Tag Archives: Physical Sciences

Osseointegration on a Carbon-Infiltrated Carbon Nanotube Coated Titanium Surface

Jacquelyn Monroe, Brian Jensen, Laura Bridgewater, Natalie Kwon, Brigham Young University

Osseointegration plays a vital role in orthopedic surgery, as bone cells should be able to adhere and form on the implant surface to enable strong mechanical connection. Titanium has long been used in orthopedic and prosthetic implants because of its known toughness, strength and low conductivity, and especially its biocompatibility. However, native bone growth onto titanium is not optimal. Previous work in our lab has developed a carbon-infiltrated carbon nanotube surface which exhibits structural antimicrobial properties. The purpose of the present work was to evaluate osteoblast growth on this surface to determine whether the coating was cytotoxic, neutral, or osteogenic. Vertically aligned carbon nanotubes were grown on top of commercially pure titanium samples using ethylene and hydrogen gas at 750C, followed by infiltration at 900C. Our control sample was an uncoated commercially pure titanium sample. Both the control and CI-CNT coated titanium samples were cell cultured with human osteoblasts kept at 39C for approximately 96 hours. The preliminary tests have shown that the CI-CNT coated titanium sample promotes enhanced osteoblast proliferation, as well as functionalization (e.g., they are laying down calcium as part of bone formation). These results may lead to an orthopedic implant coating which provides both structural antimicrobial behavior, as well as enhanced osseointegration.

MultiCRAFTI: Overcoming the Kinetic Energy Limitation to Measure the Cross Section of High-Mass Ions

Brigham Pope, Daniel Joaquin, Jacob Hickey, Brigham Young University

CRAFTI is an emerging method for measuring molecular collision cross sections using the ultra-high resolving FTICR-MS instrument. Collision cross sections are important measurements to understanding size, tertiary structure, and ligand binding. CRAFTI has been shown to give accurate collision cross sections comparable to those from drift ion mobility, the leading cross section measurement method. Because CRAFTI measurements are carried out under single-collision conditions, CRAFTI can obtain cross sections for non-covalently bound complexes with interactions that are far too weak to address using drift ion mobility, where multiple thermal collisions can disrupt the complexes. However, CRAFTI‰Ûªs requirement of single-collision ion dephasing is a hindrance to the measurement of larger mass ions because for ions that are massive compared to the neutral collision partner it is difficult to reach sufficient center-of-mass kinetic energy to cause dephasing (which usually occurs via collision-induced dissociation). In this study, we characterize these limitations by measuring different species (tetraalkylammonium, cryptand-metal ion, and cucurbituril complexes) at a range of kinetic energies. For polyatomic ions, CRAFTI cross sections are observed to increase with increasing center-of-mass kinetic energy until they reach a limiting value that is generally similar to cross sections computed from the expected molecular structure. The CRAFTI measurement reaches the calculated cross-section at a specific center-of-mass kinetic energy related to the energy of the bond being broken. We also performed MultiCRAFTI, a new experiment where we overcome the kinetic energy limit through simultaneous measurements of multiple species for internal comparison. Two analytes in a MultiCRAFTI experiment, though both are beneath the minimum kinetic energy requirement, give correct relative cross sections. These MultiCRAFTI measurements represent a new step toward extending the FTICR-MS to vital new areas of measurement in macromolecules and organo-metal complexes.

Resistivity of Nickel Thin Films

Michael Maynard, Alex Mitchell, Dixie State University

As metal films get thinner, their resistivity increases. We study the phenomenon using nickel films. The nickel films are made in a vacuum system with pressures below 10^-7 Torr. A nickel filament is heated to 1200å¡C to sublimate the nickel onto our glass substrate. A four-point measuring probe was used to measure voltage drops across the film at known currents. This gave a sheet resistance. Thicknesses of the thin films was verified by images on a scanning electron microscope. Thicknesses varied from 40nm-255nm. Resistivity of films were calculated to be between 22-147ë©nm. A graph of resistivity vs thickness will be presented and discussed on this poster.

Sources and Composition of Atmospheric Particulate Matter in the Salt Lake Valley

Andrew Piskadlo, Adele Reynolds, Anna Robert, Gaurav Pandey, Westminster College

Air pollutants pose a significant health risk in urban environments. Particulate matter 2.5 microns or smaller (PM 2.5) is of special concern because it can penetrate deep into lungs. Salt Lake City (SLC) is well-known for its winter inversions with PM 2.5 levels frequently exceeding EPA standards, but air pollution during the summer months is of growing concern. While dust storms are known to occur each year in SLC, the predominant source of the atmospheric particles, their origin, chemical composition, and particle size distribution have yet to be identified due to lack of research. Newly exposed lake sediments are highly prone to dust generation. The recent drought in 2011-2016 caused a 30% decrease in the volume of the Great Salt Lake (GSL), and water levels in the GSL fell dramatically to record lows in 2016, exposing large tracts of dry lake bed. It is unclear to what extent these exposed GSL sediments produce dust, and if that dust affects air quality in the Salt Lake valley or represents an important source of atmospherically transported metals to downwind aquatic environments. Our study was designed to answer these research questions. Samples of total particulate matter and PM 2.5 were collected with atmospheric samplers at Westminster College and several other sites. Samples were then digested and analyzed for their trace element and heavy metal content by ICP-MS. Though this study is ongoing, preliminary results suggest a possible increase in particulate matter as the summer progresses, potentially associated with periods with elevated atmospheric particulate matter in the Salt Lake Valley, in part derived from wildfires in the wider region.

A fossil-pollen-based climate reconstruction of two lake records from the Uinta mountain range in northern Utah.

Andrew Kennedy, University of Utah

Climate change is an issue that has gained a significant amount of attention in recent years. Specifically, anthropogenic climate change, as we know the Earth’s climate goes through cycles of warming and cooling. In recent years, there have been examples climate changing rapidly and creating problems for communities around the world. The goal of this study is to look at patterns of climate change through reconstructing a climate history by analyzing two frozen lake sediment cores northern Utah. The two study sites are from both Newt Lake outside of Vernal Utah and Canyon Lake located outside of Duchesne Utah. In this study we have counted the charcoal from the sediment cores, and we have analyzed the pollen grains in the core. As we count the charcoal from the frozen lake sediment core we are able to determine the study site’s fire interval and look at charcoal peaks this can help establish a general idea of how often fires come through the two study sites. Once we gather this data we can examine it to determine if there has been any changes in the fire interval in recent years. Additionally, as we prep and analyze the pollen data in the sediment core we can look at the individual species of pollen to determine the climate envelope of each species to get some idea of what the climate would have looked like at a given time. This study will provide the reader with information about how climate has been changing in Utah and give insight as to what the study sites may have looked like at a given time compared to today.

Uncertainty in Optical Particulate Counting Sensors

Jared Blanchard, Brigham Young University

In order to mitigate the health problems and environmental damage caused by the burning of biomass in homes across the developing world, there is an international effort to design clean burning cookstoves with greater efficiency and fewer harmful emissions. An important measuring tool for gauging the effectiveness of these alternate stoves is the optical particulate counter. This type of sensor beams light through the contaminated air and measure how much of that light is refracted. Based on these measurements, the size and amount of particles in the air can be inferred. However, for the most part, these measurements are taken at face value, without an understanding of the amount of uncertainty involved in the measurement process. This project describes the development of an accurate mathematical model for a particular sensor, the OPC-N2 by Alphasense, and states how this model leads to increased understanding of the uncertainty involved in the operation of our sensor and therefore, sensors like it.

Jet Impingement on Superhydrophobic Surfaces: Effect of Post Microstructure on Heat Transfer

Dewey Potts, Brigham Young University

Liquid jet impingement is an excellent solution for many thermal management challenges (e.g. cooling of advanced microelectronic devices) because of its high heat transfer rates. Superhydrophobic surfaces, with micrometer scale posts, have desirable self-cleaning and anti-fouling properties and their use has been proposed in these applications; however, superhydrophobic surfaces also decrease heat transfer rates. The relationship between superhydrophobic surface post microstructure and heat transfer rate in liquid impinging jets has not yet been explored. To better understand this relationship, experiments are conducted with varying pitch, the distance between posts, and varying cavity fraction, the area not covered by the posts divided by the total area. This empirical data is then utilized to develop models, which will predict heat transfer based on pitch and cavity fraction. Designers of thermal management systems may then install post patterned superhydrophobic surfaces in thermal management devices to utilize their desirable properties and may maximize heat transfer rates by selecting the optimal pitch and cavity fraction.

Public Understanding, Opinions, and Questions about Hot Topics in Science

Alexandria DeGrauw, University of Utah

Past research has shown that, though the U.S. public generally views science favorably, the benefit of scientific inquiry has decreased in value. According to the PEW Research Center (2015), only 79% of people thought science was generally positive and made life easier for most people. This paper seeks to explore why people may view science negatively by gauging participants‰Ûª responses to genetically modified organisms, a controversial topic in science. Participants were gathered from upper division writing courses at the University of Utah, and they were asked to complete a science knowledge quiz, several questionnaires, an interview, and a think aloud protocol. Their responses were analyzed to determine their science knowledge and what questions they had about GMOs and science. Preliminary findings show most questions were geared towards the methods behind GMOs. References: Funk, C.,Rainie, L., and Page, D. (2015). Public and scientists‰Ûª views on science and society. Pew Research Center. Retrieved from http://assets.pewresearch.org/wp-content/uploads/sites/14/2015/01/PI_ScienceandSociety_Report_012915.pdf

Grain Boundaries and Diffusivity

Katie Varela, Brigham Young University

Diffusion of atoms through materials is important for a number of material processes, such as air purification, fuel cells, and material behavior. The interfaces between crystals, also known as grain boundaries, are considered to be rapid diffusion pathways through a material. To better understand how these grain boundaries affect diffusion in a material, we simulate diffusion in a variety of atomic structures. The goal is to correlate the diffusivity with other properties of the grain boundaries, such as their energy.