| 1. |
- Andersson, Lars M, et al.
(författare)
-
En man med många talanger
- 2002
-
Ingår i: På historiens slagfält. En festskrift tillägnad Sverker Oredsson. - Uppsala : Sisyfos. - 9163131048 ; , s. 19-23
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 2. |
|
|
| 3. |
- Wingbrant, Helena, et al.
(författare)
-
MISiCFET chemical sensors for applications in exhaust gases and flue gases
- 2002
-
Ingår i: Materials Science Forum. - 0255-5476 .- 1662-9752. ; 433-4, s. 953-956
-
Tidskriftsartikel (refereegranskat)abstract
- A chemical gas sensor based on a silicon carbide field effect transistor with a catalytic gate metal has been under development for a number of years. The choice of silicon carbide as the semiconductor material allows the sensor to operate at high temperatures, for more than 6 months in flue gases at 300degreesC and for at least three days at 700degreesC. The chemical inertness of silicon carbide and a buried gate design makes it a suitable sensor technology for applications in corrosive environments such as exhaust gases and flue gases from boilers. The selectivity of the sensor devices is established through the choice of type and structure of the gate metal as well as the operation temperature. In this way NH3 sensors with low cross sensitivity to NOx have been demonstrated as potential sensors for control of selective catalytic reduction (SCR) of NOx by urea injection into diesel exhausts. Here we show that sensors with a porous platinum or iridium gate show different temperature ranges for NH3 detection. The hardness of the silicon carbide makes it for example more resistant to water splash at cold start of a petrol engine than existing technologies, and a sensor which can control the air to fuel ratio, before the exhaust gases are heated, has been demonstrated. Silicon carbide sensors are also tested in flue gases from boilers. Efficient regulation of the combustion in a boiler will decrease fuel consumption and reduce emissions.
|
|
| 4. |
|
|
| 5. |
- Assarsson, Maria, et al.
(författare)
-
Restoring proper radical generation by azide binding to the iron site of the E238A mutant R2 protein of ribonucleotide reductase from Escherichia coli.
- 2001
-
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 276:29, s. 26852-26859
-
Tidskriftsartikel (refereegranskat)abstract
- The enzyme activity of Escherichia coli ribonucleotide reductase requires the presence of a stable tyrosyl free radical and diiron center in its smaller R2 component. The iron/radical site is formed in a reconstitution reaction between ferrous iron and molecular oxygen in the protein. The reaction is known to proceed via a paramagnetic intermediate X, formally a Fe(III)-Fe(IV) state. We have used 9.6 GHz and 285 GHz EPR to investigate intermediates in the reconstitution reaction in the iron ligand mutant R2 E238A with or without azide, formate, or acetate present. Paramagnetic intermediates, i.e. a long-living X-like intermediate and a transient tyrosyl radical, were observed only with azide and under none of the other conditions. A crystal structure of the mutant protein R2 E238A/Y122F with a diferrous iron site complexed with azide was determined. Azide was found to be a bridging ligand and the absent Glu-238 ligand was compensated for by azide and an extra coordination from Glu-204. A general scheme for the reconstitution reaction is presented based on EPR and structure results. This indicates that tyrosyl radical generation requires a specific ligand coordination with 4-coordinate Fe1 and 6-coordinate Fe2 after oxygen binding to the diferrous site.
|
|
| 6. |
|
|
| 7. |
- Erjefält, Jonas, et al.
(författare)
-
Cytolysis and piecemeal degranulation as distinct modes of activation of airway mucosal eosinophils
- 1998
-
Ingår i: Journal of Allergy and Clinical Immunology. - 1097-6825. ; 102:2, s. 286-294
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cytotoxic eosinophil granule proteins are considered important in the pathogenesis of inflammatory airway diseases, including asthma, rhinitis, and polyposis. However, little is known about the mechanisms involved in the deposition of these tissue-damaging granular products in vivo. OBJECTIVE: We sought to determine the occurrence of degranulating eosinophils, those with morphologic evidence of cytolysis with associated clusters of free eosinophil granules (Cfegs), and to identify the frequency of apoptotic eosinophils in inflamed upper airway tissue. METHODS: Eosinophil-rich nasal polyps were processed for transmission electron microscopy and for light microscopic evaluation of whole-mount preparations subjected to deep tissue staining for eosinophil peroxidase. RESULTS: The mean proportion of eosinophil subtypes were intact and resting (6.8%), intact but degranulating (83%), cytolytic or Cfegs (9.9%), and apoptotic (0.0%). All degranulating eosinophils exhibited piecemeal degranulation. The occurrence of Cfegs was confirmed in nonsectioned whole-mount preparations. Depending on the appearance of their core and matrix, the specific granules were divided into four subtypes, and a degranulation index (altered per total granules) was calculated for each eosinophil. Cytolytic eosinophils had a much lower degranulation index than intact eosinophils present in the same tissue (P < .001). CONCLUSIONS: These data indicate that eosinophil cytolysis is present in human airway mucosa, that its occurrence is not an artifact of the means of tissue handling, and that cytolysis of eosinophils may occur without prior extensive degranulation. We suggest that eosinophil cytolysis is a major activation mechanism, which occurs along with, but is distinct from, other types of degranulation.
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
