bluuebunny/crossref_metadata_2025_split huggingface dataset:
The optical spectra of confined polygermanes: from bulk film down to nanosize layers
Authors: Ostapenko Nina , Kozlova Nata , Nanjo Masato , Mochida Kunio , Suto Shozo 
Published: October 2008

AbstractThe monitoring of poly(di‐n‐hexylgermane) (PDHG) optical spectra in a variety of structures ranging from a polymer film to nanosize polymer filled porous media was performed by optical spectroscopy in the temperature range from 5 to 250 K. The PDHG nanocomposites were fabricated by insertion of PDHG polymers into SBA‐15 mesoporous silica and SiO2 porous films. Temperature dependence of the PDHG film fluorescence spectra shows that the polymer generally has disordered conformation while the random ordered segments behave as defects. The spectra of the composites correspond to the polymer chains with even less ordered segments and the aggregates of such chains. This is confirmed by the absence of the thermochromic transition in the composites contrary to the film. The difference between the optical spectra of the film and the composites is due to a decrease of both the intermolecular and exciton‐phonon interactions in the composites. It was shown that the polymer chains in the SiO2 pores are more ordered. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Excitons in perylene tetracarboxdiimide crystals for optoelectronics
Authors: Provencher Françoise , Laprade Jean‐Frédéric , Côté Michel , Silva Carlos 
Published: October 2008

AbstractIn this contribution, we present steady‐state and timeresolved photoluminescence measurements, as well as absorbance measurements, on dilute solutions and on solution‐grown crystals of a perylene tetracarboxdiimide derivative (EPPTC). We also present density functional theory (DFT) calculations of their electronic structure. These molecules self‐assemble into highly anisotropic needle‐shaped crystals with monoclinic structure, as revealed by X‐ray diffraction techniques and polarized optical microscopy.We find experimentally that the Huang‐Rhys factor for this molecule is 0.565, which is in good agreement with that extracted from ab initio calculations (0.678). We demonstrate that in a film, the nature of photoexcitations is a vibrationally dressed Frenkel exciton and that these recombine radiatively with a distribution of excited‐state constants centered at ∼ 1 ns–1. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐resolved absorption and luminescence following electron‐hole pair creation in ZnO
Authors: Wall R. Andrew , Lipke Kyle C. , Ucer K. B. , Williams R. T. , Millers D. , Smits K. , Grigorjeva L. 
Published: October 2008

AbstractWe report transient absorption induced by electron‐hole excitation in undoped ZnO. A laser pump/continuum probe method covers 2–300 ps, and an electron pulse with lamp transmission covers 8–300 ns. The broad absorption spectrum increases monotonically with wavelength from 900 to 1600 nm. Following a reasonable hypothesis that the free‐carrier‐like induced infrared absorption is proportional to the total number of free carriers, excitons, and shallow‐trapped carriers in the sample, these data allow setting an upper limit on the quantum efficiency of a specified lifetime component of luminescence. For the undoped commercial ZnO studied in this report, the quantum efficiency of room temperature excitonic luminescence is less than 5%. This means that there is significant room for improvement in applications aiming to use room‐temperature excitonic blue luminescence of ZnO for fast scintillators and light sources. Direct observation that a large majority of excitations are tied up for more than 100 nanoseconds in shallow traps confirms the premise for studies undertaken at Oak Ridge National Laboratory to improve the excitonic luminescence yield and decay rate of ZnO by donor doping. The preliminary results presented here on undoped ZnO suggest that induced absorption measurements should be a useful diagnostic of quantum efficiency while studying such dopant effects. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multichanneled relaxation of halogen‐bridged diplatinum chain complexes photoexcited
Authors: Yamamoto Shoji , Ohara Jun 
Published: October 2008

AbstractEmploying a time‐dependent Hartree‐Fock method, we simulate photoexcitation and the following nonlinear lattice relaxation of quasi‐one‐dimensional binuclear platinum complexes with bridging halogens. High‐energy excitations above the electron‐hole continuum tend to relax into polarons, while excitons pumped within the optical gap can be stabilized into solitons.Both neutral and charged solitons appear as stable photoproducts, which is not the case with conventional platinum‐halide chains. When a pair of kink and antikink is born out of a self‐trapped exciton and recombine to disappear, excess spin and charge densities alternate and oscillate on them. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical spin injection into InGaAs quantum dots: single dot devices and time‐resolved studies
Authors: Hetterich M. , Löffler W. , Aßhoff P. , Flügge H. , Müller J. , Westenfelder B. , Hu D. Z. , Schaadt D. M. , Kalt H. 
Published: October 2008

AbstractIn the context of a potential future quantum information processing we investigate the concurrent initialization of electronic spin states in InGaAs quantum dots (QDs) via electrical injection from ZnMn(S)Se spin aligners. Single dots can be read out optically through metallic apertures on top of our spin‐injection light‐emitting diodes (spin‐LEDs). A reproducible spin polarization degree close to 100% is observed for a subset of the QD ensemble. However, the average polarization degree is lower and drops with increasing QD emission wavelength. Our measurements suggest that spin relaxation processes outside the QDs, related to the energetic position of the electron quasi‐Fermi level, as well as defect‐related spin scattering at the III–V/II–VI interface should be responsible for this effect, leading us to an improved device design. Finally, we present first time‐resolved electroluminescence measurements of the polarization dynamics using nanosecond‐pulsed electrical excitation. The latter should enable us to gain a more detailed understanding of the spin relaxation processes in our devices. They are also the first step towards future time‐resolved spin manipulation experiments. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of homogeneous and inhomogeneous broadenings of quantum‐well excitons by 2DFTS: An experiment‐theory comparison
Authors: Kuznetsova Irina , Thomas Peter , Meier Torsten , Zhang Tianhao , Cundiff Steven T. 
Published: October 2008

AbstractThe recently developed two‐dimensional Fourier‐Transform‐Spectroscopy (2DFTS) in the optical regime has been established as an elegant experiment, which has manifold of applications in the investigation of semiconductor nanostructures. Here we focus on the real and imaginary part 2DFT spectra. As predicted recently, using rephasing and non‐rephasing modes, we are able to determine the homogeneous and inhomogeneous broadenings of coupled excitonic resonances even for weak disorder where photon‐echo data are not useful. Computed real and imaginary parts of the 2DFTS for rephasing and non‐rephasing modes are compared with experimental data of a GaAs quantum well. It is demonstrated, that phase sensitive data for the rephasing and non‐rephasing modes are able to accurately provide the disorder induced broadening in a complex coupled system for each transition separately. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lasing in single ZnO nanorods after fs‐ and ns‐pulsed excitation
Authors: Fallert J. , Dietz R. J. B. , Zhou H. , Sartor J. , Klingshirn C. , Kalt H. 
Published: October 2008

AbstractIn this work we examine the lasing properties of single ZnO nanorods under ns‐ and fs‐pulsed excitation. By measuring the photoluminescence of individual nanorods excited by a single ns‐pulse we demonstrate that several stable lasing modes are emitted by the nanorod. In this quasi‐stationary excitation regime lasing up to room temperature can be achieved. Measurements of the temperature dependent laser threshold and of the spectral lasing region are presented. The excitation with fs‐pulsed excitation combined with a time resolved photoluminescence measurement gives furthermore an insight in the lasing dynamics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic analysis of high‐harmonic generation in semiconductor nanostructures
Authors: Golde Daniel , Meier Torsten , Koch Stephan W. 
Published: October 2008

AbstractA microscopic analysis of the emitted radiation of a semiconductor nanostructure after excitation with an extremely intense ultrashort laser pulse is presented. It is shown that the extreme nonlinear optical response is not sufficiently described by pure interband transitions but one has to include intraband effects as well.Numerical solutions of extended Bloch equations that include the coupled inter‐ and intraband dynamics are presented. For large excitation intensities, the intraband effects strongly modify the polarization dynamics and lead to a strong enhancement of high‐harmonic generation compared to pure interband dynamics. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impact of traveling phonon wave packets on the optical response of quantum dots
Authors: Huneke J. , Kuhn T. , Axt V. M. , Machnikowski P. 
Published: October 2008

AbstractThe influence of phonon wave packets created by the optical excitation of a quantum dot (QD) structure on four‐wave‐mixing (FWM) signals is analyzed theoretically. Two different structures are compared: a single QD in a half‐space geometry located close to the surface, where the emitted phonon wave packet after reflection at the surface reenters the QD and a pair of QDs in an infinite medium, where the phonon wave packet created in one QD travels across the other QD. Although the strain fields are very similar pronounced differences in the FWM polarizations are found.In the single QD system we observe clear signatures of the reflected wave packet in the FWM signal at positive delay times, which can also be observed in the time‐integrated FWM signal from an inhomogeneously broadened ensemble of such QDs. In the two QD case no signatures of the traveling wave packet are seen in the signal at positive delays and, consequently, in the ensemble signal. However, they are clearly seen in the FWM signal at negative delay times. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rapid classification of enzymes in cleaning products by hydrolysis, mass spectrometry and linear discriminant analysis
Authors: Beneito‐Cambra Miriam , Herrero‐Martínez José Manuel , Simó‐Alfonso Ernesto F. , Ramis‐Ramos Guillermo 
Published: October 2008

AbstractA method for the rapid classification of proteases, lipases, amylases and cellulases used as enhancers in cleaning products, based on precipitation with acetone, hydrolysis with HCl, dilution of the hydrolysates with ethanol, and direct infusion into the electrospray ion source of an ion‐trap mass spectrometer, has been developed. The abundances of the ([M+H]+ ions of the amino acids, from the hydrolysates of both the enzyme industrial concentrates and the detergent bases spiked with them, were used to construct linear discriminant analysis models, capable of distinguishing between the enzyme classes. For this purpose, the variables were normalized as follows: (A) the ion abundance of each amino acid was divided by the sum of the ion abundances of all the amino acids in the corresponding mass spectrum; (B) the ratios of pairs of ion abundances were obtained by dividing the ion abundance of each amino acid by each one of the ion abundances of the other 17 amino acids in the corresponding mass spectrum. Using normalization procedure B, excellent class‐resolution between proteases, lipases, amylases and cellulases was achieved. In all cases, enzymes in industrial concentrates and manufactured cleaning products were correctly classified with >98% assignment probability. Copyright © 2008 John Wiley & Sons, Ltd.
Perfume fingerprinting by easy ambient sonic‐spray ionization mass spectrometry: nearly instantaneous typification and counterfeit detection
Authors: Haddad Renato , Catharino Rodrigo Ramos , Marques Lygia Azevedo , Eberlin Marcos Nogueira 
Published: October 2008

AbstractPerfume counterfeiting is an illegal worldwide practice that involves huge economic losses and potential consumer risk. EASI is a simple, easily performed and rapidly implemented desorption/ionization technique for ambient mass spectrometry (MS). Herein we demonstrate that EASI‐MS allows nearly instantaneous perfume typification and counterfeit detection. Samples are simply sprayed onto a glass rod or paper surface and, after a few seconds of ambient drying, a profile of the most polar components of the perfume is acquired. These components provide unique and reproducible chemical signatures for authentic perfume samples. Counterfeiting is readily recognized since the exact set and relative proportions of the more polar chemicals, sometimes at low concentrations, are unknown or hard to reproduce by the counterfeiters and hence very distinct and variable EASI‐MS profiles are observed for the counterfeit samples. Copyright © 2008 John Wiley & Sons, Ltd.
A perception‐driven autonomous urban vehicle
Authors: Leonard John , How Jonathan , Teller Seth , Berger Mitch , Campbell Stefan , Fiore Gaston , Fletcher Luke , Frazzoli Emilio , Huang Albert , Karaman Sertac , Koch Olivier , Kuwata Yoshiaki , Moore David , Olson Edwin , Peters Steve , Teo Justin , Truax Robert , Walter Matthew , Barrett David , Epstein Alexander , Maheloni Keoni , Moyer Katy , Jones Troy , Buckley Ryan , Antone Matthew , Galejs Robert , Krishnamurthy Siddhartha , Williams Jonathan 
Published: October 2008

AbstractThis paper describes the architecture and implementation of an autonomous passenger vehicle designed to navigate using locally perceived information in preference to potentially inaccurate or incomplete map data. The vehicle architecture was designed to handle the original DARPA Urban Challenge requirements of perceiving and navigating a road network with segments defined by sparse waypoints. The vehicle implementation includes many heterogeneous sensors with significant communications and computation bandwidth to capture and process high‐resolution, high‐rate sensor data. The output of the comprehensive environmental sensing subsystem is fed into a kinodynamic motion planning algorithm to generate all vehicle motion. The requirements of driving in lanes, three‐point turns, parking, and maneuvering through obstacle fields are all generated with a unified planner. A key aspect of the planner is its use of closed‐loop simulation in a rapidly exploring randomized trees algorithm, which can randomly explore the space while efficiently generating smooth trajectories in a dynamic and uncertain environment. The overall system was realized through the creation of a powerful new suite of software tools for message passing, logging, and visualization. These innovations provide a strong platform for future research in autonomous driving in global positioning system–denied and highly dynamic environments with poor a priori information. © 2008 Wiley Periodicals, Inc.
Governance for sustainable development: a framework
Authors: van Zeijl‐Rozema Annemarie , Cörvers Ron , Kemp René , Martens Pim 
Published: October 2008

AbstractThis paper explores how two complex concepts, governance and sustainable development, can be linked in order to obtain a better understanding of their interactions. We argue that the many perspectives on sustainable development can be mapped on the continuum between ecological sustainability and quality of life. Likewise, the variety of modes of governance can be captured between hierarchical governance and deliberative governance, depending on the degree of involvement of societal actors. From these two typologies we derive a framework for analysis of governance for sustainable development. We realize that the typology is a significant simplification of the complex debates about sustainable development and governance, but it might help scientists and policy makers to explore relevant dimensions of modes of governance for sustainable development and for setting a framework for empirical analysis. The main conclusion of this paper is that the debate on governance for sustainable development will be clarified if the perspective on sustainable development and the mode of governance for achieving it are made more explicit.Problems that are now exclusively associated with sustainable development might well be problems of governance for sustainable development. Without making explicit what type of governance for sustainable development is pursued, miscommunication between stakeholders and mismatches of the approach with the instruments used could be the result, thus hampering progress in implementing sustainable development. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Sustainability in the Turkish retailing industry
Authors: Erol Ismail , Cakar Nigar , Erel Derya , Sari Ramazan 
Published: October 2008

AbstractRetailing is a diverse and dynamic industry offering a wide range of goods and services to consumers.There is also an increasing recognition that this corporate retail power is the driving force for the whole of the supply chain. Due to these facts, it is argued that retailing companies have a huge potential to impact on sustainability performance of national economies. In order to materialize this potential, performance in sustainability should be assessed, and evaluating sustainability performance of an industry requires developing a system of performance evaluation framework. In the context of sustainable development, selecting proper sustainability indicators are one of the most crucial steps to fulfill performance evaluations. Since there has been no attempt to develop proper sustainability indicators in retailing industry, this paper aims to select appropriate indicators for future evaluation of industrial sustainability performance for grocery retailing in terms of three sustainability aspects: social, environmental and economic. To this end, (1) a comprehensive analysis of the existing literature was done, (2) and Analytic Hierarchy Process/Weighted Additive model‐based table was developed to rank the indicators for each aspect, (3) the input for the tables was obtained from rapidly growing grocery retailing industry in Turkey by conducting surveys, and (4) using the average values of the tables, sustainability indicators for each aspect were ranked and the most appropriate ones were selected. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Commons and commoners: re‐examining community in common pool resources
Authors: Husain Zakir 
Published: October 2008

AbstractTraditional literature on common pool resources has shown that community management can produce sustainable outcomes, while simultaneously distributing benefits equitably within the resource community. However, its idealization of the resource community as a homogeneous and harmonious community has resulted in a failure to consider issues relating to the formation of resource communities, identity of the excluded sections and distribution of benefits within the geographical community. The paper argues that a study of individuals as members of coalitions will help to overcome this limitation. While there are a large number of possible coalitions that can be formed on the basis of alternative socio‐economic and cultural criteria, the resource community will ultimately be formed through the formation of a coalition that is stable against defection by any member. This coalition (corresponding to the core) maximizes net per capita benefits to its members.The arguments are supported by a field study of a water body in Bankura, India. Survey results show how the formation of caste‐based coalitions within a pluralistic community had led to the exclusion of some villagers from resource benefits. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
A mathematical model for lateral rotor dynamic analysis of soft mounted asynchronous machines
Authors: Werner U. 
Published: October 2008

AbstractThis paper shows a mathematical model for lateral rotor dynamic analysis of soft mounted asynchronous machines with sleeve bearings, due to harmonic and transient excitation. The simplified analytical model combines the electromagnetic, the rotor dynamic, and the specific characteristic of sleeve bearings, considering foundation stiffness and damping. Based on the shown mathematical description, it is possible to calculate the complex eigenvalues and eigenvectors, which describe the natural vibrations, the limit of stability, the relative shaft displacements, the bearing house vibrations and the dynamic foundation forces, due to rotor excitations and air gap torque excitations. Based on the simplified plane analytical model a three‐dimensional finite element model is also derived. The aim of this paper is not to replace a finite element calculation, but to show the mathematical coherences between rotor dynamic, electromagnetic and sleeve bearing characteristic for soft mounted asynchronous machines, considering foundation stiffness and damping, based on a simplified mathematical model.
Whole‐canopy nitrogen‐use efficiency of pioneer species in early secondary forest succession in Vietnam
Authors: van Kuijk Marijke , Anten Niels P. R. 
Published: October 2008

AbstractThe size hierarchy among plants during forest succession can be influenced by differences in nitrogen‐use efficiency (NUE). During succession, soil nitrogen availability decreases, which increases the importance for species to use nitrogen efficiently. We compare whole‐canopy‐NUE and its underlying traits among pioneer species in a tropical forest over the first years of succession. At the leaf level, potential photosynthetic NUE (PPNUE: light‐saturated photosynthetic rate/leaf N content) was partly positively correlated with species growth rate but not to species height. Canopy‐NUE differed two‐fold among species. The species with the highest PPNUE and growth rate but with a small stature had a high canopy‐NUE and the tallest species had a low canopy‐NUE. Differences in canopy‐NUE appeared to be largely determined by leaf life span (LLS) and nitrogen resorption. A high LLS or a high resorption resulted in a high mean residence time of nitrogen and thus a high canopy‐NUE. Canopy‐NUE of a species was different between successional stands that differed in age and thus in height, leaf‐area index, and resource availability. Thus, an increase in competitive pressure with succession did cause some changes in the use of nitrogen, except for one species. Species that are generally considered part of the same functional group (pioneer trees) can differ considerably in NUE and its underlying traits.
Formation of Insolubles in Palm Oil‐, Yellow Grease‐, and Soybean Oil‐Based Biodiesel Blends After Cold Soaking at 4 °C
Authors: Tang Haiying , De Guzman Rhet C. , Salley Steven O. , Ng K. Y. Simon 
Published: October 2008

AbstractThe insolubles formed in biodiesel blends can cause operation problems because they can plug the fuel lines and filters. The formation of insolubles in soybean oil (SBO‐), yellow grease (YG‐), and palm oil (PO‐) based biodiesel blends after cold soaking at 4 °C was investigated. PO‐based biodiesel blends displayed a much higher time to filter (TTF) and greater insoluble mass, compared to SBO‐, and YG‐based biodiesel blends. Fourier transform infrared (FTIR) spectra and gas chromatography‐flame ionization detector (GC‐FID) chromatograms indicated that PO‐based biodiesel insolubles can be attributed to monoglycerides, while SBO‐based biodiesel insolubles are due to steryl glucosides (SG). A simple analytical method for identification of SG in biodiesel samples was established by GC‐FID.