Digital Commons Network^™

Improved Contacts And Device Performance In Mos2 Transistors Using 2d Semiconductor Interlayers, Kraig Andrews

Wayne State University Dissertations

The rapid growth of modern electronics industry over the past half-century has been sustained by the continued miniaturization of silicon-based electronics. However, as fundamental limits approach, there is a need to search for viable alternative materials for next-generation electronics in the post-silicon era. Two-dimensional (2D) semiconductors such as transition metal dichalcogenides (TMDs) have attracted much attention due to their atomic thickness, absence of dangling bonds and moderately high carrier mobility. However, achieving low-resistance contacts has been major impediment in developing high-performance field-effect transistors (FETs) based on 2D semiconductors. A substantial Schottky barrier (SB) is often present at the metal/2D-semicondcutor interface, …

Customer Choice Modeling For Retail Category Assortment Planning And Product-Line Extension, Elham Nosratmirshekarlou

Wayne State University Dissertations

Growing competitiveness and increasing availability of data is generating great interest in data-driven analytics across industries. One of the areas that has gained a lot of attention is Customer choice modeling, which aims to explain the choices individual customers make in choosing from a set of products based on their preferences. While effective customer choice modeling is essential to a wide variety of application domains, including retail, it is challenging in practice due to limitations around the quality of the data available for modeling and potentially complex choice behaviors. This dissertation presents a hybrid modeling approach that relies on both …

Durability Performance Of Geopolymer Concrete Beams And Columns Exposed To Hygrothermal Environment, Najeb Hasen Sh Sawsi

Wayne State University Dissertations

Among the most important advances of research and technological development for viable applications of coal-fired fly ash, the development of new inorganic polymeric materials, named alkali activated cement or “Geopolymers”, seems to gain increasing attention during the last twenty years. The present investigation intends to study the effect of hot weather environments (either by changing relative humidity and temperature is kept constant, or by changing temperature but relative humidity is maintained same) on the durability performance of geopolymer concrete beams and columns. The study include the long term influence of moisture, high temperature, and combined hygrothermal conditions on the mechanical …

Computational Analysis Of Oxidative Stress In Endothelial Dysfunction: Insights On The Role Of Tetrahydrobiopterin, Ascorbate And Glutathione, Sheetal Kedar Panday

Wayne State University Dissertations

Oxidative stress and endothelial dysfunction are reported in the cardiovascular and neurovascular diseases. Oxidative stress is caused due to an increase in the generation of reactive oxygen (ROS) and nitrogen species (RNS) and incapacity of antioxidant systems to eliminate ROS and RNS. Endothelial dysfunction is characterized by a reduction in nitric oxide (NO) bioavailability. NO is constitutively produced by enzyme endothelial nitric oxide synthase (eNOS). A reduction in tetrahydrobiopterin (BH4), which is an essential cofactor of eNOS, can lead to eNOS uncoupling. There is complex interplay between the ROS/RNS and antioxidant system underlying pathophysiologies of vascular diseases, however our quantitative …

Development Of Rat Head Finite Element Model And Tissue Level Biomechanical Threshold For Traumatic Axonal Injury, Runzhou Zhou

Wayne State University Dissertations

Traumatic brain injury (TBI) is caused by local tissue deformation at the time of trauma, leading to neurological dysfunction. In the United States alone, 2.87 million people sustain a TBI each year, of which one-fifth results in death. Traumatic axonal injury (TAI) is a well-recognized consequence of every fatal head injury and more than 85% of vehicular crash-related blunt head injuries. The most common and important pathologic feature of TBIs are multifocal changes to axons in the white matter produced by rapid head acceleration/deceleration during a traumatic event with consequent local shear/tension on neural tissue and axons contributing to secondary …

Development Of Photoacoustic Tomographic Systems For Brain Hemorrhage Detection, Karl Kratkiewicz

Wayne State University Dissertations

Preterm neonates (age) and/or with low birth weight (

Photoacoustic imaging (PAI) is an imaging modality which derives its contrast from differences in optical absorption coefficients of tissue through laser irradiation and acoustic detection. Therefore, PAI derives its signal directly from optical absorbers such as blood; the critical component in a hemorrhage. We discuss operation and processing methods of our Verasonics Vantage system. We then investigate thermal safety of PAI in mouse model for various laser pulse repetitions rates and illumination duration. We then develop two photoacoustic tomographic systems for eventual translation to clinic for hemorrhage detection. One system being …

Enabling 3d Printing Technologies For Artificial Compound Eye System And Penetrating Neural Probes, Boshen Zhang

Wayne State University Dissertations

3D printing has become a useful and transformative method and has applications in many different fields, including organ printing, aerospace applications, and medical devices. With higher resolution, faster production speed, and more design flexibility, 3D printing technologies can lead to more novel devices and systems. In this research, two new techniques have been developed to enable 3D printing technologies for artificial compound eye system and penetrating glassy carbon neural electrode array.

This work focuses on developing new applications based on the SLA 3D printing process, which uses the liquid resin to create a solid 3D structure. The limitation of SLA …

Dynamic Resource Allocation For Coordination Of Inpatient Operations In Hospitals, Najibesadat Sadatijafarkalaei

Wayne State University Dissertations

Healthcare systems face difficult challenges such as increasing complexity of processes, inefficient utilization of resources, high pressure to enhance the quality of care and services, and the need to balance and coordinate the staff workload. Therefore, the need for effective and efficient processes of delivering healthcare services increases. Data-driven approaches, including operations research and predictive modeling, can help overcome these challenges and improve the performance of health systems in terms of quality, cost, patient health outcomes and satisfaction.

Hospitals are a key component of healthcare systems with many scarce resources such as caregivers (nurses, physicians) and expensive facilities/equipment. Most hospital …

In Vitro Atherosclerosis Disease Model Via The Ring Stacking Method, Cameron Brandon Pinnock

Wayne State University Dissertations

Creation of an in vitro atherosclerotic disease model using the novel Ring Stacking Method. Singular self-assembling tissue rings made up smooth muscle cells and fibrin hydrogel are stacked on one another to create a tissue engineered vessel. These biologically engineered blood vessels are then seeded with endothelial cells via combined static rotational and dynamic bioreactor in order to create a functional intima layer. Early stage atherosclerosis was induced via the addition of oxidized low-density lipoproteins (ox-LDL) to the fibrin hydrogel that creates the media layer of the engineered vessel. After the creation of the intima layer the engineered vessel was …

Error Correction For Automotive Telematics Systems, Samer Zakhem

Wayne State University Dissertations

One benefit of data communication over the voice channel of the cellular network is to reliably transmit real-time high priority data in case of life critical situations. An important implementation of this use-case is the pan-European eCall automotive standard, which has already been deployed since 2018. This is the first international standard for mobile emergency call that was adopted by multiple regions in Europe and the world. Other countries in the world are currently working on deploying a similar emergency communication system, such as in Russia and China. Moreover, many experiments and road tests are conducted yearly to validate and …

Development Of A Novel Cardiac Ischemia-Reperfusion Model In The Axolotl, Jeremy Tolentino Llaniguez

Wayne State University Dissertations

The Center for Disease Control’s National Center for Health Statistics data for mortality from diseases of the heart show the age-adjusted death rate has fallen from almost 600 deaths in the 1950s to just over 190 deaths per 100,000 U.S. residents today. With the recognized limitations of pharmacotherapy of myocardial infarction (MI), cell-based therapies have been undergoing rapid development and clinical testing. However, there is still no consensus about cell types, delivery routes, dosing and treatment schedules and pretreatment conditioning of cells prior to administration. Furthermore, a fundamental question remains unanswered about the reasons for the poor capacity for myocardial …

Study Of Grain Growth In Single-Phase Polycrystals, Pawan Vedanti

Wayne State University Dissertations

Materials with random microstructure are characterized by additional thermodynamic parameters, entropy and temperature of microstructure. It has been argued that there is one more law of thermodynamics: entropy of microstructure decays in isolated systems. This assertion has been checked experimentally for the process of grain growth which showed that entropy of grain structure decays indeed as expected. The equation of state for microstructure entropy has also been studied. In general, entropy of grain microstructure is expected to be a function of grain structure energy and the average grain size. Our experiments suggest that in fact, the equation of state degenerates …

Parylene Based Flexible Multifunctional Biomedical Probes And Their Applications, Zhiguo Zhao

Wayne State University Dissertations

MEMS (Micro Electro Mechanical System) based flexible devices have been studied for decades, and they are rapidly being incorporated into modern society in various forms such as flexible electronics and wearable devices. Especially in neuroscience, flexible interfaces provide tremendous possibilities and opportunities to produce reliable, scalable and biocompatible instruments for better exploring neurotransmission and neurological disorders. Of all the types of biomedical instruments such as electroencephalography (EEG) and electrocorticography (ECoG), MEMS-based needle-shape probes have been actively studied in recent years due to their better spatial resolution, selectivity, and sensitivity in chronical invasive physiology monitoring. In order to address the inherent …

Titanium Nitride Nanotube Electrodes Used In Neural Signal Recording Application And Neurotransmitter Detection, Gui Chen

Wayne State University Dissertations

Electrode probes are devices widely used for stimulating and recording neural cell signals in the neuroscience field, which can convert the ion potential generated by electrochemical activities into an electronic potential that can be measured by the external instrument systems. A stable neural interface that effectively communicates with the nervous system via electrode is much important for the robust recording and the long-term monitoring of the activity of the neural signals. These probes are designed to minimize tissue damage for superior signal quality. Each probe’s mechanical, geometric, and electrical characteristics are precise and highly reproducible for consistent, high-quality results. There …

Seed-Mediated Crystallization Of Charge-Transfer Complexes And Their Applications For Gas Sensing, Xuecheng Yu

Wayne State University Dissertations

The dissertation focused on controllable seed-mediated nucleaton of charge transfer complex, namely tetrathiafulvalene bromide ((TTF)Br) and Krogmann’s salts (KCP), and their applications in sensing. On gold nanoparticle (AuNP) decorated highly oriented pyrolytic graphite (HOPG) substrate, the presence of AuNP promotes the formation of charge transfer salt nanowires. The size of these nanowires, both (TTF)Br and KCP, were found to be confined by the size of AuNPs, shown by SEM and AFM characterization. On micro-disk electrodes, charge transfer salt nanowires were found to own a linear time dependency, by both SEM and in-situ optical microscopy. The micro-disk electrodes promoted higher crystallization …

Ac Conductivity Studies Of Polyethylene-Oxide-Garnet Type Li7la3zr2o12 Hybrid Composite Solid Polymer Electrolyte For Li-Ion Battery, Parisa Bashiri

Wayne State University Dissertations

Solid electrolytes including ceramics and polymers are considered to be the ultimate substitute for organic liquid electrolytes currently used in commercialized lithium ion batteries to address the safety concerns due to Li dendrite growth and internal short circuiting. However, low ionic conductivity due to high grain boundary resistance in ceramics and semi-crystalline nature of polymers has held back the solid electrolytes from being used in Li-ion batteries. Polyethylene oxide (PEO), complexed with a Li-salt, is a well-studied polymer electrolyte showing ionic conductivity properties at room temperature. However, the coexistence of amorphous and crystalline regions at room temperature (< Tm, the melting temperature) has

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Investigation Of Physiochemical Properties And Biocompatibility Of Amourphos Calcium Polyphosphate Hydrogel Doped With Antibiotics And Injectable Polymeric Dicalcium Phosphate Dihydrate Bone Cement, Yasaman Chehreghanianzabi

Wayne State University Dissertations

Amorphous calcium polyphosphate (ACPP) is an inorganic polymer ceramic. Here we use a simple method of preparing ACPP hydrogel in the presence of excess volume of water. Essentially, water availability to polyphosphate chains accelerates water molecule ingress and microstructural transformation of ACPP hydrogels. Antibiotic delivery capacity of ACPP hydrogel increases by the specific mixing and molding method, where the VCM has higher antibiotic encapsulation efficiency with the small burst release for the compressed discs. In part of this study, we investigate impact of ACPP hydrogel replacement by monomeric calcium phosphate on the quality of final product (dicalcium phosphate dihydrates (DCPD) …

Evaluation Of Far-Side Occupant Safety Based On Numerical Modeling, Syed Akhtar Imam

Wayne State University Dissertations

The objective of this study was to augment the knowledge of the far-side occupant injury biomechanics in side impact vehicle crashes. Most research studies conducted to investigate the far-side occupant injuries are through the field crash data for a better understanding of human impact responses, injury mechanisms, and injury tolerance levels. The data obtained from field data is also used in the development of injury mitigation technologies, such as safety belts, airbags, etc. A field data represents the injury outcome of an automotive crash, but it doesn’t leave behind enough information for in-depth knowledge. The use of cadaver is the …

Incorporating Cardiac Substructures Into Radiation Therapy For Improved Cardiac Sparing, Eric Daniel Morris

Wayne State University Dissertations

Growing evidence suggests that radiation therapy (RT) doses to the heart and cardiac substructures (CS) are strongly linked to cardiac toxicities, though only the heart is considered clinically. This work aimed to utilize the superior soft-tissue contrast of magnetic resonance (MR) to segment CS, quantify uncertainties in their position, assess their effect on treatment planning and an MR-guided environment.

Automatic substructure segmentation of 12 CS was completed using a novel hybrid MR/computed tomography (CT) atlas method and was improved upon using a 3-dimensional neural network (U-Net) from deep learning. Intra-fraction motion due to respiration was then quantified. The inter-fraction setup …

Advanced Electrodes And Electrolytes For Long-Lived And High-Performance Lithium-Sulfur Batteries, Deepesh Gopalakrishnan

Wayne State University Dissertations

ABSTRACT

ADVANCED ELECTRODES AND ELECTROLYTES FOR LONG-LIVED AND HIGH-PERFORMANCE LITHIUM-SULFUR BATTERIES

by

DEEPESH GOPALAKRISHNAN

August 2020

Advisor: Dr. Leela Mohana Reddy Arava

Major: Mechanical Engineering

Degree: Doctor of Philosophy

Lithium – Sulfur (Li-S) batteries have received much attention and considered as a promising candidate for next generation energy storage devices because of their high theoretical energy density (≈2600 Wh kg‒1) and environmental friendliness. However, the uncontrollable growth of lithium dendrites in the lithium metal anode and the fatal effect of polysulfide shuttle hinder their practical applications. The formation of dendrites during repeated Li plating/stripping processes results in: reduced Li availability …

Stochastic Programming Models For Electric Vehicles’ Operation: Network Design And Routing Strategies, Seyed Sajjad Fazeli

Wayne State University Dissertations

Logistic and transportation (L&T) activities become a significant contributor to social and economic advances throughout the modern world Road L&T activities are responsible for a large percentage of CO2 emissions, with more than 24% of the total emission, which mostly caused by fossil fuel vehicles. Researchers, governments, and automotive companies put extensive effort to incorporate new solutions and innovations into the L&T system. As a result, Electric Vehicles (EVs) are introduced and universally accepted as one of the solutions to environmental issues. Subsequently, L&T companies are encouraged to adopt fleets of EVs. Integrating the EVs into the logistic and transportation …

Spatiotemporal Release Of Growth Factors In A Biomaterial-Focused Organotypic Spinal Cord Injury Model, Elizabeth Mays

Wayne State University Dissertations

Over 17,000 people per year in the United States sustain a spinal cord injury (SCI) for which there is no gold standard of care and life-long complications. SCI is a complex wound environment with various growth factors (GFs), cellular activity, and scar formation at various timepoints. For example, basic fibroblast growth factor (bFGF) is released immediately to protect local support cells, namely oligodendrocytes (OLs). Brain derived neurotrophic factor (BDNF) has peak expression at 2-3 days in mice and 5-7 days in humans, and aids axonal growth across the injury site. Incidentally this is around the same time as M1 macrophage …

Design Thinking & Strategic Product Planning For Highly Engineered Products, Shannon Dare Wayne

Wayne State University Dissertations

This paper offers an integrated framework to systematically address routine challenges plaguing early product development for highly engineered and complex products, such as automobiles. The framework includes up-front strategic product planning leveraging ‘design thinking’ and ‘design execution’ through a structured process to enable adaptation under uncertainties in the product development lifecycle for customer delight and program success. Included is product planning, from fuzzy front-end until product launch, and prioritizing aligned strategic initiatives while integrating design thinking throughout the process. We also discuss two real-world case studies to emphasize the efficacy of the framework and to demonstrate practical examples of how …