bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physical gelation of water‐borne thermosetting resins by percolation theory—Urea‐formaldehyde, melamine‐urea‐formaldehyde, and melamine‐formaldehyde resins
Authors: Celzard A. , Pizzi A. , Fierro V. 
Published: April 2008

AbstractPercolation and effective‐medium theories are applied for calculating the connectivity threshold of colloid particles of given shapes, observed during the physical gelation, distinguished from chemical gelation, of aminoplastic resins. The rigidity threshold, being the critical solid fraction at which a rigid network is first formed, was also calculated. For that purpose, it was assumed that the central forces that act between the colloidal particles and aggregates were not alone, thus corresponding to the case of physical gelation. It was shown that the observed change of morphology exhibited by such particles and aggregates as a function of time, from elongated to spherical, significantly delays the gel point. Consequently, the latter occurs only after a rather high fraction of solid phase (typically from 30 to 60%) is formed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 971–978, 2008
Epidermal growth factor receptor (EGFR) expression in prostatic adenocarcinoma after hormonal therapy: A fluorescence in situ hybridization and immunohistochemical analysis
Authors: Marks Rebecca A. , Zhang Shaobo , Montironi Rodolfo , McCarthy Ryan P. , MacLennan Gregory T. , Lopez‐Beltran Antonio , Jiang Zhong , Zhou Honghong , Zheng Suqin , Davidson Darrell D. , Baldridge Lee Ann , Cheng Liang 
Published: April 2008

AbstractBACKGROUNDThe progression of normal prostatic epithelium to androgen‐dependent cancer and, eventually, hormone‐refractory prostate cancer is a complex process involving many different growth regulatory signals. Activation of epidermal growth factor receptor (EGFR) has been implicated in prostate cancer cell growth.METHODSThis study was undertaken to investigate both amplification of EGFR gene by fluorescence in situ hybridization (FISH) and over‐expression of EGFR by immunohistochemical staining in prostate tissue from 71 patients treated by hormonal therapy.ResultsEGFR gene amplification was present in 1 of 71 tumors, and polysomy of chromosome 7 was present in 24 of 71 tumors. Immunohistochemically, EGFR expression was demonstrable in 57 of 71 tumors. Membranous immunostaining for EGFR was observed in >75% of tumor cells in 11% of cases, in 51–75% of tumor cells in 20% of cases, in 26–50% of tumor cells in 21% of cases, in 11–25% of tumor cells in 21% of cases, and in 1–10% of tumor cells in 7% of cases. No immunostaining for EGFR was seen in 20% of cases. There was no correlation between EGFR protein expression and gene amplification. There was also no correlation between EGFR expression and clinicopathological characteristics or clinical outcome.CONCLUSIONSWe found that EGFR gene expression was detectable in 35% of this large series of hormone‐treated prostate cancer, and that EGFR protein is frequently expressed in tissue from these patients. EGFR over‐expression may serve as a reasonable target for therapeutic intervention in this otherwise difficult to treat subset of prostate cancer. Prostate 68:919–923, 2008. © 2008 Wiley‐Liss, Inc.
Weak self‐association of human growth hormone investigated by nitrogen‐15 NMR relaxation
Authors: Jensen Malene Ringkjøbing , Kristensen Søren M. , Keeler Camille , Christensen Hans E. M. , Hodsdon Michael E. , Led Jens J. 
Published: April 2008

AbstractThe self‐association of human growth hormone (hGH) was investigated using 15N NMR relaxation. The investigation relies on the 15N R1 and R2 relaxation rates and the heteronuclear {1H}‐15N NOEs of the backbone amide groups at multiple protein concentrations. It is shown that the rotational correlation time of hGH in solution depends strongly on its concentration, indicating a significant degree of self‐association. The self‐association is reversible and the monomers in the aggregates are noncovalently linked. Extrapolation of the relaxation data to zero concentration predicts a correlation time of 13.4 ns and a rotational diffusion anisotropy of 1.26 for monomeric hGH, in agreement with the rotational diffusion properties estimated by hydrodynamic calculations. Moreover, the extrapolation allows characterization of the backbone dynamics of monomeric hGH without interference from self‐association phenomena, and it is found that hGH is considerably more flexible than originally thought. A concerted least‐squares analysis of the 15N relaxations and their concentration dependence reveals that the self‐association goes beyond a simple monomer‐dimer equilibrium, and that tetramers or other multimeric states co‐exist in fast exchange with the monomeric and dimeric hGH at sub‐millimolar concentrations. Small changes in the 1H and 15N amide chemical shifts suggest that a region around the C‐terminus is involved in the oligomer formation. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Quantum transport through nanowires: Ab initio studies using plane waves and supercells
Authors: Oetzel Björn , Preuss Martin , Ortmann Frank , Hannewald Karsten , Bechstedt Friedhelm 
Published: April 2008

AbstractWe present a numerical scheme for an ab initio implementation of the Landauer‐Büttiker theory for quantum transport by means of supercells and plane‐wave basis sets. The suggested method works entirely in k‐space which allows to circumvent the complicated projections onto tight‐binding Hamiltonians necessary in the more common real‐space approaches to quantum transport. As a first example for the usefulness of the method, we present DFT calculations of transmission functions for various one‐dimensional Au nanowires. The results are discussed with respect to future extensions to metal‐molecule‐metal nanojunctions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
White X‐ray microdiffraction analysis of defects, strain and tilts in a free standing GaN film
Authors: Barabash R. I. , Ice G. E. , Haskell B. A. , Nakamura Shuji , Speck J. S. , Liu W. 
Published: April 2008

AbstractA novel white‐beam microdiffraction analysis of defects, strains and tilts in a free standing m ‐plane GaN film grown via hydride vapor phase epitaxy is presented. It is shown that misfit dislocations are grouped within cell boundaries creating local lattice rotations (tilts) between the growing cells. Distribution of lattice rotations in the film is not homogeneous. Regions of large rotations are separated by low rotations regions. The dominating rotation axis is parallel [11$ \bar 2 $0] direction. High in plane shear stress component is observed along [0001]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Atom probe reveals the structure of InxGa1–xN based quantum wells in three dimensions
Authors: Galtrey M. J. , Oliver R. A. , Kappers M. J. , McAleese C. , Zhu D. , Humphreys C. J. , Clifton P. H. , Larsen D. , Cerezo A. 
Published: April 2008

AbstractThe three‐dimensional atom probe has been used to characterize InxGa1–xN based multiple quantum well structures emitting from the green to the ultra‐violet with sub‐nanometre resolution over a 100 nm field of view. The results show gross discontinuities and compositional variations within the UV‐emitting quantum well layers on a 20–100 nm length scale. We propose that these may contribute to the high efficiency of this structure. In addition, the analysis shows the presence of indium in the barrier layers of all the samples, whether or not there was an indium precursor present during barrier growth. The distribution of indium within the blue‐ and green‐emitting InxGa1–xN quantum wells is also analyzed, and we find no evidence that InxGa1–xN with a range of compositions is not a random alloy, and so rule out indium clustering as the cause of the reported carrier localization in these structures. The upper interface of each quantum well layer is shown to be rougher and more diffuse than the lower, and the existence of monolayer steps in the interfaces that could effectively localize carriers at room temperature is revealed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ga self‐interstitials in GaN investigated by ab‐initio calculations of the electronic g ‐tensor
Authors: Gerstmann U. , Seitsonen A. P. , Mauri F. 
Published: April 2008

AbstractIn GaN, an exceptionally important role is played by Ga‐interstitials being mobile at room temperature. Despite rather large formation energy, they have been observed in irradiated wurtzite‐GaN: at least two similar, but clearly distict ODEPR‐signals L5 and L6/L6* have been identified (via exceptionally large, nearly isotropic hyperfine splittings of about 4 GHz) as interstitial $ {\rm Ga}^{2+}_{\rm i} $ in two diffent lattice configurations. However, judging from experimental data and total energy calculations alone, the exact microscopic configuration remains unclear. In this theoretical work, the situation is elucidated by ab‐initio calculating the complete set of EPR parameters, hyperfine splittings as well as g ‐tensors, for the stable structural configurations of the Ga‐interstitial using a gauge‐including projector augmented plane wave (GI‐PAW) approach. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Space charged region in GaN and InN nanocolumns investigated by atomic force microscopy
Authors: Niebelschütz M. , Cimalla V. , Ambacher O. , Machleidt T. , Franke K.‐H. , Ristic J. , Grandal J. , Sánchez‐García M. A. , Calleja E. 
Published: April 2008

AbstractHigh quality InN and GaN nanocolumns of different length and diameter grown by molecular beam epitaxy (MBE) were electrically characterized directly and non‐destructively by Atomic Force Microscopy (AFM) as a function of the column diameter. The “exact” column diameter was determined from AFM images by Blind Tip Estimation (BTE) and subsequent image reconstruction in order to avoid artefacts due to the finite AFM tip radius. In GaN, the conductivity rises up to a “critical” diameter due to a depletion region at the surface of the nanocolumns and remains constant above. In contrast, the electron accumulation at the surface causes decreasing conductivity in InN nanocolumns with increasing diameter. Thus, the nanocolumn surface acts as the preferential conduction path. These facts prove that there is electron accumulation in as‐grown non‐polar InN surfaces, according to calculations of the Fermi level pinning in InN. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect‐related recombination in InGaN‐lasers
Authors: Schillgalies M. , Laubsch A. , Lutgen St. , Avramescu A. , Brüderl G. , Queren D. , Strauss U. 
Published: April 2008

AbstractWe have studied the influence of impurities in InGaN lasers. A magnesium background doping in InGaN quantum wells increases non‐radiative recombination significantly. Consequently, internal quantum efficiency decreases causing a large drop in laser performance. Electroluminescence measurements over a wide current and temperature range were used to study magnesium‐related radiative and non‐radiative recombination processes. Defect‐related processes are thermally activated. Quenching of EL‐intensity increases with magnesium concentration and is attributed to increased non‐radiative recombination as a result of thermal release of bound holes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InN/In2O3 heterostructures
Authors: Wang Ch. Y. , Cimalla V. , Lebedev V. , Kups Th. , Ecke G. , Hauguth S. , Ambacher O. , Lozano J. G. , Morales F. M. , González D. 
Published: April 2008

AbstractCubic (c‐) InN is predicted to possess superior electronic properties for device applications, while c‐In2O3 is an excellent candidate as gate material for InN based high‐frequency field effect transistors. In this paper, the epitaxial growth of the InN/In2O3 and In2O3/InN heterosystems was investigated. High‐quality c‐InN (001) was deposited on (001) In2O3 tem‐ plate, while single crystalline c‐In2O3 was epitaxially grown on hexagonal InN (0001). The epitaxial relationship of the heterosystems was determined. Phenomenological models of the nucleation and of an atomic arrangement at the interface are proposed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High temperature behaviour of GaN HEMT devices on Si(111) and sapphire substrates
Authors: Cuerdo R. , Calle F. , Braña A. F. , Cordier Y. , Azize M. , Baron N. , Chenot S. , Muñoz E. 
Published: April 2008

AbstractA study of the high temperature DC performance of nitride high electron mobility transistors (HEMTs) on Si(111) and sapphire substrates with different gate lengths is reported. All single gate transistors decrease their drain current (ID) and transconductance (gm) from room temperature (RT) up to 350 °C, mainly due to the electron mobility reduction by optical phonon scattering. At RT, HEMTs on Si(111) present higher ID and gm than transistors on sapphire, probably related to their lower self‐heating. As devices are heated, these differences tend to disappear, indicating that the substrate thermal conductivity becomes less important. Compact devices have low relative reduction in ID and gm values with temperature, since shorter gate lengths lead to higher fields under the gate and lower temperature dependence of the drift velocity. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fabrication and stress relief modelling of GaN based MEMS test structures grown by MBE on Si(111)
Authors: Sillero E. , López‐Romero D. , Bengoechea A. , Sánchez‐García M. A. , Calle F. 
Published: April 2008

AbstractThe fabrication of III‐N MEMS test structures, such as cantilevers, beams and stress‐pointers, and the modelling of their deformation due to residual stress relief, is presented. GaN and AlGaN/GaN structures were fabricated, either with one end and both ends clamped to the Si substrate (asymmetrical and symmetrical mechanical boundary conditions, respectively). The residual stress in the III‐N layer was measured by photoluminescence and X‐ray diffraction, and the stress relief induced deformation was analysed by a finite element method model. The deformations of the MEMS structures were used to calculate both the residual strains and the Young's modulus of the material. One‐end‐clamped structures suffer from large deformations due to the uneven stress relaxation. During micromachining, the relaxation induces large upward buckling, as measured for fabricated devices and fitted by the FEM model. Two‐end‐clamped structures were also studied using different topologies and under‐etching lengths of the clamped region. It is concluded that the deformation of such structures may be reduced with symmetrical mechanical boundary conditions and a small under‐etched clamping region compared to the device dimensions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical study of O2 adsorption and CO2 formation in bimetallic dimer clusters Au‐M
Authors: Pacheco‐Ortín Sandy Maria , Agacino‐Valdés Esther , de la Mora Pablo 
Published: April 2008

AbstractCation, anion, and neutral states in Au‐M dimer clusters have been calculated as a way to study in a small model, the Au‐sites, and M‐sites in a supported nanoparticle (NP). These charged states can be formed during a charge transfer process between certain atoms of the NP with the atoms of the support or simply with cationic or anionic defects. These results can be important to evaluate in a preliminary way, the relation between the activity of the Au‐sites and M‐sites because of its charge and the effectiveness of the adsorption of O2, and the subsequent interaction between adsorbed O2 and CO through a Langmuir‐Rideal unimolecular mechanism. For the O2 adsorption over Au active site, the Au‐Ir, Au‐Au, Au‐Ag, Au‐Pd, and Au‐Cu dimers yielded negative binding energies in all the charge states considered (anion, cation, and neutral); when M active site was considered, Au‐Cu and Au‐Ag dimers also gave negative values of binding energies in all the charged states. Furthermore, there was observed that electron rich Au‐sites are essential in the O2 adsorption. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
A group of 3D graphical representation of DNA sequences based on dual nucleotides
Authors: Cao Zhi , Liao Bo , Li Renfa 
Published: April 2008

AbstractBased on chemical properties of the neighboring dual nucleotides, we reduce a DNA sequence into four 3D graphical representations. Associating with the eigenvalues of the introduced covariance matrix and the introduced measure of similarity, we introduce an approach to make similarity analysis of DNA sequence. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Interfacial properties of thermally oxidized Ta2Si on Si
Authors: Pérez‐Tomás A. , Jennings M. R. , Mawby P. A. , Millán J. , Godignon P. , Montserrat J. , Rossinyol E. , Vennegues P. , Stoemenos J. 
Published: April 2008

AbstractMany refractory metal silicides have received great attention due to their potential for innovative developments in the silicon‐based microelectronic industry. However, tantalum silicide, Ta2Si, has remained practically unnoticed since its successful application in silicon carbide technology as a simple route for a high‐k dielectric formation. The thermal oxidation of Ta2Si produces high‐k dielectric layers, (OTa2Si)‐based on a combination of Ta2O5 and SiO2. In this work, we investigate the interfacial properties of thermally oxidized (850–1050 °C) Ta2Si on commercial silicon substrates. The implications of diffusion processes in the dielectric properties of an oxidized layer are analyzed. In particular, we observe migration of tantalum pentoxide nanocrystals into the substrate with increasing oxidation temperature. An estimation of the insulator charge and interfacial OTa2Si/Si trap density is also presented. Copyright © 2008 John Wiley & Sons, Ltd.
Learning how to restructure: absorptive capacity and improvisational views of restructuring actions and performance
Authors: Bergh Donald D. , Lim Elizabeth Ngah‐Kiing 
Published: April 2008

AbstractThis paper examines the role of learning in corporate restructuring. Drawing from two viewpoints of organizational learning, absorptive capacity and organizational improvisation, we examine whether experience with corporate restructuring modes (sell‐offs, spin‐offs) influences subsequent restructuring and financial performance. Consistent with an absorptive capacity view, cumulative and repetitive experience with sell‐offs was related to the adoption of an ensuing sell‐off and to higher performance. Conversely, and consistent with an organizational improvisation view, short‐term and contemporaneous experience with spin‐offs was related to the subsequent use of spin‐offs and to increases in financial performance. The findings contribute to a dynamic explanation of corporate restructuring and its influence on financial performance, illustrate differences between learning in a repetitive situation and learning when repetition is rare, and indicate when absorptive capacity and organizational improvisational views are most profitable. Overall, these findings show that different kinds of restructuring experiences were associated with different modes of restructuring and performance records. Considered collectively, the organizational learning perspective offers insights into why some corporate restructuring strategies appear as intentional and deliberate actions while others resemble more spontaneous and simultaneous responses. Copyright © 2008 John Wiley & Sons, Ltd.
Environmental risk management and the cost of capital
Authors: Sharfman Mark P. , Fernando Chitru S. 
Published: April 2008

AbstractOur study of 267 U.S. firms shows that improved environmental risk management is associated with a lower cost of capital. Our findings provide an alternative perspective on the environmental‐economic performance relationship, which has been dominated by the view that improvements in economic performance stem from better resource utilization. Firms also benefit from improved environmental risk management through a reduction in their cost of equity capital, a shift from equity to debt financing, and higher tax benefits associated with the ability to add debt. These findings help build better theory regarding the outcomes of strategic improvements in environmental risk management. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of Gas Flow Ratio in PE‐CVD Process on Mechanical Properties of Silicon Nitride Film
Authors: Oh Hyun‐Jin , Isono Yoshitada , Namazu Takahiro , Saito Yoshihiro , Yamaguchi Akira 
Published: April 2008

AbstractThis paper investigates the influence of gas flow ratio in the preparation of submicron‐thick silicon nitride (SiNx) films on their elastic properties. SiNxfilms with a thickness ranging from 0.14 to 0.69 µm were deposited by plasma‐enhanced chemical vapor deposition (PE‐CVD) onto 10‐µm‐thick single‐crystal silicon (SCS) specimens by changing the gas flow ratio of monosilane (SiH4) to ammonia (NH3) to nitrogen (N2). A uniaxial tensile tester operated under an atomic force microscope (AFM) characterized the Young's modulus of SiNxfilms and the fracture strength of SiNx/SCS laminated specimens. The Young's modulus of SiNxfilms ranged from 99.5 to 144.3 GPa, which increased with the gas flow ratio but was independent of the film thickness. Nano‐indentation tests were also carried out to examine the Poisson's ratio of SiNxfilms in addition to the tensile tests. The Poisson's ratio was found to be 0.19 to 0.27, on average. Auger spectroscopy revealed that an increase of the atomic content ratio of nitrogen (N) to silicon (Si) in SiNxfilms yielded higher elastic constants of the films. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Contrast Improvement Method for Monochrome Images Based on the Ratio of Local Variances of Gray levels
Authors: Saitoh Fumihiko 
Published: April 2008

AbstractWhen the contrast of a captured image is not good, a method for contrast improvement may be useful. Especially, liner transform (LT) of gray levels and the histogram equalization (HE) method are well known as general methods. However, an effective contrast improvement does not always work, or an unnatural output is often generated by these methods. This paper proposes a method for contrast improvement to generate an image with medium contrast between those obtained by LT and HE. An input image is separated into an object area and a background area by every pixel. The variance of gray levels in the local area is used for measuring the local contrast. The ratio of the variances of gray levels in these areas is evaluated to determine the relative weights of LT and HE. The experimental results show that output images with higher contrast than that by LT and with less saturation of brightness and less noise than those by HE were generated by the proposed method. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Running Test of Contactwire‐less Tramcar Using Lithium Ion Battery
Authors: Ozawa Hironori , Ogihara Takashi 
Published: April 2008

AbstractThe basic specification of lithium ion battery‐type tramcar was established using DC600V‐type tramcar with a weight of 40 t. Forty five kilo Watt hour of manganese‐type lithium ion battery was used. The running test was carried out for the first time in Japan in the business line. The relation between running time and voltage, current and integrating watt was investigated in detail. The tramcar was run when the lithium ion battery module was discharged between 660 and 480 V. On one charge, the tramcar could run for about 25 km. The mileage of contactwire‐less tramcar improved two times that of tramcar. The running performance of contactwire‐less tramcar was equivalent to the tramcar. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.