Physical Sciences and Mathematics Commons^™

Supramolecular Pi-Donor/Acceptor Arrays Based On Redox-Active Metal-Organic Coordination Assemblies, Paola Benavides

All Dissertations

Coordination-driven self-assembly is an attractive strategy for constructing thermodynamically stable supramolecular coordination complexes, ranging from discrete metallacycles and cages to infinite coordination polymers and metal-organic frameworks for a variety of applications.

Chapter 1 discusses strategies for preparing supramolecular charge-transfer π-donor/acceptor assemblies and their potential applications.

Chapter 2 demonstrates that tricomponent self-assembly method, which was believed to yield 3D-cages, based on tetrapyridyl porphyrin (M’TPP, M’ = Zn or H₂), dicarboxylate ligands (XDC), and caped cis-Pt(II) corners, actually yields 2D-bowties featuring an M’TPP core and two parallel XDC linkers held together by four heteroligated PtII(N,O) corners. The 2D-bowties showed …

Designing Noncentrosymmetric Multifunctional Materials, Ebube Oyeka

All Dissertations

Noncentrosymmetric (NCS) materials with crystal lattices lacking spatial inversion symmetry display a wide range of exciting functionalities. This dissertation covers two classes of functional NCS materials: magnetic skyrmion-host compounds and multifunctional materials. Magnetic skyrmion and multifunctional materials combining optical and magnetic responses are providing avenues for developing and optimizing the performance of electronic devices that can have uses in memory storage, laser technology, medicine, sensors, etc. The formation of skyrmions is driven by asymmetric Dzyaloshinskii–Moriya (DM) interaction facilitated by broken spatial inversion symmetry and large spin-orbit coupling (SOC), while multiple functionalities arise when spin carriers and optical chromophores are optimally …

Advancements In Fluid Simulation Through Enhanced Conservation Schemes, Sean Ingimarson

All Dissertations

To better understand and solve problems involving the natural phenomenon of fluid and air flows, one must understand the Navier-Stokes equations. Branching several different fields including engineering, chemistry, physics, etc., these are among the most important equations in mathematics. However, these equations do not have analytic solutions save for trivial solutions. Hence researchers have striven to make advancements in varieties of numerical models and simulations. With many variations of numerical models of the Navier-Stokes equations, many lose important physical meaningfulness. In particular, many finite element schemes do not conserve energy, momentum, or angular momentum. In this thesis, we will study …

Boosting Just-In-Time Defect Prediction With Specific Features Of C/C++ Programming Languages In Code Changes, Chao Ni, Xiaodan Xu, Kaiwen Yang, David Lo

Research Collection School Of Computing and Information Systems

Just-in-time (JIT) defect prediction can identify changes as defect-inducing ones or clean ones and many approaches are proposed based on several programming language-independent change-level features. However, different programming languages have different characteristics and consequently may affect the quality of software projects. Meanwhile, the C programming language, one of the most popular ones, is widely used to develop foundation applications (i.e., operating system, database, compiler, etc.) in IT companies and its change-level characteristics on project quality have not been fully investigated. Additionally, whether open-source C projects have similar important features to commercial projects has not been studied much.To address the aforementioned …

Contrabert: Enhancing Code Pre-Trained Models Via Contrastive Learning, Shangqing Liu, Bozhi Wu, Xiaofei Xie, Guozhu Meng, Yang. Liu

Research Collection School Of Computing and Information Systems

Large-scale pre-trained models such as CodeBERT, GraphCodeBERT have earned widespread attention from both academia and industry. Attributed to the superior ability in code representation, they have been further applied in multiple downstream tasks such as clone detection, code search and code translation. However, it is also observed that these state-of-the-art pre-trained models are susceptible to adversarial attacks. The performance of these pre-trained models drops significantly with simple perturbations such as renaming variable names. This weakness may be inherited by their downstream models and thereby amplified at an unprecedented scale. To this end, we propose an approach namely ContraBERT that aims …

Phylogeny And Taxonomy Of Himerometroidea (Echinodermata: Crinoidea), Kristian H. Taylor, Gregory W. Rouse, Charles G. Messing

Marine & Environmental Sciences Faculty Articles

Himerometroidea is a clade of chiefly shallow-water, tropical, feather-star crinoids that is currently divided, based on morphology, into four families comprising 119 extant species in 31 genera. Our molecular phylogenetic results, based on three mitochondrial (CO1, 16S, CytB) and two nuclear (ITS and 28S) markers for 55 accepted species in 23 of the extant genera, allow for six clades within Himerometroidea to be given family ranks. Maximum parsimony, maximum likelihood, and Bayesian inference analyses recovered largely congruent topologies with varying nodal support. A new classification revises generic placements among five families: Himerometridae, Colobometridae, and Mariametridae, all retained, and Pontiometridae and …

Photon Correlation Measurements And Second Harmonic Generation Using Pulsed Lasers, Apoorva Bisht

Physics Undergraduate Honors Theses

Correlation measurements are one of the fundamental ways to understand the photon statistics/distribution for a source of light. It is also an important method to confirm single photon sources by confirming the anitbunching nature. This project developed a correlation measurement system, utilized field programmable gate arrays, and non-linear crystals for processes like second harmonic generation and down conversion.

Subgroup Identification Via Interaction Tree And Mixed Model For Repeated Measures With Application To Alzheimer’S Disease, Zhichen Xu

Arts & Sciences Graduate Student Theses and Dissertations

No abstract provided.

An Integrated Experimental And Modeling Approach To Design Rotating Algae Biofilm Reactors (Rabrs) Via Optimizing Algae Biofilm Productivity, Nutrient Recovery, And Energy Efficiency, Gerald Benjamin Jones

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

Microalgae biofilms have been demonstrated to recover nutrients from wastewater and serve as biomass feedstock for bioproducts. However, there is a need to develop a platform to quantitatively describe microalgae biofilm production, which can provide guidance and insights for improving biomass areal productivity and nutrient uptake efficiency. This paper proposes a unified experimental and theoretical framework to investigate algae biofilm growth on a rotating algae biofilm reactor (RABR). The experimental laboratory setups are used to conduct controlled experiments on testing environmental and operational factors for RABRs. We propose a differential-integral equation-based mathematical model for microalgae biofilm cultivation guided by laboratory …

Detection Of Acetaminophen In Groundwater By Laccase-Based Amperometric Biosensors Using Mos2 Modified Carbon Paper Electrodes, Marcela Herrera-Domínguez, Koun Lim, Iris Aguilar-Hernández, Alejandra García-García, Shelley D. Minteer, Nancy Ornelas-Soto, Raúl Garcia-Morales

Chemistry Faculty Research & Creative Works

The use of enzyme-Based biosensors for the detection and quantification of analytes of interest such as contaminants of emerging concern, including over-the-counter medication, provides an attractive alternative compared to more established techniques. However, their direct application to real environmental matrices is still under investigation due to the various drawbacks in their implementation. Here, we report the development of bioelectrodes using laccase enzymes immobilized onto carbon paper electrodes modified with nanostructured molybdenum disulfide (MoS2). the laccase enzymes were two isoforms (LacI and LacII) produced and purified from the fungus Pycnoporus sanguineus CS43 that is native to Mexico. a commercial purified enzyme …

Building Community Resiliency Against Disasters, Zachary L. Doering

Undergraduate Honors Thesis Collection

Disasters impact people in many different places around the world. The impact to communities by disasters is shaped by their constructed vulnerability. The goal of this research project was to better understand how the vulnerability and resiliency of different communities was shaped at six different sites across the U.S. and to construct a collection of best practices to raise the resiliency of populations and locations in the face of many different forms of possible disasters in the future. These concepts and conclusions were drawn from internet research of the chosen sites. Phase 1 of the research determined noteworthy sites and …

Potential Control Of Invasive Mesquite Through Improving The Consumer’S Understanding Of Liquid Smoke Applications., Seth W. Ellsworth

Graduate Theses and Dissertations

Mesquite trees continue to invade forests and range lands in many countries across the world. The cost to remove these trees is staggering. In Texas, landowners spent $25 million over a 10- year period to clear 300,000 ha of mesquite trees, a fraction of the 22 million ha of Texas land affected by this invasion. Estimates are that the mesquite continues to negatively impact one to two percent of additional land in selected counties each year in Texas. However, the problem is not unique to Texas, but rather to the 44 species of mesquite trees, belonging to the genus Prosopis …

Brif: A Novel And Efficient Implementation Of Random Forests Based On Bit Packing And Parallel Computing, Yanchao Liu

Industrial and Systems Engineering Faculty Research Publications

Random forests are powerful and popular machine learning methods. While general principles of tree induction are straightforward and well-understood, the numerous algorithmic treatments implemented in software tools, as well as their impacts on performance, are less familiar to most users. This paper introduces a new random forest toolkit (the ‘brif’ package in R and Python) along with its key algorithmic design features, and demonstrates the effects of the forest’s hyper-parameters such as the split search method, tree depth and the voting mechanism, on the classification performance. Summaries of benchmarking experiments are also presented. Results show that ‘brif’ stands out among …

Using Immersive Technology To Improve Mechanical Design: Use Cases, A Review Of Current Technology, And An Experiment In Requirement Elicitation In Virtual Reality, William Hawthorne

All Theses

There has been a growing trend in the use of immersive technologies within engineering design. This research is focused on understanding how Virtual Reality (VR) technologies support design reviews. Modern tools including virtual reality hardware and software were tested for current capabilities and challenges. In a review of literature, two key gaps are identified: the rapid advancements of VR and AR technology and limited formal studies to determine the costs and benefits of immersive technology within engineering design reviews. This research has resulted in three key outcomes. First, use cases of immersive reality technologies are identified, through the lens of …

Analyzing Real Life Scenarios Through Linear And Exponential Functions Using Open Pedagogy., Lili Grigorian

Open Educational Resources

This assignment is on linear and exponential growth, which is connected to real life scenarios from students’ everyday life as well as teaches them financial responsibility and awareness of economic issues. Project has five parts. In part 1, students would use digital communication ability by creating a video about the topic from the knowledge they had prior to this project. In part 2 (the Mathematical part) they will use problem-solving and inquiry learning to better understand linear and exponential growth, in part 3 students will use global learning through reading to then annotate article and watch video to then discuss …

Theoretical And Computational Aspects Of Robust Cluster Analysis For Multivariate And High-Dimensional Datasets, Andrews Tawiah Anum

Open Access Theses & Dissertations

Multivariate and high-dimensional datasets typically contain subgroups that may not be immediately apparent. To reveal these groups, cluster analysis is performed. Cluster analysis is an unsupervised machine learning technique commonly employed to partition a dataset into distinct categories referred to as clusters. The k-means algorithm is a prominent distance-based clustering method. Despite overwhelming popularity, the algorithm is not invariant under non-singular affine transformations and is not robust, i.e., can be unduly influenced by outliers. To address these deficiencies, we propose an alternative model-based clustering procedure by minimizing a “trimmed” variant of the negative log-likelihood function. We develop a “concentration step”, …

Differentiating Biotic Vs. Abiotic Co2 In The Formation Of Pedogenic Carbonate In Agriculture And Natural Dryland Soils, Valeria Isabel Molina

Open Access Theses & Dissertations

Drylands, characterized by low and sporadic precipitation, require irrigation for crop growth. However, irrigation practices can lead to salt accumulation in soil due to high evaporation rates and reduced leaching. In addition to loading salts to soil, irrigation promotes the accumulation of secondary calcite. In natural systems, the formation of pedogenic carbonate (secondary calcite, CaCO3) is critical, impacting the soil properties hydrologically and biogeochemically, and modifying the global carbon cycle over geological time, albeit at a lower rate. In agricultural sites, irrigation water supplies HCO3- and Ca2+, accelerating the rates of CaCO3 formation and releasing abiotic CO2. This study investigated …

Incorporating Community Science In Improving Environmental Data Quality Through Model Based Reasoning Techniques, John Gilbert Olgin

Open Access Theses & Dissertations

This dissertation will address the questions: In what ways can MBR theory be applied to designtraining that will improve the capacity of Citizen scientists to collect and analyze high quality scientific data? To what degree does this training impact their ability to formulate complex understandings of environmental problems in their Citizen? The project will be comprised of three research objectives focused in three sections, carried out with NASAâ??s GLOBE Observer Citizen Science Program:

Section 1: An analysis of existing GLOBE data will be conducted, identifying whereerrors in data collection originate. At least three principal errors will be selected from this …

Modeling And Predicting Emerging Threats Using Disparate Data, Ismael Villanueva Miranda

Open Access Theses & Dissertations

Early detection is crucial to mitigate the impact of emerging threats. This work proposes four innovative frameworks that build machine learning and deterministic epidemiological models using multiple domain-specific datasets to detect the onset of emerging threats in two domains: infectious diseases and cybersecurity. Our models are designed to detect infectious disease outbreaks, model their spread, detect malware activity, and analyze the relationship between software/hardware weaknesses and attack techniques.

First, we present a novel framework to detect multiple infectious disease outbreaks by integrating standardized disease-specific domain knowledge and public search trend data. Our framework showed high performance in identifying infectious disease …

Novel Pathways To Tailor Charge And Spin In Materials And Investigating The Impact On Sensing And Electrochemical Energy Applications, Aruna Narayanan Nair

Open Access Theses & Dissertations

Catalysis is integral to our daily lives, as it streamlines and accelerates numerous chemical reactions essential for producing various materials, fuels, and chemicals. With the rising demand for clean, sustainable energy sources, optimizing catalytic materials and processes becomes increasingly vital. In the realm of renewable energy production, catalysis is crucial for efficiently converting energy from sustainable resources, such as solar, wind, and biomass, into chemical energy stored in fuels or directly into electrical energy.The electronic charge distribution in materials significantly influences their physical and chemical properties, facilitating the development of advanced electronic, optoelectronic, sensing, and energy conversion devices. Since catalysis …

Enhancing Basic Geology Skills With Artificial Intelligence: An Exploration Of Automated Reasoning In Field Geology, Perry Ivan Quinto Houser

Open Access Theses & Dissertations

This thesis explores the use of Artificial Intelligence, specifically semantics, ontologies, and reasoner techniques, to improve field geology mapping. The thesis focuses on two use cases: 1) identifying a geologic formation based on observed characteristics; and 2) predicting the geologic formation that might be expected next based upon known stratigraphic sequence. The results show that the ontology was able to correctly identify the geologic formation for the majority of rock descriptions, with higher search results for descriptions that provided more detail. Similarly, the units expected next were correctly given and if incorrect, would provide a flag to the field geologist …

Efficient Modelling Of Random Access Memory Cell: An Approach Using Qca Nanocomputing, Ali Newaz Bahar, Angshuman Khan

Turkish Journal of Electrical Engineering and Computer Sciences

Quantum-dot cellular automata (QCA) is innovative and potentially fruitful nanotechnology that provides a solution for transistor-based circuits with enhanced switching frequency, large-scale integration, and low power consumption. The random-access memory (RAM) cell is a fundamental component that is designed to operate quickly and effectively since memory is a core part of the semiconductor industry, thus the QCA family. The RAM cell design in this work is based on a multiplexer structure and is implemented without using coplanar crossovers of QCA technology. QCADesigner-2.0.3, a standard QCA layout design and verification tool, is used in the simulation and validation processes for the …

Catalytic Water Photolysis For Generating Renewable Hydrogen Fuel, Dr. Niveditha Nanda

Open Access Theses & Dissertations

Modern advances have enabled rapid industrialization and urbanization. However, the consequences of global modernization have included significant pollution to the air and water resources. Consequently, many changes to energy use must come to address and mitigate damages to our future. Solar energy derived hydrogen gas is a clean, renewable fuel that does not produce carbon dioxide or other pollutants. My research investigates the use of heterogeneous photocatalysis, by focusing on solar photochemical energy conversion, which is the making of hydrogen from water using sunlight. The production of clean, renewable hydrogen fuel will enable the utilization of low-cost, pollution-free energy resources …

Assessment Of Bridge Pier Response To Fire, Vehicle Impact, And Air Blast, Chen Fang, Qusai Alomari, Daniel G. Linzell

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Highway bridges exposed to intentional or unintentional fire followed by combined vehicle impact and air blast are at risk of significant damage and, possibly, collapse. Limited studies examining the complex effects of these extreme demands on bridge support elements and parametrizing their response and damage are found in the open literature. Research that is presented is part of an ongoing numerical investigation examining round, multi-column, reinforced concrete (RC), bridge pier behavior subject to multi-hazard scenarios involving fire, vehicle impact, and air blast. Detailed nonlinear finite element analysis models of single columns and multi-column piers supported by a pile foundation system …

Intrinsic Tame Filling Functions And Other Refinements Of Diameter Functions, Andrew Quaisley

Department of Mathematics: Dissertations, Theses, and Student Research

Tame filling functions are quasi-isometry invariants that are refinements of the diameter function of a group. Although tame filling functions were defined in part to provide a proper refinement of the diameter function, we show that every finite presentation of a group has an intrinsic tame filling function that is equivalent to its intrinsic diameter function. We then introduce some alternative filling functions—based on concepts similar to those used to define intrinsic tame filling functions—that are potential proper refinements of the intrinsic diameter function.

Adviser: Susan Hermiller and Mark Brittenham

Multiple Sequence Alignment Guided By Clam, Emily Light

Senior Honors Projects

For my honors project, I am continuing my research with my academic advisor, Dr. Daniels on creating an approach to the Multiple Sequence Alignment problem in the Rust programming language. This approach will be attached to Dr. Daniels’ CLAM (Clustered Learning for Approximate Manifolds) to enable it to globally and locally align DNA sequences. This research was divided into three separate parts: building the algorithms, implementing them into CLAM’s metric, and measuring and improving the performance of the algorithms. This project includes two separate but related algorithms; Needleman-Wunsch algorithm and the Smith-Waterman algorithm.

The Needleman-Wunsch algorithm takes in two DNA …

Modeling User Behavior For Cyber Security With Formal Methods And Agent Based Simulation, Hamdah Albalawi

Theses and Dissertations

Despite society’s positive outlook, technology poses real cyber security threats. Technology’s benefits can sometimes make it difficult to believe that potential threats lurk behind every device and platform. As cybercrime rises, we have come to rely increasingly on flawed devices and services. As cyberattacks become more prevalent, security professionals are committed to developing more robust and dependable security solutions. In cyber security, human error is regarded as the weakest link since all technical security solutions are vulnerable to human error. Among other human characteristics, risk-taking, logical decision-making, extraversion, and gender can significantly affect cyber security. However, there still is the …

Trace Dna Detection Using Diamond Dye: A Recovery Technique To Yield More Dna, Leah Davis

Master's Theses

This study aspires to find a new screening approach to trace DNA recovery techniques to yield a higher quantity of trace DNA from larger items of evidence. It takes the path of visualizing trace DNA on items of evidence with potential DNA so analysts can swab a more localized area rather than attempting to recover trace DNA through the general swabbing technique currently used for trace DNA recovery. The first and second parts consisted of observing trace DNA interaction with Diamond Dye on porous and non-porous surfaces.

The third part involved applying the Diamond Dye solution by spraying it onto …

Program And Proceedings: Nebraska Academy Of Sciences 1880–2023, 143rd Anniversary Year, One Hundred-Thirty-Third Annual Meeting, April 21, 2023

Nebraska Academy of Sciences: Programs and Proceedings

Program

Aeronautics and Space Science

Humans Past and Present

Applied Science and Technology Section

Biology

Biomedical Sciences

Chemistry

Earth Sciences

Environmental Science

Physics

Science Education

2023 Maiben Lecture: Jason Bartz

2023 Friend of Science Award: Ray Ward and Jim Lewis

Seasonal Variations In Nutrient And Total Suspended Solids Sources And Fluxes In Rivers Of Northern New Jersey And Newark Bay, Usa, Jing Nie

Theses, Dissertations and Culminating Projects

In recent decades, aquatic systems have experienced major problems with water quality due to high nutrient concentrations from both point and non-point sources resulting from industrialization, urbanization, and population growth. While nutrient pollution due to land use change cannot be ignored, point sources such as combined sewer overflows and discharging sites have also contributed to the problem. Integrated hydrodynamic, chemical, and biological models have been developed to simulate nutrient transportation from both sources. This paper reviews and analyzes water quality data from published literature to evaluate nutrient pollution in aquatic systems and emphasizes the need for a continuously developed integrated …