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---
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title: Academic Achievements
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imageUrl: /img/library.jpg
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blurImageUrl: /img/library_blur.jpg
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motto: Academic Publications and Presentations
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---
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<!-- Thesis -->
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<dl>
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<dt>Polyoxometalate Incorporation and Effects on Proton Transport in
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Hydrogel Polymers</dt>
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<dd>
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A Thesis Presented for the Degree of Master of Science of Chemical
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Engineering in the University of Idaho by Thomas Allen Christensen II
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<br />
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Major Professor: James G. Moberly, Ph.D.
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<br />
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Committee Members: Kristopher Waynant, Ph.D.; Mark Roll, Ph.D.
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<br />
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August 2020
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<br />
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<a data-toggle="collapse" data-target="#thesis-abstract" role="button">Abstract <span class="caret"></span></a>
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<a href="#"><i class="fas fa-file-alt"></i> Full Text (pending)</a>
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<div class="collapse" id="thesis-abstract">
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<p class="font-serif">
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Polyoxometalate clusters embedded into hydrogel biobeads may be able to solve
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the challenges posed by free proton generation during remediation of
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trichloroethylene by acting as buffers and reducing protons to hydrogen gas. In
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this thesis, the challenges posed by systems that contain both diffusion and
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reaction processes for protons are considered mathematically, and a computer
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simulation to was developed to prove the relationship between diaphragm cell lag
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period and reactive capabilities of membranes. Two polyoxometalate compounds,
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sodium decavanadate and alumina sulfate, were successfully incorporated into a
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poly(vinyl alcohol) hydrogel membrane, and the diffusivity changes associated
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with each compound was determined. It was found that the diffusivity of protons
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through an unmodified 10% w/v poly(vinyl alcohol) membrane was 1.76 ×
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10<sup>-5</sup> cm<sup>2</sup> s<sup>-1</sup>, the diffusivity through a 10%/2%
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w/w/v poly(vinyl alcohol)/sodium decavanadate membrane was 3.10 × 10<sup>-6</sup>
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cm<sup>2</sup> s<sup>-1</sup>, and the diffusivity through a 10%/2% w/w/v
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poly(vinyl alcohol)/alumina sulfate membrane was 3.32 × 10<sup>-7</sup>
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cm<sup>2</sup> s<sup>-1</sup>. Through analysis of the diaphragm cell lag
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period, it was found the incorporation of sodium decavanadate did not increase
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the reactivity of a poly(vinyl alcohol) hydrogel, and incorporation of alumina
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sulfate lowered the reactivity. These results indicate that polyoxometalate
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integration into hydrogel membranes is feasible, but does not provide any
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advantage to a bioremediation scenario.
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</p>
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</div>
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</dd>
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</dl>
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<hr />
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<!-- Rumen metagenomics -->
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<dl>
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<dt>Metagenomic analysis of rumen populations in week-old calves as
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altered by maternal late gestational nutrition and mode of delivery</dt>
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<dd>
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T. A. Christensen II, K.J. Austin, K. M. Cammack, and H. C. Cunningham-Hollinger
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Westion Section American Society of Animal Science Annual Meeting ● Boise, ID ● June 12, 2019
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<br />
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1<sup>st</sup> Place Undergraduate Poster Competition
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<a data-toggle="collapse" data-target="#metagenomics-abstract" role="button">Abstract <span
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class="caret"></span></a>
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<div class="collapse" id="metagenomics-abstract">
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<p class="font-serif">Early colonization of the rumen microbiome is critical to host health and long term
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performance. Factors that influence early colonization include maternal factors such as gestational
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nutrition and mode of delivery. Therefore, we hypothesized that late gestational nutrition and mode of
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delivery would influence the calf rumen microbiome. Our objectives were to determine if nutrient
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restriction during late gestation alters the calf rumen microbiome and determine if ruminal microbiome
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composition differs in calves born vaginally versus caesarean. Late gestating Angus cows were randomly
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allocated to one of three treatment groups: control (<b>CON</b>; n = 6), caesarean section (<b>CS</b>; n
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= 4), and nutrient restricted (<b>NR</b>; n = 5), where CON were fed DDGS and hay to meet NRC
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requirements and calved naturally; CS were fed similarly to CON and calves were born via caesarean
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section; and NR were fed at a level to reduce BCS by 1.5-2.0 points over the last trimester compared to
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CON and calved naturally. Rumen fluid was collected via oral lavage prior to partition from cows and at
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d 7 from calves. Microbial DNA was isolated from the rumen fluid and metagenomic shotgun sequencing was
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performed using the Illumina HiSeq 2500 platform. Sequence data were analyzed using Metaxa2 for
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taxonomic assignment followed by QIIME1 and QIIME2 to determine differential abundance and alpha- and
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beta-diversity differences. There were no significant differences in alpha-diversity as measured by
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shannon index across treatment groups for cows (<em>P</em> = 0.239), but there were significant
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differences for calves (<em>P</em> = 0.015). Similarly, there were no significant differences in
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beta-diversity as measured by the bray-curtis dissimilarity matrix for cows (<em>P</em> = 0.059), but
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there were significant differences for calves (<em>P</em> = 0.007). Alpha-diversity differed (<em>P</em>
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< 0.001) between cows and calves, with cows having increased species richness compared to calves.
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Beta-diversity also differed (<em>P</em> = 0.001) between cows and calves. At total of 410 taxa were
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differentially abundant (<em>P</em>
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< 0.01) between cows and calves. These results suggest that the mature rumen microbiome of cows is
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able to withstand changes in feed intake, however the calf microbiome is susceptible to
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alteration by maternal factors. These data also suggest that there may be opportunities to
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develop management strategies during late gestation that influence calf health and performance
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long-term.</p>
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<p><b>Key words</b>: gestation, metagenomics, microbiome, rumen</p>
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</div>
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</dd>
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<hr />
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<!-- ChemE Car -->
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<dt>The ChemE Car that Cud: Entry and Documentation Packet to AIChE ChemE Car Contest</dt>
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<dd>
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Thomas Christensen II, Andrew Halverson, Kennedee True, Seth Messick, Amanda Christensen, Caleb Richmond,
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Alexander Brown, & Jake Maksin with Dr. David Bagley
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Rocky Mountain Regional AIChE Student Conference ● Golden, CO ● April 6, 2019
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<br />
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2<sup>nd</sup> Place Poster Competition ● 7<sup>th</sup> Place Performance Competition
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<a data-toggle="collapse" data-target="#cheme-car" role="button">Abstract <span class="caret"></span></a>
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<a href="https://hdl.handle.net/20.500.11919/3817"><i class="fas fa-file-alt"></i> Full Text</a>
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<div class="collapse" id="cheme-car">
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<p class="font-serif">The ChemE Car That Cud showcases Wyoming’s dominant industries of agriculture and
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mining by utilizing rumen fluid from a cannulated beef cow to generate hydrogen to be used in a hydrogen
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fuel cell and radioactive cesium, a byproduct of uranium that is often obtained from Wyoming’s mines, to
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time the car’s stop. The concentration of cesium-137 source is measured using the radioactive decay of
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cesium shielded by aluminum. The painted aluminum chassis was obtained from a previous team at UW, and
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modified using plastic k’nex toys to adapt to the current power source and stopping mechanism.</p>
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</div>
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</dd>
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<hr />
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<!-- AIChE Poster -->
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<dt>Measuring Diffusion of Trichlorethylene Breakdown Products in Polyvinylalginate</dt>
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<dd>
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Thomas A. Christensen II, Samuel R. Wolfe, Jonathan Counts, Mark F. Roll, Kristopher V. Waynant, James G.
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Moberly
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AIChE Annual Meeting ● Pittsburgh, PA ● October 29, 2018
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3<sup>rd</sup> Place Environmental III Division Undergraduate Poster Competition
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<a data-toggle="collapse" data-target="#pva-aiche" role="button">Abstract <span class="caret"></span></a>
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<a href="https://aiche.confex.com/aiche/2018/meetingapp.cgi/Paper/545790"><i class="fas fa-calendar-alt"></i> Conference Schedule</a>
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<div class="collapse" id="pva-aiche">
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<p class="font-serif">Trichloroethylene (TCE), a toxic and carcinogenic contaminant, presents unique
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challenges for cleanup because of its water solubility, density, and volatility. Bioremediation of TCE
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is a promising cleanup method; however, metabolism of TCE results in acid generation that inhibits
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remediating microorganisms. Calcium alginate(CA)-polyvinylalcohol (PVA) hydrogels show promise for
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protecting remediating microbes, however diffusion of TCE or its byproducts through these polymers is
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unknown. To measure the effective diffusion coefficient of TCE and byproducts through hydrogel
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membranes, we used a modified diaphragm cell. Measured effective diffusion coefficient of each species
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was (cm<sup>2</sup>/s ×10<sup>6</sup>): 14.0 ± 1.91 for H+ ions, 12.4 ± 1.64 for TCE, 7.83 ± 0.54 for
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cis-1,2-dichloroethylene (DCE), and 4.68 ± 4.14 for vinyl chloride. These results aid in engineering
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biobeads and suggest that CA-PVA hydrogel blends are effective in slowing diffusion of protons,
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buffering acids produced by trichloroethylene metabolism, and remains suitable for encapsulation of
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microorganisms involved in bioremediation.</p>
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</div>
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</dd>
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<hr />
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<!-- Fast Pitch speech -->
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<dt>How to build a cow-cud fuel cell</dt>
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<dd>
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Thomas A. Christensen II
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<br />
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Idaho INBRE Summer Research Conference ● Moscow, ID ● August 1, 2018
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<br />
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3<sup>rd</sup> Place Fast-Pitch Science Presentation Contest
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<br />
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<a href="https://web.archive.org/web/20190928024416/https://inbre.uidaho.edu/research/research-conference/"><i class="fas fa-trophy"></i> Awards
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Listing</a>
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</dd>
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<hr />
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<!-- INBRE Poster -->
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<dt>Measuring diffusion of protons in polyvinylalginate</dt>
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<dd>
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Thomas A. Christensen II, Jonathan Counts, James G. Moberly
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<br />
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Idaho INBRE Summer Research Conference ● Moscow, ID ● July 31, 2018
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<br />
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Undergraduate Poster Competition
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<br />
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<a data-toggle="collapse" data-target="#pva-inbre" role="button">Abstract <span class="caret"></span></a>
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<a
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href="https://eventmobi.com/idahoinbre2018/people/c861bd6f-f4a7-4d67-a59a-199e34515776/387725dc-c893-44b6-b611-0abdf5fbcf6e"><i class="fas fa-calendar-alt"></i> Conference
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Schedule</a>
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<div class="collapse" id="pva-inbre">
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<p class="font-serif">Trichloroethylene (TCE) is a toxic and carcinogenic contaminant that presents unique
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challenges for cleanup because of its density and volatility. Use of microorganisms may be a promising
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remediation method, however metabolism of TCE results in acid buildup, which consequently impedes the
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ability of microorganisms to perform this remediation. Polyvinylalginate (PVA) shows promise as a useful
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shield for microorganisms carrying out bioremediation of TCE by surrounding them in a protective
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biofilm-like layer, however, key information is missing which relates diffusion of TCE or its metabolic
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products through PVA. To measure the effective diffusion coefficient of H+ ions through a PVA membrane
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cross-linked with boric acid and calcium ions, we used a modified diaphragm cell. We found the effective
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diffusion coefficient to be 1.40 × 10<sup>-5</sup> ± 1.91 × 10<sup>-6</sup> cm<sup>2</sup>/s, a nearly
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seven-fold decrease in diffusivity compared to protons in water, with an unexpected significant but as
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of yet unquantified adsorption capacity. These results suggest that polyvinylalginate is effective in
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slowing diffusion of protons and buffering these acids produced by trichloroethylene metabolism, and
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remains suitable for encapsulation of microorganisms involved in bioremediation.</p>
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</div>
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</dd>
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</dl> |