Recent Submissions

  • Development of calcium and oxygen nanosensors for in-vivo diagnostics

    Cash, Kevin J.; Mendonsa, Adrian; Isbell, Sydney
    Diagnostic tests to determine analyte concentration can be repetitive and require extensive training for proper analysis. To address these limitations, we developed two ratiometric nanosensors (calcium (Ca2+) and oxygen (O2)) which could be implemented in-vivo to give insight into biological functions such as nerve signaling and cellular respiration. The Ca2+ nanosensors’ optical properties (fluorescence and absorbance) vary to reflect the surrounding Ca2+ concentration. These sensors are selective to Ca2+ over other biologically relevant cations (Mg2+, Na+, K+) and show a sensitivity to Ca2+ at concentrations as low as 100 µM. The O2 nanosensor is composed of two dyes encapsulated in a hydrophobic PVC matrix. The O2 sensitive dye, platinum octaethylporphyrin (PtOEP), shows a decrease in luminescence with increasing oxygen concentrations. Whereas, the reference dye, DiA, has no O2 sensitivity. These O2 sensors are reversible and have a detection range that spans from anoxic (0% O2) to atmospheric conditions (21% O2). While the Ca2+ and O2 sensors showed functionality in in-vitro studies, testing these sensors in-vivo will determine their effectiveness as a long-term diagnostic aid.
  • Harnessing geomicrobial respiration in engineered wetlands for pre-treatment of brackish waters

    Vega, Michael A. P.; Vanzin, Gary; Gidley, Nicholas; Wang, Weishi; Yang, Zhaoxun; Sharp, Jonathan O.; Garza, Max
    As arid regions become increasingly vulnerable to climate change, brackish groundwater offers the potential to supplement existing water resources, particularly for inland states such as Colorado. However, Brackish Water Reverse Osmosis (BWRO), presents a unique set of challenges that include membrane fouling due to elevated concentrations of inorganic precipitates and the production of substantial quantities of brine concentrate that often harbor heavy metal contamination. A possible mechanism for increasing BWRO efficacy is the use of shallow, unit process open water (UPOW) wetlands colonized by diatoms for biological pre-treatment. The photosynthetic diel (day/night) cycling in the wetlands, which passively increases pH during the day as carbonate is consumed, mimics traditional water treatment to create favorable, alkaline conditions needed for metal precipitation, but without chemical additions. Through various processes, the microbial mat (biomat) that naturally forms within UPOW wetlands can potentially reduce scalants (calcium, magnesium, and sulfates), as well as oxidize challenging constituents, such as arsenite, from the water prior to membrane treatment. Therefore, laboratory-scale UPOW wetlands were created using biomat harvested from an operational field-scale constructed wetland and challenged with synthetic brackish water. Preliminary results suggest that the reduction of scalant concentrations and oxidation of heavy metals can prevent excess membrane fouling and enhance RO rejection. This approach promotes environmental sustainability by eliminating the need for chemical additions, reducing brine concentrate volumes, and by decreasing energy and labor requirements. Findings may ultimately help address technoeconomic issues associated with BWRO and help guide further investigations into biological pre-treatment of brackish water.
  • Hip-belt load sharing reduces peak shoulder pressure across walking slopes during heavy load carriage

    Rizeq, Hedaya N.; Slider, Amy; Sessoms, Pinata H.; Sturdy, Jordan T.; Silverman, Anne K.; Inge, Madeline M.
    Musculoskeletal injury to the spine and lower back resulting from heavy load carriage (30–40 kg) is common among military service members. Static peak pressure is a reliable parameter for predicting discomfort. The effect of using a hip belt on shoulder pressure is not well understood. This study aimed to quantify the pressure under shoulder straps when carrying a backpack with and without a hip belt. Three military service members wore a helmet and body armor (~6.5kg) and carried a backpack in two attachment conditions: (1) entirely shoulder borne, and (2) with a hip-belt engaged, all totaling 40% body weight. Participants walked at three different slope conditions (10° downhill, level, and 10° uphill) at 1.15 m/s for each backpack condition. Peak pressure across both shoulders was extracted from each condition. Shoulder borne peak pressure (down: 36.33 kPa; level: 37.67 kPa; up: 36.67 kPa) was greater than the hip belt (down: 29.67 kPa; level: 24.67 kPa; up: 29.67 kPa). Walking with the hip belt engaged compared with the shoulder borne-only backpack resulted in ~9 kPa smaller peak shoulder pressure on average across all three slopes, indicating that peak pressure is reduced when using a hip belt, although greater participant numbers are needed to confirm these results.
  • Optimization of space nuclear reactor shielding through computational analysis

    King, Jeffrey C.; Hoffmann, Madeline
    Nuclear reactors emit ionizing radiation that can be harmful to people and electronic equipment. Shielding materials that attenuate this radiation can be a significant fraction of the mass of a space nuclear reactor power system. Optimizing space reactor shielding geometry and composition allows the design of shields that can reduce neutron and gamma-ray doses from the reactor to an acceptable using the minimum amount of shielding material. This project generated a Python 3.10 script that uses OpenMC to test arbitrary compositions of different materials in various layers and geometries to optimize a shield for space reactor applications. OpenMC is an open-source Monte Carlo-based neutron transport code that probabilistically models the movement of neutrons and photons as they interact with a user-specified environment. When finished, the program will analyze combinations of neutron absorbers (lithium hydride, enriched lithium hydride, and boron carbide) and photon absorbers (tungsten and depleted uranium) arranged in different layers and thicknesses to determine their ability to reduce dose from a hypothetical space reactor to 5 mrem/hr at a point 10 m from the surface of the payload-side of the shield. The shield will be modeled as two opposed truncated cones with a total thickness of 50 cm. The cones will be tested with in multiple configurations to determine the optimal geometry to minimize mass while meeting the target dose. Future investigations will expand the model to include total thickness optimizations and a more detailed dose analysis over a target area.
  • Backpack motion relative to the torso is affected by walking slope

    Rizeq, Hedaya N.; Slider, Amy; Sessoms, Pinata H.; Sturdy, Jordan T.; Silverman, Anne K.; Giltinan, Kagan P.
    Military backpacks are equipped with hip belts, which have been shown to support 30% of the vertical force from the backpack. These belts do not offload enough force to prevent tissue strain on the shoulders, which can lead to discomfort and injury. Stiffness and damping in a backpack’s straps and connections can affect backpack movement, which may be related to tissue strain, when walking. However, the effects of using a hip belt on relative motion between the backpack and the wearer are unclear. Four active duty military participants walked at 1.15 m/s on uphill (+10¬∞), downhill (‚àí10¬∞), and level (0¬∞) slopes. They wore body armor with helmet and backpack using only the shoulder straps (Shoulder) or with the hip belt secured (Hip Belt), carrying 40% body weight total. 3D motion of the backpack and torso was obtained with optical motion capture. Maxima and minima of backpack-torso displacement were calculated in each walking condition. The difference between sequential maxima and minima were used to obtain ranges of vertical backpack-torso displacement during each walking condition for each participant. The hip-belt did not influence relative vertical motion of the backpack. The pack and slope did affect the horizontal relative displacement (p = .086). The greatest relative displacement for anterior/posterior direction was 7.7mm, and vertical direction was 19.9mm. Horizontal displacement was not affected by slope alone during Hip Belt, but was affected during Shoulder (p = .056). The vertical relative displacement was affected by slope, p = .007.
  • Low-cost modular and flexible laser source

    Adams, Daniel; Spoor, Henry
    This project investigates the feasibility of producing high-quality, high-reliability laser beams from traditional handheld laser pointers. The goals of this project included understanding the fundamental principles and functionality of a handheld laser pointer as well as conversion of said laser pointer to a setup that could be used in a research-level capacity. To achieve these goals, handheld lasers were disassembled to their component parts, and extensive testing was performed on the maximum capabilities of the laser pointers. Data was collected on the maximum supplied current the laser diode could withstand, the viability of creating a tunable intensity laser and the potential for making a reproducible product. In the testing process, the converted laser pointers were found to be reliable if constrained to a limited current. Additionally, the laser beam was successfully made to have a tunable intensity by varying the supplied current. Additional testing will be performed to determine the lifespan of the converted laser pointer as well as the reproducibility of the project for use in a research setting.
  • Relationship between hand grip strength and mediolateral torso movement in five times sit-to-stand, The

    Silverman, Anne K.; Miller, Michael F.; Beebe, Claire A.
    Balance regulation during daily activities is a key component of movement performance and fall risk as we age. There is a well-defined correlation between lower limb muscle strength and hand grip strength (HGS) and lower limb muscle strength is critical for balance regulation. The Five Times Sit-To-Stand test (5xSTS) is an evaluation of muscle strength and mobility during transitions that helps identify individuals at risk of fall. Thus, we aimed to determine if mediolateral movement biomechanics during the 5xSTS test, which are important for balance performance, were correlated with HGS. Ten young and healthy participants completed a 5xSTS trial where they rose from the seat to a standing position and returned to the seat five consecutive times as quickly as possible. We performed a Pearson correlation analysis (α ± < 0.05) between range of mediolateral torso center of mass (COM) displacement, dominant HGS and time to completion of 5xSTS. There was not a significant correlation between time to completion and HGS (rho (ρ) = -0.515, p = 0.127). A moderate negative correlation that approached significance (0.05 < p < 0.10) was found between mediolateral torso COM displacement and HGS (rho (ρ) = -0.558, p = 0.094). There was no correlation between mediolateral torso COM displacement and time to completion (rho (ρ) = 0.143, p = 0.693). HGS could help indicate mediolateral balance performance during 5xSTS and improve the lower limb strength assessment due to its correlation with torso motion. Recording dominant HGS alongside 5xSTS completion time may provide insight into mediolateral dynamic balance performance.
  • Intelligent prediction of traffic conditions via integrated data-driven crowdsourcing and learning

    Seo, Hoon; Taylor, Ethan; Wang, Hua; Rippey, Caroline
    Intelligent Transportation Systems (ITS) are gaining popularity among governments, businesses, and individuals due to their potential to make travel safer and more efficient. Machine learning for traffic prediction has emerged as a promising subfield of ITS, with the potential to aid in routing planning, congestion management, and urban development. Traffic infrastructure and mobile devices collect large amounts of heterogeneous data that can be used to predict traffic conditions, including real-time traffic data such as traffic camera images, speed measurements, and volume counts, as well as long-term static data such as speed limits, road conditions, and surrounding geography and infrastructure. Despite the availability of traffic data, many current machine learning models struggle to handle the wide variety of data types and to address both temporal aspects of real-time data and spatial aspects of long-term static data. To address this, we propose a new enrichment learning model that integrates dynamic data containing varying numbers of instances with static data to create an enriched fixed-length vector which can be used with other machine learning methods to improve performance and identify regions important for prediction. Results show that this novel enrichment learning model can improve the performance of traditional machine learning methods in the task of predicting future traffic speeds.
  • Changes in extracellular matrix stiffness affect pancreatic islet function

    Farnsworth, Nikki; Johansen, Chelsea; Sela, Amit
    In the pancreas, the islet is surrounded by a specialized protein scaffold known as the extracellular matrix (ECM) that regulates cell survival and insulin secretion. Little is known about how the properties of the pancreas microenvironment, like matrix stiffness, regulate islet function in health and disease. Previous studies have shown that tissue stiffness in muscle cells regulates phosphofructokinase (PFK) activity. The mechanisms underlying mechanotransduction regulation of insulin secretion have not been well studied in the β-cell and a connection between metabolism and mechanotransduction has never been studied in intact islets. We hypothesize that increasing matrix stiffness will increase islet glucose sensitivity by increasing PFK activity. Our lab has developed a 3D reverse thermal gel (RTG) system that allows us to mimic the islet microenvironment and to investigate how the environment affects islet function. To determine the effect of changes in ECM stiffness on islet function we encapsulated mouse islets in the RTG with increasing stiffness as determined by rheological analysis. Glucose-stimulated insulin secretion, PFK activity, and PFK expression was measured after 24 hours of culture. We found that increasing RTG wt% yielded increasing stiffness at 40°C. Insulin secretion increased as the matrix stiffness increased in basal and high glucose conditions. Insulin secretion at high glucose normalized to low glucose (stimulation index) decreases with matrix stiffness indicating dysfunction to insulin secretion. PFK activity increased in islets encapsulated in stiffer RTGs. Our results provide insight into how changes in ECM stiffness contribute to islet dysfunction.
  • Ankle muscle strength affects muscle forces during double leg hopping

    Daley, Monica A.; McNitt-Gray, Jill; Silverman, Anne K.; Miller, Michael F.; Vargas, Brooklyn L.
    Falls are a primary cause of morbidity and mortality in older adults, with dynamic balance decline often being the precursor to a fall. Declining lower limb strength has been linked to dynamic balance decline. Therefore, this study will evaluate the effect of ankle muscle weakness on muscle control and coordination of double leg hopping, a task that requires precise dynamic balance control. A healthy adult performed ten continuous double leg hops. Motion capture and ground reaction forces were collected. A model was developed in Visual3D (C-Motion, Inc.), and inverse kinematics (IK) of three hops were computed. The GRFs along with the IK solutions were exported to OpenSim v 4.4 and applied to a scaled musculoskeletal model. A Residual Reduction Algorithm (RRA) improved dynamic consistency. Computed Muscle Control (CMC) then determined the needed muscle excitation patterns. A weakened model was developed with reduced maximum isometric force of the MG, LG, and SOL to represent aging. Peak dynamic force from MG and SOL decreased by 16% and 3% respectively in the weakened model, while the LG increased by 16%, compensating for MG force deficits. Several agonist muscles in the weakened model increased their peak force output, suggesting they are compensating for the weakened MG, LG, and SOL. The ankle reserve actuator peak torque increased by 135% in the weakened model. These findings indicate ankle muscle weakness associated with aging affects hopping strategy and muscle recruitment. Strength should be preserved to maintain movement and prevent dynamic balance decline.
  • Glaciers in the south: a comprehensive framework for evaluating public school district capacities for cryosphere education

    Reddy, Elizabeth; Siegfried, Matthew; Verboncoeur, Hannah; Miller, Ashleigh
    Rising sea levels have disproportionately large impacts on Southern coastal regions of the United States, and to a greater degree among communities therein affected by socioeconomic inequalities. Despite this, research in one of the leading causes of global sea level rise, melting ice (i.e., the cryosphere), is largely left behind in the curricula of public middle and high school institutions throughout these southern states. As rates of sea level rise continue to increase, an assessment of educational capacities within the context of present-day access to climate and cryosphere education in the United States becomes increasingly important. In this study, we apply an inductive coding method to current public-school curricula at the "8th to 12th" grade levels to assess the capacities of Southern schools to support strengthened cryosphere and sea level rise education. This developed framework can be applied to school systems across the United States and ranks availability of access, capacities form and connections to cryosphere and sea level rise education. The results of this study indicate a great potential to connect sea level rise and cryosphere education to the impacts and experiences of coastal communities in the United States, as well as capacities to forge new collaborations between funded university-level research centers and local communities to support educational access. Future work will quantify the identified capacities within southern public school science curricula in an actionable manner for use by Boards of Education, politicians, and scientists in sea level rise and cryospheric science spaces.
  • Understanding charge carrier mobility in Hg₂GeTe₄

    Qu, Jiaxing; Ciesielski, Kamil; Ertekin, Elif; Toberer, Eric; Porter, Claire E.
    High charge carrier mobility in semiconductor materials is desirable across a broad range of fields ranging from light-emitting devices to thermoelectrics. Electronic mobility is driven by both the intrinsic electronic band structure of the material as well as the energy dependent electron scattering mechanisms. Semiconductors with excellent mobility span a large chemical space: transparent conductor CdO, topological insulator HgTe, and Zintl compound KAlSb4. Therefore, engineering high mobility from chemistry alone is difficult if not impossible. Relating chemistry and synthetic processing to their impact on mobility is highly desirable, but experimentally difficult. Adding a fourth thermomagnetic measurement, the Nernst coefficient, to the traditional thermoelectric transport measurement suite (resistivity, Hall coefficient, Seebeck), allows the experimentalist to derive a carrier lifetime/scattering parameter as a function of temperature. We design a custom apparatus to measure the Nernst effect and perform initial model measurements to address the question of what scattering mechanisms limit the mobility of several potential thermoelectric materials. In our design, we test different sample and sample holder geometries to optimize reproducibility. For the model materials we measure the Nernst signal at low magnetic field (µB < 1) in addition to traditional Hall coefficient, Seebeck, and resistivity. We employ the method of four coefficients to determine four electronic parameters: µ, n, m*DOS, and λ (scattering factor). By utilizing the method of four coefficients, we can decouple effects from electronic band structure from energy-dependent scattering effects, and therefore design optimal thermoelectric materials and validate the scattering predictions from computational methods.
  • Applications of post-quantum cryptography - survey and application of machine learning

    Moorman, Jay; Osborne, Mack W.
    Quantum Computing poses a considerable threat in the world of cyber security. Policy makers are largely unprepared for a post-quantum world, significantly due to a lack of understanding and awareness. The goal of this paper is to improve understanding and provide a new and effective way to analyze post-quantum cryptography, for researchers and security engineers alike. This is done by providing a background of quantum computing, a survey of the state of technologies and relevant policies, and a novel application of machine learning to perform analysis of quantum-ready encryption. The machine learning research will provide a Multinominal Naïve Bayes for discrete analysis of the RSA and CRYSTAL-Kyber encryptions.
  • Reversible solid oxide electrochemical system as seasonal energy storage in ultra-high renewable energy grid scenarios

    Guerra, Omar J.; Braun, Robert J.; Thatte, Amogh A.
    The electrochemical production of hydrogen by surplus variable renewable energy (VRE) can reduce the cost of future energy systems. Supported by favorable electric grid conditions and increasing research and development investments, large-scale power-to-gas (P2G) plants are increasingly being deployed worldwide. Techno-economic and energy planning analyses involving hydrogen production and energy storage typically take either "price-taker" or "production cost" modeling approaches, with the "price-taker" approach being predominant. However, given the increasing development and deployment of P2G plants, price-taker models based on the fundamental assumption that the presence of an individual P2G plant will not affect electric grid conditions are no longer valid. To address this issue, the present research uses a production cost model that minimizes the electric grid's total energy generation cost to capture the benefits of operating a utility-scale, grid-connected reversible electrolyzer plant. A generic methodology to analyze seasonal energy storage operating in an ultra-high VRE grid (> 90% integration levels) is developed, and a newly developed seasonal storage modeling methodology is then implemented to analyze the integration of a reversible solid-oxide electrolyzer system with such highly penetrated VRE grid scenarios. This research shows that the reversible solid-oxide system operating in an ultra-high VRE grid can reduce the annual electricity generation cost by 5-15% (subject to grid conditions).
  • Integrating full-field optical methods, inverse techniques and traditional mechanical testing for damage tolerancing in CFRPs under impact fatigue

    Lamberson, Leslie; Mendoza, Isabella
    Composite structures are susceptible to transverse loading due to their inherent layered structure, particularly when under impact. Under low energy repetitive impacts (LERI), little is understood regarding damage mechanisms, damage accumulation, and the post-mortem global response of the composite material under different loading configurations. In this study, we examine carbon fiber-reinforced composite (CFRC) plates subjected to low energy repetitive impacts of 2 J to investigate their behavior under impact fatigue. Post-mortem specimens are then investigated using three main methods: digital image correlation (DIC), the virtual fields method (VFM) and compression-after-impact (CAI) tests. DIC is used to extract surface kinematics under an applied static load to observe the evolution of strain fields under bending as the number of impacts accumulate. This data is then used as input for VFM analysis which is used to reveal local gaps in mechanical equilibrium, allowing it to be used as an indicator of damage. Next, ASTM standard CAI tests are performed on the impacted specimens to compare ultimate compression strength values. X-ray computed tomography (XCT) is also used to corroborate damage detection provided by the equilibrium gap method and identify catastrophic microstructural damage pre-cursors. Using quasi-isotropic 8-ply CFRC plates, XCT results showed that interlaminar cracking appeared in as little as 10 impacts. At 100 impacts, extensive matrix cracking and delaminations were observed. After 300 impacts, severe delaminations were imaged using XCT, while barely visible surface cracks were imaged on the rear face of the specimen.
  • Quantifying channel network morphometrics at Jezero and Eberswalde craters

    Henry, Jack; Plink-Björklund, Piret; Gezovich, Luke J.
    Ancient lakes on Mars and the river deltas which occur along their shorelines offer attractive targets for mission landing sites due to their habitability and high biosignature preservation potential. Deltas are promising targets for finding organic molecules and other signatures of life because on Earth deltas have biodiverse and rich ecosystems. Furthermore, the presence of deltas are used to map paleoshorelines for ancient oceans and lakes on Mars. For instance, Jezero Crater was chosen as the NASA Perseverance landing site because the fan-shaped channel network at the edge of the crater was interpreted as a delta. However, on Earth, fan-shaped channel networks may also form in fluvial fans that are inland terrestrial landforms that can form 1000s of kilometers from shorelines. We demonstrate that morphometric criteria are needed to accurately identify fan-shaped landforms for potential future landing sites. The goal of this research project is to differentiate deltas and fluvial fans on Mars by quantifying fan-shaped paleochannel network morphometrics. To accomplish this, we map Martian fan-shaped paleochannel networks using images from the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experience (HiRISE) and Contex Camera (CTX) photographs in combination with ArcGIS. Morphometric data is statistically analyzed using python and other open-source data visualization libraries. The outcomes of this project will improve our ability to choose appropriate landing sites in search of life, and to map paleo-shorelines on Mars. Preliminary results suggest the channel network at Jezero resembles a fluvial fan, while the landform at Eberswalde crater resembles a delta. Fluvial fan formation has been linked to large sediment and water discharges, and to fluctuations in discharge as a result of highly seasonal precipitation in climatic settings that promote marked seasonal and interannual hydrological changes, leading to variable discharge regimes and exceptional flood events. Alternative evidence is required to identify paleo-shorelines as fluvial fans may also form along shorelines. On Earth, fluvial fans are less sensitive to sea-level rise and coastal hazards than deltas and react differently from deltas due to changing sea levels.
  • Failure conditions and triggers of the Achoma landslide, central Andes region, Arequipa Peru

    Santi, Paul M. (Paul Michael), 1964-; Lemus, Oscar
    The Colca River valley in southern Peru is the longest waterway of the Pacific Peruvian hydrologic basins, starting in the Perú Altiplano, and crossing the western Andean Cordillera to the Pacific Ocean. The area has been regularly impacted by large landslides of the valley slopes, and geologic evidence documents intense, recurrent, and catastrophic events, like landslides, debris avalanches, and floods. On June 18, 2020, more than 5,400,000 m3 of soil and weak rock slid into the Colca River valley near the town of Achoma. The rotational slide involved 40 hectares of land that was displaced 500 meters. The event destroyed the agricultural land, impacting the economy of many families, and the displaced material over the Colca River created a dam that increased the risk of flooding for the towns upstream. The exact factors that led to the landslide in Achoma, including triggering factors, are uncertain. The activity of farms, most of which are currently irrigated or have been irrigated in the past, and the presence of a large water transportation canal upslope of the landslide are the most likely causes of the increase in ground-water levels leading to failure. The purpose of this work is test various groundwater and infiltration scenarios to estimate the amount of water involved in the destabilization and triggering of the Achoma landslide, using numerical simulation of changing groundwater conditions. While not definitive, our early work indicates that, even though the landslide occurred during the dry season and before the irrigation began for the year, we cannot yet rule out irrigation as a contributing factor. On the other hand, increasing ground-water levels from leakage from the water conveyance canal appears to be a necessary component to cause slope failure.
  • Elucidating algal extracellular polymeric substance structures with asymmetrical flow field-flow fractionation and light scattering

    Laurens, Lieve M. L.; Williams, S. Kim R.; Lesco, Kaitlin C.; Plavchak, Christine
    Extracellular polymeric substances (EPS) from algae are complex, secreted, aquatic heteropolymers (comprised of carbohydrate and proteins), possibly functioning as carbon sinks. EPS has tremendous potential to be utilized as high-value coproducts, e.g. hydrocolloids or biobased polymers, and playing a significant role in the overall aquatic ecology (feeding a healthy microbiome) during cultivation. Unfortunately, the structural elucidation of these polymers is elusive in literature making the design of custom applications difficult. We must characterize these polymers on a chemical, structural, and physical level to understand their biological significance and industrial potential. The first step is to reduce the complexity of EPS with a size-based separation such as asymmetrical flow field-flow fractionation (AF4). When coupled to multi-angle light scattering (MALS), AF4 can provide the separation and characterization needed to determine the molecular weight and size of different populations in the sample. This work evaluates the different size populations present in the EPS of Chlorella vulgaris using AF4-MALS. Fractions were collected and analyzed to probe differences in compositional analyses between the different size populations. The separation investigates aggregate behavior at different ionic strengths to better understand the interactions of these biopolymers in their native, higher salinity, environments. The EPS of C. vulgaris has demonstrated diverse molecular weight populations ranging from 4x104 – 3x108 Daltons. We observed a reduction of fractogram features at high ionic strength indicating polymer aggregation. This work aims to be the first step in complete structural determination of EPS while probing fundamental separation observations on polymer behavior at different salt concentrations.
  • Temporal downscaling for solar radiation

    Nychka, Douglas; Bandyopadhyay, Soutir; Bailey, Maggie D.
    Global and regional climate model projections are useful for gauging future patterns of climate variables, including solar radiation, but data from these models is often too spatio-temporally course for local use. Within the context of solar radiation, the changing climate may have an effect on photo-voltaic (PV) production, especially as the PV industry moves to extend plant lifetimes to 50 years. Predicting PV production while taking into account a changing climate requires data at a resolution that is useful for building PV plants. Temporal and spatial downscaling of solar radiation data is widely studied. We present a novel method to downscale global horizontal irradiance (GHI) data from daily averages to hourly profiles, while maintaining spatial correlation of parameters characterizing the diurnal profile of GHI. The method focuses on the use of a diurnal template which can be shifted and scaled according to the time or year and location. Variability in the profile is later added to account for clouds if the daily average value indicates a cloudy day. This analysis is applied to data from the National Solar Radiation Database housed at the National Renewable Energy Lab and a case study of the mentioned methods over California is presented. This method will later be applied to future projections of solar radiation from bias-corrected regional climate models to create a massive dataset that projects solar radiation for future years across the United States.
  • Power harvesting using FDTD for 5G biomedical applications

    Elsherbeni, Atef Z.; Lumnitzer, Rachel S.
    The finite difference time domain (FDTD) method is well characterized for various simulations of 5G applications. Biomedical applications are one notable area of research, particularly wearable devices for remotely monitoring patients. The current simulations are conducted at 28 and 29 GHz within the n257 and n261 bands of the 5G allocation spectrum [1]. Higher frequencies allow for compact designs, higher data rates, and more capacity, however, they also have higher path loss, increased sensitivity to fabrication, potential health effects, and require efficiency of power transfer for wirelessly charging without the need for batteries [1]. Despite these challenges, there is a need for research and demonstrated performance of 5G wearable devices. The FDTD is used to enhance the transfer of power for wearable antenna on human wrist using combination of dielectric cylinders at the surface of the skin [2]. A 2D model of the wrist tissues is used with the traditional FDTD algorithm to solve for the E-field distribution within the first tissue layer. A 3D wrist model is used with the dispersive FDTD formulation Debye permittivity model to accurately simulate more practical layouts [3]. Our 2D optimized model results show a potential gain of over 8 dB for 28 and 29 GHz which is higher by at least 2 dB over existing similar analysis showing 6 dB of gain [2]. The more practical 3D simulations show a potential gain of 6 dB and 3 dB for 28 and 29 GHz, respectively.

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