1,721,459 research outputs found
Atio and Andra
No full textb&w photographCondition: GoodScope and Content: Two children, Atio and Andra, sitting in the sand near cooking pots. Two people in the background, one weaving a basket
A rapid method for the synthesis of perovskite (ATiO(3), A = Ca, Sr, Ba) in molten chloride
No full textThis paper reports the rapid synthesis of perovskite (ATiO(3), A = Ca, Sr, Ba) via molten salt method within 10 min BaCl2 or CaCl2 was used due to their excellent solubility of O2- which enables faster mass transfer transport in the liquid phase. TiO2, ACl(2) and CaO (or BaCO3) were used as the precursors. The obtained ATiO(3) show high chemical and phase purity. Studies found that cation size in ATiO(3) plays an important role in the transformation between different perovskites. The method may provide a generalized methodology for rapid preparation of other important perovskites
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
Simultaneous improvement of power density and durability of sulfonated poly(ether ether ketone) membrane by embedding CeO2-ATiO(2): A comprehensive study in low humidity proton exchange membrane fuel cells
No full textHerein, we describe the incorporation of cerium oxide-coated amine-functionalized titania nanorods (CeO2-ATiO(2)) as a bifunctional nanofiller in sulfonated poly(ether ether ketone) (SPEEK) as a cost-effective and high-performance proton exchange membrane (PEM) for PEM fuel cells (PEMFCs). Facile and effective functionalization of TiO2 was performed using amine-containing organic moieties, followed by coating the ATiO(2) nanorods with CeO2. A simple solution casting method was employed to incorporate CeO2-ATiO(2) into the SPEEK matrix with various weight ratio of 0.5%, 1%, 2%, 4%, or 6%. The successful incorporation of prepared nanofiller in the SPEEK membrane matrix was confirmed by structural and morphological studies such as Fourier transform infrared, X-ray diffractometer, scanning electron microscopy, and atomic force microscope of the SPEEK/CeO2-ATiO(2) composite membranes. The presence of ATiO(2) improved proton conductivity while CeO2 alleviated the chemical degradation of the membrane by scavenging free radicals. The proton conductivity of an SPEEK/CeO2-ATiO(2) (2 wt%) nanocomposite membrane at 60 degrees C under 20% relative humidity (RH) was 17.06 mS cm(-1) whereas that of a bare SPEEK membrane under the same conditions was only 4.53 mS cm(-1). PEMFCs containing SPEEK/CeO2-ATiO(2) (2 wt%) nanocomposite membrane attained a maximum power density of 117 mW cm(-2) at a load current density of 371 mA/cm(2) at 60 degrees C under 100% RH. In contrast, a PEMFC containing the bare SPEEK membrane delivered a power density of 91 mW cm(-2) at a load current of 253 mA cm(-2). A single cell open circuit voltage (OCV) test to examine the durability of membranes revealed that a PEMFC with an SPEEK/CeO2-ATiO(2) (2 wt%) membrane showed excellent stability with an OCV decay of 0.925 mV h(-1) at 60 degrees C under 30% RH, whereas that of a PEMFC with a bare SPEEK membrane was 3.437 mV h(-1) under identical conditions. Based on the abovementioned results, it is found that the SPEEK/CeO2-ATiO(2) nanocomposite membranes overcome the durability issues of pristine SPEEK membranes and show enhanced electrochemical performance under a harsh PEMFC environment. Highlights CeO2-ATiO(2) was utilized as a bifunctional filler to fabricate composite membrane. Integration of CeO2-ATiO(2) improved the proton conductivity of sulfonated poly(ether ether ketone) (SPEEK) under low relative humidity. Addition of CeO2-ATiO(2) to SPEEK resulted in improved physiochemical and thermomechanical properties. Optimized SPEEK/CeO2-ATiO(2) (2 wt%) exhibited improved proton exchange membrane fuel cell performance while retaining excellent durability compared to pristine SPEEK.FALSEsciescopu
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
Site‐selective substitution and resulting magnetism in arc‐melted perovskite ATiO₃₋δ (A = Ca, Sr, Ba)
Full text linkMagnetic properties in perovskite titanates ATiO₃₋δ (A = Ca, Sr, Ba) were investigated before and after arc melting. Crystal structure analysis was conducted by powder synchrotron X‐ray diffraction with Rietveld refinements. Quantitative chemical element analysis was carried out by X‐ray photoelectron spectroscopy. Magnetic measurements were conducted by vibrating sample magnetometer and X‐ray magnetic circular dichroism (XMCD). The magnetic properties are found to be affected by impurities of 3d elements such as Fe, Co, and Ni. Depending on the composition and crystal structure, the occupation of the magnetic ions in perovskite titanates is selectively varied, which is interpreted to be the origin of the different magnetic behaviors in arc‐melted perovskite titanates ATiO₃₋δ (A = Ca, Sr, Ba). In addition, both formation of oxygen vacancies and the reduction of Ti⁴⁺ to Ti³⁺ during arc‐melting also play a role as proven by XMCD. Nevertheless, preferential site occupation of magnetic impurities is dominant in the magnetic properties of arc‐melted perovskite ATiO₃₋δ (A = Ca, Sr, Ba)
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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