1,721,141 research outputs found
Azobenzene containing polymers: what is yet viable with aged liquid crystals
No full textA Commentary on the paper ”Photochromic liquid crystalline polymers. Main chain and side chain polymers containing azobenzene mesogens„, by A. S. Angeloni, D. Caretti, C. Carlini, E. Chiellini, G. Galli, A. Altomare, R. Solaro and M. Laus. First published in Liquid Crystals, 4, 513‐527 (1989)
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
PTFE-based core-shell nanoparticles preparation and characterization: a route towards the assembly of ordered soft-matter layers with tuneable (photonic) properties
No full textThe assembly of ordered arrangements of nanoparticles can represent a route towards the preparation of materials with innovative physical properties stemming from the characteristics of the nanoparticles themselves and from the controlled interactions amongst them.
Composite materials could exhibit interesting photonic properties if different components are spaced regularly in its bulk: the controlled 2D or 3D assembly of core-shell polymer nanoparticles results in such a regular spacing of the core material. The possibility of controlling the size of the core and the thickness of the shell represents a viable route towards the design of photonic properties towards the realization of nanostructured polymer opals.
PTFE latexes can be obtained with a narrow nanoparticle size distribution. Around such seeds, we could grow shells made of different types of polymers or copolymers that will quantitatively coat the dispersed PTFE seeds. A control of the shell thickness can be obtained by varying the ratio between seed and shell monomer(s). A careful choice of monomers can lead to water-soluble core-shell nanoparticles with markedly different properties. For instance the shell can swell in water (and respond to pH changes) or, alternatively be quite rigid and insensitive to the environment. The comonomers mix will lead to shells with markedly different thermal properties.
In this communication, we report our success in preparing and characterizing a variety of different PTFE-based core-shell systems with shells made with comonomers mixtures such as methylacrylate, ethylacrylate and methacrilic acid, or butylacrylate and methacrilic acid, or simply with methylmethacrylate. Such core-shell nanoparticles have been then used to make ordered layers that have been characterized by atomic force microscopy.
The success in the preparation of these core-shell systems might lead to materials that could exhibit the valuable properties of PTFE while reducing some of its disadvantages, such as its compatibility with other materials (adhesion and wettability). In the near future we will be investigating the possible applications and photonic properties of such regularly arrange nanoparticulate systems
Thermotropic liquid crystal poly(ester-ß-sulphide)s based on twin hexamethylene-spaced p-oxybenzoate diads
No full textVariations 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
Chiral liquid crystalline polymers. XI. Thermotropic behavior and chiroptical properties in solution of a new series of optically active poly(ester ß-sulphide)s
No full text
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
PTFE-based core-shell nanoparticles: a possible way towards the assembly of ordered soft-matter layers with tuneable (photonic) properties
No full textThe assembly of ordered arrangements of nanoparticles can represent a route towards the preparation of materials with innovative physical properties stemming from the characteristics of the nanoparticles themselves and from the controlled interactions amongst them.
Composite materials could exhibit interesting photonic properties if different components are spaced regularly in its bulk: the controlled 2D or 3D assembly of core-shell polymer nanoparticles results in such a regular spacing of the core material. The possibility of controlling the size of the core and the thickness of the shell represents a viable route towards the design of photonic properties towards the realization of nanostructured polymer opals.
PTFE latexes can be obtained with a narrow nanoparticle size distribution. Around such seeds, we could grow shells made of different types of polymers or copolymers that will quantitatively coat the dispersed PTFE seeds. A control of the shell thickness can be obtained by varying the ratio between seed and shell monomer(s). A careful choice of monomers can lead to water-soluble core-shell nanoparticles with markedly different properties. For instance the shell can swell in water (and respond to pH changes) or, alternatively be quite rigid and insensitive to the environment. The comonomers mix will lead to shells with markedly different thermal properties.
In this communication, we report our success in preparing and characterizing a variety of different PTFE-based core-shell systems with shells made with comonomers mixtures such as methylacrylate, ethylacrylate and methacrilic acid, or butylacrylate and methacrilic acid, or simply with methylmethacrylate [1,2]. Such core-shell nanoparticles have been then used to make ordered layers that have been characterized by atomic force microscopy [3].
The success in the preparation of these core-shell systems might lead to materials that could exhibit the valuable properties of PTFE while reducing some of its disadvantages, such as its compatibility with other materials (adhesion and wettability). In the near future we will be investigating the possible applications and photonic properties of such regularly arrange nanoparticulate systems
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