| 1. |
- Hulva, Jan, et al.
(författare)
-
Adsorption of CO on the Fe3O4(001) Surface
- 2018
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:2, s. 721-729
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction of CO with the Fe3O4(001)-(√2 × √2)R45° surface was studied using temperature-programmed desorption (TPD), scanning tunneling microscopy (STM), and X-ray photoelectron spectroscopy (XPS), the latter both under ultrahigh vacuum (UHV) conditions and in CO pressures up to 1 mbar. In general, the CO-Fe3O4 interaction is found to be weak. The strongest adsorption occurs at surface defects, leading to small TPD peaks at 115, 130, and 190 K. Desorption from the regular surface occurs in two distinct regimes. For coverages up to two CO molecules per (√2 × √2)R45° unit cell, the desorption maximum shows a large shift with increasing coverage, from initially 105 to 70 K. For coverages between 2 and 4 molecules per (√2 × √2)R45° unit cell, a much sharper desorption feature emerges at ∼65 K. Thermodynamic analysis of the TPD data suggests a phase transition from a dilute 2D gas into an ordered overlayer with CO molecules bound to surface Fe3+ sites. XPS data acquired at 45 K in UHV are consistent with physisorption. Some carbon-containing species are observed in the near-ambient-pressure XPS experiments at room temperature but are attributed to contamination and/or reaction with CO with water from the residual gas. No evidence was found for surface reduction or carburization by CO molecules.
|
|
| 2. |
- Manousek, Jan, et al.
(författare)
-
Hypersensitivity to material and environmental burden as a possible cause of late complications of cardiac implantable electronic devices
- 2018
-
Ingår i: Europace. - : Oxford University Press (OUP). - 1099-5129 .- 1532-2092. ; 20:9, s. e140-e147
-
Tidskriftsartikel (refereegranskat)abstract
- AimsTo evaluate whether patients with late complications of pacemakers or implantable cardioverter-defibrillators have hypersensitivity reactions to some of the materials used in generators or in electrodes, or to environmental metal burden.Methods and resultsThe cohort consisted of 20 men and 4 women (mean age: 62.3 +/- 17.2 years) who had a history of late complications of implanted devices. The control group involved 25 men and 8 women (mean age: 64.6 +/- 14.0 years) who had comparable devices, but no history of late complications. Lymphocyte transformation test was used to evaluate hypersensitivity to eight metal pollutants (antimony, manganese, mercury, molybdenum, nickel, platinum, tin, and titanium) selected by results of questionnaires on environmental burden, and by material analysis of generators and electrode surfaces. Exposures to metal pollutants were approximately the same in patients and in controls. Titanium alloy used in generators contained at least 99.32% of titanium and trace levels of other metals; higher levels of tin and platinum were detected in electrode surfaces. Hypersensitivity reactions to mercury and tin were significantly more frequent in patients than in controls (patients and controls: mercury: 68.2 and 31.1%, respectively; P = 0.022; tin: 25.0 and 3.2%, respectively; P = 0.035). In contrast, hypersensitivity to manganese was significantly more frequent in controls than in patients (patients and controls: 13.6 and 50.0%, respectively; P = 0.008).ConclusionOur findings suggest a possible relation between hypersensitivity to metals used in implantable devices or to environmental metal burden and the occurrence of their late complications.
|
|
| 3. |
- Volf, Martin, et al.
(författare)
-
Community structure of insect herbivores is driven by conservatism, escalation and divergence of defensive traits in Ficus
- 2018
-
Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 21:1, s. 83-92
-
Tidskriftsartikel (refereegranskat)abstract
- Escalation (macroevolutionary increase) or divergence (disparity between relatives) in trait values are two frequent outcomes of the plant-herbivore arms race. We studied the defences and caterpillars associated with 21 sympatric New Guinean figs. Herbivore generalists were concentrated on hosts with low protease and oxidative activity. The distribution of specialists correlated with phylogeny, protease and trichomes. Additionally, highly specialised Asota moths used alkaloid rich plants. The evolution of proteases was conserved, alkaloid diversity has escalated across the studied species, oxidative activity has escalated within one clade, and trichomes have diverged across the phylogeny. Herbivore specificity correlated with their response to host defences: escalating traits largely affected generalists and divergent traits specialists; but the effect of escalating traits on extreme specialists was positive. In turn, the evolution of defences in Ficus can be driven towards both escalation and divergence in individual traits, in combination providing protection against a broad spectrum of herbivores.
|
|
