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- Gajdek, Dorotea, et al.
(författare)
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Structural Changes in Monolayer Cobalt Oxides under Ambient Pressure CO and O 2 Studied by In Situ Grazing-Incidence X-ray Absorption Fine Structure Spectroscopy
- 2022
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Ingår i: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 126:7, s. 3411-3418
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Tidskriftsartikel (refereegranskat)abstract
- We have used grazing incidence X-ray absorption fine structure spectroscopy at the cobalt K-edge to characterize monolayer CoO films on Pt(111) under ambient pressure exposure to CO and O2, with the aim of identifying the Co phases present and their transformations under oxidizing and reducing conditions. X-ray absorption near edge structure (XANES) spectra show clear changes in the chemical state of Co, with the 2+ state predominant under CO exposure and the 3+ state predominant under O2-rich conditions. Extended X-ray absorption fine structure spectroscopy (EXAFS) analysis shows that the CoO bilayer characterized in ultrahigh vacuum is not formed under the conditions used in this study. Instead, the spectra acquired at low temperatures suggest formation of cobalt hydroxide and oxyhydroxide. At higher temperatures, the spectra indicate dewetting of the film and suggest formation of bulklike Co3O4 under oxidizing conditions. The experiments demonstrate the power of hard X-ray spectroscopy to probe the structures of well-defined oxide monolayers on metal single crystals under realistic catalytic conditions.
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- Unell, Lennart, et al.
(författare)
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Dental status and self-assessed chewing ability in 70-and 80-year-old subjects in Sweden
- 2015
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Ingår i: Journal of Oral Rehabilitation. - : Wiley-Blackwell. - 1365-2842 .- 0305-182X. ; 42:9, s. 693-700
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Tidskriftsartikel (refereegranskat)abstract
- The objective was to compare two cohorts of elderly people, 70 and 80 years old, with respect to dental status and self-assessed chewing ability. The hypotheses were as follows: (i) dental status is associated with self-assessed chewing ability; (ii) chewing ability is poorer among the 80-than the 70-year-old subjects. Identical questionnaires were in 2012 sent to all subjects born in 1942 and 1932, living in two Swedish counties. The response rate was 70.1% resulting in samples of 5697 70- and 2922 80-year-old subjects. Answers to questions on self-assessed chewing ability, dental status and some other factors have been analysed. Dental status varied but was in general good; 72% of the 70- and 60% of the 80-year-old subjects reported that they had all or only few missing teeth. Rate of edentulism was 3% and 7%, respectively. Removable partial dentures were reported by 6% and 10%, respectively, implant treatment by 13% in both cohorts. Self-assessed chewing ability was mostly good and correlated with the number of teeth (Spearman rho = 0.46). A majority of the edentulous subjects assessed their chewing ability as very or fairly good. Logistic regression showed that self-assessed chewing ability was significantly associated with a number of dental variables but also with general health. In conclusion, dental status was relatively good at both ages but somewhat poorer in the older cohort. Dental status, some other dental variables and being healthy were in both age groups significantly associated with self-assessed chewing ability.
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