| 1. |
- Rahman, M, et al.
(författare)
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GABA-site antagonism and pentobarbital actions do not depend on the alpha-subunit type in the recombinant rat GABA receptor.
- 2006
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Ingår i: Acta physiologica (Oxford, England). - : Wiley. - 1748-1708 .- 1748-1716. ; 187:4, s. 479-88
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Tidskriftsartikel (refereegranskat)abstract
- The roles of alpha-subunits on the gamma-aminobutyric acid (GABA)-site antagonism and pentobarbital actions were examined in rat recombinant GABA(A) receptors in Xenopus oocytes.Experiments were performed with binary and ternary GABA(A) receptors containing alpha1-, alpha4- or alpha5-subunit by the two-electrode voltage-clamp technique.The potency of GABA was significantly higher in the alpha1beta2, alpha4beta2 and alpha5beta2 receptors compared with the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors. However, the alpha5beta2 receptor possessed significantly lower GABA efficacy compared with the alpha5beta2gamma2L receptor. While the gamma2-subunit was essential to the potency of GABA, its influence on the apparent GABA-site antagonism was less profound. The antagonist affinity constants (K(B)) of bicuculline inhibition and slopes of Schild plots were similar between all types of ternary and binary receptors except alpha5beta2 receptor which was not tested. The pK(B)s and IC(50)s of the GABA-site antagonism were not significantly different between the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors. Bicuculline blocked pentobarbital-activated currents in a reversible and non-competitive manner with the alpha1beta2gamma2L, alpha4beta2gamma2L, and alpha5beta2gamma2L receptors, indicating an allosteric inhibition of the GABA-site. No significant difference of bicuculline potencies in inhibiting GABA- and pentobarbital-activated currents was found between the alpha1beta2gamma2L, alpha4beta2gamma2L and alpha5beta2gamma2L receptors.The GABA-site antagonism does not depend on the subtype of alpha-subunits. Similarly, pentobarbital activates ternary receptors composed of different alpha-subunits in a bicuculline-sensitive manner. The potencies of bicuculline to inhibit pentobarbital-activated currents are identical with receptors containing alpha1, alpha4 or alpha5-subunit. The alpha1beta2 and alpha4beta2 receptors possess higher GABA potencies compared with the alpha1beta2gamma2L and alpha4beta2gamma2L receptors.
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| 2. |
- Osada, M., et al.
(författare)
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In situ resonant Raman scattering and reversible photoinduced structural change in YBa2Cu3O6+x
- 2005
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 71
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Tidskriftsartikel (refereegranskat)abstract
- We report on bidirectional photoswitching associated with the CuO chains in oxygen-deficient YBa2Cu3O6+x single crystals. By varying the wavelength of light polarized along the CuO chains, the material can be reversibly switched between two metastable states characterized by the existence or absence of a specific Raman scattering resonance. A comparison of the spectral efficiencies for this photoswitching with analogous data for the persistent photoconductivity and photoconductivity quenching effects suggests that the two phenomena have the same microscopic origin. We argue that the effects are due to photoinduced Cu-O charge-transfer excitations, which destabilize chains of different length depending on wavelength, and promote the growth of thermally inaccessible oxygen ordering configurations.
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| 3. |
- Hudson, John A., et al.
(författare)
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Characterising and modelling the excavation damaged zone in crystalline rock in the context of radioactive waste disposal
- 2009
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Ingår i: Environmental Geology. - : Springer Science and Business Media LLC. - 0943-0105 .- 1432-0495. ; 57:6, s. 1275-1297
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes current knowledge about the nature of and potential for thermo-hydro-mechanical-chemical modelling of the excavation damaged zone (EDZ) around the excavations for an underground radioactive waste repository. In the first part of the paper, the disturbances associated with excavation are explained, together with reviews of Workshops that have been held on the subject. In the second part of the paper, the results of a DECOVALEX [DEmonstration of COupled models and their VALidation against EXperiment: research funded by an international consortium of radioactive waste regulators and implementers (http://www.decovalex.com)] research programme on modelling the EDZ are presented. Four research teams used four different models to simulate the complete stress-strain curve for Avro granite from the Swedish A"spo Hard Rock Laboratory. Subsequent research extended the work to computer simulation of the evolution of the repository using a 'wall-block model' and a 'near-field model'. This included assessing the evolution of stress, failure and permeability and time-dependent effects during repository evolution. As discussed, all the computer models are well suited to sensitivity studies for evaluating the influence of their respective supporting parameters on the complete stress-strain curve for rock and for modelling the EDZ.
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| 4. |
- Iliev, M. N., et al.
(författare)
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Comparative Raman studies of Sr$_2$RuO$_4$, Sr$_3$Ru$_2$O$_7$ and Sr$_4$Ru$_3$O$_10$
- 2005
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 358:1--4
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Tidskriftsartikel (refereegranskat)abstract
- The polarized Raman spectra of layered ruthenates of the Srn+1RunO3n+1 (n=1,2,3) Ruddlesden-Popper series were measured between 10 and 300 K. The phonon spectra of Sr3Ru2O7 and Sr4Ru3O10 confirmed earlier reports for correlated rotations of neighboring RuO6 octahedra within double or triple perovskite blocks. The observed Raman lines of Ag or B1g symmetry were assigned to particular atomic vibrations by considering the Raman modes in simplified structures with only one double or triple RuO6 layer per unit cell and by comparison to the predictions of lattice dynamical calculations for the real Pban and Pbam structures. Along with discrete phonon lines, a continuum scattering, presumably of electronic origin, is present in the zz, xx and xy, but not in the x'y' and zx spectra. Its interference with phonons results in Fano shape for some of the lines in the xx and xy spectra. The temperature dependences of phonon parameters of Sr3Ru2O7 exhibit no anomaly between 10 and 300 K where no magnetic transition occur. In contrast, two B1g lines in the spectra of Sr4Ru3O10, corresponding to oxygen vibrations modulating the Ru-O-Ru bond angle, show noticeable hardening with ferromagnetic ordering at 105 K, thus indicating strong spin-phonon interaction.
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| 5. |
- Iliev, M. N., et al.
(författare)
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Comparative Raman studies of Sr2RuO4, Sr 3Ru2O7 and Sr4Ru3O 10
- 2005
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Ingår i: Physica B: Condensed Matter. - : Elsevier BV. - 0921-4526. ; 358:1-4, s. 138-152
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Tidskriftsartikel (refereegranskat)abstract
- The polarized Raman spectra of layered ruthenates of the Srn+1RunO3n+1 (n=1,2,3) Ruddlesden-Popper series were measured between 10 and 300 K. The phonon spectra of Sr3Ru2O7 and Sr4Ru3O10 confirmed earlier reports for correlated rotations of neighboring RuO6 octahedra within double or triple perovskite blocks. The observed Raman lines of Ag or B1g symmetry were assigned to particular atomic vibrations by considering the Raman modes in simplified structures with only one double or triple RuO6 layer per unit cell and by comparison to the predictions of lattice dynamical calculations for the real Pban and Pbam structures. Along with discrete phonon lines, a continuum scattering, presumably of electronic origin, is present in the zz, xx and xy, but not in the x′y′ and zx spectra. Its interference with phonons results in Fano shape for some of the lines in the xx and xy spectra. The temperature dependences of phonon parameters of Sr3Ru2O7 exhibit no anomaly between 10 and 300 K where no magnetic transition occur. In contrast, two B1g lines in the spectra of Sr4Ru3O10, corresponding to oxygen vibrations modulating the Ru-O-Ru bond angle, show noticeable hardening with ferromagnetic ordering at 105 K, thus indicating strong spin-phonon interaction.
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| 9. |
- Schulz, B., et al.
(författare)
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Fully reflective deep ultraviolet to near infrared spectrometer and entrance optics for resonance Raman spectroscopy
- 2005
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Ingår i: Review of Scientific Instruments. - 0034-6748 .- 1089-7623. ; 76
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Tidskriftsartikel (refereegranskat)abstract
- We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000 nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO3, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4 eV. (c) 2005 American Institute of Physics.
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