1,010 research outputs found

    Hybrid polymer inclusion membrane as anion exchange membrane for recovering Pd2+ ions in electrogenerative process

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    A novel non-plasticized nano-porous hybrid inorganic-organic polymer inclusion membrane (PIM) was synthesized, characterized, and evaluated as an anion exchange membrane for application in electrogenerative processes to recover Pd2+ ions. Ionic liquids 1-ethyl-3-me­thyl­imidazolium chloride (EMIM-Cl) and 1-butyl-3-methylimidazolium chloride (BMIM-Cl) were used as the carrier molecules in the polymeric network of PIM to enhance anion exchange process. This hybrid anion exchange membrane also consists of a polymeric matrix of non-plasticized cellulose triacetate modified by incorporating an inorganic material (silane) prepared by the sol-gel route. Different parameters affecting the ion transport performance efficiency, i.e., the composition of the membrane, type of ionic liquid (carrier molecule) and ion–exchange capacity, were investigated and optimized. In the electrogenerative process, the results revealed that the prepared PIM yields better recovery results for recovering Pd2+ ions from its chloride solution compared to the commercial anion exchange membrane Neosepta® AM-01, with a full recovery of 100 mg/L Pd2+ ions in 30 min. This preliminary study shows that the prepared low-cost hybrid anion exchange membrane PIM can act as an inexpensive material suitable for the rapid and efficient recovery of Pd2+ ions from an aqueous solution

    A Methodology to Enable Concurrent Trade Space Exploration of Space Campaigns and Transportation Systems

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    Space exploration campaigns detail the ways and means to achieve goals for our human spaceflight programs. Significant strategic, financial, and programmatic investments over long timescales are required to execute them, and therefore must be justified to decision makers. To make an informed down-selection, many alternative campaign designs are presented at the conceptual-level, as a set and sequence of individual missions to perform that meets the goals and constraints of the campaign, either technical or programmatic. Each mission is executed by in-space transportation systems, which deliver either crew or cargo payloads to various destinations. Design of each of these transportation systems is highly dependent on campaign goals and even small changes in subsystem design parameters can prompt significant changes in the overall campaign strategy. However, the current state of the art describes campaign and vehicle design processes that are generally performed independently, which limits the ability to assess these sensitive impacts. The objective of this research is to establish a methodology for space exploration campaign design that represents transportation systems as a collection of subsystems and integrates its design process to enable concurrent trade space exploration. More specifically, the goal is to identify existing campaign and vehicle design processes to use as a foundation for improvement and eventual integration. In the past two decades, researchers have adopted terrestrial logistics and supply chain optimization processes to the space campaign design problem by accounting for the challenges that accompany space travel. Fundamentally, a space campaign is formulated as a network design problem where destinations, such as orbits or surfaces of planetary bodies, are represented as nodes with the routes between them as arcs. The objective of this design problem is to optimize the flow of commodities within network using available transport systems. Given the dynamic nature and the number of commodities involved, each campaign can be modeled as a time-expanded, generalized multi-commodity network flow and solved using a mixed integer programming algorithm. To address the challenge of modeling complex concept of operations (ConOps), this formulation was extended to include paths as a set of arcs, further enabling the inclusion of vehicle stacks and payload transfers in the campaign optimization process. Further, with the focus of transportation system within this research, the typical fixed orbital nodes in the logistics network are modified to represent ranges of orbits, categorized by their characteristic energy. This enables the vehicle design process to vary each orbit in the mission as it desires to find the best one per vehicle. By extension, once integrated, arc costs of dV and dT are updated each iteration. Once campaign goals and external constraints are included, the formulated campaign design process generates alternatives at the conceptual level, where each one identifies the optimal set and sequence of missions to perform. Representing transportation systems as a collection of subsystems introduces challenges in the design of each vehicle, with a high degree of coupling between each subsystem as well as the driving mission. Additionally, sizing of each subsystem can have many inputs and outputs linked across the system, resulting in a complex, multi-disciplinary analysis, and optimization problem. By leveraging the ontology within the Dynamic Rocket Equation Tool, DYREQT, this problem can be solved rapidly by defining each system as a hierarchy of elements and subelements, the latter corresponding to external subsystem-level sizing models. DYREQT also enables the construction of individual missions as a series of events, which can be directly driven and generated by the mission set found by the campaign optimization process. This process produces sized vehicles iteratively by using the mission input, subsystem level sizing models, and the ideal rocket equation. By conducting a literature review of campaign and vehicle design processes, the different pieces of the overall methodology are identified, but not the structure. The specific iterative solver, the corresponding convergence criteria, and initialization scheme are the primary areas for experimentation of this thesis. Using NASA’s reference 3-element Human Landing System campaign, the results of these experiments show that the methodology performs best with the vehicle sizing and synthesis process initializing and a path guess that minimizes dV. Further, a converged solution is found faster using non-linear Gauss Seidel fixed point iteration over Jacobi and set of convergence criteria that covers vehicle masses and mission data. To show improvement over the state of the art, and how it enables concurrent trade studies, this methodology is used at scale in a demonstration using NASA’s Design Reference Architecture 5.0. The LH2 Nuclear Thermal Propulsion (NTP) option is traded with NH3and H2O at the vehicle-level as a way to show the impacts of alternative propellants on the vehicle sizing and campaign strategy. Martian surface stay duration is traded at the campaign-level through two options: long-stay and short-stay. The methodology was able to produce four alternative campaigns over the course of two weeks, which provided data about the launch and aggregation strategy, mission profiles, high-level figures of merit, and subsystem-level vehicle sizes for each alternative. Expectedly, with their lower specific impulses, alternative NTP propellants showed significant growth in the overall mass required to execute each campaign, subsequently represented the number of drop tanks and launches. Further, the short-stay campaign option showed a similar overall mass required compared to its long-stay counterpart, but higher overall costs even given the fewer elements required. Both trade studies supported the overall hypothesis and that integrating the campaign and vehicle design processes addresses the coupling between then and directly shows the impacts of their sensitivities on each other. As a result, the research objective was fulfilled by producing a methodology that was able to address the key gaps identified in the current state of the art.Ph.D

    Development of DNA origami-based tools for cancer treatment

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    DNA has been used as material for the assembly of objects at different scales. Particularly, the introduction of DNA origami has been inspiring the design and construction of many different versions of DNA nanostructures for, especially, biomedical applications. DNA origami nanostructures are showing unique advantages, including structural homogeneity, addressability, biocompatibility, and capacity to carry pharmaceuticals or biomolecules, for the development of future cancer therapeutics. To fully unlock their potential, however, they need to be tailored based on physiological and pathological molecular environments which they interact with. In this thesis, we develop a few functionalized DNA origami nanostructures to investigate specific questions of cancer biology or to overcome challenges of cancer immunotherapy. In PAPER I, we compare the physical characteristics of a compact lattice-based rod and a wireframe-styled rod and revealed how they interact with cell spheroid tissue models (CSTMs). Our data indicate that the wireframe structure, which has a lower local material density in design, has higher local deformability than the lattice-based structure. We reveal that these physical differences play important roles in the interaction between DNA origami nanostructures and human cancer cells, showing that wireframe rods are more likely to stay on the cell membrane, rather than being internalized, and this facilitates their deeper penetration into CSTMs. These observations tell us that DNA origami design methods should be carefully considered in DNA origami-based drug delivery applications. In PAPER II, to explore the nanoscale clustering effect of death receptor 5 (DR5) on human breast cancer cells, we develop flat sheet-like DNA origami nanostructures and functionalize them with the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)- mimicking peptides which can recognize and bind with DR5, in differently sized hexagonal patterns. Experiments of cancer cells and DNA origami incubation show that apoptosis can be precisely controlled when we vary the size of peptide patterns between the range of 6 nm to 26 nm. Interestingly, our data indicate that the interpeptide distance for effective apoptosis is sub-10 nm. Our findings highlight the potency of precise spatial patterning of ligands on apoptosis signaling. In PAPER III, to limit cytotoxicity of the sub-10 nm peptide pattern, which we have screened out in the work of PAPER II, only to tumors, we design a three-dimensional DNA origami nanostructure containing a 6 nm wide and 12 nm deep cavity and use it to hide but display the peptide pattern according to the acidity of the tissue microenvironment. Peptide display is achieved by the protonation-triggered formation of the DNA triplex, during which a singlestranded DNA extension from the complementary strand of a mini-scaffold DNA wraps back to the mini-scaffold duplex. By varying the AT percentage in the mini-scaffold DNA, we can control the triggering pH for the formation of the DNA triplex. We demonstrate the safety of the DNA origami under physiological pH (pH 7.4) for non-cancer cells and its cytotoxicity to cancer cells under the pH of solid tumors (pH 6.5). In PAPER IV, to mimic functions of T cell engagers but mitigate corresponding adverse effects mainly caused by “on-target, off-tumor” immune activation and cytokine release syndrome, we develop a wireframe DNA origami based-nanorobot: a double-layered barrellike origami with antibodies inside under its closed status. When the DNA nanorobot presents as its open configuration, internal antibodies get exposed, functioning to engage T cells with cancer cells and activate T cell immune killing. By spatiotemporally controlling the opening of the DNA nanorobot via signals from cancer cells, tumor microenvironment, or external stimulus, we aim to selectively redirect the cytotoxicity of T cells to solid cancers and substantially mitigate corresponding adverse effects of current T cell engagers-based cancer immunotherapy

    Breaking Implicit Assumptions of Physical Delay-Feedback Reservoir Computing

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    The Reservoir Computing (RC) paradigm is a supervised machine learning scheme using the natural computational ability of dynamical systems. Such dynamical systems incorporate time delays showcasing intricate dynamics. This richness in dynamics, particularly the system's transient response to external stimuli makes them suitable for RC. A subset of RCs, Delay-Feedback Reservoir Computing (DFRC), is distinguished by its unique features: a system that consists of a single nonlinear node and a delay-line, with `virtual' nodes defined along the delay-line by time-multiplexing procedure of the input. These characteristics render DFRC particularly useful for hardware integration. In this thesis, the aim is to break the implicit assumptions made in the design of physical DFRC based on Mackey-Glass dynamical system. The first assumption we address is the performance of DFRC is not affected by the attenuation in physcial delay-line as the nodes defined along it are 'virtual'. However, our experimental results contradict this. To mitigate the impact of losses along the delay line, we propose a methodology `Devirtualisation', which describes the procedure of directly tapping into the delay lines at the position of a `virtual' node, rather than at the delay line's end. It trade-offs the DFRC system's read-out frequency and the quantity of output lines. Masking plays a crucial role in DFRC, as it defines `virtual' nodes along the delay-line. The second assumption is that the mask used should randomly generated numbers uniformly distributed between [-u,u]. We experimentally compare Binary Weight Mask (BWM) vs. Random Weight Mask (RWM) under different scenarios; and investigate the randomness of BWM signal distribution's impact. The third implicit assumption is that, DFRC is designed to solve time series prediction tasks involving a single input and output with no external feedback. To break this assumption, we propose two approaches to mix multi-input signals into DFRC; to validate these approaches, a novel task for DFRC that inherently necessitates multiple inputs: the control of a forced Van der Pol oscillator system, is proposed

    Investigating the role of circulating cell-free dna as a mechanistic biomarker in inflammatory bowel disease: development of an integrated precision-medicine enabled platform in Scotland

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    BACKGROUND: Circulating cell-free DNA (cfDNA) represents a class of biological molecules whose role in inflammation remains poorly understood. Inflammatory bowel disease (IBD), from ulcerative colitis to Crohn’s disease, comprises a spectrum of chronic immune-mediated conditions with complex pathogenic mechanisms that manifest primarily as gut-mucosal inflammation. There remains an unmet need that requires a greater understanding of disease mechanisms to find better treatments for patients. HYPOTHESIS/METHODS: cfDNA is a biomarker in IBD that captures a dimension of disease activity not covered by current clinical biomarkers. Mitochondrial cfDNA may identify a subset of patients whose disease is driven by immune-mediated recognition of mitochondrial cfDNA. cfDNA metagenomics may provide new insights into disease biology. Two multi-centre translational cohort studies were set up – GI-DAMPs (cross-sectional) and MUSIC (longitudinal) and the execution of which is discussed. Clinical sampling was performed, and subsequent analysis was carried out using Qubit for total quantification, digital polymerase chain reaction (dPCR) for COX3, ND2 and GAPDH genes, fragment analysis with the Agilent BioAnalyzer, and cfDNA sequencing using both Nanopore and Illumina platforms. RESULTS: Patients with highly active IBD (requiring admission to hospital) had significantly higher total cfDNA (median 0.52 ng/uL, Kruskal-Wallis p<0.001), mitochondrial ND2 (median 359 copies/uL, Kruskal-Wallis p<0.05) and genomic GAPDH levels (median 8.7 copies/uL, Kruskal-Wallis p<0.01) compared to patients with active disease or remission. Digital PCR techniques provide better resolution compared to Qubit. cfDNA fragment analysis shows an increase in the 160bp peak and the release of longer fragments in highly active disease, suggesting increased apoptosis and necrosis, compared to patients in remission or healthy controls. cfDNA sequencing and bioinformatic analysis were feasible. cfDNA metagenomics reveals that patients with active disease have reduced alpha diversity (median Chao1 2612, p=0.07 and median Shannon 0.06, p=0.43) and significantly different beta diversity profiles (permanova R2 0.766, p<0.01) compared to patients in remission or healthy controls. CONCLUSION: The analysis of cfDNA with modern advances in technology is an unexplored dimension of inflammation biology. cfDNA correlates with IBD activity and further study is required to validate its use as a clinical and mechanistic biomarker. Further scientific work in cfDNA could unlock new insights into both cfDNA and IBD biology, potentially allowing the development of better mechanistic and predictive biomarkers, new therapeutics, and general insights into other inflammatory diseases

    Cycling of block copolymer composites with lithium-conducting ceramic nanoparticles

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    Solid polymer and perovskite-type ceramic electrolytes have both shown promise in advancing solid-state lithium metal batteries. Despite their favorable interfacial stability against lithium metal, polymer electrolytes face issues due to their low ionic conductivity and poor mechanical strength. Highly conductive and mechanically robust ceramics, on the other hand, cannot physically remain in contact with redox-active particles that expand and contract during charge-discharge cycles unless excessive pressures are used. To overcome the disadvantages of each material, polymer-ceramic composites can be formed; however, depletion interactions will always lead to aggregation of the ceramic particles if a homopolymer above its melting temperature is used. In this study, we incorporate Li0.33La0.56TiO3 (LLTO) nanoparticles into a block copolymer, polystyrene-b-poly (ethylene oxide) (SEO), to develop a polymer-composite electrolyte (SEO-LLTO). TEMs of the same nanoparticles in polyethylene oxide (PEO) show highly aggregated particles whereas a significant fraction of the nanoparticles are dispersed within the PEO-rich lamellae of the SEO-LLTO electrolyte. We use synchrotron hard x-ray microtomography to study the cell failure and interfacial stability of SEO-LLTO in cycled lithium-lithium symmetric cells. Three-dimensional tomograms reveal the formation of large globular lithium structures in the vicinity of the LLTO aggregates. Encasing the SEO-LLTO between layers of SEO to form a “sandwich” electrolyte, we prevent direct contact of LLTO with lithium metal, which allows for the passage of seven-fold higher current densities without signatures of lithium deposition around LLTO. We posit that eliminating particle clustering and direct contact of LLTO and lithium metal through dry processing techniques is crucial to enabling composite electrolytes

    Modulating aluminum solvation with ionic liquids for improved aqueous-based aluminum-ion batteries

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    Aqueous-based Al-ion batteries are attractive alternatives to Li-ion batteries due to their safety, high volumetric energy density, abundance, and recyclability. Although aluminum-ion batteries are attractive, there are major challenges to overcome, which include understanding the nature of the passive layer of aluminum oxide on the aluminum anode, the narrow electrochemical window of aqueous electrolytes, and lack of suitable cathodes. Here, we report using experiments in conjunction with DFT simulations to clarify the role of ionic liquids (ILs) in altering the Al solvation dynamics, which in turn affects the aluminum electrochemistry and aqueous-based battery performance significantly. DFT calculations showed that the addition of 1-ethyl-3-methylimidazolium trifluoromethylsulfonate (EMIMTfO) changes the aluminum solvation structure in the aqueous (Al(TfO)3) electrolyte to lower coordinated solvation shells, thereby influencing and improving Al deposition/stripping on the Zn/Al alloy anode. Furthermore, the addition of an IL reduces the strain in manganese oxide during intercalation/deintercalation, thereby improving the Zn/Al-MnOx battery performance. By optimizing the electrolyte composition, a battery potential of >1.7 V was achieved for the Zn/Al-MnOx system

    Silver is not equal to silver : synthesis and evaluation of silver nanoparticles with low biological activity, and their incorporation into C12C_{12}alanine-based hydrogel

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    A new type of silver nanoparticles (AgNPs) was prepared and comprehensively studied. Scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses indicated that 24 nm AgNPs with narrow size distribution were obtained while Z-potential confirms their good stability. The composites of the obtained AgNPs with nontoxic-nature-inspired hydrogel were formed upon cooling of the aqueous solution AgNPs and C12Ala. The thermal gravimetric analysis (TGA) and the differential scanning calorimetry (DSC) do not show significant shifts in the characteristic temperature peaks for pure and silver-enriched gels, which indicates that AgNPs do not strongly interact with C12Ala fibers, which was also confirmed by SEM. Both AgNPs alone and in the assembly with the gelator C12Ala were almost biologically passive against bacteria, fungus, cancer, and nontumor human cells, as well as zebra-fish embryos. These studies proved that the new inactive AgNPs-doped hydrogels have potential for the application in therapy as drug delivery media

    System-in-package for IoT sigfox applications

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    In this work, the System-in-Package (SiP) electronic circuit manufacturing technology is presented as an economically viable alternative for implementing solutions where circuits processed in different technologies need to be integrated into a single, compact device. This technology is explored here through the development of a complete hardware plat form designed for implementing devices for the Internet of Things (IoT) in the SigFox standard. The platform consists of an RF front-end module, a sub-GHz radio transceiver capable of operating in any global SigFox configuration, and an ARM M0+ microcon troller with 64 Kbytes of Flash memory, 8 Kbytes of RAM, a 2Kbyte EEPROM, a 12-bit 1.14Msps analog-to-digital multi-channel interface, a 12-bit digital-to-analog interface, ultra-low-power comparators for implementing a wake-up system, and a complete set of digital communication peripherals. In addition to this SiP, only a power source (e.g. two AAA batteries) and an antenna are required to implement applications on the SigFox network. The system integrates an MCU, a radio transceiver, and an RF front-end module, enabling global operation of this device through Sigfox Monarch technology. The SiP operates from a supply voltage of 2.7-3.6 V, and its RF output power is programmable in the range of -30 dBm to 26 dBm. Operating at a supply voltage of 3.3V, it consumes 188.5 mA or 23 mA for RF output power of 22 dBm or 12.8 dBm, at 902.2MHz and 868.13 MHz, respectively. The device also offers a current consumption of 3 µ A in deep sleep mode. The proposed SiP design has successfully met all the requirements for Sigfox Verified certification, enabling the Sigfox Monarch function as well. Currently, it represents the solution with the smallest dimensions approved for Sigfox in the global market, measur ing only 13 mm × 13 mm × 1.1 mm.Neste trabalho é apresentada a tecnologia de fabricação de circuitos eletrônicos System in-Package (SiP), que se oferece como uma alternativa economicamente interessante para a implementação de soluções, onde circuitos processados em tecnologias diversas devem ser integrados em um único dispositivo de tamanho mínimo. Esta tecnologia é aqui explorada através do desenvolvimento de uma plataforma completa de hardware, voltada à implementação de dispositivos para a Internet das Coisas (IoT) no padrão SigFox. Esta plataforma é composta por um módulo front-end de RF, um rádio transceptor sub-GHz, capaz de operar em qualquer configuração global do padrão SigFox, além de um micro controlador ARM M0+, com 64 Kbytes de memória Flash, 8 Kbytes de memória RAM, uma EEPROM de 2Kbytes, interface multi-canal analógico-digital de 12 bits e 1.14Msps, interface digital-analógico de 12 bits, comparadores ultra-low-power para implementação de um sistema de wake-up e linha completa de periféricos de comunicação digital. Além deste SiP, é necessário apenas a conexão de uma fonte de energia (bateria ou 2 pilhas AAA) e de uma antena, para implementar aplicações ma rede SigFox. O sistema integra uma MCU, um rádio transceptor e um módulo front-end de RF, que habilita a operação global deste dispositivo através da tecnologia Sigfox Monarch. O SiP trabalha a partir de uma tensão de alimentação de 2.7-3.6 V e sua potência de saída de RF é programável na faixa de -30 dBm até 26 dBm. Operando com uma tensão de alimentação de 3.3V, ele consome 188.5 mA ou 23 mA para a potência de saída de RF de 22 dBm ou 12.8 dBm, em 902.2MHz e 868.13 MHz respectivamente. O dispositivo também oferece um consumo de corrente de 3 µA no modo deep sleep. O design de SiP proposto, atingiu todos os requisitos da certificação Sigfox Verified com sucesso, habilitando também a função Sigfox Monarch, representando atualmente a solução com as menores dimensões homologada para SigFox no mercado mundial, com apenas 13 mm × 13 mm × 1.1 mm
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