Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
Browse
7 results
Search Results
Item An experimental study of drying in porous media in novel 2D micromodels with dual porosity(Montana State University - Bozeman, College of Engineering, 2024) Habib, Md Ahsan; Chairperson, Graduate Committee: Yaofa LiDrying of porous media is pervasive in numerous natural and engineering processes, such as oil recovery, CO 2 storage, and critical zone science. Drying is essentially a multiphase flow process, where the liquid phase evaporates and is displaced/replaced by the gaseous phases, as vapor diffuses out of the porous structure. In terms of pore structure and other physical characteristics like porosity and permeability, many porous matrices exhibit multi-scale heterogeneity. For instance, in critical zone, soil is often viewed as a hierarchical organization: primary particles form aggregates, which in turn form macroaggregates, effectively leading to a dual-porosity medium. Numerous activities, including gases and water transport, are known to be controlled by the resultant multiscale flow dynamics and inter-/intra-aggregate interaction during drying. However, the fundamental physics underlying drying of porous media with dual porosity is not well understood from a fluid mechanics perspective. In this work, a novel 2D microfluidic device fabrication technique has been developed. To study the multi-phase flow of air and water, emphasizing the multi-scale interaction, pore structure, and role of film flows, three distinct types of microfluidic devices have been fabricated, which bear the innovative three-layer glass-silicon- glass architecture, providing precise structural control and excellent optical access from both top and bottom. An innovative dual-magnification imaging technique has been introduced adapted for micro-PIV and epi-fluorescent microscopy which offers insightful information about the flow dynamics at both the micro- and macro-scales concurrently. In this thesis, two distinct types of experiments are outlined, focusing on diffusion-driven drying and flow-through drying, utilizing three diverse micromodels characterized by varying porous structures and distributions. The experimental results have presented the overall drying dynamics observed in different micromodels, each featuring unique porous configurations. The impact of porous geometry and external flow conditions on drying rate and associated pore-scale physics is thoroughly examined. The findings encompass a comprehensive overview of micro-macro pore interactions, as evidenced by separated saturation distribution, displacement rates, and other pertinent flow parameters. The findings have reflected the influence of pore geometry, distribution, hydraulic connectivity, and film flow on the observed effects.Item Thermalization and exciton localization in 2D semiconductors(Montana State University - Bozeman, College of Letters & Science, 2023) Strasbourg, Matthew Christopher; Chairperson, Graduate Committee: Nick Borys; This is a manuscript style paper that includes co-authored chapters.2D semiconductors are a promising class of materials to investigate for applications in the next generation of photonic devices. They can be used to generate quantum light and also exhibit correlated many-body phenomena. Many of the novel optoelectronic properties of 2D semiconductors are associated with strongly-bound hydrogen-like states known as excitons. Excitons in 2D semiconductors have binding energies on the order of 100s of meV and are stable at room temperature. At low temperatures, higher-order excitonic states such as charged excitons and biexcitons--multiple-bound excitons that are like hydrogen molecules-- and localized excitons that emit quantum light are also observed. Whether excited optically or electronically, a diversity of high-energy excitons and free carriers are produced directly after excitation. The relaxation and thermalization of these initial states influence the formation of excitons, biexcitons, and localized excitons. Here, I present work that (i) investigates the thermalization of excited states in a prototypical 2D semiconductor, monolayer (1L-) WSe2, and reports the discovery that the generation of charged biexcitons is enhanced with increasing photoexcitation energy, (ii) shows the emergence of quantum emitters (QEs) in a new 2D QE platform: 1L-WSe2 nanowrinkle arrays induced by Au nano stressors, and (iii) uses a novel method to classify the excited-state dynamics of 2D QEs and differentiate emitter populations. A suite of low-temperature energy- and time- resolved optical spectroscopies are used to conduct this work. This work shows how excited state thermalization affects the formation of exciton and biexcitons and investigates the optical properties of an emergent class of 2D quantum light emitters.Item Automatic 2D material detection and quantum emission prediction using deep learning-based models(Montana State University - Bozeman, College of Engineering, 2023) Ramezani, Fereshteh; Chairperson, Graduate Committee: Brad WhitakerThe realm of quantum engineering holds immense promise for revolutionizing technological landscapes, particularly with the advent of 2D materials in quantum device applications. The fundamental properties of these materials make them pivotal in various quantum applications. However, the progress in quantum engineering faces significant roadblocks, primarily centered around two challenges: accurate 2D material detection and understanding the random nature of quantum fluctuations. In response to the first challenge, I have successfully implemented a new deep learning pipeline to identify 2D materials in microscopic images. I have used a state-of-the-art two-stage object detector and trained it on images containing flakes of varying thickness of hexagonal boron nitride (hBN, a 2D material). The trained model achieved a high detection accuracy for the rare category of thin flakes (< or = 50 atomic layers thick). My further analysis shows that this proposed pipeline is robust against changes in color or substrate background, and could be generalized to various microscope settings. As an achievement, I have integrated my proposed method to the 2D quantum material pipeline (2D-QMaP), that has been under development by the MonArk Quantum Foundry, to provide automated capabilities that unite and accelerate the primary stages of sample preparation and device fabrication for 2D quantum materials research. My proposed algorithm has given the 2D-QMaP fully automatic real-time 2D flake detection capabilities, which has never been done effectively before. To address the second challenge, I assessed the random nature of quantum fluctuations, and I developed time series forecasting deep learning models to analyze and predict quantum emission fluctuations for the first time. My trained models can roughly follow the actual trend of the data and, under certain data processing conditions, can predict peaks and dips of the fluctuations. The ability to anticipate these fluctuations will allow physicists to harness quantum fluctuation characteristics to develop novel scientific advances in quantum computing that will greatly benefit quantum technologies. The automated 2D material identification, addressing the laborious process of flake detection, and the introduction of innovative quantum fluctuations analysis with predictive capabilities not only streamline research processes but also hold the promise of creating more stable and dependable quantum emission devices, thus significantly advancing the broader field of quantum engineering.Item Investigation of nanoscale etching and poling of lithium niobate(Montana State University - Bozeman, College of Engineering, 2014) Smith, Stacie Elizabeth; Chairperson, Graduate Committee: Wataru NakagawaThe capabilities of some nonlinear optical devices can be improved through approaches such as nano-optics. Two methods, in particular, that can enhance the wavelength conversion efficiency and versatility of current second harmonic generation (SHG) devices are creating nanoscale domain inversions (to make for efficient quasi-phase matched SHG devices at various wavelengths) and gratings in lithium niobate (to potentially achieve exact-phase matching). This thesis explores these options, creating nanoscale domain inversions and nanostructuring lithium niobate, in order to enhance current SHG devices. First, an in-depth literature survey is provided detailing the current research regarding structuring lithium niobate. Next, a description and analysis of the inductively coupled plasma reactive ion etch (ICP-RIE) etching procedures used are provided, followed by a discussion of the poling of lithium niobate using an all optical poling technique. Suggestions for continued development are presented based on the successes and failures of the procedures used for this work. The goal of this thesis is to show that lithium niobate can be nanostructured using ICP-RIE etching techniques and optical poling methods. This goal is a foundation towards the long-term goal of building more efficient nonlinear optical devices. Nanostructuring lithium niobate suggests that improved nonlinear optical devices can be made in the future, by means of nanoscale domain inversions for quasi-phase matching or nanoengineered gratings intended for exact-phase matching.Item Engineering bacteriophage P22 as a nanomaterial(Montana State University - Bozeman, College of Letters & Science, 2013) O'Neil, Alison Linsley; Chairperson, Graduate Committee: Trevor Douglas; Courtney Reichhardt, Benjamin Johnson, Peter E. Prevelige and Trevor Douglas were co-authors of the article, 'Genetically programmed in vivo packaging and controlled release of protein cargo from bacteriophage P22' in the journal 'Angewandte chemie international edition' which is contained within this thesis.; Gautam Basu, Peter E. Prevelige and Trevor Douglas were co-authors of the article, 'Co-confinement of fluorescent proteins: spatially enforced communication of GFP and mCherry encapsulated within the P22 capsid' in the journal 'Biomacromolecules' which is contained within this thesis.; Peter E. Prevelige and Trevor Douglas were co-authors of the article, 'Encapsulation within the P22 capsid greatly improves the stability of a phosphotriesterase' submitted to the journal 'Advanced Functional Materials' which is contained within this thesis.The precise architectures of viruses and virus-like particles are highly advantageous in synthetic materials applications. These nano-size compartments are perfectly suited to act as containers of designed cargo. Not only can these nanocontainers be harnessed as active materials, but they can be exploited for examining the effects of in vivo "cell-like" crowding and confinement on the properties of the encapsulated cargo. The high concentration of many different types of mutually volume excluding macromolecules in the cell causes it to be a crowded and confining environment in which to carry out reactions. Herein, the molecular design of the bacteriophage P22 encapsulation system is described and utilized for the synthesis of active nanomaterials and to explore the effect of encapsulation on the entrapped proteins' properties. In the designed system, any gene can be inserted and results in the fusion of the insert to a truncated form of the P22 scaffold protein. This scaffold protein fusion templates the spontaneous in vivo assembly of P22 capsids and also acts as an encapsulation signal. Once encapsulated, we can examine how crowding and confinement affect inter-molecular communication and activity of the cargo molecules. The P22 system is unique in that the capsid morphology can be altered, without losing the encapsulated cargo, resulting in a doubling of the capsid volume. Thus, the encapsulated fusions can be examined at two different internal concentrations. The packaged capsids contain up to 300 copies of fusion and fill more than 24% of the internal volume with the internal concentration of the fusions in the millimolar range. Not only are these fusions densely and efficiently packaged, but they retain their activity. Described herein is the packaging of fluorescent proteins, enzymes, and active peptides. In all cases, it is shown that the enforced proximity via encapsulation greatly affects the fusions activity compared to the fusion free in solution. To expand the utility of the P22 capsid as a nanomaterial, the inherent asymmetry implored by the portal complex has also been exploited. The P22 encapsulation system has proved to be an effective and versatile vehicle for nanomaterials design.Item A study of polymeric platinum(II) compounds and Nanoscale materials(Montana State University - Bozeman, College of Letters & Science, 2004) Anderson, Bernard Marshall; Chairperson, Graduate Committee: Edwin H. Abbott; Lee H. Spangler (co-chair)The photophysical and structural properties of the tetra-u- pyrophosphitodiplatinate (2-) anion have been well studied in the past. One such analogue of this compound is a phosphorescent red compound of unknown structure. A new synthesis route has been was found for both the tetra-u- pyrophosphitodiplatinate (2-) and the red anionic compounds. By synthesizing the pyrophosphorus ligand outright and reacting that with tetrachloroplatinate (2-) either the tetra-u-pyrophosphitodiplatinate (2-) or the red anionic compounds can be synthesized depending on the amount of the phosphorus acid that is present. It was found from light scattering measurements and with the usage of 31P NMR spectroscopy that the red platinum(II) compound is structurally different than that of tetra-u-pyrophosphitodiplatinate (2-). A revised synthetic route was made for the synthesis of pyrophosphorus acid which was found to be an insoluble, highly reactive ligand. Reactions of pyrophosphorus acid with normal alcohols led to the formation of phosphorus acid and the corresponding monoalkylated phosphorus acid.Item Nanocomposites : a study of theoretical micromechanical behavior using finite element analysis(Montana State University - Bozeman, College of Engineering, 2009) Milliren, Eric Carlton; Chairperson, Graduate Committee: Christopher H. M. JenkinsCurrent research in nanotechnology has produced an increasing number of possibilities for advanced materials. Among those materials with potential advanced mechanical properties are fiber-reinforced composite laminates that utilize nanoscale fiber diameters. Through a combination of studying classic micromechanical models and modern computer-aided finite element analysis (FEA), the advantages for utilizing these nanofibers in advanced structural applications, such as space mirror backings, was investigated. The approach for modeling these composite structures was that of a Representative Volume Element (RVE). Using the program ABAQUS/CAE, a RVE was created with the goals of accurately comparing to the shear lag theory, effectively incorporating "interphase" zones that bond the constituents, and demonstrating effects of down-scaling fiber diameter. In this thesis, the progression of the ABAQUS model is thoroughly covered as it developed into a verified model correlating with the shear lag theory. The model produced was capable of utilizing interphase if desired, and was capable of off-axis loading scenarios. A MathCAD program was written in order to employ the published theoretical techniques, which were then compared to the FEA results for verification. The FEA model was found to work well in conjunction with the theory explored using MathCAD, after which the nanofiber FEA model showed some clear advantages over a conventional-sized model, specifically an increase in strength of the composite RVE. Finally, it was determined that the interfacial bonding strength plays a large role in the structure of the interphase zone, and thus the overall strength of the composite.