Engineering Commons^™

Investigating The Role Of A Less Uranium Tolerant Strain, Isolated From The Hanford Site Soil, On Uranium Interaction In Polyphosphate Remediation Technology, Paola Sepulveda Medina

FIU Electronic Theses and Dissertations

Bacteria are key players in the processes that govern fate and transport of contaminants. Previous assessment showed that the Arthrobacter oxydans (A.oxydans) G968 strain has a lower ability to tolerate U(VI) toxicity in bicarbonate-free media compared to other isolate A.oxydans G975. The study experimentally investigated several parameters such as the potential of bicarbonate to accelerate U(VI) release from autunite mineral in the presence of a less U(VI) tolerant bacterial strain, in the conditions mimicking Hanford Site subsurface environments. Results showed that despite morphological differences between the two bacterial strains, A.oxydans G968 and G975, they are able to dissolute uranium at …

A Novel Signal Processing Method For Intraoperative Neurophysiological Monitoring In Spinal Surgeries, Krishnatej Vedala

FIU Electronic Theses and Dissertations

Intraoperative neurophysiologic monitoring is an integral part of spinal surgeries and involves the recording of somatosensory evoked potentials (SSEP). However, clinical application of IONM still requires anywhere between 200 to 2000 trials to obtain an SSEP signal, which is excessive and introduces a significant delay during surgery to detect a possible neurological damage. The aim of this study is to develop a means to obtain the SSEP using a much less, twelve number of recordings. The preliminary step involved was to distinguish the SSEP with the ongoing brain activity. We first establish that the brain activity is indeed quasi-stationary whereas …

Network Construction And Graph Theoretical Analysis Of Functional Language Networks In Pediatric Epilepsy, Anas Salah Eddin

FIU Electronic Theses and Dissertations

This dissertation introduces a new approach for assessing the effects of pediatric epilepsy on the language connectome. Two novel data-driven network construction approaches are presented. These methods rely on connecting different brain regions using either extent or intensity of language related activations as identified by independent component analysis of fMRI data. An auditory description decision task (ADDT) paradigm was used to activate the language network for 29 patients and 30 controls recruited from three major pediatric hospitals. Empirical evaluations illustrated that pediatric epilepsy can cause, or is associated with, a network efficiency reduction. Patients showed a propensity to inefficiently employ …

Real-Time Biosensor For The Assessment Of Nanotoxicity And Cancer Electrotherapy, Evangelia Hondroulis

FIU Electronic Theses and Dissertations

Knowledge of cell electronics has led to their integration to medicine either by physically interfacing electronic devices with biological systems or by using electronics for both detection and characterization of biological materials. In this dissertation, an electrical impedance sensor (EIS) was used to measure the electrode surface impedance changes from cell samples of human and environmental toxicity of nanoscale materials in 2D and 3D cell culture models. The impedimetric response of human lung fibroblasts and rainbow trout gill epithelial cells when exposed to various nanomaterials was tested to determine their kinetic effects towards the cells and to demonstrate the biosensor’s …

Bionano Electronics: Magneto-Electric Nanoparticles For Drug Delivery, Brain Stimulation And Imaging Applications, Rakesh Guduru

FIU Electronic Theses and Dissertations

Nanoparticles are often considered as efficient drug delivery vehicles for precisely dispensing the therapeutic payloads specifically to the diseased sites in the patient’s body, thereby minimizing the toxic side effects of the payloads on the healthy tissue. However, the fundamental physics that underlies the nanoparticles’ intrinsic interaction with the surrounding cells is inadequately elucidated. The ability of the nanoparticles to precisely control the release of its payloads externally (on-demand) without depending on the physiological conditions of the target sites has the potential to enable patient- and disease-specific nanomedicine, also known as Personalized NanoMedicine (PNM). In this dissertation, magneto-electric nanoparticles (MENs) …

Funtional Near Infrared Spectroscopy Study Of Language, Joint Attention And Motor Skills, Ujwal Chaudhary

FIU Electronic Theses and Dissertations

Near infrared spectroscopy (NIRS) is an emerging non-invasive optical neuro imaging technique that monitors the hemodynamic response to brain activation with ms-scale temporal resolution and sub-cm spatial resolution. The overall goal of my dissertation was to develop and apply NIRS towards investigation of neurological response to language, joint attention and planning and execution of motor skills in healthy adults. Language studies were performed to investigate the hemodynamic response, synchrony and dominance feature of the frontal and fronto-temporal cortex of healthy adults in response to language reception and expression. The mathematical model developed based on granger causality explicated the directional flow …

An Assessment Of Novel Biodegradable Magnesium Alloys For Endovascular Biomaterial Applications, Dharam Persaud-Sharma

FIU Electronic Theses and Dissertations

Magnesium alloys have been widely explored as potential biomaterials, but several limitations to using these materials have prevented their widespread use, such as uncontrollable degradation kinetics which alter their mechanical properties. In an attempt to further the applicability of magnesium and its alloys for biomedical purposes, two novel magnesium alloys Mg-Zn-Cu and Mg-Zn-Se were developed with the expectation of improving upon the unfavorable qualities shown by similar magnesium based materials that have previously been explored. The overall performance of these novel magnesium alloys has been assessesed in three distinct phases of research: 1) analysing the mechanical properties of the as-cast …

Electrochemical Immunosensing Of Cortisol In An Automated Microfluidic System Towards Point-Of-Care Applications, Abhay Vasudev

FIU Electronic Theses and Dissertations

This dissertation describes the development of a label-free, electrochemical immunosensing platform integrated into a low-cost microfluidic system for the sensitive, selective and accurate detection of cortisol, a steroid hormone co-related with many physiological disorders. Abnormal levels of cortisol is indicative of conditions such as Cushing’s syndrome, Addison’s disease, adrenal insufficiencies and more recently post-traumatic stress disorder (PTSD). Electrochemical detection of immuno-complex formation is utilized for the sensitive detection of Cortisol using Anti-Cortisol antibodies immobilized on sensing electrodes. Electrochemical detection techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) have been utilized for the characterization and sensing of the …

Multifunctional Nanoparticles In Cancer: In Vitro Characterization, In Vivo Distribution, Tingjun Lei

FIU Electronic Theses and Dissertations

A novel biocompatible and biodegradable polymer, termed poly(Glycerol malate co-dodecanedioate) (PGMD), was prepared by thermal condensation method and used for fabrication of nanoparticles (NPs). PGMD NPs were prepared using the single oil emulsion technique and loaded with an imaging/hyperthermia agent (IR820) and a chemotherapeutic agent (doxorubicin, DOX). The size of the void PGMD NPs, IR820-PGMD NPs and DOX-IR820-PGMD NPs were approximately 90 nm, 110 nm, and 125 nm respectively. An acidic environment (pH=5.0) induced higher DOX and IR820 release compared to pH=7.4. DOX release was also enhanced by exposure to laser, which increased the temperature to 42°C. Cytotoxicity of DOX-IR820-PGMD …

Effect Of Arginine And Oscillatory Ca2+ On Vascular Response Mediated Via Nitric Oxide Signaling In Normal And Salt Sensitive Hypertensive Rat Mesenteric Arterioles, Tushar V. Gadkari

FIU Electronic Theses and Dissertations

Hypertension, a major risk factor in the cardiovascular system, is characterized by an increase in the arterial blood pressure. High dietary sodium is linked to multiple cardiovascular disorders including hypertension. Salt sensitivity, a measure of how the blood pressure responds to salt intake is observed in more than 50% of the hypertension cases. Nitric Oxide (NO), as an endogenous vasodilator serves many important biological roles in the cardiovascular physiology including blood pressure regulation. The physiological concentrations for NO bioactivity are reported to be in 0-500 nM range. Notably, the vascular response to NO is highly regulated within a small concentration …

Modeling Of Loose Contamination Scenarios To Predict The Amount Of Contamination Removed, Duriem Calderin Morales

FIU Electronic Theses and Dissertations

The objective of this research is to evaluate the influence of the factors identified by the Johnson, Kendall and Robert’s theory that affect the strength of the detachment force necessary to remove a particle of contaminant from a surface, and the roughness of the surface in which the contaminant is present, on predicting the efficiency of removal of loose contamination. Two methods were used to reach this objective: the first method consisted of quantifying the contamination by weight and the second method of quantifying the contamination by counting alpha and gamma particles. As a result, it was determined that for …

Design And Development Of An Enzyme-Linked Biosensor For Detection And Quantification Of Phosphate Species, Serkan Akar

FIU Electronic Theses and Dissertations

The objective of this study is to design and development of an enzyme-linked biosensor for detection and quantification of phosphate species. Various concentrations of phosphate species were tested and completed for this study.

Phosphate is one of the vital nutrients for all living organisms. Phosphate compounds can be found in nature (e.g., water sediments), and they often exist in aninorganic form. The amount of phosphates in the environment strongly influences the operations of living organisms. Excess amount of phosphate in the environment causes eutrophication which in turn causes oxygen deficit for the other living organisms. Fish die and degradation of …

Biohazard Neutralization Based On Lipid Technology, Edelmira Bosques

FIU Electronic Theses and Dissertations

A rapid detection and neutralization method for biowarfare agents would be a great biodefense in war times. With this purpose, liposomes were developed following the lipid film formation, rehydration, and extrusion procedure as the production method. MgOCl2 was encapsulated in the liposomes and it was tested with three different bacterium B. cereus; B. thuringiensis; and B. subtilis. For specificity, the liposomes were modified with a polyclonal antibody against B. cereus and B. subtilis. The liposomes were characterized using a Malvern Zetasizer Instrument, and the study revealed stability of the liposomes stored at 4°C for a …

Development And Evaluation Of A Catheter Deliverable Artificial Aortic Heart Valve Prosthesis And Delivery System, Thomas Edward Claiborne Iii

FIU Electronic Theses and Dissertations

Currently, malfunctioning heart valves are replaced via highly invasive and costly open-heart procedures. A new alternative approach is a catheter deliverable or percutaneous heart valve. Current PHV prototypes utilize fixed animal tissue as valves. This research investigated the feasibility of an artificial PHV and the development of a delivery system. A left hea11 simulator and a tensile tester were used to characterize the hydrodynamics and mechanics of a novel artificial PHV. Test results showed equal or better in vitro hydrodynamic performance when compared to a St. Jude mechanical valve and an Edwards-Sapien PHV, with a mean pressure drop of <15 mmHg and a mean regurgitation of <5%. The PHV's exceeded requirements for fixation and radial force. The 24 F delivery system successfully delivered and deployed a PHV. The work described herein proves the feasibility of an artificial PHV and delivery system and justifies further investigation into its design and function.

A Robotic Ankle-Foot Orthosis With Integrated Electromyography Biofeedback Control For Improving Gait Symmetry In Stroke Rehabilitation, Szu-Min Chang

FIU Electronic Theses and Dissertations

The pathology of stroke attacks the central nervous system commonly resulting in the loss of voluntary neuromuscular control which negatively affects the walking capability of many survivors. New rehabilitation techniques utilizing biofeedback, robotic assisted movements, and gait specific exercises have been shown individually to increase the neurological recovery as compared to traditional methods of physical rehabilitation. The Biofeedback Assisted Robotic Ankle-foot orthosis (B.A.R.A.) is a prototype that combines all three characteristic treatments into a single portable device focused on improving voluntary dorsiflexion capability and gait patterns of the ankle-foot complex. The initial pilot study utilized a single healthy individual to …

Detection And Neutralization Of Bacterial Biohazards Via Nanoencapsulation, Rosaura De Zayas

FIU Electronic Theses and Dissertations

Bacteria biohazards, such as Anthrax, are responsible for causing mild to serious illnesses in humans and animals. The primary aim of this research study was to develop a rapid one step assay to detect and neutralize bacteria-based biohazards, using an Immunoliposome-nanoparticle complex. An Anthrax model, Bacillus cereus, was grown for 3 hours and diluted 1:25 in media (2.0 x 107 cfu/ml). The Bacillus cereus was interacted with an Immunoliposome-nanoparticle complex containing an MgO-C 2 neutralization agent. The samples were analyzed via flow cytometry with a 1:8:1 ratio Bacillus cereus, Immunoliposome-nanoparticle complex, and Ethidium homodimer-1 for two hours. The results obtained …

Vascular Reactivity Of Isolated Rat Mesenteric Arterioles In The Presence And Absence Of Ouabain, Rohit Chawla

FIU Electronic Theses and Dissertations

The microvasculature plays a significant role in the regulation of blood pressure and regional blood supply. Cardiotonic steroids like the adrenal cortical hormone (ouabain) have been proposed to play a role in some forms of hypertension. The purpose of this study was to determine the effect of different agonists on arteriolar diameter in the presence and absence of ouabain.

In Vitro studies on isolated intact rat mesenteric arterioles were performed by administering different concentrations of the vasoconstrictor norepinephrine (NE) and the vasorelaxant acetylcholine (Ach) in the presence and absence of ouabain. NE induced constriction was not significantly enhanced in the …

Effect Of Blood Flow Patterns On Localized Platelet Adhesion Under Physiologic Flow Conditions Using Two-Dimensional And Three-Dimensional Stent Models - An Experimental And Computational Approach, Nandini Duraiswamy

FIU Electronic Theses and Dissertations

This dissertation presents dynamic flow experiments with fluorescently labeled platelets to allow for spatial observation of wall attachrent in inter-strut spacings, to investigate their relationship to flow patterns. Human blood with fluorescently labeled platelets was circulated through an in vitro system that produced physiologic pulsatile flow in (1) a parallel plate flow chamber that contained two-dimensional (2D) stents that feature completely recirculating flow, partially recirculating flow, and completely reattached flow, and (2) a three-dimensional (3D) cylindrical tube that contained stents of various geometric designs.

Flow detachment and reattachment points exhibited very low platelet deposition. Platelet deposition was very low in …

Characterization Of Cerebral Blood Flow Response To Traumatic Brain Injury In An Animal Model Using Spect., Michael Capille

FIU Electronic Theses and Dissertations

In this study the focal effects of moderate traumatic brain injury (TBI) on cerebral blood flow (CBF) as reported by SPECT cerebral brain perfusion (CBP) imaging in an animal model were investigated by parallelized statistical techniques. Subjects were randomly assigned to either a control group or test group receiving fluid percussion injury directly to the left parietal lobe.

Qualitative SPECT CBP accuracy was assessed against reference radioactive microsphere technique (RMT) regional CBF measurements by map reconstruction, registration and smoothing. Cerebral hypoperfusion in the test group was then identified at the voxel level using a statistical parametric mapping (SPM) model.

Using …

Modification Of A Novel Polymer With Potential Use In Artificial Heart Valves : Effects On Hemocompatibility And Mechanical Properties, Tejas Dilipkumar Choksi

FIU Electronic Theses and Dissertations

Platelet mediated thrombosis has been a major source of mortality and morbidity in cardiovascular device patients as the device surface upon contact with blood induces surface thrombosis. Two specific objectives of this thesis are: 1) Identify the effect of phospholipid modification on Quatromer and 2) Identify the most effective modification technique that will inhibit the surface induced thrombosis and enhance the long-term blood compatibility of Quatromer. Six different phospholipids were grafted in the Quatromer and the role of each of the modified substrates was evaluated in terms of mechanical properties and hemocompatibility. The surface analysis studies showed a significant decrease …

A Computational Method For Internal Radiation Dosimetry At The Voxel Level, Swapna Chigurupati

FIU Electronic Theses and Dissertations

The current development of hybrid SPECT/CT and PET/CT systems allows not only accurate attenuation correction of images, but also provide an anatomical frame for the 3D spatial representation of the dose distribution. The main goal of this thesis project was to develop computational algorithms for calculation of the 3D dose distribution delivered by internal emitters based on the images and information provided by new hybrid SPECT/CT and PET/CT systems. Although many experimental problems exist in patient-specific dosimetry, current drawback is the lack of radionuclide voxel S values for the set of all possible combinations of cubical and non-cubical pixel edges …

Accuracy Of Activity Quantitation Of F-18 Fluorodeoxyglucose (Fdg) Positron Emission Tomography (Pet) Imaging Using Simulated Malignant Tumors, Madhu Durai

FIU Electronic Theses and Dissertations

This thesis involves a procedure, which calculated and compared the sum of all the pixel counts, threshold pixel counts sum of a 3D PET image and mean and maximum pixel count of one single transaxial slice (2D) of simulated tumors for a chosen region of interest (ROI). A calibration factor was multiplied by the sum of the pixel counts, threshold pixel counts sum of all the transaxial slices, and the mean, and maximum pixel counts of one single transaxial slice in an ROI to calculate for the activity of the tumor. This activity calculated was compared with the real activity …

A Dosimetry And Radiobiological Model For Intravascular Brachytherapy Treatment Planning With Radioisotope Emitting Stents, Maria Alejandra Caceres

FIU Electronic Theses and Dissertations

The aim of this study was to develop a practical, versatile and fast dosimetry and radiobiological model for calculation of the 3D dose distribution and radiobiological effectiveness of radioactive stents. The algorithm was written in Matlab 6.5 programming language and is based on the dose point kernel convolution. The dosimetry and radiobiological model was applied for evaluation of the 3D dose distribution of ³²P, ⁹⁰Y, ¹⁸⁸Re and ¹⁷⁷Lu stents. Of the four, ³²P delivers the highest dose, while ⁹⁰Y, ¹⁸⁸Re and ¹⁷⁷Lu require high levels of activity to deliver a significant therapeutic …

Static And Dynamic Mechanical Testing Of A Polymer With Potential Use As Heart Valve Material, Andres Felipe Aguirre

FIU Electronic Theses and Dissertations

Synthetic tri-leaflet heart valves generally fail in the long-term use (more than 10 years). Tearing and calcification of the leaflets usually cause failure of these valves as a consequence of high tensile and bending stresses borne on the material. The primary purpose of this study was to explore the possibilities of a new polymer composite to be used as synthetic tri-leaflet heart valve material. This composite was comprised of polystyrene-polyisobutylene-polystyrene (Quatromer), a proprietary polymer, embedded with continuous polypropylene (PP) fibers. Quatromer had been found to be less likely to degrade in vivo than polyurethane. Moreover, it was postulated that a …

Characterization Of Engineered Human Lung Tissue, Benjamin Boytor

FIU Electronic Theses and Dissertations

Characterizing engineered human lung tissue is an important step in developing a functional tissue replacement for lung tissue repair and in vitro analysis. Small tissue constructs were grown by seeding IMR-90 fetal lung fibroblasts and adult microvascular endothelial cells onto a Polyglycolic acid (PGA) polymer template. Introducing the constructs to dynamic culture conditions inside a bioreactor facilitated three-dimensional growth seen in scanning electron microscopy images (SEM).

Characterization of the resultant tissue samples was done using SEM imagery, tensile tests, and biochemical assays to quantify extra-cellular matrix (ECM) composition. Tensile tests of the engineered samples indicated an increase in the mechanical …