd.
Maximum likelihood, multiple imputation and regression calibration for measurement error adjustment
Authors: Messer Karen , Natarajan Loki 
Published: October 2008

AbstractIn epidemiologic studies of exposure–disease association, often only a surrogate measure of exposure is available for the majority of the sample. A validation sub‐study may be conducted to estimate the relation between the surrogate measure and true exposure levels. In this article, we discuss three methods of estimation for such a main study/validation study design: (i) maximum likelihood (ML), (ii) multiple imputation (MI) and (iii) regression calibration (RC). For logistic regression, we show how each method depends on a different numerical approximation to the likelihood, and we adapt standard software to compute both MI and ML estimates. We use simulation to compare the performance of the estimators for both realistic and extreme settings, and for both internal and external validation designs. Our results indicate that with large measurement error or large enough sample sizes, ML performs as well as or better than MI and RC. However, for smaller measurement error and small sample sizes, either ML or RC may have the advantage. Interestingly, in most cases the relative advantage of RC versus ML was determined by the relative variance rather than the bias of the estimators. Software code for all three methods in SAS is provided. Copyright © 2008 John Wiley & Sons, Ltd.
Guidelines for effective eridging in global software engineering
Authors: Milewski Allen E. , Tremaine Marilyn , Köbler Felix , Egan Richard , Zhang Suling , O'Sullivan Patrick 
Published: October 2008

AbstractGlobally distributed software engineering involves one or more of geographic, temporal or cultural distances, which empirical studies find have deleterious effects on the efficiency of the software engineering process. There have been some successful examples where one ‘bridge’ location has facilitated collaboration and coordination across the other locations. Managers might want to use this bridging as a tactic for future projects, even when future collaborations may be composed of very different participants and in different locations and contexts than current successfully bridged teams. However, group behaviour is complicated and establishing an effective bridge is neither a simple nor a straightforward step. We propose a set of guidelines, based on empirical findings, to help managers understand what to expect from the bridging tactic. These include cultural, organizational, individual and temporal factors as well as insights into the costs and benefits of bridging. Copyright © 2008 John Wiley & Sons, Ltd.
Association of lifetime cadmium intake or drinking Jinzu River water with the occurrence of renal tubular dysfunction
Authors: Kobayashi Etsuko , Suwazono Yasushi , Dochi Mirei , Honda Ryumon , Kido Teruhiko 
Published: October 2008

AbstractThis study was performed to clarify whether lifetime cadmium (Cd) intake (LCd) calculated from consumption of Cd‐polluted rice and other foods, or drinking and/or cooking with Jinzu River water is associated with the occurrence of renal tubular dysfunction and to estimate the threshold level of LCd using a benchmark dose procedure. From participants in the 1967 and 1968 health examinations, the 2607 subjects (1430 men and 1177 women) who were aged 50 years or more, and who had either resided in the current hamlet since birth or moved there from a nonpolluted area and resided for a total of 30 years or longer were chosen as the target population. Based on a multiple logistic regression analysis performed for abnormal urinary findings (proteinuria, glucosuria, or proteinuria with glucosuria) using LCd as the explanatory variable with or without consideration of use of the river water for drinking and/or cooking, it was inferred that both factors of LCd and use of the river water influenced the occurrence of renal tubular dysfunction, with LCd appearing to exert a greater impact compared to drinking/cooking with the river water. Moreover, the threshold values of LCd for proteinuria with glucosuria were estimated to be 2.91 g in men and 1.79 g in women, without adjustment for use of the river water. After adjustment for its use, the values of proteinuria were calculated to be 0.93 g in women. When assuming user/nonuser status of the river water, the threshold level was calculated as 0.75/0.93 g in women. The difference of 0.18 g was interpreted as representing the influence of drinking/cooking with the river water. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Homonymous role in role‐based discretionary access control
Authors: Chu Xiaowen , Ouyang Kai , Chen Hsiao‐Hwa , Liu Jiangchuan , Jiang Yixin 
Published: October 2008

AbstractThe access control model is a core aspect of trusted information systems. Based on the role based access control (RBAC) model, we put forward the concept of thehomonymous role, which extends the role control categories in RBAC, balances the control granularity and the storage space requirements, and executes the fine‐grained access control. Instead of the traditional global access control policies (GACP), we propose thehomonymous control domain(HCD) mechanism to enable the coexistence of multiple types of access control policies in a single system, thereby improving the control granularity and flexibility. The HCD mechanism facilitates the discretionary supporting of independent access control policies for its homonymous user. The HCD mechanism and the traditional access control mechanism can be linked to construct a two‐layer access control policy mechanism for a system. Notably, we also consider the temporal characteristic in HCD, which is a critical feature of modern access control models. Furthermore, we analyze the conflicts between the HCD and GACP mechanisms. Finally, we design and implement our HCD on FreeBSD to demonstrate the advantages of the two‐layer access control mechanism. Copyright © 2008 John Wiley & Sons, Ltd.
Eulerian and Lagrangian formulations of steady rotating annuli
Authors: Shum Wai Sun , Lin Zhang 
Published: October 2008

AbstractIt is interesting to ask if there are any fundamental differences between Eulerian and Lagrangian formulations in structural dynamics problems. Steady rotating annuli formulated in both Eulerian and Lagrangian coordinates are exemplified for the present study. Nonlinear strain‐displacement relationships for radial vibration only without circumferential motion in polar coordinates are derived. Linear and nonlinear strain‐displacement relationships are implemented to form the governing equations and are compared to check for the validity of small strain analysis. By including the Poisson's effect, the resulting governing equations are nonlinear equations with material density redistribution and plate thickness variation. Analytical solutions of the linearized versions of nonlinear Eulerian and Lagrangian governing equations by keeping material density and plate thickness constant are offered. Fundamental issues in existence and uniqueness of analytical solutions are discussed between linear Eulerian and linear Lagrangian formulations. Furthermore, the fundamental difference of imposing free edge boundary conditions in Eulerian and Lagrangian coordinates is emphasized. Results show that there are in general insignificant differences between Eulerian and Lagrangian descriptions for circular plate problems, although the approaches to solve the problems in the two formulations are quite different.
A Brazilian galactosialidosis patient given renal transplantation: A case report
Authors: Kiss A. , Zen P. R. G. , Bittencourt V. , Paskulin G. A. , Giugliani R. , d'Azzo A. , Schwartz I. V. 
Published: October 2008

SummaryWe report a Brazilian girl who was diagnosed as having galactosialidosis (deficiency of protective protein/cathepsin A; PPCA deficiency; GS) at the age of 2 years 6 months during an extensive investigation for renal failure. She was found to have low levels of both β‐galactosidase and α‐neuraminidase in fibroblasts and to be a carrier of two novel mutations in thePPGBgene (p.G57V and p.R396W). She received a renal allograft at the age of 3 years 4 months. Transplantation was successful and graft function remains excellent after 6 years. However, the patient shows signs of progression of her primary disease. To our knowledge, she is the first GS patient to be given renal transplantation worldwide. We propose that renal transplantation should be considered as a therapeutic option for the treatment of severe renal complications of GS.