| 1. |
- Boija, Elisabet, et al.
(författare)
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Bilayer disk capillary electrophoresis : a novel method to study drug partitioning into membranes
- 2008
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Ingår i: Electrophoresis. - : Wiley. - 0173-0835 .- 1522-2683. ; 29:16, s. 3377-3383
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Tidskriftsartikel (refereegranskat)abstract
- CE in the presence of lipid bilayer disks was introduced as a new approach in membrane partitioning studies. The disks were used as a pseudostationary phase in the partial-filling mode of CE and the partitioning of cationic drugs was determined. The migration times of the analytes increased linearly with the lipid amount in the system. An appropriate algorithm for the calculation of a partition coefficient is presented. In the disk-shaped bilayers, which have excellent stability and shelf life, all of the lipids are readily available for interaction and the disks can be used as realistic cell membrane models.
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| 2. |
- Canovic, Sead, et al.
(författare)
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Microstructural investigation of the initial oxidation of the FeCrAlRE alloy Kanthal AF in dry and wet O2 at 600 and 800°C
- 2010
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Ingår i: Journal of the Electrochemical Society. - : The electrochemical society. - 0013-4651 .- 1945-7111. ; 157:6, s. C223-C230
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Tidskriftsartikel (refereegranskat)abstract
- The FeCrAlRE (where RE is reactive element) alloy Kanthal AF was exposed isothermally at 600 and 800°C for 72 h in dry O2 and in O2 with 10 vol % H2O. The mass gains were 3–5 times higher at the higher temperature. The presence of water vapor increased the oxidation rate at 800°C, while no significant effect was observed at 600°C. A thin two-layered oxide formed at 600°C: an outer (Fe,Cr)2O3 corundum-type oxide, containing some Al, and an inner, probably amorphous, Al-rich oxide. At 800°C a two-layered oxide formed in both environments. The inner layer consisted of inward grown a-Al2O3. In dry O2 the originally formed outward grown g-Al2O3 had transformed to a-Al2O3 after 72 h. Water vapor stabilized the outward grown g-Al2O3 and hence no transformation occurred after 72 h in humid environment. RE-rich oxide particles with varying composition (Y, Zr, and Ti) were distributed in the base oxide at both temperatures and in both environments. The RE-rich particles were separated from the alloy substrate by a layer of Al-rich oxide. At 800°C the Y-rich RE particles were surrounded by thick oxide patches in both dry and humid O2.
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| 4. |
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| 5. |
- Engkvist, Josefin, 1972, et al.
(författare)
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Alumina scale formation on a powder metallurgical FeCrAl alloy (Kanthal APMT) at 900-1100°C in dry O2 and in O2 + H2O
- 2010
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Ingår i: Oxidation of Metals. - : Springer Science and Business Media LLC. - 1573-4889 .- 0030-770X. ; 73:1, s. 233-253
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Tidskriftsartikel (refereegranskat)abstract
- A Rapidly Solidified Powder (RSP) metallurgical FeCrAl alloy, Kanthal APMT, was exposed in dry and humid O-2 for 72 h at 900-1,100 A degrees C. The formed oxide scales were characterized using gravimetry in combination with advanced analysis techniques (SEM, EDX, TEM, XRD, AES and SIMS). The oxide scales were at all exposures composed of two-layered alpha-Al2O3 scales exhibiting a top layer of equiaxed grains and a bottom layer containing elongated grains. A Cr-rich zone, originating in the native oxide present before exposure, separated these two layers. The top alpha-Al2O3 layer is suggested to have formed by transformation of outwardly grown metastable alumina, while the inward-grown bottom alpha-Al2O3 layer had incorporated small Zr-, Hf- and Ti-rich oxide particles present in the alloy matrix. The scale also contained larger Y-rich oxide particles. Furthermore, in the temperature range studied, the presence of water vapour accelerated alloy oxidation somewhat and affected scale morphology.
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| 6. |
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| 7. |
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| 8. |
- Engkvist, Josefin, 1972, et al.
(författare)
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Oxidation of FeCrAl foils at 500-900 degrees C in dry O-2 and O-2 with 40% H2O
- 2009
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Ingår i: Materials at High Temperatures. - 0960-3409 .- 1878-6413. ; 26:2, s. 199-210
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Tidskriftsartikel (refereegranskat)abstract
- High temperature resistant FeCrAl alloys are frequently used in high temperature applications Such as heating elements and metal based catalytic converter bodies. When exposed to high temperatures an adherent, slowly growing, dense aluminium oxide layer forms on the surface, which protects the underlying alloy from severe degradation. The composition, structure and properties of the formed oxide layer are strongly dependent on the alloy composition, temperature and oxidation environment. In this study, the Sandvik 0C404 FeCrAl alloy, in the form of 50 mu m thick foils, was exposed isothermally in the temperature range 500-900 degrees C for 168 hours in dry O-2 and in O-2 with 40 vol.% H2O. The surface morphology, composition and microstructure of the grown oxide scales were characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), grazing incidence X-ray diffraction (GI-XRD), Auger electron spectroscopy (AES), and time of flight secondary ion mass spectrometry (TOF-SIMS). The oxidation process was faster at 900 degrees C than at 500 and 700 degrees C. At 500 degrees C a thin (10-20 nm) mixed oxide of Fe, Cr and Al was formed. Exposure at 700 degrees C resulted ill a similar (40-50 nm) duplex oxide, in both dry O-2 and in O-2 With 40 vol.% H2O. These oxide scales consisted of all inner and an outer relatively pure alumina separated by a Cr-rich band. This type of duplex oxide scale also formed at 900 degrees C with a thin inward growing alpha-Al2O3 at the oxide/metal interface and an outward growing layer outside a Cr-rich band. However, at 900 degrees C the Outward growing layer showed two types of oxide morphologies; a thin smooth base oxide and a much thicker nodular oxide grown on top of substrate ridges. In dry O-2 atmosphere, the main part of this outward growing layer had transformed to alpha-Al2O3. Only in the outer part of the thick oxide nodules, metastable alumina was found. When exposed in the presence of water vapour the main pall of the metastable alumina remained untransformed.
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| 9. |
- Haataja, Topi, et al.
(författare)
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Enzyme kinetics by GH7 cellobiohydrolases on chromogenic substrates is dictated by non-productive binding : insights from crystal structures and MD simulation
- 2023
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Ingår i: The FEBS Journal. - : John Wiley & Sons. - 1742-464X .- 1742-4658. ; 290:2, s. 379-399
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Tidskriftsartikel (refereegranskat)abstract
- Cellobiohydrolases (CBHs) in the glycoside hydrolase family 7 (GH7) (EC3.2.1.176) are the major cellulose degrading enzymes both in industrial settings and in the context of carbon cycling in nature. Small carbohydrate conjugates such as p-nitrophenyl-beta-d-cellobioside (pNPC), p-nitrophenyl-beta-d-lactoside (pNPL) and methylumbelliferyl-beta-d-cellobioside have commonly been used in colorimetric and fluorometric assays for analysing activity of these enzymes. Despite the similar nature of these compounds the kinetics of their enzymatic hydrolysis vary greatly between the different compounds as well as among different enzymes within the GH7 family. Through enzyme kinetics, crystallographic structure determination, molecular dynamics simulations, and fluorometric binding studies using the closely related compound o-nitrophenyl-beta-d-cellobioside (oNPC), in this work we examine the different hydrolysis characteristics of these compounds on two model enzymes of this class, TrCel7A from Trichoderma reesei and PcCel7D from Phanerochaete chrysosporium. Protein crystal structures of the E212Q mutant of TrCel7A with pNPC and pNPL, and the wildtype TrCel7A with oNPC, reveal that non-productive binding at the product site is the dominating binding mode for these compounds. Enzyme kinetics results suggest the strength of non-productive binding is a key determinant for the activity characteristics on these substrates, with PcCel7D consistently showing higher turnover rates (k(cat)) than TrCel7A, but higher Michaelis-Menten (K-M) constants as well. Furthermore, oNPC turned out to be useful as an active-site probe for fluorometric determination of the dissociation constant for cellobiose on TrCel7A but could not be utilized for the same purpose on PcCel7D, likely due to strong binding to an unknown site outside the active site.
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| 10. |
- Hasselgren, Mikael, 1964-
(författare)
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Epidemiological Aspects of Asthma in Primary Care : Special Reference to Prevalence, Clinical Detection and Validation
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Objectives. To describe the prevalence of asthma in a mid-Swedish region and measure the detection rate of asthma in primary care. To compare clinical outcomes for adolescents with asthma in primary care or in paediatric care and to perform a clinical validation in children with airway, nose and skin symptoms. Material and methods. A questionnaire survey of respiratory symptoms and disease in an adult population and an investigation of the occurrence of clinically detected asthma in primary care. A cross-sectional study comparing management, asthma control and quality of life in adolescents. The last study was a nested case-control study with a clinical validation of reported allergic symptoms in children. Results. The prevalence of asthma in the adult population was 8%. The clinical prevalence of asthma in primary care was 2%. The detection rate was higher in primary health care centres with asthma clinics, as compared to primary care without such clinics. In adolescents with asthma there was no difference in clinical outcomes between primary care and paediatric care. The validation study showed a high correlation between assigned cases and disease. Conclusions. Asthma is a common disease where the majority of cases are managed in primary care. Many cases are, however, not diagnosed and the detection rate becomes a quality care indicator. The study of adolescents confirms that proactive care can be further improved regardless of whether their management is in primary or paediatric care. The nested case-control design is suitable to suggest causational risk factors for asthma and for prediction of allergic disease development.
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