8 research outputs found

    A machine learning‑based image segmentation method to quantify in vitro osteoclast culture endpoints

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    Quantification of in vitro osteoclast cultures (e.g. cell number) often relies on manual counting methods. These approaches are labour intensive, time consuming and result in substantial inter- and intra-user variability. This study aimed to develop and validate an automated workflow to robustly quantify in vitro osteoclast cultures. Using ilastik, a machine learning-based image analysis software, images of tartrate resistant acid phosphatase-stained mouse osteoclasts cultured on dentine discs were used to train the ilastik-based algorithm. Assessment of algorithm training showed that osteoclast numbers strongly correlated between manual- and automatically quantified values (r = 0.87). Osteoclasts were consistently faithfully segmented by the model when visually compared to the original reflective light images. The ability of this method to detect changes in osteoclast number in response to different treatments was validated using zoledronate, ticagrelor, and co-culture with MCF7 breast cancer cells. Manual and automated counting methods detected a 70% reduction (p < 0.05) in osteoclast number, when cultured with 10 nM zoledronate and a dose-dependent decrease with 1-10 μM ticagrelor (p < 0.05). Co-culture with MCF7 cells increased osteoclast number by ≥ 50% irrespective of quantification method. Overall, an automated image segmentation and analysis workflow, which consistently and sensitively identified in vitro osteoclasts, was developed. Advantages of this workflow are (1) significantly reduction in user variability of endpoint measurements (93%) and analysis time (80%); (2) detection of osteoclasts cultured on different substrates from different species; and (3) easy to use and freely available to use along with tutorial resources

    Interplay of Nanostructure and Molecular Doping of Poly(3-hexylthiophene)

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    The accelerating growth of the number of inter-connected small devices, which together make up the so-called Internet of Things, is increasing the need for autonomous power sources. Heat is an abundant and often wasted source of energy. Thermoelectric generators could be used to harvest this waste energy. Small devices could potentially be powered by low-grade heat sources using flexible plastic thermoelectric generators.This thesis discusses thermoelectric plastics and in particular the semiconducting polymer poly(3-hexylthiophene) (P3HT). P3HT is a model conjugated polymer that is commercially available and has become an important reference material for the study of optoelectronic processes in organic semiconductors.At first, I investigated isotropic thin films of P3HT doped with 2,3,5,6-Tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ). I chose doping from the vapour phase as this allowed me to disentangle the influence of polymer processing and doping. I demonstrate that by improving the degree of solid state order of P3HT it is possible to strongly increase the electrical conductivity, which enhances the thermoelectric power factor from 0.2 to 2.7 μW m-1 K-2.Secondly, I explored the impact of orientation on the thermoelectric properties of P3HT. I chose to study highly anisotropic thin films of P3HT, aligned using a high temperature rubbing technique. Further, I investigated free-standing bulk tapes that where uniaxially oriented through tensile drawing. Sequential doping from solution with F4TCNQ or a molybdenum dithiolene complex allowed me to preserve the anisotropy of both thin films and stretched tapes. I found that orientation of the polymer allows to further increase the thermoelectric properties in the direction of alignment. As a result, a power factor of 16 μW m-1 K-2 for tensile drawn tapes and ~ 100 μW m-1 K-2 for rubbed thin films is obtained. Furthermore, oriented P3HT tapes show no change in the glass transition temperature of about 20 C upon doping with a molybdenum dithiolene complex, which suggests that tensile drawing can be used to prepare flexible thermoelectric materials

    Crystal Chemistry, Elastic Properties and Melting Behaviors of Iron-Bearing Materials in Earth and Planetary Interiors.

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    Iron (Fe), with the maximal nuclear stability, is the most abundant element in the Earth. With a partially filled 3d shell, iron adds a variety of influences onto the physical properties and chemical behavior of the Earth and planetary interiors. This dissertation addresses a number of issues concerning the nature and dynamics of the Earth lower mantle and the terrestrial cores. In research chapter I, I studied the crystal chemistry of lower mantle bridgmanite by temperature dependent Mössbauer spectra. I inferred the site occupancy of Fe2+ and Fe3+ in a large number of bridgmanite samples reported in the literature and offered new insights into the crystal chemistry, spin states and electric conduction mechanisms in bridgmanite. In research chapter II, I measured lattice parameters of Fe7C3 at 300 K and up to 68 GPa. Two discontinuities were found in the compression curve, which can be attributed to ferromagnetic to paramagnetic transition and paramagnetic to nonmagnetic transition, respectively. By extrapolating the established equations-of-state to the inner core pressure-temperature conditions, the nonmagnetic phase provides a good match for the observed density of the inner core, whereas the paramagnetic phase would be denser by 12~13 %. In research chapter III, I proposed a new mechanism to explain the nonubiquitous occurrence of ultra-low velocity zones based on my eutectic melting curve of Fe-C system: About 1 wt.% mixture of iron and diamond/iron carbide could be generated in subducted oceanic lithosphere when penetrating the 660 km discontinuity. Such mixture would melt in the basal part of the lower mantle and significantly lower seismic velocities. In research chapter IV, I investigated the melting behaviors of iron-nickel-sulfur system at the pressure of the lunar inner-core boundary (5.1 GPa). Based on my data, I proposed that lunar core with 5.4 ~ 11.3 wt.% sulfur would start to crystallize in the center and support a long-lived lunar dynamo; due to the growth of the inner core, the crystallization of such lunar core would switch to take place at the top of the core and the lunar dynamo is expected to shut down shortly afterwards.PHDGeologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/111628/1/jiacliu_1.pd


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    Marien, C., Dijkstra, A.H. and Wilkins, C., 2018. The hydrothermal alteration of carbonatite in the Fen Complex, Norway: mineralogy, geochemistry, and implications for rare-earth element resource formation. Mineralogical Magazine, 82(S1): S115-S131.The Fen Complex in Norway consists of a composite carbonatite-ijolite-pyroxenite diatreme intrusion. Locally, the hydrothermally altered, hematite-rich rock rødbergite exhibited high grades (up to 2.1 wt% REE) of rare earth elements (REE). In order to secure the supply of REE for future technology markets in Europe, it becomes increasingly important to establish potential domestic REE sources like the Fen Complex. This project aims to develop a model for the carbonatite-hosted hydrothermal REE deposit (‘Rødbergite’) in the Fen Complex, Norway. SEM and ICP-MS trace element analyses of 73 bulk samples taken along various geological key transects showed the transformation of carbonatite, damtjernite, gneiss and fenite to rødbergite. An alteration mineral assemblage of dolomite, Fe-dolomite, barite, Ba-bearing phlogopite, hematite with accessory apatite, calcite, monazite-(Ce) and quartz replaced the original minerals of the protolith. The transformation to rødbergite is accompanied by an increase in REE concentrations (up to 23-fold) — mainly light REE— and Th. The overall REE concentration of rødbergite varies strongly and depends on the REE concentration of the protolith, density of hydrothermal micro-veins — containing monazite, bastnäsite, synchysite and allanite — and locally apatite relics. While Th-Pb geochronology of zircons established a robust age for the emplacement of the Fen Complex carbonatite with 550 Ma ± 10 Ma, monazite from rødbergite gave U-Pb and Th-Pb ages of 272 Ma ± 5 Ma and 272 Ma ± 10 Ma respectively. The age of the REE-mineralisation coincides with the Oslo rift formation, which is interpreted as the heat source triggering the hydrothermal formation of rødbergite at the Fen Complex The major findings are combined in a new ore deposit model for rødbergite that can help to improve exploration strategies in the Fen complex and has implications for carbonatite-hosted hydrothermal REE resources around the world.NERC Isotope Geosciences Facilities Steering Committe

    Nanodroplet-Mediated Electrodeposition: Fundamental Principles and Applications to Nanomaterial Synthesis

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    The electrodeposition of metallic phases, also known as electroplating, has been rigorously studied since its inception in 1805, yielding a great deal of fundamental knowledge and numerous practical products (e.g., corrosion-resistant coatings, catalysts, and consumer goods). Following the nano-revolution in the mid-20th century, prodigious resources have been devoted to control the surface coverage, size, and elemental composition of metal nanoparticles, which represent the functional unit of an electrodeposited film. These efforts aim to overcome the tendency for nanoparticles to nucleate and grow on energetically favorable surface sites, diffusion-layer overlap between neighboring particles, and variation in ion reduction kinetics, phenomena which result in coverage, size, and stochiometric heterogeneity, respectively. This dissertation describes a method termed nanodroplet-mediated electrodeposition¬, wherein the electrodeposition reaction is confined within single aqueous nanodroplets. By emulsifying precursor-loaded aqueous nanodroplets into an immiscible solvent such as 1,2-dichloroethane, nano-reactors may be generated which, upon collision with an electrode surface, undergo electrodeposition to form single nanoparticles with relative control over coverage and size compared to classical electrodeposition. The addition of a viscous component (e.g., glycerol) to the nano-reactors permits the quantification of single nanoparticle growth kinetics as the electrochemical signal is monitored using stochastic collisions at ultramicroelectrodes. Furthermore, the addition of multiple metal precursors to the nano-reactors allows multi-metallic high-entropy nanomaterials to be synthesized, which may be practically applied for bifunctional water electrolysis. Thus, novel fundamental knowledge and practical materials have been generated by this method, highlighting its promise to elucidate new and useful truths of nature in the near future.Doctor of Philosoph

    Structure, emplacement and textural evolution of young obsidian lavas in the Aeolian Islands, Italy

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    Silicic volcanism defines the recent volcanic activity in the Aeolian Islands, Italy. Such activity on the islands of Lipari and Vulcano has generally involved an explosive phase, ending with viscous lava extrusion and a period of quiescence. This late effusive extrusion has resulted in a number of obsidian lava flows and domes. Obsidian lavas on Lipari and Vulcano are texturally heterogeneous, and many of the young lava flows show signs of flow deformation associated with flow emplacement. Preservation of such textures and structures is important for the reconstruction of the structural and textural evolution of young obsidian lava flows, in the Aeolian Islands lavas and elsewhere. Models of emplacement of obsidian lavas are still relatively limited, and there is still a need for a detailed model for obsidian lava flow emplacement. Questions also remain regarding spherulite formation in obsidian lavas, including when spherulites begin to form, over what timescale, and their relationship to deformation. Obsidian flows on Lipari and Vulcano exhibit a number of textures relating to both magmatic and post-magmatic processes. These textures provide an opportunity to build a model that categorises textural evolution in an active volcanic setting. This study incorporates a number of petrographic, geochemical and textural methods in order to fully characterise the structure, emplacement and textural evolution of young obsidian lavas in the Aeolian Islands. The findings contribute towards our understanding of silicic volcanism in the Aeolian Islands, our overall understanding of obsidian lava flow emplacement and spherulite formation, and the complex structural and textural relationships within obsidian lavas

    File 9: Robust laser ablation Lu–Hf dating of apatite: an empirical evaluation

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    Thin section microphotographs from the Taratap Granodiorite. (A) Apatite cogenetic with allanite. (B) Apatite overgrown by monazite. (C, D) Titanite in chlorite ((C) transmitted light image; (D) reflective light image; circle symbols are laser ablation spots)