Digital Commons Network^™

Computational And Experimental Study On Undoped And Er-Doped Lithium Tantalate Nanofluorescent Probes, Mkhitar A. Hobosyan, Andrea Pelayo Carvajal, Bhupendra B. Srivastava, Tamanna Zakia, Mohammed Uddin, Karen S. Martirosyan, Eric Rodriguez, Kofi Nketia Ackaah-Gyasi, Nicholas Dimakis

Physics & Astronomy Faculty Publications

We present a combined density functional theory (DFT) and experimental work on lithium tantalate LiTaO3 (LT) and its Er-doped counterparts. We calculate the electronic and optical properties for both LT and LT:Er+3, with Er occupying either Li or Ta sites, at 4.167 mol%. The generalized gradient approximation (GGA) calculations show that the Er-4 f bands appear closer to the conduction band bottom and to the valance band top, for the first and second doped configurations, respectively. This agrees with changes in the imaginary part of the frequency dependent dielectric function between the doped configurations. There are striking differences between the …

Laser-Induced Forward Transfer (Lift) Based Bioprinting Of The Collagen I With Retina Photoreceptor Cells, Md Shakil Arman, Ben Xu, Andrew Tsin, Jianzhi Li

Manufacturing & Industrial Engineering Faculty Publications

This study focuses on the 3D bioprinting of retina photoreceptor cells using a laser-induced forward transfer (LIFT) based bioprinting system. Bioprinting has a great potential to mimic and regenerate the human organoid system, and the LIFT technique has emerged as an efficient method for high-resolution micropatterning and microfabrication of biomaterials and cells due to its capability of creating precise, controlled microdroplets. In this study, the parameters for an effective femtosecond laser-based LIFT process for 3D bioprinting of collagen biomaterial were studied. Different concentrations of collagen I solutions were tested and 0.75 mg/ml to 1 mg/ml collagen Ⅰ was identified as …

Assessing The Effects Of A Mixed Eimeria Spp. Challenge On Performance, Intestinal Integrity, And The Gut Microbiome Of Broiler Chickens, Danielle Graham, Victor Petrone-Garcia, Xochitl Hernandez-Velasco, Makenly E. Coles, Marco A. Juarez-Estrada, Juan D. Latorre, Jianmin Chai, Stephanie Shouse, Jiangchao Zhao, Aaron Forga, Roberto Señas-Cuesta, Lauren Laverty, Kristen Martin, Carolina Trujillo-Peralta, Ileana Loeza, Latasha Gray, Billy M. Hargis, Guillermo Tellez-Isaias

Poultry Science Faculty Publications and Presentations

A mixed Eimeria spp. challenge model was designed to assess the effects of challenge on broiler chicken performance, intestinal integrity, and the gut microbiome for future use to evaluate alternative strategies for controlling coccidiosis in broiler chickens. The experimental design involved broiler chickens divided into two groups: a control group (uninfected) and a positive control group, infected with Eimeria acervulina (EA), Eimeria maxima (EM), and Eimeria tenella (ET). At day-of-hatch, 240 off-sex male broiler chicks were randomized and allocated to one of two treatment groups. The treatment groups included: (1) Non-challenged (NC, n = 5 replicate pens); and (2) challenged …

Cooperative Activation Of Pdk1 And Akt By Mapk4 Enhances Cancer Growth And Resistance To Therapy, Tao Shen, Xiangsheng Huang, Ping Yi, Bingning Dong, Feng Yang

Faculty, Staff and Students Publications

Phosphoinositide-dependent kinase-1 (PDK1) is a master kinase of the protein A, G, and C (AGC) family kinases that play important roles in regulating cancer cell proliferation, survival, and metabolism. Besides phosphorylating/activating AKT at the cell membrane in a PI3K-dependent manner, PDK1 also exhibits constitutive activity on many other AGC kinases for tumor-promoting activity. In the latter case, PDK1 protein levels dominate its activity. We previously reported that MAPK4, an atypical MAPK, can PI3K-independently promote AKT activation and tumor growth. Here, using triple-negative breast cancer (TNBC) cell models, we demonstrate that MAPK4 can also enhance PDK1 protein synthesis, thus phosphorylate/activate PDK1 …

Survey Of How Irregularities In The Electrical System Of The Human Heart Link To Different Heart Arrhythmias, Jazmine Boloor

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis explores the circuital pathway that a signal takes within the heart throughout a full heartbeat and provides a timing analysis. It then surveys the different pathways that could arise in the electrical system of the heart, and the associated heart diseases linked to the location of each pathway. Common heart arrhythmias such as atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia, atrial flutter, and atrial fibrillation are surveyed, and their pathways are analyzed. Electrocardiograms are presented to aid in understanding of the timing analysis associated with irregularity in heart function. Finally, this thesis explores an avenue of the heartbeat …

Instructional Practices That Foster Argumentative Discourse In Secondary Science Classrooms, Alicia N. Herrera

UNLV Theses, Dissertations, Professional Papers, and Capstones

To remain competitive in an innovative world, American classrooms are promoting careers in science, technology, engineering, and mathematics (STEM) by utilizing the Next Generation Science Standards (NGSS). Students are engaged in inquiry by applying scientific practices like argumentation. However, science teachers are finding it difficult to respond to, as well as deepen students’ argumentative conversations. Therefore, research must uncover what instructional practices (or combinations) are used to overcome classroom obstacles, along with fostering students’ discourse and sensemaking. A teacher research approach was taken to investigate how the researcher, a secondary science teacher herself, effectively combines three under-researched instructional practices for …

Development Of Pre-Magnetized Magnetorheological Elastomer For Bidirectionally Variable Stiffness Applications, Choonghan Lee

UNLV Theses, Dissertations, Professional Papers, and Capstones

Magnetorheological elastomers (MREs) utilize magnetic forces between ferromagnetic particles to cause variable stiffness properties and damping with external magnetic fields. In the MREs, the particles are embedded in a cured elastomer matrix, and an external magnetic field makes the stiffness change due to induced magnetic forces among particles. A disadvantage of the conventional MREs is that they cannot be softened (reduced stiffness) under an external magnetic field. Considering that there are many engineering applications where fast changes of stiffness in both directions (stiffening and softening) are required, embedding magnetically biased particles in the MRE can provide potential solutions. In this …

An Avalanche Transistor-Based Pulse Generator Design For Infrared Laser Applications, Abraham Lopez

UNLV Theses, Dissertations, Professional Papers, and Capstones

This thesis details the design and results of a circuit intended for infrared laser applications, specifically for transcranial infrared light simulation (TILS) experiments and for use as a range finder. The circuit itself is comprised of a transistor, high voltage power supply, laser diode, capacitor, resistor, diode, and low voltage pulse. The design of a range finder is also developed. The range finder design is the same as the circuit developed for TILs with the addition of a few more components for receiving the returned light pulse such as a photodiode, op-amp, and comparator. The techniques used for a successful …

Development And Characterization Of Lead & Lead-Free Perovskite Solar Cell Materials, Rubaiya Murshed

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, perovskite photovoltaic technology has offered enormous viability and dimensionality in solar cell research. As a light-harvesting active layer, Perovskite generated remarkable development in device efficiency of 25.7% for the single-junction solar cell, and over 33% for the perovskite/silicon tandem solar cell. Also, perovskite-perovskite tandem solar cell (also called all-perovskite tandem solar cell) shows great potential in device performance and achieved a power conversion efficiency (PCE) of 26.4%. Transitioning photovoltaic technology from the laboratory to commercial products, high PCE, low cost, long lifetime, and low toxicity are some of the critical factors to consider during material selection. Pb-halide …

Facial Expression Recognition Using Convolutional Neural Networks (Cnns) And Generative Adversarial Networks (Gans) For Data Augmentation And Image Generation, Shekhar Singh

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facial expressions play a crucial role in human communication, serving as a powerful means to convey emotions. However, classifying facial expressions using artificial intelligence (AI) can be challenging, especially with small datasets and images. Facial Expression Recognition (FER) is an active area of research, with Convolutional Neural Networks (CNNs) being widely employed for classification. In this research, we propose a CNN-based approach for FER that utilizes both original and augmented datasets to enhance classification accuracy. Experimental results on the FER2013 dataset show test accuracies of 63.39% and 64.59% for the original and augmented datasets, respectively, in a seven-class classification task. …

Towards Cfd Investigations Into Particulate Air Pollution Of A Desert Urban Environment, Prosun Roy

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation has explored computational fluid dynamics (CFD) techniques for studying particulate air quality in the Las Vegas urban area. The dissertation is based on three research tasks:

• • High time-resolution fenceline air quality sensing and dispersion modeling for environmental justice-centered source attribution. (Chapter 2)
• • Pollen dispersion and deposition in real-world urban settings: A computational fluid dynamic study. (Chapter 3)
• • Effects of urban canopy parameterizations on modeling pollen dispersion and exposure. (Chapter 4)

In Chapter 2, we investigate the facilitation of low-cost air quality sensors (LCAQS) and CFD technique on exposure assessment of environmental justice (EJ) communities and …

Lunchbox Hydroponics, Stacy A. Adams

Department of Agronomy and Horticulture: Faculty Publications

Growing plants with hydroponics is less complicated than it may appear when the fundamentals of the system are understood. This publication provides instruction on the construction of a simple hydroponic prototype suitable for school or youth education programs. The fundamentals of hydroponics, basic design of a solution system, seed starting, creating a nutrient solution, and plant care are explored through this engaging project. This prototype can successfully be used to grow small edible and herb plants in the classroom or at home.

Leveraging Eco-Evolutionary Models For Gene Drive Risk Assessment, Matthew A. Combs, Andrew J. Golnar, Justin M. Overcash, Alun L. Lloyd, Keith R. Hayes, David A. O'Brochta, Kim M. Pepin

United States Department of Agriculture Wildlife Services: Staff Publications

Engineered gene drives create potential for both widespread benefits and irreversible harms to ecosystems. CRISPR-based systems of allelic conversion have rapidly accelerated gene drive research across diverse taxa, putting field trials and their necessary risk assessments on the horizon. Dynamic processbased models provide flexible quantitative platforms to predict gene drive outcomes in the context of system-specific ecological and evolutionary features. Here, we synthesize gene drive dynamic modeling studies to highlight research trends, knowledge gaps, and emergent principles, organized around their genetic, demographic, spatial, environmental, and implementation features. We identify the phenomena that most significantly influence model predictions, discuss limitations of …

Integrating Sensor Development, Risk Assessment, And Community Engagement To Support Environmental Justice In The Rural Community Of El Tiple, Colombia, David Bahamon Pinzon

All Dissertations

In Colombia, ethnic communities have traditionally been responsible stewards of natural resources. They recognize the importance of these resources for their livelihood, as well as their ancestral and cultural heritage. El Tiple, a rural Afro-Colombian community, has been affected by the incursion of private corporations that promoted the expansion of sugarcane monocrops in their territory. Since the introduction of the monoculture industry, local freshwater sources have been depleted due to intensive water use for irrigation of the sugarcane crops. Additionally, the intensive usage of agrochemicals has been linked with loss of native flora, damages to family farms, and pollution of …

Apheresis Collection Of Mononuclear Cells For Chimeric-Antigen Receptor Therapies, Robert W. Maitta

Faculty Scholarship

Collections of lymphocytes to be genetically modified to treat hematologic malignancies have seen a dramatic increase over the last few years as commercial products have been approved. Reports of new products in development that can possibly treat solid organ malignancies represent a massive change in the field. Apheresis is at the center of the collection of cells for the manufacture of these chimeric-antigen receptor therapy products. The expansion of these collections represents one of the areas of apheresis procedures growth. This review will summarize concepts important to this type of collection and variables that need to be optimized to obtain …

Columns Fall 2023, Southern Adventist University

Alumni Newsletter

Features information about Southern Adventist University's archeological museum, enrollment growth, Homecoming, and the annual Alumni Association Tour.

Distinct Modes Of Aged Soil Carbon Export In A Large Tropical Lake Basin Identified Using Bulk And Compound-Specific Radiocarbon Analyses Of Fluvial And Lacustrine Sediment, Wesley G. Parker, Jason M.E. Ahad, Jonathan Obrist-Farner, Benjamin Keenan, Peter M.J. Douglas

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The 14C content of sedimentary organic matter (OM) and specific organic molecules provide valuable information on the source and age of OM stored in sediments, but these data are limited for tropical fluvial and lake sediments. We analyzed 14C in bulk OM, palmitic acid (C16), and long-chain n-alkanoic acids (C24, C26, and C28), within fluvial and lake sediments in the catchment of Lake Izabal, a large tectonic lake basin in Guatemala. We combined these measurements with bulk and compound-specific δ13C measurements, as well as sediment organic carbon to nitrogen (OC:N) ratios, to understand the source and age of sedimentary OM …

Thermophysical Properties Of Additively Manufactured (Am) Grcop-42 And Grcop-84, Yehong Chen, Congyuan Zeng, Huan Ding, Selami Emanet, Paul R. Gradl, David L. Ellis, Shengmin Guo

Faculty Publications

Additive manufacturing (AM) has enabled new opportunities of high-performance alloys for use in complex components across the aerospace, industrial, automotive, and energy industries. These industries have growing interest in copper alloys and AM for high-performance heat exchangers such as rocket engine combustion chambers. GRCop copper alloys, such as GRCop-84 (Cu-8Cr-4 Nb at%) and GRCop-42 (Cu-4Cr-2 Nb at%), have high thermal conductivity and high mechanical properties at elevated operating temperatures. In this paper, thermophysical properties for GRCop-84 and GRCop-42 produced using laser powder bed fusion (L-PBF) are examined. While L-PBF parameters and resulting microstructures can be achieved in a laboratory environment, …

Form Auto Generation: An Analysis Of Gui Generation, Jedadiah Mcfarland

Theses/Capstones/Creative Projects

Graphical User Interfaces (GUIs) have transformed how we interact with computers, offering visually appealing and intuitive systems. This paper explores the origins and evolution of GUIs, explicitly focusing on form auto-generation in modern GUI-driven environments. Form auto-generation has emerged as a prominent practice, enabling automatic form creation based on predefined models. To better understand form auto-generation, I investigate SurveyJS, an open-source form auto-generation library known for its active development and support. This investigation aims to understand how SurveyJS recognizes and renders objects from a JSON model. The methodology involves a trial and error examination of the library, exploring its live …

A Conceptual Investigation Of Transition To Self-Driven Turbidity Currents From Along-Shelf Current-Supported Turbidity Currents, Celalettin E. Ozdemir, Liangyi Yue, Haq Murad Nazari, George Xue, Samuel J. Bentley, Shuo Yang, Sayed O. Hofioni, Robert Forney, Saber Aradpour

Faculty Publications

Wave- and current-supported turbidity currents (WCSTCs) are one of the sediment delivery mechanisms from the inner shelf to the shelf break. Therefore, they play a significant role in the global cycles of geo-chemically important particulate matter. Recent observations suggest that WCSTCs can transform into self-driven turbidity currents close to the continental margin. However, little is known regarding the critical conditions that grow self-driven turbidity currents out of WCSTCs. This is in part due to the knowledge gaps in the dynamics of WCSTCs regarding the role of density stratification. Especially the effect of sediment entrainment on the amount of sediment suspension …

A Robust Experimental Design For Conceptual Model Discrimination Based On Information Theory, Hai V. Pham, Frank T.C. Tsai

Faculty Publications

This study introduces firm information gain for model discrimination based on Shannon entropy and worst-case scenario experimental design. Firm information gain is the minimal additional information gained by an experimental design with respect to existing information. Robust experimental design aims to maximize the firm information gain by searching for the least number of new pumping wells and observation wells. Robust experimental design includes a Bayes factor threshold to ensure that new data provide strong evidence for model discrimination. To maximize the firm information gain, a framework is proposed that combines the parallel-sequential genetic algorithm (GA) for parallel computing and the …

Performance Optimization Study Of The Neuromorphic Radiation Anomaly Detector, James Ghawaly, Aaron Young, Andrew Nicholson, Brett Witherspoon, Nick Prins, Mathew Swinney, Cihangir Celik, Catherine Schuman, Karan Patel

Faculty Publications

This work reports on new results and insights from the optimization of spiking neural networks developed for gamma-ray radiation anomaly detection. Our previous paper introduced the first known neuromorphic algorithm for this application, demonstrating promising results and insights into optimal hyperparameter selection - particularly in the choice of data input encodings. Since the first paper, we have tested the algorithms on new datasets to investigate transferability from one background radiation environment to another. We have also performed a new hyperparameter optimization experiment with this new dataset to investigate the impact of new radiation data formatting techniques, the inclusion or neuronal …

Dynamic Response Of Cohesive-Frictional Soils Under Thermo-Controlled Constant Water Content Cyclic Simple Shear Testing, Daniel Robert Green

Civil Engineering Dissertations - Archive

Dynamic Response of Cohesive-Frictional Soils Under Thermo-Controlled Constant Water Content Cyclic Simple Shear Testing Daniel R. C. Green The University of Texas at Arlington, 2023 Supervising Professor: Dr. Laureano R. Hoyos A considerable portion of the emerging geothermal infrastructure in the country is located in earthquake prone areas while being supported and/or surrounded by soil deposits located well above the groundwater table. Geotechnical earthquake research in the country, however, continues to be mostly focused on soil response under saturated conditions, especially soil liquefaction phenomena, while most of the work on dynamic response of compacted soils has not taken thermal conditioning …

Cement-Based Nanocomposites With Tunable Electrical And Thermal Conductivity, Myrsini Maglogianni

Civil Engineering Dissertations - Archive

ABSTRACT: While concrete, the most widely used construction material exhibits low electrical and thermal conductivity, it can be engineered at the nanoscale to exhibit energy-related functionalities. This dissertation aims to develop nanoengineered cementitious composites with high electrical conductivity and tunable thermal conductivity to enable energy-related functionalities such as electricity generation and thermal heating capabilities. Highly dispersed nanostructured materials with different intrinsic properties were used to modify the thermal and electrical properties of the developed cementitious composites to enable their thermoelectric (TE) and/or electrothermal (ET) characteristics. One of the objectives of this research was to optimize the electrical-to-thermal energy conversion capability …

Investigation On The Impacts Of Land Subsidence And Urbanization On Flood Inundation In Texas, Han Jiang

Civil Engineering Dissertations - Archive

Floods, being a prevalent and catastrophic natural hazard, have resulted in enormous losses to human lives and properties all over the world. Hence, there is a pressing need to enhance urban resilience and to improve emergency response capacities in order to mitigate the risks posed by flood hazards. Many models have been developed by engineers to simulate and examine the hydrologic and hydraulic responses to the changes within the physical environment. However, there are still knowledge gaps in advancing the understanding of the H&H behavior and hydrodynamics modeling performance. This doctoral study aims to help bridge such gaps via assessing …

An Integrated Algorithm For Automatic Gpr Data Processing For Concrete Rebar Location, Lihong Mao

Civil Engineering Dissertations - Archive

ABSTRACT: Ground Penetrating Radar (GPR) has emerged as a valuable nondestructive testing technique for subsurface imaging and characterization in civil engineering applications. In particular, GPR plays a crucial role in the evaluation of reinforced concrete (RC) structures, enabling the determination of concrete cover thickness and the localization of reinforcement. However, the effectiveness of GPR data analysis is often hindered by inherent challenges, such as unknown time-zero, strong noise, and blurred signals, making the accurate and simultaneous determination of rebar horizontal location and depth a challenging task. This Ph.D. research aims to address these challenges and enhance the accuracy and efficiency …

Digital Twin Enabled Winter Operations Management Through The Integration Of Artificial Intelligence, Sensory Level Data, And Publicly Available Data, Pooya Darghiasi

Civil Engineering Dissertations - Archive

Monitoring real-time information on road conditions, especially during winter storms, is crucial to establishing winter maintenance strategies by the State Departments of Transportation (State DOTs) in the United States. States and local highway agencies allocate substantial resources each year for winter operations to improve road safety during winter storms. However, most weather-related vehicle accidents happen on snowy, slushy, or icy surfaces, leading to a significant number of fatalities and injuries annually. Traditionally, transportation agencies rely on the information provided by Road Weather Information Systems for monitoring road conditions along roadways. However, these systems are costly and only provide estimates at …

Towards Sustainable Additive Manufacturing: Assessment Of Cost, Greenhouse Gas Emission, And Recyclability, Lei Di

Industrial, Manufacturing, and Systems Engineering Dissertations - Archive

Additive Manufacturing technologies fabricate 3D objects layer by layer following a predesigned CAD model. Owing to the unique layer-wise production method, additive manufacturing offers competitive advantages in comparison with traditional subtractive manufacturing, such as shortened production time, increased design freedom, improved manufacturing capability and complexity, and reduced manufacturing waste. Numerous research studies have been conducted to design, understand, and improve additive manufacturing technologies in order to facilitate the implementation in the supply chain. On the other hand, with the rapid growth of additive manufacturing, sustainability issues that exist on both process level and supply chain level have started to receive …

Large Eddy Simulation By Using Wang’S Liutex-Based Subgrid Model, Vishwa Shah

Mathematics Dissertations - Archive

Turbulent flows and vortex structures in fluid dynamics have been captivating researchers for decades, owing to their intrinsic complexity and significance in various industrial and natural processes. Despite their fundamental importance, the definition and identification of vortices in turbulent flows continue to pose challenges, and to date, no universally accepted approach exists. This pursuit dates to the pioneering work of Hermann von Helmholtz in the 19th century, when the concept of vortices was first introduced. In 2019, Liu et al. introduced a novel physical quantity termed "Liutex" in scalar, vector, and tensor forms, providing a promising avenue for understanding and …

Development & Validation Of Needle-Based Metrics For Hemodialysis Cannulation Skill Assessment, Ziyang Zhang

All Dissertations

Dialysis is a vital medical treatment for patients with end-stage renal disease. An arteriovenous fistula, a surgically created connection between an artery and a vein, is the preferred vascular access for dialysis due to superior clinical outcomes. However, cannulation complications caused by needle-related errors are common and dangerous, necessitating the need for effective cannulation training. Despite cannulation being a challenging and complex clinical procedure, little is known about the quantitative aspects of needle insertion dynamics necessary for skilled cannulation. The aim of this study was to develop meaningful and instructive needle-based metrics for cannulation skill assessment and training.

Two iterations …