| 1. |
- Andersson, Mats R., et al.
(författare)
-
Electroluminescence from Substituted Poly(thiophenes) : From Blue to Near-Infrared
- 1995
-
Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 28:22, s. 7525-7529
-
Tidskriftsartikel (refereegranskat)abstract
- We report a systematic approach to the control of the conjugation length along the poly(thiophene) backbone. The planarity of the main chain can be permanently modified by altering the pattern of substitution and character of the substituents on the poly(thiophene) chain, and the conjugation length is thus modified. We obtain blue, green, orange, red, and near-infrared electroluminescence from four chemically distinct poly(thiophenes). The external quantum efficiencies are in the range of 0.01-0.6%.
|
|
| 2. |
- Inganäs, Olle, et al.
(författare)
-
Thiophene polymers in light emitting diodes : Making multicolour devices
- 1995
-
Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2121-2124
-
Tidskriftsartikel (refereegranskat)abstract
- We can control the bandgap of thiophene polymers over 2 eV by choosing the nature, position and regularity of side chain substitutions. Electroluminescence from these polymers cover the full visible spectrum, from the blue into the near infra-red. Blends of these polymer materials allow us to construct voltage controlled variable colour light sources. A newly developed transfer technique allow us to mount thin oriented films of the polymers in polymer LEDs to obtain polarised light sources giving polarisation anisotropys of up to 3. Sub-lambda light sources have been constructed from these polymer materials using nanometer polymer electrodes.
|
|
| 3. |
- Andersson, Mats R., et al.
(författare)
-
Synthesis of poly(alkylthiophenes) for light-emitting diodes
- 1995
-
Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2183-2184
-
Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated a general way to tune the emission of poly(alkylthiophenes) by using steric interaction between the repeating units. Light-emitting diodes prepared of the polymers have blue to near-infrared emission.
|
|
| 4. |
- Berggren, Magnus, et al.
(författare)
-
Controlling colour by voltage in polymer light emitting diodes
- 1995
-
Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2185-2186
-
Tidskriftsartikel (refereegranskat)abstract
- We report electroluminescence using different substituted polythiophenes as the emitting mterial. Different substituents cause different sterical interacion which force the thiophene rings out of planarity. This results in different bandgaps. Colours from blue to near infrared have been demonstrated in electroluminescent devices. We also demonstrate voltage controlled electroluminescence using mixtures of these polymers.
|
|
| 5. |
- Berggren, Magnus, et al.
(författare)
-
Polymer light-emitting diodes placed in microcavities
- 1996
-
Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 76:1-3, s. 121-123
-
Tidskriftsartikel (refereegranskat)abstract
- The use of resonant optical microcavities to influence the emission properties of conjugated polymer light-emitting diodes (LEDs) is reported. The microcavities, which are built using metallic mirrors and polymeric spacers, incorporate polymer LEDs in between the mirrors. We report experimental results of polymer LEDs based on substituted polythiophenes. The effects include substantial narrowing of the spectral width of the emitted light, enhancement of the emission at the microcavity resonance, and coupling of two emission processes to different resonance modes in the same cavity.
|
|
| 6. |
- Berggren, Ulf, 1948, et al.
(författare)
-
Factor analysis and reduction of a Fear Survey Schedule among dental phobic patients.
- 1995
-
Ingår i: European journal of oral sciences. - 0909-8836 .- 1600-0722. ; 103:5, s. 331-8
-
Tidskriftsartikel (refereegranskat)abstract
- A fear survey instrument, based on the Fear Survey Schedule-II and five additional fear items, was administered to 109 patients (70 women and 39 men) on a waiting list at a specialized dental fear clinic. The fear survey was analyzed to identify its factorial structure. Five fear factors, explaining 54% of the total variance, were identified concerning areas of "illness and death", "failures and embarrassment", "social situations", "physical injuries", and "animals and natural phenomena". An ad hoc reduction of items was carried out to form a shorter, more practical to use questionnaire, which resulted in factors of four or five items with loadings greater than 0.50. The factors intercorrelated significantly (rp varying between 0.33 and 0.59) and "illness and death" correlated highly with "physical injuries" (rp = 0.59) and "animals and natural phenomena" (rp = 0.56), while "failures and embarrassment" correlated highly to "social situations" (rp = 0.54). Statistically significant, but generally lower correlations were found between each factor and the dental fear measures. The highest correlations were found between fear of "physical injuries" and dental fear. There was also a high and significant correlation between sex and fear of "animals and natural phenomena".
|
|
| 7. |
|
|
| 8. |
- Hakeberg, Magnus, 1954, et al.
(författare)
-
Multivariate analysis of fears in dental phobic patients according to a reduced FSS-II scale.
- 1995
-
Ingår i: European journal of oral sciences. - 0909-8836 .- 1600-0722. ; 103:5, s. 339-44
-
Tidskriftsartikel (refereegranskat)abstract
- This study analyzed and assessed dimensions of a questionnaire developed to measure general fears and phobias. A previous factor analysis among 109 dental phobics had revealed a five-factor structure with 22 items and an explained total variance of 54%. The present study analyzed the same material using a multivariate statistical procedure (LISREL) to reveal structural latent variables. The LISREL analysis, based on the correlation matrix, yielded a chi-square of 216.6 with 195 degrees of freedom (P = 0.138) and showed a model with seven latent variables. One was a general fear factor correlated to all 22 items. The other six factors concerned "Illness & Death" (5 items), "Failures & Embarrassment" (5 items), "Social situations" (5 items), "Physical injuries" (4 items), "Animals & Natural phenomena" (4 items). One item (opposite sex) was included in both "Failures & Embarrassment" and "Social situations". The last factor, "Social interaction", combined all the items in "Failures & Embarrassment" and "Social situations" (9 items). In conclusion, this multivariate statistical analysis (LISREL) revealed and confirmed a factor structure similar to our previous study, but added two important dimensions not shown with a traditional factor analysis. This reduced FSS-II version measures general fears and phobias and may be used on a routine clinical basis as well as in dental phobia research.
|
|
| 9. |
- Hakeberg, Magnus, 1954, et al.
(författare)
-
Repeated measurements of mood during psychologic treatment of dental fear.
- 1997
-
Ingår i: Acta odontologica Scandinavica. - 0001-6357 .- 1502-3850. ; 55:6, s. 378-83
-
Tidskriftsartikel (refereegranskat)abstract
- The aims of the present study were to analyze mood changes during psychologic treatment of dental fear by assessing the rate of improvement. Twenty-one patients who refused conventional dental treatment and reported extreme dental anxiety participated in the study. Levels of dental anxiety and mood were measured with the Dental Anxiety Scale (DAS) and a Mood Adjective Checklist (MACL). MACL included two dimensions, degree of relaxation (r) and pleasantness (h) as experienced in a dental situation. Mood was monitored at each treatment session from base line to termination of the therapy (eight measurements). Two different treatment modalities were used, one with a more cognitive approach (n = 9) and one emphasizing the relaxation component (n = 12). A hierarchical linear models approach was applied to analyze individual change with repeated measurements. The results showed that positive mood changes over time were statistically significant. The mean improvement in mood scores per week and session was estimated for MACL(r) and MACL(h) to be 0.14/week and 0.09/week, respectively. The growth was not affected by DAS levels or treatment mode. This study also illustrated a powerful method for analyzing a longitudinal clinical trial design with repeated measurements.
|
|
| 10. |
|
|
