1,721,003 research outputs found
The pH- And salt-controlled self-assembly of [1]benzothieno[3,2-b][1]-benzothiophene-peptide conjugates in supramolecular hydrogels
No full textHere, we report a [1]benzothieno[3,2-b][1]-benzothiophene (BTBT) derivative functionalized with a β-sheet-forming peptide which alternates in its sequence Phe and Glu residues. The BTBT core is a popular structural motif in the design of high-mobility organic semiconductors. The insertion of the self-assembling subunit allows control of the supramolecular organization. This molecule self-assembles in water to give hydrogels over a broad range of pH values. Hydrogelation is triggered by both pH changes and variations in salt concentrations. Transmission electron microscopy shows the formation of long-range self-assembled 1D structures. The key role of hydrogen bonding and π-π interactions in hierarchical self-assembly is investigated using absorption, emission, infrared and circular dichroism spectroscopy. This is the first example of demonstrating the formation of supramolecular hydrogels containing the BTBT structure
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
Solution-processable thin-film transistors from anthradithiophene (ADT) and naphthothiopene (NT) small molecule-based p-type organic semiconductors
No full textSustainable green electronics is increasingly needed for a multitude of new applications that will fill daily life in the coming decades. The search for new semiconductor materials that can be used in light, flexible, ultra-thin and scalable devices has been given great attention, and especially directed towards organic materials, such as small molecules or polymers. One of the main strengths in such materials lies in those applications where it is not only important to achieve high performance in terms of electronic mobility but it is essential to have low temperatures, solution-processable, and low-cost manufacturing processes. We present the synthesis of novel, organic, solution-processable, small molecule semiconductor materials based on key synthons (ADT and NT) obtained through sustainable processes. Such p-type, pi-conjugated molecular scaffolds have been obtained through cascade reaction sequences involving, amongst others, direct arylation protocols and cross-aldol condensations, affording organic compounds with intrinsically low E factors. We have realized air-stable, organic thin film transistors with very good performances, and demonstrated their use as UV-VIS photodetecting transistors with responsivity values matching currently available commercial detectors
Push-pull organic chromophores for frequency up-converted lasing
No full textProperly designed organic molecules where a π-conjugated bridge is end-capped by an electron-donor and electron-withdrawing group (push–pull chromophores) can show, under specific conditions, frequency-upconverted lasing emission. Materials based on these dyes are therefore able to convert the emission of a cheap and easily available infrared (IR) laser (e.g., 800 nm radiation) into more useful visible (vis) laser emission via a two-photon absorption induced fluorescence phenomenon. The design of the molecular structure, the substituent effect, and modulation of the electronic and geometric parameters can be used in order to optimize and tune frequency emission and conversion efficiency. Examples of some of the best dyes reported to-date and organic design strategies employed are discussed in this article
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
Thermochromic Latent-Pigment-Based Time-Temperature Indicators for Perishable Goods
No full textThe development of cheap and reliable time-temperature indicators (TTIs) can greatly improve customer satisfaction with respect to the correct handling and storage of perishable goods. A series of new irreversible thermochromic squaraine dyes enables the preparation of simple TTIs whose time-temperature regime can be controlled by selection of the appropriate molecule/substrate combinations
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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