bluuebunny/crossref_metadata_2025_split huggingface dataset:
Epitaxial lateral overgrowth of GaN on 4 inch Si(111) by MOVPE
Authors: Cheng Kai , Motsnyi V. , Leys M. , Degroote S. , Sijmus B. , Germain M. , Borghs G. 
Published: April 2008

AbstractEpitaxial Lateral Overgrowth (ELOG) of GaN on 4 inch silicon(111) substrates by MOVPE was investigated in this study. ELOG was performed on a GaN template with a couple of AlGaN intermediate layers (IL) on an AlN nucleation layer. The AlGaN ILs supply compressive stress to the top GaN template and thereafter to the ELOG layer. Consequently, layer cracking is minimized. Two masks were used in this work: a 2 inch wagon wheel mask and a 4 inch mask with parallel stripes of various filling factors and periods. The filling factor is varied from 0.33 to 0.7. The periodic spacing is in the range of 6 μm to 10 μm. Temperature, V/III ratio, pressure and stripe orientation were optimized to achieve fastest lateral growth rate. The highest lateral to vertical ratio can be more than 4. A fully coalesced layer within the critical thickness for a crack‐free layer was achieved on 4 inch silicon substrates. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improvement of surface roughness and reduction of threading dislocation density in AlN/AlGaN templates on sapphire by employing trimethylaluminum pulsed supply growth
Authors: Noguchi Norimichi , Ohashi Tomoaki , Kamata Norihiko , Hirayama Hideki 
Published: April 2008

AbstractWe fabricated high‐quality AlN/AlGaN templates, which are applicable to ultraviolet (UV) emitters on sapphire, by using a trimethylaluminum (TMAl) pulsed‐supply growth method. We succeeded in achieving a dramatic improvement in the surface roughness of AlN/AlGaN layer by introducing a short‐period pulsed supply of TMAl during the growth intervals of a ‘standard’ AlGaN growth regime. We speculate that the improvement in surface roughness is due to the realization of stable group III (+c) polarity by the growth of an Al‐rich surface. In addition, we have found that this method is effective for reducing threading dislocation densities (TDD). The TDD was reduced from 2.9×109 to 1.1×109 cm–2 by introducing the TMAl pulsed supply growth. We fabricated a 350 nm‐band InAlGaN multi‐quantum well (MQW) UV light‐emitting diode (LED) on an AlN/AlGaN template formed by the TMAl pulsed supply method, and obtained an output power of 1.95 mW under room temperature (RT) CW operation. The output power of the LED was increased by a factor of 1.7 by introducing the TMAl pulsed supply method. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dislocation related defect states in GaN irradiated with 1 MeV electron‐beam
Authors: Lee Dong Uk , Ha Lim‐Kyoung , Kim Jin Soak , Kim Eun Kyu , Koh Eui Kwan , Han Il Ki 
Published: April 2008

AbstractUndoped GaN layers with thickness of 278 µm were grown by hydride vapor phase epitaxy method. The samples with different threading dislocation densities of 9.0x106 cm–2 and 7.2x106 cm–2 were irradiated by electron‐beam with the energy of 1 MeV and dose of 1x1015 cm–2. The defect states of the samples after electron beam irradiation were characterized by deep level transient spectroscopy measurement. After the electron‐beam irradiation, the the defects appeared to states with the activation energies of 0.61 eV, 0.30 eV, and 0.57 eV. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The CL emission observation of the InGaN/GaN MQWs V shaped pits with different superlattices underlayers
Authors: Lai W. C. , Huang Y. S. , Yen Y. W. , Sheu J. K. , Hsueh T. H , Kuo C. H. , Chang S. J. 
Published: April 2008

AbstractWe prepared InGaN/GaN multiquantum wells (MQWs) with InGaN/GaN strained layer superlattice (SLS) underlayer and with GaN/AlGaN SLS underlayer to create different V‐shaped pits. It was found that pit density became smaller while pit depth and pit diameter both became larger, as compared to the sample without SLS. It was also found that sample surface became rougher with the SLS. Furthermore, it was found that light output intensities observed from the samples with SLS were stronger. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface and boundary‐layer modelling for the Mars Exploration Rover sites
Authors: Savijärvi Hannu , Kauhanen Janne 
Published: April 2008

AbstractThe boundary layer and surface temperatures at the two Mars Exploration Rover sites (Spirit at Gusev Crater; Opportunity at Meridiani plains) were simulated with a soil–atmosphere column model and compared with the observations retrieved from scans through the thin and dusty CO2 atmosphere by the miniature thermal emission spectrometers (mini‐TES) onboard the two rovers.The quite repetitive diurnal temperature cycle is reproduced fairly well by the model. In particular the surface temperatures appear to be well simulated. They are strongly controlled by the downwelling solar and thermal radiation from the atmosphere. Turbulent heat fluxes are small compared with net radiation, so they are relatively unimportant in the surface heat budget. Turbulence is nevertheless important in transferring heat convectively up from the radiatively heated and strongly superadiabatic daytime atmospheric surface layer. A strong surface inversion develops during each night.The annual cycle is also well simulated, except that during the warm and dusty perihelion/summer period the temperatures appear overestimated by the model. This may be due to inaccurate handling of dust in the model, or to dust accumulation on the instrument optics, or perhaps both. The annual temperature cycle demonstrates the large eccentricity of Mars' orbit, the seasonal effects and the variable dustiness of the atmosphere. Copyright © 2008 Royal Meteorological Society
MP2, DFT‐D, and PCM study of the HMB–TCNE complex: Thermodynamics, electric properties, and solvent effects
Authors: Kysel Ondrej , Budzák Šimon , Medveď Miroslav , Mach Pavel 
Published: April 2008

AbstractGeometry, thermodynamic, and electric properties of the π‐EDA complex between hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) are investigated at the MP2/6‐31G* and, partly, DFT‐D/6‐31G* levels. Solvent effects on the properties are evaluated using the PCM model. Fully optimized HMB–TCNE geometry in gas phase is a stacking complex with an interplanar distance 2.87 × 10−10 m and the corresponding BSSE corrected interaction energy is −51.3 kJ mol−1. As expected, the interplanar distance is much shorter in comparison with HF and DFT results. However the crystal structures of both (HMB)2–TCNE and HMB–TCNE complexes have interplanar distances somewhat larger (3.18 and 3.28 × 10−10 m, respectively) than our MP2 gas phase value. Our estimate of the distance in CCl4 on the basis of PCM solvent effect study is also larger (3.06–3.16 × 10−10 m). The calculated enthalpy, entropy, Gibbs energy, and equilibrium constant of HMB–TCNE complex formation in gas phase are: ΔH0 = −61.59 kJ mol−1, ΔS = −143 J mol−1 K−1, ΔG0 = −18.97 kJ mol−1, and K = 2,100 dm3 mol−1. Experimental data, however, measured in CCl4 are significantly lower: ΔH0 = −34 kJ mol−1, ΔS = −70.4 J mol−1 K−1, ΔG0 = −13.01 kJ mol−1, and K = 190 dm3 mol−1. The differences are caused by solvation effects which stabilize more the isolated components than the complex. The total solvent destabilization of Gibbs energy of the complex relatively to that of components is equal to 5.9 kJ mol−1 which is very close to our PCM value 6.5 kJ mol−1. MP2/6‐31G* dipole moment and polarizabilities are in reasonable agreement with experiment (3.56 D versus 2.8 D for dipole moment). The difference here is due to solvent effect which enlarges interplanar distance and thus decreases dipole moment value. The MP2/6‐31G* study supplemented by DFT‐D parameterization for enthalpy calculation, and by the PCM approach to include solvent effect seems to be proper tools to elucidate the properties of π‐EDA complexes. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
Initial formation of contact layers on Ni/SiC samples studied by XPS
Authors: Pérez‐García S. A. , Cao Y. , Nyborg L. 
Published: April 2008

AbstractThis study deals with the quantitative assessment of the coverage and thickness of Ni silicide films formed during annealing of SiC substrates with sputtered thin films of Ni. The analytical approach involves the use of XPS and depth profiling by means of successive ion etchings and XPS analyses. For either 3 or 6 nm initial Ni film thickness, a 10 nm Ni2Si product is formed. On top of this product, the C released is accumulated in a very thin (1–2 nm) film. In neither case, the Ni2Si covers the whole surface, although the coverage is almost complete (∼90%) in the latter case. For the greater initial Ni‐film thickness of 17 nm, the thickness of the Ni2Si product corresponds well to the value of 25 nm expected from the Ni/Ni2Si stoichiometric relationship. This thickness is significantly greater than a critical level and the film covers the whole surface. Carbon is similarly accumulated in a very thin layer on the top surface, although the major part of C (∼70%) is found inside the main reaction product layer. Copyright © 2008 John Wiley & Sons, Ltd.
Structuring interorganizational cooperation: the role of economic integration in strategic alliances
Authors: Luo Yadong 
Published: April 2008

AbstractThis study addresses a new dimension that describes interdependence between alliance members, namely, economic integration–the extent to which resources contributed by different alliance members and subsequent operations using these resources are effectively blended into an alliance's value chain to the point where if one member withdraws, the remaining member(s) suffer great loss. We posit that economic integration has a linear positive effect on alliance stability but a curvilinear (diminished) effect on alliance profitability. Moreover, when economic integration is stronger, other dyadic variables such as interparty trust, joint governance and procedural justice will have a greater effect on alliance performance. Analysis of 198 cross‐cultural strategic alliances in an emerging market generally supports these propositions. Copyright © 2008 John Wiley & Sons, Ltd.
The accentuated CEO career horizon problem: evidence from international acquisitions
Authors: Matta Elie , Beamish Paul W. 
Published: April 2008

AbstractWe develop a conceptual model of the career horizon problem of CEOs approaching retirement and discuss its implications on firm risk taking, specifically in engagement in international acquisitions. Based on prospect theory and agency theory, we emphasize the legacy conservation and wealth preservation concerns of CEOs and investigate how their holdings of in‐the‐money unexercised options and firm equity accentuate or mitigate the career horizon problem. The model is tested in the context of international acquisitions with a sample of 293 U.S. firms over a five‐year period (1995–1999). We find that a longer CEO career horizon is associated with a higher likelihood of international acquisitions. We also find that CEOs nearing retirement with high levels of in‐the‐money unexercised options and equity holdings are less likely to engage in international acquisitions than CEOs with low levels of in‐the‐money options and equity holdings. The study raises important considerations about the implications of CEOs' equity and in‐the‐money option holdings on firm risk taking at various stages of their career horizon. Copyright © 2008 John Wiley & Sons, Ltd.
Asymmetric interactions between foreign and domestic banks: effects on market entry
Authors: Li Jiatao 
Published: April 2008

AbstractAn inverted U‐shaped relationship is thought to exist between the number of firms entrenched in a market and the rate of new entrants. This study examined early and late entry by foreign and U.S. banks into the California market following a deregulation in the banking industry in the early 1980s. The study was designed to elucidate the competitive interactions between foreign and domestic banks. Specifically, what response did the entry of foreign banks elicit from domestic banks and what influence did the entry of domestic banks exert on the evolution of the foreign banks in the market. Data covering the period from 1979 to 1988 demonstrate that the density of foreign banks operating in the market had a U‐shaped relationship with the rate of entry of U.S. banks, supporting the argument that foreign investment can encourage the expansion of domestic banks. Although foreign banks were not an obstacle to domestic bank entries, the presence of domestic banks deterred the entry of foreign banks. Copyright © 2008 John Wiley & Sons, Ltd.
A bargaining perspective on strategic outsourcing and supply competition
Authors: De Fontenay Catherine C. , Gans Joshua S. 
Published: April 2008

AbstractThis article considers the outsourcing choice of a downstream firm with its own upstream production resources or assets. The novelty of the approach is to consider the outsourced function as involving resources consistent with the resource‐based view of the firm. From a bargaining perspective, we characterize a downstream firm's decision whether to outsource to an independent or to an established upstream firm. In so doing, the downstream firm faces a trade‐off between lower input costs afforded by independent competition, and higher resource value associated with those who can consolidate upstream capabilities. We show that this trade‐off is resolved in favor of outsourcing to an established firm. Copyright © 2008 John Wiley & Sons, Ltd.
Design of A Soft X‐ray Source with Periodic Microstructure Using Resonance Transition Radiation for Tabletop Synchrotron
Authors: Sugano Koji , Sun Weiyu , Tsuchiya Toshiyuki , Tabata Osamu 
Published: April 2008

AbstractA soft X‐ray source with a periodic aluminum multilayer structure with vacuum layers in between for tabletop synchrotrons with low‐energy electrons was designed, and the dependence of radiation performance on structural parameters was clarified using a theoretical calculation of the resonance transition radiation. A photon density of 1 keV pr incident electron was calculated by optimizing the thickness of the aluminum and vacuum layers. Furthermore, the designed structure was fabricated by a microfabrication technique. The effects of dimensional error on the photon density are discussed on the basis of the calculated results and the prototype structure of a 6‐MeV synchrotron. It is clarified that dimensional errors of 1.5% in Al layers and of plus or minus a few dozen nanometers in the vacuum layers are negligible in obtaining a photon density of more than 90% of the maximum value. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Low‐Noise Fully Differential Amplifiers Using JFET‐CMOS Integration Technology for Smart Sensors
Authors: Takao Hidekuni , Vatedka Radhakrishna , Ito Yoshiaki , Komakine Fumihito , Serge Kolelas , Sawada Kazuaki , Ishida Makoto 
Published: April 2008

AbstractIn this paper, CMOS‐based low‐noise amplifiers with JFET‐CMOS technology for high‐resolution sensor interface circuits are presented. A differential difference amplifier (DDA) configuration is employed to realize differential signal amplification with very high input impedance, which is required for the front‐end circuit in many sensor applications. Low‐noise JFET devices are used as input pair of the input differential stages or source‐grounded output load devices, which are dominant in the total noise floor of DDA circuits. A fully differential amplifier circuit with pure CMOS DDA and three types of JFET‐CMOS DDAs were fabricated and their noise performances were compared. The results show that the total noise floor of the JFET‐CMOS amplifier was much lower compared to that of the pure CMOS configuration. The noise‐reduction effect of JFET replacement depends on the circuit configuration. The noise reduction effect by JFET device was maximum of about − 18 dB at 2.5 Hz. JFET‐CMOS technology is very effective in improving the signal‐to‐noise ratio (SNR) of a sensor interface circuit with CMOS‐based sensing systems. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
A Superhydrophobic Microvalve for Manipulating Microliquids Containing Biological Molecules
Authors: Yasuda Takashi , Ishizuka Katsutoshi , Ezoe Mika 
Published: April 2008

AbstractThis paper presents a novel microvalve including a superhydrophobic surface that inhibits adsorption of a liquid that contains biological molecules. This microvalve was fabricated by anodizing the Si surface of a microchannel wall and making the channel surface partially superhydrophobic. The superhydrophobicity could be modified by changing the anodization time and current density during the anodization process. Experiments using a cell‐culture medium showed that the fabricated microvalve successfully opened/closed repeatedly by applying a positive/negative pressure from the inlet, and that it could be opened within 0.5 s by an inlet pressure of more than 9 kPa. Also, we could continue switching the microvalve at 1 Hz for about 3 h (10 800 switching) while adjusting the required inlet pressures, which increased with time. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
MEMS‐based Air Turbine with Radial‐inflow Type Journal Bearing
Authors: Tanaka Shuji , Miura Yuichi , Kang Piljoong , Hikichi Kousuke , Esashi Masayoshi 
Published: April 2008

AbstractA microelectromechanical‐systems (MEMS)‐based air turbine with a new bearing system was designed, fabricated, and evaluated. The bearing system uses a radial‐inflow type journal bearing and a single‐sided hydroinertia thrust bearing. To fabricate the radial‐inflow type journal bearing, cavity‐through deep reactive ion etching (DRIE) in conjunction with silicon‐to‐silicon direct bonding was used. Two etched silicon substrates were directly bonded, and then the bonded silicon substrates were etched by DRIE through the inside cavities. A maximum rotation speed of 95 000 rpm was achieved. The measured and calculated frequency responses of the rotor‐bearing system suggest that the maximum rotation speed was probably limited by the pitching mode resonance. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Electrostatically Controlled, Pneumatically Actuated Microvalve with Low Pressure Loss
Authors: Satoh Daisuke , Tanaka Shuji , Esashi Masayoshi 
Published: April 2008

AbstractThis paper describes a microvalve to control liquefied gas in a micro fuel reforming system. To realize both high pressure leak tolerance and low pressure loss, a main valve is pneumatically actuated by the pressure of the liquefied gas itself, and its pneumatic actuation is controlled by two electrostatic sub‐valves. The fabricated microvalve was tested in terms of pressure loss in the open state, leakage in the closed state, driving voltage, and response time. The pressure loss was close to the theoretical value, which was sufficiently low for the application. The apparent leakage was not detected until the input pressure reached 150 kPa (gage). The driving voltage of the sub‐valve was 30‐40 V. The response time from the closed to the open state is expected to be less than 200 ms. The experimental results suggest that all the required functions such as low pressure loss, electrostatic actuation and leak proof operation can be realized. © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Quantitative Evaluation of Corrosive Sulfur in Electrical Insulating Oil
Authors: Ito Takashi , Morishima Yoshiyuki 
Published: April 2008

AbstractThis paper presents quantitative evaluation method of corrosive sulfur in insulating oil. The level of corrosion on copper strip which was aged in insulating oil is expressed numerically by the amount of sulfur on it. Since X‐ray strength by wave length dispersive X‐ray (WDX) and measurement value of sulfur on copper strip by titration show good correlation, the amount of sulfur can be obtained rapidly only by WDX. The performance of passivator such as BTA or Irgamet39 was quantitatively evaluated by WDX. The evaluation of life of passivator was also achieved. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Analyzing Method of Temporal Brain Activation in fMRI Measurements
Authors: Fukami Tadanori , Nakajima Natsuki , Shimada Takamasa , Ishikawa Fumito , Ishikawa Bunnoshin , Saito Yoichi 
Published: April 2008

AbstractIn this paper, we propose a method to acquire the temporal changes of activations by combining a slide of the analysis time window and t‐value. An advantage of this method is that it can acquire rough changes of the activated areas even with data having low time resolution. Nine normal subjects participated in the study of the visual oddball paradigm, which consisted of a random series of 30 targets and 30 control stimuli. Here, the subjects were instructed to push a button as the go‐task when a target stimulus occurred. We investigated the activated area in three types of analysis time sections: from stimulus onset to 5 s after the stimulus (time section A; TS‐A); from 5 to 10 s (TS‐B); and from 10 to 15 s (TS‐C). We also investigated the temporal change of the t‐value between go and no‐go responses in blood oxygenation level dependent (BOLD) signals. In this study, we picked up the following eight representative areas corresponding with previous reports: left primary motor area and left somatosensory motor area, supramarginal gyri (SMG), right superior parietal lobule, right inferior frontal gyrus, cerebellum (cerebellar tonsil), and right medial frontal gyrus. Among them, the left primary motor area and left somatosensory motor area showed prominent activation (t > 10) in TS‐A and TS‐B, respectively. Activity at the left supramarginal gyrus decreased gradually with time, and right insula showed constant activation through all time sections.We could see various patterns on temporal activation at different positions in the brain. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Fine‐Needle Aspiration Biopsy of Benign Thyroid Nodules: An Evidence‐Based Review
Authors: Lundgren Catharina Ihre , Zedenius Jan , Skoog Lambert 
Published: April 2008

AbstractBackgroundSince the development of fine‐needle aspiration biopsy (FNAB) techniques, preoperative diagnosis and subsequent strategies for patient treatment have changed and evolved greatly. This is true also for thyroid FNAB: the vast majority of thyroid nodules are benign, and hence do not necessarily require surgical treatment.MethodsA comprehensive Medline and Cochrane Library search was performed evaluating FNAB in the thyroid. In the last decade more than 400 articles on the subject have been published. Data in relation to the experience with FNAB at the Karolinska University Hospital since its introduction were also reviewed.ResultsThe development of FNAB since the 1960s at the Karolinska University Hospital is described. During the period 1992–1996 the accuracy of the clinical routine was evaluated by studying the outcomes of almost 4,000 FNAs of the thyroid. The results were good, with only a few false‐negative and false‐positive results, but the problem of differentiating follicular adenoma from follicular carcinoma remained a significant problem. The use of immunological analysis has greatly increased the possibility of obtaining valuable information on cellular characteristics.ConclusionA successful FNAB service rests on several factors, and the importance of clinical conferences between all specialists involved in the diagnosis and treatment of patients with thyroid disorders cannot be overemphasized. At the Karolinska University Hospital there are weekly conferences where patients are discussed both pre‐ and postoperatively. These conferences lead to optimal interaction between the different specialists and, most important, substantial improvement in the clinical management of patients with thyroid disorders.