1,720,992 research outputs found
CVD Polymer Surfaces for Biotechnology and Biomedicine
No full textRecent developments in biotechnology and biomedicine have been boosted by the rational design of devices with biomimetic functions, specific cellular responses, or tissue-mediated biomolecular recognition. Chemical vapor deposition (CVD) polymers, in particular, are also easily patterned and shaped, so they can be readily integrated on different types of substrates and spatially resolved biodevices, at room temperature, without altering the mechanical properties of the bulk materials. The translation of the capabilities of CVD polymers finds direct application in device fabrication (e.g., biosensors, drug delivery system, biological microelectrochemical systems (BioMEMS)), tissue engineering, and biopassivating and antimicrobial coating deposition on clinically used biomaterials. CVD surface modification techniques currently applied in biomedicine and biotechnology include plasma-enhanced CVD (PECVD), vapor-phase polymerization (VPP), initiated CVD (iCVD), oxidative CVD (oCVD), and parylene. The diversity of applications for CVD polymers is anticipated to expand for the new generation of functional surfaces and devices
Special Section on “Materials Technologies for Controlling Liquid–Surface Interactions from Wetting to Icing”
No full textThe control of liquid–surface interactions is a fundamental principle in materials science and engineering, influencing a vast array of applications, from energy systems, where tailored wettability enhances heat transfer and fluid dynamics, to biomaterials, where surface properties dictate cell adhesion, biofouling prevention, and drug delivery, liquid–surface interactions remain pivotal. Their role extends further into microfluidics, enabling precise manipulation of droplets in lab-on-a-chip devices and into stimuli-responsive materials, where controlled wetting behavior dictates adaptive and functional performance.
A cornerstone in our understanding of wetting behavior was Young's equation (1805), which established the balance of interface forces at the three-phase contact line, defining the equilibrium contact angle of a liquid droplet on a solid substrate. Followed by the pioneering studies by Wenzel (1936) and Cassie–Baxter (1944), which further refined this knowledge by introducing wetting models that explain how surface roughness and chemistry influence liquid behavior. The Wenzel model describes liquid infiltration into textured surfaces, leading to strong adhesion, while the Cassie–Baxter model highlights the formation of air pockets on structured surfaces, resulting in extreme water repellency. These principles laid the groundwork for modern surface engineering, guiding the development of superhydrophobic coatings, icephobic materials, and adaptive wetting surfaces. Building upon these fundamentals and drawing inspiration from nature, including the hierarchical microstructures of lotus leaves, the rose petal effect, and hydrophobic adaptations in animal fur and insect legs, scientists have engineered precise wettability control to create surfaces with remarkable water management properties. These innovations have unlocked new functionalities, including self-cleaning coatings, enhanced water repellency, and responsive wetting control, with materials ranging from superhydrophobic and oleophobic surfaces to slippery liquid-infused porous films (SLIPS) and amphiphilic coatings.This work was funded by the EU H2020 program under grant agreement 899352 (FETOPEN-01-2018-2019-2020 – SOUNDofICE), TED2021-130916B-I00 funded by MCIN/AEI/10.13039/501100011033, ERDF (FEDER), and “A way of making Europe, Fondos NextgenerationEU and Plan de Recuperación, Transformación y Resiliencia” and from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 956703 (SURFICE Smart surface design for efficient ice protection and control).Peer reviewe
Tuning the Porosity of Piezoelectric Zinc Oxide Thin Films Obtained from Molecular Layer-Deposited “Zincones”
Full text linkPorous zinc oxide (ZnO) thin films were synthesized via the calcination of molecular layer-deposited (MLD) “zincone” layers. The effect of the MLD process temperature (110 °C, 125 °C) and of the calcination temperature (340 °C, 400 °C, 500 °C) on the chemical, morphological, and crystallographic properties of the resulting ZnO was thoroughly investigated. Spectroscopic ellipsometry reveals that the thickness of the calcinated layers depends on the MLD temperature, resulting in 38–43% and 52–56% of remaining thickness for the 110 °C and 125 °C samples, respectively. Ellipsometric porosimetry shows that the open porosity of the ZnO thin films depends on the calcination temperature as well as on the MLD process temperature. The maximum open porosity of ZnO derived from zincone deposited at 110 °C ranges from 14.5% to 24%, rising with increasing calcination temperature. Compared with the 110 °C samples, the ZnO obtained from 125 °C zincone yields a higher porosity for low calcination temperatures, namely 18% for calcination at 340 °C; and up to 24% for calcination at 500 °C. Additionally, the porous ZnO thin films were subjected to piezoelectric measurements. The piezoelectric coefficient, d33, was determined to be 2.8 pC/N, demonstrating the potential of the porous ZnO as an, e.g., piezoelectric sensor or energy harvester
Humidity Responsive Reflection Grating Made by Ultrafast Nanoimprinting of a Hydrogel Thin Film
No full textThe response time of state of the art humidity sensors is approximately 8 s. A faster tracking of humidity change is especially required for health care devices. We focused our research on the direct nanostructuring of a humidity-sensitive polymer thin film and combined it with an optical read-out method. Our goal was to improve the response time by changing the surface-to-volume ratio of the thin film and to test a different measurement method compared to state of the art sensors. Large and homogeneous nanostructured areas were fabricated by nanoimprint lithography on poly(2-hydroxyethyl methacrylate) thin films. Those thin films were made by initiated chemical vapor deposition (iCVD). To the author's knowledge, this is the first time nanoimprint lithography was applied on iCVD polymer thin films. With the imprinting process we developed a diffraction grating in the visible wavelength regime. The optical and physicochemical behavior of the nanostructures was modeled with multi-physic simulations. After successful modeling and fabrication a first proof of concept showed that humidity dependency by using an optical detection of the first diffraction order peak is observable. The response time of the structured thin film resulted to be at least three times faster compared to commercial sensors. This article is protected by copyright. All rights reserved
On the transformation of “zincone”-like into porous ZnO thin films from sub-saturated plasma enhanced atomic layer deposition
Full text linkThe synthesis of nanoporous ZnO thin films is achieved through annealing of zinc-alkoxide (“zincone”-like) layers obtained by plasma-enhanced atomic layer deposition (PE-ALD). The zincone-like layers are deposited through sub-saturated PE-ALD adopting diethylzinc and O2 plasma with doses below self-limiting values. Nanoporous ZnO thin films were subsequently obtained by calcination of the zincone-like layers between 100–600 °C. Spectroscopic ellipsometry (SE) and X-ray diffraction (XRD) were adopted in situ during calcination to investigate the removal of carbon impurities, development of controlled porosity, and formation and growth of ZnO crystallites. The layers developed controlled nanoporosity in the range of 1–5%, with pore sizes between 0.27 and 2.00 nm as measured with ellipsometric porosimetry (EP), as a function of the plasma dose and post-annealing temperature. Moreover, the crystallinity and crystallite orientation could be tuned, ranging from a powder-like to a (100) preferential growth in the out-of-plane direction, as measured by synchrotron-radiation grazing incidence XRD. Calcination temperature ranges were identified in which pore formation and subsequent crystal growth occurred, giving insights in the manufacturing of nanoporous ZnO from Zn-based hybrid materials
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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