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You searched for +publisher:"University of Southern California" +contributor:("Boedicker, James Q."). Showing records 1 – 3 of 3 total matches.

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University of Southern California

1. Guggemos, Nicholas Greening. A measurement of the dielectric properties of water nanoclusters.

Degree: PhD, Physics, 2015, University of Southern California

Dielectric properties of neat (H₂O)n clusters and mixed acid‐water clusters, doped with deuterium chloride, in the range 3 ≤ n ≤ 9 were measured by electric field deflection of a neutral supersonic beam. Neutral acid‐water clusters were produced by attaching acid molecules to pure clusters in an expanding supersonic jet of water. ❧ A synchronous detector was developed for this experiment. The detector is built from commodity hardware costing between one‐tenth and one‐fifth as much as comparable commercial alternatives. Sensitivity is more than an order of magnitude better than the analog system it replaced, and the design does not require complex setup to obtain optimal performance. The new detector additionally offers better immunity to noise than the aforementioned commercial systems through the use of digital optical isolators, which break ground loops. ❧ Cluster beam profiles are known to have a Gaussian shape, but it seems that no published formula exists to calculate the variance of the parameters of a Gaussian fit (unlike, e.g., the linear case). Prior experiments have used a quadratic approximation so that fitting parameter variances could be estimated. A program was written to implement the “Bootstrap” statistical re‐sampling technique to estimate the variance of the Gaussian beam fit parameters. ❧ Square‐modulated cluster beam velocity measurement techniques from the literature require fitting a Multi‐channel Scaler (MCS) record with certain properties to a time‐resolved flux formula. A method and program for normalizing MCS records without these properties is presented. Further, the normalization and fitting method is able to accurately measure beam velocity from variable‐length MCS records containing an arbitrary number of chopper cycles. ❧ Polarizabilities of neat clusters were found to correspond with previous experiments. Polarizability of mixed clusters, measured for the first time, was found to rise between n=5 and n=6, which may be evidence of disassociation of the DCl molecule. This experiment may offer insight into the problem of defining solvation for finite‐sized systems. Advisors/Committee Members: Kresin, Vitaly V. (Committee Chair), Dappen, Werner (Committee Member), Däppen, Werner (Committee Member), Daeppen, Werner (Committee Member), Wittig, Curt F. (Committee Member), El-Naggar, Mohamed Y. (Committee Member), Boedicker, James Q. (Committee Member).

Subjects/Keywords: nanoclusters; water clusters

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Guggemos, N. G. (2015). A measurement of the dielectric properties of water nanoclusters. (Doctoral Dissertation). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/437394/rec/239

Chicago Manual of Style (16th Edition):

Guggemos, Nicholas Greening. “A measurement of the dielectric properties of water nanoclusters.” 2015. Doctoral Dissertation, University of Southern California. Accessed April 26, 2019. http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/437394/rec/239.

MLA Handbook (7th Edition):

Guggemos, Nicholas Greening. “A measurement of the dielectric properties of water nanoclusters.” 2015. Web. 26 Apr 2019.

Vancouver:

Guggemos NG. A measurement of the dielectric properties of water nanoclusters. [Internet] [Doctoral dissertation]. University of Southern California; 2015. [cited 2019 Apr 26]. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/437394/rec/239.

Council of Science Editors:

Guggemos NG. A measurement of the dielectric properties of water nanoclusters. [Doctoral Dissertation]. University of Southern California; 2015. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/437394/rec/239


University of Southern California

2. McFarlane, Ian. Microbially synthesized chalcogenide nanostructures: characterization and potential applications.

Degree: PhD, Physics, 2015, University of Southern California

Microbial redox activity offers a potentially transformative approach to the low-temperature synthesis of nanostructured inorganic materials. Diverse strains of the dissimilatory metal-reducing bacteria Shewanella are known to produce photoactive filamentous arsenic sulfide nanomaterials by reducing arsenate and thiosulfate in anaerobic culture conditions. Here we report in situ microscopic observations and measure the thermally activated (79 kJ mol⁻¹) precipitation kinetics of high yield (504 mg per liter of culture, 82% of theoretical maximum) extracellular As₂S₃ nanofibers produced by Shewanella sp. strain ANA-3, and demonstrate their potential in functional devices by constructing field effect transistors (FETs) and photoelectrochemical cells (PECs) based on individual nanofibers and nanofiber mats respectively. The use of strain ANA-3, which possesses both respiratory and detoxification arsenic reductases, resulted in significantly faster nanofiber synthesis than other strains previously tested, mutants of ANA-3 deficient in arsenic reduction, and when compared to abiotic arsenic sulfide precipitation from As(III) and S²⁻. I propose and support a new pathway for arsenic sulfide precipitation based on behavior of ANA-3 mutants. Detailed characterization by electron microscopy, energy-dispersive X-ray spectroscopy, electron probe microanalysis and Tauc analysis of UV-vis spectrophotometry showed the biogenic precipitate to consist primarily of amorphous As₂S₃ nanofibers with an indirect optical band gap of 2.37 eV. X-ray diffraction also revealed the presence of crystalline As₈S₉₋ₓ minerals that, until recently, were thought to form only at higher temperatures and under hydrothermal conditions. The nanoscale FETs enabled a detailed characterization of the charge mobility (≈ 10⁵ cm² V⁻¹ s⁻¹) and gating behavior of the heterogeneously doped nanofibers. PECs produced hundreds of nA of current when exposed to 2 mW of light. These studies indicate that the biotransformation of metalloids and chalcogens by bacteria enables fast, efficient, sustainable synthesis of technologically relevant chalcogenides for potential electronic and optoelectronic applications. Advisors/Committee Members: El-Naggar, Mohamed Y. (Committee Chair), Kresin, Vitaly V. (Committee Member), Boedicker, James Q. (Committee Member), Haas, Stephan W. (Committee Member), Finkel, Steven E. (Committee Member).

Subjects/Keywords: Shewanella; arsenic sulfide; nanostructures; biomaterial; biogenic materials; field effect transistor; photoelectrochemical cell; ANA-3

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

McFarlane, I. (2015). Microbially synthesized chalcogenide nanostructures: characterization and potential applications. (Doctoral Dissertation). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/598830/rec/4062

Chicago Manual of Style (16th Edition):

McFarlane, Ian. “Microbially synthesized chalcogenide nanostructures: characterization and potential applications.” 2015. Doctoral Dissertation, University of Southern California. Accessed April 26, 2019. http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/598830/rec/4062.

MLA Handbook (7th Edition):

McFarlane, Ian. “Microbially synthesized chalcogenide nanostructures: characterization and potential applications.” 2015. Web. 26 Apr 2019.

Vancouver:

McFarlane I. Microbially synthesized chalcogenide nanostructures: characterization and potential applications. [Internet] [Doctoral dissertation]. University of Southern California; 2015. [cited 2019 Apr 26]. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/598830/rec/4062.

Council of Science Editors:

McFarlane I. Microbially synthesized chalcogenide nanostructures: characterization and potential applications. [Doctoral Dissertation]. University of Southern California; 2015. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/598830/rec/4062


University of Southern California

3. Gross, Benjamin J. From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces.

Degree: PhD, Physics, 2015, University of Southern California

Metal‐reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. By performing electron transfer to synthetic electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. This ability enables the emerging technology of microbial fuel cells (MFCs), where living cells utilize complex or mixed biofuels to produce electricity. The exact mechanism of this extracellular electron transport, however, is not yet fully understood. ❧ In the first part of this work I focus on the role of calcium in MFCs innoculated with Shewanella oneidensis MR-1. Calcium is known to play important roles in cellular metabolism, including aggregation of cells onto surfaces. It has been shown that the addition of calcium to MFCs results in increased current. Here we use electrochemical impedance spectroscopy (EIS) and equivalent circuit modeling to determine that calcium is not simply increasing the current by abiotically reducing the solution resistance, and may prove useful as a biological optimization parameter. ❧ In the next section I focus on the role of pili in MFC current production. Shewanella oneidensis MR-1 produce type IV pili which may play an important role in biofilm formation and current production in MFCs. MFCs have permitted the measurement of current output from mutants lacking the ability to produce certain extracellular appendages thought to play a role in current production. Our results prove ambiguous due to the bulk nature of MFC measurements which cannot determine whether differences in current production are due to factors uniformly impacting the entire culture, or heterogeneities in the phenotypical behavior of different cells. ❧ In order to address these issues, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect sub-pA currents associated with single cell direct electron transfer (DET) events. ❧ Finally, I demonstrate the system with single cell measurements of the dissimilatory metal reducing bacterium Shewanella oneidenis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. Mutants lacking the flavin export system (Δbfe) also did not produce current at the single‐cell level. Only one out of 28 contact events showed a current… Advisors/Committee Members: El-Naggar, Mohamed Y. (Committee Chair), Kresin, Vitaly V. (Committee Member), Haas, Stephan W. (Committee Member), Finkel, Steven E. (Committee Member), Boedicker, James Q. (Committee Member).

Subjects/Keywords: Shewanella oneidensis; optical trapping; direct electron transfer; microbial fuel cells

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Gross, B. J. (2015). From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces. (Doctoral Dissertation). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/573743/rec/2910

Chicago Manual of Style (16th Edition):

Gross, Benjamin J. “From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces.” 2015. Doctoral Dissertation, University of Southern California. Accessed April 26, 2019. http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/573743/rec/2910.

MLA Handbook (7th Edition):

Gross, Benjamin J. “From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces.” 2015. Web. 26 Apr 2019.

Vancouver:

Gross BJ. From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces. [Internet] [Doctoral dissertation]. University of Southern California; 2015. [cited 2019 Apr 26]. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/573743/rec/2910.

Council of Science Editors:

Gross BJ. From fuel cells to single cells: electrochemical measurements of direct electron transfer at microbial-electrode interfaces. [Doctoral Dissertation]. University of Southern California; 2015. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll3/id/573743/rec/2910

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