| 1. |
- Adawi, Tom, 1970, et al.
(author)
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Characterizing Software Engineering Students' Discussions during Peer Instruction : Opportunities for Learning and Implications for Teaching
- 2016
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In: International Journal of Engineering Education. - 0949-149X. ; 32:2, s. 927-936
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Journal article (peer-reviewed)abstract
- Peer instruction is a method for activating students during lectures, which has gained a considerable amount of attention in higher education due to claims of dramatic improvement in learning gains. The purpose of this qualitative research study is to investigate what types of discussions engineering students engage in during a peer instruction session and what learning possibilities that are enabled by these different types of discussions. We observed twelve students during six separate and simulated peer instruction sessions and the students were interviewed individually after the sessions.Ananalysis of the data revealed that the students engaged in three qualitatively different types of discussions: affirmative discussions, motivating discussions, and argumentative discussions. We characterize these different types of discussions in terms of the number of alternative answers the students discuss, the extent to which they draw on prior knowledge and experiences, as well as the fundamental difference between an explanation and an argument. A good opportunity for learning is opened up when students are aspiring to find the truth, not simply being satisfied with what they believe to be true. We conclude that students do not always engage in discussions that support their learning in the best way, and we discuss implications for using peer instruction as a teaching method.
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| 2. |
- Ahrentorp, Fredrik, et al.
(author)
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Sensitive magnetic biodetection using magnetic multi-core nanoparticles and RCA coils
- 2017
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In: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 427, s. 14-18
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Journal article (peer-reviewed)abstract
- We use functionalized iron oxide magnetic multi-core particles of 100 nm in size (hydrodynamic particle diameter) and AC susceptometry (ACS) methods to measure the binding reactions between the magnetic nanoparticles (MNPs) and bio-analyte products produced from DNA segments using the rolling circle amplification (RCA) method. We use sensitive induction detection techniques in order to measure the ACS response. The DNA is amplified via RCA to generate RCA coils with a specific size that is dependent on the amplification time. After about 75 min of amplification we obtain an average RCA coil diameter of about 1 mu m. We determine a theoretical limit of detection (LOD) in the range of 11 attomole (corresponding to an analyte concentration of 55 fM for a sample volume of 200 mu L) from the ACS dynamic response after the MNPs have bound to the RCA coils and the measured ACS readout noise. We also discuss further possible improvements of the LOD.
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| 3. |
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| 4. |
- Andersson, Helene, 1983, et al.
(author)
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The influence of the molecular weight of the water-soluble polymer on phase-separated films for controlled release
- 2016
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In: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 511:1, s. 223-235
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Journal article (peer-reviewed)abstract
- Hydroxypropyl cellulose (HPC) and ethyl cellulose (EC) can be used for extended release coatings, where the water-soluble HPC may act as a pore former. The aim was to investigate the effect of the molecular weight of HPC on the microstructure and mass transport in phase-separated freestanding EC/HPC films with 30% w/w HPC. Four different HPC grades were used, with weight averaged molecular weights (Mw) of 30.0 (SSL), 55.0 (SL), 83.5 (L) and 365 (M) kg/mol. Results showed that the phase-separated structure changed from HPC-discontinuous to bicontinuous with increasing Mw of HPC. The film with the lowest Mw HPC (SSL) had unconnected oval-shaped HPC-rich domains, leaked almost no HPC and had the lowest water permeability. The remaining higher Mw films had connected complex-shaped pores, which resulted in higher permeabilities. The highest Mw film (M) had the smallest pores and very slow HPC leakage, which led to a slow increase in permeability. Films with grade L and SL released most of their HPC, yet the permeability of the L film was three times higher due to greater pore connectivity. It was concluded that the phase-separated microstructure, the level of pore percolation and the leakage rate of HPC will be affected by the choice of HPC Mw grade used in the film and this will in turn have strong impact on the film permeability.
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| 5. |
- Andersson Trojer, Markus, et al.
(author)
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Elastic strain-hardening and shear-thickening exhibited by thermoreversible physical hydrogels based on poly(alkylene oxide)-grafted hyaluronic acid or carboxymethylcellulose
- 2020
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In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 22:26, s. 14579-14590
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Journal article (peer-reviewed)abstract
- The formation of strongly elastic physical gels based on poly(alkylene oxide)-grafted hyaluronan or carboxymethylcellulose, exhibiting both shear-thickening and strain-hardening have been studied using rheometry and explained using a slightly different interpretation of the transient network theory. The graft copolymers were prepared by a quantitative coupling reaction. Their aqueous solutions displayed a thermoreversible continuous transition from Newtonian fluid to viscoelastic solid which could be controlled by the reaction conditions. The evolution of all material properties of the gel could be categorized into two distinct temperature regimes with a fast evolution at low temperatures followed by a slow evolution at high temperatures. The activation energy of the zero shear viscosity and the relaxation time of the graft inside the interconnecting microdomains were almost identical to each other in both temperature regimes. This suggests that the number of microdomains remained approximately constant whereas the aggregation number inside the microdomains increased according to the binodal curve of the thermosensitive graft.
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| 6. |
- Andersson Trojer, Markus, 1981, et al.
(author)
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Polymer Core-Polymer Shell Particle Formation Enabled by Ultralow Interfacial Tension Via Internal Phase Separation: Morphology Prediction Using the Van Oss Formalism
- 2018
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In: Colloid and Interface Science Communications. - : Elsevier BV. - 2215-0382. ; 25, s. 36-40
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Journal article (peer-reviewed)abstract
- The internal phase separation technique is a versatile method for liquid core-polymer shell formation, yet limited to very hydrophobic core materials and actives. The use of polymeric cores instead circumvents this restriction due to the absent mixing entropy for binary polymer mixtures which allows the polymeric core (and the active) to approach the polarity of the shell. Polystyrene core-shell and janus particles were formulated using polymethylmethacrylate, poly(lactic acid), poly(lactic acid-co-glycolic acid), poly(epsilon-caprolactone) or cellulose triacetate as shell-forming polymers. The morphology and the partitioning was experimentally determined by selectively staining the core and the shell with beta-carotene and methylene blue respectively. In addition, the van Oss formalism was introduced to theoretically predict the thermodynamic equilibrium morphology. As elucidated using the theoretical predictions as well as experimental optical tensiometry, it was found that the driving force for core-shell morphology is, in contrast to liquid core-polymer shell particles, a low core-shell interfacial tension.
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| 7. |
- Andersson Trojer, Markus, 1981, et al.
(author)
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Quantitative Grafting for Structure-Function Establishment: Thermoresponsive Poly(alkylene oxide) Graft Copolymers Based on Hyaluronic Acid and Carboxymethylcellulose
- 2019
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In: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 20:3, s. 1271-1280
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Journal article (peer-reviewed)abstract
- © 2019 American Chemical Society. A series of thermoresponsive graft copolymers, gelling at physiological conditions in aqueous solution and cell growth media, have been synthesized using quantitative coupling between a small set of amino-functionalized poly(alkylene oxide) copolymers (PAO) and the carboxylate of the biologically important polysaccharides (PSa) carboxymethylcellulose and the less reactive hyaluronate. Quantitative grafting enables the establishment of structure-function relationship which is imperative for controlling the properties of in situ gelling hydrogels. The EDC/NHS-mediated reaction was monitored using SEC-MALLS, which revealed that all PAOs were grafted onto the PSa backbone. Aqueous solutions of the graft copolymers were Newtonian fluids at room temperatures and formed reversible physical gels at elevated temperatures which were noncytotoxic toward chondrocytes. The established structure-function relationship was most clearly demonstrated by inspecting the thermogelling strength and the onset of thermogelling in a phase diagram. The onset of the thermogelling function could be controlled by the global PAO concentration, independent of graft ratio.
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| 8. |
- Andersson Trojer, Markus, et al.
(author)
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Use of anchoring amphiphilic diblock copolymers for encapsulation of hydrophilic actives in polymeric microcapsules : methodology and encapsulation efficiency
- 2019
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In: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 297:2, s. 307-313
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Journal article (peer-reviewed)abstract
- Aqueous core-shell particles based on polystyrene, poly(methyl methacrylate) or polycaprolactone have been formulated using a facile double emulsion-based solvent evaporation method. The size distribution is narrow, and the morphology control is remarkable given the simple characteristics of the encapsulation method. The inner droplets are stabilized by oil-soluble poly(ethylene oxide)-based block copolymers which are anchored in the polymeric shell by using hydrophobic blocks of the same type as that of the shell-forming polymer. This facilitates the efficient encapsulation of dyes and hydrophilic biocides. [Figure not available: see fulltext.].
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| 9. |
- Andersson, Viktor, 1983, et al.
(author)
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Alkali interactions with a calcium manganite oxygen carrier used in chemical looping combustion
- 2022
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In: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 227
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Journal article (peer-reviewed)abstract
- Chemical-Looping Combustion (CLC) of biofuels is a promising technology for cost-efficient CO2 separation and can lead to negative CO2 emissions when combined with carbon capture and storage. A potential challenge in developing CLC technology is the effects of alkali metal-containing compounds released during fuel conversion. This study investigates the interactions between alkali and an oxygen carrier (OC), CaMn0.775Ti0.125Mg0.1O3-δ, to better understand the fate of alkali in CLC. A laboratory-scale fluidized bed reactor is operated at 800–900 °C in oxidizing, reducing and inert atmospheres to mimic CLC conditions. Alkali is fed to the reactor as aerosol KCl particles, and alkali in the exhaust is measured online with a surface ionization detector. The alkali concentration changes with gas environment, temperature, and alkali loading, and the concentration profile has excellent reproducibility over repeated redox cycles. Alkali-OC interactions are dominated by alkali uptake under most conditions, except for a release during OC reduction. Uptake is significant during stable reducing conditions, and is limited under oxidizing conditions. The total uptake during a redox cycle is favored by a high alkali loading, while the influence of temperature is weak. The implications for the understanding of alkali behavior in CLC and further development are discussed.
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| 10. |
- Andersson, Viktor, 1983, et al.
(author)
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Alkali-wall interactions in a laboratory-scale reactor for chemical looping combustion studies
- 2021
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In: Fuel Processing Technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 217
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Journal article (peer-reviewed)abstract
- Alkali metal-containing compounds are readily released during thermal conversion of solid fuels, and may have both detrimental and beneficial effects on chemical looping combustion. Here, we characterize alkali interactions with the inner walls of a laboratory-scale reactor under oxidizing, reducing and inert conditions at temperatures up to 900 °C. KCl aerosol particles are continuously introduced to the stainless steel reactor and the alkali concentration is measured on-line with a surface ionization detector. Aerosol particles evaporate at temperatures above 500 °C and KCl molecules rapidly diffuse to the reactor wall. Up to 92% of the alkali reaching the wall below 700 °C remains adsorbed, while re-evaporation is important at higher temperatures, where up to 74% remains adsorbed. Transient changes in alkali concentration are observed during repeated redox cycles, which are associated with changes in chemical composition of the wall material. Metal oxides on the reactor wall are partially depleted under reducing conditions, which allow for the formation of a new potassium-rich phase that is stable in a reducing atmosphere, but not under inert conditions. The observed wall effects are concluded to be extensive and include major transient effects depending on gas composition, and the implications for laboratory studies and improved experimental methodology are discussed.
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