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The effect of postdeposition annealing on chemical bonding in amorphous carbon nitride films prepared by DC magnetron sputtering.
No full textThe effects of thermal annealing on the surface morphology, composition and chemical bond structure of amorphous carbon nitride (a-C:N) films deposited by dc magnetron sputtering are reported. Atomic force microscopy (AFM) results show that thermal annealing can gradually change the surface structure of the films from a cauliflower-like texture eventually to a uniform granular texture. Fourier transform infrared absorption (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) have been used to characterise the change of chemical bonding induced by annealing. By detailed analysis of both C 1s and N 1s photoelectron spectra, we have found that annealing can break the C---N bonds in the films and that the graphite-like C---N bonds are relatively more stable with the increase of anneal temperature
Variation of bonding structure near the surface of carbon nitride films
No full textAmorphous carbon nitride (a-C:N) films were deposited by reactive direct current magnetron sputtering of graphite using a gaseous mixture of Ar and N2. X-ray photo electron spectroscopy analysis (XPS) showed that there is an optimum volume ratio of nitrogen:argon in the sputter gas that results in a maximum content of incorporated nitrogen in the films. By using different take-off angles in XPS experiments, the variation gradient of bonding structure near the surface of a-C:N films has also been studied. In the surface layer of the a-C:N films, it was found that some of the initially formed ?-C3N4-like phase transforms to a graphite-like carbon–nitrogen phase. This structural change is driven by the nitrogen in the sputter gas during deposition
Microstructural studies of copper incorporated amorphous carbon nitride films
No full textThe effects of the incorporation of copper on the microstructure of amorphous carbon nitride films has been studied. Copper incorporated amorphous carbon nitride films (a-C : N : Cu) with different copper concentrations have been prepared by a magnetron co-sputtering technique. Both X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) have been used to characterise the bonding structures in the films. It is found that the N/(N+C) atomic ratio increases due to the incorporation of copper. The results also show that copper incorporation promotes formation of the sp3-bonded carbon nitrogen phase. The diamond nucleation in a-C : N : Cu films, which is determined from the observation of two-phonon diamond absorption FTIR bands, has been ascribed to the favorable formation of the sp3-bonded carbon nitrogen phase in the a-C : N : Cu films
Influence of rf power on carbon nitride films prepared by rf magnetron sputtering
No full textSince (beta) -C3N4 has been predicted to be a superhard material with a higher hardness than diamond, many research groups have attempted to synthesize carbon nitride materials. We have prepared amorphous carbon nitride (a-C:N) films by rf magnetron sputtering of graphite with N2 as the sputter gas. In this investigation, a series of film samples have been deposited at different rf power. AFM images have shown that the higher the rf power, the bigger the cluster size on the films and the rougher the surface of the films. By analyzing the results of our XPS experiments, we have found that with the decrease of the rf power, not only the incorporated nitrogen but also the concentration of sp3-bonded nitrogen in the films increased. We believe this is because f lower rf power results in smaller carbon clusters on the surface of the films, leading to larger carbon surface area. A larger film surface area makes it easier for the nitrogen to bond with carbon
Dealing with doubt how patients account for non-specific chronic low back pain
No full textObjective: To explore the ways that persons with long standing chronic low back pain respond to the problem of medical doubt about the presence of organic pathology.Method: Qualitative analysis of accounts provided by 12 persons attending a back pain rehabilitation clinic in NW England.Results: Subjects rejected the notion that they were culpable for their pain. They were not culpable for the onset of their pain. They argued that despite their cooperation, no sensible explanation of their pain was forthcoming from health professionals. Finally, they asserted that medical scepticism had been damaging and dispiriting.Conclusion: Patients dealt with clinical doubt by stressing their own expertise. They constituted their beliefs about the cause and trajectory of their pain and disability as accurate accounts of their disability. They resisted the suggestion that there might be psychological factors involved in their ill-health by locating culpability among clinicians, who were confused or uncertain about diagnosis and treatment.<br/
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
Microstructural properties of amorphous carbon nitride films synthesized by dc magnetron sputtering.
No full textAmorphous carbon nitride (a-C:N) films have been prepared on silicon(1 0 0) substrates by direct current magnetron sputtering of graphite using a gaseous mixture of Ar and N2. Raman spectra have shown that these a-C:N films have a graphitic structure. The incorporation of nitrogen in the films has been confirmed by Fourier transform infrared (FTIR) spectroscopy. Graphitic and disordered sp2-bonded carbon which are present in Raman spectra and are normally forbidden (not observed) in FTIR become infrared active in our films as the symmetry of the hexagonal carbon rings is broken by nitrogen incorporation. X-ray photoelectron spectroscopy has been used to study the type of chemical bonding in these a-C:N films. The C 1s and N 1s X-ray photoelectron peaks have been deconvoluted and studied. We have found that for the C6-point triple bond; length half of m-dashN and C=N components of the C 1s and N 1s photoelectron peaks, there is a maximum peak intensity ratio of C6-point triple bond; length half of m-dashN:C=N in the films deposited when the gaseous mixture contains 35% N2 in the sputter gas
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