The 18th Annual
NC State University
Undergraduate Research Symposium
Engineering and
Technology
Abstracts
Abstracts
are listed in alphabetical order by the last name of the corresponding author.
- Biological Sciences abstracts
Applied Sciences (Crop, Poultry, Animal, and Horticultural Sciences)
Ecology, Environmental, Conservation, Botanical
Molecular, Biochemical, Genetics, Cell Biology
Zoology, Physiology, Behavior, Neurobiology
- Design abstracts
- Humanities, Social Sciences, Psychology abstracts
- Physical and Mathematical Sciences abstracts
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Allen, Elizabeth L. Cameron, Paul H. Stewart, David A. Mbaneme, Veronica |
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Department(s): |
Biological and
Agricultural Engineering |
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Research |
William F. Hunt,
III/Biological and Agricultural Engineering |
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Title of Presentation: |
Residential Green Design
and Development in Cary, NC |
Poor water quality and watershed
contamination are effects of rising urbanization and exponential population
growth. In efforts to reduce stormwater
surface runoff and treat point source pollution, stormwater engineering
techniques have been developed to reduce runoff and allow for contaminant
filtration. This project required
various stormwater BMPs to be researched and designed for a green contractor’s
newly renovated home that will double as a demonstration home for her business. The stormwater features were required to account
for the first flush depth of precipitation that falls onto the property, while
correcting ponding and erosion issues occurring on the property and fitting the
client’s specifications. Permeable
pavement, cisterns, and rain gardens are some of the most prevailing stormwater
treatment systems that may be utilized in residential areas and were mainly
researched. Numerous site visits were
made to assess design constraints such as soil type, topography, area, existing
pipes and water/electrical lines, precipitation, roof size and shape, amount of
sunlight, and tree root location. Client
specifications such as aesthetics, cost, and maintenance requirements were also
taken into consideration. The components
of each BMP were chosen based on these design constraints and research
conducted. A permeable pavement system,
three optional rain gardens, and two cisterns were designed to account for the
first flush depth of precipitation that falls onto the property. A cost analysis will be performed for each
design to treat the 75%-95% storms, which were calculated to range from
approximately 1.0" to 3.1" respectively. The final design will be discussed and
presented to the client to possess for future installation plans for the
remodeling of her yard. This project
aims to provide the groundwork for a landscape that will spark community
interest in environmentally conscious residential design.
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Beard, Rachel M. McCullen, Seth D. |
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Department(s): |
Biomedical Engineering |
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Research |
Laura I. Clarke/Physics Elizabeth G. Loboa/Biology |
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Title of Presentation: |
Effect of Electrical
Stimulation on the Osteogenic Differentiation of Human Adipose-Derived Stem
Cells |
Electrical stimulation is being
investigated as an alternate therapy for bone regeneration at bone non-union
fracture sites. The applications of low frequency AC electric fields have been
shown to enhance the differentiation of both mesenchymal and neuronal stem
cells by upregulation of specific tissue markers. Human adipose-derived adult
stem cells (hASCs) are an alternative stem cell recognized for their
multilineage potential and relative ease of retrieval. The goal of this study
was to evaluate the effect of electrical stimulation as hASCs underwent
osteogenic differentiation. Human ASCs were seeded directly onto interdigitated
electrodes (IDEs) and exposed to AC electric fields of 0, 1, 3, 5 V/cm at 1 Hz
for 4 hours per day up to 14 days. Human ASCs were analyzed on day 7 and day 14
for cellular viability, proliferation, and matrix mineralization. For all
treatments, hASCs were largely viable as determined through fluorescence
imaging using a live/dead cell viability kit. Cell proliferation was determined
by quantifying the DNA of the hASCs on the IDEs using Hoescht 33258 DNA binding
dye. Cell proliferation did not significantly vary between treatment groups or
between time points. Matrix mineralization was determined by quantifying
accreted Ca2+ using the Stanbio calcium kit. It was determined that the 1 V/cm
electric field significantly increased the amount of mineralized matrix,
suggesting that specific electric field treatments can enhance the osteogenic
process of hASCs compared to static controls. As hASCs underwent osteogenic
differentiation under electrical stimulation of 1 V/cm at 1 Hz, they produced
significant amounts of bone tissue markers needed for bone regeneration at
non-union fracture sites.
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Behrouzi, Aria M. |
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Department(s): |
Chemical Engineering |
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Research |
Steven Peretti/Chemical
Engineering Ratna Sharma/Biological
and Agricultural Engineering |
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Title of Presentation: |
Assessment of Miscanthus Grass for Optimized
Bioethanol Production |
The price volatility of
crude oil and our nation’s dependence on foreign oil are key reasons for
optimizing biofuel production from renewable sources such as miscanthus, a
perennial grass. Current methods for converting miscanthus into ethanol can
yield approximately 2.5x the amount produced from corn or switchgrass on a per
unit weight basis. Widely used chemical pretreatments need to be optimized for
individual feedstocks to maximize lignin and hemicelluloses solubilization and
enhance subsequent conversion of cellulose to fermentable glucose. Lignin,
which accounts for a significant portion of the miscanthus composition, is
unusable for the production of ethanol and is often burned as an energy source.
This study investigated pretreatment methods to prepare miscanthus for improved
enzymatic digestibility and higher fermentable sugar yields. Assessed
pretreatment methods included NaOH (0.5%, 1 %, 1.5% w/w) and H2SO4 (0.5%, 1%,
1.5% w/w). All trials were carried out using feedstock comprised of miscanthus
species grown at the NCSU research farm in Williamsdale, NC, including Miscanthus giganteus, a sterile hybrid
of M. sinensis, and M. sacchariflorus, which is commonly
found in Europe. Based on analysis of data for lignin reduction, solid recovery
and sugar availability in pretreated samples, it was observed that 30 min/0.5%
and 60 min/1.5% acid and alkali pretreatments are promising, however hydrolysis
by enzymatic digestion is necessary to identify optimal conditions. Further
investigation will focus on employing cellulolytic enzymes such as cellulase
and β-glucosidase to analyze breakdown of polymeric cellulose chains to
glucose followed by fermentation of sugars to bioethanol by Saccharomyces cerevisiae or Zymomonas mobilis. Pretreatments
combining NaOH and H2SO4 for improved conversion will also be evaluated. The
results of this study can help in establishing a process for sustainable
biofuel production that lessens our dependence on foreign crude oil.
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Brannan, Ashley G. Sugimoto, Mark Nobles, Jeremy Madzivanyika, Collen Cumberland, Riley |
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Department(s): |
Nuclear Engineering |
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Research |
Jacob Eapen/Nuclear
Engineering K. L. Murty/Nuclear
Engineering |
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Title of Presentation: |
Feasibility of Hydrogen Production with Nuclear
Energy |
Nuclear energy is considered
as a viable source for the production of hydrogen. There are several ways of
producing hydrogen such as electrolysis, nuclear-assisted methane cracking and thermochemical
water cracking. It remains a challenge however, to optimize the performance of
nuclear reactors while taking into consideration environmental impact,
sustainability, and safety of hydrogen production. This project aims to prove
the feasibility by examination of conditions at which such a system will be
able to meet these challenges. The
project will entail a comparative analysis of current and future energy
needs,water resources and constraints, hydrogen production techniques, reactor
types, coolant and material selection, thermal-hydraulic design of core (to
meet Generation IV passive safety requirements), and economics of energy and
hydrogen production. The end result is a feasibility study followed by design
recommendations.
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Butler, Andrew B. |
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Department(s): |
Mechanical & Aerospace
Engineering |
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Research |
M. K. Ramasubramanian /
Mechanical & Aerospace Engineering |
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Title of Presentation: |
Camless Variable Valve Timing |
Camless variable valve
timing is a relatively new technology so the amount of research and information
pertaining to this topic is fairly limited. However, from the advancing
technology of Honda’s Variable Valve Timing and Lift Electronic Control (VTEC) and
other mechanical variable valve timing (VVT) systems, the knowledge needed for
camless VVT can be adapted from these discrete VVT principles. Honda’s latest
variable valve timing and electronic lift control mechanism, the iVTEC, has the
ability to switch between three cam profiles depending on the rpm and load on
the engine. This system changes cam profiles from the use of synchronized pins
controlled and powered by electro-hydraulic pressure. However, the iVTEC design
has limited fuel economy and experiences optimum engine performance at only
three different engine speeds. On the other hand, camless VVT allows an engine
to experience maximum engine performance and fuel efficiency at each and every
rpm while following the same principles of the iVTEC. Instead of using multiple
cam shafts with synchronizing pins, we have designed a camless VVT that is
electronically operated by a microcontroller which will control the
electro-mechanical solenoid actuators. In theory, the greater the speed or
loading on an engine, the more an engine needs to be supplied with air. To test
this theory, we will connect one solenoid to each intake and exhaust valve that
controls the flow of air through the engine. Depending on the load and rpm of
the engine, the microcontroller will process the information given and uses
pulse width modulation (PWM) to actuate the solenoid valves. Various simulation
tools were used to compare the advantages of this design (camless VVT) versus
VTEC. Through these simulations, we will determine the PWMs that will be best
for each loading and engine speed pairs to achieve maximum engine performance
and fuel efficiency for the system. Based on the simulation results, we will
build a simple design in the future.
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Byrne, Jacqueline |
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Department(s): |
Biomedical Engineering |
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Research |
Roger Narayan/Biomedical
Engineering |
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Title of Presentation: |
Effect of Varying
Surfactant Concentrations on Drop Diameter in Small-Scale Micro Array
Printing |
Micro arrays are a medical
technology that utilizes biological material, such as antibodies or DNA, to
detect certain substances in blood exposed to the array. Printing protein
solution onto a surface often requires a surfactant to enable flow from the printer
to the surface. The size of the drop formed on the surface dictates the size of
the micro arrays. The benefit of smaller sized micro arrays is increased
accuracy of the reading through elimination of excess variables. Though
previous studies have researched the affect of glycerol surfactant
concentration on drop diameter on large-scale drops, small-scales have not been
examined. The goal of this experiment is to study the affect of glycerol
concentration on a pico-liter scale to see if the governing principles of
surfactant apply for both large and small-scale drops. This study utilizes the
Bioforce NanoEnabler System to print drops of 5 to 20 micrometers in diameter,
of Donkey Anti-Goat antibodies onto silane slides. The Donkey Anti-Goat
antibodies are in a solution of 0.15M NaCl, 10mg/mL BSA and 0.01% NaN3. The
glycerol concentrations tested are 0.5%, 1%, 2.5%, and 5%. Analysis of the
results is done by AFM, as this device has the ability to operate in fluids,
label-free detection, single molecule detection capability, and nanometer
spatial resolution.
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Daniel, Kevin M. |
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Department(s): |
Wood and Paper Science |
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Research |
Richard Venditti/Wood and
Paper Science |
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Title of Presentation: |
Production of Microfibrillar Cellulose for Use in
High Strength Biocomposites |
Cellulose is the most
abundant polymer on Earth and can be utilized to make high strength
biocomposites. These biocomposites can
potentially reduce the amount of non-sustainable materials used in the U.S.
such as polyethylene and polypropylene, also reducing the US dependence on
foreign oil. Microfibrillated cellulose
has exponentially more surface area than regular wood pulp fibers, resulting in
more bonding area and higher strength properties. The production of
microfibrillar cellulose using energy intensive methods can be improved by
selecting specific plant materials that are advantageous. These materials can then be subjected to
pretreatments to further reduce the amount of energy required to produce
microfibrillar cellulose. The energy intensive production of microfibrillar
cellulose for use in high strength biocomposites has not been examined for pulp
types other than fully delignified fibers. This project examines various pulp types
including bleached and unbleached fibers, hardwood and softwood fibers, high
lignin mechanical fibers, and fibers that have been through a harsh drying
process. Examining various pulp types
will potentially reveal new properties of microfibrillar cellulose and aid in
the development of innovative high strength biocomposites.
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Daniel, Roger E. Jones, Eric J. Sievers, Jessica L. |
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Department(s): |
Material Science and
Engineering |
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Research |
Mike Rigsbee Keith Dawes Lew Reynolds |
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Title of Presentation: |
Inclusion Analysis for Calcium Treated Grades of
Steel |
In the manufacturing of steel, cleanliness of the
molten steel is vital to controlling physical properties. Inclusions in the steel can lead to a number
of problems in every stage of the manufacturing process. Solid inclusions in the molten steel can lead
to clogging during casting and can adversely affect physical properties. Inclusions that form after solidification due
to micro-segregation can lead to problems during rolling of steel plate due to
their often lower melting temperatures.
Clogging during casting creates several problems and defects. Some of the major issues related to clogging
are loss of production for the plant, degraded product quality, and safety
concerns. The goal of this project is
to determine how sulfur levels in the steel change throughout the process, it
will be important to take many samples over the life of a heat from melting to
casting. This will show how the
inclusions in the steel are affected by the various cleaning processes or where
in the line of production inclusions are being created. Six samples have been collected from each run
throughout the melting and casting process.
Samples are characterized using optical and scanning electron microscopy
and electron dispersive X-ray spectroscopy.
Control of inclusion formation may lead to improved control of
chemistry, improved production process, and most importantly improved final
properties. Nucor’s desulfurization process appears to be effective,
but the stir process responsible for elimination of hard inclusions may require
improvement.
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Davis, Raleigh L. |
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Department(s): |
Chemical Engineering |
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Research |
Richard Spontak/Chemical
Engineering |
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Title of Presentation: |
Incorporation of Copper Phthalocyanine Nanoparticles into Poly(styrene-(ethylene-co-butylene)-styrene) (SEBS) |
A variety of technological challenges may be overcome
through the creation and study of thermoplastic elastomers (TPE) and their
resulting nanocomposites. TPEs are
versatile co-polymers which possess rubber-like (elastic) properties, as well
as thermoplastic properties, which allow the polymer to be melted, molded, and
recycled. The focus of this study is on
a particular TPE, poly(styrene-(ethylene-co-butylene)-styrene)
(SEBS) and attempts to incorporate nanoparticles into the polymer via
electrospinning and polymer casting techniques.
Electrospinning is a technique which utilizes an electric field to
produce a randomly oriented, fibrous mat of dried polymer, with fiber diameters
ranging from the nanometer to micron scale.
Nanoparticles such as carbon black and copper phthalocyanine can be
dispersed into a polymer during electrospinning, thus altering the mechanical
and conductive properties of the polymer and creating a wealth of potentially
advantageous properties in a polymer fiber system. This study shows that thus far, success in
electrospinning SEBS has been limited due to the absence of a strong co-solvent
candidate, but through other nanoparticle dispersion techniques, particularly
melt mixing, nanoparticles can be successfully dispersed in SEBS. This study discusses the observed affects of
incorporated copper phthalocyanine nanoparticles on SEBS’s dielectric and
mechanical properties, as well as methods to improve the electrospinnability of
SEBS.
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Draelos, Mark T. |
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Department(s): |
Electrical and Computer
Engineering |
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Research |
Edward Grant/Electrical
and Computer Engineering |
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Title of Presentation: |
Artificial Antenna Tactile Sensor |
Antennae are a common type of
sensory apparatus seen in nature. Insects such as cockroaches are able to use
antennae to infer much information about their surroundings, including wind
direction and characteristics of the surface that their antennae contact.
Biomimetic sensors based upon insect antennae have potential for use in a wide
range of applications and can be built inexpensively. Following similar techniques described in
literature, antenna tactile sensors were constructed by gluing a single
fiber-optic cable strand onto the diaphragm of electret microphones. This
construction causes any stimulus applied to the antenna to be transmitted to
the diaphragm of the microphone. The resultant electrical signal produced by
the microphone was then analyzed to extract encoded information about the
antenna stimulus. Signal features as determined using the discrete Fourier
transform could then be matched to characteristics of the original stimuli,
such as the stimulus angle in the plane of the diaphragm and the stimulus force
or strength. Asymmetry inherent in the microphone or introduced by the gluing
of the fiber-optic cable strand gave rise to signal features from which
stimulus angle could be deduced whereas the power of the signal was related to
the stimulus strength. This presentation
explains the success achieved in inferring the angle and force characteristics
of an unknown stimulus from the signal produced by the microphone by matching
signal features against library of signal patterns from known stimuli.
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Dunn, Susan |
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Department(s): |
Civil, Construction, and
Environmental Engineering |
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Research |
Joel Ducoste/Civil,
Construction, and Environmental Engineering |
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Title of Presentation: |
Determination of a Collimated Beam Design for
Ultraviolet Light Emitting Diodes (UV LEDs) |
Disinfection is an important process in drinking
water treatment for the removal of harmful microorganisms. Ultraviolet (UV) light is becoming a popular replacement
for the standard method of chlorine disinfection, as UV is not known to produce
harmful disinfection by-products and can inactivate chlorine-resistant
organisms. Ultraviolet light emitting diodes (UV LEDs) that emit UV radiation
in the required wavelength for inactivation of microorganisms have become
available. UV LEDs are thought to have a longer lifespan and consume less
energy than low pressure mercury lamps, the typical UV disinfection lamp
technology. The objective of this project was to design a bench scale
collimated beam apparatus to determine the response of microorganisms to UV
LEDs. The collimated beam apparatus was
designed for optimal microbial inactivation by determining the spatial layout of
UV LEDs, distance from UV LEDs to sample, and number of UV LEDs. COMSOL Multiphysics, a computer modeling
program, was used to predict the results of a collimated beam study. Computer simulated Layouts with four and
eight UV LEDs were analyzed for Petri factor and peak irradiance. The results
show that 6 cm is the minimum distance that will meet the desired Petri factor
of 0.900 for the majority of UV LED layouts.
For a four UV LED system, UV LEDs placed in a diagonal array in the
center of the plane produced a Petri factor of 0.909 and a peak irradiance of
0.012 mW/cm2. For an eight UV LED system, UV LEDs placed in a 4x2 array in the
center of the plane produced a Petri factor of 0.903 and a peak irradiance of
0.025 mW/cm2. The results of this
numerical study will be used to build a collimated beam and full scale UV LED
reactor for point source disinfection.
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Earley, Kathryn E. Jafarpour, Farshid Rose, Corinne E. |
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Department(s): |
Chemical and Biomolecular
Engineering Nuclear Engineering |
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Research |
Mohamed Bourham/Nuclear
Engineering Lisa Bullard/Chemical and
Biomolecular Engineering |
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Title of Presentation: |
Magnetic Separation in Zero Gravity |
Interest in space exploration and related
technologies is on the rise. Long-term manned
space missions are on the horizon, and as the range of activities in
microgravity diversifies as expected within the next few decades, engineers
will be faced with new technological challenges. Virtually hand-in-hand with any manufacturing
process is the need to continuously separate mixed fluids in pipes, yet all
conventional separation processes depend upon separation by fluid density
whereby lighter fluids separate out from heavier fluids due to gravity.
Centrifugation is a viable separation solution in some cases, but this batch
process has the drawback of low throughput and the development of an angular
momentum that can affect spacecraft trajectory.
The NCSU CHE Zero-G team designed a continuously operating phase
separation process that can function in reduced gravity or in normal
gravitational environments through the application of a magnetic field. Initially, the team planned to test the
design in microgravity through NASA’s Microgravity University program; however,
due to decreased funding, the design was modified and will be tested on the
ground. Two-phase separation will be
accomplished in the magnetic chamber, a clear pipe surrounded by two copper
coils. The design implements a
magnetized magnetohydrodynamic fluid that is attracted to areas where the
magnetic field gradient is the largest within the constructed magnetic
mirror. Thus, the air in the system is
forced to the annular space within the pipe.
Collection tubes are strategically placed around the chamber to
physically separate the immiscible phases.
Optimal process parameters are controlled and maintained by an
air-syringe system through which air content in the system can be increased and
an iron microparticle trap that will allow variance in iron microparticle
concentration.
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Student
Author(s): |
Earley, Kathryn E. Roskov, Kristen E. |
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Department(s): |
Chemical and Biomolecular
Engineering |
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Research |
Richard J.
Spontak/Chemical and Biomolecular Engineering |
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Title of Presentation: |
Electrospinning Nanostructured Organometallic
Polymer Systems Containing Magnetically-Active Nanoparticles or
Poly(ferrocenylsilanes) |
Electrospinning is a useful production method used to
create continuous polymer fibers with controllable diameters for applications
in tissue engineering, protective clothing, and sensors. Once inorganic
additives (i.e. carbon nanotubes, micelles, and nanoparticles) are added to the
polymer system, qualities such as functional strength, biofunctionality,
conductivity, or magnetism can be enhanced. Organometallic polymer systems used
in this research contained either magnetically-active nanoparticles or poly(ferrocenylsilanes) (PFS). These materials were electrospun
in order to investigate the relationship between solution and processing
parameters on fiber morphology. This research was intended to provide a better
understanding of how inorganic additives affect fiber properties. Poly(2-vinyl pyridine) (P2VP) was tested for its
electrospinability in several solvents (i.e. dimethylformamide (DMF) and
chloroform) at different concentrations. PFS-containing block copolymers have
been shown to produce micellar morphologies such as cylinders, tubes, fibers,
and tapes. By utilizing a corona-selective solvent, the micelles can form
morphologies with an iron-rich core of PFS. In these experiments cylindrical
micelles of lengths greater than one micron were found to form. These micelles
were then blended with P2VP homopolymer and electrospun. Scanning electron
microscopy (SEM) images supported the conclusion that these micelles reinforced
and strengthened the polymer fibers and produced less bead defects. Another
research objective was to expand upon the Spontak groups’ previous
investigation of the inclusion of iron oxide nanoparticles into polymer
solutions. Polymer systems included P2VP, poly(caprolactone)
(PCL), and poly(ethylene oxide) (PEO) in addition to three different diameters
of iron oxide nanoparticles. Both the nanoparticle size and polymer to
nanoparticle ratio were systematically varied to determine if these parameters
affect the morphology or nanoparticle distribution. It was determined that the
distribution of nanoparticles was not dramatically affected by the loading
ratio and that the inclusion of nanoparticles resulted in instabilities in the
jet which led to electrospraying in addition to electrospinning.
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Grismer, Dane A. |
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Department(s): |
Wood and Paper Science |
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Research |
Joel J. Pawlak/Wood and
Paper Science |
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Title of Presentation: |
Characterization of Starch Microcellular Foam
Particle Formation |
Starch is a naturally occurring carbohydrate made of repeating
glucose sugar units. Starch derived materials have the potential to replace
many non-sustainable materials used in a wide-range of consumer
applications. A procedure has been
developed to consistently produce starch microcellular foam (SMCF) particles
made with native corn starch. Water was exchanged out of cooked starch with
incremental additions of ethanol under vigorous mixing. In order to
characterize particle formation, samples were diluted to a set percentage of
starch solids and tested for turbidity. Turbidity is a measure of light
scattering caused by the cloudiness of a solution, or solids suspension, and
indicates the presence of a foam. Turbidity values were plotted against the
ethanol percentage at which they were tested. Along the curve of increasing
ethanol percentage, turbidity rapidly declined with initial addition, leveled
off around 30 percent ethanol, and then began to increase near 70 percent
ethanol. This behavior shows that formation of SMCF particles is not linear
with the addition of ethanol. The turbidity of ethanol-water mixtures were
tested and showed that there was no turbidity dependence on the percentage of
either ethanol or water in the solution. No significant time-dependence was
shown for turbidity readings for at least the first two hours after a sample
was taken, though all samples were measured within 15 minutes of the time they
were taken.
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Hicks, Justin |
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Department(s): |
Biomedical Engineering |
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Research |
Peter Mente/Biomedical
Engineering |
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Title of Presentation: |
In Vitro Biomechanical Comparison of Internal
Spinal Fixation Techniques on the Canine Lumbosacral Vertebrae |
Spinal fixation is commonly used in small animal
surgery for traumatic injuries to the canine lumbar vertebrae. In patients with
unstable spinal injuries surgical intervention is often promptly needed to
prevent further neurologic damage by reestablishing anatomical alignment,
addressing spinal cord compression, providing rigid stabilization of affected
vertebrae and relieving or moderating pain. Several surgical techniques have
been described, among those, internal and external fixation. An optimal
configuration or system of fixation has yet to be determined. The two fixation
techniques that are mostly used and clinically accepted utilizes: 1) positive
profile threaded pins and polymethylmethacrylate (PMMA) to form an internal
fixator bridging the unstable lumbosacral spine segments or 2) bilateral
transarticular screws. A recently developed SOP™ Locking Plate System offers
many advantages and unique abilities when compared to the conventional approach
in spinal fixation. The SOP system is intended to allow locking screw
technology using standard orthopedic screws but since the plate can be
contoured to any shape, the locking screws can be positioned in a variety of
orientations. The SOP™ system was designed to be significantly stiffer and
provide more stable fixation of fractured fragments with compromised bone
quality than comparable compression or locking plates. The system has a smaller
footprint than standard orthopedic plates and pins/PMMA internal fixation. The
purpose of this canine cadaver study is to evaluate the biomechanical
characteristics of the canine lumbosacral spine in flexion and extension via
four-point bending test using three different types of internal fixation
techniques. 1) Basic 6-pin system; positive profile threaded pins and
polymethylmethacrylate; 2) bilateral transarticular screws and 3) SOP™ Locking
Plate System.
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Hook, David H. Chan, Ryan N. Powell, Javon Wong, Patrick Z. |
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Department(s): |
Materials Science and
Engineering |
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Research |
Keith Dawes/Materials Science and Engineering Jon-Paul Maria/Materials
Science and Engineering |
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Title of Presentation: |
High Temperature, Thin-Film Thermocouples |
This project will attempt to create a thin film
thermocouple from Indium Tin Oxide (ITO) that operates at high temperatures. A
thermocouple is a temperature sensor which bases readings on a measured
potential difference, based on the Seebeck principle. The premise of this work
is to use the unique electrical properties of ITO to create a junction voltage
based on a stark tin concentration difference over an interface. The samples
used for these experiments will be generated using sol-gel deposition, which is
a wet chemistry technique for creating thin films. Controlling deposition
parameters yielded marked differences in electrical properties of produced ITO
thin films. Resistivity values of approximately 7x10^-3 Ω-cm to 7x10^-2 Ω-cm have been recorded. Difference in resistivities implies a differnce
in Seebeck coefficients, and interfacially combining two layers of ITO with
different Seebeck coefficients should theoretically result in a robust,
thin-film thermocouple.
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Jackson, Lauren C. Bender, Brian F. Tung, Toby V. |
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Department(s): |
Materials Science and
Engineering |
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Research |
Keith Dawes/Materials
Science and Engineering George Rozgonyi/Materials
Science and Engineering |
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Title of Presentation: |
Reactive Ion Etch Optimization for Polysilicon on
MEMS Devices |
The primary objective of this project is to develop
an etching and cleaning process that can be used to reduce the occurrence of etch-related
defects in polysilicon microelectromechanical (MEMS) devices. MEMS combine
electrical and mechanical components with a length scale between 1 μm and 1 mm on an integrated circuit platform. MEMS
are incorporated into numerous applications including biomedical sensors,
microphones in mobile technology, and actuators for energy harvesting. The
industry standard for producing MEMS includes Reactive Ion Ethcing (RIE), which
is the selective vertical removal of material. The primary goals of processing
MEMS device trenches are achieving vertical sidewalls and minimizing
micromasking during etching. Non-vertical sidewalls can inhibit the ability of
subsequent layers to adhere and limit the mechanical functionality of a MEMS
device. Micromasking from redeposition of etched material can result in
post-etching debris that can short out MEMS devices and inhibit mechanical
motion. Optimization of the Bosch RIE process for polysilicon substrates will
increase the quality of sidewalls, minimize effects of micromasking, and
achieve a desirable surface smoothness. The Bosch RIE process for etching
polysilicon has been optimized by varying the ratio of C4F8 to SF6, source
power, and bias power. The combination of parameters was determined using a
Box-Behnkin DOE. The Alcatel DRIE in the NCSU Nanofabrication Facility was used
to perform the etching. Each sample was analyzed with SEM analysis for vertical
sidewalls and surface defects. The
processing problem was presented by MEMSCAP of the Research Triangle Park. MEMSCAP
provides funding for this Materials Science Senior Design project.
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Kennedy, Chris B. |
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Department(s): |
Nuclear Engineering |
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Research |
Steven Shannon/Nuclear
Engineering |
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Title of Presentation: |
Study of Low Density, Low Temperature Plasmas
Containing Non-Maxwellian Electron Energy Distribution Functions Using Novel
Langmuir Probe Analysis Techniques |
Understanding low temperature plasma chemistry is a vital
component for advanced materials fabrication for energy applications, computer
technology, and other high interest research fields. Because low temperature
plasmas behave differently from the assumed Maxwellian electron temperature
distribution and because these distributions determine plasma chemistry,
improved measurement of these distributions is desirable. Current methods for
resolving the electron energy distribution function (EEDF) involve taking the
second derivative of raw data with the assumed Maxwellian shape function. Using
novel Langmuir probe analysis techniques by means of a generic step function
combined with Tikhonov regularization, an alternative method to the inverse
problem is achievable that greatly improves the accuracy and range of energies
over which an EEDF can be measured. Collaboration with the University of Kansas
(KU) provides our theoretical experiment with raw data from multiple plasma
runs for BCl3, SF6, N2, and He for plasma processes under development for
advanced microelectronic fabrication technology. The provided data consists of
power and pressure sweeps in BCl3, and concentration comparisons between BCl3
and both SF6 and N2. The extracted electron current is run through the
developed MATLAB algorithm to extract EEDF. The resolved EEDF curves are
processed in two manners, first by comparing the EEDF to the EEDF obtained by
KU, and second by performing a sensitivity study of the algorithm to changes in
the plasma potential, pressure, and power. Results of the methodology suggest
relative immunity to noise, sensitivity to the number of raw data points, and
sensitivity to the parameter, a. Future work and goals would be to reduce
method sensitivity and to convert the algorithm to an automated web-based
application.
|
Lada, Carissa L. Pierce, Jonathan R. Harris, Joshua S. |
|
|
Department(s): |
Materials Science and
Engineering |
|
Research |
C. Maurice Balik/Materials
Science and Engineering Keith Dawes/Materials Science
and Engineering |
|
Title of Presentation: |
Improving Tracking and Erosion Resistance
Performance of Raysulate Formula T277 |
The objective of this research was to improve the
performance of a polymer formulation in high-voltage Tracking and Erosion
Resistance Testing (TERT). The base
resins for this compound are linear low density polyethylene (LLDPE) and EPDM
rubber, which are combined with additives that improve TERT performance, promote
radiation crosslinking, and prevent UV damage.
Variations of this polymer formulation are used as insulating covers for
switchgears, busbars, overhead lines, substations, etc. The predominant failure mechanism for these
products in the field is tracking due to dry band arcing. Important properties considered were thermal
conductivity and hydrophobicity. To
control these properties, additive compositions were manipulated, including
aluminum trihydrate, alumina, and silicone oil.
It was shown that adding 2% alumina to the current formulation improved
TERT performance, and decreasing the current composition of aluminum trihydrate
from 42% to 25% improved TERT performance in samples of the LLDPE and EPDM
rubber resin. Due to the nature of the
test, the results for silicone oil were not considered conclusive.
|
Leotaud, John A. |
|
|
Department(s): |
Biomedical Engineering |
|
Research |
Gregory S.
McCarty/Biomedical Engineering |
|
Title of Presentation: |
Single Nucleotide Polymorphism Detection and
Characterization Using Surface Enhanced Raman Spectroscopy |
All our genetic information is contained in sequences
of DNA nucleotides. Mutation of this DNA
sequence, no matter how small, can cause very harmful diseases. These diseases
include sickle-cell anemia, cystic fibrosis and hemophilia. There are current
detection schemes for DNA mutations but these can be extremely costly, as well
as inefficient. Because of this, scientists all over the world are attempting
to find a novel alternative. Surface Enhanced Raman Spectroscopy has been used
here for the detection and characterization of single nucleotide polymorphisms
and polymorphic regions within DNA oligonucleotides. Raman spectra were
collected, analyzed and compared for differences between DNA helices formed
from complimentary oligonucleotides, those with 1 mismatched base pair, those
with 3 mismatched localized base pairs, and those with 3 mismatched base pairs
which are delocalized. Raman spectra obtained in these experiments showed
differences for the four cases. The results were assessed in terms of DNA helix
or duplex formation based on the theory that base mismatches will interfere
with proper helix formation and will result in a decreased hybridization and
decreased Raman intensity. These spectra differed mostly in intensity but also
in Raman shift. The spectra obtained for the 1 mismatch was significantly
higher in intensity than those for the 3 mismatched. The spectra for the
polymorphic regions with three localized mismatches were much higher in
intensity than those gotten for the delocalized. The localized mismatches can
form a tighter helix at all other regions along the chain besides this region
of mismatches known as the polymorphic region (PR). The delocalized mismatches
however have more points at which the helix or duplex will not be able to form.
|
Lewis, Nicole M. |
|
|
Department(s): |
Mechanical and Aerospace
Engineering |
|
Research |
Stefan Seelecke/Mechanical
and Aerospace Engineering |
|
Title of Presentation: |
Development of an In-situ Video-Based Monitoring
System for Stent Deformation and Migration Mechanisms |
An abdominal aortic aneurysm (AAA) is an extremely
dangerous condition that is usually treated by a stent inserted into the
aneurysm during surgery. Although most of these operations are initially
successful, there are several problems that may occur post operation, including
leaks, stent migration, and fatigue failure (as detected by a CT scan). Doctors
are unsure about the nature of the stent failures since they cannot be observed
on a daily basis. To determine the mechanism(s) of failure of these stents, an
experimental set up was designed to continuously study the behavior of a stent
inside an aneurysm over an extended period of time. The system is built around
a transparent AAA replica made from silicone material with life-like mechanical
properties (collaboration with Dr. Harrysson, ISE). It contains a pump system
that--using a water/glycerine solution--produces realistic blood pressure
waveforms and stroke volume for a number of scenarios, e.g, regular blood
pressure or hypertension under rest conditions or accelerated rates. It is also
equipped with video recording devices that monitor and record the behavior of
the stent inside the aneurysm. This system will enable testing of synthetic
aneurysms constructed from actual patient scans as well as a systematic study
of migration mechanisms for varying geometries, e.g., neck angles and healthy
artery neck length, to establish quantitative failure criteria. The results
from this research project will help explain to doctors why the stents in the
abdominal aorta shift and fail over time as well as assist them in their choice
of the most suitable stent type prior to surgery. In the future, reliable quantitative computer
prediction models can be generated from the results of these experiments. With
such capabilities, it is envisioned that someday custom-built stents, optimally
designed for a specific patient, will be manufactured just-in-time.
|
Lohmeyer, Whitney |
|
|
Department(s): |
Mechanical and Aerospace
Engineering |
|
Research |
Fred R.
DeJarnette/Aerospace Engineering |
|
Title of Presentation: |
New Method for Calculating Skin Friction at
Transition from Laminar to Turbulent Boundary Layers |
Through the analysis of skin
friction on a flat plate in incompressible flow, hot spots are found to occur
when the skin friction at the transition from laminar to turbulent boundary
layers is calculated to be higher than the value of the traditional method of
calculating skin friction of the turbulent boundary layer at transition.
Prandtl introduced the traditional method by assuming the virtual origin of the
turbulent boundary layer existed at the leading edge. Several authors later
introduced a modern method, which assumes the boundary layer thickness to be
continuous at the transition point and obtains a virtual origin between the
leading edge and the transition point. By integrating the integral form of the
momentum equation a new method is formed, and proves that the momentum thickness
of the laminar boundary layer should be equal to the momentum thickness of the
turbulent boundary at the transition point, and a new virtual origin for the
turbulent boundary layer is found. Compared to the modern method, the use of
the new method more accurately predicts heating rates, reducing the number of
hot spots, and therefore eliminates unwanted cost and weight to in turn improve
the overall performance of the spacecraft.
|
Majikes, Jacob |
|
|
Department(s): |
Chemical and Biomedical
Engineering |
|
Research |
Richard J.
Spontak/Chemical and Biomedical Engineering |
|
Title of Presentation: |
Permeability of PET and Recycled PET Nanocomposites |
Polyethylene Terephthalate (PET)
is common in industry due to its desirable mechanical and barrier
properties. These properties allow it to
be used for many applications ranging from plastic bottles, to packaging and
various adhesive tapes. While PET is
also one of the easier thermoplastics to recycle, it's properties are
greatly reduced after moving through the recycling process, due to accumulated
impurities and defects. Of the
properties affected, the surface chemistry, mechanical properties and
permeation have the most impact on the use of recycled PET in the bottling
industry. Improving these properties
during the recycling process would increase the cost efficiency of PET
recycling as a whole. To this end, we
created PET/Clay nanocomposites. In the
nanocomposite, the clay should help act as a barrier for gases, and increase
the mechanical strength of the PET.
Virgin PET, recycled PET, and nanocomposites of both containing 5% by
weight clay were ball milled for time periods ranging from 2-15hrs, pressed
using a hot press, and tested in a permeation cell for their permeability
values. Helium gas was used at 100 PSI
in the permeation cell. We predict that
the permeability will decrease when the clay nanoparticles are introduced, and
that the PET will have a lower permeability than the recycled PET.
|
Mbaneme, Veronica |
|
|
Department(s): |
Biological and
Agricultural Engineering |
|
Research |
Mari S. Chinn/Biological
& Agricultural Engineering |
|
Title of Presentation: |
Production of Cellulase
Enzymes in Solid Substrate Cultivation for the Conversion of a Paper Based
Cellulosic Substrate to Fermentable Sugars |
The production of fuels and high value chemicals from
renewable resources is a significant research area with efforts focused on
reducing US dependency on fossil fuels and enhancing environmental and economic
sustainability. This project contributes
to this effort through the examination of a paper-based cellulosic
substrate. The substrate in combination
with the solid substrate fermentation (SSF) technology has the potential to
provide high activity cellulases at low cost, relative to commercially
available enzymes, for the conversion of biomass to simple sugars and
subsequent fermentation to high value products like ethanol and amino
acids. The objectives of this research
project were to 1) investigate the extent of digestibility of the substrate at
various substrate (1%, 2.5%, 5%, and 7.5% w/v) and commercial cellulase enzyme
loading rates (7.5, 15, 30, and 60 FPU/g air dry substrate of endo,
exo-glucanase, with corresponding beta-glucosidase at 12.5, 25, 50, and 100
CBU/g air dry substrate), and time intervals; and 2) evaluate salt
supplementation in SSF of a paper based substrate on cellulases produced by two
Trichoderma reesei strains. The 60/100
FBU/CBU per gram enzyme loading rate performed the highest in producing a
change in reducing sugars, giving a range of 61 to 199 mg glucose/g substrate
for 1%, 2.5%, 5%, and 7.5% w/v substrate loading rates at 48 hours. However, amongst all treatments, more than
half of the available substrate was not converted to reducing sugars, which may
be a result of inhibition effects. SSF
experiments were conducted utilizing T. reesei MCG77 and T. reesei QM9414. The need for additional nutrient sources were
evaluated by looking at differences in cellulase and product formation between
experimental samples with and without salts included for 9 days. Growth of the fungi species seemed to improve
with the addition of salts. The enzymes
produced in SSF were extracted and measured using a filter paper assay. It is anticipated that the activity of
cellulase will be associated with growth.
Moving forward, the effectiveness of SSF produced enzymes will be
compared to the current commercially available enzymes.
|
Medda, Suman |
|
|
Department(s): |
Biomedical Engineering |
|
Research |
Roger Narayan/Biomedical
Engineering Shuan Gittard/ BIomedical
Engineering |
|
Title of Presentation: |
Fabrication of a Middle Ear Conductance Testing
Apparatus |
A testing apparatus was developed to measure sound
conductance in middle ear prostheses. Dimensions of the apparatus were chosen
to model those of the inner ear canal. Two membranes compress the prostheses.
An audio speaker provides the stimulation and a touch microphone combined with
an FFT analyzer were used to obtain conductance data. The apparatus will be
used to compare commercially and non-commercially available middle ear
prostheses. The device will aid in the development of novel middle ear
prothesis designs with features to improve function. Potential future uses of
this device are to test novel patient specific middle ear protheses fabricated
by laser-based rapid prototyping.
|
Miller, Tenea M. Alston, Britany P. Badawi, Steven M. Brim, Ruth E. |
|
|
Department(s): |
Biological And
Agricultural Engineering |
|
Research |
Ratna
Sharma-Shivappa/Biological And Agricultural Engineering |
|
Title of Presentation: |
Solar Powered Water Heater |
In an effort to use natural resources more
efficiently, solar powered instrumentation devices are being developed in many
different disciplines. Ideally, solar power is likely to assist with powering
large amounts of the world’s electrical needs in the future. Additionally,
water from a solar powered heater is generally used in household applications
such as laundering linens, bathing, washing dishes and cooking. To address the
need of solar water heating using indigenous materials, an inexpensive and
easily constructed water heating device was designed and fabricated. The system
is expected to provide domestic low income families with a cleaner, more
efficient and less expensive heating method to improve the quality of life. The
heating system consists of a solar collector and a water reservoir. It uses a
polypropylene glycol-water mixture as a means to transfer solar heat to the
water. The solar water collector has an aluminum case with aluminum c-channel
rod baffles to provide enough residence time for the water-glycol mix to absorb
heat. The system uses a car radiator as a heat exchanger in the water
reservoir. It is anticipated that this
system, will provide 40-70 percent of a household’s annual hot water need.
Testing the water heating capacity of the system at various fluid flow rates
can help assess this goal and evaluate efficiency. The designed system is
expected to be of use not only locally, as a pre-heater or heater, but as in
developing countries where electricity is not an easily accessible resource.
|
Rooks, Kenneth F. Dodd, Christopher B. Happel, Alec S. Kennedy, Christopher B. |
|
|
Department(s): |
Nuclear Engineering |
|
Research |
Hany Abdel-Khalik/Nuclear
Engineering Robin Gardner/Nuclear
Engineering |
|
Title of Presentation: |
Design of an Interrogation System for Nuclear
Proliferation Detection |
In the post-9/11 world, the proliferation and
smuggling of weapons of mass destruction, particularly nuclear weapons and
special nuclear material (SNM), is of vital importance to the national security
of the United States of America. As over
80 percent of cargo entering the United States arrives via seaports, shipped in
standardized cargo containers, the potential for smuggling is always a
possibility. A detection system capable
of detecting SNM in such containers would at worst provide an effective
deterrent to weapons proliferation, and at best interdict and severely impede
the flow of weapons-grade nuclear material into the country. The main problem with such a detection system
arises from the capability to shield all radiation from the isotope to be
smuggled to the extent that any detector is useless. Therefore, a layered approach is
proposed: first, the container is
scanned as it moves through an X-ray booth, then interrogated by nuclear
methods in a nuclear detection booth and finally by physical inspection if the
system detects a questionable trace. The
nuclear interrogation component utilizes a 14-MeV pulsed neutron source
underneath the container to induce fission of any fissile material in the
cargo. An array of neutron and gamma
sensitive detectors is employed above the container as the container travels
through the device. Fission events are
detected primarily through delayed neutrons and prompt gamma rays. The presence of any delayed neutrons
positively identifies the presence of SNM, while gamma spectroscopy is used in
order to identify the particular nuclide.
Design constraints of the system include dose limits to the container
contents, cost of the system, and time required to complete the scan. Analysis of the method indicate there is a
level beyond which no SNM can be detected, however the system will provide an
effective deterrent, making smuggling prohibitively difficult and
expensive.
|
Sadovy, Garik C. |
|
|
Department(s): |
Materials Science and
Engineering |
|
Research |
Yaroslava
Yingling/Materials Science and Engineering |
|
Title of Presentation: |
Behavioral Analysis of Oligonucleotides in DNA
Multilayer Films |
DNA thin films are applicable to a variety of uses,
including bio-functionalized sensor surfaces, diagnostics, and drug delivery vectors.
The stability and formations of these thin films is a critical part of the
development of these applications, and has been extensively studied1, though
quantitative analysis of the behavior of these films was previously
inaccessible to examination. Using molecular modeling simulations, we assessed
the probability of oligonucleotide crossovers and self-conformation occurring
in thin films incorporating homopolymeric oligonucleotide diblocks of varying
lengths (10, 20, 30, 40, 50, and 60 mers). It was found that 10mer films show
no crossover behavior, while 60mer films have a high probability of crossovers.
The behavior of oligonucleotide diblocks in varying positions relative to other
strands (either Thymine and Thymine or Thymine and Adenine interactions) was
also inspected for probability of crosslinking and self conformation. This work
holds implications in the formation of these films for the aforementioned uses
as well as in the stability of these films upon formation of advanced layers
and their exposure to varying environments. (1)
Lillian Lee, Angus P. R. Johnson, Frank Caruso. Biomacromolecules.
2008, 9, 3070-3078
|
Shearer, Kimberly L. |
|
|
Department(s): |
Chemical Engineering |
|
Research |
Saad Khan/Chemical
Engineering |
|
Title of Presentation: |
Electrospun Nanofibers of
Aliginates for Tissue Scaffolds |
Tissue Scaffolds are used in
biochemical engineering to provide a structure for cells to adhere to and
regenerate damaged tissue. Nanofiber
based tissue scaffolds, obtained via electrospinning, are getting prominence
because of their inherently small size scale that are conducive to increased
cell migration and accessibility to nutrients. In this project, we are
examining fundamental and technological issues related to electrospinning
alginate, a natural and biodegradable polymer. Despite the desirable attributes
of alginate, it canot be electrospun into nanofibers on its own. We are
therefore examining how addition of surfactants and a second polymer,
polyethylene oxide can be used to modulate to the viscoelasticity, conductivity
and surface tension of the solution to obtain nanofibers with controlled
properties. The effects of these parameters on fiber morphology and size, and
the underlying mechanisms will be discussed.
|
Sigmon, Jr., John C. |
|
|
Department(s): |
Biomedical Engineering |
|
Research |
Glenn Walker/Biomedical
Engineering |
|
Title of Presentation: |
Microfluidic Device for
Trapping and Studying Yeast |
The particle trapping mechanism is located within a
multi-layered microfluidic device made of a silicon-based polymer,
polydimethylsiloxane (PDMS). The bottom
layer is a glass cover slip, which is bonded to and lies underneath a PDMS
layer containing the microfluidic channel.
The channel is 100 micrometers wide and approximately 6 micrometers
high. Located in the middle of the
device along the channel is the particle trapping region. Bonded directly above this region is a thin membrane
of PDMS, which is to be actuated by a pneumatic valve. The top layer is bonded to this membrane,
which contains a valve that lies congruent with the trapping region. The
particle trapping mechanism is an effective means of keeping particles stagnant
while simultaneously applying fluidic stimuli.
Thus far, the device works very well with but is not limited to yeast
cells. The means of holding cells this
way and keeping most of their surface area exposed to stimuli is applicable to
a wide variety of biological experiments.
This allows for close monitoring of individual cells or particles over a
given time period of imaging. The
dimensions for the trapping mechanism can be modified for trapping particles of
various sizes. The device will trap yeast cells and expose them to a specific
concentration of a synthetic pheromone called alpha-factor. This will be administered over varying
amounts of time to promote a morphological mating process called shmooing. When the yeast cell detects the pheromone and
begins to shmoo, the cell is theoretically supposed to continue to switch
permanently. Controlling the duration of
alpha-factor impulse injections will allow for defining how long at what
concentration it must take to cause a cell to switch and if the cell is capable
of switching back when the pheromone is taken away.
|
Smith, Justin |
|
|
Department(s): |
Chemical &
Biomolecular Engineering |
|
Research |
Richard Spontak/Chemical
Engineering Kim Rasmussen/Theoretical
Division, Los Alamos National Laboratory |
|
Title of Presentation: |
Predicting the Phase Behavior of Solvated Triblock
Copolymers |
Block copolymers are one of the most ubiquitous classes
of polymers due to their inherent multifunctionality. These materials consist
of two or more homopolymers covalently linked together and, because of the
covalent linkage, spontaneously microphase-separate to form nanoscale domains
in the same fashion as small-molecule surfactants. More specifically, ABA
triblock copolymers with glassy A endblocks and a
rubbery B midblock are classified as thermoplastic elastomers due to their
ability to form an elastomeric network stabilized by physical crosslinks. Addition of a midblock-selective solvent to such copolymers induces
swelling and, under favorable conditions, phase transitions. Solvated
triblock copolymers are of commercial interest as vibration-dampening and
shape-memory media, and have recently been identified as high-performance
electroactive polymers. An important question that must be addressed relates to
the basic phase behavior of such multicomponent systems. Due to the large
parameter space available for designing such systems, we have elected to
develop a predictive methodology for elucidating the role of several important
parameters on the phase behavior of solvated triblock copolymers: (1) the
thermodynamic incompatibility of the copolymer, (2) the concentration of
solvent, and (3) the solvent quality. For this purpose, we have employed a
self-consistent field (SCF) model, which is capable of yielding
energy-minimized morphologies, to discern the order-order transition from a
lamellar to cylindrical morphology under systematically varied molecular
conditions.
|
Swindlehurst, Garrett R. |
|
|
Department(s): |
Chemical and Biomolecular
Engineering |
|
Research |
Orlin D. Velev/Chemical
and Biomolecular Engineering |
|
Title of Presentation: |
Encapsulation of Iron
Pyrophosphate Colloids in a Cellulose Microparticle Matrix |
Nutraceuticals recently have become a key area of
research interest at the intersection of colloid and food science. The combination of chemical nutrients and foods
in an effective and appealing package for consumers is a research priority in
this field. The encapsulation of iron
pyrophosphate nanoparticles in a hypromellose phthalate (HP-55) matrix using a
pH-controlled precipitation process was investigated. Iron pyrophosphate colloids and HP-55 solution
were premixed in a dilute aqueous solution and sheared at 1000 rpm. Dilute HCl solution was then added to the
mixture to bring the pH below 4, and HP-55 precipitated in amorphous
microparticle form to entrap suspended colloids. The colloids present in the supernatant were
then dissolved in a concentrated acid and ethylenediaminetetraacetic acid
(EDTA) solution at pH 1, and the concentration of iron was quantified using
UV-vis spectrophotometry. The calculated
total percentage of iron in the supernatant was 8.6% by mass, indicating that
89.9% of colloids were encapsulated.
Scanning electron microscopy (SEM) and transmission electron microscopy
(TEM) imaging confirmed that colloids were entrapped within the HP-55
matrix. Initial energy dispersive x-ray
spectroscopy (EDX) analysis suggested that encapsulation, by elemental
composition, was 100% efficient. These
initial results show the technique to be very promising for efficient creation
of composite nutraceutical delivery particles.
However, further characterization is required for conclusive results on
encapsulation efficiency. Several
theories are currently being investigated for the formation of “core-shell”
colloids consisting of iron pyrophosphate particles coated in a layer of
HP-55. It is hoped that these core-shell
particles will then serve as nucleation sites for further HP-55 growth in
solution, increasing encapsulation efficiency.
Once fully characterized, these composite nutraceutical particles will
be tailored for gastrointestinal tract delivery. Their smaller particle size will increase
iron bioavailability for consumers.
|
Vestal, Jacob M. |
|
|
Department(s): |
Chemical Engineering Nuclear Engineering |
|
Research |
Mohamed Bourham/Nuclear
Engineering |
|
Title of Presentation: |
Use of Magnetorheological
Fluid for Use as a Tunable Mold for Polymer Processing |
Magnetorheological Fluid (MR
Fluid) is an engineered, thermodynamically stable suspension of paramagnetic
microparticles in a carrier fluid. When
subjected to a magnetic field, the paramagnetic particles form chainlike
structures that result in a dramatic increase in viscosity. The phase immiscibility between a
glycol-based MR fluid with PDMS precursor is exploited in this study in a
system that utilizes the MR fluid in conjunction with an applied magnetic field
to change the shape of a drop of PDMS precursor containing catalyst in a new
kind of dynamic molding process. The
Process is being studied for the continuous production of six-pointed 'caltrop'
shapes, as well as uniformly hollow fibers.
Implications on the fields of antifouling, membrane-based gas
separation, and airplane wing icing are discussed.
|
Womack, Brandon S. Holmes, Thomas W. Brown, Brandon S. |
|
|
Department(s): |
Nuclear Engineering |
|
Research |
Paul J. Turinsky/Nuclear Engineering J. Michael Doster/Nuclear Engineering |
|
Title of Presentation: |
Rail Shippable Natural Circulation Boiling Water
Reactor |
This project is looking into
a new reactor design type that is based off of the current design of the General
Electric-Hitachi Economic Simplified Boiling Water Reactor (ESBWR) Nuclear
Steam Supply System (NSSS) and its containment. This entails a design based
upon using passive safety for the NSSS. The innovation of this design is that
the reactor will be in a modular style and be small enough to fit on a rail car
for shipping purposes. The package that will be included on the rail car will
consist of the reactor pressure vessel and drywell. This design concept will
mainly be constrained by the weight and length that a rail car can support. In
the design of the core, various computer codes will be used for simulations to
determine the maximum reactor power output as constrained by thermal hydraulic
limitations. To determine the core's power distribution, the Monte Carlo
N-Particle Transport Code (MCNP) will be used to simulate nuclear processes.
The output from MCNP is then coupled with Cobra-EN to complete the thermal
hydraulic analysis of the core. Iterations between the two programs will then
give an accurate power distribution and void faction of the core. To evaluate
the passive safety performance we will use a program, calculated in MathCAD,
which takes into account the flow loses throughout the NSSS, i.e. core and the
internal packages, which will give the necessary fuel and reactor vessel
heights to assure an adequate mass flow rate through the core.
|
Wormald, Jonathan L. |
|
|
Department(s): |
Nuclear Engineering |
|
Research |
Ayman Hawari/Nuclear
Engineering |
|
Title of Presentation: |
Monte Carlo Modeling and Burnup Assessment For the NCSU PULSTAR |
This project involves performing coupled
MCNP-MONTEBURNS-ORIGEN simulations of the PULSTAR reactor at NCSU. MONTEBURNS-ORIGEN simulates the
"burnup" of nuclear fuel. When
joined with the 3-D Monte Carlo capabilities of the MCNP code, accurate
simulations can be performed of nuclear reactor cores during a certain level
and length of operation of the reactor.
During operation nuclear fuel (U-235) is used up, which makes the
reactor less reactive. Reactivity is a
measure of how much a reactor differs from the critical state. The excess reactivity is a measure of the
reactivity in a reactor beyond that needed to make it critical. This project aims at producing the proper
description of reactivity history for the PULSTAR reactor model so that
simulations result in more accurate results including the prediction of fuel
needs.
|
Zmithrovitch, Katrina L. McClellan, Ryan Clearfield, Raphael |
|
|
Department(s): |
Materials Science and
Engineering |
|
Research |
Hans Conrad/Materials
Science and Engineering |
|
Title of Presentation: |
Microstructural Control of
7085-T7452 Forgings |
Seven-thousand series aluminum
alloys have, for many years, been used in the aircraft industry. Because an increased solute content in an
aluminum alloy has a strengthening effect, less material can be used for the
same stress load on a given part. This
is an extremely favorable quality in aerospace applications because the overall
weight and cost of building is reduced. Aluminum alloy 7085 is a 7000 series
alloy that is used in both the Airbus A-380 and the F-35 fighter. For added strength Mg, Cu, Zn, and Zr are
added to AA7085. The rejection rate of Alcoa’s AA7085 forgings is unacceptably
high. During solution heat treatment,
AA7085 recrystallizes when forged at a temperature below 730 F. This leads to
the rejection of the alloy by Alcoa because of unacceptably low fracture
toughness. When the forging temperature is increased to 730 F--830 F voids
form, which also causes the forging to be rejected. The current Alcoa
manufacturing practice consists of homogenizing the AA7085 billet, an initial
forging, and a final forging to the final shape of the product, a solution heat
treatment, and an aging process. A solution heat treatment and a precipitation
heat treatment will be added between the first and second forging operations
below 730 F to eliminate recrystallization in the finished AA7085 product.
[ 2009 Undergraduate Research Symposium
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