bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural, chemical, and electrical characterization of indium nitride produced by pulsed laser ablation
Authors: Orlando Stefano , Santagata Antonio , Parisi Giovanni Pompeo , Medici Luca , Kaciulis Saulius , Mezzi Alessio , Bellucci Alessandro , Cappelli Emilia , Trucchi Daniele Maria 
Published: January 2012

AbstractThe peculiar electronic characteristics of indium nitride offers great technological potential for novel device applications in several areas such as: multi‐junction solar cells, terahertz emitters, chemical sensors, and light emitting diodes. Reactive pulsed laser ablation has been used to deposit indium nitride thin films for its versatility. The laser source employed has been a Nd:YAG (∼8 ns, 532 nm, 10 Hz) performing the ablation in a RF‐generated nitrogen plasma. Thin films have been deposited varying some parameters such as the substrate temperature, the nitrogen gas pressure, and the RF power. Structural (XRD) and chemical (XPS) characterizations have been performed. Electrical resistivity of the films has been evaluated to correlate structural and chemical properties to the electrical ones. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low loss EEL spectroscopy performed on InxAl1‐xN layers grown by MOVPE: comparison between experiment and ab‐initio calculations
Authors: Letrouit A. , Kret S. , Ivaldi F. , Carlin J. F. , Kaufman N. A. K. , Grandjean N. , Górecka J. 
Published: January 2012

AbstractWe present Electron Energy‐Loss Spectroscopy (EELS) studies of InxAl1‐xN MOVPE epilayers containing 16‐28 at% of indium. EELS investigations show a significant change of the plasmon energy (Ep) with the indium concentration. In the case of these compounds, the results have been compared for the first time with ab‐initio calculations performed with Wien2k and present a good agreement. Ep follows a linear relation with respect to composition allowing the correct identification of the spectra features. The acquisitions of the low‐loss EELS spectra have been performed in the homogeneous area for all the InxAl1‐xN samples. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
InGaN/GaN quantum wells grown on freestanding HfO2 photonic crystals
Authors: Wang Yongjin , Wu Tong , Hu Fangren , Zhu Hongbo , Hane Kazuhiro 
Published: January 2012

AbstractWe report here epitaxial growth of InGaN/GaN quantum wells (QWs) on suspended HfO2 photonic crystal structures by molecular beam epitaxy (MBE). Suspended HfO2 photonic crystals are achieved on silicon substrate by combining film evaporation, electron beam lithography, fast atom beam etching of HfO2 film with dry etching of silicon substrate. InGaN/GaN QWs are subsequently grown on suspended HfO2 photonic crystal structures by MBE technique, and freestanding HfO2 photonic crystal slab can sustain complicated stress change during MBE growth. The reflectance and photoluminescence measurements are performed for epitaxial III‐nitride structures (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical studies of GaN nanocolumns containing InGaN quantum disks and the effect of strain relaxation on the carrier distribution
Authors: Holmes Mark J. , Park Young S. , Wang Xu , Chan Christopher C. S. , Reid Benjamin P. L. , Kim HeeDae , Luo Jun , Warner Jamie H. , Taylor Robert A. 
Published: January 2012

AbstractThe optical properties of GaN nanocolumns containing pairs of InxGa1–xN (x ∼ 0.1) quantum disks (QDisks) have been experimentally measured. Strain simulations reveal an inhomogeneous distribution of strain, and furthermore, a relaxation between successive QDisks along the growth direction of the column. Although this inhomogeneous distribution of strain may indicate a lateral separation of carriers in the QDisk, the decay lifetime of the emission suggests far less carrier separation. The quantum confined stark effect is found to create an inhomogeneous distribution of charge within the QDisks along the growth direction of the rod. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of hole injection in AlGaN/GaN HEMT with GIT structure by numerical simulation
Authors: Chonan Hiroshi , Ide Toshihide , Shen Xu‐Qiang , Shimizu Mitsuaki 
Published: January 2012

AbstractThe numerical simulation of the AlGaN/GaN HEMT with GIT structure is performed while varying the radiative recombination lifetime of electron and hole, and the conductivity modulation in the channel by the hole injection from the gate electrode is investigated. When the radiative recombination lifetime is long, two peaks in the transconductance curve, gm vs. VG is found, and the hole injection from the gate electrode is enhanced. The accumulation of hole is found in the GaN layer under the channel around the source electrode, and the conductivity modulation is significant at the source‐gate region and at the drain side of the gate electrode. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of peak electric field strength in GaN‐HEMT with carbon doping layer
Authors: Narita Tetsuo , Kikuta Daigo , Iguchi Hiroko , Ito Kenji , Tomita Kazuyoshi , Uesugi Tsutomu , Kachi Tetsu 
Published: January 2012

AbstractWe propose a reduction in the peak electric field strength at the drain side of the gate electrode in a high‐electron mobility transistor using a carbon‐doped GaN layer. Simulation results indicated that the peak electric field strength decreased with decrease in the spacing between the 2‐dimensional electron gas (2DEG) channel and the carbon doped GaN layer due to the acceptor‐like states of carbon. Experimental results supported the simulation results by the higher breakdown voltages obtained with smaller spacing layers. Current collapse phenomena were relatively suppressed with a 0.5 µm thick spacing layer compared to 2 or 3 µm thick spacing layers, due to reduction of the electric field strength. From these results, we could conclude that the carbon doped GaN layer enables the combination of high breakdown voltage and low current collapse by improved design of the spacing between the channel and the carbon containing layer in a GaN‐based device (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Faceting in AlN bulk crystal growth and its impact on optical properties of the crystals
Authors: Bickermann Matthias , Epelbaum Boris M. , Filip Octavian , Tautz Barbara , Heimann Paul , Winnacker Albrecht 
Published: January 2012

AbstractThe surface of bulk AlN single crystals grown by PVT on Al‐polar (0001) seeds is typically constructed from prismatic, pyramidal, and basal plane facets. Simultaneous growth on different facets with different surface kinetics leads to formation of a zonar structure which is visible due to local differences in coloration in the wafers. Four zones on an AlN wafer representing (1) growth on {1013} pyramidal facets, (2) growth adjacent to ridges and (0001) basal plane facets, and (3) + (4) outer and centre areas corresponding to surface depressions are investigated. They show striking differences in optical absorption (OA) spectra, cathodoluminescence (CL) spectra and chemical analysis (SIMS). In areas near ridges and (0001) facets and in centres of depressions, deep‐UV absorption as well as luminescence is significantly increased. We assign OA and CL bands observed in these zones to the presence of carbon and/or the lack of oxygen due to local segregation effects caused by faceting. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Higher output power of near‐ultraviolet LED grown on GaN substrate with back‐side etching
Authors: Fang Yen‐Hsiang , Fu Yi‐Keng , Xuan Rong , Jiang Ren‐Hao , Lin Chia‐Feng 
Published: January 2012

AbstractThe 405 nm near‐ultra violet (NUV) InGaN/GaN multiple‐quantum‐well light‐emitting diodes (LEDs) grown on GaN substrate with a roughened backside on the N‐face surface of GaN substrate were fabricated through a chemical wet‐etching process to increase light‐extraction efficiency. The stable crystallographic etching planes were formed as the GaN {1011} planes. The back‐side etching NUV LEDs had larger output power than that of conventional NUV‐LEDs, NUV‐LEDs with wider wells, and NUV‐LEDs grown on pattern sapphire substrate.When the NUV LED were operated as a forward current of 20 mA, the increasing output power of back‐side etching NUV LEDs was about 70%, 106%, and 8% than that of conventional NUV‐LEDs, NUV‐LEDs with wider wells, and NUV‐LEDs grown on pattern sapphire substrate (PSS), respectively. This larger enhancement result from the improved light extraction attributed to the different transmittance as hexagonal pyramid on N‐face GaN was etched (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Valence band offsets at oxide/InN interfaces determined by X‐ray photoelectron spectroscopy
Authors: Eisenhardt Anja , Eichapfel Georg , Himmerlich Marcel , Knübel Andreas , Passow Thorsten , Wang Chunyu , Benkhelifa Fouad , Aidam Rolf , Krischok Stefan 
Published: January 2012

AbstractThe valence band offset (VBO) at the interface between indium nitride (InN) and selected oxide materials (Al2O3, TiO2, In2O3 and HfO2) is determined using X‐ray photoelectron spectroscopy (XPS). For exact VBO determination, InN samples with oxide cap layers of varying thickness are investigated. The VBO values are extrapolated by linear regression of the thickness dependent energetic distances ΔE between the valence band maxima (VBM) at the oxide and InN surface and their corresponding heterointerface. The determined VBO values are (2.7 ± 0.2) eV for Al2O3/InN, (1.8 ± 0.2) eV for TiO2/InN, (1.5 ± 0.2) eV for In2O3/InN, (1.3 ± 0.2) eV for e‐beam evaporated HfO2 on InN, and (2.0 ± 0.2) eV for atomic layer deposited HfO2 on InN. In some cases the oxide deposition process leads to an oxidation of the InN film at the oxide/InN interface (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Responsivity and photocurrent dynamics in single GaN nanowires
Authors: González‐Posada F. , Songmuang R. , Den Hertog M. , Monroy E. 
Published: January 2012

AbstractWe report on the photocurrent behaviour of single GaN n+‐n ‐n+ nanowires (NWs) grown by plasma‐assisted molecular‐beam epitaxy on Si(111). The ultraviolet (350 nm) to visible (450 nm) responsivity ratio is larger than three orders of magnitude. A relevant feature is that the photocurrent scales sublinearly with optical power, following a I ∼ Pα (α < 1) law in all the measured range, with α increasing with the measuring frequency. The photocurrent time response remains in the tens/hundreds of millisecond range, in contrast to the persistent (hours) photoconductivity effects observed in two‐dimensional photoconductors. The NW performance is independent of the measuring atmosphere, either in the air or in vacuum. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Integrated high reflectivity silicon substrates for GaN LEDs
Authors: Arkun F. Erdem , Dargis Rytis , Smith Robin , Williams David , Clark Andrew , Lebby Michael 
Published: January 2012

AbstractGrowth of GaN on epitaxial distributed Bragg reflectors (DBR) capable of 80% reflectivity at typical III‐N based LED operating wavelengths is presented. Such structures are formed by growing single crystal multilayers of gadolinium oxide‐silicon stacks on silicon (111) substrates. The large refractive index difference between gadolinium oxide and silicon (Δn = 2.2) allows highly reflective DBR mirrors to be achieved at as little as three periods. Growth of GaN is demonstrated on the DBR mirrors making these structures suitable for GaN based LED growth. DBR mirrors embedded in this engineered substrate act as a reflecting mirror for incident light from a LED grown on top of this substrate. This potentially allows increased light extraction and higher output power from these LEDs compared to that of similar LEDs grown on silicon substrates. Performance of DBR mirrors with GaN top layers as a function of the incident angle of a 488 nm laser is investigated. X‐ray diffraction and TEM are used for structural characterization of these grown structures. This engineered substrate, Mirrored SiliconTM, is suitable for high volume manufacturing at 150 and 200 mm wafers sizes. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A contextual theory of organizational learning from failures and successes: A study of acquisition completion in the global newspaper industry, 1981–2008
Authors: Muehlfeld Katrin , Rao Sahib Padma , Van Witteloostuijn Arjen 
Published: January 2012

AbstractThis study develops and tests theory about the context‐specificity and outcome‐dependence of experiential learning in acquisition processes. First, we investigate whether learning from experience gained in different acquisition contexts is limited to influencing subsequent outcomes of same‐context transactions. Second, we analyze whether learning patterns in response to prior successes and failures differ across acquisition contexts, depending on two properties of these contexts—the degree of structural variance and the level of stimulation of deliberate learning. Learning is assessed with respect to an underexplored organizational goal variable in acquisitions: completion of a publicly announced transaction. An analysis of 4,973 acquisition attempts in the newspaper industry in 1981–2008 largely supports our theory. Copyright © 2012 John Wiley & Sons, Ltd.
Multiscale models of thrombogenesis
Authors: Xu Zhiliang , Kim Oleg , Kamocka Malgorzata , Rosen Elliot D. , Alber Mark 
Published: January 2012

AbstractTo restrict the loss of blood follow from the rupture of blood vessels, the human body rapidly forms a clot consisting of platelets and fibrin. However, to prevent pathological clotting within vessels as a result of vessel damage, the response must be regulated. Clots forming within vessels (thrombi) can restrict the flow of blood causing damage to tissues in the flow field. Additionally, fragments dissociating from the primary thrombus (emboli) may lodge and clog vessels in the brain (causing ischemic stroke) or lungs (resulting in pulmonary embolism). Pathologies related to the obstruction of blood flow through the vasculature are the major cause of mortality in the United States. Venous thromboembolic disease alone accounts for 900,000 hospitalizations and 300,000 deaths per year and the incidence will increase as the population ages (Wakefield et al. J Vasc Surg 2009, 49:1620–1623). Thus, understanding the interplay between the many processes involved in thrombus development is of significant biomedical value. In this article, we first review computational models of important subprocesses of hemostasis/thrombosis including coagulation reactions, platelet activation, and fibrin assembly, respectively. We then describe several multiscale models integrating these subprocesses to simulate temporal and spatial development of thrombi. The development of validated computational models and predictive simulations will enable one to explore how the variation of multiple hemostatic factors affects thrombotic risk providing an important new tool for thrombosis research. WIREs Syst Biol Med 2012 doi: 10.1002/wsbm.1160This article is categorized under:

Models of Systems Properties and Processes > Cellular Models
Developmental Biology > Developmental Processes in Health and Disease
Physiology > Mammalian Physiology in Health and Disease
Biological Mechanisms > Regulatory Biology
Changing Strategies for Child Welfare, Enduring Beliefs about Childhood: The Fresh Air Fund, 1877–1926
Authors: Guarneri Julia 
Published: January 2012

In 1877, a Congregational pastor started a modest effort to send New York City tenement children on two-week summer vacations in country homes. The pastor's Fresh Air Fund grew, in the following decades, into a hugely popular program and a celebrated cause. The charity thrived in part because its simple project adapted well to several different reform environments. The fund made a place for itself in the evangelical child-saving efforts of the Gilded Age, the civic-minded reforms of the Progressive Era, and the more individualistic pursuits of the 1920s. In each era, fund leaders cast country vacations as simple means to address middle-class New Yorkers' fears about their changing city, from the influx of immigrants to the spread of disease to rising class tensions.Tracking the Fresh Air Fund over fifty years reveals the sea changes in child-welfare work between 1877 and 1927, but it also calls attention to continuities often overlooked in the history of child welfare. Throughout the Gilded Age and Progressive Era, the fund tapped supporters' constant and deep-seated beliefs in children's potential, the restorative power of the outdoors, and a child's right to play.
In situ proteo-metabolomics reveals metabolite secretion by the acid mine drainage bio-indicator, Euglena mutabilis
Authors: Halter David , Goulhen-Chollet Florence , Gallien Sébastien , Casiot Corinne , Hamelin Jérôme , Gilard Françoise , Heintz Dimitri , Schaeffer Christine , Carapito Christine , Van Dorsselaer Alain , Tcherkez Guillaume , Arsène-Ploetze Florence , Bertin Philippe N 
Published: January 2012

Abstract
Euglena mutabilis is a photosynthetic protist found in acidic aquatic environments such as peat bogs, volcanic lakes and acid mine drainages (AMDs). Through its photosynthetic metabolism, this protist is supposed to have an important role in primary production in such oligotrophic ecosystems. Nevertheless, the exact contribution of E. mutabilis in organic matter synthesis remains unclear and no evidence of metabolite secretion by this protist has been established so far. Here we combined in situ proteo-metabolomic approaches to determine the nature of the metabolites accumulated by this protist or potentially secreted into an AMD. Our results revealed that the secreted metabolites are represented by a large number of amino acids, polyamine compounds, urea and some sugars but no fatty acids, suggesting a selective organic matter contribution in this ecosystem. Such a production may have a crucial impact on the bacterial community present on the study site, as it has been suggested previously that prokaryotes transport and recycle in situ most of the metabolites secreted by E. mutabilis. Consequently, this protist may have an indirect but important role in AMD ecosystems but also in other ecological niches often described as nitrogen-limited.
Identification of a novel cyanobacterial group as active diazotrophs in a coastal microbial mat using NanoSIMS analysis
Authors: Woebken Dagmar , Burow Luke C , Prufert-Bebout Leslie , Bebout Brad M , Hoehler Tori M , Pett-Ridge Jennifer , Spormann Alfred M , Weber Peter K , Singer Steven W 
Published: January 2012

Abstract
N2 fixation is a key process in photosynthetic microbial mats to support the nitrogen demands associated with primary production. Despite its importance, groups that actively fix N2 and contribute to the input of organic N in these ecosystems still remain largely unclear. To investigate the active diazotrophic community in microbial mats from the Elkhorn Slough estuary, Monterey Bay, CA, USA, we conducted an extensive combined approach, including biogeochemical, molecular and high-resolution secondary ion mass spectrometry (NanoSIMS) analyses. Detailed analysis of dinitrogenase reductase (nifH) transcript clone libraries from mat samples that fixed N2 at night indicated that cyanobacterial nifH transcripts were abundant and formed a novel monophyletic lineage. Independent NanoSIMS analysis of 15N2-incubated samples revealed significant incorporation of 15N into small, non-heterocystous cyanobacterial filaments. Mat-derived enrichment cultures yielded a unicyanobacterial culture with similar filaments (named Elkhorn Slough Filamentous Cyanobacterium-1 (ESFC-1)) that contained nifH gene sequences grouping with the novel cyanobacterial lineage identified in the transcript clone libraries, displaying up to 100% amino-acid sequence identity. The 16S rRNA gene sequence recovered from this enrichment allowed for the identification of related sequences from Elkhorn Slough mats and revealed great sequence diversity in this cluster. Furthermore, by combining 15N2 tracer experiments, fluorescence in situ hybridization and NanoSIMS, in situ N2 fixation activity by the novel ESFC-1 group was demonstrated, suggesting that this group may be the most active cyanobacterial diazotroph in the Elkhorn Slough mat. Pyrotag sequences affiliated with ESFC-1 were recovered from mat samples throughout 2009, demonstrating the prevalence of this group. This work illustrates that combining standard and single-cell analyses can link phylogeny and function to identify previously unknown key functional groups in complex ecosystems.
Pseudomonas syringae naturally lacking the canonical type III secretion system are ubiquitous in nonagricultural habitats, are phylogenetically diverse and can be pathogenic
Authors: Diallo Moudjahidou Demba , Monteil Caroline L , Vinatzer Boris A , Clarke Christopher R , Glaux Catherine , Guilbaud Caroline , Desbiez Cécile , Morris Cindy E 
Published: January 2012

Abstract
The type III secretion system (T3SS) is an important virulence factor of pathogenic bacteria, but the natural occurrence of variants of bacterial plant pathogens with deficiencies in their T3SS raises questions about the significance of the T3SS for fitness. Previous work on T3SS-deficient plant pathogenic bacteria has focused on strains from plants or plant debris. Here we have characterized T3SS-deficient strains of Pseudomonas syringae from plant and nonplant substrates in pristine nonagricultural contexts, many of which represent recently described clades not yet found associated with crop plants. Strains incapable of inducing a hypersensitive reaction (HR−) in tobacco were detected in 65% of 126 samples from headwaters of rivers (mountain creeks and lakes), snowpack, epilithic biofilms, wild plants and leaf litter and constituted 2 to 100% of the P. syringae population associated with each sample. All HR− strains lacked at least one gene in the canonical hrp/hrc locus or the associated conserved effector locus, but most lacked all six of the genes tested (hrcC, hrpL, hrpK1, avrE1 and hrpW1) and represented several disparate phylogenetic clades. Although most HR− strains were incapable of causing symptoms on cantaloupe seedlings as expected, strains in the recently described TA-002 clade caused severe symptoms in spite of the absence of any of the six conserved genes of the canonical T3SS according to PCR and Southern blot assays. The phylogenetic context of the T3SS variants we observed provides insight into the evolutionary history of P. syringae as a pathogen and as an environmental saprophyte.
Proteus mirabilis interkingdom swarming signals attract blow flies
Authors: Ma Qun , Fonseca Alicia , Liu Wenqi , Fields Andrew T , Pimsler Meaghan L , Spindola Aline F , Tarone Aaron M , Crippen Tawni L , Tomberlin Jeffery K , Wood Thomas K 
Published: January 2012

Abstract
Flies transport specific bacteria with their larvae that provide a wider range of nutrients for those bacteria. Our hypothesis was that this symbiotic interaction may depend on interkingdom signaling. We obtained Proteus mirabilis from the salivary glands of the blow fly Lucilia sericata; this strain swarmed significantly and produced a strong odor that attracts blow flies. To identify the putative interkingdom signals for the bacterium and flies, we reasoned that as swarming is used by this bacterium to cover the food resource and requires bacterial signaling, the same bacterial signals used for swarming may be used to communicate with blow flies. Using transposon mutagenesis, we identified six novel genes for swarming (ureR, fis, hybG, zapB, fadE and PROSTU_03490), then, confirming our hypothesis, we discovered that fly attractants, lactic acid, phenol, NaOH, KOH and ammonia, restore swarming for cells with the swarming mutations. Hence, compounds produced by the bacterium that attract flies also are utilized for swarming. In addition, bacteria with the swarming mutation rfaL attracted fewer blow flies and reduced the number of eggs laid by the flies. Therefore, we have identified several interkingdom signals between P. mirabilis and blow flies.