| 1. |
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| 2. |
- Wroblewski, R, et al.
(författare)
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X-ray microanalysis of in situ and isolated pancreatic islets
- 1998
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Ingår i: Pancreas. - 0885-3177 .- 1536-4828. ; 16:2, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- The effect of stimulation of insulin secretion in pancreatic beta cells on the elemental composition ofthese cells was investigated by x-ray microanalysis. In vitro experiments on isolated islets ofLangerhans from ob/ob mice were compared to in situ experiments. The only significant difference inthe elemental composition of beta cells from ob/ob mice versus their lean counterparts is a lower Ca concentration in the ob/ob animals. The nucleus of the beta cells has a higher concentration of P, K, and Na than the cytoplasm, which has a higher concentration of S and Cl. No polarized ion distributionin the cytoplasm of the beta cells was observed. Isolated beta cells show a higher concentration of Na and Cl and a lower concentration of K than their in situ counterparts. Stimulation of insulin secretion with glucose both in situ and in vitro showed only very small effects on the elemental composition of the beta cells: a tendency to a decreased P content was noted. In vitro experiments using stimulation with high extracellular K+ showed, in addition, a small increase in the intracellular K concentration. Inconclusion, while the elemental content of beta cells in vitro differs from that in situ, the response to glucose stimulation appears to be similar in both systems.
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| 3. |
- Xing, K. Z., et al.
(författare)
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The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
- 1996
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 76:1-3, s. 263-267
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Tidskriftsartikel (refereegranskat)abstract
- The electronic and geometric structures of poly [3-(4-octylphenyl)thiophene] have been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Thermochromic effects, and new charge induced states generated by potassium doping, have been observed by direct UPS measurements. The experimental results are in very good agreement with the results of theoretical quantum chemical calculations performed with the Austin Model 1 semi-empirical model and the valence-effective Hamiltonian pseudo-potential model.
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| 4. |
- Xing, K. Z., et al.
(författare)
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The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
- 1996
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 80:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of poly [3-(4-octylphenyl)thiophene] (POPT) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS), as well as by quantum chemical calculations. Both temperature-dependent effects on the electronic structure of the neutral system, as well as the generation of new electronic states induced by doping with alkaline metals, have been observed. The experimental results are in good agreement with the results of the quantum chemical calculations.
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| 5. |
- Andersson, Mats R., et al.
(författare)
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Electroluminescence from Substituted Poly(thiophenes) : From Blue to Near-Infrared
- 1995
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 28:22, s. 7525-7529
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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%.
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| 6. |
- Andersson, Mats R., et al.
(författare)
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Improved photoluminescence efficiency of films from conjugated polymers
- 1997
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 85:1-3, s. 1383-1384
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Tidskriftsartikel (refereegranskat)abstract
- We have demonstrated two general ways to increase the photoluminescence efficiency of films from conjugated polymers. One is to disperse the conjugated polymer on a molecular level by using attractive forces between the conjugated polymer and the matrix. The other method is to substitute the conjugated polymer with side chains which separates the conjugated backbones. Using this idea a new poly(thiophene) with a photoluminescence efficiency of 16% in films has been prepared. LEDs from this polymer exhibit an external efficiency of 0.1% for single layer and 0.7% for double layer diodes.
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| 7. |
- Andersson, Mats R., et al.
(författare)
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Synthesis of poly(alkylthiophenes) for light-emitting diodes
- 1995
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2183-2184
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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.
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| 8. |
- Berggren, Magnus, et al.
(författare)
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Controlling colour by voltage in polymer light emitting diodes
- 1995
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2185-2186
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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.
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| 9. |
- Berggren, Magnus, 1968-, et al.
(författare)
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Light amplification in organic thin films using cascade energy transfer
- 1997
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 389, s. 466-469
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Tidskriftsartikel (refereegranskat)abstract
- There is currently renewed interest in the development of lasers using solid-state organic and polymeric materials as the gain media. These materials have a number of properties that make them good candidates for such applications — for example, emission bands that are displaced (via a Stokes shift) from absorption bands, and the ease with which the emitting species can be embedded in a suitable host material1, 2, 3, 4, 5. But despite these advantages, the threshold power densities required for light amplification that have been reported so far have been high6, 7, 8. Here we describe an approach, based on energy transfer between molecular species, that can lower the threshold for stimulated emission and laser action while improving markedly the waveguiding properties of the active material. In our materials, an initial molecular excited state is generated in the host compound by absorption of light; this state is then resonantly and non-radiatively transferred down in energy (through one or more steps) between suitably matched dye molecules dispersed in the host, so ensuring that the absorption losses at the final emission wavelengths are very small. Such composite gain media provide provide broad tunability of the emission wavelength, and also decouple the optical emission properties from the transport properties, so providing greater flexibility for the design of future electrically driven device structures.
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| 10. |
- Berggren, Magnus, 1968-, et al.
(författare)
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Organic laser based on lithographically defined photonic-bandgap resonators
- 1998
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Ingår i: Electronics Letters. - : IEEE. - 0013-5194 .- 1350-911X. ; 34:1, s. 90-91
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Tidskriftsartikel (refereegranskat)abstract
- The authors report the fabrication and characteristics of organic solid-state waveguide lasers with feedback from a photolithographically defined rhomboid photonic bandgap lattice. The lattice is formed by etching holes of depth 10-40 nm in SiO2 and filling them with the organic gain medium. The gain medium is part of a planar waveguide formed by air/organic layer/SiO2.
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| 11. |
- Berggren, Magnus, et al.
(författare)
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Polymer light-emitting diodes placed in microcavities
- 1996
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 76:1-3, s. 121-123
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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.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Dodabalapur, A., et al.
(författare)
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Applied physics - Organic solid-state lasers : Past and future
- 1997
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Ingår i: Science. - : American Association for the Advancement of Science. - 0036-8075 .- 1095-9203. ; 277:5333, s. 1787-1788
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Researchers around the world are seeking organic materials that can be made into practical and efficient lasers. In their Perspective, Dodabalapur et al. review the past history and future prospects of this important class of laser materials.
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| 18. |
- Dyreklev, Peter, et al.
(författare)
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Polarized electroluminescence from an oriented substituted polythiophene in a light emitting diode
- 1995
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag Berlin. - 0935-9648 .- 1521-4095. ; 7:1, s. 43-45
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Tidskriftsartikel (refereegranskat)abstract
- Polarized light sources based on stretch-oriented conjugated polymers are reported. The devices, based on poly 3(4-octylphenyl)-2,2′-bithiophene, show an external quantum efficiency of 0.1% and are produced using a very simple method which may be easily extended to other polymers. The fabrication of the devices is described and factors such as the emission and spectral differences parallel and prependicular to the stretching direction discussed.
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| 19. |
- Eliasson, Lena, et al.
(författare)
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PKC-dependent stimulation of exocytosis by sulfonylureas in pancreatic beta cells
- 1996
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 271:5250, s. 813-815
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Tidskriftsartikel (refereegranskat)abstract
- Hypoglycemic sulfonylureas represent a group of clinically useful antidiabetic compounds that stimulate insulin secretion from pancreatic beta cells. The molecular mechanisms involved are not fully understood but are believed to involve inhibition of potassium channels sensitive to adenosine triphosphate (KATP channels) in the beta cell membrane, causing membrane depolarization, calcium influx, and activation of the secretory machinery. In addition to these effects, sulfonylureas also promoted exocytosis by direct interaction with the secretory machinery not involving closure of the plasma membrane KATP channels. This effect was dependent on protein kinase C (PKC) and was observed at therapeutic concentrations of sulfonylureas, which suggests that it contributes to their hypoglycemic action in diabetics.
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| 20. |
- Engervall, K, et al.
(författare)
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Borreliosis as a cause of peripheral facial palsy: a multi-center study
- 1995
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Ingår i: ORL. - 0301-1569. ; 57:4, s. 202-206
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Tidskriftsartikel (refereegranskat)abstract
- Borreliosis is known to be a common cause of peripheral facial palsy in Stockholm and its vicinity. The aim of the present study was to investigate the frequency and characteristics of borreliosis among patients with peripheral facial palsy in different parts of Sweden. All serological tests were performed in one laboratory. Ten Swedish Ear Nose and Throat clinics participated in a prospective 1-year study of patients seeking medical attention for acute peripheral facial palsy. Twenty-eight (6%) out of totally 446 patients fulfilled the criteria for the diagnosis of borreliosis. The frequency varied between 1 and 16% and was highest along the southeast coast of Sweden whereas no case was reported from the northern part of the country. Borreliosis was more common among children with facial palsy than among adults. The infection occurred during all seasons although it appears to be less frequent during the spring months. Only a minority of the borrelial patients had a history of a preceding tick bite or erythema migrans. The fairly low overall frequency of this secondary stage of borreliosis in the study may be a result of better knowledge of the disease and earlier treatment of its early manifestations. In Sweden's endemic areas borreliosis is a common cause of peripheral facial palsy, and therefore all patients with facial palsy in these regions should be examined for borrelial infection.
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| 21. |
- Granström, Magnus, et al.
(författare)
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Phase separation of conjugated polymers - Tools for new functions in polymer LEDs
- 1997
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 85:1-3, s. 1193-1194
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Tidskriftsartikel (refereegranskat)abstract
- Within the single family of substituted poly(thiophenes) it is possible to realize such diverse device designs as voltage controlled colours from polymer LEDs, sub-micron size LEDs, and white light emitters. Many of these features become possible by the use of polymer blends in which one or more poly(thiophenes) are mixed with a matrix polymer (PMMA). The phase structure in these blends can be controlled by stoichiometry and mode of formation. That phase structure can be used to prevent exciton transfer, and to define new colours in polymer LEDs. It also allows us to make anisotropic conductors suitable for contacting optical devices.
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| 22. |
- Granström, Magnus, et al.
(författare)
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Self organizing polymer films - a route to novel electronic devices based on conjugated polymers
- 1997
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Ingår i: Supramolecular science. - : ELSEVIER SCI LTD. - 0968-5677 .- 1873-4146. ; 4:1-2, s. 27-34
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Tidskriftsartikel (refereegranskat)abstract
- Polymer blends are often used in polymer light emitting diodes as a tool to increase the efficiency of the devices. In this report, we show the necessity to take the phase separation properties of such blends into account, as the miscibility of the involved polymers drastically affects the resulting film structure. By using phase separated polymer blends involving conjugated poly(thiophenes) and different nonconjugated polymers as matrices, different types of applications, such as light emitting diodes with improved voltage control of emitted colour, sub-micron size LEDs and anisotropic conductors are demonstrated. (C) 1997 Elsevier Science Ltd. All rights reserved.
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| 23. |
- Inganäs, Olle, et al.
(författare)
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Thiophene polymers in light emitting diodes : Making multicolour devices
- 1995
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2121-2124
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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.
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| 24. |
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| 25. |
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| 26. |
- Larsson, O, et al.
(författare)
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Oscillations in KATP channel activity promote oscillations in cytoplasmic free Ca2+ concentration in the pancreatic beta cell
- 1996
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 93:10, s. 5161-5165
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic beta cells exhibit oscillations in electrical activity, cytoplasmic free Ca2+ concentration ([Ca2+](i)), and insulin release upon glucose stimulation. The mechanism by which these oscillations are generated is not known. Here we demonstrate fluctuations in the activity of the ATP-dependent K+ channels (K(ATP) channels) in single beta cells subject to glucose stimulation or to stimulation with low concentrations of tolbutamide. During stimulation with glucose or low concentrations of tolbutamide, K(ATP) channel activity decreased and action potentials ensued. After 2-3 min, despite continuous stimulation, action potentials subsided and openings of K(ATP) channels could again be observed. Transient suppression of metabolism by azide in glucose-stimulated beta cells caused reversible termination of electrical activity, mimicking the spontaneous changes observed with continuous glucose stimulation. Thus, oscillations in K(ATP) channel activity during continuous glucose stimulation result in oscillations in electrical activity and [Ca2+](i).
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| 27. |
- Luhr, O., et al.
(författare)
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A retrospective analysis of nitric oxide inhalation in patients with severe acute lung injury in Sweden and Norway 1991-1994
- 1997
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 41:10, s. 1238-46
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Patients with severe acute lung injury (ALI) have been treated compassionately on doctors' initiative with inhaled nitric oxide (INO) in Sweden and Norway since 1991. In 1994 the previously used technical grade nitric oxide was replaced by medical grade nitric oxide. METHODS: We have carried out a retrospective data collection on all identified adult patients treated with INO for >4 h during the period 1991-1994 focusing on safety aspects and patient outcome. We used the following exclusion criteria (1) Age <18 years, (2) Simultaneous treatment with extracorporeal removal of CO2 (3) NO inhalation period <4 h, (4) Incomplete or missing patient charts, (5) Use of INO in order to treat pulmonary hypertension following cardiac surgery, with little or no acute lung injury. RESULTS: Inclusion criteria were met by 56 out of 73 identified patients. Mean age was 48+/-19 years and the median duration of INO treatment was 102 h. PaO2/FIO2 ratio at start of treatment was 85 +/- 33 mm Hg with a lung injury score (LIS) of 3.2+/-0.8. The aetiology of the lung injury was pneumonia (n= 27), sepsis (n=12) and trauma (n=8). Survival to hospital discharge was 41% and survival after 180 d was 38%. Three serious adverse events were identified, two from technical failures of the INO delivery device and one withdrawal reaction necessitating slow weaning from INO. No methaemoglobin values >5% were reported during treatment. CONCLUSION: The overall mortality did not differ dramatically from historical controls with high mortality. Only a randomised study may determine whether INO as an adjunct to treatment alters the outcome in severe ALI. One cannot at present advocate the routine use of INO in patients with ALI outside such studies.
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| 28. |
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| 29. |
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| 30. |
- Ostrick, J. R., et al.
(författare)
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Conductivity-type anisotropy in molecular solids
- 1997
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 81:10, s. 6804-6808
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Tidskriftsartikel (refereegranskat)abstract
- Thin polycrystalline films of perylenetetracarboxylic dianyhydride (PTCDA), an organic molecular solid, exhibits substantial anisotropies in its electronic transport properties. Only electrons transport in the directions along molecular planes, while mainly holes transport in the direction normal to molecular planes. A series of measurements on both field effect transistors with PTCDA active layers and light emitting diodes with PTCDA transport layers documents the anisotropy seen in the electronic transport in thin films of PTCDA. (C) 1997 American Institute of Physics.
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| 31. |
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