Biomedical Engineering and Bioengineering Commons^™

Feedforward And Feedback Signals In The Olfactory System, Srimoy Chakraborty

Graduate Theses and Dissertations

The conglomeration of myriad activities in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular electrophysiological measurements revealed distinct frequency bands of oscillations in OB and aPC. However, how these oscillatory fluctuations help the animal to process sensory input is not clearly understood. Here we show high frequency oscillations in olfactory bulb carry feedforward signals to anterior piriform cortex whereas feedback from the aPC is predominantly …

Stability Analysis Of A More General Class Of Systems With Delay-Dependent Coefficients, Chi Jin, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu

SIUE Faculty Research, Scholarship, and Creative Activity

This paper presents a systematic method to analyse the stability of systems with single delay in which the coefficient polynomials of the characteristic equation depend on the delay. Such systems often arise in, for example, life science and engineering systems. A method to analyze such systems was presented by Beretta and Kuang in a 2002 paper, but with some very restrictive assumptions. This work extends their results to the general case with the exception of some degenerate cases. It is found that a much richer behavior is possible when the restrictive assumptions are removed. The interval of interest for the …

Design Of Microporous Membranes For The Development Of Brain-On-Chip Devices, Andre Figueroa Milla

Biomedical Engineering Undergraduate Honors Theses

Traumatic brain injuries (TBIs) are a major global health concern that have an economic impact of $60 billion in the United States in related costs annually. Developing drugs for TBI treatment is an approach that currently faces limitations involving the permeability of the blood-brain barrier (BBB). The BBB naturally limits molecules from reaching the brain as a protective mechanism against disease, acting as a barrier during drug delivery. Understanding the BBB mechanically and chemically following a TBI could potentially assist future studies to alleviate the symptoms and long-term effects of TBI by pharmaceuticals. The Mechanobiology and Soft Materials Laboratory (MSML) …

A Bioinstrumentation Active Learning Educational Module: The Design Of A Working Temperature Sensor Using A Ntc Thermistor, Baylor Bush

Biomedical Engineering Undergraduate Honors Theses

The Department of Biomedical Engineering at the University of Arkansas has continued to develop over the years, with more students enrolling in the program each year. Within the first biomedical engineering course, Introduction to Biomedical Engineering, various topics are introduced to students, and the topic of bioinstrumentation has been one of the most complex and difficult topics for students to comprehend through just a few lectures. In order to aid students in grasping these intricate concepts, an active learning module was developed in which students can work in groups to build a simple thermistor circuit as a temperature sensor. The …

Autofluorescence To Study The Effects Of Acid Concentration On Cellular Metabolism In Vitro, Robin L. Raley

Chemistry & Biochemistry Undergraduate Honors Theses

Ultraviolet (UV) radiation-induced sunburns and their accompanying afflictions are a growing public health concern in the United States. There is a need for techniques that can accurately and non-invasively characterize the physiology of sunburned skin tissue directly after UV-damage and applying a topical skin treatment to relieve pain and promote healing. Two-photon excited fluorescence (TPEF) microscopy and fluorescence lifetime imaging (FLIM) can be used to investigate metabolic processes in live cells through endogenous fluorescence of the cofactors, NADH and FAD. These methods employ the optical redox ratio of FAD/(NADH+FAD), mean NADH lifetime, and the separation of the free and bound …

Comparing The Effects Of Fibroblast Growth Factors On Growth Rate Of Human Fibroblast Cell Lines, Tasha Repella

Biomedical Engineering Undergraduate Honors Theses

Numerous studies have demonstrated the usefulness of growth factors in medium formulations to promote proliferation and viability of human fibroblasts in laboratory settings. However, due to the differences in the source and age of fibroblasts, the ability of growth factors like hFGF1 to promote proliferation varies. Equally difficult is the ability of hFGF1 to promote proliferation of diseased fibroblasts due to complexities associated with specific mitochondrial diseases. In this context, we decided to evaluate the potential for novel hyper stable growth factors super hFGF and hFGF1 (shFGF and hFGF1 respectively), to contribute to proliferation of different normal and diseased fibroblasts. …

Development Of A Model For Accelerated Fatigue Testing In Venous Valves, Olga Brazhkina

Biomedical Engineering Undergraduate Honors Theses

Malfunctioning venous cause issues ranging from cosmetic to life threatening situations for millions of people in the U.S. (1). Venous valve bioprosthetics often fail due to a loss in leaflet tissue flexibility following chemical fixation of donor tissue (2). A viable solution for testing venous valves prior to and post chemical fixation is in high demand for the development of a more durable prosthetic replacement. As a result, this research aims to create a fatigue apparatus that provides a means to model the durability of venous valves. The design criteria for this project included modeling physiological conditions in an accelerated …

Modeling And Validation Of Tissue Optical Properties In The Photon Transport Regime, Katelyn Heath

Biomedical Engineering Undergraduate Honors Theses

Early detection of changes in epithelial cells, such as the development of neoplastic formations seen in epithelial dysplasia, can indicate regions of the epithelial tissue that are at a high risk for cancerous formation. Using concepts from diffuse reflectance spectroscopy, a Monte Carlo model was developed to predict the reflectance measured by a detector at a small source-detector separation on a microendoscope. The Monte Carlo results were then used to calculate a mathematical relationship between the reflectance and distance that can be used to determine optical properties in a tissue sample. This model was validated with liquid phantoms of specified …

Conceptualization And Fabrication Of A Bioinspired Mobile Robot Actuated By Shape Memory Alloy Springs, Lietsel Richardson

Electronic Theses and Dissertations

This work is an experimental study and fabrication of design concepts to validate the feasibility of smart materials and their applications in bio-inspired robotics. Shape-Memory Alloy (SMA) springs are selected as the smart material actuators of interest to achieve locomotion in the proposed mobile robot. Based on a previous design of the robot, this work focuses on both implementing a new locomotion concept and reducing size and weight of the previous design, both using SMA based actuators. Objectives are met in consideration of the conceptual mechanics of circular robot locomotion. The first prototype is a variation of the original design. …

Fluctuations In Walking Speeds And Spatiotemporal Gait Parameters When Walking On A Self-Paced Treadmill At Level, Incline, And Decline Slopes, Cesar Castano

Electronic Theses and Dissertations

On a daily basis, humans walk over a variety of terrains. Studies have shown that spatiotemporal gait parameters, such as stride length, stride frequency, stride variability, etc., change when humans walk down a decline and up an incline compared to level ground. However, these studies have been limited to using fixed speed treadmills or analyzing a small number of strides when conducted over ground. Thus, there is a need to investigate the fluctuations in spatiotemporal gait parameters of humans walking at their self-selected speed, which requires recording hundreds of strides. Here we hypothesized that subjects will walk with a slower …

Effects Of Ambient And Laser Light On Water Evaporation From The Surface Of Polyurethane Swabs Doped With Surfactant, Collin Campbell

Chemical Engineering Undergraduate Honors Theses

Polyurethane swabs are a common instrument for environmental sampling in the food, medical, and forensic fields due to their high recovery of organisms like viruses, spores, and bacteria. For sampling microbes in food and medical facilities, storage of the collected samples occurs under the absence of light to promote growth for more accurate testing. In the forensic fields, microbial growth results in sample contamination so the inhibition of this growth requires the drying of the swabs. This work studies the evaporation rates of water from polyurethane swabs under zero watt incident light, 30 W fluorescent bulb, 50 mW 532 nm …

Assessing Commonly Used Methods In Measuring Yield Of Cellulose Nanocrystals, Marilyn Pharr

Biological and Agricultural Engineering Undergraduate Honors Theses

Cellulose is a ubiquitous, renewable biopolymer found in plants that can be broken down to isolate cellulose nanocrystals (CNCs). CNCs have been utilized in various applications that include biomedical technology, structural composites, and barrier films because of their unique mechanical, optical, and physicochemical properties. CNCs can be produced by a variety of approaches from cellulosic materials; however, strong acid hydrolysis is the most common and effective technique as it results in stable colloidal suspensions. Existing literature reveals a wide range of CNC yields, depending on the production process, raw material used, and the method of yield estimation. The yields of …

Molecular Investigation Of The Intestinal Barrier In Health And Disease, Santita Ebangwese

Renée Crown University Honors Thesis Projects - All

The intestinal epithelial barrier contributes to the absorption of nutrients and in maintaining homeostasis. Several intestinal disorders such as Crohn’s disease and Ulcerative Colitis show common pathological features corresponding to a decreased intestinal epithelial barrier function, which makes it imperative to investigate the functional units of the intestinal barriers formed by complex protein interfaces called the tight junctions. Among the diverse set of transmembrane proteins involved in the formation of tight junctions, the mal-distribution of claudin family of proteins show direct correlation to compromised barrier functioning. Interestingly, claudin-3 expression reduces drastically in compromised barriers, while an increased expression of claudin-23 …

Predictive Modeling Of Fate And Transport Of Three Prevalent Contaminants In Midwest Agroecosystem Surface Waters: Nitrate-N, Atrazine, And Escherichia Coli, Samuel Hansen

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

The majority of streams and rivers in the United States (U.S.) are ecologically impaired, or threatened by anthropogenic stressors. Recent reports have found atrazine in drinking water to be associated with increased birth defects and incidences of Non-Hodgkin’s Lymphoma, with higher levels of significance from exposure to both atrazine and nitrate-N. In contrast, recent illnesses from E. coli contaminating vegetables that originated from irrigation water has increased awareness of identifying sources of E. coli entering irrigation reservoirs.

Methods to accurately predict atrazine and E. coli occurrence and potential sources in waterways continue to limit the identifying appropriate and effective prevention …

Methods To Remotely Eliminate Biofilm From Medical Implants Using 2.4 Ghz Microwaves, Brett Glenn

Mechanical Engineering Undergraduate Honors Theses

Infections associated with biofilm growth are usually challenging to eradicate due to their high tolerance toward antibiotics [11, 12]. Biofilms often form on the inert surfaces of medically implanted devices [13]. No matter the sophistication, microbial infections can develop on all medical devices and tissue engineering constructs [12]. Related infections lead to 2 million cases annually in the U.S., costing the healthcare system over $5 billion in additional healthcare expenses [12].

Novel solutions to biofilm’s microbial colonization span the spectrum of engineering and science disciplines. Yet a practical solution still does not exist. The research presented here will explore a …

3d Printing A Microfluidic Chip Capable Of Droplet Emulsion Using Ninjaflex Filament, Robert Andrews

Mechanical Engineering Undergraduate Honors Theses

This paper details an investigation into methods and designs of 3D printing a microfluidic system capable of droplet emulsion using NinjaFlex filament. The specific field in which this paper’s experiment is rooted is dubbed “BioMEMS,” short for bio microelectromechanical systems. One prominent research area in BioMEMS is developing a “lab on a chip.” Essentially, the goal is to miniaturize common lab processes to the micro scale, rendering it possible to include these processes in a small chip. Reducing necessary sample sizes, shortening the reaction times of lab processes, and increasing mobility of lab processes can all be realized through microfluidic …

Using Peripheral Venous Pressure Waveforms To Predict Key Hemodynamic Parameters, Ali Zohair A Alalawi

Graduate Theses and Dissertations

Analysis of peripheral venous pressure (PVP) waveforms is a novel method of monitoring intravascular volume. Two cohorts were used to study the hemodynamics change of the body state and its influence on the PVP using (1) dehydration setting with infants suffering from pyloric stenosis and (2) hemorrhage setting during a craniosynostosis elective surgery. The goal of this research is to develop a minimally invasive method of analyzing the PVP waveforms and find correlations with volume loss.

Twenty-three pyloric stenosis patients PVP were acquired at five stages and were divided into euvolemic, normal fluid volume, and hypovolemic, significant fluid loss. Seven …

Role Of Local Renin-Angiotensin System In Potentiating Early Calcific Aortic Valve Disease, Jessica Perez

Graduate Theses and Dissertations

Angiotensin-II (Ang-II), a peptide hormone, is a potent vasoconstrictor and cell mitogen. It has been implicated in the development of hypertension as well as atherosclerosis. Recent work has shown that sclerotic aortic valves possess expression of angiotensin type I receptor (AT-1R) and angiotensin converting enzyme (ACE), suggesting altered angiotensin signaling during disease. The role of altered angiotensin signaling on aortic valve mechanics, however, is not clearly understood. We seek to understand the direct effects of the renin angiotensin signaling (RAS) system on the biological and biomechanical properties of aortic valve tissue and develop a finite constitutive model that mimics the …

Bio-Desalination Of Brackish And Seawater Using Halophytic Algae, Endalkachew Sahle-Demessie, Ashraf Aly Hassan, Amro El Badawy

Department of Civil and Environmental Engineering: Faculty Publications

Global demand for water is rising. A sustainable and energy efficient approach is needed to desalinate brackish sources for agricultural and municipal water use. Genetic variation among two algae species, Scenedesmus species (S. sp.) and Chlorella vulgaris (C. vulgaris), in their tolerance and uptake of salt (NaCl) was examined for potential bio-desalination of brackish water. Salt-tolerant hyper-accumulators were evaluated in a batch photobioreactors over salinity concentration ranging from 2 g/L to 20 g/L and different nutrient composition for their growth rate and salt-uptake. During algae growth phase, the doubling time varied between 0.63 and 1.81 days for S …

Diffuse Reflectance Spectroscopy To Quantify In Vivo Tissue Optical Properties: Applications In Human Epithelium And Subcutaneous Murine Colon Cancer, Gage Joseph Greening

Graduate Theses and Dissertations

Colorectal cancer is the 4th most common and 2nd deadliest cancer. Problems exist with predicting which patients will respond best to certain therapy regimens. Diffuse reflectance spectroscopy has been suggested as a candidate to optically monitor a patient’s early response to therapy and has been received favorably in experimentally managing other cancers such as breast and skin. In this dissertation, two diffuse reflectance spectroscopy probes were designed: one with a combined high-resolution microendoscopy modality, and one that was optimized for acquiring data from subcutaneous murine tumors. For both probes, percent errors for estimating tissue optical properties (reduced scattering coefficient and …