Browsing by Subject "Physics"

Now showing 1 - 6 of 6
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    Developing an approach to improve beta-phase properties in ferroelectric pvd-hfp thin films
    (2020-05) Dale, Ashley S.; Cheng, Ruihua; Petrache, Horia; Wassall, Stephen
    Improved fabrication of poly(vinylindenefluoride)-hexafluoropropylene (PVDF-HFP) thin films is of particular interest due to the high electric coercivity found in the beta-phase structure of the thin film. We show that it is possible to obtain high-quality, beta-phase dominant PVDF-HFP thin films using a direct approach to Langmuir-Blodgett deposition without the use of annealing or additives. To improve sample quality, an automated Langmuir-Blodgett thin film deposition system was developed; a custom dipping trough was fabricated, a sample dipping mechanism was designed and constructed, and the system was automated using custom LabVIEW software. Samples were fabricated in the form of ferroelectric capacitors on substrates of glass and silicon, and implement a unique step design with a bottom electrode of copper with an aluminum wetting layer and a top electrode of gold with an aluminum wetting layer. Samples were then characterized using a custom ferroelectric measurement program implemented in LabVIEW with a Keithley picoammeter/voltage supply to confirm electric coercivity properties. Further characterization using scanning electron microscopy and atomic force microscopy confirmed the improvement in thin film fabrication over previous methods.
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    Elucidating the complex organization of neural micro-domains in the locust Schistocerca gregaria using dMRI
    (Springer Nature, 2021-02-09) Shahid, Syed Salman; Kerskens, Christian M.; Burrows, Malcolm; Witney, Alice G.; Radiology and Imaging Sciences, School of Medicine
    To understand brain function it is necessary to characterize both the underlying structural connectivity between neurons and the physiological integrity of these connections. Previous research exploring insect brain connectivity has typically used electron microscopy techniques, but this methodology cannot be applied to living animals and so cannot be used to understand dynamic physiological processes. The relatively large brain of the desert locust, Schistercera gregaria (Forksȧl) is ideal for exploring a novel methodology; micro diffusion magnetic resonance imaging (micro-dMRI) for the characterization of neuronal connectivity in an insect brain. The diffusion-weighted imaging (DWI) data were acquired on a preclinical system using a customised multi-shell diffusion MRI scheme optimized to image the locust brain. Endogenous imaging contrasts from the averaged DWIs and Diffusion Kurtosis Imaging (DKI) scheme were applied to classify various anatomical features and diffusion patterns in neuropils, respectively. The application of micro-dMRI modelling to the locust brain provides a novel means of identifying anatomical regions and inferring connectivity of large tracts in an insect brain. Furthermore, quantitative imaging indices derived from the kurtosis model that include fractional anisotropy (FA), mean diffusivity (MD) and kurtosis anisotropy (KA) can be extracted. These metrics could, in future, be used to quantify longitudinal structural changes in the nervous system of the locust brain that occur due to environmental stressors or ageing.
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    First In-Human Burst Wave Lithotripsy for Kidney Stone Comminution: Initial Two Case Studies
    (Mary Ann Liebert, Inc., 2021) Harper, Jonathan D.; Metzler, Ian; Hall, Michael Kennedy; Chen, Tony T.; Maxwell, Adam D.; Cunitz, Bryan W.; Dunmire, Barbrina; Thiel, Jeff; Williams, James C., Jr.; Bailey, Michael R.; Sorensen, Mathew D.; Anatomy, Cell Biology and Physiology, School of Medicine
    Purpose: To test the effectiveness (Participant A) and tolerability (Participant B) of urinary stone comminution in the first-in-human trial of a new technology, burst-wave lithotripsy (BWL). Materials and Methods: An investigational BWL and ultrasonic propulsion system was used to target a 7-mm kidney stone in the operating room before ureteroscopy (Participant A). The same system was used to target a 7.5 mm ureterovesical junction stone in clinic without anesthesia (Participant B). Results: For Participant A, a ureteroscope inserted after 9 minutes of BWL observed fragmentation of the stone to <2 mm fragments. Participant B tolerated the procedure without pain from BWL, required no anesthesia, and passed the stone on day 15. Conclusions: The first-in-human tests of BWL pulses were successful in that a renal stone was comminuted in <10 minutes, and BWL was also tolerated by an awake subject for a distal ureteral stone.
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    Observation of slowly decaying eigenmodes without exceptional points in Floquet dissipative synthetic circuits
    (Springer Nature, 2018-12-03) León-Montiel, Roberto de J.; Quiroz-Juárez, Mario A.; Domínguez-Juárez, Jorge L.; Quintero-Torres, Rafael; Aragón, José L.; Harter, Andrew K.; Joglekar, Yogesh N.; Physics, School of Science
    Parity-time symmetric systems allow one to study new types of Hamiltonians which could have potential impact on our understanding of nonlinear physics. The authors investigate the energy stored in an electronic Floquet system and demonstrate that such a setup can be used to study the dynamics of dissipative parity-time symmetric systems.
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    Thermoplastic polyurethane flexible capacitive proximity sensor reinforced by CNTs for applications in the creative industries
    (Springer Nature, 2021-01-13) Moheimani, Reza; Aliahmad, Nojan; Aliheidari, Nahal; Agarwal, Mangilal; Dalir, Hamid; Mechanical and Energy Engineering, School of Engineering and Technology
    Wearable sensing platforms have been rapidly advanced over recent years, thanks to numerous achievements in a variety of sensor fabrication techniques. However, the development of a flexible proximity sensor that can perform in a large range of object mobility remains a challenge. Here, a polymer-based sensor that utilizes a nanostructure composite as the sensing element has been presented for forthcoming usage in healthcare and automotive applications. Thermoplastic Polyurethane (TPU)/Carbon Nanotubes (CNTs) composites are capable of detecting presence of an external object in a wide range of distance. The proximity sensor exhibits an unprecedented detection distance of 120 mm with a resolution of 0.3%/mm. The architecture and manufacturing procedures of TPU/CNTs sensor are straightforward and performance of the proximity sensor shows robustness to reproducibility as well as excellent electrical and mechanical flexibility under different bending radii and over hundreds of bending cycles with variation of 4.7% and 4.2%, respectively. Tunneling and fringing effects are addressed as the sensing mechanism to explain significant capacitance changes. Percolation threshold analysis of different TPU/CNT contents indicated that nanocomposites having 2 wt% carbon nanotubes are exhibiting excellent sensing capabilities to achieve maximum detection accuracy and least noise among others. Fringing capacitance effect of the structure has been systematically analyzed by ANSYS Maxwell (Ansoft) simulation, as the experiments precisely supports the sensitivity trend in simulation. Our results introduce a new mainstream platform to realize an ultrasensitive perception of objects, presenting a promising prototype for application in wearable proximity sensors for motion analysis and artificial electronic skin.
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    When science gets ugly – the story of Philipp Lenard and Albert Einstein
    (The Conversation US, Inc., 2015-06-16) Gunderman, Richard; Radiology and Imaging Sciences, School of Medicine