Engineering Commons^™

Development Of Novel Inks And Approaches For Printing Tissues And Organs, Shen Ji

Dissertations

Tissue engineering is a multidisciplinary field that investigates and develops new methods to repair, regenerate and replace damaged tissues and organs, or to develop biomaterial platforms as in vitro models. Tissue engineering approaches require the fabrication of scaffolds using biomaterials or fabrication of living tissues using cells. As the demands of customized, implantable tissue/organs are increasing and becoming more urgent, conventional scaffold fabrication approaches are difficult to meet the requirements, especially for complex large-scale tissue fabrication. In this regard, three-dimensional (3D) printing attracted more interest over the past decades due to its unrivaled ability to fabricate highly customized tissues or …

Experiments And Modeling Of The Chemo-Mechanically Coupled Behavior Of Polymeric Gels, Nikola Bosnjak

Dissertations

Polymeric materials consist of mutually entangled or chemically crosslinked long njitmolecular chains which form a polymer network. Due to their molecular structure, the njitpolymeric materials are known to undergo large deformation in response to various njitenvironmental stimuli, such as temperature, chemical potential and light.

When a polymer network is exposed to a suitable chemical solvent, the solvent molecules are able to diffuse inside the network, causing it to undergo a large volumetric deformation, known as swelling. In addition to volumetric deformation, this process involves the chemical mixing of the polymer network and solvent molecules, and is typically environmentally responsive. A …

Blast Shock-Wave Characterization In Experimental Shock Tubes, Sudeepto Kahali

Dissertations

Blast-induced traumatic brain injuries have affected U.S. soldiers deployed for extended periods in the gulf and Afghanistan wars. To identify the biomechanical and biochemical mechanisms of injury, critical in the identification of diagnostic and therapeutic tools, compressed gas-driven shock tubes are used by investigators to study shockwave-animal specimen interactions and its biological consequences. However, shock tubes are designed and operated in a variety of geometry with a range of process parameters, and the quality of shock wave characteristics relevant to field conditions and therefore the study of blast-induced traumatic brain injuries suffered by soldiers is affected by those conditions. Lab-to-lab …

Cycloidal-Drive Joint Design For Wearable Exoskeletons, Abhi J. Rawal

Theses

This thesis's scope was to construct a highly back drivable and compact joint design that can be used for wearable exoskeletons specifically designed to assist with rehabilitation. A compact cycloidal gear transmission was designed to satisfy the compactness requirement while ensuring the minimum torque is required for backdriving the mechanism. The joint was designed based on the compact cycloidal drive specifications, and the backdrivability test was performed to measure the minimum torque required (1.20 Nm) to backdrive. The joint design incorporates various important features such as rotation lock feature to prevent hyperextension, a housing design that offers the benefit of …

Investigating The Combined Effects Of Whole Body Vibration And Vestibular Stimulation On Spasticity And Dystonia In Cerebral Palsy, Peter A. Michael

Dissertations

This study identifies and addresses three voids and potential shortcomings associated with the classification, assessment and management of Cerebral Palsy (CP). These concerns should not undermine the significant advancement that has been made in this specific branch of rehabilitation, but addressing them is necessary. Cerebral Palsy is a group of motor impairments due to hypoxic-ischemic brain damage around the time of birth and very commonly manifests as excessive muscle tone and poor motor control. There are classifications within CP including spasticity and dystonia.

First, a level of discrepancy is present in the classification of CP between the clinical and research …

Comparison Of Longitudinal Changes In Resting State Functional Magnetic Resonance Imaging Between Alzheimer’S And Healthy Controls, Berk Can Yilmaz

Theses

Resting State Functional Magnetic Resonance Imaging (rs-fMRI) is a technique that is widely used for analyzing brain function using different approaches and methods. This study involves rs-fMRI analysis of Blood Oxygenation Level Dependent (BOLD) signals acquired from Alzheimer’s disease (AD) Patients and Healthy Controls (HC). Each subject in the study had both functional and anatomical images with at least one rs-fMRI scan with their Anatomical (T1) scans. Previous rs-fMRI studies have demonstrated that AD shows differences in Amplitude of Low Frequency (<0.1 Hz) Fluctuations (ALFF), and Regional Homogeneity (ReHo) measures according to HCs.

The aim of the study is to investigate individual and group level differences using ReHo and mALFF related …

Biomechanical Loading Changes Between Species In Mild Blast-Induced Traumatic Brain Injury, Jose Juan Rodriguez

Dissertations

Blast-induced traumatic brain injury (bTBI) has become one of the leading injury modalities in military personnel and is considered a signature injury in veterans returning from conflicts in the Middle East. One of the main concerns in studying bTBI is translating animal experiments to clinical applications that can service veterans. Significant advances have been made using animal models in relating external shock waves to emerging neuropathophysiological and behavioral outcomes. However, it is unknown if these results are applicable to humans; and if so, can an interspecies transfer function be developed based on size, shape, and material response. This work aims …

A Model For Thermal Diffusion And Local Tissue Damage From The Measurement Of Temperature In Electrosurgical Incision, Marek Vira

Theses

The extremely high temperatures applied over extremely short time intervals that are characteristic of electrosurgery result in a unique tissue damage pattern. Cesarean delivery and hysterectomy, the two most frequently performed procedures in obstetrics and gynecology (OB/GYN), commonly employ electrosurgical incision. While it is controversial, it has been suggested that tissue damage produced by electrosurgery could increase surgical site infection rates. While recommendations for the settings in the use of the electrosurgical unit do exist, there is no current technique for real time assessment of the viability of tissue around the site of the electrosurgical incision. Current methods for analyzing …

Modulation Of Cerebellar Purkinje Cell Activity With Low Intensity Electric And Ultrasound Stimulation, Ahmet S. Asan

Dissertations

Non-invasive brain stimulation (NIBS) techniques garner significant interest due to their potential to offer instantaneous and region-specific treatments to neurological disorders. The cerebellum is one of the target sites for NIBS methods due to its central role in motor and cognitive functions. Among several modulation techniques, transcranial electric stimulations (tEs), in particular, transcranial direct and alternating current stimulations (tDCs/tACs), and low intensity focused ultrasound stimulation (LIFUS) show encouraging outcomes in clinical applications. tDCs and tACs are favored due to their low cost and accessibility while LIFUS offers high spatial resolution and deeper penetration without affecting the surrounding structures. In order …

Mechanical Characterization Of Animal Derived Starting Materials For Tissue Engineering, Bin Zhang

Dissertations

Animal derived starting materials are well established in the production of Tissue Engineered Medical Devices. Porcine specifically can be found in products ranging in application from hernia repair to breast reconstruction. Although this material has been largely accepted in the Tissue Engineering industry, little is known of its material properties and mechanical characteristics. A review of the scientific literature describes limited mechanical measures only on uncontrolled research grade material. The objective of this work is to mechanically characterize porcine starting material used in the medical device industry. Porcine skin is provided by Midwest Research Swine, LLC (MRS) an established supplier …

Scanless Optical Coherence Tomography For High-Speed 3d Biomedical Microscopy, Yahui Wang

Dissertations

Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging modality that has found applications in a wide range of biomedical fields, such as ophthalmology diagnosis, interventional cardiology, surgical guidance, and oncology. OCT can be used to image dynamic scenes, in quantitative blood flow sensing and visualization, dynamic optical coherence elastography, and large-scale neural recording. However, the spatiotemporal resolution of OCT for dynamic imaging is limited by the approach it takes to scan the three-dimensional (3-D) space. In a typical OCT system, the incident light is focused to a point at the sample. The OCT system uses mechanical scanners (galvanometers or …

Identification Of Neurobiological Mechanisms Associated With Attention Deficits In Adults Post Traumatic Brain Injury, Ziyan Wu

Dissertations

Traumatic Brain Injury (TBI) is one of the major public health concerns with approximately 70 million new cases occurring worldwide per year. It is often caused by a forceful bump, blow, or jolt to the head, resulting in brain tissue damage and normal brain functions disruption. All grades of TBI, ranging from mild to severe, can cause wide-ranging and long-term effects on affected individuals, resulting in physical impairments, and neurocognitive consequences that permanently affect their abilities to perform daily activities. Attention deficits are the most common persisting neurocognitive consequences following TBI, which significantly contribute to poor academic and social functioning, …

Neurobiological Markers For Remission And Persistence Of Childhood Attention-Deficit/Hyperactivity Disorder, Yuyang Luo

Dissertations

Attention-deficit/hyperactivity disorder (ADHD) is one of the most prevalent neurodevelopmental disorders in children. Symptoms of childhood ADHD persist into adulthood in around 65% of patients, which elevates the risk for a number of adverse outcomes, resulting in substantial individual and societal burden. A neurodevelopmental double dissociation model is proposed based on existing studies in which the early onset of childhood ADHD is suggested to associate with dysfunctional subcortical structures that remain static throughout the lifetime; while diminution of symptoms over development could link to optimal development of prefrontal cortex. Current existing studies only assess basic measures including regional brain activation …

Model-Based Deep Siamese Autoencoder For Clustering Single Cell Rna-Seq Data, Zixia Meng

Theses

In the biological field, the smallest unit of organisms in most biological systems is the single cell, and the classification of cells is an everlasting problem. A central task for analysis of single-cell RNA-seq data is to identify and characterize novel cell types. Currently, there are several classical methods, such as K-means algorithm, spectral clustering, and Gaussian Mixture Models (GMMs), which are widely used to cluster the cells. Furthermore, typical dimensional reduction methods such as PCA, t-SNE, and ZIDA have been introduced to overcome “the curse of dimensionality”. A more recent method scDeepCluster has demonstrated improved and promising performances in …