PHD, Kent State University, 2024, College of Arts and Sciences / School of Biomedical Sciences

Wound healing is a very complex process requiring a well-orchestrated integration of multiple cellular and molecular events involving many players for antimicrobial activity and the promotion of new vascular formation. Acute wounds are healed by following the normal process of repair including inflammation, proliferation, and remodeling phases. If acute wounds fail to progress through the normal healing phases, it can develop into delayed healing or non-healing chronic wounds, particularly associated with the presence of bacterial biofilm (a community of bacteria encased in a protective matrix) and impaired angiogenesis. Conventional antibiotics frequently develop resistance and have limited efficacy against biofilm-associated wound infections. Approaches for promoting pro-angiogenic activity for wound healing have been relied on the use of bioactive molecules or growth factors, which have limitations in developing cost-effective treatment options. Additionally, thus far, each of the above aspects for antimicrobial and proangiogenic activities have been separately investigated to a great extent and an integrated approach to simultaneously addressing these three issues in a single drug delivery platform has yet to emerge. Wound scaffolds are biomaterial platforms designed to support tissue regeneration and enhance wound healing. In particular, nanoparticle-based scaffolds hold promise for treating chronic wounds due to their characteristics to exhibit higher reactivity due to high surface to volume ratio for improved cellular interactions, and easiness in surface functionalization, and controlled release of bioactive molecules. Additionally, their small size enables deep penetration into the wound bed. In this study, we propose to harness the unique characteristic of copper ion that can exhibit antibacterial and pro-angiogenic properties towards developing a cost-effective 33 scaffold for treating chronic wounds. Copper has emerged as an essenti (open full item for complete abstract)

Doctor of Philosophy, Case Western Reserve University, 2024, Biomedical Engineering

Cancer therapy has significantly advanced over the past few decades due to development of improved surgical technique, early detection, and novel therapy development. However, cancer remains one of the most lethal diseases due to metastasis, drug resistance, and recurrence. Immunotherapy holds the promise of utilizing the body's immune system to eliminate cancer cells. Immune checkpoint blockade therapy remains the most common utilization of immunotherapy in the clinical but yields varying degrees of success due to the massively immunosuppressed tumor microenvironment. Discovery of novel immune checkpoints and technology for targeting these checkpoints is critical for the advancement of cancer immunotherapy. The novel immune checkpoint protein VISTA (V-domain Immunoglobulin Suppressor of T cell Activation) impairs the toll-like receptor (TLR)-mediated activation of myeloid antigen presenting cells, promoting the expansion of myeloid derived suppressor cells, and suppressing tumor-reactive cytotoxic T cell function. Gene therapy targeting the VISTA checkpoint protein in conjunction with potent TLR agonists represents a safer yet potent alternative to antibody mediated cancer immunotherapy that has shown toxicity in the clinic. The overall objective of the work in this dissertation is to develop nanoparticle platforms for delivery of gene therapy mediate immune checkpoint blockade cancer immunotherapy regiments. First, a dual action lipid nanoparticle (Dual-LNP) that incorporates a VISTA-specific siRNA and a TLR9 agonist (unmethylated CPG) is developed. The Dual-LNP ensures co-delivery of both cargoes to tumor-infiltrating myeloid cells, leading to simultaneous silencing of VISTA and stimulation of TLR9. Next, the efficacy of the Dual-LNP was tested in multiple solid tumor models. The Dual-LNP treatment achieved a high cure rate in colon carcinoma MC38, melanoma B16F10, and YUMM1.7 models (83%, 60%, and 48%, respectively). Finally, investigation into the immune landsc (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

The increased use of solar energy for power is anticipated to lead to the shift from traditional power sources to renewable energy sources. Photovoltaic (PV) is a promising technology due to its ability to directly convert sunlight into electricity with no pollution. Solar cells, specifically those based on metal halide perovskites (MHPs) have gained popularity recently due to their power conversion efficiency (PCE) that have increased dramatically over the past 15 years, from 3.8% to more than 26 %. The rapid development in PCE is due to the advanced features that MHPs have such as cost-effective and easy processing, high absorption coefficient, large diffusion length, and low exciton binding energy. In particular, the purpose of this study is to develop solution-processed perovskite solar cells (PSCs) by tuning film morphology and optoelectronic properties of metal halide perovskites incorporated with processing additives, thereby optimizing the performance of PSCs. To maximize the potential of perovskite, controllable crystallization is crucial for producing high-quality perovskite thin films with fewer structural defects and additive engineering is a facile and effective method among other techniques. We mainly investigated the effects of various processing additives on the MHPs based on MAPbI3 perovskite (where MA is CH3NH3) and correlate PCE in term of film morphology, crystallinity, photocurrent hysteresis, optoelectronic properties, device performance and stability of PSCs.

Master of Science in Engineering, Youngstown State University, 2024, Department of Electrical and Computer Engineering

As part of this project, a complex terahertz (THz) antenna was fabricated using two-photon polymerization (2PP), a highly precise additive manufacturing method. The design and rigorous simulation testing were conducted using Ansys HFSS, with a focus on achieving minimal losses. Special emphasis was placed on impedance matching, confirmed by the S11 parameter showing minimal power reflection over a large part of the THz band. The antenna was fabricated using OrmoComp, a hybrid polymer. A significant portion of the thesis is dedicated to fine-tuning the intricate fabrication steps necessary for producing complex designs, demonstrating the capability to also fabricate simpler structures. The most significant outcomes of this work on the highly directional THz antenna are the optimized process parameters such as slicing direction, way of printing, power and speed settings of laser for 2PP and finally development time of post processing, which enabled the production of the complex structure. The fidelity of the final fabricated design was verified using electron and light microscopy.

Doctor of Philosophy, University of Akron, 2024, Polymer Science

Polymer-based coacervates can be prepared from a large variety of compositions. This provides versatility to coacervates as a material platform, but can also make them difficult to characterize, especially when other molecules or biologics are used in the same solution. The Joy lab has previously developed a platform to make thermoresponsive coacervating polyesters in a modular fashion. This allows us to make incremental changes to the coacervate structure and thus better observe how the structure affects the properties in various applications. In this work, we look at coacervates for hemostatic materials for non-compressible torso hemorrhage, and as sustained release drug delivery vehicles for colchicine release. Through a variety of experimental methods, our goal is to link structural changes in the coacervating polyester to the performance of the coacervate. The performance of our hemostatic coacervate was evaluated using clotting time tests, hemolysis tests, and rheology to determine how our materials interact with blood components. The trend in this data was further confirmed with in vivo mouse model studies which showed that the coacervates can perform well as hemostatic materials, and that the in vitro studies can effectively screen materials. We have also shown that amines in our coacervates are not effective and contrary to expectations and literature may increase bleeding times. To better predict coacervate properties on drug release, we employ NMR techniques such as STD and DOSY to better understand the strength of interactions between the coacervate and drug. The final drug release study confirms our NMR findings, and while the NMR techniques are not easily quantifiable, they do show an excellent relative predictability which can also be used to screen materials for an application. Ultimately, the tools employed for understanding coacervate performance enhance our understanding of their behavior in applications such as hemostasis and sustained (open full item for complete abstract)

PhD, University of Cincinnati, 2024, Engineering and Applied Science: Chemical Engineering

The tremendous success of messenger RNA (mRNA) vaccines has highlighted RNA therapeutics and their potential to address various diseases including cancer, infectious diseases, auto-immune diseases, etc. RNA therapeutics are enabled by lipid nanoparticles (LNPs), the most clinically advanced delivery system to date. Despite the success of LNP-containing mRNA vaccines, additional efforts are needed to further this technology for extra-hepatic delivery to various organs. Similarly, additional efforts are required to optimize the delivery system to mitigate the adverse effects caused by the administration of LNP-based vaccines. This dissertation focuses on developing an ionizable lipid-based lipid nanoparticle system that can be delivered with a lower total lipid dosage while maintaining the potency of the delivery system. This approach could help reduce the side effects associated with LNP-based delivery systems while delivering the same potency compared to single-nitrogen-based delivery systems. In this study, a library of lipids containing two nitrogen atoms in their structure was designed and synthesized. This lipid design was evaluated for potency against Jurkat T cells in vitro. The top-performing lipids were optimized by further substituting cholesterol with cholesterol analogs and their mechanism for endolytic pathways was evaluated. LNPs containing cholesterol performed better than their analogs. The top three performing LNPs showed similar cell uptake and endolytic mechanism. The top-performing LNPs were tested in vivo, and they showed potency in vivo. However, these lipids were less potent compared to the positive control in vivo. Another set of lipids containing two nitrogen atoms in their lipid backbone was designed and synthesized. The library of lipids was evaluated in vitro against Jurkat T cells and the top-performing LNPs were identified. The top-performing LNPs were optimized by varying the components of the LNP with their analogs. (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Electrical and Computer Engineering

An exciton is an electrically neutral quasiparticle that consists of an electron and a hole attracted to each other by the Coulombic force of attraction due to the opposite charge of the constituent pair. Exciton can form with the absorption of a photon into a material (insulator or semiconductor) as an intermediate state which can soon dissociate and produce photocarriers i.e., electron and hole under suitable condition. Normally a photon with above bandgap energy would get absorbed into any material of interest, but under an applied electric field a photon with below bandgap energy can be absorbed due to band bending as the wave function of the constituent electron and hole leak respectively from the Conduction Band and Valance Band into the forbidden region. This absorption process is known as the Franz-Keldysh (FK) effect. In Wide Bandgap Material (WBM)s such as Gallium Nitride (𝐺𝑎𝑁) and Beta-phase of Gallium Oxide (𝛽 − 𝐺𝑎2𝑂3) the FK effect is dominated by the formation and later dissociation of exciton. The below bandgap photon absorption via intermediate exciton state can be a process of general interest to explain the below bandgap photoresponsivity of the WBM under study. The understanding of exciton physics in this context can be utilized to engineer important applications such as to accurately detect and quantify the local electric field and the onset of breakdown behavior of the material which can help in designing Radio Frequency (RF) and power electronic devices with high reliability and stability. This dissertation looks at the excitonic physics of Wide Bandgap Materials i.e., 𝐺𝑎𝑁 and 𝛽 − 𝐺𝑎2𝑂3 with the objective to explain the experimentally observed photoresponsivity characteristics through eXciton Franz Keldysh (XFK) effect. Application of the exciton mediated below bandgap photon absorption physics in mapping out the electric field variation of 𝐺𝑎𝑁 p-n diode and 𝛽 − 𝐺𝑎2𝑂3 Schottky diode with applied external voltage are also d (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2024, Chemical Engineering

Thermoplastic elastomers (TPE) are a set of materials with characteristics of elastomers and thermoplastics. There is an increasing demand for polymers to be processed into three dimensional porous constructs for tissue engineering. Aliphatic polyester-based, poly(butylene succinate-co-dilinoleic succinate) (PBS-DLS) and polyisobutylene-based, poly(alloocimene-b-isobutylene-b-alloocimene) thermoplastic elastomer copolymers and their development will be presented for end use as biomaterial-based therapies in this dissertation. Electrospun fibrous scaffolds are favored for tissue engineering for their micro-structured networks creating a high surface area to volume ratio and this high interconnected porosity. These properties help mimic natural tissue structure for better tissue integration and diffusion through the network. Applying thermoplastic elastomers as scaffolds offers materials whose material properties can be tailored for specific applications. This dissertation presents work to advance biodegradable aliphatic copolymers for tissue scaffolds, and polyisobutylene copolymers for drug delivery. Cardiac soft tissue regenerations strategies employ biodegradative copolymers for cell delivery. Completely bio-based and biodegradable PBS-DLS copolymers have shown great potential for coiled 3D scaffolds for cardiac applications. This dissertation presents the kinetics of a step enzymatic polycondensation of PBS-DLS copolymers with varying feed ratios. 1H NMR and SEC results found that hydrophobic soft segment DLS was incorporated into the hard segment PBS within the first 3 hours. After which, the pressure was increased during second stage and complete DLS incorporation and high Mn oligomers occurred between 24 and 48 hours. MALDI-ToF analysis showed that the lower molecular weight fractions cyclic formation of long PBS sequences are favored during early stages of reactions. Poly(styrene-b-isobutylene-b-styrene) is currently used as the coating on the Taxus coronary (open full item for complete abstract)

Master of Science (M.S.), University of Dayton, 2024, Chemical Engineering

There is a continuous thrust for cleaner and more sustainable alternatives for energy conversion with the increasing global energy demand. Among them, photovoltaics, specifically thin film solar cells are highly promising and are one of the fastest growing clean energy technologies in the United States. This research presents the synthesis and characterization of a set of novel multinary copper chalcogenide semiconductor nanocrystals (NCs), CuZn2ASxSe4-x consisting primarily of earth-abundant elements for applications in photovoltaic devices. A modified hot-injection method was used to synthesize these semiconductor NCs containing both S and Se chalcogens. The novelty of the new semiconductor NCs lies in the incorporation of multiple cations as well as two different chalcogen anions within the crystal lattice, which is an achievement from the materials synthesis aspect. The composition-controlled optical and photoluminescence properties of the CuZn2ASxSe4-x NCs were investigated via multi-modal material characterization including x-ray diffraction (XRD), ultraviolet-visible (UV-vis) spectroscopy, and photoluminescence spectroscopy (PL). The crystal structure, as determined from the XRD primarily consisted of the metastable wurtzite (P63mc) phase. The NCs exhibited direct band gap in the visible range that could be tuned both by varying the group III cation within the composition as well as the ratio of S/Se, based on the Tauc plot obtained from the UV-vis characterization. This work lays the groundwork for future investigations into the practical applications of copper chalcogenide NCs in solar energy conversion.

Doctor of Philosophy (PhD), Ohio University, 2024, Chemical Engineering (Engineering and Technology)

Cancer metastasis is a multistep cascade often associated with interactions between adhesion molecules expressed on the vascular endothelium and cognate ligands expressed on circulating tumor cells. E-selectin is a major adhesion molecule expressed on the endothelium, and there are numerous literature reports that interaction between E-selectin and E-selectin ligands can contribute to cancer metastasis. However, only a few E-selectin ligands have been identified on breast cancer cells. On the other hand, nucleolin has been reported to be involved in many diseases including cancer. Previously, cell surface nucleolin was identified as an L-selectin ligand under shear stress conditions for head and neck cancer cell lines, and exosomes from hematopoietic stem/progenitor cells have been reported to express E-selectin ligand activity. Therefore, it is hypothesized that breast cancer cells express cell surface nucleolin as an E-selectin ligand, and their exosomes express E-selectin ligand activity. The first aim is to determine if cell surface nucleolin acts as an E-selectin ligand on breast cancer cells. Using flow cytometry and immunofluorescence experiments, nucleolin is shown to be expressed on the surface of four common cell line models of breast cancer (BT-20, MDA-MB-468, MDA-MB-231 and Hs578t). Parallel plate flow chamber experiments show that cell surface nucleolin is a functional E-selectin ligand at a certain shear stress, and BT-20 and MDA-MB468 human breast cancer cells adhesively interact with endothelial E-selectin via cell surface 4 nucleolin under flow conditions. Furthermore, sialidase treatment experiments indicate BT-20 and MDA-MB-468 cell surface nucleolin is a sialidase-sensitive E-selectin ligand under shear flow. The second aim of this dissertation research is to determine if breast cancer exosomes express E-selectin ligand activity. Exosomes are small extracellular vesicles (40-150 nm in diameter) secreted b (open full item for complete abstract)

Doctor of Philosophy, University of Akron, 2024, Polymer Engineering

Two-dimensional (2D) nanomaterials, such as graphene and transition metal dichalcogenides have been at the forefront of materials science due to their excellent and tunable mechanical, electrical, thermal, and optical properties. But they also have limitations including processability, scalability, and high cost, which constrain their applications in many fields. One strategy to overcome such limitations is to integrate 2D nanomaterials with other functional components including polymers and metallic nanostructures. The synergistic interactions between those components can lead to unprecedented properties. In this research, we focus on how to design functional nanocomposites based on the integration of 2D nanomaterials and other components, with targeted applications in solid lubrication and filtration/molecular separation. In the first study, we demonstrated that by integrating graphene oxide and polydopamine into sprayable nanocoatings, they can substantially enhance the filtration performance of filters based on polymer fiber network. In the second study, we showed that by in situ synthesis of graphene/titanium oxide hybrid nanosheets and transforming them into nanoscrolls, they can act as high-performance solid lubricants due to the high stability and significantly reduced contact area. In the third study, we demonstrated that the integration of 2D Fe2O3 nanosheets and graphene by a scalable microwave-assisted method, high-performance solid lubricants can be created, which substantially reduced the friction between steel-to-steel or steel-to-silicon. This research provides insight into the rational design and synthesis of functional 2D nanocomposites and can be further explored in areas including energy conversion/storage, catalysis, and advanced manufacturing.

Doctor of Philosophy, Case Western Reserve University, 2024, Biomedical Engineering

Ultrasound (US) is safe and low-cost relative to other imaging technologies, making it an increasingly popular diagnostic modality. US contrast is often limited by relatively low differences in acoustic impedance in the body, necessitating the use of contrast agents like microbubbles (MBs; ~1-10 µm diameter) which are intravenously injected and used to compensate for low contrast in conventional B-mode US imaging. The large size of MBs, however, limits their applications to the blood pool. In many diseases, including cancer, information beyond the blood pool is needed for diagnosis and staging. For instance, in many cancers (e.g. prostate, mammary, ovarian etc.), tumors are characterized by high vascular permeability and low lymphatic drainage, which increases the potential for enhanced permeability and retention (EPR) of macromolecules (~200 nm). When present, EPR leads to the tumor-localized accumulation of nano-agents. Nanobubbles (NBs) are new-age submicron bubble agents (100-500 nm diameter) capable of extravasation beyond the vascular network while providing enhanced US contrast similar to MBs. Recently, our group showed that active targeting of NBs to prostate specific membrane antigen (PSMA) rapidly and selectively enhances tumor accumulation and retention. These processes were visualized in real-time with clinical US. This project established NBs as a sensitive detection tool in the diagnosis of PSMA-positive prostate cancer due to localized NB accumulation, reduced diameter and higher number density (NBs per volume) of NBs compared to MBs of similar composition. Together, these points enable: 1) contrast visualization of small capillaries with higher fidelity, and 2) imaging of extravascular cellular targets reached via extravasation of NBs in leaky blood vessels while employing 3) a safe and widely accessible imaging modality. Together, contrast enhanced ultrasound (CEUS) using NBs (NB-CEUS) is a detection method with high biocompatibility and high safe (open full item for complete abstract)

Master of Sciences (Engineering), Case Western Reserve University, 2024, Materials Science and Engineering

Aerosol jet printing (AJP) offers a unique solution to fabrication challenges for microelectronic devices due to its microscopic feature resolution, rapid prototyping capabilities, and ability to print on curved surfaces. However, AJP is challenged by a complex set of interrelated process parameters which must be carefully adjusted to achieve desired print properties. A series of studies were conducted to investigate the effects of AJP parameters on properties of silver nanoparticle ink flexible electronics, and to define an optimized set of parameters to achieve desired performance metrics. Specimens were characterized via optical microscopy, profilometry, electrical testing, static bend testing, and focused ion beam sectioning. It was found that silver nanoparticle ink retained chemical and particle size properties over a period of ~25 weeks. The effects of sintering parameters were investigated and it was determined that 175 °C marks a threshold sintering temperature below which prints did not conduct, but above, print conductance increased and microstructure showed densification and grain growth. A 65°C platen temperature was found to mitigate both spreading and excessive drying of ink. The effects of individual AJP process parameters on deposition thickness and conductance were evaluated. Finally, an orthogonal array optimization study was conducted to arrive upon a set of optimized printing parameters including aerosol and sheath gas flow, atomizer voltage, print speed, and platen temperature. Findings can be applicable to future works seeking to hasten the adaptation of aerosol jet printing to specific applications.

Doctor of Philosophy (PhD), Ohio University, 2024, Chemistry and Biochemistry (Arts and Sciences)

The cardiovascular system is mainly regulated by nitric oxide (NO). A reduction in its synthesis or bioavailability might underlie the impaired endothelium-dependent vasodilatation, which is observed in the blood vessels of individuals with cardiovascular disease (CVD). The dysfunction of endothelium, which is a main characteristic of vascular aging, has been associated with low NO production and high production of cytotoxic peroxynitrite (ONOO-). Thus, the ratio of NO to ONOO- is an indicator of endothelial dysfunction. Moreover, vascular NO is produced by an enzyme called (endothelial nitric oxide synthase (eNOS), and its gene exhibits high polymorphism. However, it is unclear whether polymorphisms or haplotypes in the eNOS gene affect the NO production, ONOO- production, and eNOS coupling, as well as how aging impacts these haplotypes. The influence of the eNOS haplotype (consisting of single nucleotide polymorphisms (SNP) in the promoter region (T-786C) and (C-665T) and exon 7 (Glu298Asp) and a variable number of tandem repeats (VNTR) in intron 4 (4a/4b/4c)) on the production of NO and ONOO- and eNOS coupling was investigated. Sanger sequencing and DNA electrophoresis were used to detect SNPs and VNTRs in the samples, respectively. To evaluate the production of NO and ONOO- , nanosensors were used to determine the maximal concentrations of NO and ONOO- and traditional and low-temperature SDS-PAGE to evaluate the expression of eNOS and the eNOS dimer/monomer ratio, respectively. Interestingly, these results indicated that the eNOS haplotype (H5) combining the “T T/C C 4 4b” of the G894T, T-786C, C-665T, and 27 bp VNTR a/b/c is more susceptible to endothelial dysfunction. Compared with other haplotype samples, it had lower [NO]/[ONOO-] and higher eNOS expression with reduced eNOS dimer/monomer (P < 0.005). These findings have important implications for understanding the genetic basis of cardiovascular disease and aging and may lead to new (open full item for complete abstract)

Doctor of Philosophy (PhD), Wright State University, 2023, Electrical Engineering

Since their invention in 1958, Integrated Circuits (ICs) have become increasingly more complex, sophisticated, and useful. As a result, they have worked their way into every aspect of our lives, for example: personal electronic devices, wearable electronics, biomedical sensors, autonomous driving cars, military and defense applications, and artificial intelligence, to name some areas of applications. These examples represent both collectively, and sometimes individually, multi-trillion-dollar markets. However, further development of ICs has been predicted to encounter a performance bottleneck as the mainstream silicon industry, approaches its physical limits. The state-of-the-art of today's ICs technology will be soon below 3nm. At such a scale, the short channel effect and power consumption become the dominant factors impeding further development. To tackle the challenge, projected by the ITRS (International Technology Roadmap for Semiconductors) a thinner channel layer seems to be the most viable solution. This dissertation will discuss the feasibility of using 2D (two-dimensional) materials as the channel layer. The success of this work will lead to revolutionary breakthroughs by pushing silicon technology to the extreme physical limit. Starting from graphene in 2004, 2D materials have received a lot of attention associated with their distinct optical, electrical, magnetic, thermal, and mechanical properties. In the year 2010, IBM demonstrated a graphene-based field effect transistor with a cut-off frequency above 100 GHz. The major challenge of applying graphene in large-scale digital circuits is its lack of energy bandgap. Other than carbon, a variety of graphene-like 2D materials have been found in various material systems, like silicene, germanene, phosphorene, MoS2, WS2, MoSe2, HfS2, HfSe2, GaS, and InS, etc. Among all the 2D materials, silicene appears to be the most favored option due to its excellent compatibility with standard silicon technology. Simil (open full item for complete abstract)

Doctor of Philosophy (PhD), Ohio University, 2024, Mechanical and Systems Engineering (Engineering and Technology)

The world is currently experiencing a shortage of semiconductor chips. This shortage is affecting different industries that rely on electronic components that involve semiconductor chips to manufacture their products. Due to the shortage of chips, manufacturers are unable to complete the final assembly of their products, resulting in a delay in delivering the finished products to their customers. To address this issue, the US Congress passed the "Creating Helpful Incentives to Produce Semiconductors (CHIPS) and Science Act of 2022" on 9th August, 2022. This act aims to improve the competitiveness, innovation, and national security of the US. This dissertation focuses on addressing the chip shortage through the reduction of chronic semiconductor manufacturing process quality problems caused by wafer map surface defects. The proposed solution involves detecting mixed-type wafer map surface defect patterns using Ensemble Deformable Convolutional Neural Networks. The framework for defect detection proposed in this dissertation outperforms other machine learning models from literature, such as Conv-Pool-CNN, All-CNN, NIN-CNN, DCNN-v1, and DCNN-v2, in terms of F1-score. The proposed framework uses an industrial wafer map dataset (MixedWM38) from a semiconductor wafer manufacturing process to train the base models for the ensemble method. The results show that the proposed framework accurately identifies multi-pattern defects from the surface of wafer maps. This dissertation will contribute to advancing academic literature for the new field of detecting mixed-type defect patterns from the surface of wafer maps. Defects are indicators of process problems, and preventing quality defects in advance is the best approach to achieving positive yield. The efficient and accurate detection of wafer map mixed-type surface defect patterns is important for addressing chronic manufacturing process quality problems. The proposed framework can be used by semiconductor manufacturer (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2024, Biochemistry Program, Ohio State

This dissertation focuses on the development of Raman microscopy techniques to monitor nanoparticle uptake in cells. Chapter 1 introduces the importance of monitoring nanoparticle delivery for development of new therapeutic and sensing modalities. Nanoparticle characterization methods are then introduced, as these are important in determining nanoparticle properties and utility. Raman microscopy, the primary imaging technique used to monitor particle location in cells, is briefly described. Enhancement of Raman scattering (through either resonance of the laser with an electronic transition of the analyte or analyte adsorption to a plasmonic surface), are also briefly described, as these are critical to their respective applications in nanoparticle imaging. Chapter 2 focuses on Raman monitoring of lycopene-polysorbate 80 nanoparticles in cells. This research shows effective delivery of lycopene into cells. Raman imaging may be used to monitor the quantity, distribution, and isomerization of lycopene in cells. This information contributes to understanding both lycopene delivery to cells and the mechanism of action of lycopene for improving prostate cancer outcomes. Chapters 3 and 4 focus on monitoring gold nanoparticle delivery in cells. Chapter 3 discusses pH sensing methods for determining gold nanoparticle subcellular location. These methods are various data analysis approaches to interpreting the surface enhanced Raman scattering from 4-mercaptobenzoic acid to determine local pH in cells, aiming to infer nanoparticle endosomal escape from pH measurement. The pH method was complicated by the requirement of nanoparticle aggregation for detection, and a limited range of sensitivity of the reporter molecule to pH. Research then focused on spatially localizing every nanoparticle in a cell. Chapter 4 will describe the development of Raman microscopy-based single particle imaging, and a proof of concept in cells. The sensitivity and resolution achieved in this study ar (open full item for complete abstract)

Doctor of Philosophy (Ph.D.), University of Dayton, 2023, Electro-Optics

Photonics-based technologies are becoming increasingly common in consumer and industrial applications. Many of them require light manipulation such as intensity modulation, phase modulation or polarization control to achieve their desired functions. These require tunable optical materials. While liquid crystal-based tunable devices have been the defacto standard in most applications, the need for higher speeds, compact size, light weight, temperature stability, longevity and robustness have required researchers to explore alternate methods of achieving this tunability. This need forms the basic inspiration for this work. In this dissertation, a number of tunable and variable optical components have been designed, fabricated and demonstrated. This includes a continuously variable Fourier filter integrated with a photodetector array for multispectral detection, and tunable devices based on phase change materials (PCM) such as switchable Distributed Bragg Reflectors (DBR) using Ge2Sb2Te5 (GST), and switchable wire grid polarizers based on Vanadium dioxide (VO2). This dissertation also includes fundamental studies on the development and patterning of phase change materials including electrically addressable tungsten-doped GST, nano-patterned Sb2Se3, and direct laser patterning of GST films.

Master of Science in Engineering, Youngstown State University, 2023, Department of Electrical and Computer Engineering

This thesis investigates a novel terahertz (THz) antenna for advanced THz communications and a performance analysis of a balun design fabricated using two additive manufacturing methods and a traditional method. It proposes a THz antenna with a peak gain of 0.38 dB at 0.125 THz, suitable for MIMO systems due to its multi-directional radiation and broad impedance bandwidth. The study also compares PCB with screen-printing and aerosol jet printing manufacturing techniques for balun production, highlighting the performance of the design when printed on flexible and rigid FR-4 substrates. Significant findings include the critical role of substrate material on the balun's RF performance, with different materials affecting bandwidth and efficiency. The research presented contributes to the THz field by offering insights into design and manufacturing impacts on high-frequency communication devices, supporting the development of more efficient THz communication technologies.

Doctor of Philosophy, The Ohio State University, 2023, Mechanical Engineering

The extracellular matrix (ECM) is a 3D non-cellular polymer network that is present within all tissues and organs. The ECM is complex, dynamically remodeling, and crucial for maintaining homeostasis of the cellular microenvironment. The ECM provides not only a physical scaffold for cells, but also regulates various processes such as proliferation, migration, and differentiation of cells. Crosstalk between ECM constituents can occur either physically where cell-ECM interactions are regulated by the biophysical properties of the host tissue, or biochemically, through signaling molecules. On a biochemical level, interactions can happen through direct cell signaling, or through the ECM-mediated capture and release of potent signaling molecules. Studies have reported the effect of certain circulating molecules, like extracellular nucleic acids, and platelet derived growth factor (PDGF) in disease progression, such as in the case of cancer, cardiovascular, fibrotic, Parkinson, Alzheimer, and kidney diseases. On a biophysical level, modulation of the mechanical properties of the ECM by cells is believed to significantly influence the progression of certain diseased tissue such as in fibrosis, healing wounds, or the stroma of tumors, all of which are known to exhibit ECM remodeling through the cross-linking of fibrillar collagen and/or deposition of non-collagenous ECM. In addition, slowly moving interstitial flow through the ECM plays a major role in modulating cancer cell migration that may promote metastasis by redistributing morphogens, leading to chemotaxis, or through the activation of cell-surface mechanosensors, such as focal adhesion proteins, that promote cell motility. Here, I present hybrid in vitro systems that utilize microfluidic devices and DNA-based nanoscale sensors that enable measuring biochemical cues and biophysical forces in the ECM at a sub-cellular level. This thesis is organized into three parts. Part 1 covers engineering the ECM with DNA-b (open full item for complete abstract)