7,819 research outputs found

    Inkjet printed flexible non-enzymatic glucose sensor for tear fluid analysis

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    © 2017 Here, we present a flexible and low-cost inkjet printed electrochemical sensor for enzyme-free glucose analysis. Versatility, short fabrication time and low cost make inkjet printing a valuable alternative to traditional sensor manufacturing techniques. We fabricated electro-chemical glucose sensors by inkjet printing electrodes on a flexible polyethylene terephthalate substrate. CuO microparticles were used to modify our electrodes, leading to a sensitive, stable and cost-effective platform for non-enzymatic detection of glucose. Selectivity, reproducibility, and life-time provided by the CuO functionalization demonstrated that these sensors are reliable tools for personalized diagnostics and self-assessment of an individual's health. The detection of glucose at concentrations matching that of tear fluid allows us to envisage applications in ocular diagnostics, where painless and non-invasive monitoring of diabetes can be achieved by analyzing glucose contained in tears

    Towards A Graphene Chip System For Blood Clotting Disease Diagnostics

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    Point of care diagnostics (POCD) allows the rapid, accurate measurement of analytes near to a patient. This enables faster clinical decision making and can lead to earlier diagnosis and better patient monitoring and treatment. However, despite many prospective POCD devices being developed for a wide range of diseases this promised technology is yet to be translated to a clinical setting due to the lack of a cost-eïŹ€ective biosensing platform.This thesis focuses on the development of a highly sensitive, low cost and scalable biosensor platform that combines graphene with semiconductor fabrication tech-niques to create graphene ïŹeld-eïŹ€ect transistors biosensor. The key challenges of designing and fabricating a graphene-based biosensor are addressed. This work fo-cuses on a speciïŹc platform for blood clotting disease diagnostics, but the platform has the capability of being applied to any disease with a detectable biomarker.Multiple sensor designs were tested during this work that maximised sensor ef-ïŹciency and costs for diïŹ€erent applications. The multiplex design enabled diïŹ€erent graphene channels on the same chip to be functionalised with unique chemistry. The Inverted MOSFET design was created, which allows for back gated measurements to be performed whilst keeping the graphene channel open for functionalisation. The Shared Source and Matrix design maximises the total number of sensing channels per chip, resulting in the most cost-eïŹ€ective fabrication approach for a graphene-based sensor (decreasing cost per channel from ÂŁ9.72 to ÂŁ4.11).The challenge of integrating graphene into a semiconductor fabrication process is also addressed through the development of a novel vacuum transfer method-ology that allows photoresist free transfer. The two main fabrication processes; graphene supplied on the wafer “Pre-Transfer” and graphene transferred after met-allisation “Post-Transfer” were compared in terms of graphene channel resistance and graphene end quality (defect density and photoresist). The Post-Transfer pro-cess higher quality (less damage, residue and doping, conïŹrmed by Raman spec-troscopy).Following sensor fabrication, the next stages of creating a sensor platform involve the passivation and packaging of the sensor chip. DiïŹ€erent approaches using dielec-tric deposition approaches are compared for passivation. Molecular Vapour Deposi-tion (MVD) deposited Al2O3 was shown to produce graphene channels with lower damage than unprocessed graphene, and also improves graphene doping bringing the Dirac point of the graphene close to 0 V. The packaging integration of microïŹ‚uidics is investigated comparing traditional soft lithography approaches and the new 3D printed microïŹ‚uidic approach. SpeciïŹc microïŹ‚uidic packaging for blood separation towards a blood sampling point of care sensor is examined to identify the laminar approach for lower blood cell count, as a method of pre-processing the blood sample before sensing.To test the sensitivity of the Post-Transfer MVD passivated graphene sensor de-veloped in this work, real-time IV measurements were performed to identify throm-bin protein binding in real-time on the graphene surface. The sensor was function-alised using a thrombin speciïŹc aptamer solution and real-time IV measurements were performed on the functionalised graphene sensor with a range of biologically relevant protein concentrations. The resulting sensitivity of the graphene sensor was in the 1-100 pg/ml concentration range, producing a resistance change of 0.2% per pg/ml. SpeciïŹcity was conïŹrmed using a non-thrombin speciïŹc aptamer as the neg-ative control. These results indicate that the graphene sensor platform developed in this thesis has the potential as a highly sensitive POCD. The processes developed here can be used to develop graphene sensors for multiple biomarkers in the future

    Synthesis and Characterisation of Low-cost Biopolymeric/mineral Composite Systems and Evaluation of their Potential Application for Heavy Metal Removal

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    Heavy metal pollution and waste management are two major environmental problems faced in the world today. Anthropogenic sources of heavy metals, especially effluent from industries, are serious environmental and health concerns by polluting surface and ground waters. Similarly, on a global scale, thousands of tonnes of industrial and agricultural waste are discarded into the environment annually. There are several conventional methods to treat industrial effluents, including reverse osmosis, oxidation, filtration, flotation, chemical precipitation, ion exchange resins and adsorption. Among them, adsorption and ion exchange are known to be effective mechanisms for removing heavy metal pollution, especially if low-cost materials can be used. This thesis was a study into materials that can be used to remove heavy metals from water using low-cost feedstock materials. The synthesis of low-cost composite matrices from agricultural and industrial by-products and low-cost organic and mineral sources was carried out. The feedstock materials being considered include chitosan (generated from industrial seafood waste), coir fibre (an agricultural by-product), spent coffee grounds (a by-product from coffee machines), hydroxyapatite (from bovine bone), and naturally sourced aluminosilicate minerals such as zeolite. The novel composite adsorbents were prepared using commercially sourced HAp and bovine sourced HAp, with two types of adsorbents being synthesized, including two- and three-component composites. Standard synthetic methods such as precipitation were developed to synthesize these materials, followed by characterization of their structural, physical, and chemical properties (by using FTIR, TGA, SEM, EDX and XRD). The synthesized materials were then evaluated for their ability to remove metal ions from solutions of heavy metals using single-metal ion type and two-metal ion type solution systems, using the model ion solutions, with quantification of their removal efficiency. It was followed by experimentation using the synthesized adsorbents for metal ion removal in complex systems such as an industrial input stream solution system obtained from a local timber treatment company. Two-component composites were considered as control composites to compare the removal efficiency of the three-component composites against. The heavy metal removal experiments were conducted under a range of experimental conditions (e.g., pH, sorbent dose, initial metal ion concentration, time of contact). Of the four metal ion systems considered in this study (Cd2+, Pb2+, Cu2+ and Cr as chromate ions), Pb2+ ion removal by the composites was found to be the highest in single-metal and two-metal ion type solution systems, while chromate ion removal was found to be the lowest. The bovine bone-based hydroxyapatite (bHAp) composites were more efficient at removing the metal cations than composites formed from a commercially sourced hydroxyapatite (cHAp). In industrial input stream solution systems (containing Cu, Cr and As), the Cu2+ ion removal was the highest, which aligned with the observations recorded in the single and two-metal ion type solution systems. Arsenate ion was removed to a higher extent than chromate ion using the three-component composites, while the removal of chromate ion was found to be higher than arsenate ion when using the two-component composites (i.e., the control system). The project also aimed to elucidate the removal mechanisms of these synthesized composite materials by using appropriate adsorption and kinetic models. The adsorption of metal ions exhibited a range of adsorption behaviours as both the models (Langmuir and Freundlich) were found to fit most of the data recorded in different adsorption systems studied. The pseudo-second-order model was found to be the best fitted to describe the kinetics of heavy metal ion adsorption in all the composite adsorbent systems studied, in single-metal ion type and two-metal ion type solution systems. The ion-exchange mechanism was considered as one of the dominant mechanisms for the removal of cations (in single-metal and two-metal ion type solution systems) and arsenate ions (in industrial input stream solution systems) along with other adsorption mechanisms. In contrast, electrostatic attractions were considered to be the dominant mechanism of removal for chromate ions

    A comprehensive review on laser powder bed fusion of steels : processing, microstructure, defects and control methods, mechanical properties, current challenges and future trends

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    Laser Powder Bed Fusion process is regarded as the most versatile metal additive manufacturing process, which has been proven to manufacture near net shape up to 99.9% relative density, with geometrically complex and high-performance metallic parts at reduced time. Steels and iron-based alloys are the most predominant engi-neering materials used for structural and sub-structural applications. Availability of steels in more than 3500 grades with their wide range of properties including high strength, corrosion resistance, good ductility, low cost, recyclability etc., have put them in forefront of other metallic materials. However, LPBF process of steels and iron-based alloys have not been completely established in industrial applications due to: (i) limited insight available in regards to the processing conditions, (ii) lack of specific materials standards, and (iii) inadequate knowledge to correlate the process parameters and other technical obstacles such as dimensional accuracy from a design model to actual component, part variability, limited feedstock materials, manual post-processing and etc. Continued efforts have been made to address these issues. This review aims to provide an overview of steels and iron-based alloys used in LPBF process by summarizing their key process parameters, describing thermophysical phenomena that is strongly linked to the phase transformation and microstructure evolution during solidifica-tion, highlighting metallurgical defects and their potential control methods, along with the impact of various post-process treatments; all of this have a direct impact on the mechanical performance. Finally, a summary of LPBF processed steels and iron-based alloys with functional properties and their application perspectives are presented. This review can provide a foundation of knowledge on LPBF process of steels by identifying missing information from the existing literature

    Radionuclide and heavy metal sorption on to functionalised magnetic nanoparticles for environmental remediation

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    The presence of radionuclides and heavy metal ions in aqueous waste streams from industrial processes, especially in the nuclear waste industry, are a major concern. Many other processes are inherent producers of hazardous aqueous waste streams that require treatment for further disposal. These wastes quite often contain many contaminants, from harmful to very toxic. Contact with the environment, through groundwater or rivers, with such contaminants needs to be avoided. The ability to selectively sequester and remove contaminants from aqueous wastes with high loading capacities is of paramount importance to achieve full removal of the contaminants produced in many industries. The recent development of phosphate functionalised superparamagnetic magnetite ((PO)x-Fe3O4) nanoparticles have been shown to have ultra-high loading capacities and a high degree of selectivity towards uranium (U(VI)). The ability to manipulate these NPs with an external magnetic field gives these nanomaterials an advantage over many other conventional technologies in the field. These low-cost, non-toxic, and easily prepared magnetic NPs are highly biocompatible and have already been widely applied in the biotechnology and biomedical industries. The addition of specific functionalities allows for the fine tuning of the selectivity towards certain elements, therefore allowing full control over the selective removal of a wide range of contaminants. This study addresses the optimisation of the NPs manufacturing process that allows for the use of these NPs in a wider range of environments. Many of these waste streams are extreme environments, where they can be highly acidic or highly basic conditions. Therefore the feasibility of coating the Fe3O4 with silica (SiO2) was addressed, to provide an acid resistant layer and substrate for further functionalisation. Both the silica coating, and the applied surface functionality, were found to be stable against dissolution or chemical changes under acidic conditions from pH 1-4. Once acid resistance was established, the ability to extract a wide range of contaminant ions was also investigated. Sorption experiments with a wide range of contaminant ions were conducted to determine the selectivity and loading capacities of both (PO)x-Fe3O4 and (PO)x-SiO2@Fe3O4 NPs, at acidic (pH 3), neutral (pH 7), and basic (pH 11) conditions. Providing a basis for the manufacture of a state-of-the-art, novel extraction tool for both heavy metals and radionuclides. Inductively Coupled Plasma - Optical Emission Spectrometry (ICP-OES), Transmission Electron Microscopy (TEM), and Scanning Transmission Electron Microscopy - Energy Dispersive X-Ray (STEM-EDX) were used to achieve full characterisation of the NP complexes and supernatants to determine the successful extraction and presence of the contaminant metal ions used in this study. Determining the uptake kinetics, loading capacities for Cs(I), K(I), Na(I), Ca(II), Cd(II), Co(II), Cu(II), Mg(II), Mn(II), Mo(II), Ni(II), Pb(II), Sr(II), Al(III), Ce(III), Cr(III), Eu(III), Fe(III) and La(III) on to (PO)x-Fe3O4 and (PO)x-SiO2@Fe3O4 NPs. Implications of the use of these NPs in the extraction of radionuclides and heavy metals have been discussed in each case along with the potential for developing a broad-spectrum adsorbent. In conclusion, this PhD has shown the potential of these novel as-synthesised phosphate functionalised NP complexes to be utilised for heavy metal and radionuclide extraction, of a range of contaminants, from aqueous solutions, in acidic, neutral, and basic conditions. The production of these cost-effective and selective nanomaterials which exhibit rapid kinetics has the potential to be an important asset to the water treatment industry. Overall, these NP-complexes have been effective in fully removing a wide range of heavy metal contaminants and, therefore, have shown great promise to become a broad-spectrum adsorbent tool, which ultimately will aid in the clean-up of many new and legacy waste environments.Open Acces

    The Angel of Art Sees the Future Even as She Flies Backwards: Enabling Deep Relational Encounter Through Participatory Practice-Based Research.

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    This research addresses the current lack of opportunity within interdisciplinary arts practices for deep one-to-one relational encounters between creative practitioners operating in applied arts, performance, and workshop contexts with participant-subjects. This artistic problem is situated within the wider culture of pervasive social media, which continues to shape our interactions into forms that are characteristically faster, shorter, and more fragmented than ever before. Such dispersal of our attention is also accelerating our inability to deeply focus or relate for any real length of time. These modes of engaging within our technologically permeated, cosmopolitan and global society is escalating relational problems. Coupled with a constant bombardment of unrealistic visual images, mental health difficulties are also consequently rising, cultivating further issues such as identity ‘splitting’, (Lopez-Fernandez, 2019). In the context of the arts, this thesis proposes that such relational lack cannot be solved by one singular art form, one media modality, one existing engagement approach, or within a short participatory timeframe. Key to the originality of my thesis is the deliberate embodiment of a maternal experience. Feminist Lise Haller-Ross’ proposes that there is a ‘mother shaped hole in the art world’ and that, ‘as with the essence of the doughnut – we don’t need another hole for the doughnut, we need a whole new recipe’ (conference address, 2015). Indeed, her assertion encapsulates a need for different types of artistic and relational ingredients to be found. I propose these can be discovered within particular forms of maternal love; nurture; caring, and through conceptual relational states of courtship; intercourse; gestation, and birth. Furthermore, my maternal emphasis builds on: feminist, artist, and psychotherapist Bracha Ettinger’s (2006; 2015) notions of maternal, cohabitation and carrying; architect and phenomenologist Juhani Pallasmaa’s (2012) views on sensing and feeling; child psychoanalyst Donald Winnicott’s (1971) thoughts on transitional phenomena and perceptions of holding. Such psychotherapeutic and phenomenological theories are imbricated in-action within my multimodal arts processes. Additionally, by deliberately not privileging the ocular, I engage all my project participants senses and distil their multimodal data through an extended form of somatic and artistic Interpretive Phenomenological Analysis (IPA), (Smith, Flowers, and Larkin, 2009). IPA usefully focuses on the importance of the thematic and idiographic in terms of new knowledge generation, with an analytical focus on lived experience. Indeed, whilst the specifics of the participants in my minor and major projects are unique, my research activates and makes valid, findings that are collectively beneficial to the disciplines of applied and interdisciplinary arts; the field of practice-based research, and beyond. My original contribution to new knowledge as argued by this thesis, comprises both this text exposition and my practice. This sees the final generation of a new multimodal arts Participatory Practice-Based Framework (PartPb). Through this framework, the researcher-practitioner is seen to adopt a maternal role to gently guide project participants through four phases of co-created multimodal artwork generation. The four participatory ‘Phases’ are: Phase 1: Courtship – Digital Dialogues; Phase 2: Intercourse – Performative Encounters; Phase 3: Gestation – Screen Narratives; Phase 4: Birth – Relational Artworks. The framework also contains six researcher-only ‘Stages’: Stage 1: Participant Selection; Stage 2: Checking Distilled Themes; Stage 3: Location and Object Planning; Stage 4: Noticing, Logging, Sourcing; Stage 5: Collaboration and Construction; Stage 6: Releasing, Gifting, Recruiting. This new PartPb framework, is realised within a series of five practice-based (Pb) artworks called, ‘Minor Projects 1-5’, (2015-16) and Final Major Project, ‘Transformational Encounters: Touch, Traction, Transform’ (TETTT), (2018). These projects are likewise shaped through action-research processes of iterative testing, as developed from Candy and Edmonds (2010) Practice-based Research (PbR) trajectory. In my new PartPb framework, Candy, and Edmonds’ PbR processes are originally combined with a form of Fritz and Laura Perl’s Gestalt Experience Cycle (1947). This innovative fusion I come to term as a form of ‘Feeling Architecture,’ which is procedurally proven to hold and carry both researcher and participants alike, safely, ethically, and creatively through all Phases and Stages of artefact generation. Specifically, my new multimodal PartPb framework offers new knowledge to the field of Practice-Based Research (PbR) and practitioners working in multimodal arts and applied performance contexts. Due to its participatory focus, I develop on the term Practice-Based Research, (Candy and Edmonds, 2010) to coin the term Participatory Practice-Based Research, (PartPbR). The unique combination of multimodal arts and social-psychological methodologies underpinning my framework also has the potential to contribute to broader Arts, Well-Being, and Creative Health agendas, such as the UK government’s Social Prescribing and Arts and Health initiatives. My original framework offers future researchers’ opportunities to further develop, enhance and enrich individual and community well-being through its application to their own projects, and, in doing so, also starts to challenge unhelpful art binaries that still position community arts practices as somehow lesser to higher art disciplines

    Multifunctional Lightweight Structures of Silicon Carbide Nanowires

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    Silicon carbide (SiC) as a type of ceramic material possesses unique properties such as high hardness, good high temperature strength, and excellent oxidation resistance. However, the intrinsic shortcomings of ceramic-based materials, such as high brittleness, low recoverable compressibility, and low fatigue resistance, prevent their utilisations as structural or functional components. To overcome these issues, highly porous lightweight and flexible SiC ceramics constructed by nanowires are promising alternatives for advanced engineering applications. The aim of this thesis is therefore to fabricate highly porous lightweight and flexible SiC nanowire structures by three novel approaches: (1) in-situ chemical-blowing; (2) melamine foam-based replica template; (3) electrospinning and explore their properties towards different applications. The overview, including the aims and objectives of this thesis is outlined in Chapter 1. The existing knowledge about lightweight SiCNW structures including crystallography, synthesis approaches, physical properties (mechanical strength, thermal conductivity, high temperature stability), and well-developed energy and environment-related applications (piezoresistive sensors, catalyst support, absorbers, and filters) is documented in Chapter 2. The generic information of the starting materials, synthesis techniques, equipment, and method used for the fabrication of 3D SiCNW structures, characterisation of their microstructural features, and evaluation of the various aspects of their multifunctionalities is descripted in Chapter 3. To identify suitable techniques to assemble SiC nanowires (SiCNWs) into 3D architectures, Chapter 4 provides a selection of advanced manufacturing approaches for lightweight SiCNW structures with easy and precise control of the overall shape and growth of SiCNWs. Followed with the demonstration of the exciting properties of the as-obtained three SiCNW structures including mechanical properties, thermal insulation performance, thermo-oxidation resistance, and fire-retardance in Chapter 5. Finally, based on their own characteristics, the applications of the SiCNW structures such as piezoresistive sensors, catalyst support, and efficient absorbents for oil and organic solvents are present in Chapter 6. A guidance in the manufacturing of advanced ceramic nanowire structures with desired microstructures and properties tailored for specific applications will be eventually provided. I first demonstrated the creation of SiCNW sponges by a facile template/catalyst-free sugar-blowing technique, by reacting SiO2 with sustainable kitchen sugar, using NH4Cl as a blowing agent. The as-grown, highly porous SiCNW sponges exhibited a core-shell structure, the core part with a density of 115-125 mg cm-3 was comprised of short and tangled SiC whiskers with SiC flakes embedded, while the shell layer with an ultralow density of ~25 mg cm-3 consisted of numerous smooth SiCNWs. These sponges exhibited a compressive modulus of ~389 kPa, recoverability under cyclic compression loading for 100 cycles at a strain of 20% and a thermal conductivity of 42-92 mW m-1K-1. Secondly, I reported the fabrication of SiCNW scaffolds with tuneable microstructures, densities, and therefore properties, by regulating the solid loading content in the reticulated melamine foam (MF) template. The resulting samples exhibited high strength (modulus up to ~167.3 kPa), good recoverability (11% residual strain and 72% maximum stress after 100 compressive cycles at a Δ = 20%), and low thermal conductivity of 32-54 mW m-1K-1. Finally, I successfully created 3D SiCNW aerogels by using a Mille crĂȘpe stacking and sintering of the electrospun PAN/SiO2 fibres for the first time. The resulting aerogels made of interconnected SiCNWs displayed an ultralight density of 29 mg cm-3, excellent compressive recoverability and fatigue resistance. Meanwhile, the SiCNW aerogels exhibited a thermal conductivity of 24 mW m-1K-1, even lower than that of the air, suggesting its superinsulation capability. Benefitting from intrinsic properties of SiC, experimental results have shown that all the as-obtained SiCNW structures exhibited good thermal insulation performance, exceptional high-temperature stability, fire-retardance, and temperature-invariant elasticity. Furthermore, I have explored the best-suited functional applications for each SiCNW structure. The SiCNW sponges and aerogels with better compressive recoverability and mechanical stability exhibited interesting electromechanical sensing capability. The sponge-based sensor exhibited a gauge factor up to 87 and stable wide-range compression-resistance responses. Whilst the aerogel-based strain sensor with higher recoverable strains presented stable sensing behaviour at different strains, frequencies, elevated temperatures over 200 °C and excellent repeatability over 2000 cycles. Owing to the cellular structure with the co-existence of SiC nanowires and struts, good interconnectivity, and competent mechanical strength and stability, the SiCNW scaffolds demonstrated the exclusive suitability as excellent support for MOF-derived TiO2-C catalyst, with ~35% enhanced in-situ loading of the catalyst, enabling a superior photocatalytic performance and good repeatability for at least 3 cycles. I further examined the SiCNW structures as organic solvent/oil absorbent. They exhibited rapid absorption of various organic solvents and oils. Typically, the SiCNW aerogels possess the highest absorption capacity of 32-86 g g-1, as well as robust recoverability. Meanwhile, the absorbed content can be easily removed by squeezing, distillation, and combustion, while the SiCNW structures remain unchanged. These features have shown that the SiCNW structures are promising for applications for the potential removal of chemical spills and oil leakage, with the advantage of easy recycling. All these remarkable findings will not only provide an important opportunity to advance the understanding of lightweight SiCNWs structures and make original contributions to utilise them as multifunctional devices, but also bring us the new ways to reshape the manufacturing of porous ceramics for future energy and environment-related applications

    Deposição de filmes do diamante para dispositivos electrónicos

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    This PhD thesis presents details about the usage of diamond in electronics. It presents a review of the properties of diamond and the mechanisms of its growth using hot filament chemical vapour deposition (HFCVD). Presented in the thesis are the experimental details and discussions that follow from it about the optimization of the deposition technique and the growth of diamond on various electronically relevant substrates. The discussions present an analysis of the parameters typically involved in the HFCVD, particularly the pre-treatment that the substrates receive- namely, the novel nucleation procedure (NNP), as well as growth temperatures and plasma chemistry and how they affect the characteristics of the thus-grown films. Extensive morphological and spectroscopic analysis has been made in order to characterise these films.Este trabalho discute a utilização de diamante em aplicaçÔes electrĂłnicas. É apresentada uma revisĂŁo detalhada das propriedades de diamante e dos respectivos mecanismos de crescimento utilizando deposição quĂ­mica a partir da fase vapor com filament quente (hot filament chemical vapour deposition - HFCVD). Os detalhes experimentais relativos Ă  otimização desta tĂ©cnica tendo em vista o crescimento de diamante em vĂĄrios substratos com relevĂąncia em eletrĂłnica sĂŁo apresentados e discutidos com detalhe. A discussĂŁo inclui a anĂĄlise dos parĂąmetros tipicamente envolvidos em HFCVD, em particular do prĂ©-tratamento que o substrato recebe e que Ă© conhecido na literatura como "novel nucleation procedure" (NNP), assim como das temperaturas de crescimento e da quĂ­mica do plasma, bem como a influĂȘncia de todos estes parĂąmetros nas caracterĂ­sticas finais dos filmes. A caracterização morfolĂłgica dos filmes envolveu tĂ©cnicas de microscopia e espetroscopia.Programa Doutoral em Engenharia EletrotĂ©cnic

    Évaluation de la durabilitĂ© des pieux en bĂ©ton armĂ© de barres et de spirales de PRFV en milieu marin

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    Abstract : Conventional concrete reinforced (RC) with black steel in marine environment suffers damage due to corrosion. Most field examination studies found heavy corrosion before achieving 75-100 years of the service life desired by the Federal Highway Administration (FHWA). Lately, glass fiber-reinforced polymers (GFRP) as internal reinforcement in concrete have proved outstanding structural and long-term durability performance in corrosive environments. The last three decades witnessed a significant revolution in the usage of GFRP in civil engineering projects to raise the service lives and reduce maintenance costs of RC structures. Over three-thousands bridges over Canada and U.S. included GFRP bars as reinforcement for constructing the most elements vulnerable to corrosion due to de-icing salts and annual thermal changes (i.e., deck slabs) as well as the usage in reinforcing the culvert bridges in the U.S. The field examination for the bridge’s barrier walls, deck slabs, and culvert built with GFRP bars after 10-20 years in service indicates good long-term durability. The usage of GFRP bars and spirals in the RC columns, piers, and piling system is widely accepted and recommended in most conclusions of previous studies. Most investigations in the past have focused mainly on the behavior of RC piles/columns under concentric, eccentric, and cyclic loading, disregarding the relationship between the structural and durability behavior. This thesis presents the results of the axial compression test for forty-eight RC square and circular piles exposed to the marine environment and two conditioning temperatures for 12-months. All specimens have laboratory-scale dimensions measuring 300 mm for square pile's width, 304 mm for circular pile's diameter, and 1000 mm general height. The durability conditioning regime is comprised of two environments; (i) simulation for the marine environment in sub-tropical regions (22°C), (ii) simulated marine environment at accelerated temperature (60°C). Phase (I) contains 18-concrete square piles and Phase (II) includes 18-concrete circular piles. The thirty-six concrete piles were: six specimens were without internal reinforcement, 6-specimens were reinforced with hybrid reinforcement (steel bars and GFRP spirals), and the remaining twentyfour specimens were fabricated with pristine GFRP bars and spirals. For each phase, twelve pile specimens were subjected to the conditioning regime for 12-months, six specimens for each conditioning temperature. Whereas phase (III) includes 6- square and 6-circular RC piles, which were made of GFRP reinforcement directly immersed in the simulated marine environment at 22 and 60°C for 12-months before integrating into concrete, three GFRP-cages for each aging temperature. Several structural variables were investigated through the three phases such as longitudinal reinforcement (ratio and diameter) and transverse reinforcement (pitch and configurations). In addition, a microstructural analysis program (SEM, DSC, and FTIR) was carried out on GFRP material extracted from the aged piles and those directly exposed to the conditioning regime. Concrete cores taken from the aged piles were examined by optical microscopy (OM) to assess the bond between concrete and bars/spirals. This thesis also introduces a characterization for GFRP bars exposed directly to the marine environment based on tensile, bond, and horizontal shear tests. The experimental axial compression capacities of GFRP-RC piles were compared with the values predicted using the available design equations in the current design codes. The results obtained from microstructural analyses showed that GFRP reinforcement used in this study possesses good long-term durability in concrete saturated with the marine environment or in solutions simulated seawater environments at 60°C after 12-months. OM images for the concrete/bar contact circumference revealed that bars/spirals firmly bond to concrete. A 0.85 is the lowest retention in the tensile and bond strengths of GFRP bars, while the retention in horizontal shear strength reaches 0.95 after direct exposure to the marine environment at 60°C for 12-months. Based on the compressive tests, the axial compression behavior of GFRP-RC square and circular pile did not adversely affect by immersion in the simulated marine environment at 22 or 60°C for 12-months or using pre/conditioned GFRP material. The axial compression capacity of ten GFRP-RC pile specimens submerged in the simulated marine environment at 60°C was enhanced by 116-125% compared to their unconditioned counterparts as a result of an increase in the concrete compressive strength. Specimens fabricated with GFRP material aged at 60°C exhibited similar ductile behavior and axial compression capacities of their counterparts constructed with pristine GFRP material. Despite the tensile strength reduction after exposure to aggressive environments, GFRP reinforcing materials effectively perform their structural function as internal reinforcement of RC piles. All investigated structural variables effectively affect the compressive behavior of GFRP-RC piles in the marine environment. The reduction factors for GFRP-RC structures specified in CSA (2019a) and AASHTO (2018a), and CSA (2017) yielded lower axial compression capacities than those obtained experimentally. A more accurate design equation to calculate the axial load capacity of the GFRP RC piles should consider the contribution of longitudinal GFRP bars even when exposed to severe marine environments.Le bĂ©ton conventionnel armĂ© (RC) avec de l'acier noir dans un environnement marin subit des dommages dus Ă  la corrosion. La plupart des Ă©tudes d'examen sur le terrain ont rĂ©vĂ©lĂ© une forte corrosion avant d'atteindre les 75-100 ans de la durĂ©e de vie souhaitĂ©e par la Federal Highway Administration (FHWA). RĂ©cemment, les polymĂšres renforcĂ©s de fibres de verre (PRFV) utilisĂ©s comme armature interne dans le bĂ©ton ont prouvĂ© qu'ils prĂ©sentaient des performances structurelles et de durabilitĂ© Ă  long terme exceptionnelles dans des environnements corrosifs. Les trois derniĂšres dĂ©cennies ont vu une rĂ©volution significative dans l'utilisation des PRFV dans les projets de gĂ©nie civil pour augmenter la durĂ©e de vie et rĂ©duire les coĂ»ts de maintenance des structures en bĂ©ton armĂ©. Plus de trois mille ponts au Canada et aux États-Unis ont inclus des barres GFRP comme renforcement pour la construction des Ă©lĂ©ments les plus vulnĂ©rables Ă  la corrosion due aux sels de dĂ©glaçage et aux changements thermiques annuels (c'est-Ă -dire les dalles de pont), ainsi que pour le renforcement des ponceaux aux États-Unis. L'examen sur le terrain des murs de protection, des dalles de pont et des ponceaux construits avec des barres GFRP aprĂšs 10 Ă  20 ans de service indique une bonne durabilitĂ© Ă  long terme. L'utilisation de barres et de spirales en GFRP dans les colonnes, les piliers et les systĂšmes de pilotis en bĂ©ton armĂ© est largement acceptĂ©e et recommandĂ©e dans la plupart des conclusions des Ă©tudes prĂ©cĂ©dentes. La plupart des recherches dans le passĂ© se sont concentrĂ©es principalement sur le comportement des pieux/colonnes en bĂ©ton armĂ© sous des charges concentriques, excentriques et cycliques, sans tenir compte de la relation entre le comportement structurel et la durabilitĂ©. Cette thĂšse prĂ©sente les rĂ©sultats de l'essai de compression axiale pour quarante-huit pieux RC carrĂ©s et circulaires exposĂ©s Ă  l'environnement marin et Ă  deux tempĂ©ratures de conditionnement pendant 12 mois. Tous les spĂ©cimens ont des dimensions Ă  l'Ă©chelle du laboratoire mesurant 300 mm pour la largeur du pieu carrĂ©, 304 mm pour le diamĂštre du pieu circulaire, et 1000 mm de hauteur gĂ©nĂ©rale. Le rĂ©gime de conditionnement de durabilitĂ© est composĂ© de deux environnements ; (i) simulation pour l'environnement marin dans les rĂ©gions subtropicales (22°C), (ii) environnement marin simulĂ© Ă  tempĂ©rature accĂ©lĂ©rĂ©e (60°C). La phase (I) comprend 18 pieux carrĂ©s en bĂ©ton et la phase (II) comprend 18 pieux circulaires en bĂ©ton. Les trente-six pieux en bĂ©ton Ă©taient les suivants : six spĂ©cimens n'avaient pas d'armature interne, six spĂ©cimens Ă©taient renforcĂ©s par une armature hybride (barres d'acier et spirales GFRP), et les vingt-quatre spĂ©cimens restants Ă©taient fabriquĂ©s avec des barres et des spirales GFRP vierges. Pour chaque phase, douze spĂ©cimens de pieux ont Ă©tĂ© soumis au rĂ©gime de conditionnement pendant 12 mois, six spĂ©cimens pour chaque tempĂ©rature de conditionnement. Tandis que la phase (III) comprend 6 pieux RC carrĂ©s et 6 circulaires, qui ont Ă©tĂ© rĂ©alisĂ©s avec des armatures GFRP directement immergĂ©es dans l'environnement marin simulĂ© Ă  22 et 60°C pendant 12 mois avant d'ĂȘtre intĂ©grĂ©es dans le bĂ©ton, trois cages GFRP pour chaque tempĂ©rature de vieillissement. Plusieurs variables structurelles ont Ă©tĂ© Ă©tudiĂ©es au cours des trois phases, telles que les armatures longitudinales (ratio et diamĂštre) et les armatures transversales (pas et configurations). De plus, un programme d'analyse microstructurelle (SEM, DSC, et FTIR) a Ă©tĂ© rĂ©alisĂ© sur le matĂ©riau GFRP extrait des pieux vieillis et ceux directement exposĂ©s au rĂ©gime de conditionnement. Des carottes de bĂ©ton prĂ©levĂ©es sur les pieux vieillis ont Ă©tĂ© examinĂ©es par microscopie optique (OM) pour Ă©valuer la liaison entre le bĂ©ton et les barres/spirales. Cette thĂšse prĂ©sente Ă©galement une caractĂ©risation des barres GFRP exposĂ©es directement Ă  l'environnement marin, basĂ©e sur des essais de traction, de liaison et de cisaillement horizontal. Les capacitĂ©s expĂ©rimentales de compression axiale des pieux en GFRP-RC ont Ă©tĂ© comparĂ©es aux valeurs prĂ©dites en utilisant les Ă©quations de conception disponibles dans les codes de conception actuels. Les rĂ©sultats obtenus Ă  partir des analyses microstructurales ont montrĂ© que le renforcement GFRP utilisĂ© dans cette Ă©tude possĂšde une bonne durabilitĂ© Ă  long terme dans du bĂ©ton saturĂ© de l'environnement marin ou dans des solutions simulant des environnements d'eau de mer Ă  60°C aprĂšs 12 mois. Les images OM de la circonfĂ©rence de contact bĂ©ton/barre ont rĂ©vĂ©lĂ© que les barres/spirales adhĂšrent fermement au bĂ©ton. Une rĂ©tention de 0,85 est la plus faible dans les rĂ©sistances Ă  la traction et Ă  l'adhĂ©rence des barres GFRP, tandis que la rĂ©tention de la rĂ©sistance au cisaillement horizontal atteint 0,95 aprĂšs une exposition directe Ă  l'environnement marin Ă  60°C pendant 12 mois. D'aprĂšs les essais de compression, le comportement en compression axiale des pieux carrĂ©s et circulaires en GFRP-RC n'a pas Ă©tĂ© affectĂ© par l'immersion dans l'environnement marin simulĂ© Ă  22 ou 60°C pendant 12 mois ou par l'utilisation de matĂ©riau GFRP prĂ©-conditionnĂ©. La capacitĂ© de compression axiale de dix spĂ©cimens de pieux RC en GFRP immergĂ©s dans un environnement marin simulĂ© Ă  60°C a Ă©tĂ© augmentĂ©e de 116-125% par rapport Ă  leurs homologues non conditionnĂ©s en raison d'une augmentation de la rĂ©sistance Ă  la compression du bĂ©ton. Les spĂ©cimens fabriquĂ©s avec un matĂ©riau GFRP vieilli Ă  60°C ont prĂ©sentĂ© un comportement ductile et des capacitĂ©s de compression axiale similaires Ă  ceux de leurs homologues construits avec un matĂ©riau GFRP vierge. MalgrĂ© la rĂ©duction de la rĂ©sistance Ă  la traction aprĂšs exposition Ă  des environnements agressifs, les matĂ©riaux de renforcement GFRP remplissent efficacement leur fonction structurelle en tant que renforcement interne des pieux RC. Toutes les variables structurelles Ă©tudiĂ©es affectent efficacement le comportement en compression des pieux GFRP-RC dans l'environnement marin. Les facteurs de rĂ©duction pour les structures en GFRP-RC spĂ©cifiĂ©s dans CSA (2019a) et AASHTO (2018a), et CSA (2017) ont donnĂ© des capacitĂ©s de compression axiale infĂ©rieures Ă  celles obtenues expĂ©rimentalement. Une Ă©quation de conception plus prĂ©cise pour calculer la capacitĂ© de charge axiale des pieux RC en GFRP devrait tenir compte de la contribution des barres longitudinales en GFRP, mĂȘme lorsqu'elles sont exposĂ©es Ă  des environnements marins sĂ©vĂšres
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