bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐efficiency yellow light‐emitting diodes grown on sapphire (0001) substrates
Authors: Hashimoto Rei , Hwang Jongil , Saito Shinji , Nunoue Shinya 
Published: February 2014

AbstractHigh‐efficiency yellow InGaN‐based light‐emitting diodes (LEDs) were grown by metal‐organic chemical vapor deposition on conventional c‐plane sapphire (0001) substrates. Optimization of the growth temperature of barrier layers eliminated surface inclusions and resulted in improved output properties of the fabricated yellow LEDs. They exhibited a high output power of 8.4 mW and external quantum efficiency of 19.3% for yellow light (570 nm) at an injection direct current of 20 mA. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Thermally robust RuOx Schottky diodes and HEMTs on III‐nitrides
Authors: Kyaw Lwin Min , Saju Aju Abraham , Liu Yi , Bera Milan Kumar , Singh Sarab Preet , Tripathy Sudhiranjan , Chor Eng Fong 
Published: February 2014

AbstractThe potential usage of thermally robust RuOx Schottky contacts in III‐nitride‐based Schottky diodes and high electron mobility transistors (HEMTs) has been investigated. RuOx is deposited on nitride surface by sputtering Ru in Ar/O2 ambient. The influence of post sputtering annealing ambient and temperature on the characteristics of RuOx Schottky diodes on n‐type GaN on Si(111) substrate is addressed. We also report the comparative study of thermal stability between RuOx and Ni/Au Schottky diodes on InxAl1‐xN/GaN on Si(111) substrate in terms of the reverse bias leakage current and Schottky barrier height (SBH). RuOx contact shows a higher SBH of 1.24 eV and a lower leakage current of ∼10‐5 Acm‐2 (∼four orders of magnitude lower than that of Ni/Au) on InxAl1‐xN/GaN at –40 V after annealing at 800 oC in N2. In addition, RuOx Schottky gate HEMT on InxAl1‐xN/GaN on Si(111) substrate has shown a low gate leakage current of ∼6×10‐8 A/mm at ‐8 V after annealing at 700 oC in N2 for 1 minute. The lower gate leakage current has resulted in a transistor ON/OFF current ratio of ∼105. The maximum transconductance and ON‐resistance achieved by such HEMTs are about 0.18 S/mm and 8.33 Ωmm, respectively, for a gate length of 1.5 µm. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Improved theoretical model of InN optical properties
Authors: Ferreira da Silva A. , Chubaci J. F. D. , Matsuoka M. , Freitas J. A. , Tischler J. G. , Baldissera G. , Persson C. 
Published: February 2014

AbstractThe optical properties of InN are investigated theoretically by employing the projector augmented wave (PAW) method within Green's function and the screened Coulomb interaction approximation (GWo). The calculated results are compared to previously reported calculations which use local density approximation combined with the scissors‐operator approximation. The results of the present calculation are compared with reported values of the InN bandgap and with low temperature near infrared luminescence measurements of InN films deposited by a modified Ion Beam Assisted Deposition technique. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
AlN/AlGaN/GaN buffer optimization on silicon (111): bow and crystal quality control for Si‐CMOS fabs
Authors: Kandaswamy Prem Kumar , Liang Hu , Zhao Ming , Yoga Saripalli , Carlson Eric Porter , Thapa Sarad Bahadur , Hove Marleen Van , Richard Olivier , DeVos Brecht , Vancoille Eric , Dutta Barun 
Published: February 2014

AbstractIn GaN‐on‐silicon there are many challenges which are currently encountered when making this technology compatible with standard Si‐CMOS fabs especially the bow. Bringing this technology to CMOS fabs can potentially drive the costs down, in addition to the cost advantage expected from large wafer sizes. We report here on the impact of AlN nucleation layer on crystal quality and bow. The focus will be on V/III ratios and pre‐dose conditions for AlN, which have considerable effect on the AlN/AlGaN/GaN buffer structures. We will also discuss how AlN thickness can be used to tune the bow. Finally, a brief description on the effect of surface pits will be presented.(© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vacancy defects in UV‐transparent HVPE‐AlN
Authors: Kuittinen Tanja , Tuomisto Filip , Kumagai Yoshinao , Nagashima Toru , Kinoshita Toru , Koukitu Akinori , Collazo Ramón , Sitar Zlatko 
Published: February 2014

AbstractWe used positron annihilation spectroscopy to study bulk AlN single crystals grown by physical vapor transport (PVT) and hydride vapor phase epitaxy (HVPE). Unlike in previous measurements in AlN, we see a clear Alvacancy related lifetime component already at room temperature in HVPE‐AlN. Overall, our results show the more UV‐transparent HVPE‐AlN to have higher concentration of Al‐vacancy related defects than PVT‐AlN, suggesting that Al‐vacancies are not the origin of UV absorption in AlN. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
First‐principles study on the conduction band electron states of GaAsN alloys
Authors: Sakamoto Kei , Yaguchi Hiroyuki 
Published: February 2014

AbstractWe have analyzed the electronic states of the lowest conduction band of GaAsN alloys based on the first‐principles calculation. In order to study the nitrogen concentration dependence of the electron effective mass, we calculated the electronic structure of GaAsN alloys using a full‐potential density functional theory program. The calculated effective mass of GaAsN with a dilute nitrogen concentration is about twice as heavy as that of GaAs. In addition, the effective mass is found to decrease with increasing nitrogen concentration although it is always heavier than that of GaAs. In addition, we calculated the density of states of GaAsN to examine what the cause of the decrease in the effective mass is. Our calculations suggest the discontinuity of the physical property from GaAs to GaAsN and provide an important insight into the formation of the conduction band states of GaAsN alloys. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In situ temperature measurements for selective epitaxy of GaN nanowires
Authors: Bertness Kris A. , Brubaker Matt D. , Harvey Todd E. , Duff Shannon M. , Sanders Aric W. , Sanford Norman A. 
Published: February 2014

AbstractWe demonstrate with spatially resolved, in situ temperature measurements and ex situ reflectance measurements that differences in appearance for masked and unmasked surfaces on patterned growth substrates arise from wavelength‐dependent emissivity variations and not from actual temperature differences. For this study, Si(111) substrates were coated with thin AlN buffer layers (about 40 nm thick) and then further coated with a SiNx mask layer (about 60 nm thick). “Blackbody” emission spectra were collected from homogeneous regions at growth temperatures near those that allow the selective epitaxy of catalyst‐free GaN nanowires on the AlN by molecular beam epitaxy. The data were acquired with a commercial in situ diagnostic system that incorporates optical fiber collection to limit the sampling area to a circle about 5 mm in diameter on the substrate. The emittance spectra are estimated from room‐temperature reflectance measurements. The implication for selectivity mechanisms and temperature measurements in molecular beam epitaxy in general are also discussed. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cross slip of dislocation loops in GaN under shear
Authors: Wu Chi‐Chin , Weingarten N. Scott , Chung Peter W. 
Published: February 2014

AbstractThis work explores possible cross‐slip mechanisms of gliding type <a > = a /3[1 –2 1 0] dislocation loops in wurtzite gallium nitride (GaN) as a function of slip plane. A modified form of the dislocation dynamics code ParaDiS was employed using isotropic linear elasticity and dislocation mobilities estimated in part from molecular dynamics (MD) simulations. Under an externally applied uniform stress, the occurrence of cross slip events is highly dependent on the initial dislocation slip plane. The basal plane is the preferred active plane, owing to the greater mobility of <a > type segments on that plane, over the other planes considered including the prismatic (–1 0 1 0) and two equivalent pyramidal planes (–1 0 1 1) and (1 0 –1 1). For an applied stress state, cross slip processes are more readily seen from the prismatic‐to‐basal planes or the pyramidal‐to‐basal planes, and neither is found to occur in reverse. Cross slip by climb is not presently considered. In all cases, cross‐slip events occur after the loop expands until a greater number of screw‐oriented segments are able to access the cross slip plane and the resolved stresses on the plane become sufficiently large. In comparison to dislocations found in GaN previously, the calculations suggest that some threading dislocations along the [0001] direction that have edge character may have been formed from loops whose screw segments slip and escape on basal planes leaving only the edge segments.
Growth techniques to reduce V‐defect density in GaN and AlGaN layers grown on 200 mm Si (111) substrate
Authors: Liang Hu , Saripalli Yoga , Kandaswamy Prem Kumar , Carlson Eric Porter , Favia Paola , Richard Olivier , Bender Hugo , Zhao Ming , Thapa Sarad Bahadur , Vancoille Eric 
Published: February 2014

AbstractV‐defects can be very detrimental to the functionality of GaN based light emitting diodes (LEDs) and high power transistors grown on 200 mm Si (111) substrates. This work focuses on reducing these detrimental defects in the GaN/AlGaN/AlN stacks grown in a Veeco Turbodisc Maxbright MOCVD system. The origins of V‐defects in GaN/AlGaN/AlN material were studied by cross‐sectional transmission electron microscope (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM). It was found that V‐defects were associated with inversion domain boundary (IDB) like defects, which started from the interface between the AlN nucleation layers and the Si (111) substrates. These IDB‐like defects were terminated by generating V‐defects in the upper layers. Encouraging the 2‐D GaN growth mode helped to close these V‐defects in the GaN layers, but relaxed the built‐in compressive stress faster and resulted in excessive wafer bow. Optimizing the V/III ratio during the AlN nucleation step improved AlN crystal quality and surface morphology, and close V‐defects in GaN without degrading wafers stress condition.
Retention properties with high‐temperature resistance in (Bi,Pr)(Fe,Mn)O3 thin film capacitor
Authors: Nomura Yukihiro , Nomura Keisuke , Kinoshita Koyo , Kawae Takeshi , Morimoto Akiharu 
Published: February 2014

Abstractmagnified image(Bi0.9Pr0.1)(Fe0.97Mn0.03)O3 (BPFM) thin film was deposited on Pt‐coated Si(100) substrate by chemical solution deposition. Remnant polarization and coercive field in the BPFM film capacitor were 113 °C/cm2 and 630 kV/cm at the maximum electric field of 1000 kV/cm, respectively. Switching charge measured by a rectangular pulse measurement was 118 °C/cm2. Almost no polarization losses of BPFM film capacitor were observed even after retention time of 104 s at room temperature. Furthermore, the polarization loss at 450 °C was only 3.7% even after 104 s. These results indicate that BPFM film capacitor is suitable for non‐volatile memory applications at high temperature. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferroelectric properties and switching endurance of Hf0.5Zr0.5O2 films on TiN bottom and TiN or RuO2 top electrodes
Authors: Park Min Hyuk , Kim Han Joon , Kim Yu Jin , Jeon Woojin , Moon Taehwan , Hwang Cheol Seong 
Published: February 2014

Abstractmagnified imageThe effect of the top electrode (TE) on the ferroelectric properties and switching endurance of thin Hf0.5Zr0.5O2 films was examined. The TiN/Hf0.5Zr0.5O2/TiN capacitor can endure electric cycling up to 109 times, which is promising for the next‐generation memory. RuO2 TE was reduced during annealing due to the reactive TiN bottom electrode, resulting in the degradation of the ferroelectric properties and endurance. In addition, the endurance of the TiN/Hf0.5Zr0.5O2/TiN capacitors was optimized by changing the film thickness and the postannealing temperature. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A systematic investigation of the fragmentation pattern of two furanoheliangolide C‐8 stereoisomers using electrospray ionization mass spectrometry
Authors: Sartori Lucas Rossi , Vessecchi Ricardo , Humpf Hans‐Ulrich , Da Costa Fernando Batista , Lopes Norberto Peporine 
Published: February 2014

RATIONALEBudlein A is a sesquiterpene lactone (STL) with some reported biological activities. Pre‐clinical studies to identify in vivo metabolites often employ hyphenated techniques such as liquid chromatography/tandem mass spectrometry (LC/MS/MS). It is also possible to use the fragmentation pattern obtained by Collision‐Induced Dissociation (CID) and Higher Energy Collision‐Induced Dissociation (HCD) to distinguish between the stereoisomers budlein A and centratherin.METHODSThe experiments were carried out in the positive mode using four different spectrometers with an electrospray ionization (ESI) source: (a) Waters ACQUITY® TQD triple quadrupole mass spectrometer (QqQ), (b) AB Sciex API 4000 QTrap® (QqQ), (c) Bruker Daltonics micrOTOF™‐Q II (time‐of‐flight, QTOF), and (d) Thermo Scientific LTQ Orbitrap XL hybrid FTMS (Fourier transform mass spectrometer). Computational chemistry studies helped to identify the protonation sites. The B3LYP/6‐31G(d) model furnished the equilibrium geometries and energies.RESULTSThe stereochemistry (α‐ or β‐orientation) of the centratherin and budlein A side‐chain esters influences the fragmentation pattern recorded on QqQ, QTOF, and Orbitrap‐HCD. On QqQ, centratherin releases the side chain, to generate the m/z 275 fragment ion, whereas budlein A gives the m/z 83 fragment ion. On QTOF and Orbitrap‐HCD, only budlein A affords the m/z 293 and 83 fragment ions, respectively.CONCLUSIONSThe data suggest that proton migration governs the fragmentation pathways under α‐ or β‐orientation. The difference in the QqQ, QTOF, and Orbitrap‐HCD spectral profiles of each isomer can help to distinguish between centratherin and budlein A using MS/MS, which becomes an alternative to nuclear magnetic resonance (NMR) analysis. Copyright © 2014 John Wiley & Sons, Ltd.
Fault estimation observer design for discrete‐time systems in finite‐frequency domain
Authors: Zhang Ke , Jiang Bin , Shi Peng , Xu Jingfa 
Published: February 2014

SummaryThis paper proposes a framework of fault estimation observer design in finite‐frequency domain for discrete‐time systems. First, under the multiconstrained idea, a full‐order fault estimation observer in finite‐frequency domain is designed to achieve fault estimation by using the generalized Kalman–Yakubovich–Popov lemma to reduce conservatism generated by the entire frequency domain. Then, a reduced‐order fault estimation observer is constructed, which results in a new fault estimator to realize fault estimation using current output information. Furthermore, by introducing slack variables, improved results on full‐order fault estimation observer and reduced‐order fault estimation observer design with finite‐frequency specifications are obtained such that different Lyapunov matrices can be separately designed for each constraint. Simulation results are presented to illustrate the advantages of the theoretic results obtained. Copyright © 2014 John Wiley & Sons, Ltd.
Running Rescues Defective Adult Neurogenesis by Shortening the Length of the Cell Cycle of Neural Stem and Progenitor Cells
Authors: Farioli-Vecchioli Stefano , Mattera Andrea , Micheli Laura , Ceccarelli Manuela , Leonardi Luca , Saraulli Daniele , Costanzi Marco , Cestari Vincenzo , Rouault Jean-Pierre , Tirone Felice 
Published: February 2014

Abstract
Physical exercise increases the generation of new neurons in adult neurogenesis. However, only few studies have investigated the beneficial effects of physical exercise in paradigms of impaired neurogenesis. Here, we demonstrate that running fully reverses the deficient adult neurogenesis within the hippocampus and subventricular zone of the lateral ventricle, observed in mice lacking the antiproliferative gene Btg1. We also evaluated for the first time how running influences the cell cycle kinetics of stem and precursor subpopulations of wild-type and Btg1-null mice, using a new method to determine the cell cycle length. Our data show that in wild-type mice running leads to a cell cycle shortening only of NeuroD1-positive progenitor cells. In contrast, in Btg1-null mice, physical exercise fully reactivates the defective hippocampal neurogenesis, by shortening the S-phase length and the overall cell cycle duration of both neural stem (glial fibrillary acidic protein+ and Sox2+) and progenitor (NeuroD1+) cells. These events are sufficient and necessary to reactivate the hyperproliferation observed in Btg1-null early-postnatal mice and to expand the pool of adult neural stem and progenitor cells. Such a sustained increase of cell proliferation in Btg1-null mice after running provides a long-lasting increment of proliferation, differentiation, and production of newborn neurons, which rescues the impaired pattern separation previously identified in Btg1-null mice. This study shows that running positively affects the cell cycle kinetics of specific subpopulations of newly generated neurons and suggests that the plasticity of neural stem cells without cell cycle inhibitory control is reactivated by running, with implications for the long-term modulation of neurogenesis. Stem Cells 2014;32:1968–1982
Crown–rump length discordance and adverse perinatal outcome in twin pregnancies: systematic review and meta‐analysis
Authors: D'Antonio F. , Khalil A. , Pagani G. , Papageorghiou A. T. , Bhide A. , Thilaganathan B. 
Published: February 2014

ABSTRACTObjectiveThe aim of this systematic review was to explore the relationship between crown–rump length (CRL) discordance detected at 11–14 weeks of gestation and adverse outcome in twin pregnancy and to assess its predictive accuracy.MethodsA protocol designed a priori following MOOSE guidelines and recommended for systematic review and meta‐analysis was used. The outcomes observed were: total fetal and perinatal loss, fetal loss at < 24 weeks, fetal loss at ≥ 24 weeks, birth‐weight (BW) discordance, preterm delivery (PTD) at < 34 weeks and fetal anomalies. The analysis was performed for all twins and for dichorionic (DC) and monochorionic (MC) twins separately.ResultsA total of 2008 articles were identified and 17 studies were included in the systematic review. Twin pregnancies with CRL discordance ≥ 10% were at significantly higher risk of perinatal loss (RR, 2.80; 95% CI, 1.25−6.27; P = 0.012), fetal loss at ≥ 24 weeks (RR, 4.07; 95% CI, 1.47−11.23; P = 0.006), BW discordance (RR, 2.24; 95% CI, 1.89–2.64; P < 0.001) and PTD at < 34 weeks (RR, 1.49; 95% CI, 1.23−1.80; P < 0.001) but not of fetal loss at < 24 weeks (P = 0.130). A meta‐analysis of fetal anomalies was not possible because fewer than two studies explored this outcome. However, when used alone to screen for adverse pregnancy outcome, the predictive accuracy of CRL discordance was low for each of the outcomes explored.ConclusionCRL discordance is associated with an increased risk of adverse pregnancy outcome. However, the accuracy of CRL discordance in predicting adverse outcome is poor and thus limits its routine use in clinical practice. Copyright © 2014 ISUOG. Published by John Wiley & Sons Ltd
Communicating adaptation to climate change: the art and science of public engagement when climate change comes home
Authors: Moser Susanne C. 
Published: February 2014

This article synthesizes relevant literature and examples from practice to examine what is known to date about communicating climate change adaptation. It explores the language used to discuss adaptation, what is known about resonant frames, drawing on adaptation discourses in policy, practice, and the media. Identifying trends and widely applicable insights is made challenging not only by the variety of words used to speak of adaptation, but by the fact that ‘adaptation’ language is often not used at all. A broad literature on perceptions and experiences of climate change impacts and how these experiences affect people's valuations and emotional responses to climate change offers crucial insights to the challenges and opportunities in communicating adaptation. It reveals much about people's interest in and acceptability and knowledge of adaptation, about preferred timing and who is thought to be responsible for enacting adaptive actions. Insights from the literature on place attachment and place identity are of particular relevance to public engagement on adaptation as it goes a long way toward explaining the quality of the adaptation debate to date while offering promising opportunities for dialogue. Suggestions for improved adaptation communication practice and critical research gaps are offered.This article is categorized under:

Perceptions, Behavior, and Communication of Climate Change > Communication
Vulnerability and Adaptation to Climate Change > Institutions for Adaptation
Models of language evolution and change
Authors: Smith Andrew D.M. 
Published: February 2014

AbstractIn the absence of direct evidence of the emergence of language, the explicitness of formal models which allow the exploration of interactions between multiple complex adaptive systems has proven to be an important tool. Computational simulations have been at the heart of the field of evolutionary linguistics for the past two decades, particularly through the language game and iterated learning paradigms, but these are now being extended and complemented in a number of directions, through formal mathematical models, language‐ready robotic agents, and experimental simulations in the laboratory.This article is categorized under:Linguistics > Computational Models of LanguageLinguistics > Evolution of Language
Applied statistics for extreme wind estimate
Authors: Castellani Francesco , Garinei Alberto , Terzi Ludovico , Astolfi Davide 
Published: February 2014

AbstractThe assessment of extreme wind speeds is a crucial issue for securing structural safety of wind turbines and inquiring largest loads to which turbines must be prepared to undergo.International standards suggest applying the Gumbel method of fitting the annual maxima to their theoretic probability distribution. Yet, often, wind databases are too short to apply such methods with statistical significance, and other procedures are commonly adopted [such as peaks over threshold (POT) and independent storms], which involve dependency on arbitrary thresholds for filtering data and issues of sub‐asymptocity, i.e. how well the selected dataset fits to density functions describing the distribution of peaks or extreme values.The present paper aims at contributing to such currently ongoing debate, providing a statistical analysis of the application of POT and independent storms methods on wind time series of various lengths from different geographical areas.The CERN data analysis framework ROOT has been employed for guaranteeing excellent standards of computational precision and wealth of statistical information. Analysis of uncertainties in the wind speeds estimates and tests of the goodness of fit of the datasets to the proper distributions have been carried on. An algorithm for choosing the optimum thresholds was developed, which encapsules and compromises the statistical complexity of the methods. A declustering procedure has been carried on for discriminating proper peaks in the POT method: it has been tested that such declustering provides a dramatic improvement of the statistical quality of the method. Copyright © 2014 John Wiley & Sons, Ltd.