1,720,964 research outputs found
Langmuir-Blodgett films of a pyrrole derivative polymerized as a monolayer
No full textWe report a study of the polymerization kinetics of a pyrrole derivative monolayer at the interface between air and an oxidating subphase. The resulting polymer features a bidimensional chain structure, which is more ordered than a bulk prepared polymer. The transfer of the monolayer onto solid substrates yielded good Langmuir-Blodgett (LB) films, which were spectroscopically characterized in the UV, visible and IR regions. The high-frequency (IR) conductivity of the LB films prepared from such monolayers was higher than that of the films deposited from the bulk polymerized material
Gold nanoparticles-polyaniline composite material: Synthesis, structure and electrical properties
No full textGold nanoparticles-polyaniline composite materials were synthesised and their structure and electrical properties were analised. Different stabilizing agents were used resulting in the formation of nanoparticles with sizes within 5-10 nm. The best results were obtained when the composite material was obtained during the polymerization of the anilinium salt in the presence of the mixture composed by dodecyl benzene sulfonic acid and 2-mercaptoethanesulfonic acid stabilized gold nanoparticles. Electrical properties of this composite material demonstrated the formation of Schottky barriers between polyaniline and gold particles, an essential property for its use in bio-inspired complex information handling material
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
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
Balance in patients with anorexia and bulimia nervosa
No full textAim. Neuro-muscular adaptations to the loss or increase in body weight may induce postural alterations. The aim of this study was to investigate the effect of body weight alterations on postural stability in patients with anorexia nervosa and bulimia. Methods. The study enrolled 15 women affected by anorexia nervosa (AN), (mean body mass index [BMI] 15.8 +/- 1.8 kg/m(2)), 15 women affected by bulimia nervosa (BN), (mean BMI 20.1 +/- 2.9 kg/m(2)) and 11 healthy matched women (HC), (mean BMI 20.1 +/- 1 kg/m(2)). Two quiet standing conditions with eyes open (EO) and closed (EC) were analysed with an optoelectronic system (Vicon 460, Viconpeak, Oxford, UK) with passive markers to estimate the centre of mass (CoM) position. Results. BN patients were more unstable than HC, showing statistically significant differences in antero-posterior CoM excursions and path length. AN patients showed non significant differences from HC. Only HC showed differences between EO and EC conditions, with significantly greater excursions in medio-lateral direction in EC condition (P<0.013) as well as an increased sway area (P<0.022). Conclusion In BN, musculoskeletal factors seem to play a major role in the diminished postural control, which appear to be linked to body weight fluctuations rather than to BMI absolute values. No clear-cut postural instability was demonstrated in patients with AN as compared to HC. Visual input appears not to affect balance in patients with eating disorders. Possible further causes of postural instability in BN and implications for rehabilitation treatment are discussed
MICROSCOPIC TRANSPORT-PROPERTIES IN LIQUID-CRYSTALLINE POLYMERIC MATRICES - DEPENDENCE ON THE THERMAL HISTORY
No full textThe dependence on the thermal history of the dynamical and structural properties of a polymer liquid crystal has been evidenced by differential scanning calorimetry, infrared dichroism and non-linear electron spin resonance (ESR) spectroscopy in a wide range of temperatures. The behaviour of the microscopic viscosity as a function of both the isothermal annealing and the temperature is studied and its salient features are interpreted in terms of cooperativity. The multiexponential decay of the orientation correlation functions, relevant in the relaxation processes of linear and non-linear ESR spectroscopies, occurs in the supercooled and glassy phases, whereas the single exponential decay recovers above the isotropization temperature
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