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- Dufil, Gwennaël, 1995-
(författare)
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Living biohybrid systems via in vivo polymerization of thiophene oligomers
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Life is the result of a multitude of electrical signals which drives our nervous system but also accomplishes a cascade of electrochemical reactions. In the 18th century, Lucia Galeazzi and Luigi Galvani got the idea to stimulate frog legs with electrodes. This first step into the world of bioelectronics showed that electronic systems were able to communicate with living organisms through electrical stimulation, as well as by recording electrical signals from organisms. Until the end of the 20th century, the field of bioelectronics kept progressing using metal electrodes. This class of material inherently exhibits a high conductivity from their dispersed cloud of shared electrons. However, an obvious physical mismatch occurs when inserting metal electrodes inside a living organism. Since these materials are not as soft as living tissues, internal damage followed by an immune response impacts the impedance of such probes.In the late 80s', the large-scale commercialization of water processable conducting polymers brought a new paradigm in the choice of electronic material for bioelectronics devices. Compared to metals, conducting polymers are composed of semi-crystalline blocks that interact through electrostatic forces. These soft structures make these materials permeable to aqueous solutions, which allow the introduction of ionic species in the vicinity of the polymer backbone. Ions close to the polymer backbone can tune the conductivity of the material creating a unique ion/electron dialogue that increases the electronic signal resolution. Additionally, these soft structures considerably reduce scaring effects and therefore enable the devices to trigger lower immune responses. Conducting polymers could also be directly inserted within living tissues to create electronic platforms inside a host. Living organisms with new material properties could unravel new functions such as collecting electrophysiological data without surgery.Plants are living organisms that made their way out of the ocean and conquered most of the available land on earth. Saying that plants are good climate controllers is a euphemism since plants are legitimately the organisms that have settled the climate conditions for the development of more advanced life forms. Plant biohybrid is a new technological concept where plants are not only seen for their nutritious or environmental aspect but also as devices that can record and transfer information about their local environmental conditions. Such data could be used in a positive feedback loop to improve the production yield of crops or understand the underlying communication mechanism that occurs between plants or with plant micro-biomes. Most of the approaches toward plant biohybrids nowadays focus on nanomaterials that act as fluorescent probes in leaves and detect analytes from plants' local environment.In this thesis, we push forward a plant biohybrid strategy that instead uses conducting polymers as vectors to build conductors inside plants with the aim to build electrochemical platforms that could be used for applications such as energy storage, sensing, and energy production. Works developed in this thesis are going in an array of directions that aims for the better integration of electronic platforms in living systems with more focus on plants.We first identified a plant enzymatic mechanism that triggers the polymerization of a thiophene oligomer, namely ETE-S in vivo and in vitro. Such plant enzymatic pathways can then be reused to develop electronic systems in plantae without additional reagents. In the next work, we presented the synthesis of three new oligomers called ETE-N, EEE-S, and EEE-N that have a similar architecture compared to ETE-S but with different chemical moieties such as a different ionic side chain or an EDOT instead of thiophene in the middle position of the oligomer. We then demonstrated the effective enzymatic polymerization of these oligomers both in vivo and in vitro and how the resulting polymers' optoelectronic and tissue integrations properties differ. Towards even more versatility, we demonstrated that this electronic integration in vivo was also observed in the case of an animal: the freshwater hydra polyp. The polymerization was observed mostly in differentiated cells from the gastric column of the animal that normally secretes an adhesive used to fix the animal underwater. P(ETE-S) was incorporated in this glue that we managed to characterize using electrochemical methods. Lastly, we performed demonstrations of electrochemical applications with a plant root system. By dipping several roots in an ETE-S solution, we created a network of conducting roots that can effectively store charge as a capacitor with performance comparable to what is classically obtained with conducting polymers. In addition, we modified roots with two different surface modification concepts to make them specific to glucose oxidation: the first method uses a traditional redox hydrogel with a crosslinker and glucose oxidase. The second one uses the embedment of a glucosespecific enzyme inside the p(ETE-S) layer during its formation. These devices are presented as possible new solutions for environmental glucose sensors that could collect current from the environment and store it in neighbouring capacitive roots.Overall, this thesis shows that the enzymatic activity of living systems can be used from an engineering point of view as part of a deposition methods for the development of biohybrid applications.
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| 2. |
- Hantke, Max Felix, 1984-
(författare)
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Coherent Diffractive Imaging with X-ray Lasers
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The newly emerging technology of X-ray free-electron lasers (XFELs) has the potential to revolutionise molecular imaging. XFELs generate very intense X-ray pulses and predictions suggest that they may be used for structure determination to atomic resolution even for single molecules. XFELs produce femtosecond pulses that outrun processes of radiation damage and permit the study of structures at room temperature and of structural dynamics.While the first demonstrations of flash X-ray diffractive imaging (FXI) on biological particles were encouraging, they also revealed technical challenges. In this work we demonstrated how some of these challenges can be overcome. We exemplified, with heterogeneous cell organelles, how tens of thousands of FXI diffraction patterns can be collected, sorted, and analysed in an automatic data processing pipeline. We improved image resolution and reduced problems with missing data. We validated, described, and deposited the experimental data in the Coherent X-ray Imaging Data Bank.We demonstrated that aerosol injection can be used to collect FXI data at high hit ratios and with low background. We reduced problems with non-volatile sample contaminants by decreasing aerosol droplet sizes from ~1000 nm to ~150 nm. We achieved this by adapting an electrospray aerosoliser to the Uppsala sample injector. Mie scattering imaging was used as a diagnostic tool to measure positions, sizes, and velocities of individual injected particles.XFEL experiments generate large amounts of data at high rates. Preparation, execution, and data analysis of these experiments benefits from specialised software. In this work we present new open-source software tools that facilitates prediction, online-monitoring, display, and pre-processing of XFEL diffraction data.We hope that this work is a valuable contribution in the quest of transitioning FXI from its first experimental demonstration into a technique that fulfills its potentials.
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| 3. |
- Johansson, Viktor, 1979-
(författare)
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Dissonant Voices : Philosophy, Children's Literature, and Perfectionist Education
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dissonant Voices has a twofold aspiration. First, it is a philosophical treatment of everyday pedagogical interactions between children and their elders, between teachers and pupils. More specifically it is an exploration of the possibilities to go on with dissonant voices that interrupt established practices – our attunement – in behaviour, practice and thinking. Voices that are incomprehensible or expressions that are unacceptable, morally or otherwise. The text works on a tension between two inclinations: an inclination to wave off, discourage, or change an expression that is unacceptable or unintelligible; and an inclination to be tolerant and accept the dissonant expression as doing something worthwhile, but different.The second aspiration is a philosophical engagement with children’s literature. Reading children’s literature becomes a form of philosophising, a way to explore the complexity of a range of philosophical issues. This turn to literature marks a dissatisfaction with what philosophy can accomplish through argumentation and what philosophy can do with a particular and limited set of concepts for a subject, such as ethics. It is a way to go beyond philosophising as the founding of theories that justify particular responses. The philosophy of dissonance and children’s literature becomes a way to destabilise justifications of our established practices and ways of interacting.The philosophical investigations of dissonance are meant to make manifest the possibilities and risks of engaging in interactions beyond established agreement or attunements. Thinking of the dissonant voice as an expression beyond established practices calls for improvisation. Such improvisations become a perfectionist education where both the child and the elder, the teacher and the student, search for as yet unattained forms of interaction and take responsibility for every word and action of the interaction.The investigation goes through a number of picture books and novels for children such as Harry Potter, Garmann’s Summer, and books by Shaun Tan, Astrid Lindgren and Dr. Seuss as well narratives by J.R.R. Tolkien, Henrik Ibsen, Jane Austen and Henry David Thoreau. These works of fiction are read in conversation with philosophical works of, and inspired by, Ludwig Wittgenstein and Stanley Cavell, their moral perfectionism and ordinary language philosophy.
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| 5. |
- Muchowski, Julia C., 1989-
(författare)
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Uncovering Ocean Mixing near Rough Bathymetry : Using Broadband Acoustics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ocean mixing related to rough bathymetry is highly dynamic and exhibits large spatial and temporal variability. Therefore, established in-situ methods as well as numerical models often lack the resolution to capture this type of mixing. In this thesis, acoustics are used to observe, map and quantify stratified mixing at unprecedented resolution. Acoustic broadband data from a Simrad EK80 and co-located microstructure data from a Sea & Sun Technology MicroStructure profiler (MSS) were collected during two cruises on R/V Electra in Feb-March 2019 and 2020 in the Southern Quark region in the northern Åland Sea, Baltic Sea. In the first manuscript (M1), an existing acoustic model to quantify turbulent mixing from acoustic backscatter is revisited and applied to the co-located data sets. Possibilities and limitations of applying the acoustic model are investigated in detail. In a following case study (M2), the acoustic model is applied to a subset of the data where rough bathymetry reaches into stratified flow and highly increases mixing across the halocline. The dominant mixing mechanism is revealed to be wake vortices and their impact is estimated using a diffusion model. The final case study (M3) emphasizes the impact of mixing in the Southern Quark on exchange processes between the distinctly different Northern Baltic Proper and the Bothnian Sea. The acoustic observations uncover the detailed structure (M1-M3) and temporal development (M3) of turbulent diapycnal mixing in heterogeneous flow over rough bathymetry. This thesis is a step towards increased applicability and automatized analysis of acoustic broadband data for identifying and quantifying turbulent diapycnal mixing.
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