3,634 research outputs found
Role of carbonate amount and synthesis procedure in the conductivity of SDC-Na2CO3 composite electrolytes for solid oxide cells applications
No full textComposite electrolytes of sodium carbonate and samarium doped ceria (SDC-Na2CO3) provide outstanding proton conductivity between 300 °C and 650 °C, which is extremely sensitive to the synthesis procedure and to the amount and crystallinity of the carbonate phase. Here, the role of sodium carbonate in establishing the composite conductivity is explored in relation to chemical-structural and morphological characterization methods (ICP, XRD, SEM, TEM). A coprecipitation route is properly optimized to prepare composites with <50 nm SDC particles with sodium carbonate in different amounts. The amount of carbonate, carefully quantified via elemental analysis, strongly influences the proton conductivity, while the oxygen ion conductivity is much less affected. The formulation with 27 wt% of carbonate prepared through a single-step synthesis shows the best performance, with 2.27*10^−2 S cm^−1 proton conductivity in dry hydrogen (4 % H2 in N2) at 600 °C, and 1.73*10^−2 S cm^−1 oxygen ion conductivity in air. Interestingly, an SDC-Na2CO3 composite containing the same salt amount but produced via a double-step procedure showed lower conductivity, confirming the pivotal role of the preparation methodology in defining the composite proton conductivity. In addition, humidification is found to depress H+ conductivity, thus indicating that the preferential charge transport mechanism does not involve hydroxides, in contrast to conventional protonic ceramics. Overall, the investigation reveals a strong dependence of the composite proton conductivity on the density of the carbonate/SDC interfaces and the crystallinity of the carbonate
Highly transparent Bi4Ti3O12 thin-film electrodes for ferroelectric-enhanced photoelectrochemical processes
No full textIn a photo-electrochemical (PEC) cell, rapid spatial separation of the photo-generated carriers and their transport kinetics within the photo-electrode materials are fundamental to achieving high-performance devices and avoiding charge recombination. Recently the use of ferroelectric potential in ferroelectric photo-active semiconductors has shown to be an effective strategy to modulate the charge transfer properties both in the bulk phase and at the surface of semiconductors. In this perspective, the Aurivillius perovskite Bi4Ti3O12 (BiTO) is of great interest owing to its excellent photocatalytic activity and strong spontaneous ferroelectric polarization. The use of BiTO powder for the photocatalytic reduction of CO2 has recently been reported, but its utilization as a photo-electrode for the photo-electrochemical (PEC) reduction of carbon dioxide has never been exploited, especially assisted by a ferroelectric potential. In this work, highly transparent BiTO-based thin film photo-cathodes were fabricated via a sol-gel/spin coating coupled process and optimized, for the first time in the literature, for CO2 PEC reduction. The influence of the number of depositions on the photo-electrochemical properties was initially accurately investigated and an optimized photo-electrode was thus obtained, which registered a maximum current density of -4.1 mA cm(2) under illumination conditions. In addition, the effect of the ferroelectric potential on the photo-electrochemical performances was accurately studied in this optimized system producing a current density increment of about 50% and an enhanced charge transfer ability, thus demonstrating the possibility of effectively adopting ferroelectric polarization in BiTO photo-electrodes to boost the photo-electrochemical reduction of CO2
Professor Angela Shannon
No full textAngela Shannon shares her poetry with the Taylor community.
Angela Shannon is the author of Singing the Bones Together, a 2004 Minnesota Book Awards Finalist. She teaches English at Bethel University. Her work has been published in journals, textbooks, and anthologies, including TriQuarterly, Ploughshares, Where One Ends Another Begins: 150 Years of Minnesota Poetry, and Beyond the Frontier: African American Poetry for the 21st Century. Her choreopoem Root Woman premiered at the Fleetwood-Jourdain Theater in Evanston, Ill
Angela Shanté : 2022 Irma Black Award Silver Medal Acceptance Speech
No full textAuthor Angela Shanté gives an acceptance speech for When My Cousins Come to Town, illustrated by Keisha Morris (West Margin Press)https://educate.bankstreet.edu/irma_black_awards/1004/thumbnail.jp
The Family History of Angela Ruth Weidert
No full textAngela Ruth Weidert authored this family history as part of the course requirements for HIST 550/700 Your Family in History offered online in Spring 2018 and was submitted to the Pittsburg State University Digital Commons. Please contact the author directly with any questions or comments: [email protected]
Role of the sintering atmosphere in the densification and phase composition of asymmetric BCZY-GDC composite membrane
No full textCeramic hydrogen separation membranes are promising devices to be integrated in industrial hydrogen-based technologies using fossil fuel as feedstock. Among all, BaCe0.65Zr0.20Y0.15O3-δ–Ce0.8Gd0.20O2-δ composite membrane is the most promising ceramic-ceramic system for such application. However, one of the main issues in Ba-containing perovskites is related to Ba loss at the high sintering temperature needed for the complete densification of the material. This work reports the influence of the sintering atmosphere and temperature on the membrane’s densification and phase purity. BaCeO3 (BC), BaCe0.65Zr0.20Y0.15O3-δ (BCZY) and a BaCe0.65Zr0.20Y0.15O3-δ–Ce0.8Gd0.20O2-δ (BCZY-GDC) mixture were used as Ba-sources to modify the sintering atmosphere. The more reactive BC and BCZY systems promoted a solid-state reaction between BCZY and GDC leading to an undesired single mix-phase enriched in barium on the membrane’s surface. The desired asymmetric architecture with the correct stoichiometry was obtained using BCZY-GDC as Ba-source and sintering the membrane at 1550 °C
Alternative production route for supporting La0.8Sr0.2MnO3 -Ce0.8Gd0.2O2 (LSM-GDC)
No full textTape casting is a widely used ceramic process that generally makes use of pore former agents to produce elements with engineered porosity for SOFC applications. In this work, porous La 0.8 Sr 0.2 MnO 3-δ-Ce 0.8 Gd 0.2 O 2-δ (LSM-GDC) supporting cathode of suitable porosity was produced using the reactive sintering approach without using of pore forming agent
Materia-autore = Author-Matter
No full textThe etymology of the word author refers to an act of creation, an act of augmentation, from the Latin verb augere. Author instantiates creation, the expansion of the pre-existing. In 1967 Roland Barthes declared the death of the author in his famous essay to state once more that the crisis is that of the author as a single subjectivity and as a term that condenses prestige, undermined by the de-subjectivation strategies of automatism, fortuity and fragmentation of the historical avant-gardes, as well as by the machinic act and by the reproducibility of the second avant-gardes.
Fifty years after Barthes’ paradigmatic formula, this lack of authorship appears to be a successful brand. The ten- sions between the anomie of matter, the law that establishes authorship and the economy that makes the work pos- sible, invoke discordant perspectives. Artists make the self-destruction of their work the real work, and appeal is made for the demolition of architectures, whether by a recognised author or not, in order to re-design, or better still, re-claim the territory. Artificial intelligence consolidates its logics and its design by progressively shedding human ingenuity. The space of criticism becomes, finally, increasingly ephemeral. However, there is an acceptation of criti- cism that is, rather than an individual ‘signature’, an exploration and explanation of how design makes theory.
The binomial author-matter seeks to mark these tensions and contradictions: the featured term author is main- tained to underline the persistence of that prestigious subjectivity, at the very moment when the rhetoric of “mat- ter as an author” promises other forms of authorship
Giussani Sansoni, Angela
No full textLa scheda ricostruisce la vita e l'apporto della scrittrice Angela Giussani Sansoni alla letteratura per l'infanzia.The headword explains the biography and the contribution of the author Angela Giussani Sansoni to the children's literature
Deliberation and journalism
No full textThe first chapter in 'International Journalism and Democracy' re-examines current ideas about the role of journalism in promoting democracy, introducing the concept of "deliberative journalism". 'Deliberation and Journalism' lists the ways in which journalists can assist deliberation and politics in communities around the world. The chapter defines deliberation as a specific form of conversation that precedes and promotes decision-making and action by members of a community. The author recognises the difficulty of engaging in deliberation in communities that are divided by different interests, identities, backgrounds, resources and needs. She provides examples of strategies that journalists can use to encourage inclusive and productive deliberation in the face of community diversity.\ud
\ud
The chapter introduces examples of types of deliberative journalism that have emerged around the globe. These include strategies that have been sometimes been labeled as public journalism, civic journalism, peace journalism, development journalism, citizen journalism, the street press, community journalism, environmental journalism, and social entrepreneurism. The chapter also includes models of journalism that have not yet been given any particular name. Although the book identifies problems surrounding the theory and practice of these forms of journalism, the author notes that this is to be expected. Most models of deliberative journalism are relatively new, with none being more than a few decades old. The author concludes that resolution of these problems will only occur incrementally
- …
