| 1. |
- Da, Silva A.F., et al.
(författare)
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Asymmetric nonlinear amplitude in patterns of porous silicon
- 2000
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Ingår i: Physica A. - 0378-4371 .- 1873-2119. ; 283:1, s. 223-227
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Tidskriftsartikel (refereegranskat)abstract
- A gradient pattern analysis is used to report a phenomenogical evidence of asymmetric nonlinear spatial distribution of porous silicon structures. We used a canonical sample set obtained from scanning force microscopy. Due to the high sensitivity of the gradient field operator, it is possible to correlate the photoluminescence performance of porous silicon with different degree of asymmetries and spatial nonlinearity. A generalization of this new approach to quantify nonlinear amplitude fragmentation in complex lattices is proposed.
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| 2. |
- Ferreira, Da Silva A., et al.
(författare)
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Characterization of asymmetric fragmentation patterns in SFM images of porous silicon
- 2000
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Ingår i: Solid State Communications. - 0038-1098 .- 1879-2766. ; 113:12, s. 703-708
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Tidskriftsartikel (refereegranskat)abstract
- Due to possible technological applications in opto-electronic devices, the interest in characterizing porous silicon structure patterns has recently increased. From scanning force microscopy (SFM) we have obtained images of different samples of porous silicon and applied pattern characterization operators on these matrices. In this paper, asymmetric spatial fragmentation in amplitude envelopes of porous silicon samples are characterized by means of a parameter that quantifies the amount of spatial asymmetry in the gradient field. The results show that this method is well suited to characterize silicon porosity quantitatively.
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| 3. |
- Arias, A.C., et al.
(författare)
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Use of tin oxide thin films as a transparent electrode in PPV based light-emitting diodes
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 371:1, s. 201-206
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Tidskriftsartikel (refereegranskat)abstract
- Tin oxide (TO) thin films, nominally undoped, have been used as electrodes in poly(p-phenylene vinylene) (PPV) based organic electroluminescent devices. The evolution of the crystallinity and the electrical resistance of TO films submitted to the PPV thermal conversion conditions, have been investigated. It has been found that the electrical resistance is decreased whereas the crystallinity of the film is increased. It is shown in this work, that the photoluminescence of PPV converted on top of TO substrates is not as quenched as it is when converted on top of indium-tin oxide (ITO) substrates. The quantum efficiency of light-emitting diode is 0.07% at 17 V forward bias. It is also shown that the work function of TO films is very stable to different cleaning procedures, in contrast with previous results obtained for ITO films.
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| 4. |
- Borlado, CR, et al.
(författare)
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Neutron strain scanning on bimetallic tubes
- 2000
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Ingår i: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING. - : ELSEVIER SCIENCE SA. - 0921-5093. ; 288:2, s. 288-292
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Tidskriftsartikel (refereegranskat)abstract
- Neutron diffraction measurements have been carried out on the REST diffractometer (Studsvik) on curved components fabricated by cold working bimetallic tubes. The tubes consist of two layers (an outer one of austenitic steel and an inner one of ferritic s
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| 5. |
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| 6. |
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| 7. |
- Ding, L., et al.
(författare)
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Photovoltaic cells with a conjugated polyelectrolyte
- 2000
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 110:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- We describe photovoltaic cells made from a novel conjugated polyelectrolyte, the lithium salt of poly(thiophene-3-acetic acid) (PTAA-Li). The aqueous solubility of this polyelectrolyte allows formation of blend electrodes with a dispersion of the metallic polymer Poly(Ethylene DiOxyThiophene) (PEDOT). The incident monochromatic photon to current conversion efficiency (IPCE) of the cells were improved up to 19% by blending PTAA-Li with PEDOT to modify the ITO electrode, in combination with the low bandgap polymer poly(3-(4-octylphenyl)thiophene) (POPT), and C60 as electron acceptor. We attribute the increase of efficiency to the improved contact area between the conjugated polyelectrolyte and PEDOT.
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| 8. |
- Gerdts, E., et al.
(författare)
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Impact of age on left ventricular hypertrophy regression during antihypertensive treatment with losartan or atenolol (the LIFE study)
- 2004
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Ingår i: J Hum Hypertens. - 0950-9240. ; 18:6, s. 417-22
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Tidskriftsartikel (refereegranskat)abstract
- To assess the influence of age on changes in left ventricular (LV) mass and geometry during antihypertensive treatment, we related age to clinical and echocardiographic findings before and after 4 years of antihypertensive treatment in a subset of 560 hypertensive patients without known concurrent disease in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, which randomized patients to blinded losartan- or atenolol-based treatment. Patients >/=65 years (older group) included more women and patients with isolated systolic hypertension or albuminuria (all P<0.05). Compared to patients <65 years, older patients had higher pulse pressure, LV mass, and prevalence of concentric hypertrophy at baseline (78 vs 69 mmHg, 234 vs 224 g, and 28 vs 16%, respectively, all P<0.01), while the mean blood pressure did not differ. Over 4 years, reductions in LV mass and the mean blood pressure were similar in both groups, but older patients more often had residual hypertrophy (31 vs 15%, P<0.001) with a preponderance of eccentric geometry. In multivariate analysis of 4-year change in LV mass controlling for baseline mass, larger hypertrophy reduction was associated with losartan treatment, while age, gender, body mass index, and 4-year change in pulse pressure and albuminuria did not enter (Multiple R (2)=0.40, P<0.001). Thus, in up-to-80-year-old hypertensive patients with left ventricular hypertrophy, age did not significantly attenuate hypertrophy reduction during antihypertensive treatment, although residual hypertrophy was more prevalent in older patients as a consequence of higher initial LV mass.
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| 9. |
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| 10. |
- Inganäs, Olle, et al.
(författare)
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Recent progress in thin film organic photodiodes
- 2001
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Ingår i: Synthetic metals. - 0379-6779 .- 1879-3290. ; 121:1-3, s. 1525-1528
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Tidskriftsartikel (refereegranskat)abstract
- We review current developments in organic photodiodes, with special reference to multilayer thin film optics, and modeling of organic donor-acceptor photodiodes. We indicate possibilities to enhance light absorption in devices by nanopatterning as well as by blending, and also discuss materials science issues of nanostructure in blends and in vertically stratified multilayer devices. Our current best devices have external efficiencies of 30-50% in between 400-600 nm, and show fill factors of 0.54 illuminated under weak monochromatic light.
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