1,720,959 research outputs found
XPS investigation of F-doped MnO2 nanosystems fabricated by plasma assisted-CVD
No full textSupported Mn(IV) oxide nanomaterials were prepared by plasma assisted-chemical vapor deposition
from Ar/O2 plasmas starting from a fluorinated Mn(II) β-diketonate diamine adduct. Under the
adopted conditions, the target compound served as a single-source molecular precursor for the
obtainment of MnO2 nanosystems uniformly doped with fluorine. The overall F content in the target
materials, composed of phase-pure β-MnO2, could be tailored as a function of the deposition temperature
from 100 to 400 °C, a result of particular importance in view of photocatalytic and gas sensing
applications. In the present study, attention is specifically devoted to the investigation of a representative
specimen by means of x-ray photoelectron spectroscopy. Besides the wide scan spectrum, a
detailed analysis of C 1s, O 1s, Mn 2p, Mn 3s, and F 1s photoelectron peaks is presented and discussed.
The analyses reveal the formation of MnO2 free from other manganese oxides, with fluorine
present in different chemical states, i.e., lattice F plus traces of precursor residuals at the system
surface
Plasma-Assisted Growth of β-MnO2 Nanosystems as Gas Sensors for Safety and Food Industry Applications
Full text linkThe development of efficient sensors for security field and food quality control applications has gained an ever-increasing attention for various end-uses. In this context, this work reports on the preparation of β-MnO2 nanosystems by plasma enhanced-chemical vapor deposition (PE-CVD), using a fluorinated Mn(II) diamine-diketonate as single-source precursor for both Mn and F. Modulations
of oxygen partial pressure enable to tailor not only the morphology and oxygen vacancy content, but also fluorine doping level of the resulting systems. For the first time, the gas sensing performances of PE-CVD β-MnO2 nanomaterials are tested in the detection of acetonitrile, a poisonous chemical warfare agent (CWA) simulant, and ethylene, an important marker of fruit ripening. The obtained results demonstrate that the fabricated sensors can efficiently detect these analytes, with the best responses at moderate temperatures (≤200 °C), enhanced by a higher oxygen vacancy content and fluorine concentration. These features, coupled with the good selectivity and response times, candidate the developed systems as amenable platforms for practical applications
Insights into the Plasma-Assisted Fabrication and Nanoscopic Investigation of Tailored MnO2 Nanomaterials
Full text linkAmong transition metal oxides, MnO2 is of considerable importance for various technological end-uses, from heterogeneous catalysis to gas sensing, owing to its structural flexibility and unique properties at the nanoscale. In this work, we demonstrate the successful fabrication of supported MnO2 nanomaterials by a catalyst-free, plasma-assisted process starting from a fluorinated manganese(II) molecular source in Ar/O2 plasmas. A thorough multitechnique characterization aimed at the systematic investigation of material structure, chemical composition, and morphology revealed the formation of F-doped, oxygen-deficient, MnO2-based nanomaterials, with a fluorine content tunable as a function of growth temperature (TG). Whereas phase-pure β-MnO2 was obtained for 100 °C ≤ TG ≤ 300 °C, the formation of mixed phase MnO2 + Mn2O3 nanosystems took place at 400 °C. In addition, the system nano-organization could be finely tailored, resulting in a controllable evolution from wheat-ear columnar arrays to high aspect ratio pointed-tip nanorod assemblies. Concomitantly, magnetic force microscopy analyses suggested the formation of spin domains with features dependent on material morphology. Preliminary tests in Vis-light activated photocatalytic degradation of rhodamine B aqueous solutions pave the way to possible applications of the target materials in wastewater purification
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
