1,721,024 research outputs found
An overview of the recent advances in inorganic nanotubes
Get PDFAdvanced nanomaterials play a prominent role in nanoscience and nanotechnology developments, opening new frontiers in these areas. Among these nanomaterials, due to their unique characteristics and enhanced chemical and physical properties, inorganic nanotubes have been considered one of the most interesting nanostructures. In recent years, important progress has been achieved in the production and study of these nanomaterials, including boron nitride, transition metal dichalcogenide nanotubular structures, misfit-based nanotubes and other hybrid/doped nanotubular objects. This review is devoted to the in-depth analysis of recent studies on the synthesis, atomic structures, properties and applications of inorganic nanotubes and related nanostructures. Particular attention is paid to the growth mechanism of these nanomaterials. This is a crucial point for the challenges ahead related to the mass production of high-quality defect-free nanotubes for a variety of applications. © The Royal Society of Chemistry 2019
Improved Performance p-type Polymer (P3HT) / n-type Nanotubes (WS2) Electrolyte Gated Thin-Film Transistor
No full textThis work decribes the enhancement of the electrical figures of merit of an Electrolyte Gated Thin-Film Transistor (EG-TFT) comprising a nanocomposite of n-type tungsten disulfide (WS2) nanotubes (NTs) dispersed in a regio-regular p-type poly(3-hexylthiophene-2,5-diyl) (P3HT) polymeric matrix. P3HT/WS2 nanocomposites loaded with different concentrations of NTs, serving as EG-TFTs electronic channel materials have been studied and the formulation has been optimized. The resulting EG-TFTs figures of merit (field-effect mobility, threshold voltage and on-off ratio) are compared with those of the device comprising a bare P3HT semiconducting layer. The optimized P3HT/WS2 nanocomposite, comprising a 60% by weight of NTs, results in an improvement of all the elicited figures of merit with a striking ten-fold increase in the field-effect mobility and the on/off ratio along with a sizable enhancement of the in-water operational stability of the device
Unraveling the decomposition pathways of LaS-TaS2 misfit-layered compound nanostructures under extreme electrical currents by in situ TEM
No full textNanostructures of the misfit-layered compound (MLC) LaS-TaS2 are brought to breakdown by application of high electrical currents within a transmission electron microscope. Imaging, diffraction, and spectroscopy techniques are employed to study their decomposition process and the resulting structures. The main decomposition route is the breakdown of the TaS2 layers, which induces the formation of metallic Ta on the surface of the nanostructures when the critical current density is surpassed. This observation confirms the assumption that TaS2 is the current-carrying layer in these types of MLCs. The different behavior of tubular 1D and 2D structures is revealed, and a metallic glass phase made of La, Ta, and S could be observed upon exceeding a threshold current. The work shows how in situ transmission electron microscopy can help understand the breakdown mechanism of electrical devices or connectors.SH and RA acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 889546, from the Spanish MICIU ((PID2023-151080NB-I00/AEI/10.13039/501100011033), from the Spanish MICIU with funding from European Union Next Generation EU(PRTR-C17.I1) promoted by the Government of Aragon as well as from the “Severo Ochoa” Programme for Centres of 758 Excellence in R&D of the Spanish MICIU (CEX2023-759 001286-S MICIU/AEI/10.13039/501100011033) and the Government of Aragon (DGA) through the project E13 23R. RT acknowledges the support of the Estate of Manfred Hecht and the Estate of Diane Recanati and the Perlman family foundation. The microscopy and spectroscopy works have been conducted in the Laboratorio de Microscopias Avanzadas (LMA) at Universidad de Zaragoza. The authors thank I. Echaniz and N. Navascuez (INMA) for help with Raman spectra acquisition.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2023-001286-S).Peer reviewe
Atomic structural studies on thin single-crystalline misfit-layered nanotubes of TbS-CrS2
No full textVarious nanotubes from ternary misfit compounds have been reported in recent years. In the present work, the detailed atomic structure and chemical configuration of misfit-layered nanotubes based on the TbS-CrS2 are reported. These analyses have been developed via different transmission electron microscopy techniques, including high-resolution scanning transmission electron microscopy, electron diffraction, and electron energy loss spectroscopy. These structural analyses show that two different kinds of nanotubes can be produced: a “regular” nanotube and a “wavy” one. Both kinds of nanotubes show the alternating arrangements of the TbS and CrS2 subsystems; however, the wavy ones present a nearly periodically deficiency in terbium. In addition to the structural investigation, the chemical analyses have proved that the outer layer of both kinds of nanotubes is composed of the elements Cr and S. All these findings helped to understand the growth mechanism during the sulfurization reaction taking place in the synthesis process.Some of the research leading to these results has received funding from the European Union Seventh Framework Program under Grant Agreement 312483 - ESTEEM2 (Integrated Infrastructure Initiative - I3) and under Grant Agreement 604391 Graphene Flagship. R.A. also acknowledges funding from the Spanish Ministerio de Economia y Competitividad (FIS2013-46159-C3-3-P). R.T. acknowledges the support of the Israel Science Foundation; the Israel National Nano-Initiative through its Focal Technology Areas program; the H. Perlman Foundation; the Irving and Azelle Waltcher Foundations in honor of Prof. M. Levy; and the Irving and Cherna Moskowitz Center for Nano and Bio-Nano Imaging. L.S.P. would like to thank the PBC Program of the Government of Israel and the Dean of the chemistry faculty, Weizmann Institute of Science, for a postdoctoral fellowship.Peer reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Torsional resonators based on inorganic nanotubes
No full textWe study for the first time the resonant torsional behaviors of inorganic nanotubes, specifically tungsten disulfide (WS<sub>2</sub>) and boron nitride (BN) nanotubes, and compare them to that of carbon nanotubes. We have found WS<sub>2</sub> nanotubes to have the highest quality factor (<i>Q</i>) and torsional resonance frequency, followed by BN nanotubes and carbon nanotubes. Dynamic and static torsional spring constants of the various nanotubes were found to be different, especially in the case of WS<sub>2</sub>, possibly due to a velocity-dependent intershell friction. These results indicate that inorganic nanotubes are promising building blocks for high-<i>Q</i> nanoelectromechanical systems (NEMS)
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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