Cord Blood Endothelial Progenitor Cell Adhesion to Fibronectin Under Laminar Shear
Supervising Professor: Dr. George Truskey, Professor and Chair of Biomedical Engineering
Mathew is a senior Biomedical Engineering and Chemistry double major studying cord blood
endothelial progenitor cell (CB-EPC) adhesion to biological substrates and their
characterization. Atherosclerosis is the leading cause of death in the industrialized
world. Therapeutic treatments, such as balloon angioplasty, result in further blood
vessel damage. Previously, we have characterized CB-EPCs for their potential to
reendothelialize denuded vessels in vitro and to serve as a promising source for synthetic
vascular grafts and tissue-engineered blood vessels. We determined that CB-EPCs are a
superior cell source relative to human aortic endothelial cells as CB-EPCs are easily
attainable, posses a high proliferative potential, exhibit high EC-specific markers, have
strong adhesion to the underlying substrate at supraphysiological shear stress, and
inhibit neointimal hyperplasia. Currently, the adhesion mechanisms of CB-EPCs have yet
to be investigated. The main goal of the current work is to determine the major factors
of CB-EPC adhesion to fibronectin, an extracellular matrix protein where EC integrins
bind. It has been found that cell adhesion is dependent on ligand concentration, force on
cells, and contact area. Adhesion increased as shear stress increased, with a maximum at
1.0 dyn/cm2. There has been no physical explanation to support the increase in adherent
cells. Future work includes RT-PCR analyses as well as immunofluorescence studies of
target proteins involved in focal adhesions.
Mathew will be applying to MD/PhD programs upon graduation and is hoping to continue
his research after Duke.
Pediatric Crash Test Dummy Development: Investigation of the Mechanical
and Constitutive Properties of the Neurocentral Synchondrosis
Supervising Professor: Dr. Roger Nightingale, Biomedical Engineering
Pediatric neck injury is a catastrophic and preventable injury, yet there has been inadequate research into the mechanics of these injuries. This research is intended to provide insight into the constitutive and mechanical properties of the pediatric neck, specifically the neurocentral synchondroses. The neurocentral synchondroses are a cartilaginous material present in the pediatric spine, and they are a contributor to vertebral mechanics. The constitutive properties of these synchondroses can be determined using a finite element model. Bone-synchondrosis-bone complexes have been scanned using a MicroCT to produce high-resolution image sets which can be analyzed using Amira (Visage Imaging, Carlsbad, CA), a 3-D imaging software package. The computed tomography (CT) data can be imported into Hypermesh (Altair, Troy, MI), a finite element analysis program, to create a 3-D meshed model. From this 3-D meshed model a test battery can be simulated using LS-DYNA (LSTC, Livermore, CA), and viscoelastic properties can be found and compared against an experimental test battery in order to validate the model using LS-Opt (LSTC, Livermore, CA). So far, the finite element model template has been designed, and the viscoelastic battery is being developed. The next step is to incorporate the geometry from the MicroCT scans and optimize viscoelastic parameters using a tandem of LS-DYNA, LS-Opt, and experimental data.
Brian will be attending medical school after graduating from Duke.
Design, Fabrication and Testing of Nonvolatile Tunable Metamaterials
Supervising Professor: Dr. Steven Cummer, Electrical and Computer Engineering
John Barrett is a senior Pratt Fellow in the Electrical and Computer Engineering researching materials with a negative index of refraction, known as complex or metamaterials. The physics behind these materials is that at certain frequencies, these structures resonate, causing less power to be reflected or transmitted based on the material. The metamaterials that John has been working with are split-ring resonators (SRRs) and electric field couplers (ELCs). An SRR is a RLC circuit that couples with the magnetic field of an electromagnetic wave according to Faraday’s Law. An ELC is also an RLC circuit, but as the name implies, this circuit couples with the electric field portion of an electromagnetic wave. In this case, the tunability of the SRRs and ELCs is controlled by a DC voltage placed across a varactor diode in reverse bias, which causes the capacitance of the diode to change. In order to make the metamaterials more portable, a circuit was designed using an X9317 nonvolatile digital potentiometer and a DS2413 one-wire switch to allow the user to interface with a computer to change the settings of the potentiometer (changing the voltage across diode). The user can then set the desired resonant frequency, remove the metamaterial from the computer and not have the potentiometer settings change (preserving the resonant frequency.
John wishes to continue beyond his undergraduate studies by attending graduate school in electrical engineering and achieving his doctorate degree related to something in the field of solid-state devices or circuits.
Electrocardiographic Assessment of the Activation-Recovery Restitution Portrait
Supervising Professor: Dr. Salim Idriss, Pediatric Cardiology and Biomedical Engineering
Jamie Bell is a Senior Pratt Fellow in Biomedical Engineering studying the electrophysiological properties of cardiac tissue in order to better understand arrhythmia vulnerability in pediatric patients. She will be developing custom LabVIEW programs to measure the activation-recovery interval (ARI) restitution portrait from electrocardiographic data, and will use these programs to analyze clinical data. Previous research performed by Jamie Bell and Dr. Idriss has indicated that there are age-dependent differences in the restitution properties of cardiac tissue in vitro, and they hope to correlate their findings in the lab with the clinical data obtained.
Jamie’s Pratt Fellows Advisor is Dr. Salim Idriss, Assistant Professor of Pediatric Cardiology and Biomedical Engineering at Duke University. Jamie will be applying to MD programs after graduating and hopes to continue research in the future.
Moderating tumor drug distribution through a novel thermosensitive liposome delivery
Supervising Professor: Dr. Mark W. Dewhirst, Professor, Radiation Oncology, Biomedical Engineering, and Pathology
Jeffrey Birnbaum is a senior Pratt Fellow and a biomedical engineering major studying liposome drug delivery to tumors. Chemotherapy as a means to treat cancer is often ineffective, due to limited drug delivery and normal tissue toxicity. Nanoparticle drug delivery systems called liposomes have been developed that can limit these normal tissue toxicity issues, while depositing more drug directly to the tumor. Even more impressive is a lysolipid-based temperature-sensitive liposome (LTSL) formulation, which uses mild hyperthermia to trigger release of drug into a target area. When filled with the chemotherapeutic agent Doxorubicin (Dox), these Dox-LTSLs produce anti-tumor effects that far exceed the standard of care treatment of free Dox or the more traditional non-thermosensitive liposome formulation. However, the mechanism behind these anti-tumor effects is still largely uncharacterized. One hypothesis is that these effects arise from the quick release of drug from the liposome upon reaching a heated area, which can create a much larger gradient of Dox and perhaps cause Dox distribution to be pushed further into the tumor. This study will use histological sectioning of tumor slices post-treatment to determine if treating with Dox-LTSL plus heat yields enhanced distribution into the tumor over free Dox with or without heat. As current studies have shown that one of the major limitations of free Dox is limited penetration into tumor tissue, the results of this study may help in identifying LTSLs as a promising drug delivery system that may be particularly useful for distribution-limited drugs.
Jeffrey's Pratt Fellows Advisor is Dr. Mark Dewhirst, Professor of Radiation Oncology, Biomedical Engineering, and Pathology. After graduating in May 2009, Jeffrey plans on applying to MD/MPH programs and continuing to work on his research.
Tumor Cell Adhesion and Extravasation Under Flow Conditions
Supervising Professor: Dr. Fan Yuan, Biomedical Engineering
My research project looks at the effect of the protein tenascin-c on tumor cell extravasation. After building a novel flow-migration chamber, I was able to simulate the in vivo extravasation process using a closed loop flow system. Tumor cells migrate across a cultured endothelial monolayer, which models the lining of a capillary. By analyzing the number of migrated cells when tenascin is present or absent from the collagen network on the bottom of the membrane, I have shown that tenascin increases tumor cell extravasation and therefore migration. The extravasation process was simulated over a range of flow conditions that result in different shear stresses. The next phase of the project will be to repeat these experiments using leukocytes rather than tumor cells. It is currently postulated that the same protein, tenascin, that helps tumor cells migrate has the opposite effect on leukocytes.
After graduation I plan on working in industry for a few years before applying to medical school. I would like to continue doing research and would be interested in pursuing an MD/Ph.D degree.
Light Sensitive Logic Gated DNA Nanostructures as a Drug Delivery Platform
Supervising Professors: Dr. Stefan Zauscher, Mechanical Engineering, and Farshid Guilak, Biomedical Engineering and Orthopedic Surgery
David Chen is a Senior Pratt Fellow dual majoring in Biomedical and Electrical Engineering researching a novel drug delivery vector using light sensitive logic gated DNA nanostructures. His research involves testing the efficiency of a photocleavable motif for attachment and release of drug molecules on a DNA nanostructure. Once the photocleavable spacer is deemed usable, the next step would be to implement a Forster Resonance Energy Transfer (FRET) based logic gate with the output being cleavage of the photocleavable motif on the DNA nanostructure. Each DNA nanostructure is fully addressable and thus allows users to attach a multitude of different drugs or many molecules of the same drug onto the vector. This allows for the user to use the same batch of nanostructures to treat multiple ailments. The inclusion of light sensitive logic gates allows for drug safety in the form of binary logic encryption. The applications of such a drug delivery vector could be a “pharmacy in a pill” or improved drug safety at home and at hospitals.
David Chen’s Pratt Fellows Advisor is Dr. Chris Dwyer, Assistant Professor of Electrical and Computer Engineering at Duke University. David Chen will be applying to Ph.D. programs in the area of bioinstrumentation after graduating.
Characterization of Murine Articular Cartilage Surfaces
Supervising Professors: Dr. Stefan Zauscher, Mechanical Engineering, and Farshid Guilak, Biomedical Engineering and Orthopedic Surgery
Alex Cheng is a Senior Pratt Fellow in Biomedical Engineering who is seeking to characterize the surface of murine articular cartilage. Osteoarthritis affects a large population of adults, and is caused by a breakdown of articular cartilage from excessive wear. The tribological properties of cartilage that reduce friction are not well understood, and so our research is aimed at understanding the surface properties that give cartilage its low friction. One protein suspected to have cartilage reducing properties is lubricin, and so the main goal of this study is to compare the surfaces of cartilage in lubricin wildtype and knockout mice. The friction properties of cartilage samples from both types of mice will first be analyzed and imaged with the Atomic Force Microscope (AFM). The surface of the cartilage will also be imaged using the Scanning Electron Microscope (SEM). Finally, cartilage will be stained with different fluorescent tags and imaged in order to observe what other surface proteins could play a role in surface friction. The results from these imaging techniques will be compared in order to draw conclusions about what surface characteristics affect friction in lubricin wildtype and knockout mice.
Alex Cheng's Pratt Fellows advisors are Dr. Stefan Zauscher, Professor of Mechanical Engineering and Material Science at Duke University, and Dr. Farshid Guilak, Professor of Biomedical Engineering and Orthopedic Surgury at Duke University. Alex will be pursuing opportunities both in biotech industry as well as graduate school after graduation.
Image registration for OCT images
Supervising Professor: Dr. Joseph Izatt, Biomedical Engineering
Nigel Chou is a Senior Pratt Fellow in Biomedical Engineering exploring ways to register images of the retina obtained by Optical Coherence tomography(OCT). The motivation behind such a study is that summing and averaging successive B-scans of the same retina increases the signal-to-noise ratio, leading to a sharper image. However, due to patient movement, some translation and rotation occurs between each image, and these parameters need to be found and corrected for before the images can be averaged. The aim of his project is to be able to correct for these translations and rotations as quickly and accurately as possible, with the long-term goal of being able to register the images in real-time. Fourier-based registration methods were chosen to achieve this purpose. Although not the most accurate, they are among the fastest of known registration methods, and are robust to noise and intensity changes between images. Phase-correlation, a well-established method, has been used to register the images for translation. However, estimating rotation in the presence of translation is more involved, and requires finding the Polar Fourier Transform of an image. This is currently being done by first doing a regular 2D FFT, followed by a polar-transform by interpolation over the Cartesian grid. However, this method is inefficient and inaccurate, and more advanced methods of performing such a transform, such as the Pseudo-Polar FFT, are being explored.
Nigel Chou’s Pratt Fellows Advisor is Dr. Joseph Izatt, Professor of Biomedical
Engineering. He will be applying to PhD programs after graduating, and hopes to continue his research in the future.
Large-scale Wireless Sensor Networks to Measure Snow Pack Depth
Supervising Professor: Dr. Martin Brooke, Electrical and Computer Engineering
Andrew Cook is a senior Pratt Fellow in Electrical and Computer Engineering studying and designing wireless sensor networks to measure snow pack depth. the depth measurements themselves are conducted by transmitting a signal from above the snow pack to a series of wireless nodes underneath the snow. Due to the electromagnetic properties of waves passing between two media, the signal that arrives at the below-snow nodes will be both amplitude- and phase-distorted; the phase distortion is recorded, timestamped, and transmitted through the cloud network until it arrives back at a base station system. At this base system, the timestamped phase data are converted into depth measurements, thus eliminating the need for additional sensors or physical measurement of the snow depth. Andrew has tested a number of wireless nodes created for sensor networks by Crossbow technologies in air and water to determine transmission efficacy, using TinyOS and customized code to create small sensor networks. Additionally, he has tested the nodes in a large sample of snow substitute foam created by Regicell to determine if the nodes will transmit capably in actual snow. Transmission in all three media has been acceptable, so Andrew will now begin designing circuit boards for use with a different type of wireless node (a Jennic module with built-in ceramic antenna) and begin conducting depth measurements with new customized hardware. The ultimate goal of this project is a distributed, cheap, under-snow system for obtaining accurate and timely measurements of snow pack depth autonomously.
Harvesting Energy from Ocean Waves
ME 2009 / MEM 2009
Supervising Professor: Dr. Jeff Scruggs, Civil Engineering
This project is a study of the nature of ocean waves and how
energy can be harvested from their movement. Last semester was spent
modeling the response of cylindrical buoys to various forces they will
experience when placed in the ocean. These buoys are initially
affected by the excitation force of the incumbent waves; this is
completely independent of the motion of the buoy. After the buoy is
set in motion by the incumbent wave, the frequency response of the
buoy causes a radiation force to occur. The combination of these
forces makes up the wave response, allowing for the modeling of
several buoy characteristics. The ideal power output of the buoy was
calculated and plotted at various resonance frequencies. Then, both
low and high pass impedance matched controllers were designed and
plotted against ideal power output, to show various possibilities for
the controller that will eventually be put into the system.
Theoretically, the controllers should extract the most power from the
oscillating buoy at its resonance frequency. However, the key when
picking controllers is to choose one that will extract the most power,
the majority of the time. This semester, the physical experiment is
under construction, with results to come early next spring.
Kat's Pratt Fellows Advisor is Dr. Jeff Scruggs, Assistant Professor
of Civil Engineering at Duke University. Kat will be commissioned in
the United States Navy in May, and is looking to work with the nuclear
propulsion program. She hopes to continue her research in the field of
alternative energy in the future.
Enhancing Nanostructured E-fields with DNA-linked Nano-Assemblies
Janessa Weng-Hong Det
Supervising Professors: Dr. Anne Lazarides, Mechanical Engineering &
Materials Science, and Dr. Tuan Vo-Dinh, Biomedical Engineering
Janessa Det is a Senior Pratt Fellow in Biomedical Engineering working to develop and optimize a nanostructure consisting of metal colloids linked together with DNA, which enhances electric fields. The use of DNA linkers allows accurate control of interparticle distances and self-assembly abilities for the intended nanostructures. Variables in consideration for optimization of such a nanostructure include metal type, gold, silver, or platinum; linker type and length; and nanoparticle size. By experimenting with these variables, an optimal nanostructure involving three particle classes is being developed. The enhanced electric fields generated by these structures would decrease the signal to noise ratio for detection methods such as Raman Spectroscopy leading to improvements in a wide variety of potential applications such as ultrasensitive detection of biomolecules.
Supervising Professor: Dr. Zbigniew Kabala, Civil and Environmental Engineering
Scott Harvey is a Senior Pratt Fellow in Civil and Environmental Engineering
studying the dipole-flow test. The dipole-flow test is a novel measurement technique for
aquifer characterization, particularly suitable for vertical-circulation wells used in
groundwater remediation. Scott initially used the Laplace transform and finite Fourier
cosine transform to non-dimensionalize the mixed-type boundary value problem for a
partially penetrating well followed by numerical simulations using Mathematica. He
used these results to construct a novel semi-analytic solution for the dipole-flow test via
superposition principle. Presently, the simplifying assumption of a uniform flux through
the well screens is being relaxed and a non-uniform well-face flux condition is being
tested with the stipulation of zero flux along the unscreened portion. Possible future
work includes interpreting field experimental data obtained using the dipole-flow device
designed by Drs. Kabala and Schaad at the Lizzie site in North Carolina.
Scott’s Pratt Fellows Advisor is Dr. Zbigniew Kabala, Associate Professor of
Civil and Environmental Engineering at Duke University. Scott is currently applying to
Structural Engineering M.S. programs and intends to practice structural design after
The Impact of Interleukin-17 on Degenerated and Herniated Intervertebral Disk Tissue
Supervising Professor: Dr. Lori Setton, Biomedical Engineering
Antonia Helbling is a senior Pratt Fellow in Biomedical Engineering analyzing the effect of immune system proteins on diseased intervertebral disk tissue. She has developed a protocol to evaluate the inflammatory response of the cells co-stimulated with IL-17 and interferon-?, and has obtained preliminary results. The number of different patient samples evaluated is currently being increased to determine variability among humans with the same kind of disk disorder. The effects of IL-17 on intervertebral disk tissue have not yet been evaluated in the scientific literature. Understanding the interplay of these body components, which are isolated from each other in healthy tissue but may come in contact when the disk is diseased, may provide a foundation for therapy for intervertebral disk disease.
Toni’s Pratt Fellows Advisor is Dr. Lori Setton, Professor of Biomedical Engineering and Orthopaedic Surgery at Duke University. Toni is currently applying to medical schools, where she hopes to continue to explore her clinical and research interests in orthopaedics.
Characterization of Endothelial Progenitor Cells for use in prosthetic vascular grafts
Supervising Professor: Dr. William Reichert, Biomedical Engineering
Enping Hong is a senior biomedical engineering Pratt Fellow studying the properties of endothelial progenitor cells (EPCs) for use in synthetic blood vessel grafts. The formation of an endothelial layer improves the lifespan of such grafts, and the highly proliferative EPCs are excellent candidates for such endothelialization. Enping is characterizing EPCs from patients with and without coronary artery disease in response to prolonged laminar shear stress, and is examining how the expression of key genes changes after such exposure. The characterization of such expression would present a better understanding of how EPCs are affected under flow, how coronary artery disease affects this expression, and how this response differs from control cells like aortic endothelial cells. A recent collaboration with the NIH has allowed for the testing of several thousand genes, and the results are eagerly anticipated.
Enping’s Pratt Fellows advisor is Dr William M. Reichert, Professor of Biomedical Engineering, and Director of the Center for Biomolecular and Tissue Engineering. He will be applying to PhD programs after graduation, and aims to specialize in tissue engineering.
Cancer Therapy Assessment using Optical Spectroscopy
Supervising Professor: Dr. Nimmi Ramanujam, Biomedical Engineering
Anti-angiogenesis therapy has currently gained the spotlight as an effective means in cutting off the life support to malignant tumors. Optical spectroscopy provides a non-invasive, quick, and inexpensive means of assessing tumor vasculature. Using the reflected spectrum and the fluorescence of the sample, numerous physiological parameters are extracted. My current research focuses on the ability to predict tumor response to various therapies. We recently completed a 40 animal mouse study to optically evaluate the effects of a single, acute radiation treatment. By accurately predicting a tumor’s response, oncologists can specifically tailor the treatment to produce maximum effectiveness. Besides pre-clinical work, I am currently working with the VA hospital to use our optical probe on in vivo mouth and throat cancers.
After graduation, I plan on pursuing a career in the private sector of biomedical engineering.
Transport Properties of HIV, HIV Antibodies, and Microbicides in
Simulant Cervical Mucus and Gels
Mary Ellen Koran
Supervising Professor: Dr. David Katz, Biomedical Engineering
Mary Ellen Koran is a Junior Pratt Fellow in Biomedical Engineering
studying the transport properties of HIV, HIV antibodies, and microbicides
in cervical mucus. She will first test these properties in a polymer
based cervical mucus simulant, then test the transport properties of bovine
and human cervical mucus, compare the properties of real and simulant mucus,
and alter the simulant if the properties differ. Currently, the diffusion
coefficient of the simulant is being studied to test the simulant's
degradation over time. The transport properties of the cervical mucus of
the human reproductive tracts have not been studied in depth, and improving
the simulant will make studying the mucus easier for future researchers. Studying
this mucus will increase our knowledge of how HIV molecules travel though
this mucus to infect women. This project will also analyze how microbicides
or antibodies in the mucus can slow down or stop the virus from entering the
vaginal tissue, hence preventing the infection of the female reproductive
Mary Ellen's Pratt Fellows Advisor is Dr. David Katz, Professor of
Biomedical Engineering, and Obstetrics and Gynecology at Duke University. Mary Ellen will be applying to MD/PhD programs after graduating, and
hopes to continue her research in the future.
Biodiesel Production from Microalgae
Supervising Professor: Dr. Claudia Gunsch, Civil and Environmental Engineering
I am a Senior Pratt and General Motors Fellow in the department of Civil and Environmental
Engineering working on a project that will study biodiesel production from microalgae. The
recent attention given to alternative energy sources is transforming the research done in
this field and one of the upcoming sources of alternative fuel is biodiesel from
microalgae. Known to have a percentage yield many times higher than their plant
counterparts of raw lipid, microalgae can become a promising fuel source. However, one of
the largest obstacles in using microalgae is the efficiency of growth, harvest, and
processing involved in large-scale production. This particular research project will
target the growth portion of microalgae, namely identifying the particular growth
regime (i.e. light/dark cycles, autotrophic/heterotrophic, etc.) that will maximize
lipid production in the algae. This will be done by monitoring the growth characteristics
of algae under various conditions and employing standard environmental technologies such
as chemical oxygen demand (COD) testing. The set of conditions determined to maximize
lipid production will then be used in the design of a bioreactor for microalgae
My Pratt Fellows Advisor is Dr. Claudia Gunsch, Assistant Professor of Civil and
Environmental Engineering at Duke University. Partial funding for this project comes from
a General Motors grant. After graduation, I plan on attending graduate school for a
master’s in environmental engineering.
Cardiac Lesion Imaging with Acoustic Radiation Force Impulse (ARFI) Ultrasound
Yang (Ashley) Li
Supervising Professor: Dr. Patrick Wolf, Biomedical Engineering
Yang Li is a Senior Pratt Fellow in Biomedical Engineering and Electrical Engineering. Her project focuses on designing a method to image ablated heart lesions with Acoustic Radiation Force Impulse ultrasound in vitro. She first ablates a lesion on a piece of tissue and image the lesion with ARFI ultrasound. She then slices the tissue along the imaging plane and takes a digital pathology picture of the plane surface. She has collaborated in developing an semi-automatic program to register the ARFI image with its pathology picture to increase efficiency and to show the possibility of an automated registration program in the future. Her next step is to reconstruct a 3-D lesion image to test and modify the registration program.
Yang Li's Pratt Fellows Advisor is Dr. Patrick Wolf, Associate Professor of Biomedical Engineering.
Developing Elastin-Like Polypeptide based Drug Carriers
Supervising Professors: Drs. Mingnan Chen and Ashutosh Chilkoti, Biomedical Engineering
Kun Liang is a Senior Pratt Fellow in Biomedical Engineering studying the capabilities of Elasin-Like Polypeptides (ELP) as drug carriers. His first task is to study the immunogenicity of ELP with different chemical compositions. He aims to investigate the effects of varying composition of ELP on the absorption of the ELP-attached drug molecule in tissues affected with viruses. Currently, he has prepared a ELP with different number of repeat units (fewer leading and trailing sequences) and ready to test the ELP with immune assays. His other task was to prepare an ELP-based construct to target ovarian cancer cells. In this construct, he will include LHRH receptor site for the ovarian cancer cells as well as protease expression sequence that is overexpressed in those cells as well. Therefore this peptide will be highly specific to the target tissue. Right now he has prepared parts of the construct with PCR reactions of single-stranded DNA sequences and he has isolated these DNA through DNA cloning techniques. In the future, he will prepare more versions of the basic construct with different proteases and receptors and test the drug carrier on ovarian cancer cells in mice.
Kun Liang's Pratt Fellows Advisor is Dr. Mingnan Chen and Ashutosh Chilkoti, Professor of Biomedical Engineering at Duke University. He plans to go to graduate school and continue bio-related research.
Ling, Vincent - Engineering an Efficient Biopathway for the Bioplastic poly(3-hydroxybutyrate-co-4-hydroxybutyrate)
Supervising Professor: Dr. David Katz, Biomedical Engineering
Vincent Ling is a Senior Pratt Fellow in Biomedical Engineering studying the biopathway for bioplastics production. Polyhydroxyalkanoic acids (PHA) are naturally occurring storage polymers found in a variety of bacteria and have received increased attention for their potential use as bioplastics that are both biodegradable and reduce reliance on petroleum-based plastics. In particular, the copolymer poly(3-hyroxybutyrate-co-4-hydroxybutyrate), or poly(3HB-co-4HB), has elastic properties ideal for a wide range of thermoplastic applications. However, the high cost of PHA is the biggest impediment to widespread use of bioplastics, and the current poly(3HB-co-4HB) yields undesirably low 4HB-to-3HB ratios.
For this research, various biopathways for poly(3HB), poly(4HB), and poly(3HB-co-4HB) have been constructed, and polymer production has been confirmed by NMR. Current research is focusing on developing a more efficient biopathway for poly(3HB-co-4HB) by using codon optimization techniques on the phaA, phaB, phaC, and cat2 genes in each separate pathway. In addition, the poly(3HB-co-4HB) will be optimized to produce a high and predictable 4HB-to-3HB ratio as well. Ultimately, the goal is to develop a model for mass production of PHA bioplastics so that novel applications of bioplastics can be feasible economically.
Vincent’s Pratt Fellows Advisor is Dr. Jingdong Tian, Assistant Professor of Biomedical Engineering at Duke University. Vincent will be applying to JD programs after graduating, and hopes to continue his interest in biomedical research through intellectual property law.
Acoustic Radiation Force Impulse Imaging
Supervising Professor: Dr. Gregg Trahey, Biomedical Engineering
David Liu is working on acoustic radiation force impulse (ARFI) imaging. ARFI is a new form of ultrasound imaging, using focused ultrasonic energy to displace tissues within a patient’s body. The displacements are then tracked, and used to calculate the tissues’ mechanical properties. ARFI gives physicians additional information not obtainable through conventional imaging techniques. A specific focus of David’s research is on improving the image processing algorithms used in ARFI calculations. With the aid of finite element model computer simulations, David hopes to optimize the current motion filtering algorithms used for ARFI. The success of this project will improve the accuracy of ARFI calculations.
David’s Pratt Fellows Advisor is Dr. Gregg Trahey, Professor of Biomedical Engineering at Duke University. He is also working under the supervision of Dr. Jeremy Dahl, Assistant Research Professor.
David is currently applying to medical schools, and believes his research experience will help him both as a medical student and as a future physician.
Transient Pumping Schemes for Efficient Remediation of Porous Media
Supervising Professor: Dr. Zbigniew Kabala, Civil and Environmental Engineering
The present durations for pump-and-treat remediation of contaminated groundwater span
magnitudes of years, decades, and even centuries. Currently, pump-and-treat methods
extract water from the contaminated soil, clean it, and then pump it through the contaminated
site again, in an endless cycle of flushing until a wanted concentration is attained.
The amount of contaminant decreases relatively fast, but then tails off at a concentration
usually above regulatory standards. One reason for this tailing off is matrix diffusion,
where, as contaminants flow more easily through permeable areas of soil, concentration
gradients between permeable and less permeable areas evolve. These gradients cause
contaminant to diffuse into the less permeable areas of the media, where they are made
effectively immobile. It is in my research that I hope to decrease the existence of
these immobile areas that arise due to matrix diffusion by examining a model of a single
pore of soil. It has been seen in other areas that contaminant removal occurs the most
during the unsteady start up of an engineering system. Using these observations, I hypothesize
that transient pumping rates should significantly increase the cleanup efficiency of porous
media, and thus should lead to significant shortening of required pump-and-treat times and
costs. So far in my research, I have learned the flow modeling software, FIDAP, and have
modeled steady state through a single pore. I have seen, that as observed before by many,
steady-state flow barely penetrates a pore, and thus does not have any impact on the
contaminant within it. I am now currently working on programming the transient scheme for
the model, which I hope to run soon and see that it is more capable of penetrating a pore.
Chloe is a Pratt Fellow with Dr. Zbigniew Kabala and plans on attending graduate school to study water resources engineering after graduation.
Genetically Engineered pH-responsive Micelles for Drug Delivery to Solid Tumors
Supervising Professor: Dr. Ashtosh Chilkoti, Biomedical Engineering
Michael McGroddy is a Senior Pratt Fellow in Biomedical Engineering working to develop a more pH-sensitive protein to be used in localized drug delivery to tumor cells. Since the pH within the extracellular environment of tumor cells is slightly more acidic than the rest of the body, members of the Chilkoti lab have developed proteins that can be designed to release drugs upon encountering an acidic environment. Michael has studied the properties of these proteins and is working to engineer E. coli bacteria to produce a protein that exhibits a higher degree of sensitivity to changes in pH. Currently Michael is trying to synthesize bacterial plasmid genome that will carry an inserted DNA segment that codes for this protein. Once this is accomplished he will characterize the properties of this new protein to see if a higher pH-sensitivity is achieved. The success of this project will enable future researchers to design drug carriers that can better “recognize” the slight changes in pH within tumors.
Michael’s Advisor, Dr. Ashtosh Chilkoti, is a professor with Duke's Department of Biomedical Engineering, and Associate Director of the Center for Biologically Inspired Materials and Materials Systems. Michael plans to apply to MS programs after graduating and hopes to continue his research in the future.
Mobility Prediction Methods for Realtime Location Privacy
Supervising Professor: Dr. Romit Roy Choudhury, Professor of Electrical and Computer
Engineering and Computer Science
Joseph T. Meyerowitz is a Senior Pratt Fellow in Electrical and
Computer Engineering studying technical issues related to privacy and
mobile devices. As GPS and other localization technologies become
increasingly ubiquitous, new location-based services are being offered
to mobile users. These services frequently require a constant stream
of location updates from mobile users. The potential for continuous
tracking of mobile users poses a clear privacy risk. Our work focuses
on preserving the usefulness of these location-based services while
protecting mobile users' privacy. Existing methods in location
privacy often reduce the accuracy of the user's GPS coordinates or
prevent realtime communication. We are investigating the use of
mobility prediction and caching to proactively store data from
location-based services before users request it. The end-goal is to
camouflage the user's path with preemptive requests for data in a way
that prevents tracking the user's exact location, but still allows the
user to get location-based data in realtime.
Joseph T. Meyerowitz is advised by Romit Roy Choudhury, an Assistant
Professor of Electrical and Computer Engineering and of Computer
Science. He plans to pursue a Ph.D in engineering or computer
science, with an anticipated focus on nanostructure fabrication and
Modelling the effects of climate change on Dripsey, an Irish watershed
Supervising Professor: Dr. John Albertson, Civil and Environmental Engineering
Nicholas Millar is a Senior Pratt Fellow in Civil and Environmental Engineering studying how climate change will alter the soil properties and soil characteristics in an Irish water basin. Using a previously established model, Geotop, the water shed will be studied and the model adjusted to get a better understanding of what the future holds not just for Ireland but elsewhere in the world as well. With the help of his advisor, he is currently calibrating the model to better reflect the Irish watershed (since the model was created for Italian soil characteristics, a far different environment). The model will then be changed with greater storm events and the transport of soil carbon and other properties will be analyzed for better understanding of landslides and other major soil events.
Nicholas Millar's Pratt Fellows Advisor is Dr. John Albertson, Professor of Civil and Environmental Engineering at Duke University. Nick is unsure of his future plans and his considering both PhD programs and private industry.
Acetic Acid as a Contrast Agent for Breast Margin Assessment using Tissue Optical Spectroscopy
Jessica Munn is a Senior Pratt Fellow in Biomedical Engineering studying the use of acetic acid as a contrast agent for breast cancer margin assessment. This study uses the properties of light to detect breast cancer on the margins of excised tissue and is developing the technology to allow surgeons to use this information during the initial breast-conserving operation. She is exploring acetic acid as a cheap and easy method to enhance the signal in order to make cancerous areas apparent in several methods of image acquisition. Along with an adding an acetic acid data acquisition protocol to the normal operating procedure of the margin assessment that utilizes fiber optic technology, she is also developing a system that uses acetic acid, UV light and post processing in MATLAB to image the breast cancer with just a simple digital camera capable of RAW formatting. Next year Jessica plans to pursue a career in security analysis.
Role of rhoA activation in focal adhesion formation and endothelial cell attachment
to different substrates
Supervising Professor: Dr. George Truskey, Professor and Chair, Biomedical Engineering
Amy Munnelly is a Senior Pratt Fellow in Biomedical Engineering studying the adhesive and
functional properties of endothelial cells in monoculture and in coculture with smooth
muscle cells. It is known that endothelial cells in monoculture form focal adhesions,
while those in coculture form fibrillar adhesions. Focal adhesions are protein complexes
primarily located at the cell periphery that connect the cytoskeleton to the extracellular
matrix. The small GTPase protein rhoA regulates the formation of stress fibers found in
focal adhesions. Currently Amy is working to determine if rhoA is activated at different
levels in endothelial cells in coculture as compared to monoculture. She will transfect
the endothelial cells with myc-tagged rhoA adenovirus, plate the transfected cells on
fibronectin-coated plastic or smooth muscle cells, and allow the cells the spread.
RhoA activation will then be quantified using a rhoA pulldown activation assay and a
Western blot for the activated myc-tagged rhoA using a myc-specific antibody. These
studies will provide information about the mechanisms underlying the formation of focal
adhesions in monoculture and the deficiency of focal adhesions in coculture.
Amy’s Pratt Fellows Advisor is Dr. George Truskey, Professor and Chair of Biomedical
Engineering at Duke University. Amy will be applying to bioengineering MSE programs
and hopes to enter the biomedical device industry in the future.
OPERA - Ominidirectional Phone Enhanced Ranged Acoustics
Supervising Professor: Dr. Jeffery Krolik, Electrical and Computer Engineering
Jonathan Odom is a Senior Pratt Fellow in Electrical and Computer Engineering studying array signal processing in the Sensor Array and Multipath Signal Processing Lab. He has been simulating and implementing beamforming algorithms for a microphone array to be used for capturing sounds, specifically speech, in large rooms. The purpose of the research is to replace standard microphone products, such as lecture stands or wireless microphones, with a single microphone array. He is experimenting with conventional beamforming methods and exploring Minimum Variance Distortionless Response (MVDR) beamforming. Loudspeakers create correlated sources that greatly deteriorate the performance of statistical beamformers such as MVDR. Acoustic sources will be in the near-field of the array, which presents a problem with near-field, correlated sources. He plans to design additions to MVDR, such as pre-processing in order to allow MVDR to adaptively null near-field, correlated interferers. This research will result in a prototype using NIST MARK III microphone arrays.
Jonathan's Pratt Fellows Advisor is Dr. Jeffery Krolik, Professor of Electrical and Computer Engineering at Duke University. Jonathan will be applying to PhD programs after graduation, and hopes to continue his research in the future.
Preclinical Imaging using Nanoscale Liposomal Contrast Agents
Supervising Professor: Dr. Srinivasan Mukundan Jr., Radiology, Biomedical Engineering and Chemistry
As a Senior Pratt Fellow, Neil has been investigating the use of liposomes as a vehicle to deliver contrast agents for computed tomography (CT) and magnetic resonance (MR) imaging. Liposomes allow either iodine-based CT contrast or gadolinium-based MR contrast to remain in circulation for a much longer period of time than conventional, non-liposomal agents. Neil has synthesized nanoscale vesicles containing high concentrations of contrast that can be used for various applications. Preclinical micro-CT studies in murine models have produced images that exhibit high-enhancement with submillimeter resolution. As well, gadolinium-containing liposomes have been successfully used for contrast-enhanced MRI and MR angiography applications where rapidly diffusing gadolinium chelates are inadequate. Neil is currently in the process of preparing a manuscript reporting the work of his group in these areas that will be submitted to a major scientific journal in the coming weeks. Afterward, he hopes to examine the clearance behavior of liposomes in vivo to ascertain their feasibility as a clinical tool.
Neil’s Pratt Fellows Advisor is Dr. Srinivasan Mukundan Jr., Assistant Professor of Radiology, Biomedical Engineering, and Chemistry at Duke University, Associate Professor of Radiology at Harvard Medical School, and Director of Radiology at Brigham and Women’s Hospital in Boston. Neil is currently in the application and interview process for MD programs, and plans to cultivate his research interests as a physician.
Planning and Implementing an Environmental Engineering Educational
Outreach Program for CLEANER WATERS in the Neuse River Basin
Lindsay Ann Rawot
Supervising Professor: Dr. J. Jeffrey Peirce, Civil and Environmental Engineering
Lindsay Ann Rawot is a Senior Pratt Fellow in Civil and Environmental Engineering studying the how the proposed CLEANER (Collaborative Large-Scale Engineering Analysis Network) and
WATERS (WATer and Environmental Research Systems) Networks can be used to transform
middle-school science education. Starting in the Neuse River Basin, Lindsay is designing and
implementing an educational curriculum unit that will bring environmental engineering within
the grasp of the nation’s most impressionable young minds. Her program utilizes the power of
real-world data from WATERS in conjunction with wet-lab learning and an online interactive
CyberCollaboratory to engage students in the fields of engineering, environmental science,
chemistry, biology, and technology. After classroom implementation, Lindsay will utilize
feedback from educators and students to improve the program and publish her results on how
to extend this program to classrooms nationwide.
Lindsay Rawot's Pratt Fellows Advisor is Dr. J. Jeffrey Peirce, Associate Professor of Civil and Environmental Engineering. Lindsay Rawot will seek a Masters degree in Environmental
Engineering after graduating, and hopes to continue her research in the future.
3D Ultrasound Guidance of Autonomous Robot for Location of Ferrous Shrapnel
Supervising Professor: Dr. Stephen Smith, Biomedical Engineering
AJ Rogers is a biomedical engineering major with a chemistry minor. He is a senior Pratt Fellow studying under Dr. Stephen Smith. Feasibility study for automated location of shrapnel with phased-array 3D ultrasound. In some emergency situations, shrapnel detection in the body is necessary for quick treatment. Dangerous conditions or evacuation situations may limit the use of bulky fluoroscope imaging. Furthermore, small or uneven shrapnel geometry may obscure foreign bodies inside a patient from typical ultrasound detection methods. In the event that other options are not available, real time 3D ultrasound offers a viable solution. Vibrations induced in ferromagnetic shrapnel by a variable electromagnet cause small displacements in surrounding tissue. Phased-array 3D ultrasound has the ability to locate this motion in the tissue volume caused using Doppler techniques. Color flow Doppler offers increased contrast, and thus easier detection, for the shrapnel. Real time 3D ultrasound offers the ability to scan a volume of data rather than a single plane to find the three dimensional coordinates of objects of interest. The absolute position of the foreign body can then be coordinated with a surgical robot for emergency treatment.
Future work will be conducted to move from shrapnel detection to lesion detection in
soft tissue. The scanner will interface with an improved robot with seven degrees of freedom
for more complex movements and control. The ultimate goal for this project is to perform
autonomous robotic soft tissue biopsy using ultrasound guidance.
AJ plans to attend medical school at the University of North Carolina at Chapel Hill when he graduates.
Exploring Methods of Treating Osteoarthritis: Comparing Chondrogenesis in Adipose
and Mesenchymal Stem Cells
Supervising Professor: Dr. Farshid Guilak, Orthopedic Surgery
Chris Rowland is a senior Medtronic Pratt Fellow in biomedical engineering studying
growth factor mediated chondrogenesis in adipose (ASCs) and mesenchymal (MSCs) stem
cells. The goal of his research is to measure the potential of chondrogenesis of both
cell types in a nonbiased manner. He first conducted a cross-comparison between adipose
stem cells and mesenchymal stem cells in each of their respective chondrogenic cocktails.
The study was first carried out in an alginate bead system, in which the cells received
minimal signals from the scaffold other than being arranged in a 3D structure. The study
was then repeated in cartilage-derived, porous-matrix scaffolds, in which the cells were
seeded in scaffolds, composed of native cartilage. In this system the cells adhered to the
scaffolds and received chemical and mechanical signals from the native cartilage scaffold
as well as growth factors. The extent of chondrogenesis was determined by measuring levels
of gene expression and protein synthesis. A future study will test the hypothesis that
ASCs do not naturally express TGF-B3 receptors; however, they can be induced to express
these receptors by BMP-6. Once ASCs begin expressing TGF-B3 receptors, they will be able
to respond to TGF-B3 present in the medium, and undergo chondrogenesis to the same extent
as MSCs. A long term goal of this research is to be able to grow native cartilage in vitro,
which will serve as a replacement for damaged cartilage in osteoarthritis.
Chris Rowland’s Pratt Fellow advisor is Dr. Farshid Guilak, Director of the Orthopedic
Bioengineering Laboratory at Duke University. Chris will be applying to PhD programs in
the fall, and hopes to pursue a doctorate degree in the field of Orthopedic Tissue
Biological Response of Monocyte/Macrophage Cells to Topographical Cues
Supervising Professor: Dr. Kam W. Leong, Biomedical Engineering
Ami Saheba is a Senior Pratt Fellow in Biomedical Engineering involved in the study of topographical cues effect on monocyte/macrophage behavior in the foreign body reaction to polymeric implants. Specifically, she is involved in fabricating non-woven poly(e-caprolactone) (PCL) fibers of micron and nanometer scale topography of random and aligned orientation. These substrates are fabricated using electrospinning technique, in which Ami optimizes the fabrication process parameters such as electric field, polymer/ solvent concentration and fiber extrusion / collection dimensions, and characterizes the resultant random versus aligned fibers by scanning electron microscopy (SEM). This is critical to producing finely controlled fibers of the correct dimensions and orientation for in vitro cellular studies. Monocyte/macrophage morphology, proliferation and differentiation on these synthetic biocompatible substrates are studied to determine if topography and fiber orientation that mimic in vivo extracellular matrix (ECM) organization affect the foreign body reaction. The effect of topography on modulating the response of monocyte/macrophage cells, such as cytokine production profile, macrophage recruitment, foreign body giant cell (FBGC) fusion and matrix remodeling, will be investigated. This research allows better mechanistic understanding of the foreign body reaction to biomedical implants which currently lead to high rates of implant failure.
Ami’s Pratt Fellows Advisor is Dr. Kam W. Leong, Professor of Biomedical
Engineering at Duke University. Ami will be pursuing a Masters in Biomedical Engineering at Duke University and then continuing on to a career in industry.
EEngineering Optimal Cell Culture Platform Using Micro-/Nanotechnology
Jaren Junren Sia
Supervising Professor: Dr. Kam Leong, Biomedical Engineering
Jaren has been assisting his mentor, Dr Yong Yang, closely in his research to develop 3D nanoscale patterns to regulate the fate of stem cells. He started with mastering the technique of fabricating nanopatterns in PDMS, and incorporating these nanopatterns into a microfluidic device. Bone marrow derived human mesenchymal stem cells are seeded into this device and their angles of orientation and axis ratios are measured after several days of incubation. The device has gone through several modifications and currently they are in the stage of results collection. The next step would be to culture hematopoietic stem cells. A large channel volume is needed and Jaren is optimizing the process for fabricating photolithographic features with high aspect ratio so that a mold for deep channels can be made.
Jaren is planning to attend graduate school in engineering.
External Cavity Diode Laser Construction for Use in Quantum Information Processing
Supervising Professor: Dr. Jungsang Kim, Electrical and Computer Engineering
Michael Silver is a Senior Pratt Fellow in double majoring in Electrical and Computer
Engineering and Physics who studies optics and electromagnetic fields. His research focuses
on designing a laser that emits light at specific frequencies to be used in electron
transitions in Ytterbium ions. Creating this will allow for the successful detection
and manipulation of electrons to be read as ones and zeros for bit processing. To create
an external cavity a holographic reflection grating is used to separate the wavelengths
inherent to the laser and reflect back to the laser diode the desired wavelength. This
creates a smaller bandwidth in the output of the system and increases the output optical
power at the desired frequency. In the future this can be used as a fundamental piece in
Michael Silver's Pratt Fellows Advisor is Dr. Jungsang Kim, Professor of Electrical and
Computer Engineering. After graduating Michael plans on going into the engineering industry and looks to continue research in the future.
Dynamic Modeling of various Forced Mass Systems
Supervising Professor: Lawrence Virgin, Professor and W.H. Gardner Jr. Department Chair of Civil and Environmental Engineering
The current research revolves around the dynamic modeling of various systems, specifically systems with a vibrating mass, or masses under the influence of impact forces. Studies were conducted involving a mass attached to a string on a vibrating surface moving in
1D linear motion being tracked and recorded with a high-speed digital camera and computer
software. This data was compared with the predicted results given by 2 software codes coded in Matlab and Simulink to model the motion of the mass. In addition, the software codes were modified in order to better predict the mass system after a number of trials. Future work involves expanding both the modeling codes and the physical setup to measure and predict 2D motion of the same mass. Other current work includes the modeling of a 2D system involving a ball on a plate attached to a shaker. The overall goal is to achieve dynamic models that correctly predict the motion of the masses in repeated experiments which can then be expanding to broader applications and practical use.
Quantitative Analysis of Electrical Excitation of Cortical Neurons
Supervising Professor: Dr. Warren Grill, Biomedical Engineering
Whitney Stewart is a Senior Pratt Fellow in Biomedical Engineering studying the
electrical excitation of cortical cells from DC electrical fields and
extracellular current stimulation. In order to study the excitation behavior,
she will modify and use models of cortical cells that have already been
developed for the Neuron Simulation Environment. Analysis of the mathematical
Hodgkin-Huxley model based on the squid axon suggests that only extracellular
voltages with a non-zero second spatial derivative will be able to initiate an
action potential. When dealing with smaller human neurons with a complex
dendritic structure, however, she has successfully generated action potentials
in a spatially constant electric field. She has studied the threshold field
strengths at various orientations and durations. This data will improve our
ability to treat a variety of disorders using Transcranial Magnetic Stimulation
and Cortical Stimulation while minimizing side effects by improving stimulation
specificity. She has also started work on generating a 3D map of current
thresholds from a point source around the cortical cell model. Preliminary maps
already show patterns that she hopes will be able to act as a guide for
neurosurgeons when implanting a cortical or deep brain stimulation device.
Whitney's Pratt Fellows Advisor is Dr. Warren Grill, Professor of Biomedical
Engineering at Duke University. Whitney will be applying to medical school
after graduation and hopes to continue studying new methods of neural
Optimization of the ratio of 4HB to 3HB monomers incorporated in
bacterial production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate)
Di (Sandy) Sun
Supervising Professor: Dr. Jingdong Tian, Biomedical Engineering
Sandy Sun is a senior Pratt Fellow working in Dr. Jingdong Tian?s lab. Her
project concerns the bacterial production of biopolymers, which are a green
alternative to current petroleum-based plastics because they are both
biodegradable and renewable. This class of materials includes bioplastics such
as polyhydroxyalkanoates (PHA) and is produced through microbial fermentation of
sugars and oils. I am working to develop a specific PHA,
poly(3-hydroxybutyrate-co-4-hydroxybutyrate), also known as poly(3HB-co-4HB),
through cloning the requisite genes into E. coli. Poly(3HB-co-4HB) has greater
elasticity, yielding greater therapeutic potential, including use in medical
implants. The development of this plasmid involves assembly PCR, restriction
enzyme digestion, ligation, transformation, and various other lab techniques.
Currently, the lab has verified the production of poly(3HB) by NMR. Future work
will include optimizing the protein that polymerizes poly(3HB-co-4HB) to
increase the ratio of 4HB monomers in the copolymer, codon optimization to
increase overall polymer production, and development of an effective method to
screen bacteria producing the copolymer.
Dr. Jingdong Tian is an assistant professor of the Biomedical Engineering
Department. Sandy is a senior BME major; she hopes to attend medical school
after graduation and pursue a career in academic medicine.
Low-threshold Photonic Crystal Lasers
Supervising Professor: Dr. Tomoyuki Yoshie, Electrical and Computer Engineering
Pantana Tor-ngern is a Senior Pratt Fellow in Electrical Engineering studying and designing the low-threshold photonic crystal lasers. Compact photonic crystal lasers are expected to be energy efficient and have low threshold power. Given a material containing many carriers, one has to give certain power to the system such that electrons transit to their excited states, the condition called population inversion. Once the input power reaches its threshold, laser emission will occur. Thus, the threshold of a laser is the condition when the gain of the laser equals its loss. Gain is limited for small lasers so the low threshold condition requires an ultra-low-loss resonator. Previous research suggests that using quantum dot gain media results in the low threshold of laser. In this project, she will design a high-Q photonic crystal cavity and analyze its resonant mode. Then, she will be involved in the fabrication process. The approach here is to reduce the density of quantum dots in the gain media to only one single quantum dot. However, she is currently aiming for a slightly different direction. She is attempting to make a current injection photonic crystal laser. The study and analysis of this new idea are very similar to the low-threshold photonic crystal laser. The only difference is that we try to incorporate metal with the photonic crystal structure, instead of the usual free-standing structure. This new approach will enable the integration of photonic devices with CMOS technology, enhancing the practicality of photonic findings.
Pantana's Pratt Fellows Advisor is Dr. Tomoyuki Yoshie, Assistant Professor of Electrical and Computer Engineering at Duke University. Pantana will be applying to PhD programs in Electrical Engineering/Applied Physics after graduating, and hopes to continue her research in Photonics in the future.
Modeling the atrial fibrotic structure of patients suffering from Atrial
Supervising Professor: Dr. Craig Henriquez, Professor of Biomedical
Engineering and Computer Science
Shravan Verma is a senior Pratt Fellow in Biomedical Engineering and is working to
model the fibrotic structure of the atria in the heart using electrograms from patients
suffering from Atrial Fibrillation. He has modeled algorithms to detect the presence of AF
based on dominant frequencies using signal-processing techniques. Currently, he is
studying the causes of fractionation in AF electrograms and using that to relate it to the
underlying fibrotic structure. To do this, he is using Cardiowave, a modular simulation
system for Biodomain equations, in order to create a computer model that will behave
electrically similar to a human heart during AF. The causes and mechanism of atrial
fibrillation are not well understood; therefore, the methods of treatment are not very
efficient. Knowing the structure of the atria, a cardiologist will be able to conduct timely treatment of AF knowing the best approach to enter and the exact sites that need to be ablated using radiofrequency or any other method that may be suitable.
Shravan Verma’s Pratt Fellows Advisor is Dr. Craig Henriquez, Professor of Biomedical
Engineering and Computer Science at Duke University. Shravan will be applying to
medical schools for an MD, and hopes to continue research work in the field of cardiac
Aeroelastic Study of a Folding Wing Configuration Using Component Modal Analysis
Supervising Professor: Dr. Earl Dowell, William Holland Hall Professor of Mechanical
Engineering, Dean Emeritus
A folding wing is a wing configuration consisting of multiple segments, where the angle
between any pair of adjacent segments can change during flight. A previous Pratt Fellow
(Sebastian Liska) has analyzed a simplified folding wing using a continuum model. This
project analyzes the aeroelastic instabilities of a folding wing using component mode
analysis, allowing us to initially analyze the two halves of the wing as separate parts
using relatively simple equations of motion, and then combine the two parts using constraint
functions. Consequently, the analysis takes on a modular approach, where additional
complexities to the system will be added into the model as needed without rederiving existing
equations of motion.
The aeroelastic instabilities in question are divergence - a positive feedback between lift
and wing rotation that leads to failure, and flutter - a dynamic instability where oscillation
of wing grows in amplitude. The analysis involves determining the kinetic and potential
energies of the entire system, as well as calculating the work due to aerodynamic forces.
Three aerodynamic models, steady, quasi-steady, and Theodorsen’s unsteady theory, have been
implemented. The results match very well with Liska’s continuum model for all cases considered.
Design is underway for a flutter experiment for testing in the Duke University wind tunnel.
Future work includes incorporating a more accurate unsteady numerical aerodynamic model using
lattice theory, and improving understanding of the differences between different aerodynamic models.
Ivan is currently applying to graduate school and plans to complete a PhD degree in aerospace
engineering focusing on aeroelasticity.
Environmental Applications and Implications of Nanotechnology
Supervising Professor: Dr. Mark Wiesner, Civil and Environmental Engineering
Lauren’s work in the Wiesner group addresses the implications of nanomaterial release
into the environment. She studies the degradation byproducts of tetrahydrofuran in the
production of fullerene suspensions and is beginning a study on the interaction of
nanomaterials with nucleic acids. In her past semester in the Wiesner Group, Lauren has
studied the aggregation kinetics of nanoparticles in natural waters collected from the
Sandy Creek ecosystem, studied aggregation kinetics of nanomaterials in Bovine Serum, and
done work with contact angle measurements. Over the summer Lauren traveled to
Aix-en-Provence in France to work with members of the CEREGE Laboratory to learn about
X-ray Fluorescence Microscopy techniques, a technique that characterizes samples by
specific energies of fluorescence corresponding to atomic composition. Additionally,
Lauren is helping to develop a syllabus for an Environmental Nanotechnology course, which
Professor Wiesner hopes to teach in future semesters.
Microsphere Engineering: Optimization of Two-Phase Protein Dehydration Protocol
Supervising Professor: Dr. David Needham, Mechanical Engineering and Materials Science and Biomedical Engineering
Andrew Winslow is a Senior Pratt Fellow in Biomedical Engineering. His research focuses on the preparatory protein dehydration phase of his laboratory’s research interest in microsphere engineering for controlled drug delivery. Through a novel process known under his laboratory’s patent as “microglassification,” pure organic solvent is used to extract water from hydrated proteins, adequately preparing the proteins for storage. The importance to this dehydration method is that it offers a favorable alternative to the industry standard, a process limited by the reduction of protein content and conformational deactivation. While a measurable increase in protein activity and protein content versus the industry standard was observed under the current microglassification protocol, the less-than-ideal behavior of the dehydrated protein signaled room for improvement.
Andrew has begun a piecewise investigation of the individual components to his laboratory’s microglassification protocol. Among a slew of other parameters, his findings will delineate the drying solvent, saturation fraction, temperature, mixing method, and excipient which universally yield high retention of activity and content in microglassified proteins. Together, these individual parameters will comprise a dehydration method with a potentially revolutionary impact on the manufacture of biopharmaceuticals.
In his future, Andrew hopes to pursue an M.D. and begin practice as a physician investigator. His interests in medicine include anesthesiology and radiology. Aside from his Pratt Fellowship, his research interests include optical instrumentation and pharmacology.
Determination of tissue stiffness from on-axis displacement in Acoustic Radiation Force Impulse
Supervising Professor: Dr. Kathy Nightingale, Biomedical Engineering
Duo Xu is a Senior Pratt Fellow in Biomedical Engineering studying the dynamic response of tissue excited by Acoustic Radiation Force Impulse (ARFI). Currently, the lab carries out shear wave speed determination to assess tissue stiffness. David is developing and validating a method that uses displacements directly down the propagation axis (at lateral position of zero only), to determine tissue stiffness. The methods include using computer generated finite element models of tissue behavior to simulate the same physical phenomenon and circumstances that actually exist in ARFI, and comparing experimental datasets to this simulation to assess stiffness. The goal of the project is to determine tissue elasticity with greater sensitivity, less risk of tissue heating, and with faster acquisition times.
David's future plans are to go to medical school while continuing research in biomedical engineering.
Improving Cell Viability in 3 Dimensional Engineered Cardiac Tissue
Supervising Professor: Dr. Nenad Bursac, Biomedical Engineering
3-dimensional cardiac tissue constructs are widely believed to be superior to the traditional 2-dimensional tissue monolayers in terms of construct functionality. However, low cell viability in the centre of 3D constructs has limited the uses of thick bioengineered tissue in cardiomyoplasty. Lin Yang, a senior Pratt Fellow, is investigating the possibilities of depressing cell metabolic pathways in cardiac cells to reduce cell death in the ischemic and nutrient starved core of 3D constructs. She will first verify cell viability in the 3D cardiac constructs using various biochemical assays, and then test the effects of several drugs on cell metabolism and the live/dead cell ratio. She is currently optimizing procedures for making 3-dimensional, thick fibrin hydrogels and the Lactate Dehydrogenase (LDH) assay. She is also looking into the spatial distribution of cells in the hydrogel. Lin hopes to make progress in extending the life of gel-encapsulated cells. This will be a step towards improving the success rates of tissue graft treatment.
Lin’s advisor is Dr. Nenad Bursac Associate Professor of Biomedical Engineering at Duke University. She plans to continue her research in tissue engineering at the graduate school level.