Gas chromatography - mass spectrometry (GC-MS) is a widely used analytical technique for separating and identifying volatile and semi-volatile compounds in complex mixtures. It is beneficial to research ways of increasing sample throughput (i.e. decreasing analysis time) while not losing any chemical information. This study investigates the change in volatile chemicals (odors) that are emitted from banana peels in varying stages of ripeness. The headspace of banana peels was first analyzed using Solid Phase Micro-Extraction (SPME) with a standard gas chromatograph and a quadrupole mass spectrometer (qMS). For demonstrating a viable platform for increased sample throughput, the samples were then analyzed on a LTM (Low Thermal Mass GC) coupled to a Time-of-Flight mass spectrometer. The banana peel analyses on the LTM-TOFMS decreases the run time by tenfold when compared with the traditional GC-qMS. A new data analysis program developed by the Synovec Lab is used to visualize the data and identify compounds.

This research traces the origins of electron density fluctuations in the HIT-SI experiment. HIT-SI is a magnetic confinement experiment that uses two helicity injectors to initialize and sustain current in the confinement region. Densities of 1-10e19 m^-3 with density fluctuations related to the injector frequency are measured with an FIR interferometer. After spheromak formation, injector currents flow in the direction of toroidal current in the confinement volume. Peaks in the density fluctuations are seen when the injector current passes through the beam path of the interferometer. These observations are consistent with particle motion in the direction of injector current as expected by anti-dynamo action in this region. Furthermore, we have observed fluctuations that indicate that the injector current displaces the confined current. Calculating the toroidal current centroid from surface magnetic probe measurements as a function of time provides further testing of this model. Understanding density fluctuations allows a more complete description of the physics of current drive in HIT-SI.

‘Aigarchaeota’ is a candidate phylum of Archaea known only by 16S rRNA gene fragments from cultivation-independent microbial surveys and a single composite genome from Candidatus ‘Caldiarchaeum subterraneum’, an inhabitant of a subterranean gold mine in Japan. Gene sequences reported in various publications were found almost exclusively in geothermal settings, but a comprehensive assessment has not yet been performed. The purpose of this study was: (i) to rigorously define the phylum; (ii) to gain insight into the phylogenetic and potential taxonomic structure of the phylum; (iii) to assess the distribution of ‘Aigarchaeota’; and (iv) to design ‘Aigarchaeota’-specific 16S rRNA gene primers. Public databases were mined for 16S rRNA gene sequences related to known ‘Aigarchaeota’ and a combination of approaches were used to rigorously define the phylogenetic boundaries of the phylum and compile a neighbor-joining and maximum likelihood phylogenetic tree. Primer template gene sequences were aligned in ClustalW in order to locate regions that are suitable for targeting genus-level groups. ‘Aigarchaeota’-specific primers for the polymerase chain reaction (PCR) amplification of 16S rRNA genes were designed using sequence alignments and reviewed using the Ribosomal Database Project Probe Match tool. The analyses supported the proposed relationship between ‘Aigarchaeota’, Thaumarchaeota, Crenarchaeota, and Korarchaeota in the so-called ‘TACK’ superphylum, and identified ~300 16S rRNA genes and gene fragments affiliated with ‘Aigarchaeota’, including those recovered from terrestrial geothermal systems on several continents and marine geothermal and subsurface samples. ‘Aigarchaeota’ belonged to at least three family- to order-level groups and at least 13 genus-level groups which are represented in the resulting phylogenetic tree. All genus-level groups were recovered from geographically distant locations, suggesting a global distribution. The primers will be used to determine the presence and abundance of ‘Aigarchaeota’ in a wide variety of samples from terrestrial geothermal systems in the U.S. and Asia using quantitative real-time PCR.

The Farnsworth-type IEC reactor was once considered to behave as a point source of neutrons with reference to the spherical central accelerating grid. This was assumed because the deuteron-deuteron fusion reaction is inherently spherically symmetric (isotropic), and current theory suggested that the vast majority of fusion events were occurring in the deepest region of the potential well (the accelerating grid, which is also the geometric center of the reactor). However, anecdotal evidence has suggested that isotropy may not be empirically accurate. Our main objective was to conclusively test the assumption by measuring deviations from uniformity in the neutron flux. To measure this we used three different types of detector: CR39 plastic, BTI bubble detectors and He-3 dosimeters. We exposed the CR39 slides to fast neutrons (2.45 MeV) at a fluence of 10^6 n/cm^2, and they indicated apparent anisotropy (p-value of .0035) with higher flux at the front and rear of the machine. The BTI bubble detectors and He-3 tubes also corroborated a higher neutron density at those sites. We then hypothesized that beam loading on the front and rear conflats by the plasma "jets" emanating from the central cathode could be responsible. Measurements with paired He-3 tubes after blocking the jets with quartz glass showed the apparent anisotropy reduced by 38% on average (p << .001). This quantitative confirmation of anisotropy, and the significant (but not sole) role that beam-target fusion plays therein, represents an important shift in the understanding of the Farnsworth-type reactor, which could have important implications in plasma physics and the development of fusion energy.

In the past few years there have been large amounts of research done on the benefits of adding metallic nanoparticles into carbon fiber reinforced epoxy composites. The goal of this study is to estimate the effect of nanoparticle additives on the residual stress development in a Double Box Beam carbon fiber reinforced composite structure. Carbon fiber composites are being used in many aerospace applications as a means of weight savings due to their high strength to weight ratio. If residual stress can be reduced, the carbon fiber composite will have increased strength, fatigue resistance, and allow for more precise manufacturing tolerances. The through-hole drilling method is used to test for residual stresses induced by the thermal curing process. Using ASTM Standard Test Method E 837, the test shows the strains before and after the hole was drilled which is associated with the relaxation strain. Working backwards from this relationship and using the equations associated with this method, a value for residual stress was found. Looking at the effect nanoparticles have had on previous research, we can estimate the amount of residual stress present in the Double Box Beam structure with nanoparticles. If time permits values will be validated experimentally by a Double Box Beam with nanoparticles incorporated. Compiling this data gives a clear understanding of how nanoparticles will affect the curing cycle and the residual stress.

The budding yeast, Saccharomyces cerevisiae is a single-celled eukaryote that provides many advantages for use as a model organism, including the ease of genetic and environmental manipulation. The replicative lifespan assay is a commonly used method for quantifying the lifespan of yeast by measuring the number of times an individual mother cell can divide. My laboratory has found that yeast lacking genes encoding subunits of the vacuolar ATPase (V-ATPase) have an extremely short replicative lifespan. The V-ATPase is a multisubunit protein complex that pumps protons across membranes and acidifies intracellular organelles, such as the lysosome-like vacuole in yeast. Lysosomes are organelles in eukaryotic cells containing digestive enzymes that break down and digest macromolecules and waste products. Yeast provides an ideal model for the study of disruption of the V-ATPase as they are able to survive loss of this complex, which is essential in most other eukaryotes. Vma21 is a protein required for the assembly of the V0 subunit of the V-ATPase. I have observed that vma21 mutants are short-lived, have a respiratory growth defect, and are sensitive to low iron levels. My experimental model demonstrates that supplemental iron and antioxidants, such as sodium ascorbate (vitamin C), dramatically increase the shortened lifespan of vma21 mutants. Supplemental iron also rescues the respiratory defect of vma21 mutants. My data supports a model where loss of V-ATPase function results in disrupted iron homeostasis leading to loss of mitochondrial function and shortened lifepsan, which can be rescued by supplemental iron and antioxidants.

The Rieske iron-sulfur protein (Rip1) is a nuclear encoded protein that assembles into the cytochrome bc1 complex of the electron transport chain in budding yeast, Saccharomyces cerevisiae. The iron-sulfur cluster bound by this protein facilitates the flow of electrons during cellular respiration in the inner membrane of the mitochondrial matrix. In the nematode worm, Caenorhabditis elegans, a mutation in a conserved residue of the Rieske iron-sulfur protein has been found that delays development and extends the lifespan of this organism. Mutagenesis experiments from our laboratory have identified suppressors of this C. elegans developmental phenotype that are due to secondary mutations in conserved residues within a flexible hinge region of the Rieske iron-sulfur protein. The primary mutation and secondary suppressing mutations were introduced to the yeast Rip1 gene through site directed PCR mutagenesis. Transgenic yeast have been created expressing the mutant forms of Rip1 homologous to those identified in C. elegans. The next stages of my project will entail the characterization of these mutations in yeast. I plan to assay the replicative lifespan, growth rate, respiratory efficiency, as well as sensitivity to variance in temperature, reactive oxygen species and carbon source in an effort to understand how this mutant’s lifespan extension fits into the larger picture of known aging pathways. The extrapolation of the mechanisms found in these model organisms serve as the basis for understanding our own complex aging process.

 In neurodegenerative diseases, such as Alzheimer’s disease, tau protein aggregation is observed. In Alzheimer’s disease and related conditions, accumulation of insoluble tau impairs physiological function that ultimately leads to neuron loss. Using a transgenic Caenorhabditis elegans model that expresses human tau protein in neurons, we are able to see accumulated, insoluble, phosphorylated tau, and uncoordinated movement (Unc) phenotypes in these organisms. To identify genes participating in aggregated tau and Unc phenotypes, we conducted a mutagenesis; an estimated 20,000 worm genomes were screened and we isolated seven promising strains of C. elegans that carried loss of function genes suppressing the tau-induced phenotypes. These strains are currently being sequenced to determine the identity of the loss of function genes, which may represent novel suppressors of tau pathology. Currently, the Kraemer lab has identified two genes suppressing tau-induced Unc phenotype and called them suppressor of tau 1 (sut-1) and suppressor of tau 2 (sut-2). Animals with sut-1 and/or sut-2 mutations are resistant to the negative effects of tau, meaning that the proteins made by these genes are necessary for tau phenotypes. With this knowledge and the additional information to be gained from the sequencing of seven novel sut alleles, we hope that potential neuroprotective approaches for treatment can be developed.