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Hypergolic ignition by head-on collision of N,N,N',N'-tetramethylethylenediamine and white fuming nitric acid droplets
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Hypergolic ignition by the head-on collision of a smaller N,N,N',N' tetramethylethylenediamine (TMEDA) droplet and a larger white fuming nitric acid (WFNA) droplet was experimentally investigated by using a droplet collision experimental apparatus equipped with a time-resolved shadowgraph, a photodetector and an infrared detector. The investigation was focused on understanding the influence of droplet collision and mixing, which vary with the collisional Weber number (We = 20-220) and the droplet size ratio (Delta = 1.2-2.9) while have a fixed Ohnesorge number (Oh = 2.5x10(-3)), on the hypergolic ignitability and the ignition delay times. The hypergolic ignition was found to critically rely on the heat release from of the liquid-phase reaction of TMEDA and nitric acid, which is subsequent to and enhanced by the effective mixing of the droplets of proper size ratios. Consequently, the ignitability regime nomogram in the We-A space shows that the hypergolic ignition favors small Delta s and large Wes; the ignition delay times tend to decrease with either decreasing Delta, or increasing We, or both. A non-monotonic variation of the ignition delay times with We was observed and attributed to the non-monotonic emergence of jet-like mixing patterns that enhance the droplet mixing and hence the liquid-phase reaction. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.</p
Catalytic Olefin Transpositions Facilitated by Ruthenium N,N,N-Pincer Complexes
No full textPrevious reports with our N,N,N-pincer Ru-hydride catalysts have shown their synthetic versatility toward various transfer hydrogenation reactions and pi-bond functionalizations. In this report, we expand the reactivity of these complexes to encompass olefin transposition/isomerizations. The protocol proceeds at room temperature for most substrates, achieving excellent yields, regioselectivity, and diastereoselectivity in short reaction times. Furthermore, we demonstrate the potential for one-pot cascade sequences of the products derived from the transposition reactions
Structural Trends and Vibrational Analysis of N,N,N′,N′- Tetramethylmalonamide Complexes Across the Lanthanide Series
No full textFundamental understanding of coordination chemistry across the lanthanide series is essential for explaining chemical behavior of rare-earth metals in complex liquid-liquid extraction processes, which in turn affects the distribution ratios and efficacy of separations as a whole. In this work, we explore the structural trends between the lanthanides and a neutral N,N,N′,N′-tetramethylmalonamide (TMMA) ligand within four isolated families of solid-state compounds: Ln(trans-TMMA)2(NO3)3 Ln = La-Nd, Sm; Ln(cis-TMMA)2(NO3)3 Ln = Eu-Tb, Er; [Ln(TMMA)3(NO3)2][Ln(TMMA)(NO3)4] Ln = Dy-Tm; Ln(Κ2-TMMA)(iPrOH)(NO3)3 and Ln(Κ1-TMMA)(Κ2-TMMA)(NO3)3 Ln = Yb, Lu. Moving across the lanthanide series, we note the formation of both discrete charge-neutral complexes, as well as charged molecular anion-cation pairs, with variations in spatial ligand arrangement, coordination numbers, and ligand denticities. IR and Raman spectroscopy paired with DFT frequency calculations were used for an in-depth investigation of vibrational modes unique to each structural family. The collection of isolated model compounds was also discussed in the context of liquid-liquid separations based on reported distribution ratios from malonamide extraction
Eigenhändiger Brief mit Unterschrift an N. N.
No full textEIGENHÄNDIGER BRIEF MIT UNTERSCHRIFT AN N. N.
Eigenhändiger Brief mit Unterschrift an N. N. (1)
Letter (1)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Electroluminescence of tetradentate Pt(II) complexes: O^N^N^O versus C^N^N^O coordination
No full textAlkylation of one of the phenolic hydroxyl groups in a silene-type tetradentate ligand changes the coordination mode from O^N^N^O to cyclometallating C^N^N^O type. The ligand was used to synthesise a new cyclometallated luminescent Pt(II) complex 2. While in solution the complex is poorly luminescent, in the solid state the emission is reinstated which allowed to evaluate the complex 2 as phosphorescent emitter in organic light emitting devices (OLEDs). 2 displays EQE = 9.1 % and maximum luminance of 9000 cd m-2 in a vacuum deposited device. We carried out comparative analysis of photo- and electroluminescence of complex 2 with O^N^N^O complex 1 and demonstrated that the similar luminescent properties of O^N^N^O and C^N^N^O complexes are rather coincidental as they display different excited state landscapes. Surprisingly, the two complexes display a dramatically different electrochemical behaviour with the O^N^N^O coordination leading to formation of a stable electropolymer, but C^N^N^O coordination fully preventing electropolymerisation
Variations on the Author
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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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