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| 2. |
- Andersson, Mats R., et al.
(författare)
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Regioselective polymerization of 3-(4-octylphenyl)thiophene with FeCl3
- 1994
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Ingår i: Macromolecules. - : American Chemical Society. - 0024-9297 .- 1520-5835. ; 27:22, s. 6503-6506
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Tidskriftsartikel (refereegranskat)abstract
- We have shown that it is possible to regioselectively polymerize 3-(4-octylphenyl) thiophene with FeCl3. Adding FeCl3 slowly to the monomer leads to a soft and therefore regioselective polymerization. The head-to-tail content was determined by H-1 NMR to be 94 +/- 2%. Thin films of the polymer treated with chloroform vapor have an absorption maximum at 602 nm (2.06 eV) with clear vibronic fine structure. Free standing films have a conductivity of 4 S/cm, which is 100 times higher than for earlier prepared poly(3-(4-octylphenyl)thiophene). A mechanism for the regioregular polymerization is also proposed.
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| 3. |
- Andersson, Sebastian, et al.
(författare)
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Establishing epistemic practices in students’ formulation of scientifically researchable questions in upper secondary science education
- 2019
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Ingår i: NOFA7 ABSTRACTS Stockholm University, 13 - 15 May 2019. ; , s. 24-24
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The development of students' capability to engage in scientific inquiry is part of the science curricula across the educational system. However, previous research shows that laboratory and practical work in science education do not necessarily develop the capability to engage in scientific inquiry or contribute to developing an understanding of the nature of inquiry. The purpose of this study is to explore how teaching activities can be designed with a specific focus to develop students' capability to formulate questions for scientific inquiry. Some science education research points to that in order for students to develop an understanding of the nature of science inquiry, teaching has to include activities explicitly focusing aspects of inquiry such as asking questions, observing and making inferences. In this study we draw on the theoretical framework of epistemic practices to analyse and design teaching with the purpose of developing students' capabilities to formulate questions for scientific inquiry. Epistemic practices refer to the ways people in a specific community propose, justify, evaluate and legitimize knowledge claims within a disciplinary framework. From this perspective, formulating scientifically researchable questions makes sense only as part of epistemic practice in relation to a motive of knowledge production. The research question is: How can epistemic practices be established in upper-secondary school science where students are invited to participate in activities of formulating researchable questions?The study was carried out as a design-based research collaboration with a research team consisting of nine science teachers and four science education researchers. Data was collected in three cycles of design, intervention and analysis of research lessons with six classes in three different upper-secondary schools. The data consists of video-recordings of student interaction while engaging in tasks of formulating researchable scientific questions. The data is analysed using the didactical model of organizing purposes; distinguishing between overarching purposes and the student-orientated purposes emerging in interaction. The results indicate that the development of students’ capabilities to formulate researchable questions is situated in the processes of interaction with peers, and the conditions for situating the formulation of questions in a practice characterised by closeness to an epistemic object and gathering of observational data. Based on the results, we argue for a shift in science education from focusing students’ views of a generic nature of science or nature of science inquiry to focussing student participation in epistemic practices of various kinds.
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| 4. |
- Andersson, Sebastian, et al.
(författare)
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Students’ capabilities to formulate scientifically researchable questions in upper secondary science education
- 2019
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Ingår i: NOFA7 ABSTRACTS Stockholm University, 13 - 15 May 2019. ; , s. 25-25
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A goal for science education is to develop student capabilities to participate in scientific inquiry. This includes various aspects of inquiry; formulating scientifically researchable questions as well as planning, performing, analyzing and presenting science investigations. In science education practices, there is a tradition of using practical or laboratory work to illustrate science concepts; focussing correct answers and reproduction of ready-made scientific knowledge, rather than engaging students in inquiry. Previous research shows that inquiry teaching predominantly engage students in investigating science questions as formulated beforehand by the teacher or a textbook. Little attention has been paid to what might characterize the capability of formulating scientifically researchable questions in school. In this study we draw on a theoretical framework of epistemic practices. Epistemic practices refer to the ways people in a specific community propose, justify, evaluate and legitimize knowledge claims within a disciplinary framework. From this perspective, formulating and developing scientifically researchable questions makes sense only in relation to a motive of knowledge production. The aim of this study is to explore what might characterize students’ capabilities to formulate and develop scientifically researchable questions in upper secondary science education.The collected data consists of video-recordings of student interaction in group-work focussing formulating and developing scientifically researchable questions. Data was collected as part of a design-based study with six classes in three different schools. The video-recordings were transcribed in verbatim and analysed by the means of qualitative content analysis. The preliminary results suggest three themes: Formulation of scientifically researchable questions as:1) Working with the specification of the epistemic object. The theme illustrates how the students elaborated on the meaning of related scientific concepts and discussed cause and effect. 2) Specifying researchability by focussing on how to operationalize the epistemic object. The theme illustrates how the students reformulate their questions as part of a process of discussing e.g. measurability and variables.3) Making value-judgements of epistemic objects. The theme illustrates how the students distinguish between scientific and non-scientific questions and make value-judgements about relevance. The results contribute to an understanding of what the capability to engage in scientific inquiry as participation in collective epistemic work in an upper-secondary school science classroom might entail. The themes are related to the establishing of a specific scientific epistemic object. The results are discussed in relation to previous research in science education and the development of resources for teaching inquiry framing capabilities of inquiry as generic.
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| 5. |
- 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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| 6. |
- Berggren, Magnus, et al.
(författare)
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Green Electroluminescence in Poly-(3-cyclohexylthiophene) light-emitting diodes
- 1994
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag Berlin. - 0935-9648 .- 1521-4095. ; 6:6, s. 488-490
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Tidskriftsartikel (refereegranskat)abstract
- Electoluminescent devices based on polythiophene-system this films have been demonstrated that together span the entire visible range, steric hindrance being used to vary the bandgap between compunds. Poly-(3-cyclohexylthiophene), see Figures, exhibits green electoluminescence. Possible interpretations of this observation are proposed.
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| 7. |
- Berggren, Magnus, et al.
(författare)
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Thermal control of near‐infrared and visible electroluminescence in alkyl‐phenyl substituted polythiophenes
- 1994
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 65:12, s. 1489-1491
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Tidskriftsartikel (refereegranskat)abstract
- We report electroluminescence from a regioregular alkyl-phenyl substituted polythiophene. The polymer film exists in two forms, giving widely different optical absorption, as well as photoluminescence and electroluminescence spectra. In the low-bandgap form, we observe high emission intensity centered at 1.55 eV (800 nm), well into the infrared, while the high-bandgap form gives a maximum at 1.85 eV (670 nm). The conversion from the high-bandgap form to the low-bandgap form can be done by thermal treatment of the polymer light emitting diodes.
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| 8. |
- 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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| 9. |
- Hansson, Sverker, 1946, et al.
(författare)
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Dimercapto-succinic acid scintigraphy instead of voiding cystourethrography for infants with urinary tract infection.
- 2004
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Ingår i: The Journal of urology. - : Ovid Technologies (Wolters Kluwer Health). - 0022-5347 .- 1527-3792. ; 172:3
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: We study the ability of dimercapto-succinic acid (DMSA) scintigraphy to predict the presence of dilating vesicoureteral reflux (VUR) in infants with urinary tract infection (UTI) to simplify the evaluation protocol. MATERIALS AND METHODS: A retrospective analysis of the records of 303 children younger than 2 years with initial UTI investigated with DMSA scintigraphy and voiding cystourethrography (VCU) within 3 months after UTI was performed. RESULTS: In 156 of the 303 children (51%) DMSA scintigraphy showed renal lesions. VUR was found in 80 patients (26%) and VUR grade significantly correlated with the presence of renal lesions. A normal DMSA scintigraphy and dilating VUR (grade III) occurred in 7 infants. At followup after 1 to 2 years, 6 of these 7 patients had normal DMSA scans and 1 had a scarred duplex kidney. VUR resolved spontaneously in 5 and improved spontaneously to grade 1 in 2 patients. None of the 7 children had recurrent UTI. CONCLUSIONS: DMSA scintigraphy in infants with UTI may replace VCU as a first line investigation. A strategy to perform VCU in only patients with renal lesions is proposed. In this study 147 of 303 VCUs would have been unnecessary as only 1 child with a damaged kidney was missed.
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| 10. |
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