32,108 research outputs found
Ab Initio Study of Octane Moiety Adsorption on H- and Cl-Functionalized Silicon Nanowires
No full textUsing first-principles calculations based on density functional theory, we investigated the effects of surface functionalization on the energetic and electronic properties of hydrogenated and chlorinated silicon nanowires oriented along the <112> direction. We show that the band structure is strongly influenced by the diameter of the nanowire, while substantial variations in the formation energy are observed by changing the passivation species. We modeled an octane moiety absorption on the (111) and (110) surface of the silicon nanowire to address the effects on the electronic structure of the chlorinated and hydrogenated systems. We found that the moiety does not substantially affect the electronic properties of the investigated systems. Indeed, the states localized on the molecules are embedded into the valence and conduction bands, with no generation of intragap energy levels and moderated change in the band gap. Therefore, Si-C bonds can enhance protection of the hydrogenated and chlorinated nanowire surfaces against oxidation without substantial modification of the electronic properties. However, we calculated a significant charge transfer from the silicon nanowires to the octane moiety
Enhancing the electronic properties of VLS-grown silicon nanowires by surface charge transfer
No full textThe need to develop new energy storage technology has led to deeper investigation into materials science to produce highly efficient batteries, primarily the lithium ion battery. The importance of electrodes in such devices has led to the reemergence of silicon nanowires (Si NWs) at the forefront of materials study—in this context, as an energy storage material (as electrodes). Redox potential and work function play the most important roles in charge transfer, the battery charging/discharging process. Thus, the NWs’ interfacial properties become important in achieving higher stability and efficiency. In this work, a deep study was conducted using equilibrium perturbation to change the surface electronic properties of Si NWs, which can be integrated into various technologies, while simultaneously achieving an interesting interface that is chemically passive and cheap to produce. By using an X-ray photoelectron spectroscope, a Kelvin probe, and contact angle measurement, combined with theoretical analysis, a full picture is achieved regarding the Si NWs’ interface, paving the way for this new technique to develop unique interfaces and to achieve a higher energy capacity and a longer lifetime
Uniform Tendency of Surface Dipoles Across Silicon Doping Levels and Types of H-Terminated Surfaces
No full textThe termination of surface-dangling bonds on silicon through hydrogen atoms, also known as Si–H, can achieve chemical passivation and reduce surface states in the electronic bandgap, thus altering electronic properties. Through a comprehensive study of doping levels (1014–1020 cm−3) and types (n and p), a consistent surface dipole trend induced by Si–H termination is discovered. It is achieved by redistributing surface charges and establishing thermal equilibrium with the chemical bond. To resolve this, the surface work function, surface electron affinity, and the energy difference between the valence band and the Fermi level are measured by employing the Kelvin probe, X-ray photoelectron spectroscopy, and photoelectron yield spectroscopy methods. These findings are further validated through ab initio simulations. This finding has immense implications not only for eliminating electronic defects at semiconductor interfaces, which is crucial in microelectronics but also for developing and engineering hybrid interfaces and heterojunctions with controlled electronic properties
Landsat MSS classification of fire fuel types in Wood Buffalo National Park, northern Canada
No full textJ1: Global Ecology & Biogeography Letters; M3: Article; Milne, David Franklin, Steven E. Wilson, Bradley A. Ghitter, Geoff Heathcott, Mark McCaffrey, Thomas M. Ow, Charlotte F. Y.; Source Information: Mar1994, Vol. 4 Issue 2, p33; Subject Term: FOREST fires; Author-Supplied Keyword: Canada (Wood Buffalo National Park); Author-Supplied Keyword: Forest fire; Author-Supplied Keyword: Fuel type classification; Author-Supplied Keyword: Landsat data; Number of Pages: 0p; Document Type: Articl
The long-wavelength view of GG Tau A: rocks in the ring world
No full textWe present the first detection of GG Tau A at centimetre wavelengths, made with the Arcminute Microkelvin Imager Large Array at a frequency of 16 GHz (λ = 1.8 cm). The source is detected at >6 σrms with an integrated flux density of S16GHz = 249 ± 45 µJy. We use these new centimetre-wave data, in conjunction with additional measurements compiled from the literature, to investigate the long-wavelength tail of the dust emission from this unusual protoplanetary system. We use an MCMC-based method to determine maximum likelihood parameters for a simple parametric spectral model and consider the opacity and mass of the dust contributing to the microwave emission. We derive a dust mass of Md ~ 0.1 Msun, constrain the dimensions of the emitting region and find that the opacity index at λ > 7 mm is less than unity, implying a contribution to the dust population from grains exceeding ~4 cm in size. We suggest that this indicates coagulation within the GG Tau A system has proceeded to the point where dust grains have grown to the size of small rocks with dimensions of a few centimetres. Considering the relatively young age of the GG Tau association in combination with the low derived disc mass, we suggest that this system may provide a useful test case for rapid core accretion planet formation models
Letter from Cedrick M. Shimo to the Office of Redress Administration, June 4, 1991
No full textA letter from Cedrick M. Shimo to the Office of Redress Administration arguing that John Y. Udaka is entitled to a redress payment.These materials are from box 73 and 74 of the Frank Chin Papers. The Frank Chin Papers contain personal and professional correspondence between Frank Chin and Michi Weglyn relating to particular projects on which either author was working as well as files related to the Day of Remembrance Tribute to Michi Weglyn
Los jesuitas expulsos literatos en la Italia del Setecientos : éxitos y fracasos
No full textLa historiografía ha definido a los jesuitas españoles expulsos como "mediatores" entre dos culturas: durante el largo exilio italiano (1767-1815) ellos, gracias a la habilidad sincrética propia de la Compañía de Jesús, llegaron a producir una "cultura hispano italiana", según la célebre definición de M. Batllori. El propósito de mi intervención es ofrecer unas breves reflexiones sobre unas figuras de ex-jesuitas epañoles "literatos", particularmente Juan Andrés y Esteban Arteaga. Aunque varios expulsos alcanzaron un buen éxito literario, la mayoría de ellos experimentó los sinsabores, las miserias y las dificultades económicas propias del amplio sector de la intelectualidad que intentó emerger en el difícil escenario de la República literaria europea del siglo XVIII, un sector que el gran especialista en la Ilustración francesa Robert Darnton ha definido como Grub street.Expelled Spanish jesuits have been regarded by current Historiography as "cultural mediators": during their long exile in Italy (1767-1815), they developed a "Spanish Italian culture" (according to M. Batllori's definition) thanks to a meaningful syncretic approach. The author offers some brief reflections on those expelled jesuits who decided to porsue a litterary career, with a specific focus on Juan Andrés and Esteban Arteaga. Through several spanish fathers achieved a good literary success, the majority of them suffered the typical failures, delusions and troubles experienced by eighteenth century men of letters, especially those who belonged to a sector of the Republic of Letters called by Robert Darnton "Grub Street"
Nonstrangulating small colon obstruction caused by a submucosal haematoma
No full textS. Stahel, C. B. Riley, M. Wichtel and P.-Y. Daous
Overview of the Author Profiling Task at PAN 2013
No full text[EN] This overview presents the framework and results for the Author Profiling
task at PAN 2013. We describe in detail the corpus and its characteristics,
and the evaluation framework we used to measure the participants performance to
solve the problem of identifying age and gender from anonymous texts. Finally,
the approaches of the 21 participants and their results are described.The author profiling task @PAN-2013 was an activity of the WIQ-EI IRSES project (Grant No. 269180) within the FP 7 Marie Curie People Framework of the European Commission. We want to thank the Forensic Lab of the Universitat Pompeu Fabra Barcelona for sponsoring the award for the winner team. The work of the first author was partially funded by Autoritas Consulting SA and by Ministerio de Economía y Competitividad de España under grant ECOPORTUNITY IPT-2012-1220-430000. The work of the second author was in the framework the DIANA-APPLICATIONS-Finding Hidden Knowledge in Texts: Applications (TIN2012-38603-C02-01) project, and the VLC/CAMPUS Microcluster on Multimodal Interaction in Intelligent Systems. The work of fifth author was funded in part by the Swiss National Science Foundation (SNF) project "Mining Conversational Content for Topic Modelling and Author Identification (ChatMiner)" under grant number 200021_130208.Rangel, F.; Rosso, P.; Koppel, M.; Stamatatos, E.; Inches, G. (2013). Overview of the Author Profiling Task at PAN 2013. CLEF Conference on Multilingual and Multimodal Information Access Evaluation. 352-365. https://riunet.upv.es/handle/10251/46636S35236
CONTRIBUTION TO THE STUDY OF PARTIAL DIFFERENTIAL EQUATIONS OF ELLIPTIC TYPE
No full textEn este artículo se presentan los resultados más importantes de mi trabajo de investigación en el estudio de la existencia y de las propiedades de las soluciones de ecuaciones diferenciales parciales no lineales.
Donde λ ∈ R, Ω es un dominio acotado en RN con frontera suave, ∆ = n i=0 ∂/∂x2 i es el operador de Laplace y f : R → R es una función no lineal. Se presentan teoremas obtenidos utilizando teoría de bifurcación, métodos variacionales y un principio de minimax desarrollado por el autor en colaboración con A. Castro y J. M. Neuberger ([Cas-Cos-Nu1], 1997). Además, se incluyen algunos algoritmos para construir y visualizar soluciones a problemas no lineales del tipo (1) y una serie de preguntas abiertas.In this paper I present the most important results of my research studying the solutions of nonlinear partial differential equations of the type.
In this study, we focus on nonlinear partial differential equations of the form ∆u + λf(u) = 0 in Ω, u = 0 on ∂Ω, where λ ∈ R, Ω is a smooth bounded domain in RN, ∆ = Σ ∂²/∂x²ᵢ is the Laplacian operator, and f : R → R is a nonlinear function. Our theorems were obtained using bifurcation theory, variational methods, and a minmax principle developed by the author in collaboration with A. Castro and J. M. Neuberger ([Cas-Cos-Nu1], 1997). We also present some theorems related to algorithms for approximating solutions to nonlinear problems of type (1), along with a set of open questions
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