| 1. |
- Ahmed, Istaq, 1972, et al.
(författare)
-
Location of deuteron sites in the proton conducting perovskite BaZr0.50In0.50O3-y
- 2008
-
Ingår i: Journal of Alloys and Compounds. - : Elsevier BV. - 0925-8388. ; 450:1-2, s. 103-110
-
Tidskriftsartikel (refereegranskat)abstract
- High-resolution neutron powder diffraction data have been collected on deuterated and dried samples of the perovskite BaZr0.5In0.5O2.75 at 5 K and room temperature, respectively. Inspection of Fourier nuclear density maps for the deuterated phase have allowed the deuteron position to be refined on a 12h (1/2, y, 0) crystallographic site, with y = 0.217(4) yielding a chemically reasonable O-D distance of 0.92(2) angstrom. Evidence for anisotropy of the deuteron position is also found consistent with a 24k crystallographic site (0.56, 0.21, 0) indicative of displacements of the ion towards neighbouring oxygen ions. The presence of static oxygen disorder in both the dried and deuterated samples is apparent from the structural analyses. Raman spectra confirm short range deviations from cubic symmetry for both dried and hydrated samples.
|
|
| 2. |
|
|
| 3. |
- Ahmed, Istaq, 1972, et al.
(författare)
-
Synthesis and structural characterization of perovskite type proton conducting BaZr1-xInxO3-delta (0.0 <= x <= 0.75)
- 2006
-
Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738 .- 1872-7689. ; 177:17-18, s. 1395-1403
-
Tidskriftsartikel (refereegranskat)abstract
- Solid state sintering has been used to prepare the cubic perovskite structured compounds BaZr1-xInxO3-delta (0.0 <= x <= 0.75). Analysis of X-ray powder diffraction (XRPD) data reveals that the unit cell parameter, a, increases linearly with an increased Indium concentration. XRPD data was also used to demonstrate the completion of sample hydration, which was reached when the materials showed a set of single-phase Bragg-peaks. Dynamic thermogravimetric analysis (TGA) data showed that approx. 89% of the total number of available oxygen vacancies can be filled in BaZr1-xInxO3-delta for x=0.50, and that the maximum water uptake occurs below 300 degrees C. Rietveld analysis of the room temperature neutron powder diffraction (NPD) data confirmed the average cubic symmetry (space group Pm-3m), and an expansion of the unit cell parameter after the hydration reaction. The strong O-H stretch band, 2500-3500 cm(-1), in the infrared absorbance spectrum clearly manifests the presence of protons in the hydrated material. Proton conductivity of hydrated BaZr1-xInxO3-delta, x=0.75 was investigated during heating and cooling cycles under dry argon atmosphere. The total conductivity during the heating cycle was nearly two orders of magnitude greater than that of cooling cycle at 300 degrees C, whilst these values were similar at higher temperatures i.e. T > 600 degrees C.
|
|
| 4. |
- Karlsson, Maths, et al.
(författare)
-
Quasielastic neutron scattering of hydrated BaZr(0.90)A(0.10)O(2.95) (A = Y and Sc)
- 2009
-
Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 180:1, s. 22-28
-
Tidskriftsartikel (refereegranskat)abstract
- Proton motions in hydrated proton conducting perovskites BaZr(0.90)A(0.10)O(2.95) (A = Y and Sc) have been investigated using quasielastic neutron scattering. The results reveal a localized motion on the ps time scale and with an activation energy of similar to 10-30 meV, in both materials. The temperature dependence of the total mean square displacement of the protons shows an onset of this motion at a temperature of about 300 K. The low activation energy, much lower than the activation energy for the macroscopic proton conductivity, suggests that this motion is not the rate-limiting process for the long-range proton diffusion, i.e. it is not linked to the two materials significantly different proton conductivities. In fact, a comparison of the QENS results with density functional theory calculations indicates that for both materials the observed motion may be ascribed to intra-octahedral proton transfers occurring close to a dopant atom. (C) 2008 Elsevier B.V. All rights reserved.
|
|
| 5. |
- Karlsson, Maths, 1978, et al.
(författare)
-
Quasielastic neutron scattering of hydrated BaZr0.90A0.10O2.95 (A = Y and Sc)
- 2009
-
Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 180:1, s. 22-28
-
Tidskriftsartikel (refereegranskat)abstract
- Proton motions in hydrated proton conducting perovskites BaZr 0.90 A 0.10 O 2.95 (A = Y and Sc) have been investigated using quasielastic neutron scattering. The results reveal a localized motion on the ps time scale and with an activation energy of ~ 10-30 meV, in both materials. The temperature dependence of the total mean square displacement of the protons shows an onset of this motion at a temperature of about 300 K. The low activation energy, much lower than the activation energy for the macroscopic proton conductivity, suggests that this motion is not the rate-limiting process for the long-range proton diffusion, i.e. it is not linked to the two materials significantly different proton conductivities. In fact, a comparison of the QENS results with density functional theory calculations indicates that for both materials the observed motion may be ascribed to intra-octahedral proton transfers occurring close to a dopant atom. © 2008 Elsevier B.V. All rights reserved.
|
|
| 6. |
- Karlsson, Maths, 1978, et al.
(författare)
-
Vibrational Properties of Protons in Hydrated BaInxZr1-xO3-x/2
- 2005
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 72, s. 1-7
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the local proton dynamics in the proton conducting hydrated perovskite system BaInxZr1-xO3-x/2 (x=0.25-0.75) using infrared spectroscopy and first-principles calculations. We show that oxygen vacancies and dopant atoms in the vicinity of the proton tilt the proton toward a neighboring oxygen creating strongly hydrogen-bonded configurations. This is manifested as a strong redshift of the O-H stretch band in the infrared absorption spectrum. We also find considerable fluctuations of the nearest and next-nearest oxygen-proton distances with time, resulting in additional spectral broadening. By comparing the frequencies of computed O-H stretch modes we can relate specific local configurations to different parts of the broad O-H stretch band. Even though hydrogen-bonded configurations favor proton transfer they hinder the long-range migration by decreasing the reorientational rate. Thus, in order to optimize the proton mobility it is important to avoid extreme configurations caused by either oxygen vacancies or dopant atoms in the perovskite structure.
|
|
| 7. |
- Larsson, Dennis, et al.
(författare)
-
Rapid activation of JNK/SAPK in LNCaP prostate cancer cells by 1α,25-dihydroxyvitamin D3 is independent of PDIA3 (1,25-MARRS)
- 2008
-
Ingår i: Current Topics in Steroid Research. - : Research Trends. - 0972-4788. ; 5, s. 17-24
-
Tidskriftsartikel (refereegranskat)abstract
- 1α,25-dihydroxyvitamin D3 (1,25D3 ) is a highly potential anti-cancerous agent for prevention and treatment of prostate cancer, the most commonly diagnosed cancer type of males in western countries. A recent study by our laboratory, demonstrates that LNCaP cancer cells treated with 1,25D3, evoked dose-dependent activation of the JNK/SAPK MAPK signaling pathway within 10 minutes after hormone treatment, indicative of membrane-initiated steroid signaling (MISS) by 1,25D3. This confirms previous reports on intestinal-, chondrocyte- and osteoblast cells, where 1,25D3 operates through pharmacologically distinct nuclear-initiated mechanisms (NISS) and plasma membrane-initiated mechanisms. NISS is mediated via the vitamin D receptor (nVDR) and MISS is mediated through 1,25D3-MARRS (PDIA3, 1,25D3-membraneassociated rapid response steroid binding protein) or nVDR. The aims of the present study were to investigate the mechanisms of MISS evoked effects on alkaline phosphatase (ALP) and activation of the JNK/SAPK by 1,25D3, and the involvement of PDIA3 in 1,25D3 initiated activation of the JNK/SAPK signaling pathway. Furthermore, 1,25D3-treated LNCaP cells were transfected with siRNA against PDIA3 and phosphorylated JNK/SAPK was estimated by western analysis. Western analysis and ALP-assays demonstrated rapid activation of both JNK/SAPK as well as ALP. Silencing of PDIA3 did not affect 1,25D3 mediated activation of JNK/SAPK, suggesting that PDIA3 is not involved in the 1,25D3-initiated activation of the JNK/SAPK signaling pathway.
|
|
| 8. |
- Lindblad-Toh, Kerstin, et al.
(författare)
-
Genome sequence, comparative analysis and haplotype structure of the domestic dog.
- 2005
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 438:7069, s. 803-19
-
Tidskriftsartikel (refereegranskat)abstract
- Here we report a high-quality draft genome sequence of the domestic dog (Canis familiaris), together with a dense map of single nucleotide polymorphisms (SNPs) across breeds. The dog is of particular interest because it provides important evolutionary information and because existing breeds show great phenotypic diversity for morphological, physiological and behavioural traits. We use sequence comparison with the primate and rodent lineages to shed light on the structure and evolution of genomes and genes. Notably, the majority of the most highly conserved non-coding sequences in mammalian genomes are clustered near a small subset of genes with important roles in development. Analysis of SNPs reveals long-range haplotypes across the entire dog genome, and defines the nature of genetic diversity within and across breeds. The current SNP map now makes it possible for genome-wide association studies to identify genes responsible for diseases and traits, with important consequences for human and companion animal health.
|
|
