Experimental
measurement of the dispersion relation of capillary waves by laser
interferometry: Noncontact determination of the surface tension of
water-ethanol binary mixtures
Adam Perkins, Department of Physics
The current methods of determining surface tension share a common
general idea. The Wilhelmy plate, the ring, and the rod-pull
methods all employ a technique in which a foreign object is placed in
the solution being studied. In this study, we describe a novel
noninvasive method based on laser interferometry to measure the
dispersion relation of capillary waves on fluids.
Surface waves on fluids, with wavelengths less than one cm, are known
as capillary waves. In this wave regime, surface tension and viscosity
determine the propagation characteristics and attenuation of surface
waves, while gravity plays a minor role. For this reason the
dispersion and attenuation data of capillary waves may be used to
obtain the surface tension and viscosity of fluids. Our system
constitutes a new technique for generation and detection of standing
and traveling capillary waves. We are able to map the profile,
and determine the propagation speed and attenuation of these waves with
unprecedented accuracy. Here we describe the use of the system in
measuring the surface tension of binary fluids.
We present dispersion data for pure water and a number of water-ethanol
binary mixtures with various ethanol concentrations. The surface
tension is obtained by a global fit of the dispersion data using the
surface tension as an adjustable parameter. Results are compared to the
published data on surface tension of pure water and to previous studies
and methods that have determined water-ethanol surface tension.
Our results are in good agreement with the most reliable published data.
Late Quaternary
Eolian Sand Stringers on the Iowan Surface of Bremer and Black Hawk
Counties, Northeast Iowa
Jesse Koch, Geology and Geography major, and Dr. James Walters,
Department of Earth Science
The Iowan Surface of Northeast Iowa is a low relief, extensively
eroded, Pre-Illinoian till plain. Much of the surface is
blanketed with loamy sediments of eolian origin. In places, sandy
deposits are also present. Extensive deposits of eolian sand
occur on the east and southeast side of the Cedar River in Black Hawk
and Bremer Counties. County soil surveys refer to these features
as dunelike, although we choose to call them sand stringers to
emphasize their low profiles. A GIS study of soil surveys
produced several maps showing the distribution of the stringers, which
display a strong northwest-southeast orientation (~310°).
They typically rise 3-5 m above the surrounding Iowan Surface, have
widths from 20-100 m, and can be traced for up to 20 km. The
stringers are continuous across the landscape and in places they have
even blocked small drainageways and caused ponding and the formation of
very poorly drained organic soils. Particle size analyses, study
of sand surface textures, and other investigations are currently
underway in an effort to better understand the characteristics of these
sediments. The stringers appear to be very similar to features
described from the Iowan Surface of southeastern Minnesota, where
formation in a late Quaternary periglacial environment has been
suggested.
Are Larval and
Neotenic Ambystoma Tigrinum Differentially Adapted to Temperature?
Colleen K. Chisman and Dr. Jeffrey W. Tamplin, Biology Department
56 larval and 32 neotenic tiger salamanders (
Ambystoma tigrinum) were exposed to
4 treatment temperatures for 28 days. Treatment temperatures were
10
oC, 15
oC, 20
oC, and 25
oC;
14 metamorphosing larvae and 8 neotenic larvae were placed into one of
4 treatment temperatures. Salamanders were fed
Pimephales promelas daily; mass of
individual prey items were recorded and used to calculate total tissue
ingested∙day
-1∙gram
-1 for each salamander.
Growth was determined via measurement of both wet weight and length for
each individual salamander on a weekly and biweekly basis,
respectively. Survivorship and mortality data were recorded daily
and used to generate a 28 day LT
50.
All salamanders were active and fed vigorously at all treatment
temperatures. Metamorphosing larvae consumed more tissue∙day
-1∙gram
-1
compared to neotenic larvae. Metamorphosing larvae from Iowa were
more sensitive to higher temperature regimes (20
oC and 25
oC)
as evidenced their low LT
50 values and higher mortality rates
compared to neotenic larvae from Mexico. Among the Iowa larvae,
100% mortality occurred at 25
oC, and 92.8% of individuals
died at 20
oC. In contrast, 50% of neotenes from Mexico
survived at 25
oC, and 62.5% of individuals died at 20
oC
for 28 days.
Design and
Development of Starr Hydro-Wind Power Station
Dennis Craun, Manufacturing Technology Major, Rusty Elson, EIET Major,
Tony Kanne, Manufacturing Technology Major, Billie Johnson,
Manufacturing Technology Major, John Mackamul, EIET Major, Brian
Mayfield, EIET Major, Easie Toingar, EIET Major, Department of
Industrial Technology.
Advisors: Dr. R. Pecen and Dr. M. Fahmy, Department of Industrial
Technology
The team has established a partnership with the Black Hawk County
Conservation Board, the conservation board has agreed to allow the
installation of a permanent structure to utilize renewable green energy
at Hickory Hills Park. UNI students will be able to monitor
different configurations and record the data enabling students and
researchers to evaluate the efficiency of the system. While
research is taking place the Black Hawk County Conservation Board will
be able to use the power generated, the system could potentially save
them 20% on their electric bill for Hickory Hills Park. Both UNI
and the Black Hawk County Conservation Board intend to expand the
hybrid system by adding solar panels, geothermal and other technology
to increase the reliability of the system. Conducting this
research at the Hickory Hills site will allow data to be collected in
an environment that provides real time data with real instead of
assumed variables. This research also works well with the goals
of the Black Hawk County Conservation Board. Another aspect of
the system is to design the system so that educational events can be
held with participants being allowed to see the system in operation by
using clear polycarbonate safety shields so that participants can view
the system in operation. Also to demonstrate to Iowans that
renewable resources are available locally and can be used in a
practical manner. The structure of the system was designed to
enable future changes with minor modifications. The Black Hawk
County Conservation Board would like to see Hickory Hills Park
self-sufficient for its electrical needs and the future.
Although the initial design does not have an extensive amount of
research to enable the most efficient design, the supporting
infrastructure will be in place. This includes a base for a
thirty foot tower; a six inch pipe with at least twenty feet of head
for a source of hydro power, and a service building made using
Insulated Concrete Forms to last for many years and provide good
insulation. All of the pipe will be below the frost line to allow
year round operation. And the wind turbine will have a vertical
axis; this should reduce the amount damage from ice throws that have
occurred on some horizontal axis wind turbines. Future students
and researchers can use the data obtained from the monitoring devices
to evaluate the systems and their components. From this
information necessary changes can be made and observed.
Design and
Development of a Solar Electric Boat to Promote Zero Emission
Dan Frisch, EIET Major, Eric Schumacher, EIET Major, Matt
Brustkern, EIET Major, Jamie Ruth, Manufacturing Tech Major, Jack
Steuben, Manufacturing Tech Major, Phillip Tentinger,
Manufacturing Tech Major
Advisors: Dr. R. Pecen and Dr. M. Fahmy, Department of
Industrial Technology
Boat Technologies for Iowa Lakes and Rivers.
This is a project students and faculty have been working for two
years now as a part of grant provided by Iowa Energy
Center. This year’s design include individual solar cells connected by
students rather than using commercially available solar panels, a much
better drive train, enhanced electrical system with electronic
controls, and improved stirring system.
Gas Phase
Formation Of Cyclohexene From Pyranose.
Timothy M. Schramm and Curtiss Hanson, Department of Chemistry
As ethanol becomes a more popular alternative energy source, a more
efficient and cost effective process to create it is desired. The
depolymerization of biomass starch into monosaccarides to ferment using
organisms is a widely used method. The depolymerization process
is done by pyrolysis, or heating in the absence of oxygen. The
pyrolysis process creates phenolic toxins as well as the
monosaccarides. The reaction process that takes place to create
these toxins is unknown. Experiments executed to discover the
reaction process were done using a Fourier transform ion cyclotron
resonance (FT-ICR) mass spectrometer. The instrument’s ability to
contain and detect ions and their reaction products over a period of
time is fundamental to modeling gas phase ion reactions. The
mechanism for the creation of these toxins would prove valuable to
inhibit the reaction from occurring, thus, creating a procedure to
optimize the amount of fuel
Determination of
Oxidation-Reduction Potentials of DDT Metabolites: A Computational Approach
Corey J. Stotts, Dr. John A. Bumpus, (Dept. of Chemistry, UNI)
and Dr. Christopher J. Cramer (Dept. of Chemistry and Minnesota
Supercomputing Institute, Univ. of Minnesota)
The thermodynamic properties of DDT metabolites were studied via
computational methods. The oxidation-reduction potentials of DDD
(1,1-dichloro-2,2-bis(4'-chlorophenyl)ethane) and DDMS
(1-chloro-2,2-bis(4'-chlorophenyl)ethane) were calculated, as was the
pKa of dicofol (1,1-bis(4'-chlorophenyl)-2,2,2-trichloroethanol).
Geometries and frequencies were obtained at the B3LYP/6-31G(d) level of
theory, energies at the B3LYP/6-311+G(d) level and standard-state
aqueous free energies at the BPW91/6-31G(d) level using the SM5.42R
solvation model. The one and two electron oxidation-reduction
potentials of DDD were calculated as -0.24 V and 0.071 V respectively.
The corresponding values for DDMS were calculated as -0.61 V and -0.025
V. These values agree with observed accumulations in the environment.
The pKa of dicofol was calculated as 8.6, in agreement with
experimental evidence.
Theoretical
Neuroscience: Modeling the Activation Mechanism of Potassium
Channels in Neurons"
Kevin Twedt and Dr. C. C. Chancey, Department of Physics
We have modeled the electrostatic interaction between the S4 segment of
the potassium channel molecule and the surrounding water molecules on
both the intracellular and extracellular sides of the neural axon cell
membrane. Two methods were used to approximate this interaction: (i)
a macroscopic evaluation in which the water was treated as a dielectric
medium with dielectric constant 80; (ii) a microscopic evaluation
considering the effects of each individual water molecule fixed in
position within the water pockets surrounding the S4 segment. The
potential energy of the S4 due to the water pockets was plotted against
the rotation of the S4 segment, while keeping the water pockets in
their fixed positions. Although the two methods gave some differing
results, both methods produced single well potential energy curves of
~6-9 eV depth. Based on this energy curve, we show that other forces
on the S4 must create an effective torsional spring force with spring
constant k~3-5 eV in order to produce a two well potential energy curve
in qualitative agreement with experimental data.
Physics of
Potassium Ion Channel Inactivation in Neurons
Ryan M. W. Collins and Dr. C. C. Chancey, Department of Physics
The electrical signaling capabilities of neurons depend on the flows of
ions into and out of their axons. Potassium ions exit an axon’s
interior through a potassium channel or pore that connects the
intracellular region with the extracellular region. The channel opens,
or is activated, allowing potassium ions to exit. The channel then
undergoes a blocking transition in which the channel is physically open
but is blocked by some part of the larger channel molecular. This
blocking process is called inactivation, and the physics by which it
might occur forms the topic of our investigation. The N-terminus
region of the Drosophila shaker potassium ion channel was identified by
Hoshi et al as having an important role in channel inactivation. Using
the last 19 amino acids in the N-terminus region, a mass and net charge
were calculated. We investigated two forces that might affect the
motion of this N-terminus mass (tentatively identified as the blocking
or inactivation particle): the magnetic field effects due to potassium
ion current in the channel, and an electric force due to the decreasing
density of potassium ions from the intracellular region.
Time-of-flight calculations were calculated for the inactivation
particle. These times will be discussed in terms of typical
inactivation processes.
Factors Affecting
Student Achievement in College Physics
Jason Djuren & Dr. Andrea Pascarella, Department of Physics
Numerous factors can influence students’ learning
in college classes. This study examines some of the factors that can
affect students’ performance on a conceptual evaluation given pre- and
post- instruction in an introductory algebra-based physics course. In addition to the conceptual evaluation,
survey data was gathered to obtain information about students’
backgrounds, epistemological beliefs, and attitudes towards class.
Students also provided feedback about the impact course elements such
as lecture, problem solving, and hands-on activities had on their
learning. This data was then related to students’ achievement on the
conceptual exam and statistically significant differences between high
and low achievers were examined. The interpretation of these results
will be discussed at our poster presentation.
The Role of Dominance
in Stereotype Threat Effects
Michael Philipp and Dr. Helen Harton, Department of Psychology
Stereotype threats are triggered when one's membership in a particular
group is linked to a negative performance on a task. Individuals
exposed to stereotype threats (e.g., women are told that men perform
better on a given math test) who identify themselves as being members
of the underachieving group perform more poorly than members of the
same group for whom the stereotype was never mentioned. Although a few
basic social psychological factors have been demonstrated to mediate
the effects of stereotype threat (e.g., the individual's group
identification, domain identification, stereotype awareness), little
research has examined the effects of more biologically influenced
factors (i.e., social dominance and testosterone).
This research begins to examine the effects of testosterone on
stereotype phenomena by illustrating some of the potential mechanisms
that may handicap high testosterone (High-T) individuals. Previous
findings hypothesize that High-T individuals are more susceptible to
the effects of stereotype threat because the negative stereotype is
perceived by the High-T individual as a potential threat to social
status within the given domain. Thus, rumination on the potential
threat to status reduces the cognitive resources available to process
the task at hand and, thus, their performance suffers. This explanation
is supported by the trends emerging from the present study.
In this study, participants were invited to participate in math
assessment validation study. Before the study began, each participant
completed a social dominance scale (as an indicator of testosterone
levels). Then each group was either given no reminder of a stereotype
or reminded of the popular stereotype that "females tend to do worse on
tests of mathematics than men." After the stereotype manipulation,
participants completed a pre-task survey of math identification, a math
performance task, and finally a post-task survey of math
identification.
Findings indicate (as predicted) that among more dominant (i.e.,
Higher-T) female participants, those reminded of the stereotype
performed worse on the math performance task than those who were not
exposed to the stereotype. Additionally, highly dominant females rated
themselves as more highly identified with the math domain when exposed
to the stereotype than when not reminded of the stereotype at all. This
bolstering of math identification is evident even after the task,
suggesting that the threat has effectively elicited many
status-protective thoughts. The effort put forth in generating these
status-protective thoughts may reduce the cognitive resources available
to the individual and be ultimately responsible for the overall
underperformance on the math task.
Photodegration of
malachite green by titanium dioxide in different conditions
Alexander B. Nepomnyashchii, Dr. Shoshanna R.Coon, & Dr. John.A
Bumpus; Department of Chemistry
Degradation of malalchite green is an effective process that results in
complete degradation of compound and formation of ammonia, carbon
dioxide and water. As a catalyst for photodegradation was used
industrial Degussa P25 titanium dioxide. This catalyst is found to be
in anatase form. MG is a colored solution, due two the conjugated
system of three rings, that shows absorption at 615 nm. Influence of
concentration of MG, mass of titanium dioxide and pH of the solution
has been studied. Increasing of mass of titanium dioxide promote the
photodegradation in the range of 450-900 mg/l. More acidic solutions
show the higher rate of photodegradation as basic solutions inhibit
photodegradation. Increasing of dye concentrations inhibits
photodegradation and at concentrations close to 150 ppm practically
there is practically no degradation at all.
