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Influence of Tools and Cutting Strategy on Milling Conditions and Quality of Horizontal Thin-Wall Structures of Titanium Alloy Ti6Al4V
Article describes how titanium and nickel alloys are used in the creation of components exposed to harsh and variable operating conditions. The authors state that a search is underway for cutting parameters that will minimize the vibration while meeting the quality requirements.
Date:
December 18, 2023
Creator:
Kurpiel, Szymon; Cudok, Bartosz; Zagórski, Krzysztof; Cieślik, Jacek; Skrzypkowski, Krzysztof & Brostow, Witold, 1934-
Object Type:
Article
System:
The UNT Digital Library
Development and Characterization of Compliant Bioelectronic Devices for Gastrointestinal Stimulation
In this research, we aimed to develop thin-film devices on a polymer substrate and an alternative 3D-printed device with macroelectrodes for treating gastrointestinal (GI) conditions. First, the fabrication of thin-film devices was demonstrated on a softening thiol-ene/acrylate polymer utilizing titanium nitride (TiN) as electrode material. This was achieved by utilizing cleanroom fabrication processes such as photolithography, wet and dry etching. The functionality of the device was shown by performing electrochemical characterization tests, mainly cyclic voltammetry, electrochemical impedance spectroscopy, and voltage transient. We synthesized a novel thiol-ene/acrylate polymer based on 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (TATATO), trimethylolpropanetris (3-mercaptopropionate) (TMTMP), and polyethylene glycol diacrylate (PEGDA). We show that this stretchable shape memory polymer substrate is well suited for cleanroom processes. Finally, for the high throughput of the wearable devices with electrodes size 10 mm in diameter, we implemented single electrode fabrication using printed circuit boards (PCBs) and depositing gold (Au) and TiN on the plated side of PCBs utilizing the sputtering tool. This step was followed by the assembly of those single electrodes on the flexible 3D printed device. We showed that the TiN electrode material performed better in terms of charge storage capacity and charge injection capacity than the widely used stainless steel electrode material …
Date:
December 2023
Creator:
Chitrakar, Chandani
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Factors Affecting MeHg Contamination of Spiders and Insect-Mediated MeHg Flux from Human-Made Ponds
The present study focused on methylmercury (MeHg) in emergent aquatic insects and spiders from human-made ponds. This dissertation addresses two main topics: (1) factors affecting variation in spider MeHg concentrations around human-made ponds and (2) the magnitude of MeHg transported out of human-made ponds by emergent aquatic insects (insect-mediated MeHg flux). Spiders were specifically targeted in this study because they have been proposed as sentinels of MeHg contamination (organism whose tissue concentrations reflect the level of MeHg in the environment). Spider MeHg concentrations were related to spider diet, size, and proximity to waterbody, but affected individual spider taxa differently. In a second study, I found that only "large" spiders within a taxa had tissue concentrations positively related to prey MeHg concentrations. These results indicate that the relationship between spider and prey MeHg could be size-dependent and that "large" spiders within a taxa may better reflect ambient MeHg contamination. Finally, I tested a conceptual model hypothesizing insect-mediated MeHg flux from human-made ponds is controlled by pond permanence and fish presence. In agreement with the conceptual model, insect-mediated MeHg flux from ponds was suppressed by the presence of fish, likely due to fish predation on emergent insect larvae. I found the mean …
Date:
December 2023
Creator:
Hannappel, Madeline Pratt
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Magnetoresponsive Layer-by-Layer (LBL) Polyelectrolyte Microcapsules Exposed to Low Frequency Alternating Magnetic Field for Drug Delivery to Breast Cancer Cells
Layer-by-layer (LBL) polyelectrolyte capsules can be modified to incorporate stimuli such as superparamagnetic nanoparticles which respond to a magnetic field only when it is turned on. Thus, they can act as a switch to load or unload their drug cargo on demand. Specifically, magnetite is incorporated into bilayer capsules made of alternating poly(allylamine hydrochloride) (PAH) and poly(sodium-p-styrenesulfonate) (PSS) which surrounds calcium carbonate core. The core is then dissolved using ethylenediaminetetraacetic acid (EDTA). These capsules are loaded with at FITC-BSA conjugate and examined with fluorescence to show the unloading of the FITC-BSA from capsules as it brightens the entire field of view of the microscope. The results suggest that we can next load and unload an anticancer drug such as doxorubicin using the combination of microcapsule and alternating magnetic field (AMF) to treat the cancer cells. Preliminary data interprets that the low frequency AMF we use has little to no adverse effect cells viability. This coincides with the general thought that low frequency AMF signals are not harmful to humans. Therefore, as an alternative to hyperthermia methods which use heat, it may be possible to deliver the anticancer drugs specifically to the cells when and where it is needed.
Date:
December 2023
Creator:
Powell, Robert Darrel
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Thermodynamics, Kinetics and Mechanical Behavior of Model Metallic Glasses
The thermophysical properties and deformation behavior of a systematic series of model metallic glasses was investigated. For Zr-based metallic glasses with all metallic constituents, the activation energy of glass transition was determined to be in the range of 74-173 kJ/mol while the activation energy of crystallization was in the range of 155-170 kJ/mol. The reduced glass transition temperature was roughly the same for all the alloys (~ 0.6) while the supercooled liquid region was in the range of 100-150 K, indicating varying degree of thermal stability. In contrast, the metal-metalloid systems (such as Ni-Pd-P-B) showed relatively higher activation energy of crystallization from short range ordering in the form of triagonal prism clusters with strongly bonded metal-metalloid atomic pairs. Deformation mechanisms of all the alloys were investigated by uniaxial compression tests, strain rate sensitivity (SRS) measurements, and detailed characterization of the fracture surface morphology. For the metal-metal systems, plasticity was found to be directly correlated with shear transformation zone (STZ) size, with systems of larger STZ size showing better plasticity. In metal-metalloid amorphous alloys, plasticity was limited by the distribution of STZ units, with lower activation energy leading to more STZ units and better plasticity. The alloys with relatively higher plasticity …
Date:
December 2023
Creator:
Akhtar, Mst Alpona
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
An Optimized Control System for the Independent Control of the Inputs of the Doherty Power Amplifier
Article describes how this study presents a systematic design of an optimized drive signal control system for 2.5 GHz Doherty power amplifiers (DPAs). In this manuscript, the authors analyzed and compared the PAE of the DPA and parallel-connected PA for diverse input signals generated using a designed optimized control system
Date:
November 14, 2023
Creator:
Sah, Pallav Kumar; Poulton, Matthew; Luyen, Hung & Mahbub, Ifana
Object Type:
Article
System:
The UNT Digital Library
Large-Scale Synthesis of Covalent Organic Frameworks: Challenges and Opportunities
Article describes how connecting organic building blocks by covalent bonds to design porous crystalline networks has led to covalent organic frameworks (COFs), consequently transferring the flexibility of dynamic linkages from discrete architectures to extended structures. Authors state that this review article highlights the fundamental of COFs, including designing principles, coupling reactions, topologies, structural diversity, synthetic strategies, characterization, growth mechanism, and activation aspects of COFs.
Date:
July 27, 2023
Creator:
Vardhan, Harsh; Rummer, Grace; Deng, Angela & Ma, Shengqian
Object Type:
Article
System:
The UNT Digital Library
Evaluation of the Vibration Signal during Milling Vertical Thin-Walled Structures from Aerospace Materials
Article describes how the main functions of thin-walled structures are to reduce the weight of the finished product and to increase the rigidity of the structure. The authors compared the vibration signal for different approaches to machining thin walled-components with vertical walls made of Ti6AI4V titanium alloy and Inconel 625 nickel alloy.
Date:
July 14, 2023
Creator:
Kurpiel, Szymon; Zagrórski, Krzysztof; Skryzpkowski, Krzysztof & Brostow, Witold, 1934-
Object Type:
Article
System:
The UNT Digital Library
Developmental Effects of a Non-Dioxin-Like Polychlorinated Biphenyl Mixture on Zebrafish (Danio rerio)
PCBs are synthetic organic compounds known for their toxicity to many organisms and are notorious for having large discrepancies between measured and nominal concentrations. Historically thought to be less toxic, non-dioxin-like (NDL) PCBs represent the majority of congeners and are capable of eliciting neurotoxic effects. NDL-PCBs remain understudied, including their effects on aquatic organisms. In the first study, I collected extensive chemistry data and data on neurobehavioral and cardiac endpoints to test the acute effects of exposure to an NDL-PCB mixture on early life stage zebrafish. Neurobehavioral effects observed in the first study indicated a potential for longer term behavioral effects in these fish. In the second study, I collected data on feeding, social, and memory behavior of zebrafish at time points beyond the acute exposure from the first study. Acute and longer-term behavioral endpoints in the first and second studies demonstrated effects from PCB exposure but did not indicate mechanisms. In the third study, I collected untargeted and targeted metabolomic data on amino acid, sugar, anionic compound, and neurotransmitter profiles to determine the specific pathways affected by exposure to an NDL-PCB mixture. These combined data from these studies provide a unique insight into the chemical profile of an NDL-PCB …
Date:
July 2023
Creator:
Green, Corey
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Experimental and Modeling Study of Water Time Histories during H2S-N2O Combustion in a Shock Tube
Article describes how, in the present study, the water formation was followed by laser absorption with N2O as an oxidant, instead of O2. Three H2S/N2O mixtures diluted in 98% Ar were studied to cover the following range of equivalence ratios: 0.5, 1.0, and 2.0, over a wide range of temperatures (1580–1940 K) around atmospheric pressure.
Date:
June 7, 2023
Creator:
Cooper, Sean P.; Marshall, Paul; Mathieu, Olivier; Pinzón, Laura T.; Mulvihill, Clayton R. & Glarborg, Peter
Object Type:
Article
System:
The UNT Digital Library
Collaborative Research: Research Infrastructure: CCRI: ENS: Enhanced Open Networked Airborne Computing Platform
Data management plan for the grant, "Collaborative Research: Research Infrastructure: CCRI: ENS: Enhanced Open Networked Airborne Computing Platform." The project aims to develop an enhanced open networked airborne computing platform to facilitate the design, implementation, and testing of an airborne computing platform that seamlessly integrates control, computing, communication, and networking. The project will provide community support based on the flywheel model, and to attract and engage community users through organized support from four regional sites in the nation, hands-on workshops, testbed access, and technical user services.
Date:
2023-05-15/2026-04-30
Creator:
Fu, Shengli
Object Type:
Text
System:
The UNT Digital Library
CEDAR: The Life and Music of Cedar Walton
Access:
Use of this item is restricted to the UNT Community
Grammy Award–winning pianist, bandleader, and composer Cedar Walton (1934–2013) is a major figure in jazz, associated with a variety of styles from bebop to funk and famous for composing several standards. Born and raised in Dallas, Walton studied music in Denver, where he jammed with musicians such as Charlie Parker and John Coltrane. In 1955, Walton moved to New York, immediately gaining recognition from notable musicians and nightclub proprietors. When Walton returned to the U.S. after serving abroad in the Army, he joined Benny Golson and Art Farmer’s Jazztet. Later, he became both pianist and arranger for Art Blakey’s Jazz Messengers. Next, he worked as part of Prestige Records’s house rhythm section, recording with numerous greats and releasing his own albums. One hallmark of Walton’s impact is his numerous long-term collaborations with giants such as trombonist Curtis Fuller and drummer Billy Higgins. By the end of his career, Walton’s discography, as both band member and bandleader, included many dozens of vaunted recordings with some of the most notable jazz musicians of the 1960s through the first decade of the twenty-first century. Ben Markley conducted more than seventy-five interviews with friends and family members, musicians who played with or were otherwise …
Date:
May 2023
Creator:
Ben Markley
Object Type:
Book
System:
The UNT Digital Library
Porous Organic Polymer-based Nanotraps for Metal Resource Recovery/Extraction from Water
The recovery processes of critical metals from multiple sources have turned more and more attention due to the increasing demand and consumption of them in modern industry. Many metals are used as significant components in manufacturing of a variety of products and equipment, playing significant roles in the economic security and national security; those metals involve rare earth elements (REEs), precious metals which include gold, silver, and platinum group metals (PGMs), and other valuable metals such as lithium, uranium, nickel, et al. The traditional approach to obtaining the above metals is by hardrock mining of natural ores via chemical and physical processes. However, this method of mining and refining metals from minerals is usually energy-consuming, costly, and environmental-destructive. Thus, various approaches to extracting or recycling target metals from the seawater or the solution of secondary resources as an alternative to traditional hardrock mining have been developed, and thereinto, using functional porous adsorbents to selectively capture specific metal ions from the aqueous resources has attracted increasing attention due to its outstanding merits such as high efficiency, energy-saving process, low cost, and reduced environmental impacts
Date:
May 2023
Creator:
Song, Yanpei
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
A Low-Power Wireless System for Predicting Early Signs of Sudden Cardiac Arrest Incorporating an Optimized CNN Model Implemented on NVIDIA Jetson
Article discusses the low survival rate of sudden cardiac arrest and its long-term risks that patients may experience. Authors propose a more effective method of recording and reporting sudden cardiac arrest symptoms so preventative measures may be instated earlier on to increase survival rate.
Date:
February 17, 2023
Creator:
Kota, Venkata Deepa; Sharma, Himanshu; Albert, Mark; Mahbub, Ifana; Mehta, Gayatri & Namuduri, Kamesh
Object Type:
Article
System:
The UNT Digital Library
Intelligent ECG Acquisition and Processing System for Improved Sudden Cardiac Arrest (SCA) Prediction
The survival rate for a suddent cardiac arrest (SCA) is incredibly low, with less than one in ten surviving; most SCAs occur outside of a hospital setting. There is a need to develop an effective and efficient system that can sense, communicate and remediate potential SCA situations on a near real-time basis. This research presents a novel Zeolite-PDMS-based optically unobtrusive flexible dry electrodes for biosignal acquisition from various subjects while at rest and in motion. Two zeolite crystals (4A and 13X) are used to fabricate the electrodes. Three different sizes and two different filler concentrations are compared to identify the better performing electrode suited for electrocardiogram (ECG) data acquisition. A low-power, low-noise amplifier with chopper modulation is designed and implemented using the standard 180nm CMOS process. A commercial off-the-shelf (COTS) based wireless system is designed for transmitting ECG signals. Further, this dissertation provides a framework for Machine Learning Classification algorithms on large, open-source Arrhythmia and SCA datasets. Supervised models with features as the input data and deep learning models with raw ECG as input are compared using different methods. The machine learning tool classifies the datasets within a few minutes, saving time and effort for the physicians. The experimental results …
Date:
December 2022
Creator:
Kota, Venkata Deepa
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Optical Control of Coherent Quantum Systems
Optical control of coherent quantum systems has many methods and applications. In this defense we will discuss the effects of an electric field interacting with molecules with dipole moments. The theoretical study of such molecules will consist of two-level atom and a three-level atom in the λ configuration. The methods that will be discussed are population trapping using both bright and dark starts obtained by both STIRAP and CHIRAP pulses. The application to be discussed is how to create a room temperature maser.
Date:
December 2022
Creator:
Roy, Colin Dean
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
An Optimized Control System for the Independent Control of the Inputs of Doherty Power Amplifier
This thesis presents an optimized drive signal control system for a 2.5 GHz Doherty power amplifier (PA). The designed system enables independent control of the amplitudes and phases of the drive signals fed to the inputs of two parallel PAs. This control system is demonstrated here for Doherty PA architecture with a combiner network which is used as an impedance inversion between the path of two parallel connected PAs. Independent control of the inputs is achieved by incorporating a variable attenuator (VA) and a variable phase shifter (VPS) in each of the two parallel paths. Integrating VA and VPS allows driving varying power levels with an arbitrary phase difference between the individual parallel PAs. A Combiner network consists of a quarter-wave transmission line at the output of the main power amplifier, which is used to invert the impedance between the main and peaking transistor. The specific VA (Qorvo QPC6614) and VPS (Qorvo QPC2108) components that are used for the test system provide an amplitude attenuation range from 0.5 dB to 31.5 dB with a step size of 0.5 dB and a phase range from 0◦ to 360◦ for a step size of 5.6◦at the intended operating frequency of 2.5 GHz, …
Date:
December 2022
Creator:
Sah, Pallav Kumar
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Three-Dimensional Printed, Dual-Band, Dual-Circularly Polarized Antenna Array Using Gap Waveguide Technology
Article proposes a gap waveguide (GW)-based 4 × 4 dual-band, dual-circularly polarized antenna array. The combination of dual-band, dual-circularly polarized capability, high gain, high efficiency, lightweight, low cost and compact size renders the proposed design a potential candidate for commercial millimeter wave communication applications.
Date:
October 22, 2022
Creator:
Wu, Sifan; Li, Jianxing; Cao, Yuanxi; Yan, Sen; Xu, Kaida & Luyen, Hung
Object Type:
Article
System:
The UNT Digital Library
A Parallel Convolution and Decision Fusion-Based Flower Classification Method
This article proposes a novel flower classification method that combines enhanced VGG16 (E-VGG16) with decision fusion.
Date:
August 4, 2022
Creator:
Jia, Lianyin; Zhai, Hongsong; Yuan, Xiaohui; Jiang, Ying & Ding, Jiaman
Object Type:
Article
System:
The UNT Digital Library
Acute Toxicity of Crude Oil Exposures to Early Life Stage Teleosts: Contribution of Impaired Renal Function and Select Environmental Factors
Oil spills are well-known adverse anthropogenic events, as they can induce severe impacts on the environment and negative economic consequences. Still, much remains to be learned regarding the effects of crude oil exposure to aquatic organisms. The objectives of this dissertation were to fill some of those knowledge gaps by examining the effects of Deepwater Horizon (DWH) crude oil exposure on teleost kidney development and function. To this end, I analyzed how these effects translate into potential osmoregulatory impairments and investigated the interactive effects of ubiquitous natural factors, such as dissolved organic carbon (DOC) and ultraviolet (UV) light, on acute crude oil toxicity. Results demonstrated that acute early life stage (ELS) crude oil exposure induces developmental defects to the primordial kidney in teleost fish (i.e., the pronephros) as evident by alterations in: (1) transcriptional responses of key genes involved in pronephros development and function and (2) alterations in pronephros morphology. Crude oil-exposed zebrafish (Danio rerio) larvae presented defective pronephric function characterized by reduced renal clearance capacity and altered filtration selectivity, factors that likely contributed to the formation of edema. Latent osmoregulatory implications of crude oil exposure during ELS were observed in red drum (Sciaenops ocellatus) larvae, which manifested reduced survival …
Date:
August 2022
Creator:
Bonatesta, Fabrizio
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Chemically Optimized Cu Etch Bath Systems for High-Density Interconnects and the FTIR Operando Exploration of the Nitrogen Reduction Reaction on a Vanadium Oxynitride Electrocatalyst
Printed circuit board manufacturing involves subtractive copper (Cu) etching where fine features are developed with a specific spatial resolution and etch profile of the Cu interconnects. A UV-Vis ATR metrology, to characterize the chemical transitions, has been developed to monitor the state of the bath by an in-situ measurement. This method provides a direct correlation of the Cu etch bath and was able to predict a 35% lower etch rate that was not predicted by the three current monitoring methods (ORP, specific gravity, and conductivity). Application of this UV-Vis ATR probe confirmed that two industrial etch baths, in identical working conditions, confirmed a difference in Cu2+ concentration by the difference of the near IR 860nm peak. The scope of this probe allowed chemically specific monitoring of the Cu etch bath to achieve a successful regeneration for repeated use. Interlayer dielectrics (ILDs) provide mechanical and electrical stability to the 3D electrical interconnects found in IC devices. It is particularly important that the structural support is created properly in the multilayered architecture to prevent the electrical cross signaling in short range distances. A combined multiple internal reflection and transmission FTIR has been employed for the characterization of silicon oxycarbonitride (SiOCN) films. These …
Date:
August 2022
Creator:
Caperton, Joshua M
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Common Strategies for Regulating Emotions across the Hierarchical Taxonomy of Psychopathology (HiTOP) Model
The hierarchical taxonomy of psychopathology (HiTOP) is a novel classification system that adopts both a dimensional and hierarchical approach to psychopathology to address shortcomings. However, the HiTOP framework is descriptive in nature and requires additional research to consider potential mechanisms for the onset and maintenance of psychopathology, such as cognitive-behavioral emotion regulation strategies. To redress this gap, a sample of 341 adults who endorsed ongoing mental health concerns completed self-report measures of emotion regulation strategies and psychopathology. The data revealed a three-spectra HiTOP model consisting of internalizing, thought disorder, and antagonistic externalizing. Results found that psychopathology was most strongly associated with avoidance, catastrophizing, expressive suppression, and self-blame. In contrast, adaptive strategies were generally unrelated to the HiTOP spectra. This pattern was strongest for internalizing, distress, and detachment. Fewer, yet noteworthy unique relationships between the strategies and specific spectra/subfactors were also found. These findings suggest that psychopathology may be best conceptualized as an overutilization of maladaptive emotion regulation strategies. Furthermore, the results indicate there is added benefit to considering these strategies within a hierarchical approach to psychopathology. These associations alert clinicians to potential treatment targets and contribute to an ongoing literature that seeks to identify underlying mechanisms of the structure of …
Date:
August 2022
Creator:
Bennett, Charles B.
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library
Texas Register, Volume 47, Number 25, Pages 3587-3762, June 24, 2022
A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date:
June 24, 2022
Creator:
Texas. Secretary of State.
Object Type:
Journal/Magazine/Newsletter
System:
The Portal to Texas History
Design of a Low-Cost Spirometer to Detect COPD and Asthma for Remote Health Monitoring
This work develops a simple and low-cost microphone-based spirometer with a scalable infrastructure that can be used to monitor COPD and Asthma symptoms. The data acquired from the system is archived in the cloud for further procuring and reporting. To develop this system, we utilize an off-the-shelf ESP32 development board, MEMS microphone, oxygen mask, and 3D printable mounting tube to keep the costs low. The system utilizes the MEMS microphone to measure the audio signal of a user's exhalation, calculates diagnostic estimations and uploads the estimations to the cloud to be remotely monitored. Our results show a practical system that can identify COPD and Asthma symptoms and report the data to both the patient and the physician. The system developed can provide a means of gathering respiratory data to better assist doctors and assess patients to provide remote care.
Date:
May 2022
Creator:
Olvera, Alejandro
Object Type:
Thesis or Dissertation
System:
The UNT Digital Library