1,720,961 research outputs found
Mixture containing calixarenes, process for the production thereof and use thereof for preparing detergent compositions for lubricants
No full textThe present invention relates to mixtures containing calixarenes of
formula (I) with a reduced alkyl phenol and linear oligomer content and the preparation
process thereof, wherein: a. R is selected between a linear or branched alkyl
having a number of carbon atoms comprised between 4 and 40, more preferably
between 4 and 24, even more preferably comprised between 8 and 18; b. n is the
number of units of the calixarene cycle and is comprised in the range from 4 to 16,
preferably between 4 and 12. Furthermore, the present invention relates to detergent
compositions containing overbased metal salts of calixarenes, the preparation
process thereof and the use thereof in lubricant compositions
Metal compounds of calixarenes, detergent compositions and lubricant compositions
No full textThe invention relates to a metal compd. of calixarene not contg. sulfur and dispersible in oil, which can be partially salified, or neutral, or basic or overbased, wherein the calixarene has the general formula (I), where R1, R2, R3 and R4 are independently selected from hydrogen, or a group contg. carbon and hydrogen, or a group contg. heteroatoms in addn. to carbon and hydrogen, provided that the heteroatoms are not sulfur; one of the two substituents R5 and R6 is hydrogen, while the other may be hydrogen, or a linear or branched C1-C6-alkyl, preferably Me, Et, 1-Pr, 2-Pr, Bu, sec-Bu, more preferably Me or ethyl; n is the no. of units of the calixarene ring and is in the range between 4 and 16, preferably between 5 and 12, wherein in at least one of the n units of the calixarene ring, at least one of the substituents R1, R2, R3 and R4 contains at least one carboxylic acid group available for the reaction with a metal base, with the proviso that the carboxylic acid group is not contained in a unit of the calixarene ring derived from salicylic acid. [on SciFinder(R)
Single-Chain Polymer Nanoparticles for Addressing Morphologies and Functions at the Nanoscale: A Review
No full textHydrogenated polymers with a radial structure having a core based on calixarenes and use thereof in lubricant compositions
No full textHydrogenated polymers with a radial structure having a core made up of calixarenes of the general formula I, to the core of which is linked a no. P of hydrogenated linear polymer segments selected from: - hydrogenated homopolymers or copolymers of conjugated dienes; or - hydrogenated copolymers of said conjugated dienes and monoalkenyl arenes, and - mixts. thereof said formula (I) in which: - R1, R2, R3 and R4 are independently selected from hydrogen; a group contg. carbon and hydrogen; a group also contg. heteroatoms in addn. to carbon and hydrogen; a group also contg. silicon in addn. to carbon, hydrogen and heteroatoms; - one of the two substituents R5 and R6 is hydrogen, while the other may be hydrogen or alkyl, with a no. of carbon atoms between 1 and 6, preferably Me and ethyl; - n is an integer in the range between 4 and 16
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
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
Digging into the friction reduction mechanism of organic friction modifiers on steel surfaces: Chains packing vs. molecule–metal interactions
Get PDFWe present a study of five commercially available Organic Friction Modifiers (OFMs) that combines micro-Infrared reflection absorption spectroscopy (IRRAS), classical MD, and DFT/DFT-MD computational methods. We investigate the relation between the molecular structure of the OFMs and their temperature-dependent friction performance. Classical dynamics simulations show that at low temperatures, the OFM molecules, arranged in self-assembled monolayers, undergo collective torsional motion during a friction event. This becomes progressively easier as temperature increases, resulting in lower friction coefficients, until a temperature where these collective motions cannot be maintained anymore, leading to an increase of the friction coefficient. Static DFT calculations indicate that the strength of the packing between OFM molecules determines the friction performance. The temperature at which the collective behavior fails coincides with the temperature at which the packing-free energy is found to diminish
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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