Biomedical Engineering and Bioengineering Commons^™

In Vitro Validation Of Finite Element Analysis Of Blood Flow In Deformable Models, Ethan Kung, Andrea S. Les, C. Alberto Figueroa, Francisco Medina, Karina Arcaute, Ryan B. Wicker, Michael V. Mcconnell, Charles A. Taylor

Publications

The purpose of this article is to validate numerical simulations of flow and pressure incorporating deformable walls using in vitro flow phantoms under physiological flow and pressure conditions. We constructed two deformable flow phantoms mimicking a normal and a restricted thoracic aorta, and used a Windkessel model at the outlet boundary. We acquired flow and pressure data in the phantom while it operated under physiological conditions. Next, in silico numerical simulations were performed, and velocities, flows, and pressures in the in silico simulations were compared to those measured in the in vitro phantoms. The experimental measurements and simulated results of …

A Study Of Osteocyte Apoptosis By Region And Quadrant In Murine Cortical Bone, Jessica Kristen Chan

Master's Theses

ABSTRACT

A Study of Osteocyte Apoptosis by Region and Quadrant in Murine Cortical Bone

Jessica Kristen Chan

Osteocytes undergo apoptosis to spatially and temporally initiate bone remodeling.  This study investigates the distribution of apoptotic osteocytes within different quadrants and regions of cortical bone and compares the frequency of osteocyte apoptosis to regional factors associated with bone remodeling.  Specifically, the quantity of apoptosis was compared to levels of the bone morphagenic protein antagonists noggin and gremlin.  Samples of unloaded right tibial bone obtained from C57/Bl/6 mice underwent TUNEL staining for apoptotic osteocytes and were counterstained with methyl green to detect osteocyte …

Universal Engineering Programmer – An In-House Development Tool For Developing And Testing Implantable Medical Devices In St. Jude Medical, Khoa Tat Do

Master's Theses

During development and testing of the functionality of the pacemaker and defibrillator device, engineers in the St. Jude Medical Cardiac Rhythm Management Division use an in-house development tool called Universal Engineering Programmer (UEP) to ensure the device functions as expected, before it can be used to test on an animal or a human during the implantation process.  In addition, some applications of UEP are incorporated into the official releases of the device product.  UEP has been developed and used by engineers across departments in the St. Jude Medical Cardiac Rhythm Management Division (CRMD).  This thesis covers the flexible and reusable …

The Biomechanics Of Varied Proximal Locking Screw Configurations In A Synthetic Model Of Proximal Third Tibial Fracture Fixation, Philip R. Wolinsky, Douglas Dennis, Brett D. Crist, Shane Curtiss, Scott J. Hazelwood

Biomedical Engineering

Objective: To determine if 1) angularly stable devices created by compressing (‘‘locking’’) proximal locking screws to intramedullary nails using end caps or compression screws or 2) increasing the number of proximal screws from two to three increases the stiffness of intramedullary constructs that stabilize proximal third tibia fractures in a nonosteopenic bone model.

Methods: Four proximal locking screw configurations were examined in a synthetic composite tibia model with a 2-cm gap simulating a comminuted proximal third tibia fracture with no bony contact: 1) two proximal screws not compressed to the nail; 2) one of two proximal screws compressed to …

A Novel Pulsed Corona Discharge Reactor Based On Surface Streamers For No Conversion From N2-O2 Mixture Gases, M. A. Malik, Karl H. Schoenbach

Bioelectrics Publications

A novel pulsed corona discharge reactor is described which utilizes surface-plasma along insulating surfaces. The electrodes are comprised of a stainless steel wire anode of 150 µm diameter stretched along the surface of a glass sheet and two parallel aluminum strips as cathodes. An eight-stage Marx bank, which provides 60 ns, 40-45 kV monopolar pulses, was used to produce the surface streamers in nitrogen-oxygen mixtures at atmospheric pressure. With increasing oxygen content, the energy efficiency for NO2 and O3 synthesis was found to increase. The energy efficiency is almost the same for the surface-plasma and volume-plasma. However, the surface-plasma was …

Synthesis Of Latex Based Antibacterial Acrylate Polymer/Nanosilver Via In Situ Miniemulsion Polymerization, Mostafa Yazdi Mamaghani, Malihe Pishvaei, Babak Kaffashi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Silver nanoparticles were incorporated into poly-{methyl methacrylate-butyl acrylate-acrylic acid} using two different approaches. The first approach was based on dispersing the nano silver particles in acrylic latex (previously synthesized by the emulsion polymerization) and the second is the in-situ polymerization of acrylate monomers in the presence of silver nanoparticles by Mini emulsion polymerization. Mini emulsion polymerization can yield a better dispersion of nano silver in the polymeric particles because organic particles can be dispersed directly in the monomer droplets becoming encapsulated upon polymerization. Morphological investigations were performed using SEM and TEM. FTIR and thermal analyses revealed the silver nanoparticles to …

Radio-Frequency Breast Cancer Imaging Results For A Simplified Cylindrical Phantom, Giuseppe Ruvio, Raffaele Solimene, Antonietta D'Alterio, Max Ammann, Rocco Pierri

Conference Papers

Microwave imaging is a pervasive research field and
is useful in numerous applicative diagnostic noninvasive contexts. This paper focuses on two aspects. First, we perform a numerical investigation to assess the role played by fundamental parameters (i.e. number of sensors, operating frequency bandwidth) on cancer detection. To this end, a simplified cylindrical phantom probed by ideal two-dimensional dipoles (i.e. infinitely long along the axis of invariance) is considered. Second, in order to focus on the role of the antennas, we analyze, still by numerical simulations and for a simplified breast model, how performances vary when a realistic antenna is adopted.

Micro-Ct Characterization Of Human Trabecular Bone In Osteogenesis Imperfecta, John Jameson, Carolyne Albert, Peter Smith, Robert C. Molthen, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Osteogenesis imperfecta (OI) is a genetic syndrome affecting collagen synthesis and assembly. Its symptoms vary widely but commonly include bone fragility, reduced stature, and bone deformity. Because of the small size and paucity of human specimens, there is a lack of biomechanical data for OI bone. Most literature has focused on histomorphometric analyses, which rely on assumptions to extrapolate 3-D properties. In this study, a micro-computed tomography (μCT) system was used to directly measure structural and mineral properties in pediatric OI bone collected during routine surgical procedures. Surface renderings suggested a poorly organized, plate-like orientation. Patients with a history of …

In Vitro Validation Of Finite-Element Model Of Aaa Hemodynamics Incorporating Realistic Outlet Boundary Conditions, Ethan Kung, Andrea S. Les, Francisco Medina, Ryan B. Wicker, Michael V. Mcconnell, Charles A. Taylor

Publications

The purpose of this study is to validate numerical simulations of flow and pressure in an abdominal aortic aneurysm (AAA) using phase-contrast magnetic resonance imaging (PCMRI) and an in vitro phantom under physiological flow and pressure conditions. We constructed a two-outlet physical flow phantom based on patient imaging data of an AAA and developed a physical Windkessel model to use as outlet boundary conditions. We then acquired PCMRI data in the phantom while it operated under conditions mimicking a resting and a light exercise physiological state. Next, we performed in silico numerical simulations and compared experimentally measured velocities, flows, and …

Bacterial Killing By Dry Metallic Copper Surfaces, Christophe Espírito Santo, Ee Wen Lam, Christian Elowsky, Davide Quaranta, Dylan W. Domaille, Christopher J. Chang, Gregor Grass

Nebraska Center for Biotechnology: Faculty and Staff Publications

Metallic copper surfaces rapidly and efficiently kill bacteria. Cells exposed to copper surfaces accumulated large amounts of copper ions, and this copper uptake was faster from dry copper than from moist copper. Cells suffered extensive membrane damage within minutes of exposure to dry copper. Further, cells removed from copper showed loss of cell integrity. Acute contact with metallic copper surfaces did not result in increased mutation rates or DNA lesions. These findings are important first steps for revealing the molecular sensitive targets in cells lethally challenged by exposure to copper surfaces and provide a scientific explanation for the use of …

Laser Etched Pmma Microfluidic Chip Design And Manufacture With Applications In Capillary Zone Electrophoresis, Evan Allen Barbre

Master's Theses

This thesis encompasses a feasibility study of using low-cost materials to manufacture microfluidic chips that can perform the same functions as chips manufactured using traditional methods within an acceptable range of efficiency of chips created with more exotic methods and materials. The major parts of the project are the selection and characterization of the fabrication methods for creating the channels for fluid flow, the methods for sealing the channels to create a usable chip and the electrophoretic separations of carboxylated microspheres of different potentials. In this work we seek to answer the question if laser-etched PMMA microfluidic chips are comparable …

Race- And Sex-Related Differences In Retinal Thickness And Foveal Pit Morphology, Melissa Wagner-Schuman, Adam M. Dubis, Rick Nordgren, Yuming Lei, Daniel Odell, Hellen Chiao, Eric Weh, William Fischer, Yusufu N. Sulai, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose.

To examine sex- and race-associated differences in macular thickness and foveal pit morphology by using spectral-domain optical coherence tomography (SD-OCT).

Methods.

One hundred eighty eyes of 90 healthy patients (43 women, 47 men) underwent retinal imaging with spectral-domain OCT. The lateral scale of each macular volume scan was corrected for individual differences in axial length by ocular biometry. From these corrected volumes, Early Treatment Diabetic Retinopathy Study (ETDRS) grids of retinal thickness were generated and compared between the groups. Foveal morphology was measured with previously described algorithms.

Results.

Compared with the Caucasians, the Africans and African Americans had reduced …

Electroporation-Induced Electrosensitization, Olga N. Pakhomova, Betsy W. Gregory, Vera A. Khorokhorina, Anglela M. Bowman, Shu Xiao, Andrei G. Pakhomov

Bioelectrics Publications

BACKGROUND: Electroporation is a method of disrupting the integrity of cell membrane by electric pulses (EPs). Electrical modeling is widely employed to explain and study electroporation, but even most advanced models show limited predictive power. No studies have accounted for the biological consequences of electroporation as a factor that alters the cell's susceptibility to forthcoming EPs.

METHODOLOGY/PRINCIPAL FINDINGS: We focused first on the role of EP rate for membrane permeabilization and lethal effects in mammalian cells. The rate was varied from 0.001 to 2,000 Hz while keeping other parameters constant (2 to 3,750 pulses of 60-ns to 9-micros duration, 1.8 …

Sar Map Of Gel Phantom In A 64mhz Mri Birdcage By Fiber-Optic Thermometry And Fdtd Simulation, Chirag Mukesh Patel

Master's Theses

As implantable medical devices are being used more often to treat medical problems for which pharmaceuticals don’t suffice, it is important to understand their interactions with commonly used medical modalities. The interactions between medical implants and Magnetic Resonance Imaging machines have proven to be a risk for patients with implants.

Implanted medical devices with elongated metallic components can create harmful levels of local heating in a Magnetic Resonance Imaging (MRI) environment [1]. The heating of a biological medium under MRI is monitored via the Specific Absorption Rate (SAR). SAR, defined as power absorbed per unit mass (W/kg), can be calculated …

The Structural Role Of Titanium In Ca-Sr-Zn-Si/Ti Glasses For Medical Applications, A. W. Wren, F. R. Laffir, A. Kidari, Mark R. Towler

Chemical and Biochemical Engineering Faculty Research & Creative Works

Glasses for medical applications are used in particulate form or as a cement component. This work was undertaken to determine structural changes in 0.48SiO₂-0.36ZnO-0.12CaO-0.04SrO glass when the SiO₂ is substituted with 5 mol% increments of TiO2. X-ray Diffraction (XRD) was used to determine the presence of crystallinity. This occurred after additions of 20 mol% TiO₂. Differential Thermal Analysis (DTA) and Network connectivity (NC) calculations determined that by increasing the TiO₂ content, the T_g and NC reduced (T_g 670 °C to 632 °C, NC 1.83 to -1.14) suggesting that TiO₂ acts as …

Investigation Of Pmma Cement Penetration In Prepared Femoral Heads With A Longitudinal Slot For Hip Resurfacing Arthroplasty, Scott Snyder

Biomedical Engineering

Hip resurfacing arthroplasty is becoming increasingly popular in younger, active patients due to its preservation of natural biomechanics. Failure of these implants can be very traumatic and potentially life threatening. The role of cement penetration in early implant failure is not yet known, and must be investigated. This study specifically investigates the effects of a 5mm by 5mm longitudinal channel on cement penetration into the femoral head. High-density open-cell reticulated vitreous carbon foam cylinders and Huntsman Pro-cast® 20 implants based on the Birmingham Hip Resurfacing implant were used. It was determined cement penetration was increased in the area immediately surrounding …

Modeling Of Equilibrium Point Trajectory Control In Human Arm Movements, Kai Chen

Dissertations

The underlying concept of the Equilibrium Point Hypothesis (EPH) is that the CNS provides a virtual trajectory of joint motion, representing spacing and timing, with actual movement dynamics being produced by interactions of limb inertia, muscle viscosity and speed/position feedback from muscle spindles. To counter criticisms of the EPH, investigators have proposed the use of complex virtual trajectories, non-linear damping, stiffness and time varying stiffness to the EPH model. While these features allow the EPH to adequately produce human joint velocities, they conflict with the EPH’s premise of simple pre-planned monotonic control of movement trajectory. As a result, this study …

Development Of A Centrifugal Microfluidic Device For Separation And Sorting In Biological Fluids, Gaurav Sunil Bagwe

Theses

A wide interest in employing micron-scale, integrated biochemical analysis systems for economical and rapid diagnosis has been the principal motivation behind this project. Low operating costs, portability and fast diagnosis times make centrifugal microfluidic devices an attractive option in patient-side diagnostics. Some essential tasks to be performed in microfluidic devices are sample-reagent transport, mixing, separation and detection. All these tasks require precise control of the RPM and spinning time. Centrifugal micro-fluidic platforms have been successfully implemented for detection of hepatitis A, tetanus, as well as for measurement of haemoglobin and hematocrit, for DNA analysis, and for assessment of cardiac disease …

Emg-Based Determination Of Upper Extremity Virtual Trajectory, Akshata Anand Korgaonkar

Theses

Movement and position of the limbs of the human body are controlled by the interaction between the muscle and the peripheral and central nervous system. This interaction is nothing but the neural signals. Neural signals are electrical in nature and referred as action potentials. An EMG is a summation of action potentials from the muscle fibers under the electrode placed on the skin. Thus it is easy to estimate the nature and timing of the movement from the firing of an EMG signal. Kai Chen in his dissertation has built the model to represent the arm movement with stiffness, damping, …

Motor Planning For Reach Memorization Task In 3d Space, Atul Narkhede

Theses

Arm reaching towards remembered targets in three-dimensional space was analyzed. The aim of the project was to test whether various amounts of visual feedback, in combination with constant forces applied to the arm during reaching would affect the magnitude and direction of the reaching errors. The robotic arm (Haptic Master, Moog Inc) recorded the spatial position of the pointer attached to its end effector, thus tracking the movement of the subject's arm. Three haptically rendered targets at different points in space were presented to the subjects using stereo virtual environment. The simulation was programmed using Visual C++ and OpenGL. Eight …