| 1. |
- Ueda, K., et al.
(författare)
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Adsorption and Reaction of CO and NO on Ir(111) under Near Ambient Pressure Conditions
- 2016
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Ingår i: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 59:5-7, s. 487-496
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption and reaction of CO and NO on Ir(111) have been studied by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) together with low-energy electron diffraction, scanning tunneling microscopy, and mass spectroscopy (MS). Under both ultrahigh vacuum (UHV) and NAP conditions CO molecules occupy on-top sites of the Ir(111) surface at room temperature (RT) by forming two-dimensional clusters. Exposure to NO under UHV conditions at RT induces partially dissociative adsorption, while NAP NO exposure leads to a Ir(111) surface that is covered by molecular NO. We conducted in-operando NAP-XPS/MS observation of the NO + 13CO reaction under a NAP condition as a function of temperature. Below 210 °C adsorption of NO is inhibited by CO, while above 210 °C the CO inhibition is released due to partial desorption of CO and dissociative adsorption of NO starts to occur leading to associative formation of N2. Under the most active condition studied here the Ir surface is covered by a dense co-adsorption layer consisting of on-top CO, atomic N and O, which suggests that this reaction is not a NO-dissociation-limited process but a N2/CO2 formation-limited process.
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| 2. |
- Vang, Ronnie T., et al.
(författare)
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Ethylene dissociation on flat and stepped Ni(111): A combined STM and DFT study
- 2006
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 600, s. 66-77
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Tidskriftsartikel (refereegranskat)abstract
- The dissociative adsorption of ethylene (C2H4) on Ni(1 1 1) was studied by scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The STM studies reveal that ethylene decomposes exclusively at the step edges at room temperature. However, the step edge sites are poisoned by the reaction products and thus only a small brim of decomposed ethylene is formed. At 500 K decomposition on the (1 1 1) facets leads to a continuous growth of carbidic islands, which nucleate along the step edges. DFT calculations were performed for several intermediate steps in the decomposition of ethylene on both Ni(1 1 1) and the stepped Ni(2 1 1) surface. In general the Ni(2 1 1) surface is found to have a higher reactivity than the Ni(1 1 1) surface. Furthermore, the calculations show that the influence of step edge atoms is very different for the different reaction pathways. In particular the barrier for dissociation is lowered significantly more than the barrier for dehydrogenation, and this is of great importance for the bond-breaking selectivity of Ni surfaces. The influence of step edges was also probed by evaporating Ag onto the Ni(1 1 1) surface. STM shows that the room temperature evaporation leads to a step flow growth of Ag islands, and a subsequent annealing at 800 K causes the Ag atoms to completely wet the step edges of Ni(1 1 1). The blocking of the step edges is shown to prevent all decomposition of ethylene at room temperature, whereas the terrace site decomposition at 500 K is confirmed to be unaffected by the Ag atoms. Finally a high surface area NiAg alloy catalyst supported on MgAl2O4 was synthesized and tested in flow reactor measurements. The NiAg catalyst has a much lower activity for ethane hydrogenolysis than a similar Ni catalyst, which can be rationalized by the STM and DFT results.
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| 3. |
- Chaudhary, Shilpi, et al.
(författare)
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Adsorption of 3-(triethoxysilyl)propionitrile on a rutile TiO2(110) surface : An X-ray photoelectron spectroscopy study
- 2020
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Ingår i: DAE Solid State Physics Symposium 2019. - : AIP Publishing. - 1551-7616 .- 0094-243X. - 9780735420250 ; 2265
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Konferensbidrag (refereegranskat)abstract
- The adsorption of 3-(triethoxysilyl)propionitrile (TESP) on a reduced rutile TiO2(110) surface has been investigated using synchrotron-based X-ray photoelectron spectroscopy in ultrahigh vacuum (UHV). We have studied TESP adsorption on two surface preparation of rutile TiO2 (110) to explore the role of surface defects. In the first preparation, the adsorption of TESP was studied on reduced TiO2 (110) surface at room temperature. In the second experiment TESP was adsorbed on the oxygen-treated TiO2 surface to quench the oxygen vacancies generated by UHVannealing of the TiO2 crystal. The molecular footprints of the TESP molecules confirms the adsorption on both types of TiO2(110) surfaces. In the case of the reduced surface, temperature-dependent XPS measurements show the thermal stability of TESP molecules up to 600 °C. The comparison of the nitrogen and carbon lineshapes for both preparations suggests different adsorption geometries on the reduced and oxygen-dosed surfaces. To the best of our knowledge, the UHV preparations and measurements of TESP adsorption on rutile TiO2 (110) in the present study are reported for the first time.
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| 4. |
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| 6. |
- Muraro, Antonella, et al.
(författare)
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Managing food allergy: GA2LEN guideline 2022.
- 2022
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Ingår i: The World Allergy Organization journal. - : Elsevier BV. - 1939-4551. ; 15:9
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Tidskriftsartikel (refereegranskat)abstract
- Food allergy affects approximately 2-4% of children and adults. This guideline provides recommendations for managing food allergy from the Global Allergy and Asthma European Network (GA2LEN). A multidisciplinary international Task Force developed the guideline using the Appraisal of Guidelines for Research and Evaluation (AGREE) II framework and the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. We reviewed the latest available evidence as of April 2021 (161 studies) and created recommendations by balancing benefits, harms, feasibility, and patient and clinician experiences. We suggest that people diagnosed with food allergy avoid triggering allergens (low certainty evidence). We suggest that infants with cow's milk allergy who need a breastmilk alternative use either hypoallergenic extensively hydrolyzed cow's milk formula or an amino acid-based formula (moderate certainty). For selected children with peanut allergy, we recommend oral immunotherapy (high certainty), though epicutaneous immunotherapy might be considered depending on individual preferences and availability (moderate certainty). We suggest considering oral immunotherapy for children with persistent severe hen's egg or cow's milk allergy (moderate certainty). There are significant gaps in evidence about safety and effectiveness of the various strategies. Research is needed to determine the best approaches to education, how to predict the risk of severe reactions, whether immunotherapy is cost-effective and whether biological therapies are effective alone or combined with allergen immunotherapy.
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| 7. |
- O'Shea, J. N., et al.
(författare)
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Hydrogen-bond induced surface core-level shift in isonicotinic acid
- 2001
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1089-5647 .- 1520-6106 .- 1520-5207. ; 105:10, s. 1917-1920
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Tidskriftsartikel (refereegranskat)abstract
- Intermolecular hydrogen-bonding in thick films of isonicotinic acid evaporated onto rutile TiO2(110) has been investigated with X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The rate of deposition is found to be a key factor in overcoming the kinetic barriers to extensive hydrogen-bond formation, which, when present, gives rise to large energy shifts between bulk and surface in both the N1s XPS and XAS. The origin of the surface core-level shift is attributed to the presence of non-hydrogen-bonded nitrogen atoms in the surface layer.
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