| 1. |
- Alexanderson, Helena, et al.
(författare)
-
Optical dating of a Late Quaternary sediment sequence from Sokli, northern Finland
- 2008
-
Ingår i: Geochronometria. - : Walter de Gruyter GmbH. ; 32, s. 51-59
-
Tidskriftsartikel (refereegranskat)abstract
- Interstadial and non-glacial stadial sediments collected in boreholes from Sokli in northeastern Finland have been dated by optically stimulated luminescence on quartz and feldspar grains. The quartz OSL ages follow stratigraphic order, with one exception, and support the litho- and biostratigraphical correlation with the NW European mainland climate-stratigraphy and the marine oxygen-isotope stages. Feldspar IRSL dates generally overestimate the age, probably due to incomplete bleaching. The data show that during the last glacial cycle northeastern Finland was not glaciated until MIS 5b, around 90 ka. Interstadial conditions occurred around ~94 ka (MIS 5c), ~74-80 ka (MIS 5a) and 42-54 ka (MIS 3). The OSL ages have large standard errors mainly due to small sample sizes, relatively poor luminescence characteristics and uncertainties in dose-rate determinations.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Lastusaari, Mika, et al.
(författare)
-
The Bologna Stone: history's first persistent luminescent material
- 2012
-
Ingår i: European Journal of Mineralogy. - : Schweizerbart. - 1617-4011 .- 0935-1221. ; 24:5, s. 885-890
-
Tidskriftsartikel (refereegranskat)abstract
- In 1603, the Italian shoemaker Vincenzo Cascariolo found that a stone (baryte) from the outskirts of Bologna emitted light in the dark without any external excitation source. However, the calcination of the baryte was needed prior to this observation. The stone later named as the Bologna Stone was among the first luminescent materials and the first documented material to show persistent luminescence. The mechanism behind the persistent emission in this material has remained a mystery ever since. In this work, the Bologna Stone (BaS) was prepared from the natural baryte (Bologna, Italy) used by Cascariolo. Its properties, e. g. impurities (dopants) and their valences, luminescence, persistent luminescence and trap structure, were compared to those of the pure BaS materials doped with different (transition) metals (Cu, Ag, Pb) known to yield strong luminescence. The work was carried out by using different methods (XANES, TL, VUV-UV-vis luminescence, TGA-DTA, XPD). A plausible mechanism for the persistent luminescence from the Bologna Stone with Cu+ as the emitting species was constructed based on the results obtained. The puzzle of the Bologna Stone can thus be considered as resolved after some 400 years of studies.
|
|
| 5. |
- Niemelä, Matti, et al.
(författare)
-
Randomized Comparison of Final Kissing Balloon Dilatation Versus No Final Kissing Balloon Dilatation in Patients With Coronary Bifurcation Lesions Treated With Main Vessel Stenting : The nordic-baltic bifurcation study III
- 2011
-
Ingår i: Circulation. - 0009-7322 .- 1524-4539. ; 123:1, s. 79-86
-
Tidskriftsartikel (refereegranskat)abstract
- Background-It is unknown whether the preferred 1-stent bifurcation stenting approach with stenting of the main vessel (MV) and optional side branch stenting using drug-eluting stents should be finalized by a kissing balloon dilatation (FKBD). Therefore, we compared strategies of MV stenting with and without FKBD. Methods and Results-We randomized 477 patients with a bifurcation lesion to FKBD (n=238) or no FKBD (n=239) after MV stenting. The primary end point was major adverse cardiac events: cardiac death, non-procedure-related index lesion myocardial infarction, target lesion revascularization, or stent thrombosis within 6 months. The 6-month major adverse cardiac event rates were 2.1% and 2.5% (P=1.00) in the FKBD and no-FKBD groups, respectively. Procedure and fluoroscopy times were longer and more contrast media was needed in the FKBD group than in the no-FKBD group. Three hundred twenty-six patients had a quantitative coronary assessment. At 8 months, the rate of binary (re) stenosis in the entire bifurcation lesion (MV and side branch) was 11.0% versus 17.3% (P=0.11), in the MV was 3.1% versus 2.5% (P=0.68), and in the side branch was 7.9% versus 15.4% (P=0.039) in the FKBD versus no-FKBD groups, respectively. In patients with true bifurcation lesions, the side branch restenosis rate was 7.6% versus 20.0% (P=0.024) in the FKBD and no-FKBD groups, respectively. Conclusions-MV stenting strategies with and without FKBD were associated with similar clinical outcomes. FKBD reduced angiographic side branch (re) stenosis, especially in patients with true bifurcation lesions. The simple no-FKBD procedures resulted in reduced use of contrast media and shorter procedure and fluoroscopy times. Long-term data on stent thrombosis are needed. Clinical Trial Registration-URL: http://clinicaltrials.gov. Unique identifier: NCT00914199. (Circulation. 2011;123:79-86.)
|
|
| 6. |
- Pihlgren, Laura, et al.
(författare)
-
On the mechanism of persistent up-conversion luminescence in the ZrO2:Yb3+,Er3+ nanomaterials
- 2014
-
Ingår i: Optical Materials. - : Elsevier BV. - 0925-3467. ; 36:10, s. 1698-1704
-
Tidskriftsartikel (refereegranskat)abstract
- The up-converting ZrO2:Yb3+,E3+ nanomaterials were prepared with the combustion and sal-gel methods. The structure of the materials was cubic except for the minor monoclinic and tetragonal impurities associated with the use of the sal-gel method. The XANES results revealed only the trivalent form for both the Yb and Er dopants. The distance distributions calculated from EXAFS confirm that Er3+ and Yb3+ occupy the Zr-IV site in the structure. The nanomaterials show red (650-700 nm) and very weak green (520-560 nm) up-conversion luminescence due to the F-4(9/2) -> I-4(15/2) and (H-2(11/2),S-4(3/2)) -> I-4(15/2) transitions of Er3+, respectively. The nanomaterials obtained with the combustion synthesis yield the most intense luminescence though showing significant afterglow, as well. The thermoluminescence measurements revealed the existence of traps with depths between 0.68 and 1.03 eV well matching to room temperature persistent emission. Finally, the mechanism for the persistent up-conversion luminescence was introduced based on the experimental results and discussed. (C) 2014 Elsevier B.V. All rights reserved.
|
|
