| 1. |
|
|
| 2. |
- Abrahamsson, M. L. A., et al.
(författare)
-
Ruthenium-manganese complexes for artificial photosynthesis : Factors controlling intramolecular electron transfer and excited-state quenching reactions
- 2002
-
Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 41:6, s. 1534-1544
-
Tidskriftsartikel (refereegranskat)abstract
- Continuing our work toward a system mimicking the electron-transfer steps from manganese to P-680(+) in photosystem II (PS II), we report a series of ruthenium(II)-manganese(II) complexes that display intramolecular electron transfer from manganese(II) to photooxidized ruthenium(III). The electron-transfer rate constant (k(ET)) values span a large range, 1 X 10(5)-2 x 10(7) s(-1), and we have investigated different factors that are responsible for the variation. The reorganization energies determined experimentally (lambda = 1.5-2.0 eV) are larger than expected for solvent reorganization in complexes of similar size in polar solvents (typically lambda approximate to 1.0 eV). This result indicates that the inner reorganization energy is relatively large and, consequently, that at moderate driving force values manganese complexes are not fast donors. Both the type of manganese ligand and the link between the two metals are shown to be of great importance to the electron-transfer rate. In contrast, we show that the quenching of the excited state of the ruthenium(II) moiety by manganese(II) in this series of complexes mainly depends on the distance between the metals. However, by synthetically modifying the sensitizer so that the lowest metal-to-ligand charge transfer state was localized on the nonbridging ruthenium(II) ligands, we could reduce the quenching rate constant in one complex by a factor of 700 without changing the bridging ligand. Still, the manganese(II)-ruthenium (III) electrontransfer rate constant was not reduced. Consequently, the modification resulted in a complex with very favorable properties.
|
|
| 3. |
|
|
| 4. |
- Adsten, M, et al.
(författare)
-
Measurement of radiation distribution on the absorber in an asymmetric CPC collector
- 2004
-
Ingår i: Solar Energy. - : Elsevier BV. - 0038-092X .- 1471-1257. ; 76:1-3, s. 199-206
-
Tidskriftsartikel (refereegranskat)abstract
- A method to estimate the annual collected energy and the annual average optical efficiency factor is suggested. The radiation distribution on the absorber of an asymmetric CPC collector with a flat bi-facial absorber is measured for three different absorber mounting angles using a photo diode. The annual optical efficiency factors and a relative measure of the annual collected energy are determined for collectors with the absorber fin thickness 0.5 and 1 mm, and for a collector with a teflon convection suppression film mounted around the absorber. With the local optical efficiency factors and the annual incident solar energy distribution considered, the analysis indicates that the energy gain for a mounting angle of 20 is higher than for a collector with 65 absorber mounting angle. The annual collected energy is increased with 6-8% if the absorber fin thickness is increased from 0.5 to 1 mm. The annual average optical efficiency factor is relatively independent of the absorber mounting angle. It was found to be 0.87-0.88 for a collector with a 0.5 mm thick absorber fin and 0.92 for a collector with a 1 mm thick absorber fin or for a collector with 0.5 mm thick absorber fin with a teflon convection suppression film added. The low annual average optical efficiency factor is not caused by the uneven irradiance distribution but by the relatively high U-L-values. (C) 2003 Elsevier Ltd. All rights reserved.
|
|
| 5. |
|
|
| 6. |
- Ahrén, Bo, et al.
(författare)
-
Inhibition of dipeptidyl peptidase IV improves metabolic control over a 4-week study period in type 2 diabetes.
- 2002
-
Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 25:5, s. 869-75
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Glucagon-like peptide-1 (GLP-1) has been proposed as a new treatment modality for type 2 diabetes. To circumvent the drawback of the short half-life of GLP-1, inhibitors of the GLP-1-degrading enzyme dipeptidyl peptidase IV (DPP IV) have been examined. Such inhibitors improve glucose tolerance in insulin-resistant rats and mice. In this study, we examined the 4-week effect of 1-[[[2-[(5-cyanopyridin-2-yl)amino]ethyl]amino]acetyl]-2-cyano-(S)-pyrrolidine (NVP DPP728), a selective, orally active inhibitor of DPP IV, in subjects with diet-controlled type 2 diabetes in a placebo-controlled double-blind multicenter study.RESEARCH DESIGN AND METHODS: A total of 93 patients (61 men and 32 women), aged 64 +/- 9 years (means +/- SD) and with BMI 27.3 +/- 2.7 kg/m(2), entered the study. Fasting blood glucose was 8.5 +/- 1.5 mmol/l, and HbA(1c) was 7.4 +/- 0.7%. Before and after treatment with NVP DPP728 at 100 mg x 3 (n = 31) or 150 mg x 5 (n = 32) or placebo (n = 30), subjects underwent a 24-h study with standardized meals (total 2,000 kcal).RESULTS: Compared with placebo, NVP DPP728 at 100 mg t.i.d. reduced fasting glucose by 1.0 mmol/l (mean), prandial glucose excursions by 1.2 mmol/l, and mean 24-h glucose levels by 1.0 mmol/l (all P < 0.001). Similar reductions were seen in the 150-mg b.i.d. treatment group. Mean 24-h insulin was reduced by 26 pmol/l in both groups (P = 0.017 and P = 0.023). Although not an efficacy parameter foreseen in the study protocol, HbA(1c) was reduced to 6.9 +/- 0.7% in the combined active treatment groups (P < 0.001). Laboratory safety and tolerability was good in all groups.CONCLUSIONS: We conclude that inhibition of DPP IV is a feasible approach to the treatment of type 2 diabetes in the early stage of the disease.
|
|
| 7. |
- Ajitha, D, et al.
(författare)
-
Spin-orbit ab initio study of alkyl halide dissociation via electronic curve crossing
- 2004
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 121:12, s. 5761-5766
-
Tidskriftsartikel (refereegranskat)abstract
- An ab initio study of the role of electronic curve crossing in the photodissociation dynamics of the alkyl halides is presented. Recent experimental studies show that curve crossing plays a deterministic role in deciding the channel of dissociation. Coupled repulsive potential energy curves of the low-lying n-sigma* states are studied including spin-orbit and relativistic effects. Basis set including effect of core correlation is used. Ab initio vertical excitation spectra of CH3I and CF3I are in agreement with the experimental observation. The curve crossing region is around 2.371 Angstrom for CH3I and CF3I. The potential curves of the repulsive excited states have larger slope for CF3I, suggesting a higher velocity and decreased intersystem crossing probability on fluorination. We also report the potential curves and the region of curve crossing for CH3Br and CH3Cl.
|
|
| 8. |
- Alm, Per A
(författare)
-
Stuttering, emotions, and heart rate during anticipatory anxiety: a critical review.
- 2004
-
Ingår i: Journal of Fluency Disorders. - : Elsevier BV. - 1873-801X .- 0094-730X. ; 29:2, s. 123-133
-
Tidskriftsartikel (refereegranskat)abstract
- Persons who stutter often report their stuttering is influenced by emotional reactions, yet the nature of such relation is still unclear. Psychophysiological studies of stuttering have failed to find any major association between stuttering and the activity of the sympathetic nervous system. A review of published studies of heart rate in relation to stressful speech situations indicate that adults who stutter tend to show a paradoxical reduction of heart rate compared with nonstuttering persons. Reduction of heart rate has also been observed in humans and mammals during anticipation of an unpleasant stimulus, and is proposed to be an indication of anticipatory anxiety resulting in a “freezing response” with parasympathetic inhibition of the heart rate. It is suggested that speech-related anticipatory anxiety in persons who stutter is likely to be a secondary, conditioned reaction based on previous experiences of stuttering.
|
|
| 9. |
- Alvarado-Kristensson, Maria, et al.
(författare)
-
p38-MAPK signals survival by phosphorylation of caspase-8 and caspase-3 in human neutrophils
- 2004
-
Ingår i: Journal of Experimental Medicine. - : Rockefeller University Press. - 0022-1007 .- 1540-9538. ; 199:4, s. 449-458
-
Tidskriftsartikel (refereegranskat)abstract
- Neutrophil apoptosis occurs both in the bloodstream and in the tissue and is considered essential for the resolution of an inflammatory process. Here, we show that p38-mitogen-activated protein kinase (MAPK) associates to caspase-8 and caspase-3 during neutrophil apoptosis and that p38-MAPK activity, previously shown to be a survival signal in these primary cells, correlates with the levels of caspase-8 and caspase-3 phosphorylation. In in vitro experiments, immunoprecipitated active p38-MAPK phosphorylated and inhibited the activity of the active p20 subunits of caspase-8 and caspase-3. Phosphopeptide mapping revealed that these phosphorylations occurred on serine-364 and serine-150, respectively. Introduction of mutated (S150A), but not wild-type, TAT-tagged caspase-3 into primary neutrophils made the Fas-induced apoptotic response insensitive to p38-MAPK inhibition. Consequently, p38-MAPK can directly phosphorylate and inhibit the activities of caspase-8 and caspase-3 and thereby hinder neutrophil apoptosis, and, in so doing, regulate the inflammatory response.
|
|
| 10. |
|
|
