pages/Academia.html

---
title: Academic Achievements
imageUrl: /img/library.jpg
blurImageUrl: /img/library_blur.jpg
motto: Academic Publications and Presentations
---

<dl>
    <dt>Polyoxometalate Incorporation and Effects on Proton Transport in
        Hydrogel Polymers</dt>
    <dd>
        A Thesis Presented for the Degree of Master of Science of Chemical
        Engineering in the University of Idaho by Thomas Allen Christensen II
        <br />
        Major Professor: James G. Moberly, Ph.D.
        <br />
        Committee Members: Kristopher Waynant, Ph.D.; Mark Roll, Ph.D.
        <br />
        August 2020
        <br />
        <a href="#">Proquest Thesis Link (pending)</a>
        &emsp;
        <a data-toggle="collapse" data-target="#thesis-abstract" role="button">Abstract <span class="caret"></span></a>
        <div class="collapse" id="thesis-abstract">
            <p class="font-serif">
                Polyoxometalate clusters embedded into hydrogel biobeads may be able to solve
                the challenges posed by free proton generation during remediation of
                trichloroethylene by acting as buffers and reducing protons to hydrogen gas. In
                this thesis, the challenges posed by systems that contain both diffusion and
                reaction processes for protons are considered mathematically, and a computer
                simulation to was developed to prove the relationship between diaphragm cell lag
                period and reactive capabilities of membranes. Two polyoxometalate compounds,
                sodium decavanadate and alumina sulfate, were successfully incorporated into a
                poly(vinyl alcohol) hydrogel membrane, and the diffusivity changes associated
                with each compound was determined. It was found that the diffusivity of protons
                through an unmodified 10% w/v poly(vinyl alcohol) membrane was 1.76 &times;
                10<sup>-5</sup> cm<sup>2</sup> s<sup>-1</sup>, the diffusivity through a 10%/2%
                w/w/v poly(vinyl alcohol)/sodium decavanadate membrane was 3.10 &times; 10<sup>-6</sup>
                cm<sup>2</sup> s<sup>-1</sup>, and the diffusivity through a 10%/2% w/w/v
                poly(vinyl alcohol)/alumina sulfate membrane was 3.32 &times; 10<sup>-7</sup>
                cm<sup>2</sup> s<sup>-1</sup>. Through analysis of the diaphragm cell lag
                period, it was found the incorporation of sodium decavanadate did not increase
                the reactivity of a poly(vinyl alcohol) hydrogel, and incorporation of alumina
                sulfate lowered the reactivity. These results indicate that polyoxometalate
                integration into hydrogel membranes is feasible, but does not provide any
                advantage to a bioremediation scenario.
            </p>
        </div>
    </dd>
</dl>

<hr />

<dl>
    <dt>Metagenomic analysis of rumen populations in week-old calves as
        altered by maternal late gestational nutrition and mode of delivery</dt>
    <dd>
        T. A. Christensen II, K.J. Austin, K. M. Cammack, and H. C. Cunningham-Hollinger
        <br />
        Westion Section American Society of Animal Science Annual Meeting &#9679; Boise, ID &#9679; June 12, 2019
        <br />
        1<sup>st</sup> Place Undergraduate Poster Competition
        <br />
        <a data-toggle="collapse" data-target="#metagenomics-abstract" role="button">Abstract <span
                class="caret"></span></a>
        <div class="collapse" id="metagenomics-abstract">
            <p class="font-serif">Early colonization of the rumen microbiome is critical to host health and long term
                performance. Factors that influence early colonization include maternal factors such as gestational
                nutrition and mode of delivery. Therefore, we hypothesized that late gestational nutrition and mode of
                delivery would influence the calf rumen microbiome. Our objectives were to determine if nutrient
                restriction during late gestation alters the calf rumen microbiome and determine if ruminal microbiome
                composition differs in calves born vaginally versus caesarean. Late gestating Angus cows were randomly
                allocated to one of three treatment groups: control (<b>CON</b>; n = 6), caesarean section (<b>CS</b>; n
                = 4), and nutrient restricted (<b>NR</b>; n = 5), where CON were fed DDGS and hay to meet NRC
                requirements and calved naturally; CS were fed similarly to CON and calves were born via caesarean
                section; and NR were fed at a level to reduce BCS by 1.5-2.0 points over the last trimester compared to
                CON and calved naturally. Rumen fluid was collected via oral lavage prior to partition from cows and at
                d 7 from calves. Microbial DNA was isolated from the rumen fluid and metagenomic shotgun sequencing was
                performed using the Illumina HiSeq 2500 platform. Sequence data were analyzed using Metaxa2 for
                taxonomic assignment followed by QIIME1 and QIIME2 to determine differential abundance and alpha- and
                beta-diversity differences. There were no significant differences in alpha-diversity as measured by
                shannon index across treatment groups for cows (<em>P</em> = 0.239), but there were significant
                differences for calves (<em>P</em> = 0.015). Similarly, there were no significant differences in
                beta-diversity as measured by the bray-curtis dissimilarity matrix for cows (<em>P</em> = 0.059), but
                there were significant differences for calves (<em>P</em> = 0.007). Alpha-diversity differed (<em>P</em>
                < 0.001) between cows and calves, with cows having increased species richness compared to calves.
                    Beta-diversity also differed (<em>P</em> = 0.001) between cows and calves. At total of 410 taxa were
                    differentially abundant (<em>P</em>
                    < 0.01) between cows and calves. These results suggest that the mature rumen microbiome of cows is
                        able to withstand changes in feed intake, however the calf microbiome is susceptible to
                        alteration by maternal factors. These data also suggest that there may be opportunities to
                        develop management strategies during late gestation that influence calf health and performance
                        long-term.</p>
                        <p><b>Key words</b>: gestation, metagenomics, microbiome, rumen</p>
        </div>
    </dd>

    <hr />

    <dt>The ChemE Car that Cud: Entry and Documentation Packet to AIChE ChemE Car Contest</dt>
    <dd>
        Thomas Christensen II, Andrew Halverson, Kennedee True, Seth Messick, Amanda Christensen, Caleb Richmond,
        Alexander Brown, & Jake Maksin with Dr. David Bagley
        <br />
        Rocky Mountain Regional AIChE Student Conference &#9679; Golden, CO &#9679; April 6, 2019
        <br />
        2<sup>nd</sup> Place Poster Competition &#9679; 7<sup>th</sup> Place Performance Competition
        <br />
        <a href="https://hdl.handle.net/20.500.11919/3817">Publication Link</a>
        &emsp;
        <a data-toggle="collapse" data-target="#cheme-car" role="button">Abstract <span class="caret"></span></a>
        <div class="collapse" id="cheme-car">
            <p class="font-serif">The ChemE Car That Cud showcases Wyoming&rsquo;s dominant industries of agriculture and
                mining by utilizing rumen fluid from a cannulated beef cow to generate hydrogen to be used in a hydrogen
                fuel cell and radioactive cesium, a byproduct of uranium that is often obtained from Wyoming&rsquo;s mines, to
                time the car&rsquo;s stop. The concentration of cesium-137 source is measured using the radioactive decay of
                cesium shielded by aluminum. The painted aluminum chassis was obtained from a previous team at UW, and
                modified using plastic k&rsquo;nex toys to adapt to the current power source and stopping mechanism.</p>
        </div>
    </dd>

    <hr />

    <dt>Measuring Diffusion of Trichlorethylene Breakdown Products in Polyvinylalginate</dt>
    <dd>
        Thomas A. Christensen II, Samuel R. Wolfe, Jonathan Counts, Mark F. Roll, Kristopher V. Waynant, James G.
        Moberly
        <br />
        AIChE Annual Meeting &#9679; Pittsburgh, PA &#9679; October 29, 2018
        <br />
        3<sup>rd</sup> Place Environmental III Division Undergraduate Poster Competition
        <br />
        <a href="https://aiche.confex.com/aiche/2018/meetingapp.cgi/Paper/545790">Conference Schedule Listing</a>
        &emsp;
        <a data-toggle="collapse" data-target="#pva-aiche" role="button">Abstract <span class="caret"></span></a>
        <div class="collapse" id="pva-aiche">
            <p class="font-serif">Trichloroethylene (TCE), a toxic and carcinogenic contaminant, presents unique
                challenges for cleanup because of its water solubility, density, and volatility. Bioremediation of TCE
                is a promising cleanup method; however, metabolism of TCE results in acid generation that inhibits
                remediating microorganisms. Calcium alginate(CA)-polyvinylalcohol (PVA) hydrogels show promise for
                protecting remediating microbes, however diffusion of TCE or its byproducts through these polymers is
                unknown. To measure the effective diffusion coefficient of TCE and byproducts through hydrogel
                membranes, we used a modified diaphragm cell. Measured effective diffusion coefficient of each species
                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
                cis-1,2-dichloroethylene (DCE), and 4.68 ± 4.14 for vinyl chloride. These results aid in engineering
                biobeads and suggest that CA-PVA hydrogel blends are effective in slowing diffusion of protons,
                buffering acids produced by trichloroethylene metabolism, and remains suitable for encapsulation of
                microorganisms involved in bioremediation.</p>
        </div>
    </dd>

    <hr />

    <dt>How to build a cow-cud fuel cell</dt>
    <dd>
        Thomas A. Christensen II
        <br />
        Idaho INBRE Summer Research Conference &#9679; Moscow, ID &#9679; August 1, 2018
        <br />
        3<sup>rd</sup> Place Fast-Pitch Science Presentation Contest
        <br />
        <a href="https://web.archive.org/web/20190928024416/https://inbre.uidaho.edu/research/research-conference/">Awards
            Listing</a>
    </dd>

    <hr />

    <dt>Measuring diffusion of protons in polyvinylalginate</dt>
    <dd>
        Thomas A. Christensen II, Jonathan Counts, James G. Moberly
        <br />
        Idaho INBRE Summer Research Conference &#9679; Moscow, ID &#9679; July 31, 2018
        <br />
        Undergraduate Poster Competition
        <br />
        <a
            href="https://eventmobi.com/idahoinbre2018/people/c861bd6f-f4a7-4d67-a59a-199e34515776/387725dc-c893-44b6-b611-0abdf5fbcf6e">Conference
            Schedule Listing</a>
        &emsp;
        <a data-toggle="collapse" data-target="#pva-inbre" role="button">Abstract <span class="caret"></span></a>
        <div class="collapse" id="pva-inbre">
            <p class="font-serif">Trichloroethylene (TCE) is a toxic and carcinogenic contaminant that presents unique
                challenges for cleanup because of its density and volatility. Use of microorganisms may be a promising
                remediation method, however metabolism of TCE results in acid buildup, which consequently impedes the
                ability of microorganisms to perform this remediation. Polyvinylalginate (PVA) shows promise as a useful
                shield for microorganisms carrying out bioremediation of TCE by surrounding them in a protective
                biofilm-like layer, however, key information is missing which relates diffusion of TCE or its metabolic
                products through PVA. To measure the effective diffusion coefficient of H+ ions through a PVA membrane
                cross-linked with boric acid and calcium ions, we used a modified diaphragm cell. We found the effective
                diffusion coefficient to be 1.40 × 10<sup>-5</sup> ± 1.91 × 10<sup>-6</sup> cm<sup>2</sup>/s, a nearly
                seven-fold decrease in diffusivity compared to protons in water, with an unexpected significant but as
                of yet unquantified adsorption capacity. These results suggest that polyvinylalginate is effective in
                slowing diffusion of protons and buffering these acids produced by trichloroethylene metabolism, and
                remains suitable for encapsulation of microorganisms involved in bioremediation.</p>
        </div>
    </dd>
</dl>