| 1. |
|
|
| 2. |
- Dicke, B., et al.
(författare)
-
Transferring the entatic-state principle to copper photochemistry
- 2018
-
Ingår i: Nature Chemistry. - : NATURE PUBLISHING GROUP. - 1755-4330 .- 1755-4349. ; 10:3, s. 355-362
-
Tidskriftsartikel (refereegranskat)abstract
- The entatic state denotes a distorted coordination geometry of a complex from its typical arrangement that generates an improvement to its function. The entatic-state principle has been observed to apply to copper electron-transfer proteins and it results in a lowering of the reorganization energy of the electron-transfer process. It is thus crucial for a multitude of biochemical processes, but its importance to photoactive complexes is unexplored. Here we study a copper complex-with a specifically designed constraining ligand geometry-that exhibits metal-to-ligand charge-transfer state lifetimes that are very short. The guanidine-quinoline ligand used here acts on the bis(chelated) copper(I) centre, allowing only small structural changes after photoexcitation that result in very fast structural dynamics. The data were collected using a multimethod approach that featured time-resolved ultraviolet-visible, infrared and X-ray absorption and optical emission spectroscopy. Through supporting density functional calculations, we deliver a detailed picture of the structural dynamics in the picosecond-to-nanosecond time range.
|
|
| 3. |
- Dicke, B., et al.
(författare)
-
Transferring the entatic-state principle to copper photochemistry
- 2018
-
Ingår i: Nature Chemistry. - : Springer Science and Business Media LLC. - 1755-4349 .- 1755-4330. ; 10:3, s. 355-362
-
Tidskriftsartikel (refereegranskat)abstract
- The entatic state denotes a distorted coordination geometry of a complex from its typical arrangement that generates an improvement to its function. The entatic-state principle has been observed to apply to copper electron-transfer proteins and it results in a lowering of the reorganization energy of the electron-transfer process. It is thus crucial for a multitude of biochemical processes, but its importance to photoactive complexes is unexplored. Here we study a copper complex-with a specifically designed constraining ligand geometry-that exhibits metal-to-ligand charge-transfer state lifetimes that are very short. The guanidine-quinoline ligand used here acts on the bis(chelated) copper(I) centre, allowing only small structural changes after photoexcitation that result in very fast structural dynamics. The data were collected using a multimethod approach that featured time-resolved ultraviolet-visible, infrared and X-ray absorption and optical emission spectroscopy. Through supporting density functional calculations, we deliver a detailed picture of the structural dynamics in the picosecond-to-nanosecond time range.
|
|
| 4. |
- Kuhn, Hans-Georg, 1961, et al.
(författare)
-
Increased generation of granule cells in adult Bcl-2-overexpressing mice: a role for cell death during continued hippocampal neurogenesis
- 2005
-
Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 22:8, s. 1907-1915
-
Tidskriftsartikel (refereegranskat)abstract
- Programmed cell death is an important mechanism during brain development in order to control neuronal cell numbers and to correctly form neuronal circuitries. Programmed cell death is also present in neurogenic regions of the adult brain, and a significant portion of the adult-born cells is eliminated during the first months of maturation. We here address the question whether overexpression of the anti-apoptotic protein Bcl-2 would improve the survival of neural progenitor cells and, as a consequence, increase neurogenesis in the adult hippocampus. Transgenic animals, which express human Bcl-2 under the neuron-specific enolase promoter (NSE-huBcl-2), show a significant reduction of apoptotic cells in the hippocampal granule cell layer to about half of the wild-type level. These apoptotic cells are almost exclusively found in the zone of hippocampal progenitor activity and frequently co-label with the neuronal progenitor marker doublecortin (DCX). The rate of adult neurogenesis is doubled in the dentate gyrus of Bcl-2-overexpressing mice as demonstrated by quantification of progenitor cells using DCX and new neurons using bromodeoxyuridine (BrdU)/neuronal nuclei antigen (NeuN) double-labelling. The effect of Bcl-2 is limited to the late phase of progenitor maturation, as proliferation and early-phase progenitor cells were not affected. The increased level of neurogenesis leads to a significantly higher total number of granule cells in the dentate gyrus. These results underline the importance of developmental cell death during neurogenesis in the adult brain.
|
|
| 5. |
- Mazzei, Laura, 1988, et al.
(författare)
-
Phonon spectra of pure and acceptor doped BaZrO3 investigated with visible and UV Raman spectroscopy
- 2020
-
Ingår i: Journal of Physics Condensed Matter. - 0953-8984 .- 1361-648X. ; 32:40
-
Tidskriftsartikel (refereegranskat)abstract
- We report results from visible and UV Raman spectroscopy studies of the phonon spectra of a polycrystalline sample of the prototypical perovskite type oxide BaZrO3 and a 500 nm thick film of its Y-doped, proton conducting, counterpart BaZr0.8Y0.2O2.9. Analysis of the Raman spectra measured using different excitation energies (between 3.44 eV and 5.17 eV) reveals the activation of strong resonance Raman effects involving all lattice vibrational modes. Specifically, two characteristic energies were identified for BaZrO3, one around 5 eV and one at higher energy, respectively, and one for BaZr0.8Y0.2O2.9, above 5 eV. Apart from the large difference in spectral intensity between the non-resonant and resonant conditions, the spectra are overall similar to each other, suggesting that the vibrational spectra of the perovskites are stable when investigated using an UV laser as excitation source. These results encourage further use of UV Raman spectroscopy as a novel approach for the study of lattice vibrational dynamics and local structure in proton conducting perovskites, and open up for, e.g., time-resolved experiments on thin films targeted at understanding the role of lattice vibrations in proton transport in these kinds of materials.
|
|
