1,720,970 research outputs found
Study of temperature dependence and angular distribution ofpoly(9,9-dioctylfluorene) polymer films deposited by matrix-assisted pulsed laserevaporation (MAPLE)
Full text linkPoly(9,9-dioctylfluorene) (PFO) polymer films were deposited by matrix-assisted pulsed laser evaporation (MAPLE) technique. The polymer was diluted (0.5 wt%) in tetrahydrofuran and, once cooled to liquid nitrogen temperature, it was irradiated with a KrF excimer laser. 10,000 laser pulses were used to deposit PFO films on 〈1 0 0〉 Si substrates at different temperatures (−16, 30, 50 and 70 °C). One PFO film was deposited with 16,000 laser pulses at a substrate temperature of 50 °C. The morphology, optical and structural properties of the films were investigated by SEM, AFM, PL and FTIR spectroscopy. SEM inspection showed different characteristic features on the film surface, like deflated balloons, droplets and entangled polymer filaments. The roughness of the films was, at least partially, controlled by substrate heating, which however had the effect to reduce the deposition rate. The increase of the laser pulse number modified the target composition and increased the surface roughness. The angular distribution of the material ejected from the target confirmed the forward ejection of the target material. PFO films presented negligible modification of the chemical structure respect to the bulk material
Pulsed laser deposition of organic and biological materials
Full text linkWe report on the deposition of soft matter thin films by Matrix Assisted Pulsed Laser Evaporation (MAPLE). In particular, thin layers of biological material (Bovine Serum Albumin) and polymers (polyfluorene) for medical and optoelectronic applications, were realized by laser irradiating a frozen solution containing a low amount of material diluted in a laser absorbing volatile solvent. The depositions were carried out varying different parameters as solvent–solute concentration, solvent nature, laser fluencies, etc. The optical, morphological, structural and spectroscopical properties were detected by means of different analyses as FTIR, photoluminescence, AFM and SDS
Aluminum-doped zinc oxide coatings on polylactic acid films for antimicrobial food packaging
No full textPolylactic acid (PLA) is safe for contact with food, flexible and highly transparent to visible light, so it is widely used for food packaging applications. The addition of proper surface coatings can provide further advantages, such as antimicrobial activity and optimized optical properties. To this aim, nanostructured aluminum-doped zinc oxide (AZO) coatings were sputter-deposited onto extruded PLA film to functionalize its surface, using different sputtering power. Morphological, structural and optical characterizations were performed on uncoated and coated films, demonstrating uniform coverage of the PLA substrate with polycrystalline AZO coatings and high visible transparency. Spectrophotometric measurements carried out on physiological saline solutions containing the samples revealed low release effects from the uniformly-coated films. Finally, the sputter-coated samples exhibited strong antibacterial activity against Escherichia coli. The results of this preliminary study indicate that AZO-coated PLA films are promising materials for environment-friendly active packaging applications
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
Antibacterial Surfaces, Thin Films, and Nanostructured Coatings
Full text linkCreating antibacterial surfaces is the primary approach in preventing the occurrence and diffusion of clinical infections and foodborne diseases as well as in contrasting the propagation of pandemics in everyday life. Proper surface engineering can inhibit microorganism spread and biofilm formation, can contrast antimicrobial resistance (AMR), and can avoid cross-contamination from a contaminated surface to another and eventually to humans. For these reasons, antibacterial surfaces play a key role in many applications, ranging from biomedicine to food and beverage materials, textiles, and objects with frequent human contact. The incorporation of antimicrobial agents within a surface or their addition onto a surface are very effective strategies to achieve this aim and to properly modify many other surface properties at the same time. In this framework, this Special Issue collects research studying several materials and methods related to the antibacterial properties of surfaces for different applications and discussions about the environmental and human-safety aspects
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
Possible alternatives to critical elements in coatings for extreme applications
Full text linkE-MRS Fall Symposium I: Solutions for Critical Raw Materials Under Extreme Conditions
18–21 September 2017, Warsaw, PolandSurface functionalisation and protection have been used since a long time for improving specific properties of materials such as lubrication, water repellence, brightness, and for increasing durability of objects and tools. Among the different kinds of surface treatments used to achieve the required properties, the use of coatings is fundamental to guarantee substrate durability in harsh environments. Extreme working conditions of temperature, pressure, irradiation, wear and corrosion occur in several applications, thus very often requiring bulk material protection by means of coatings. In this study, three main classes of coatings used in extreme conditions are considered: i) hard and superhard coatings for application in machining tools, ii) coatings for high temperatures (thermal barrier coatings), and iii) coatings against corrosion. The presence of critical elements in such coatings (Cr, Y, W, Co, etc.) is analysed and the possibility to use CRMs-free substitutes is reviewed. The role of multilayers and nanocomposites in tailoring coating performances is also discussed for thermal barrier and superhard coatings.COST Action “Solutions for Critical Raw Materials under Extreme Conditions”, supported by COST
(European Cooperation in Science and Technology) and H2020 Grant Agreement TWINNING
692216 "The virtual Center for sustainable development of Advanced Materials operating under
extreme conditions"- Acronym SUPERMA
- …
