| 1. |
- Fredriksson, Åsa, 1968, et al.
(författare)
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Effects of aging and reproduction on protein quality control in soma and gametes of Drosophila melanogaster
- 2012
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Ingår i: Aging Cell. - : Wiley. - 1474-9718. ; 11:4, s. 634-643
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Tidskriftsartikel (refereegranskat)abstract
- In organisms with a somagerm demarcation, the germline must be preserved such that harmful damage is not transmitted to the offspring. Keeping the progeny free of damage may be achieved by gametes enjoying elevated, and/or more functional, homeostatic maintenance systems. This possibility was approached here by testing whether the soma and maturating oocytes (eggs) dissected from female Drosophila melanogaster in reproductive ages display differential capacities for protein quality control and whether these capacities change during aging and mating. Eggs exhibited a high capacity to prevent protein aggregation, strong capacity for 26S proteasome-dependent degradation and reduced levels of oxidatively damaged (carbonylated) proteins compared to the soma. The capacity to prevent protein aggregation was not affected in either soma or eggs by age and/or mating, while the 26S proteasome capacity declined in the soma but was maintained in the eggs of aged females. However, the levels of carbonylated proteins increased with age in both soma and eggs, and this increase was more pronounced in females allowed to mate continuously. Furthermore, the levels of carbonylated proteins in the eggs of mated flies correlated negatively with the propensity of the eggs to develop into an adult fly. In young flies, mating caused a decrease in 26S proteasome capacity and an increase in protein carbonylation in the soma, but not in the eggs. These results are in line with trade-off theories of aging where aging is considered a consequence of investment in reproduction over somatic maintenance.
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| 4. |
- Berggren, Elin, et al.
(författare)
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Charge Transfer in the P(g42T-T) : BBL Organic Polymer Heterojunction Measured with Core-Hole Clock Spectroscopy
- 2023
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 127:49, s. 23733-23742
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Tidskriftsartikel (refereegranskat)abstract
- The conductivity of organic polymer heterojunction devices relies on the electron dynamics occurring along interfaces between the acceptor and donor moieties. To investigate these dynamics with chemical specificity, spectroscopic techniques are employed to obtain localized snapshots of the electron behavior at selected interfaces. In this study, charge transfer in blends (by weight 10, 50, 90, and 100%) of p-type polymer P(g(4)2T-T) (bithiophene-thiophene) and n-type polymer BBL (poly(benzimidazo-benzo-phenanthroline)) was measured by resonant Auger spectroscopy. Electron spectra emanating from the decay of core-excited states created upon X-ray absorption in the donor polymer P(g(4)2T-T) were measured in the sulfur KL2,3L2,3 Auger kinetic energy region as a function of the excitation energy. By tuning the photon energy across the sulfur K-absorption edge, it is possible to differentiate between decay paths in which the core-excited electron remained on the atom with the core-hole and those where it tunneled away. Analyzing the competing decay modes of these localized and delocalized (charge-transfer) processes facilitated the computation of charge-transfer times as a function of excitation energy using the core-hole clock method. The electron delocalization times derived from the measurements were found to be in the as/fs regime for all polymer blends, with the fastest charge transfer occurring in the sample with an equal amount of donor and acceptor polymer. These findings highlight the significance of core-hole clock spectroscopy as a chemically specific tool for examining the local charge tunneling propensity, which is fundamental to understanding macroscopic conductivity. Additionally, the X-ray absorption spectra near the sulfur K-edge in the P(g(4)2T-T) polymer for different polymer blends were analyzed to compare molecular structure, orientation, and ordering in the polymer heterojunctions. The 50% donor sample exhibited the most pronounced angular dependence of absorption, indicating a higher level of ordering compared to the other weight blends. Our studies on the electron dynamics of this type of all-polymer donor-acceptor systems, in which spontaneous ground-state electron transfer occurs, provide us with critical insights to further advance the next generation of organic conductors with mixed electron-hole conduction characteristics suitable for highly stable electrodes of relevance for electronic, electrochemical, and optoelectronic applications.
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| 5. |
- Dods, Robert, 1989, et al.
(författare)
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Ultrafast structural changes within a photosynthetic reaction centre.
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7841, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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| 6. |
- Fritze, Stefan, et al.
(författare)
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Elemental distribution and fracture properties of magnetron sputtered carbon supersaturated tungsten films
- 2024
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Ingår i: Surface & Coatings Technology. - : Elsevier BV. - 0257-8972 .- 1879-3347. ; 477
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Tidskriftsartikel (refereegranskat)abstract
- The combination of strength and toughness is a major driving force for alloy design of protective coatings, and nanocrystalline tungsten (W)-alloys have shown to be promising candidates for combining strength and toughness. Here we investigate the elemental distribution and the fracture toughness of carbon (C) alloyed W thin films prepared by non-reactive magnetron sputtering. W:C films with up to ~4 at.% C crystallize in a body-centered-cubic structure with a strong 〈hh0〉texture, and no additional carbide phases are observed in the diffraction pattern. Atom probe tomography and X-ray photoelectron spectroscopy confirmed the formation of such a supersaturated solid solution. The pure W film has a hardness ~13 GPa and the W:C films exhibit a peak hardness of ~24 GPa. In-situ micromechanical cantilever bending tests show that the fracture toughness decreases from ~4.5 MPa·m1/2 for the W film to ~3.1 MPa·m1/2 for W:C films. The results show that C can significantly enhance the hardness of W thin films while retaining a high fracture toughness.
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| 7. |
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| 8. |
- Johansson, Elin, 1978, et al.
(författare)
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Experiences, appearances, and interprofessional training: The instructional use of video in post-simulation debriefings
- 2017
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Ingår i: International Journal of Computer-Supported Collaborative Learning. - : Springer Science and Business Media LLC. - 1556-1607 .- 1556-1615. ; 12:1, s. 91-112
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Tidskriftsartikel (refereegranskat)abstract
- © 2017 The Author(s)Through close analyses of the interaction that takes place between students and facilitators, this study investigates the instructional use of video in post-simulation debriefings. The empirical material consists of recordings of 40 debriefings that took place after simulation-based training scenarios in health care education. During the debriefings, short video-recorded sequences of the students’ collaboration in the scenarios were shown, after which the facilitators asked the students questions about the teamwork and their performance as displayed in these sequences. The aim of the study is to show: a) how the video is consequential for the ways in which the students talk about the teamwork and their own performance; b) how the facilitators’ questions guide the students’ contributions and collaborative sense making of prior events. Regularly, the facilitators’ questions were posed in terms of “seeing”. The design and sequential environment of the questions made it relevant for the students to comment on how the displayed situations appeared audiovisually and how these appearances contrasted with their experiences from the situation. In this way, the video enabled the students to talk about their own conduct, including their collaboration with their peers, from a third-person perspective. The study highlights the central role of instructions and instructional questions in the debriefings, how the video was used to make the students reconceptualise their performance together with others, and the importance of contributions from fellow students.
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| 12. |
- Johansson, Elin, 1978, et al.
(författare)
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Inter-professional teamwork in emergency care: pedagogical use of video in post-simulation debriefings
- 2014
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Ingår i: SESAM 2014, 20th Anniversary SESAM Meeting Poznań 12-14 June 2014.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- MAIN ABSTRACT Background: The use of video for feedback in debriefings is widespread and considered to be essential for the effective use of simulations. However, empirical studies that focus on how video can be optimized as a pedagogical means in debriefings are still rare. Objective: The study aims to investigate how video can be used to encourage reflection and discussion on scenarios in subsequent debriefings. Methods: The data consists of forty video recorded debriefings following interprofessional team training scenarios for medical and nursing students. First, a number of video sequences were selected from the debriefings in which the facilitators used video-clips from the scenario as a basis for discussion. These represented a variation of the ways in which video clips were introduced. The video sequences then served as basis for a focus group interview with three facilitators. The interview explored the variation in introducing the video clips and what implications this had for subsequent discussions. Results: Different strategies for introducing video clips were identified, ranging from very specific to very open-ended. Whilst the specific ones were characterized by detailed information about the situation and what parts of the clip to focus on, the open-ended introductions were characterized by brief information about the situation without instructions for what aspects to focus on. The interview resulted in a model involving four interrelated factors – moment of time in training, complexity of the situation, group characteristics and purpose ¬– that are important to take into account when choosing between open-ended versus specific introductions. Conclusions: The proposed model provides a conceptual tool for discussing and planning successful use of video recordings for feedback purposes in post-simulation debriefings. It can also be used to increase awareness of how the selection and introduction of video clips affect subsequent discussions.
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| 13. |
- Johansson, Elin, 1978, et al.
(författare)
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Pedagogical use of video for feedback and reflection in simulation-based team-training
- 2013
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Ingår i: Högskolepedagogisk konferens i Göteborg (HKG 2013). ABSTRACTS [VERSION 1.6 | 2013-10-14].
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Within the educational sciences, the use of video in providing feedback on student performance has been investigated in several research studies. The current study aligns to this interest and investigates how video recordings of simulation scenarios are used as basis for feedback and reflection in healthcare education. The data corpus consists of forty video recorded simulation sessions that were part of a team training of medical and nursing students. The sessions were designed to provide opportunities for joint team training in order to develop competencies for interprofessional collaboration. The use of simulations for team training of health care students and professionals has a long tradition. A common assumption is that facilitated feedback discussions (debriefings) are critical for positive learning outcomes to occur. Whether and how such effects are achieved, however, have not been thoroughly addressed (Fanning & Gaba, 2007). In recent years, the use of video recordings of simulated scenarios in subsequent debriefings has become common practice and it is often thought to be beneficial (cf. Dieckmann et al., 2008). In relation to simulation-based team training, the concept “video-assisted debriefing” is commonly used to describe a facilitated discussion where short video sequences are used as a basis for feedback and reflection on team conduct. Empirical studies on how video features in this practice are, however, mainly absent. The general aim of the presentation is to address how video recordings can be used as a ground for feedback and reflection in facilitated group discussions in various educational settings. Based on short video sequences from the data material, the presentation will address how the use of video contributes to in-depth discussions on specific aspects of teamwork in the simulation scenario. Preliminary analyses indicate that selection of episodes, the introduction and framing of them as well as how they subsequently are discussed all are important for how the debriefings evolve. In the recorded sessions, two methods for introducing and following-up the video clips have been observed. One approach applied by the facilitators is to be very specific about the aspects that should be subject for discussion, whilst another is to be more open-ended and hand over to the students what aspects to focus on. In the present study, the significance of the facilitators’ questions and framing of the clips are subject to further analysis. References Dieckmann, P., Reddersen, S., Zieger, J., & Rall, M. (2008). A structure for video-assisted debriefing in simulator-basedtraining of crisis resource management. In R. Kyle & B. W. Murray (Eds.), Clinical Simulation: Operations, Engineering, and Management (pp. 667-676). Burlington: Academic Press. Fanning R.M. & Gaba D.M. (2007). The Role of Debriefing in Simulation-Based Learning. Simulation in Healthcare, 2(2): 115-125.
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| 14. |
- Johansson, Fredrik O. L., et al.
(författare)
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A Blyholder mechanism in the chemisorption of N2O on Ni(111) : studied with Auger-photoelectron coincidence spectroscopy
- 2024
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 666
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Tidskriftsartikel (refereegranskat)abstract
- In heterogeneous catalysis the surface-adsorbate bond strength is critical for the function of the system. Here we study a series consisting of multilayer, bilayer and monolayer N2O on Ni(111) and employ Auger-photoelectron coincidence spectroscopy (APECS) to study the interaction between the molecule and the substrate directly. We observe intensity in the nitrogen Auger spectra that arise from the interaction between molecule and surface (not observed in free molecules) whereas the oxygen spectra are thickness-independent. Since the two nitrogen atoms of N2O are chemically inequivalent we can assign the intensity present in the bilayer and monolayer cases to orbitals centered on the terminal nitrogen which is closest to the Ni(111) surface. Using ab initio, molecular dynamics and solid-state density functional theory calculations we infer a Blyholder model of the surface bond as consisting of donation from the terminal nitrogen lone-pair valence orbital with back-donation from the metal into the unoccupied orbitals on that nitrogen. This coincidence technique can readily be used to study substrate–adsorbate interactions directly with chemical and orbital specificity — this opens up prospects to study fundamental steps of molecular adsorption and heterogeneous catalysis with unprecedented detail.
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| 15. |
- Johansson Krogh, Elin, 1978, et al.
(författare)
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Progression and specificity of protein oxidation in the life cycle of Arabidopsis thaliana
- 2004
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Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 279:21, s. 22204-22208
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Tidskriftsartikel (refereegranskat)abstract
- Protein carbonylation is an irreversible oxidative process leading to a loss of function of the modified proteins, and in a variety of model systems, including worms, flies, and mammals, carbonyl levels gradually increase with age. In contrast, we report here that in Arabidopsis thaliana an initial increase in protein oxidation during the first 20 days of the life cycle of the plant is followed by a drastic reduction in protein carbonyls prior to bolting and flower development. Protein carbonylation prior to the transition to flowering targets specific proteins such as Hsp70, ATP synthases, the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), and proteins involved in light harvesting/energy transfer and the C2 oxidative photosynthetic carbon cycle. The precipitous fall in protein carbonyl levels is due to the specific reduction in the levels of oxidized proteins rather than an overall loss of chlorophyll and Rubisco associated with the senescence syndrome. The results are discussed in light of contemporary theories of aging in animals
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| 16. |
- Lindwall, Oskar, 1974, et al.
(författare)
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The use of video in dental education: Clinical reality addressed as practical matters of production, interpretation and instruction
- 2014
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Ingår i: Studies of video practices : video at work / edited by Mathias Broth, Eric Laurier and Lorenza Mondada. - New York : Routledge. - 9780415728393 ; , s. 161-180
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Bokkapitel (refereegranskat)abstract
- Over the past half-century, clinical practitioners, educators and researchers have argued for the benefits of using video and television in dental education. Everything within the tooth is tiny and it is hard to provide light in the inner structures of the teeth. This does not only pose challenges to the practising dentist, but also to the student of dentistry. This chapter investigates how a combination of video and microscopes is used for instructional purposes. In the first part, the production of the instructional video is analysed. The second part investigates how the video is interpreted and explicated by the teacher.
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| 17. |
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| 18. |
- Rystedt, Hans, 1951, et al.
(författare)
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Seeing through the dentist's eyes: Video-based clinical demonstrations in preclinical dental training
- 2013
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Ingår i: Journal of Dental Education. - 1930-7837. ; 77:12, s. 1629-1638
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Tidskriftsartikel (refereegranskat)abstract
- The clinical demonstration is an established way of bridging the disciplinary content in preclinical and clinical courses. In dentistry, however, clinical demonstrations have often been perceived as less rewarding due to the restricted visual access to the details of the treatment. This study investigated a course in endodontics at the University of Gothenburg, Sweden, in which traditional clinical demonstrations were replaced by instructor-led seminars that enabled students to follow and discuss broadcasted root canal treatments. Two cameras provided overviews of the operating room, whereas a third camera attached to a surgical microscope offered a magnified view of procedures carried out in the inner parts of teeth. The hypothesis was that this arrangement would increase the students’ sense of the clinical relevance of basic scientific knowledge. Two focus group interviews were designed to explore the students’ perceptions of this change. The students expressed that the video-based seminars offered ample opportunities to integrate theoretical and clinical understanding. The major reasons were that the visualization displayed procedures on a sufficiently detailed level; instructors demonstrated clinical reasoning in situ and provided the context necessary for understanding procedures; and the interactive format encouraged discussions on the generalizability of knowledge beyond the specific case.
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| 19. |
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