1,324 research outputs found

    Synthesis of Crosslinked Block Copolymer Microparticles in Supercritical CO2

    Get PDF
    To this end, this work aims to develop a synthesis route to structured cross-linked BCP microparticles, with different size and morphology, by RAFT-dispersion polymerisation in scCO2. It is also essential that the developed method can preserve the microparticulate and internal nanostructure integrity, particularly in solvated environment. This study, which focuses on poly(methyl methacrylate)-block-poly(4-vinyl pyridine) (PMMA-b-P4VP) BCP with spherical (SPH) and lamellar (LAM) morphology, has been successful in crosslinking the BCP with divinyl benzene (DVB), ranging from 0 to 16 wt.%. The microparticle structure and the internal morphology is maintained by delaying the addition of the crosslinker and a portion of the second monomer. As a result polymerisation induced microphase separation within the microparticles is well maintained while the growing chains of the precursor PMMA-b-P4VP microparticles are crosslinked. The internal structures formed in the synthesised products were fully characterised by multiple instrumental techniques and promising results were revealed. The swelling and solubility behaviour of the crosslinked microparticles exhibiting either SPH or LAM internal morpholody was investigated via microscopy techniques including Tilt-TEM tomography and nitrogen adsorption isotherm. The maximum resistance point to swelling for both the SPH and LAM BCP microparticles were determined. The SPH microparticles incorporating different levels of crosslinking were found to have control over the porosity formation when swollen in ethanol. Macropores greater than 100 nm, mesopores 20 nm, sub-10 nm pores, and finally non-porous structures were all obtained by increasing the DVB concentration from 0 to 0.5, 1, and 4 wt.%, respectively. It was demonstrated that the size and porosity of the microparticle BCP can be controlled through in-situ crosslinking copolymerisation by RAFT-dispersion in scCO2. This control allows for tuning of the materials for different applications. Both the non-porous SPH (synthesised using 2.5 wt.% PDMS-MA) and the LAM particles demonstrated good potential as an enzyme support, by recording an immobilisation yield of more than 50 % during lipase immobilisation. Amongst the tested samples, the porous particles synthesised with 5 wt.% PDMS-MA and 1 wt.% crosslinker recorded the highest adsorption yield of usnic acid (79%). The extraction capacity of the majority of the microparticles synthesis using 2.5 wt.% PDMS-MA and DVB concentration ranging from 0-4 wt.% was found satisfactory for polymer stationary phase application, with the percentage of recovery meeting the estimated specification (35 to 75 %)

    Characterising the neck motor system of the blowfly

    Get PDF
    Flying insects use visual, mechanosensory, and proprioceptive information to control their movements, both when on the ground and when airborne. Exploiting visual information for motor control is significantly simplified if the eyes remain aligned with the external horizon. In fast flying insects, head rotations relative to the body enable gaze stabilisation during highspeed manoeuvres or externally caused attitude changes due to turbulent air. Previous behavioural studies into gaze stabilisation suffered from the dynamic properties of the supplying sensor systems and those of the neck motor system being convolved. Specifically, stabilisation of the head in Dipteran flies responding to induced thorax roll involves feed forward information from the mechanosensory halteres, as well as feedback information from the visual systems. To fully understand the functional design of the blowfly gaze stabilisation system as a whole, the neck motor system needs to be investigated independently. Through X-ray micro-computed tomography (ÎŒCT), high resolution 3D data has become available, and using staining techniques developed in collaboration with the Natural History Museum London, detailed anatomical data can be extracted. This resulted in a full 3- dimensional anatomical representation of the 21 neck muscle pairs and neighbouring cuticula structures which comprise the blowfly neck motor system. Currently, on the work presented in my PhD thesis, ÎŒCT data are being used to infer function from structure by creating a biomechanical model of the neck motor system. This effort aims to determine the specific function of each muscle individually, and is likely to inform the design of artificial gaze stabilisation systems. Any such design would incorporate both sensory and motor systems as well as the control architecture converting sensor signals into motor commands under the given physical constraints of the system as a whole.Open Acces

    2015 GREAT Day Program

    Get PDF
    SUNY Geneseo’s Ninth Annual GREAT Day.https://knightscholar.geneseo.edu/program-2007/1009/thumbnail.jp

    Reference Frames in Human Sensory, Motor, and Cognitive Processing

    Get PDF
    Reference-frames, or coordinate systems, are used to express properties and relationships of objects in the environment. While the use of reference-frames is well understood in physical sciences, how the brain uses reference-frames remains a fundamental question. The goal of this dissertation is to reach a better understanding of reference-frames in human perceptual, motor, and cognitive processing. In the first project, we study reference-frames in perception and develop a model to explain the transition from egocentric (based on the observer) to exocentric (based outside the observer) reference-frames to account for the perception of relative motion. In a second project, we focus on motor behavior, more specifically on goal-directed reaching. We develop a model that explains how egocentric perceptual and motor reference-frames can be coordinated through exocentric reference-frames. Finally, in a third project, we study how the cognitive system can store and recognize objects by using sensorimotor schema that allows mental rotation within an exocentric reference-frame

    A discursive analysis of post-16 females' stories of educational reintegration and non attendance experiences

    Get PDF
    Emotionally-based school avoidance (EBSA) is associated with significant negative social, academic, and health outcomes for young people and their families. Female adolescents from marginalised backgrounds, including those with diagnosed mental health conditions, are more likely to experience EBSA and school absences. Rates of persistent non attendance are continuing to rise, highlighting the need to understand how to effectively support adolescents to remain and reengage in education. This study presents the experiences of four female post-16 students who have experienced persistent non-attendance in secondary school. They have since returned to education and now attend college on a full-time basis. The study used discursive psychology to analyse participants’ discourses to gain an understanding of their attendance experiences. Data was gathered through an initial narrative interview. Participants structured their retrospective narratives by using life charts (Moyse, 2021) and engaged in a second interview in which they were requested to bring a non-verbal representation of their educational experiences. Participant narratives are structured and framed in relation to two theoretical frameworks that have been applied to promote attendance: the systems view of school climate (SVSC) (Rudasill et al., 2018) and the persistent educational absence and reengagement with learning and school (PEARLS) model (Baron Williams, 2021). Consideration was also given to how participants used discourse to position themselves and construct their emotions, the impact of COVID and chosen personal connection items (non-verbal representations) were also considered. The study highlights the use of a multi-tiered systems approach to promote attendance within educational settings and outlines the role of the educational psychologist (EP) within these processes. The findings emphasise the importance of relationships and emotional validation within educational environments. Participants mainly cited environmental strategies as effective in supporting them with their non-attendance. The study concludes by discussing the implications of the research for educational psychology practice, local authorities, and educational settings

    Sourcing high tissue quality brains from deceased wild primates with known socio‐ecology

    Get PDF
    The selection pressures that drove dramatic encephalisation processes through the mammal lineage remain elusive, as does knowledge of brain structure reorganisation through this process. In particular, considerable structural brain changes are present across the primate lineage, culminating in the complex human brain that allows for unique behaviours such as language and sophisticated tool use. To understand this evolution, a diverse sample set of humans' closest relatives with varying socio-ecologies is needed. However, current brain banks predominantly curate brains from primates that died in zoological gardens. We try to address this gap by establishing a field pipeline mitigating the challenges associated with brain extractions of wild primates in their natural habitat. The success of our approach is demonstrated by our ability to acquire a novel brain sample of deceased primates with highly variable socio-ecological exposure and a particular focus on wild chimpanzees. Methods in acquiring brain tissue from wild settings are comprehensively explained, highlighting the feasibility of conducting brain extraction procedures under strict biosafety measures by trained veterinarians in field sites. Brains are assessed at a fine-structural level via high-resolution MRI and state-of-the-art histology. Analyses confirm that excellent tissue quality of primate brains sourced in the field can be achieved with a comparable tissue quality of brains acquired from zoo-living primates. Our field methods are noninvasive, here defined as not harming living animals, and may be applied to other mammal systems than primates. In sum, the field protocol and methodological pipeline validated here pose a major advance for assessing the influence of socio-ecology on medium to large mammal brains, at both macro- and microstructural levels as well as aiding with the functional annotation of brain regions and neuronal pathways via specific behaviour assessments.Output Status: Forthcoming/Available Online Additional authors: Richard McElreath, Alfred Anwander, Philipp Gunz, Markus Morawski, Angela D. Friederici, Nikolaus Weiskopf, Fabian H. Leendertz, Roman M. Wittig EBC Cosortium: Karoline Albig, Bala Amarasekaran, Sam Angedakin, Alfred Anwander, Daniel Aschoff, Caroline Asiimwe, Laurent Bailanda, Jacinta C. Beehner, Raphael Belais, Thore J. Bergman, Birgit Blazey, Andreas Bernhard, Christian Bock, PĂ©nĂ©lope Carlier, Julian Chantrey, Catherine Crockford, Tobias Deschner, Ariane DĂŒx1, Luke Edwards, Cornelius Eichner, GĂ©raldine Escoubas2, Malak Ettaj, Karina Flores, Richard Francke, Angela D. Friederici, CĂ©dric Girard-Buttoz, Jorge Gomez Fortun, Zoro Bertin GoneBi, Tobias GrĂ€ĂŸle, Eva Gruber-Dujardin, Philipp Gunz, Jess Hartel, Daniel B. M. Haun, Michael Henshall, Catherine Hobaiter, NoĂ©mie Hofman, Jenny E. Jaffe, Carsten JĂ€ger, Anna Jauch, Stomy Kahemere, Evgeniya Kirilina, Robert Klopfleisch, Tobias Knauf-Witzens, Kathrin S. Kopp, Guy Landry Mamboundou Kouima, Bastian Lange, Kevin Langergraber, Arne Lawrenz, Fabian H. Leendertz, Ilona Lipp, Matys Liptovszky, Tobias Loubser Theron, Christelle Patricia Lumbu, Patrice Makouloutou Nzassi, Kerstin MĂ€tz-Rensing, Richard McElreath, Matthew McLennan, Zoltan Mezö, Sophie Moittie, Torsten MĂžller, Markus Morawski, David Morgan, Timothy Mugabe, Martin Muller, Matthias MĂŒller, Inoussa Njumboket, Karin Olofsson-Sannö, Alain Ondzie, Emily Otali, Michael Paquette, Simone Pika, Kerrin Pine, Andrea Pizarro, Kamilla PlĂ©h, Jessica Rendel, Sandra Reichler-Danielowski, Martha M. Robbins, Alejandra Romero Forero, Konstantin Ruske, Liran Samuni, Crickette Sanz, AndrĂ© SchĂŒle, Ingo Schwabe, Katarina Schwalm, Sheri Speede, Lara Southern, Jonas Steiner, Marc Stidworthy, Martin Surbeck, Claudia Szentiks, Tanguy Tanga, Reiner Ulrich, Steve Unwin, Erica van de Waal, Sue Walker, Nikolaus Weiskopf, Gudrun Wibbelt, Roman M. Wittig, Kim Wood, Klaus ZuberbĂŒhle
    • 

    corecore