Biomedical Engineering and Bioengineering Commons^™

Quantitative Reappraisal Of The Helmholtz-Guyton Resonance Theory Of Frequency Tuning In The Cochlea, Charles F. Babbs

Weldon School of Biomedical Engineering Faculty Publications

To explore the fundamental biomechanics of sound frequency transduction in the cochlea, a two-dimensional analytical model of the basilar membrane was constructed from first principles. Quantitative analysis showed that axial forces along the membrane are negligible, condensing the problem to a set of ordered one-dimensional models in the radial dimension, for which all parameters can be specified from experimental data. Solutions of the radial models for asymmetrical boundary conditions produce realistic deformation patterns. The resulting second-order differential equations, based on the original concepts of Helmholtz and Guyton, and including viscoelastic restoring forces, predict a frequency map and amplitudes of deflections …

Manipulating Cellular Growth Responses To Patterning, Apoptotic, And Environmental Cues, James N. Mcnamara

Doctoral Dissertations

In this work, various methods of controlling cell growth are examined. Cell-cell interaction, apoptotic cues, three dimensional scaffolds, and non-adherent environments are evaluated for their ability to affect the differentiation, morphology, and growth rate of different cell types. Previous work has shown that cell growth and cell morphology can be influenced by patterns of polymers coated on surfaces in two dimensions, designated here as the x and y dimensions of a standard Cartesian coordinate system. Tissue engineering and regenerative medicine studies have shown limited success in modifying growth in the third, z dimension. This work considers not only the x, …

Ultrasonic Assisted Layer-By-Layer Assembly For Stable Nanocolloids Of Curcumin And Paclitaxel, Zhiguo Zheng

Doctoral Dissertations

Researchers have been trying to fight cancer with synthesis of new bioactive compounds but many of these novel drugs have low solubility in water and it is difficult to deliver them into a patient's body. One way of solving this particular problem is to use nanoscale drug delivery systems. In this dissertation, we describe using an ultrasonic assisted layer-by-layer encapsulation process to prepare anti-cancer drugs with 50∼200 nm particle size with designed coating to achieve sustained release and target delivery.

Two methods for systematic manufacture of low solubility anti-cancer drug nanoparticles were proposed: I) Top-down approach to breakdown larger drug …

The Effect Of Maternal Diet On Fetal Development, Catherine Wilcox

Renée Crown University Honors Thesis Projects - All

Using mice as a model system, this study aimed to compare the effect of a high fat diet (HFD), high sugar diet (HSD) and a control diet (CD) on fetal growth and development at the time of birth (post-natal day 0 or PND 0), post-natal day 7 (PND 7) and post-natal day 14 (PND 14). Published literature has documented the effects of a negative in-utero environment on fetal development, but currently there is limited research regarding the continued effects on development after birth. Mouse pups were harvested and then imaged in 3-D using a high-resolution micro-computed tomography (micro-CT) system. Total …

Section Abstracts: Biomedical And General Engineering

Virginia Journal of Science

Abstracts of the Biomedical and General Engineering Section for the 89th Annual Meeting of the Virginia Academy of Science, May 25-27, 2011, University of Richmond, Richmond VA.

The Dominant Role Of The Hip In Multijoint Reflex Responses In Human Spinal Cord Injury, Tanya Onushko

Dissertations (1934 -)

Following a spinal cord injury (SCI), people often experience exaggerated reflexes, such that mild provocations can cause prolonged and uncontrolled muscle activity throughout the entire leg. These reflexes can be problematic and are known to interfere with functional tasks, such as transferring to and from a wheelchair, and they may interfere with locomotor function by prolonging muscle activity and/or inappropriately activating muscles during attempts to walk. While these multijoint reflexes have been shown to originate from several afferent cues, hip afferent input is a particularly potent sensory signal that readily triggers multijoint reflexes. The overall objective of this dissertation was …

Design And Development Of Two Test Fixtures To Test The Longitudinal And Transverse Tensile Properties Of Small Diameter Tubular Polymers, Carolyn Berry

Master's Theses

Hundreds of thousands of vascular bypass grafts are implanted in the United States every year, but there has yet to be an ideal graft material to substitute for one’s own autologous vessel. Many synthetic materials have been shown to be successful vessel replacements; however, none have been proven to exhibit the same mechanical properties as native vessels, one of the most important criteria in selecting a vascular graft material. Part of this issue is due to the fact that, currently, there is no “gold standard” for testing the longitudinal and transverse tensile properties of small diameter tubular materials. While there …

Leaching Of Potential Hazardous Elements Of Coal Cleaning Rejects, Luis F.O. Silva, Maria Izquierdo, Xavier Querol, Robert B. Finkelman, Marcos L.S. Oliveira, Marcus Wollenschlager, Mark R. Towler, Rafael Pérez-López, Felipe Macias

Chemical and Biochemical Engineering Faculty Research & Creative Works

The geochemical characteristics of coal cleaning rejects (CCR) in Santa Catarina State, Brazil, were investigated. Around 3.5 million ton/ year of coal waste are dumped in Santa Catarina State. Coal beneficiation by froth flotation results in large amounts of CCR composed of coaly and mineral matter, the latter characterized by the occurrence of sulphide minerals and a broad array of leachable elements. The total and leachable contents of more than 60 elements were analyzed. Atmospheric exposure promotes sulphide oxidation that releases substantial sulphate loads as well as Ca²⁺, K⁺, Mg²⁺, Cl- and Al^{3+ …}

Evaluation Of A Novel Non-Penetrating Electrode For Use In Dna Vaccination, Amy Donate, Domenico Coppola, Yolmari Cruz, Richard Heller

Bioelectrics Publications

Current progress in the development of vaccines has decreased the incidence of fatal and non-fatal infections and increased longevity. However, new technologies need to be developed to combat an emerging generation of infectious diseases. DNA vaccination has been demonstrated to have great potential for use with a wide variety of diseases. Alone, this technology does not generate a significant immune response for vaccination, but combined with delivery by electroporation (EP), can enhance plasmid expression and immunity. Most EP systems, while effective, can be invasive and painful making them less desirable for use in vaccination. Our lab recently developed a non-invasive …

Learning Feature Dependencies For Noise Correction In Biomedical Prediction, Ghim-Eng Yap, Ah-Hwee Tan, Hwee Hwa Pang

Research Collection School Of Computing and Information Systems

The presence of noise or errors in the stated feature values of biomedical data can lead to incorrect prediction. We introduce a Bayesian Network-based Noise Correction framework named BN-NC. After data preprocessing, a Bayesian Network (BN) is learned to capture the feature dependencies. Using the BN to predict each feature in turn, BN-NC estimates a feature's error rate as the deviation between its predicted and stated values in the training data, and allocates the appropriate uncertainty to its subsequent findings during prediction. BN-NC automatically generates a probabilistic rule to explain BN prediction on the class variable using the feature values …

Ultrasonic And Stereo-Optical Characterization Techniques For Applications In Mechanical Testing, Jonathan M. Hein

Department of Engineering Mechanics: Dissertations, Theses, and Student Research

This thesis considers methods developed based on ultrasonic reflections from interfaces and stereo-optical surface strain measurements to study the mechanical characterization of materials and bodies. The ultrasonic method is used to characterize wave speed and attenuation for highly attenuating samples. The stereo-optical strain measurements are used to characterize the effects of genes on mechanical properties of bone, and the dynamic characterization of blast waves in the UNL Shock Wave Trauma Mechanics facility.

A method is described and developed for characterizing the wave speed and attenuation spectrums from reflected waves from the contact surface with an unknown material. The method is …

Life Cycle Assessment Of Greenhouse Gas Emissions From Ethanol And Biopolymers, Adam J. Liska, Xiao Xue Fang

Adam Liska Papers

Conclusions

• Regulatory LCA is not likely to be used for non‐fuel chemicals alone in the near future

• Significant GHG emission credits for corn‐ethanol can be obtained by using only roughly 6‐9% of initial starch for production of biopolymers based on previous LCA theory

• Pay close attention to values in calculating credits per kg—these have to stand up in litigation to ensure the credit

• Credits are proportional to the mass of polymer produced

• Many theoretical issues are uncertain and credits will only be determined in conjunction with EPA

• Indirect emissions are uncertain and are a …

Bitten By The Science Bug (Nycsef 2011), Maribel Vazquez

Publications and Research

The invited keynote address to the participants of the final round of the 2011 New York City Science and Engineering Fair (NYCSeF) at the American Museum of Natural History (AMNH).

Polymeric Splint And Rapid-Setting Polyurethane, Lanny Griffin, Dane Robert Jones

Biomedical Engineering

A splint includes a first container capable of being wrapped about an item to be supported and a second container capable of containing a multiple part mixture during a mixing operation. The second container being capable of delivering the mixture into the first container, wherein the mixture hardens to form a support structure. A method for using the splint is also disclosed.

Department Of Biological Systems Engineering Newsletter, Volume 7, Number 1, March 2011

BSE Department Magazine

No abstract provided.

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 …