Mines Repository (Colorado School of Mines)
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Colemanite on calcite
No full textPhotographed by Ron Wolf.Pale yellow-white colemanite with translucent white prisms of calcite
Multifaceted analysis of algal biomolecules: from intra-organism imaging to separations of extracellular polymers
No full textIncludes bibliographical references.2024 Fall.The success of algal biotechnology hinges on the ability to efficiently cultivate algae at scale and subsequently convert the biomass into high-value products. Despite the vast potential of microalgae in applications ranging from biofuels to pharmaceuticals, significant challenges in growth, harvesting, and product conversion persist, limiting the widespread adoption of algal biotechnology. A promising avenue for addressing these challenges lies in enhancing our understanding of the culture biology, ecology, and the macromolecular composition of algae. To achieve this, the application of analytical chemistry is vital.
A critical issue in analytical practices when trying to characterize the compounds inherent to microalgae is the challenge of performing analyses in native environments, which often leads to gaps in our knowledge regarding the structures, functions, and in situ interactions of biomolecules. Specifically, ion diversity, and high ionic strengths which make up the native environment of algal microorganisms’ complicate analyses. Therefore, adopting analytical methods capable of preserving the native structures of algal macromolecules is essential for supporting the growth of the algal biotechnology sector, facilitating more efficient product development, scale-up, and application implementation.
This thesis presents a series of studies that develop and optimize analytical methodologies designed to investigate the molecular properties of microalgae and their secreted extracellular polymeric substances (EPS) while preserving their native structures and conformations. This approach facilitates the analysis of the biochemistry in a manner that closely resembles in vivo conditions.
A novel approach to lipidomic analysis of Arthrospira platensis is explored through the application of ultra-high-resolution imaging mass spectrometry. In Chapter 3, the optimization of matrix composition and application facilitated untargeted in situ lipidomics and enabled the spatial resolution of the lipidome. This spatial mapping of lipids enhances the understanding of their distribution and localization within the organism, providing insights into cellular functions and metabolic pathways.
Challenges in microalgae characterization extend beyond the microorganisms to their secreted polymers. Chapters 4 and 5 address analytical challenges in EPS characterization through the use of asymmetrical flow field-flow fractionation (AF4) coupled with multiple online detectors. An analytical pipeline consisting of AF4 separation with online multi-angle light scattering detection (MALS), followed by offline high-performance anion exchange chromatography (HPAEC) and liquid chromatography-mass spectrometry (LC-MS), was established to investigate the molecular weight distributions and aggregation behavior of these complex hydrocolloid polymers. Analysis of EPS from Chlorella vulgaris revealed different polymers with distinct primary structures and molecular weight distributions. This project further investigates polymer aggregation behavior in varying ionic environments, observing that elution patterns are influenced by ionic strength and electrolyte chaotropicity/kosmotropicity. These findings highlight how EPS physical properties change under ideal separation conditions compared to those that more closely resemble native high-ionic-strength environments, indicating larger molecular weights and a greater propensity for aggregation at native ionic strengths.
The final chapter expands upon the analytical methodology developed in Chapter 4 to analyze the structural properties of EPS. The physical and structural properties of EPS secreted by Picochlorum celeri were investigated as a function of harvest time and nutrient conditions using AF4-MALS. This work reveals for the first time the distribution of conformations that comprise EPS, demonstrating how molecular weight, size, and shape are subject to change when the polymer is produced under different physiological conditions. The data trends not only support that EPS is sensitive to environmental stimuli but also suggest that EPS is deliberately produced to serve biological functions rather than merely acting as a carbon sink when algal growth is stunted by environmental stress.
The overarching goal of this thesis is to develop analytical tools that preserve the native structures and conformations of microalgae and their macromolecules, enabling analyses that closely mimic in vivo conditions. By addressing characterization challenges and laying the groundwork for analyses compatible with the marine environment, this research advances foundational knowledge of the structure and molecular properties of microalgae and their secreted polymers.
Barriers and strategies to achieve an equitable transition to residential building electrification: a case study of Los Angeles
No full textIncludes bibliographical references.2024 Spring.Widespread residential building electrification is a key component of achieving federal, state, and local decarbonization mandates. While there has been significant research into technologies needed to achieve residential building electrification, existing research has not investigated technology deployment, and more specifically, equitable deployment in a timely manner to mitigate the worst impacts of climate change. In this dissertation, an energy justice-informed study design is used to explore viable pathways to achieve residential buildings electrification and outline the possible consequences of these pathways to ensure no household is over-burdened or left behind in this transition. First, a comparative framework is developed to analyze the scenario development process of energy models and is then applied to the development of high-quality electrification scenarios for the residential building sector. Second, a high-resolution techno-economic model is developed to calculate all costs associated with electrification upgrades. Setting a variable discount rate for each household based on income, this model compares the upgrades of varying efficiency levels for all the major electrification end uses – space heating, water heating, cooking, and clothes drying – and reports results based on income, building type, renter/owner status, and household cooling use. Lastly, two electrification supportive strategies – improved building envelope characteristics and universal access to cooling using heat pumps – are evaluated to determine if there are any synergistic benefits with the previously evaluated electrification upgrades. The work of this dissertation improves the scenario development and economic analysis of residential building electrification and provides a novel study design that incorporates the tenets of energy justice
Coal dust characterization and the impact of cutting parameters on fine particles
No full textIncludes bibliographical references.2024 Summer.Workers engaged in mechanical rock extraction may face significant long-term health risks from exposure to respirable rock dust. The purpose of this study is to describe and quantify the respirable dust generated during the cutting of coal using conical picks in varying states of wear including brand-new, moderately worn, and completely worn in a controlled laboratory setting.
Characterizing coal dust is crucial for determining appropriate respirable dust suppression levels and managing exposures throughout a pick's lifespan in underground mining and engineering operations.
In the laboratory testing program, eight coal samples were cut using three conical picks at different wear stages on a full-scale linear cutting machine (LCM). Dust samples were collected during cutting using various instruments to analyze mineralogy, particle morphologies, particle size distributions, and concentrations.
The results indicate that dust concentration and roughness increase with the rise in pick tip radii as it wears out, with each of the three picks producing distinct particle size distributions. Statistical analysis reveals that variations in fine particle size distributions and larger fragments are influenced by pick wear. However, no clear pattern or relationship was identified to suggest how the distribution of fine particles varied by pick wear levels. There were no significant
differences in the size distributions of particles within the respirable range of 0.2 to 10 microns. The aspect ratio and perimeter of particles produced by the new pick are higher, indicating that the rock is ground and broken into larger pieces as the pick radius increases
Iron meteorite
No full textPhotographed by Ron Wolf.Polished surface, metallic grey iron meteorite, Henbury, Northern Territory, Australia
Building a galactic atlas of potential cosmic ray sources
No full textCosmic rays, primarily nuclei of common elements from space, are constantly showering the entire Earth. Some have over ten million times the energy of anything produced by the Large Hadron Collider. Ultra-high-energy cosmic rays (UHECRs) are thought to be produced by supernovae, supermassive black holes, or even extragalactic sources such as gamma-ray bursts, active galactic nuclei, or unknown processes in starburst galaxies. In this project, we analyzed UHECRs that hit Earth after following a trajectory guided by the galactic magnetic field. Our work supports the hunt for the highest energy galactic cosmic ray accelerator. To do this, we used CRPropa3, a Python-driven simulation framework built to study the propagation of ultra-high-energy nuclei through the cosmos. In our simulations, we used the JF12 and UF23 galactic magnetic field models to isotropically simulate antiprotons emitted from Earth with between 1 and 10 EeV (1 EeV = 10^18 eV) of energy. By cataloging each particle interaction with one of the observer spheres placed throughout the galaxy, we generated data that works towards our ability to make predictions about which galactic sources produce the highest energy cosmic rays observed on Earth. By creating a library of potential sources featuring this data, we hope to train a machine-learning model that can utilize real-world cosmic ray data produced by the Pierre Auger Observatory to make predictions about the sources of UHECRs
Estimating remanent magnetization from aeromagnetic data for geologic applications
No full textIncludes bibliographical references.2024 Spring.Magnetic surveys involve measuring the response of the total magnetization in rocks. Total magnetization is the vector sum of induced and remanent magnetization. Induced magnetization is controlled by the inducing field and the rock's magnetic susceptibility. Remanent magnetization is a permanent magnetization in the rock. For the interpretation and modeling of magnetic data, it is common to assume induced magnetization is dominant such that remanent magnetization can be ignored; however, for some specific geologic environments, remanent magnetization is significant and affects the appearance of magnetic anomalies. Additionally, remanent magnetization carries information about the rock composition and formation history.
A remanent magnetization estimation method was tested using aeromagnetic data from the Abitibi greenstone belt to derive remanence directions of ten diabase dike anomalies. The methodology involves separating average remanent magnetization from total magnetization vector inversion models by assuming a magnetic susceptibility distribution. Eight anomalies are interpreted to have significant remanence in a direction different from the inducing field, and for these anomalies, some of the estimated remanence directions align with average paleomagnetic directions. Despite a wide range of estimated directions, the results provide insights for geological interpretation. However, the study emphasizes the inherent ambiguity and non-uniqueness of the remanence estimation methodology, presenting challenges even for isolated, compact, and steeply dipping sources.
Further study involves investigating the association between remanent magnetization and orogenic gold mineralization. Using aeromagnetic, petrophysical, and geologic data from the Timmins gold camp, the study aims to determine the significance of remanent magnetization in interpreting magnetic data from this area. Comparison between magnetization vector inversion models and remotely estimated remanence with petrophysical and geologic data from an orogenic gold deposit site indicates that remanent magnetization may either increase or decrease the total magnetization of certain rock types in the deposit area. These findings contribute to understanding the role of remanent magnetization in geological applications and magnetic modeling
Gold, chalcopyrite and pyrite in quartz
No full textPhotographed by Ron Wolf.Gold and brass-colored chalcopyrite and pyrite on quartz